Category: Featured Articles

Multilevel Modeling of Resection Accuracy: Insights from 10,144 Clinical Cases using A Contemporary Computer-Assisted Total Knee Arthroplasty System (Abridged Version)

Clinical Contributors

James I. Huddleston III, MD
Stanford University Medical Center
Redwood City, CA

Bernard N. Stulberg, MD
Saint Vincent Charity Medical Center
Cleveland, OH

Technical Contributors

Laurent Angibaud, Dipl. Ing.
Exactech, Inc.

Charlotte Bolch

Exactech, Inc.

Yifei Dai, PhD
Exactech, Inc.

Cyril Hamad, Dipl. Ing.
Blue Ortho

Amaury Jung, Dipl. Ing.
Blue Ortho


As a successful treatment for advanced inflammatory and degenerative knee arthritis, total knee arthroplasty (TKA) is projected to expand by 600% to more than three million cases annually by 2030.1 Associated with the exponential growth, an expected increase of revision TKA cases can be a substantial financial burden to both patients and society. Inaccurate surgical resections and the resultant malalignment are among the most common reasons for TKA failure.2 These etiologies may also contribute to the phenomenon of 20% “unhappy” patients,3,4 as they have been shown to lead to worse functional and clinical outcomes compared to those of well-aligned knees.5-8

Numerous studies have confirmed the benefit of computer assisted orthopedic surgery (CAOS) in improving the accuracy of bony resection and limb alignment.9,10 However, there are some common shortcomings shared across the existing studies that often fall into the following categories: 1) the studies are not sufficiently powered to investigate geographic and inter-surgeon variance; 2) limited data is available on the ”learning curve” to gain full benefit of a technology with a surgeon’s early adoption of the technology; 3) longitudinal performance of a specific CAOS system over time has been overlooked, despite constant updates in the software and hardware as a standard practice in most marketed systems; and 4) even though published meta-analyses offer global reviews of the CAOS technology, by nature, device differences and associated technical variations are excluded from the analyses, leading to significant differences in accuracy reported between CAOS systems.11

It is unquestionably difficult to initiate clinical studies that encompass sufficient cases for the assessment of individual factors that may influence accuracy. Current cloud-based infrastructure now allows the archiving of technical data without the need to assess specific patient information, enabling comprehensive accuracy assessments based on a large number of cases performed by a given CAOS system. However, the large dataset is often accumulated at multiple levels (hierarchically structured), posing a unique challenge for analysis as it may violate the assumptions of common analytic methods such as linear regression. Multilevel modeling offers several advantages to address the challenge,12 including: 1) no requirement of independence for individual observations; and 2) effects of both individual and specific groups can be analyzed against the outcome of interest comprehensively and concurrently. This methodology has been applied to assess healthcare data variations in multiple categories, such as geographic region, socioeconomic status, and different attributes in care networks based on large datasets.13-15

By integrating the above described concepts of CAOS system specific accuracy performance, consideration of multiple factors that may impact accuracy, and methods for analyzing hierarchical data, this study aimed to apply multilevel modeling to assess resection accuracy across the entire TKA application history of a modern CAOS system. Specifically, the authors sought to determine the impact on accuracy from 1) geographic region; 2) inter-surgeon difference; 3) surgeon’s adoption of the technology (learning vs proficiency); 4) preoperative mechanical alignment status; and 5) historical progression of the CAOS application (software versions).

Materials and Methods

A retrospective review was conducted based on a proprietary cloud-based web that archives all TKAs performed using a modern imageless CAOS system (ExactechGPS®, Blue-Ortho, Gieres, FR). All completed cases are stored as deidentified reports that contain only technical information on the surgery (no patient information of any sort). Similarly, all surgeons are de-identified with only their geographic information (country of practice) available. A set of grouping categories were identified as variables that might affect alignment accuracy, including geographic regions, inter-user differences across established surgeons (surgeons with at least 50 cases experience with the CAOS system), adoption phases, preoperative mechanical alignment status, and versions of the CAOS software application (Table 1).

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Table 1. Grouping variables for the assessment of variability.

*The selection of ≥ cases to define established surgeons was based on consideration of maintaining sufficient sample size per category.

The following surgical parameters were extracted (Figure 1): 1) planned resection: the resection parameters determined by the surgeon prior to the bony resection. These parameters reflected the surgeon’s resection targets for the CAOS guidance; 2) checked resection: digitalization of the actual bony resection surfaces, acquired based on the actual bony resection using an instrumented checker.

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Figure 1. A) Alignment target was planned before bony resection, and B) digitized after bony resection using an instrumented checker. Resection error in alignment was calculated as the deviation from the planned resection to the checked resection.

Resection errors (accuracy) were assessed between the planned and actual resections in the coronal plane referencing the mechanical axis, for both the tibia and femur. A resection was considered acceptable if there was no more than 2° of error. Unconditional multilevel modeling was applied to understand whether and where the variability was located in the resection errors in both tibia and femur with regard to the grouping categories. For each model, level-1 and level-2 variances, as well as the intraclass correlation (ICC) were computed. Specifically, the following questions were explored:

  1. Does significant variability exist in resection errors in any grouping category(-ies)?
  2. If variability is found to exist in a grouping category, is it clinically meaningful?

The first question was answered by the identification of any significance (p < 0.05) from a z test on the variance estimate of the level-2 variability related to a specific grouping category. In order to answer the second question, an intraclass correlation coefficient (ICC) value greater than the common variability from observational type studies (reported as ICC = 0.15 – 0.2516) indicated the existence of meaningful variability in alignment accuracy for the associated grouping category.


A total of 10,144 CAOS TKA cases were reviewed. Overall, the percentages of cases with acceptable coronal alignment were 97.9% and 97.2% for the tibia and femur respectively. The alignment results exhibited excellent accuracy across all established surgeons (acceptable resections ranged between 92% and 100% of the cases, Figure 2). For both tibia and femur, greater than 95% of the cases exhibited acceptable resections across geographic regions, adoption phases, preoperative alignment categories, and CAOS application versions (Figure 3).

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Figure 2. Percentage of acceptable resections (<2° alignment error) across individual surgeons.

Figure 3. Percentage of acceptable resections (<2° alignment error) across grouping categories of geographic region, adoption phase, preoperative alignment, and application version.

Variation in geographic region, CAOS software application versions, preoperative alignment, and adoption phases (learning/proficient) all exhibited negligible amounts of total variability in resection errors for both tibia and femur (insignificant z tests on level-2 variance estimates, ICC values < 0.004, Table 2). Although significant variability was found among individual surgeons (p values ≤ 0.001), the associated ICC values (0.02 and 0.07 in tibia and femur resection errors, respectively) were lower than the common variability from observational type studies.16

Table 2. Variance estimates and ICC values for level II variables from multilevel models. Note that extremely low (0.0000) variance estimates were found across categories in some group variables (meaningful standard error not observed). The associated z-value and p-value were not calculated as the data did not support a hypothesis test (z-test).


Numerous studies have shown that malalignment in the coronal plane can lead to various complications in TKA, such as component loosening and instability, polyethylene wear, and patellar dislocation.5-7 Despite the consensus on the importance of alignment accuracy, only 70–80% of the conventionally instrumented TKA cases can achieve satisfactory lower limb alignment (within 3° of varus/valgus relative to the mechanical axis).17,18 In contrast, this study demonstrated excellent accuracy in bony resection alignment achieved with the modern CAOS system studied. Furthermore, the resection accuracy was not sensitive to geographic region, inter-surgeon difference, learning period, preoperative mechanical alignment status, or CAOS software application version.

To the authors’ knowledge, this is the first data analysis applying advanced statistical modeling to assess the accuracy of a specific CAOS system across all cases in its application history, comprehensively considering factors that may influence the bony resection alignment. All, not just selective, surgeons, geographic regions, preoperative alignment conditions, software versions, and phases of adoption were assessed, making this analysis a robust and unbiased review of the accuracy performance of this CAOS system.

Researchers have questioned the accuracy of limb alignment measures based on standard long-leg standing load-bearing radiographs, as it may be compromised by the quality of the image, inter- and intra- observer variability, as well as the rotation of the limb or oblique direction of the beam. Although three-dimensional computer tomography (CT) analysis is suggested for a more accurate alignment measurement,19 a universal CT evaluation for all patients in this study was impractical. The choice of intraoperative instrumented measurement provided a consistent and accurate 3-D method for assessing resection alignment accuracy.

In conclusion, this study applied an advanced statistical tool to provide a comprehensive, clinically relevant evaluation of a modern CAOS system for total knee arthroplasty. The analysis considered potential impact from an extensive list of factors for a thorough understanding of resection errors based on a large data set collected through the application history of the system. The analysis outcomes demonstrated that the studied modern CAOS system offers an accurate and precise solution to help the surgeon achieve their surgical resection goal.

*The full version of this article can be found in Volume 27, Issue 3 of The Knee.


  1. Kurtz SM, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89(4):780–5.
  2. Schroer WC, et al. Why are total knees failing today? Etiology of total knee revision in 2010 and 2011. J Arthroplasty 2013;28(8 Suppl):116–9.
  3. Bourne RB, et al. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 2010;468(1):57–63.
  4. Scott CE, et al. Predicting dissatisfaction following total knee replacement: a prospective study of 1217 patients. J Bone Joint Surg Br 2010;92(9):1253–8.
  5. Choong PF, Dowsey MM, Stoney JD. Does accurate anatomical alignment result in better function and quality of life? Comparing conventional and computer assisted total knee arthroplasty. J Arthroplasty 2009;24(4):560–9.
  6. Blakeney WG, Khan RJ, Palmer JL. Functional outcomes following total knee arthroplasty: a randomised trial comparing computer-assisted surgery with conventional techniques. Knee 2014;21(2):364–8.
  7. Huang NF, et al. Coronal alignment correlates with outcome after total knee arthroplasty: five-year follow-up of a randomized controlled trial. J Arthroplasty 2012;27(9):1737–41.
  8. Longstaff LM, et al. Good alignment after total knee arthroplasty leads to faster rehabilitation and better function. J Arthroplasty 2009;24(4):570–8.
  9. Brin YS, et al. Imageless computer assisted versus conventional total knee replacement. A Bayesian meta-analysis of 23 comparative studies. Int Orthop 2011,35(3):331-9.
  10. Hetaimish BM, et al. Meta-analysis of navigation vs conventional total knee arthroplasty. J Arthroplasty 2012,27(6):1177-82.
  11. Carli A, et al. Inconsistencies between navigation data and radiographs in total knee arthroplasty are system dependent and affect coronal alignment. Can J Surg 2014;57(5):305–13.
  12. Osborne JW. Advantages of hierarchical linear modeling. Pract Assess Res Eval 2000;7(1):1–4.
  13. Sizmur S. Multilevel analysis of inpatient experience. Report from Picker Institute Europe; 2011 March. Multi-level-analysis-of-inpatient-experience.pdf.
  14. Lumme S, Leyland AH, Keskimaki I. Multilevel modeling of regional variation in equity in health care. Med Care 2008;46(9):976–83.
  15. Uddin S. Exploring the impact of different multi-level measures of physician communities in patient-centric care networks on healthcare outcomes: a multi-level regression approach. Nat Sci Rep 2016;6(20222):1–10.
  16. Hedges LV, Hedberg EC. Intraclass correlation values for planning group-randomized trials in education. Educ Eval Policy Anal 2007;29(1):60–87.
  17. Ritter MA. The anatomical graduated component total knee replacement: a long-term evaluation with 20-year survival analysis. J Bone Joint Surg Br 2009;91:745–9.
  18. Bourne RB, et al. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 2010;468(1):57–63.
  19. Ueyama H, et al. Two-dimensional measurement misidentifies alignment outliers in total knee arthroplasty: a comparison of two- and three-dimensional measurements. Knee Surg Sports Traumatol Arthrosc 2019;27(5):1497–503.
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State-of-the-Art in Reverse Shoulder Arthroplasty: A New Small Baseplate System Brings rTSA to a New Level

Rahul Deshmukh, MD

Orthopaedic Associates of Wisconsin

Shoulder arthroplasty is currently the most effective means of treating end-stage glenohumeral osteoarthritis in modern medicine. While over the past decades innovation has created substantial improvements in primary shoulder arthroplasty (rTSA) , it was not until the advent of reverse shoulder arthroplasty that a substantial expansion of the overall indications and applications for shoulder arthroplasty could actually occur. Present day, rTSA has eclipsed primary shoulder arthroplasty as the most commonly performed shoulder arthroplasty procedure worldwide, as the indications have rapidly expanded from treating rotator cuff tear arthropathy to proximal humerus fracture, and irreparable rotator cuff tears to primary osteoarthritis. Despite this rapid growth in indications, innovation in rTSA design has lagged behind—until now.

Exactech’s Equinoxe® Platform Shoulder System has been a market leader in helping surgeons treat patients with an increasing variety of clinical scenarios. By providing a robust number of options in terms of angled augments, as well as variability in offset and lateralization, the Equinoxe System provides a platform arthroplasty solution for surgeons. Until now, a critical limitation of the Equinoxe Reverse System had been the size of the baseplate. Originally based upon dimensions of the larger stature individuals seen in the western world, the standard Equinoxe baseplate has distinct limitations when used for smaller stature patients commonly encountered in Asian populations. With the creation of the Small Reverse Shoulder, rTSA with the Equinoxe System can now be accurately and effectively performed in virtually all anatomy types.

Exactech Equinoxe Small Reverse Shoulder Baseplates

Small-stature and associated small glenoid morphologies have long proven challenging for surgeons interested in performing primary and especially rTSAs. This challenging clinical scenario is a common occurrence in the U.S. rTSA markets but even more critical in the Asian markets. This discrepancy is even more apparent given the difference in clinical presentation of shoulder pathology in Asian populations. The incidence of primary osteoarthritis in Asian populations is exceedingly low. Rather, the most common indication for shoulder arthroplasty in Asian markets is for treatment of rotator cuff tear arthropathy. Indeed, rTSA represents 80% of the shoulder arthroplasty market in Asia.1 Furthermore, this market is growing rapidly with an expected 41% growth rate in China and over 300% growth rate in Korea in the next five years.1,2

With the standard baseplate, fully half of the world’s population has been excluded from the benefits of the Exactech Equinoxe Reverse System. In computer modeling studies of 100 small-stature glenoids, detailed analysis of height, width and vault depth were performed. Results demonstrated substantial size differences compared to the Western population, especially significant in females. With an average glenoid height and width of 33 x 24 mm respectively and a vault depth of less than 15 mm, small-stature females start off with smaller dimensions than the actual standard Equinoxe baseplate.3 With onset of arthritis, erosions and bone loss, the size discrepancy becomes even more pronounced. Indeed, one study examining accuracy of baseplate implantation in Asian glenoids demonstrated that implantation with a standard baseplate had a 33% perforation rate of the bone cage. Of the remaining cases in which the cage remained in the vault, 25% were in suboptimal positioning. Just slightly over 40% were able to be correctly placed.1

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The Small Reverse Shoulder has multiple features which may provide for enhanced glenoid fixation.

The new Small Reverse Shoulder and enhanced reverse shoulder system comprise a major evolutionary step for the Exactech Equinoxe platform stem. Using data from the proprietary CT analysis discussed previously, the Equinoxe Small Reverse Shoulder achieves a width dimension similar to competitors on the market yet has expansion capabilities (through augments, glenosphere options and humeral liners) to handle a variety of clinical scenarios in both small and large stature patients. Furthermore, by incorporating key design features of the standard Equinoxe Shoulder System, the team was able to provide the same robust characteristics that have led to over a decade of clinical success. Among these critical elements include enhancements intended to reduce scapular notching, improve glenoid fixation and provide a seamlessly integrated design within the Equinoxe System.

The Equinoxe Reverse Shoulder has been shown to dramatically reduce scapular notching by seven-fold;4,5 the Small Reverse Shoulder design was based on the clinically proven Equinoxe design. The baseplate is anatomically shaped with dimensions of 29.5mm x 23.9mm and is 24.4% smaller than the current Equinoxe baseplate.6 This combination, along with built-in baseplate offset, enables a shift in glenosphere position in an effort to avoid scapular notching while maintaining precise glenoid placement. Furthermore, the elongated glenosphere articular surface and new chamfered sides were designed to facilitate easier insertion, improve inferior offset and increase range of motion. The matching humeral implant retains the same 145-degree neck angle, which enables lateralization of the humerus without lateralizing the center of rotation.

The Small Reverse Shoulder has multiple features which may provide for enhanced glenoid fixation. The implant features the same curved backside as the standard baseplate, designed to minimize bone removal and convert shear forces into stabilizing compressive forces. By maintaining the same central cage diameter but shortening it (13.1mm vs 16.6mm) and shifting it to a slightly more central position, the small reverse baseplate provides initial fixation strength while limiting vault penetration or malposition in smaller glenoid anatomy.6,7 The same variable angle compression screws with locking caps enhance the initial fixation and compression, while unique to the Equinoxe Reverse Shoulder; the central cage with addition of bone graft inserted inside helps to promote bone through-growth and long-term biologic fixation.8 As a result of the smaller size and anatomic shape, the smaller baseplate design allows for greater percent surface area of contact with eroded glenoids such as those with a biconcave pattern. Finally, for more complex glenoid morphology, the baseplate will soon be offered in a superior (10 degrees), posterior (8 degrees) and superior/posterior configuration.

The Small Reverse Shoulder is designed to seamlessly integrate with the entire Equinoxe System. The current 36mm and 40mm glenospheres are available with 0mm and 2.5mm liners and lock into the existing humeral tray system providing full compatibility with the Equinoxe Platform stems. Lateralized versions of both 36 and 40mm glenospheres will be released in 2019 allowing for even greater flexibility with soft tissue balancing, anatomic tensioning of the remaining rotator cuff and improved deltoid wrap. With a wide range of augmented glenoid baseplates available to address various types of glenoid wear, the small reverse baseplate was designed to allow for revision flexibility even in the most limited of bone stock.

The Small Reverse Shoulder system is a game-changing innovation for the Equinoxe Shoulder System. The Equinoxe Reverse Shoulder has long been a leader in reducing scapular notching, providing enhanced glenoid fixation and providing a seamlessly integrated design.9,10 With the addition of the Small Reverse Shoulder, Exactech now sets the industry standard for providing this robust array of features in treating both small and large glenoid morphology. Indeed, with the new Exactech Small Reverse Shoulder, surgeons worldwide will be able to address a wider range of clinical shoulder problems than ever before making sure to have a great day in the O.R.

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  1. Yamakado, K. (2018). Worldwide Growth of TSA: The Emerging Asian-Pacific Market.
  2. Tian, L., Radhakrishnan, P. and Archila, D. (2013). MediPoint GlobalData. Total Shoulder Replacement: Global Analysis and Market Forecasts.
  3. Matsuki, Keisuke, et al. Three-dimensional measurement of glenoid dimensions and orientations. Journal of Orthopaedic Science (2018).
  4. Mollon, Brent, et al. Impact of scapular notching on clinical outcomes after reverse total shoulder arthroplasty: an analysis of 476 shoulders. Journal of shoulder and elbow surgery 26.7 (2017): 1253-1261.
  5. Roche, C. P., et al. Scapular notching and osteophyte formation after reverse shoulder replacement: radiological analysis of implant position in male and female patients. The bone & joint journal 95.4 (2013): 530-535.
  6. 718-04-45 Equinoxe Small Reverse Shoulder Operative Technique Addendum
  7. 718-01-30 Equinoxe Platform Shoulder System Operative Technique
  8. Data on file at Exactech.
  9. Simovitch, R., et al. (2019). Impact of scapular notching on reverse total shoulder arthroplasty midterm outcomes: 5-year minimum follow-up. Journal of shoulder and elbow surgery.
  10. Mollon, B., et al. (2017). Impact of scapular notching on clinical outcomes after reverse total shoulder arthroplasty: an analysis of 476 shoulders. Journal of shoulder and elbow surgery26(7), 1253-1261.

Anterior Cruciate Ligament Reconstruction Using Platelet Rich Plasma and Tenomend™

Paul R. Fleissner, Jr., MD

Crystal Clinic Orthopaedic Center

This article has been modified by the author for length to facilitate inclusion in Innovations. The original article, “Outcomes of Anterior Cruciate Ligament Reconstruction Using Biologic Augmentation in Patients 21 Years of Age and Younger,” is available at


Anterior cruciate ligament (ACL) injuries are commonly encountered in the practice of sports medicine with current literature estimating an incidence of 100,000 to 200,000 cases per year.1,2 Among adolescent populations, these injuries are becoming more prevalent. Recent reports have suggested that the numbers are steadily growing, with an incidence of 0.1 to 2.4 patients per 100,000 annually.

Regardless of graft and technique, reports have shown an increased risk of graft failure in the younger population compared with the adult population. Graft failure after successful anterior cruciate ligament reconstruction (ACLR) in patients 21 years of age or younger is as high as 25% or more in some studies.1,3 The use of biologic agents, such as platelet-derived growth factors, remains an area of interest as surgeons explore new means to improve healing. In cases of ACLR, this adjunct is thought to enhance the overall integrity of the reconstructed ligament.4

Although a certain amount of fibrin clot forms in vivo after post-surgical trauma, concentrating specific growth factors that are found within a clot, (e.g., PRP), may have unrealized potential. Plasmin, which is also found with increased intra-articular concentrations after athletic or post-surgical trauma, has been shown to degrade fibrin and may prevent effective delivery of beneficial growth factors.5 With this in mind, collagen scaffolds represent an intriguing adjunct, as soluble collagen can slow plasmin-mediated degradation of fibrin.6

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Figure 1. Intraoperative arthroscopic photograph of a left knee from a standard anterolateral viewing portal demonstrating final anterior cruciate ligament graft placement. An overlying porous collagen carrier has been sutured to circumferentially cover the hamstring autograft, and platelet rich plasma has been injected into the graft.

Figure 1. Intraoperative arthroscopic photograph of a left knee from a standard anterolateral viewing portal demonstrating final anterior cruciate ligament graft placement. An overlying porous collagen carrier has been sutured to circumferentially cover the hamstring autograft, and platelet rich plasma has been injected into the graft.


Institutional review board approval was obtained. Patients 21-years of age or younger who underwent ACLR utilizing autologous hamstrings and biologic augmentation (PRP and porous bovine collagen membrane, TenoMend, Collagen Matrix, Ramsey, NJ), with a minimum of two years follow-up were enrolled. All patients completed physical therapy and answered outcome questionnaires, including IKDC, Lysholm, Tegner and SANE. They also answered questions concerning whether they had sustained an ipsilateral or contralateral ACL injury since their initial ACLR, positive family history for ACL injury, return to the same sport after ACLR that they had played previously and subsequent surgery on the reconstructed knee since the ACLR (Figure 1).

Patients were rehabilitated using the protocol developed by the MOON study group. Patients were required to complete all 5 phases of the protocol and pass functional testing prior to returning to sports. Serial Lachman testing was performed postoperatively and at final follow-up. Patients were tested at final follow-up for pivot shift phenomenon and by KT-1000 arthrometer.

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Initially, there were 194 patients eligible for this study; 143 patients involving 151 knees met the inclusion criteria and completed follow up questionnaires. The mean patient age was 16 years, range 8 to 21 years. The average time to complete physical therapy was 22 weeks, range 12 to 41 weeks. After completion of physical therapy, 132 patients (92%) returned to their preinjury level of activity. The average total follow-up duration was 52 months, range 25 to 94 months. Seven cases (5%) of ipsilateral ACL injury occurred that required revision surgery, with an average time to injury of 17 months. There were 23 contralateral ACL injuries (15%) at an average time of 28 months from the initial surgery.

Mean IKDC and Lysholm scores were 91 and 91, with a range of 55 to 100 and 57 to 100, respectively. Tegner scoring was the same both preoperatively and postoperatively in 138 of 151 knees; 11 scores were lower postoperatively than preoperatively, whereas 4 scores were higher postoperatively. The mean Tegner score preoperatively was 9, range 5 to 10, whereas the mean Tegner postoperative score was 9, range 4 to 10. The average SANE score was 94, range 60 to 100.

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Figure 2. The same patient as in Fig 1, 7 months after the initial procedure. Patient was reevaluated with diagnostic and operative arthroscopy after sustaining a new injury while playing basketball. The reconstructed ACL has fully incorporated, with demonstrated ligamentization and neovascularization, again visualized from a standard anterolateral viewing portal.

Figure 2. The same patient as in Fig 1, 7 months after the initial procedure. Patient was reevaluated with diagnostic and operative arthroscopy after sustaining a new injury while playing basketball. The reconstructed ACL has fully incorporated, with demonstrated ligamentization and neovascularization, again visualized from a standard anterolateral viewing portal.


Mean IKDC and Lysholm scores were 91 and 91, with a range of 55 to 100 and 57 to 100, respectively. Tegner scoring was the same both preoperatively and postoperatively in 138 of 151 knees; 11 scores were lower postoperatively than preoperatively, whereas 4 scores were higher postoperatively. The mean Tegner score preoperatively was 9, range 5 to 10, whereas the mean Tegner postoperative score was 9, range 4 to 10. The average SANE score was 94, range 60 to 100.

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This study using biologic augmentation (PRP with porous bovine collagen membrane, TenoMend), with hamstring autograft in ACL reconstruction in patients 21-years of age or younger shows a decreased rate of second ACL injury, specifically regarding ACL revision surgery. The patients in this study also show a higher return to preinjury level of competition at a faster rate than other studies have shown.

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  1. A.J. Wiggins, R.K. Grandhi, D.K. Schneider, D. Stanfield, K.E. Webster, G.D. Myer. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: A systematic review and meta-analysis. Am J Sports Med, 44 (2016), pp. 1861-1876.
  2. M. Ahldén, K. Samuelsson, N. Sernert, M. Forssblad, J. Karlsson, J. Kartus. The Swedish National Anterior Cruciate Ligament Register: A report on baseline variables and outcomes of surgery for almost 18,000 patients. Am J Sports Med, 40 (2012), pp. 2230-2235.
  3. T.J. Dekker, J.A. Godin, K.M. Dale, W.E. Garrett, D.C. Taylor, J.C. Riboh. Return to sport after pediatric anterior cruciate ligament reconstruction and its effect on subsequent anterior cruciate ligament injury. J Bone Jt Surg, 99 (2017), pp. 897-904.
  4. Weiler, C. Förster, P. Hunt, et al. The influence of locally applied platelet-derived growth factor-BB on free tendon graft remodeling after anterior cruciate ligament reconstruction. Am J Sports Med, 32 (2004), pp. 881-891.
  5. M.M. Murray, K.P. Spindler, C. Devin, et al. Use of a collagen-platelet rich plasma scaffold to stimulate healing of a central defect in the canine ACL. J Orthop Res, 24 (2006), pp. 820-830.
  6. M.E. Kroon, M.L.J. van Schie, B. van der Vecht, V.W.M. van Hinsbergh, P. Koolwijk. Collagen type 1 retards tube formation by human microvascular endothelial cells in a fibrin matrix. Angiogenesis, 5 (2002), pp. 257-265.
  7. P. Vavken, P. Sadoghi, M.M. Murray. The effect of platelet concentrates on graft maturation and graft-bone interface healing in anterior cruciate ligament reconstruction in human patients: A systematic review of controlled trials. Arthroscopy, 27 (2011), pp. 1573-1583.
  8. M. Vogrin, M. Rupreht, D. Dinevski, et al. Effects of a platelet gel on early graft revascularization after anterior cruciate ligament reconstruction: A prospective, randomized, double-blind, clinical trial. Eur Surg Res, 45 (2010), pp. 77-85.
  9. E. Lopez-Vidriero, K.A. Goulding, D.A. Simon, M. Sanchez, D.H. Johnson. The use of platelet-rich plasma in arthroscopy and sports medicine: Optimizing the healing environment. Arthroscopy, 26 (2010), pp. 269-278.
  10. M. Orrego, C. Larrain, J. Rosales, et al. Effects of platelet concentrate and a bone plug on the healing of hamstring tendons in a bone tunnel. Arthroscopy, 24 (2008), pp. 1373-1380.
  11. F. Radice, R. Yánez, V. Gutiérrez, J. Rosales, M. Pinedo, S. Coda. Comparison of magnetic resonance imaging findings in anterior cruciate ligament grafts with and without autologous platelet-derived growth factors. Arthroscopy, 26 (2010), pp. 50-57.
  12. M. Sánchez, E. Anitua, J. Azofra, R. Prado, F. Muruzabal, I. Andia. Ligamentization of tendon grafts treated with an endogenous preparation rich in growth factors: Gross morphology and histology. Arthroscopy, 26 (2010), pp. 470-480.
  13. Silva, R. Sampaio. Anatomic ACL reconstruction: Does the platelet-rich plasma accelerate tendon healing? Knee Surg Sport Traumatol Arthrosc, 17 (2009), pp. 676-682.
  14. K.P. Spindler, M.M. Murray, J.L. Carey, D. Zurakowski, B.C. Fleming. The use of platelets to affect functional healing of an anterior cruciate ligament (ACL) autograft in a caprine ACL reconstruction model. J Orthop Res, 27 (2009), pp. 631-638.
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An Outpatient Approach and Protocol for Total Hip Arthroplasty

Matthew Price, MD
Ellis & Badenhausen Orthopaedics


Total Hip Arthroplasty (THA) has been a successful, increasing practice for caring for hip arthritis in the aging and active population. The advent of new techniques and efficiency has advanced the practice to one of the more reproducible and beneficial operations orthopaedic surgeons perform. Because of the increasing age of the American population, the need and number of hip replacements performed is expected to increase over the coming decades.1 With that in mind, surgeons have been advancing the practice of joint replacement in both the knee and the hip to accommodate the active lifestyles and demands of patients.2,3 More and more patients desire to be home in a timely manner and get back to work and daily activities as soon as they can tolerate. Several studies have shown the benefits and successful outcomes of an outpatient approach to joint replacement surgery.3-5

This article presents one surgeon’s experience with transitioning to outpatient total hip arthroplasty and the development of a successful outpatient program. Over the past two and a half years, the technique has evolved and patients were followed to determine whether this idea was plausible. The thought being that patients who are healthy enough and motivated to go home after surgery might recover just as well as those who had traditionally stayed in a hospital for two—sometimes three—days. Our practice has instituted an outpatient hip replacement model that has been used successfully in both the hospital and ambulatory surgery center settings.

This article presents one surgeon’s experience
with transitioning to outpatient total hip arthroplasty and the development of a successful outpatient program.


Preoperative Evaluation
The discussion of any surgery can be an anxious and stressful time for patients. Setting the patient up for success starts with the in-office discussions. Oftentimes conversations are directed at finding and understanding their goals and expectations. Just like all procedures, we discuss the surgery in detail, including the risks and benefits. However, patients are often surprised to hear that they might be able to go home the same day as their surgery. As the reader knows, patients come with preconceived notions from the experiences of friends and family members, so hearing for the first time that outpatient surgery is an option can help alleviate some anxieties regarding surgery.

We have come to understand that the pre-operative discussions help set the patient up for the best possible outcomes. When a patient feels educated, they also feel empowered, and we spend a good amount of time discussing the advantages and disadvantages of a hospital stay versus going home. The discussion often focuses on comfort and control. Obviously, surgery can be a stressful experience, and the comforts of home can allow them to rest and recover in a more hospitable environment. Between the call lights, beeping IV equipment, other patients’ needs on the floor, nurses doing assessments at all hours of the night and unknown surroundings, it can be difficult for patients to even find an uninterrupted night of rest. Being able to have the comforts of home, literally, at their fingertips often dilutes some of the anxieties patients feel when discussing surgery. The ability to sleep in their own bed, use their own restroom facilities and sit in their favorite recliner eases the tension when surgery is in the future.

In addition to the discussion, we stratify patients whom we consider to be good candidates for outpatient surgery in partnership with our primary care and anesthesia providers. All patients are assessed pre-operatively by both services for proper clearances, lab studies and further work-up if needed. Patients with co-morbidities, which might lead to untoward events, are not considered for an outpatient procedure. ASA scores of three or greater are automatically marked as overnight stays. Patients with diabetic control issues are likewise deemed to be better hospital admits. Regarding diabetics, we typically will not schedule any elective total hip unless hgbA1c levels are seven or less. Morbidly obese (i.e., BMI greater than 40) patients are set up with a dietician and bariatric surgery consult prior to surgery scheduling and return every three months prior to surgery while we follow trends in their weight loss. Patients who show consistent weight loss and are moving toward their goal weight with BMI less than 40 are considered for surgery. We have a strict cutoff for BMI less than 40 at the surgery center for all cases. Patients with prior complications of surgery or anesthesia are not scheduled as outpatient cases.

After stratifying patients for hospital versus surgical center-based surgery, we then have patients attend a pre-operative class designed for total joints. It is run by the hospital and includes topics to expect before, during and after surgery. It includes discussions on what to expect the day of surgery, anesthesia approach, ambulation protocols, wound care discussion, home care, pain control, follow up expectations and therapy protocols. The class was designed by our combined years of practice experience and common core practices, with input from pre-anesthesia nurses, physical therapy, social cares advisors and nursing staff. In addition to the pre-operative testing and the anesthesia evaluation, this class serves to answer basic questions patients have regarding issues they may experience at home. For instance, placement of rugs at home, the use of crutches or walker at home, or bath mats in the shower, to name a few, are discussed. Again, our approach is to educate the patient as much as possible before the surgery, so they know what to expect when the time comes for recovery. This limits anxious phone calls to the office, decreases unexpected case cancellations, and empowers the patient to feel confident when preparing for their surgical experience.

Day of Surgery Pre-op
As with most surgeons, the legwork before surgery depends on a dedicated team of medical assistants, schedulers and nursing staff committed to providing the best experience for the patient as possible. By the time the day of surgery comes, patients have been properly evaluated and educated on expectations, have had their questions answered and are confident when they arrive.

Most patients receive the same anesthesia care for our total hip replacements. What started in 2014 as spinals for all patients has evolved to the use of epidurals with catheters. Our facility happens to be the largest infant delivery center in the state, and thus, the anesthesia providers are quite proficient at both spinals and epidurals. After careful consideration, and discussion, we have chosen the epidural route for a couple of reasons. First, the ability to perform in the pre-operative area allows the flow of surgery to proceed more smoothly throughout the day. With two surgical suites available, this process allows the anesthesia team to remain ahead of the day’s schedule and requires less room coordination. Second, the ability to re-dose an epidural has several advantages. With a spinal, cases need to be more strictly coordinated to be performed within the two-hour surgical window. Also, in the event of uncontrolled post-operative pain, a re-dosing of the epidural in the post-anesthesia unit is possible. As with both spinal and epidural anesthesia, the potential for urinary retention is possible, and we have instituted the use of 0.4 mg of Flomax (tamsulosin hydrochloride) one week prior to surgery for patients 50 years of age and older. In addition, our anesthesia team uses a multimodal approach for pain control the day of surgery, which includes 200 mg of Celebrex, 300 mg of Gabapentin, and 400 mg of IV Acetaminophen.

All cases are performed with the same team involving the room nurse, surgical scrub tech and a first assist. At the hospital, we use two rooms with two teams, while at the surgery center we have one room for these procedures. All cases are performed using the Hana® table, and we utilize the modified Smith-Peterson approach described by Matta et al.6 The preferred instrumentation is the Novation® Crown Cup and the Alteon® Tapered Wedge Stem. In addition, we use an intra-operative fluoroscope to assist with abduction angle, medial placement and ante-version of the cup, as well as determining proper leg length and abductor offset with overlaying radiographs while in the surgical suite. The patient is transferred to post-anesthesia recovery with a cooling device placed over the dressing intended to be started in recovery and without any use of abduction pillows or bracing.

Goals to be accomplished before discharge are: ambulating greater than 75 feet, ability to perform and climb stairs (we have a stair model in recovery) and ability to void urine before discharge.

Post-Anesthesia Recovery and Transition to Home

Once in the recovery unit, the patient is almost immediately encouraged to sit up in bed. The nursing staff first will determine the patient’s level of pain and begin oral pain medications as soon as they are consciously aware to drink and eat. They will begin to allow the patient to begin the process of eating more solid foods and sitting at the side of the bed. In addition, the Physical Therapy team is notified of the patient’s arrival, and our goal is to have them ambulating within one hour of transfer to post-anesthesia care. We encourage the use of crutches after surgery for ambulation. In coordination and discussions with our physical therapy providers, it was decided that we use crutches instead of a walker, when feasible, reducing the awkwardness and difficulty of managing a walker in the home and transportation. However, patients are assessed for coordination and comfort of both devices before discharge. Goals to be accomplished before discharge are: ambulating greater than 75 feet, ability to climb stairs (we have a stair model in recovery) and ability to void urine before discharge. The team is instructed that the accomplishment of these goals is paramount to their discharge, and in some cases, a second round of therapy before discharge is undertaken.

As discussed, the pre-operative assessment and plan upon discharge has been discussed with the patient prior to arriving at the hospital. Our office’s pre-operative nurse and social services team have coordinated an in-home nurse to meet them at the house on the day of discharge. This allows the patient to have access to coordinated care, and addresses any questions should the need arise on the day of surgery. Oftentimes, this visit serves to answer any lingering questions after surgery as well as asses the home for any possible transfer or ambulatory issues (such as chairs and rugs) which might prove challenging for their recovery. In addition, we utilize in-home physical therapy on post-operative day one. Our goal is to have the patient transitioned to an outpatient therapy center as soon as they feel comfortable to be out of the house more consistently.

Post-Operative Follow-up
All patients are followed up in our office four weeks after surgery for wound check and radiographs. Most questions of pain and renewal of medications are handled by our office nurse. Patients are anti-coagulated with 325mg of enteric-coated Aspirin twice daily for 21 days. Those patients with prior history of chemotherapy, DVTs, PEs, etc. are usually prescribed 2.5mg of Eliquis twice daily. This is all pre-determined by our office and their primary care providers, and usually the therapy is concluded before the first office visit. As discussed, the use of crutches versus a walker is made prior to discharge, and many patients have transitioned to a cane or no assistive device by the time of follow-up. Patients with wound care concerns are brought into the office sooner, and coordinated with our office nurse handling those calls. Patients will then follow-up at the three-month interval for radiographs and activity assessment. If recovery has proceeded smoothly, they are then seen again at their one-year appointment.


We only considered and defined outpatient surgery as those patients discharged the same day as surgery. While developing this protocol, we started to follow our average length of stay in the hospital. Prior to developing our outpatient program, in 2014 our average length of stay in the hospital was 2.3 days. We performed one outpatient total hip in that year. In 2015 we performed a total of 147 primary total hip replacements. Of those, 27 (or 18%) were performed on an outpatient, same day as surgery, discharge basis. In addition, in the first full year of actively scheduling outpatient hip replacements, our average length of stay in the hospital dropped to 1.7 days. In 2016 we performed 167 primary total hip replacements. Of those, 56 (or 34%) were performed on an outpatient basis. In 2016 our average length of stay for those admitted dropped again to 1.3 days. The length of stay data was only recovered for total hips that were admitted. In 2015 we had no re-admissions from our outpatient population. In 2016 we had one re-admission for urinary retention issues while at home.


The transition to performing outpatient total hip replacements is an evolving process. My senior partner performed the first total knee and total hip in our state back in the 1970s. After spending time with Maurice Edmond Mueller in Bern, Switzerland, he returned and began performing the procedure in our local hospitals. At the time, patients would stay admitted to the surgical floor for 5-7 days, followed by an extended stay in the therapy unit. Oftentimes patients were not allowed to ambulate fully weight-bearing for the first 1-2 weeks, and abduction braces were occasionally utilized, for fear of dislocation. We have come a long way since the 1970s.

Prior to developing our outpatient program, our average length of stay in the hospital was 2.3 days. In 2015 the first full year of actively scheduling outpatient hip replacements, our average length of stay dropped to 1.7 days.

In 2014 we performed the first outpatient total hip at one of our facilities. By chance, the patient had a prior total hip replacement on the opposite side, was healthy and very active. He requested and inquired if it was possible we might let him go home after the procedure. After his first procedure, he was walking the hallways that night on the hospital floor, independently climbing stairs and went home the next morning. He relayed that he could not sleep well in the hospital and that he did not like being around patients that might be sick. That got us thinking, and after careful consideration and evaluation by both his primary care providers and the anesthesia team, we scheduled our first total hip as an outpatient procedure. That experience led us to begin developing a pathway of protocols for developing an outpatient experience for total hip replacements.

As a fellow in Nashville, it was not rare to have patients discharged on post-op day one. However, they weren’t listed, nor expected, to be discharged unless they had met certain discharge criteria. While developing this protocol, we started to follow our average length of stay in the hospital. Prior to developing our outpatient program, our average length of stay in the hospital was 2.3 days. In 2015 the first full year of actively scheduling outpatient hip replacements, our average length of stay dropped to 1.7 days. The following year in 2016, our average length of stay dropped again to 1.3 days. That data was for all total hips, which were full admits to the hospital. We found that in conjunction with the development of outpatient total joint program, our scheduled overnight admissions stayed for shorter periods. In addition, the number of outpatient procedures went up. We believe that as expectations went up for those expected to go home on the same day, so too did the expectations rise for those being admitted to the hospital.

We have recognized that most of the success of this program starts in the office. When patient’s expectations are met with their surgeon’s expectations, the results changed and improved regarding admissions. If a patient is expected to get up and ambulate on the same day as surgery, most of the time they will accomplish that goal. One of the keys to that success is reiterating your desires and goals for patients with the nursing staff and physical therapy teams. We meet regularly (once a month) to review protocols, discuss challenges, make changes when necessary, and adjust plans if patterns that do not work are identified. In addition, in the age of rising medical care costs, increased patient insurance premiums and demand, the discharge of patients in a timely manner will help decrease the overall burden on the system.

The author believes that outpatient total hip replacements have a place in the realm of total joint arthroplasty. The development of that process takes time and effort to coordinate and execute. Our next step will be to include VAS as well as Harris Hip scores, and specifically stratifying those patients who have experienced both an inpatient and outpatient surgery. We also would like to assess the cost savings to the system and compare inpatient and outpatient costs, as has been done in other studies.7 With time, outpatient total joint replacements may become the norm. After all, it was not too long ago when patients were admitted for months on end.

1. Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and
revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone and Joint Surgery. 2007; 89:780-785.
2. Berger RA, Sanders S, Gerlinger T, Della Valle C, Jacobs JJ, Rosenberg
AG. Outpatient total knee arthroplasty with a minimally invasive
technique. J Arthroplasty. 2005;20(Suppl 3):33–38.
3. Berger RA, Sanders SA, Thill ES, Sporer SM, Della Valle C. Newer anesthesia and rehabilitation protocols enable outpatient hip replacement
in selected patients. Clin Orthop Relat Res. 2009;467:1424–1430.
4. Dorr LD, Thomas DJ, Zhu J, Dastane M, Chao L, Long WT. Outpatient total hip arthroplasty. J Arthroplasty. 2010;25:501–506.
5. Goyal N, Chen AF, Padgett SE, Tan TL, Kheir MM, Hopper Jr RH, Hamilton WG, Hozack WJ. A multicenter, randomized study of outpatient versus inpatient total hip arthroplasty. Clin Orthop Relat Res. 2017; 475: 364-372.
6. Matta JM, Shahrdar C, Ferguson T. Single-incision Anterior Approach
for Total Hip Arthroplasty on an Orthopaedic Table. Clin Orthop Relat Res. 2005; 441: 115-124.
7. Bertin, Kim C MD. Minimally Invasive Outpatient Total Hip Arthroplasty:
A Financial Analysis. Clin Orthop Relat Res. 2005; 435: 154-163.


Performing Total Shoulder Arthroplasty in an Outpatient Setting

Rick Papandrea, MD
Orthopaedic Associates of Wisconsin

Although considered cutting edge only a few years ago, outpatient total shoulder arthroplasty (TSA) has now become routine at some facilities. What follows are some current thoughts, as well as recent past experiences of the author performing total shoulder arthroplasty in an outpatient setting.

In this article, outpatient total shoulder arthroplasty will include both same day discharges and 23-hour overnight stays. Total shoulder arthroplasty, whether an anatomic, or reversed implant, is deemed an inpatient procedure by Medicare. Therefore, total shoulder arthroplasty cannot be done at an outpatient facility for a Medicare patient. This review will not consider any specifics of the Medicare population for that reason.

Over the past four years, this author’s ambulatory surgery center has performed 369 total shoulder arthroplasties. One hundred seventy nine were anatomic devices, 190 were reversed devices. Before embarking on outpatient total shoulder arthroplasty, both the surgeon and facility must consider the necessary components required for both a safe and successful program.

Surgeons who desire to utilize such a program should first have the skill set to reliably and efficiently perform total shoulder arthroplasty. There needs to be confidence in not only completion of the procedure, but the awareness necessary to predict in whom the procedure can most efficiently and effectively be carried out. Surgeons who routinely require prolonged operative times, especially for glenoid exposure might want to consider honing their skills set prior to performing outpatient arthroplasty. Likewise, the surgeon must be cognizant of the challenging factors that make certain patients more appropriate in a hospital setting. Severe bone loss, significant stiffness, and obesity are all reasons to give pause when considering patient selection. The surgeon must be completely aware of, and confident in the capabilities of the specific arthroplasty system chosen.

Over the past four years, this author’s ambulatory surgery center has performed 369 total shoulder arthroplasties. One hundred seventy nine were anatomic devices, 190 were reversed devices.

I have found the Exactech Equinoxe® system ideal for outpatient arthroplasty due to the extreme flexibility it provides. When utilizing the anatomic system, a backup with the reverse system will allow treatment of unexpected severe rotator cuff pathology, or glenoid deficiency and deformity. Augmented glenoid components, both reverse and anatomic, have essentially eliminated the need for bone graft. This not only saves time in the operating room, it limits the additional equipment and support needs of the facility.

When planning and implementing a shoulder arthroplasty service at an outpatient facility the support staff, the surgeon, and the implant representative need to be aware of, and in sync with the ancillary equipment needs. There needs to be clear understanding of any potential need, such as alternative retractors, cerclage fixation for iatrogenic fractures, polymethylmethacrylate and associated delivery systems for unexpected fixation needs.

Although it may not be the first thought or consideration, insurance reimbursement must be understood prior to initiation of a program for outpatient shoulder arthroplasty. Many, if not most commercial contracts will include arthroplasty, consisting of CPT codes 23472, 23473, and 23474. The contracted reimbursement may or may not be sufficient to cover the overhead of the procedures. In our experience, some contracts needed to be revisited, with special carve out for these codes, prior to initiating the outpatient arthroplasty program. Having an accurate knowledge of local reimbursement rates at the hospital, by specific payors, allows for efficient and effective negotiation of outpatient reimbursement rates. Prior to initiating discussions with payors, it is helpful to obtain EOBs, or explanation of benefits forms, from patients who have undergone total shoulder arthroplasty at an inpatient facility locally. Collecting as many of these as possible will allow the surgeon and outpatient facility to formulate a competitive negotiation plan.

During the same time that the surgeon and facility are considering their ability to carry out outpatient shoulder arthroplasty, and make it financially viable, they need to be considering their physical needs.

The physical needs of the facility extend beyond the operating room. Of course, the procedure must be able to be safely, efficiently, and effectively performed in the operating room. Considerations beyond the operating room include the potential need for additional imaging, the potential for physical therapy, food service needs and recovery needs.

We have found that image fluoroscopy is sufficient for imaging in the operating room, and that it is only needed if there is concern for fracture during the case. In review of my inpatient procedures, I found that postoperative xrays, obtained in the recovery room, did not change the postoperative course of the patient. I have not been obtaining postoperative images routinely in the outpatient setting, although if one desired to do so, current mini c-arms are sufficient.

Having physical therapy see the patient prior to discharge is something that can be considered, if the facility has therapy on site, or therapy is going to visit the patient. There could be some advantages to this, especially if there is a desire to capture the patient for outpatient therapy at a specific facility postoperatively.

We have found that it is quite effective to have the patient watch a pre-recorded video of exercises prior to discharge, they can review at home prior to their first follow up as well. This home-based program has been well received, is convenient, and at times patients differ on going to formal therapy. Recent studies have shown equivalence in home therapy or formal therapy after shoulder arthroplasty.5

Planning should include consideration for the length of recovery period for a patient to be considered outpatient, Medicare rules dictate that an outpatient must be discharged 23 hours or less after they were admitted. Admission is the time of check into the facility, not the time of discharge from PACU. While these rules are Medicare based, it is our experience that commercial providers follow them.

One possible initial plan for outpatient total shoulder arthroplasty is to discharge all patients home on the same day. This obviates the need for any overnight facilities, limits food service needs, and—if the patients are recovered the same as non-arthroplasty outpatients—additional staffing needs are mitigated. This can be accomplished in a few patients, without regional anesthetic, but for the great majority most likely would require regional anesthesia. Single shot scalene blocks have the issue of wearing off in less than one day. This may cause difficulty with the patient being discharged with no pain, and then struggling with pain control at home, often in the evening hours. Patient satisfaction may suffer, there may be increased opportunities for admission or emergency department visits. Indwelling scalene catheter will eliminate this problem, but opens the possibility of other problems such as injury to the anesthetic limb,
noncompliance due to lack of pain, and the potential for anesthetic complications from the block. While complications from regional anesthetic are rare, local anesthetic nerve toxicity is dose and time dependent.1,3,6,7

We decided to initiate our program with a 23 hour, overnight stay. This requires the facility to have overnight capacity which is not only structural, but staff based. Staffing needs may be accommodated with local staffing agencies, or providing bonuses to pre-existing staff. The evening staff must start when the routine shift is done. We have found having a single nurse with ancillary help is effective for one to two patients. If we have three to four patients we have additional staff. The ancillary help with typical utilize is an EMT. We have maintained 2:1 or 1:1 staff-to-patient ratio overnight. This is obviously much higher than done in the hospital setting. This provides not only safety, but high satisfaction.

Figure 1. Routine postoperative dressing utilized by the author for all total shoulders. 1a:
Immediate appearance in the operating room. Note the blanching due to epinephrine in the local
anesthetic injected at the start of the case. This case had enough oozing that a single drain
was placed exiting posterior, through the deltoid, with a separate Tegaderm. 1b: This is a typical
appearance of a postoperative Tegaderm at the time of removal, two weeks from surgery.


We decided to initiate our program with a 23 hour, overnight stay. This requires the facility to have overnight capacity which is not only
structural, but staff based.

Most outpatient facility centers will not have on-site food services for full meal preparation. We have found that a stocked pantry is well received by patients, when combined with local food delivery from multiple restaurants.

Our shoulder arthroplasty program has given us the opportunity to contemplate much of what we do for all our shoulder arthroplasty patients. Improvements made prior to the onset of outpatient shoulder arthroplasty made it possible to consider sending patients home the day after a shoulder replacement. Additional improvements have made the process even more reliable and effective. Continued improvements have benefited both inpatient and outpatient shoulder arthroplasty, in both Medicare and commercial payor populations.

All shoulder arthroplasty patients now receive multimodal pain management. Pre-operative treatment with transexamic acid (TXA), gabapentin and MS Contin, combined with intraoperative Tylenol and Toradol gives excellent pain control, even without a block. Use of a scalene block, with or without an indwelling catheter, has been left to the discretion of the surgeon and patient. I choose to limit the use of blocks, as I find they are typically not necessary for an effective recovery and will not allow for nerve exam postoperatively. Additionally, they will often limit active use for commencement of exercises. If there are plans to stay overnight regardless, I also feel that the block will not give as much time for the patient, with the guidance of nursing, to accommodate the postoperative pain that does occur. I do also have concerns that the block that has just worn off may delay discharge within the necessary 23-hour window.

My protocol for mitigating infection risks include some maneuvers that have ancillary benefits helpful for same or next day discharge. My post-operative bandage has evolved and is now quite aligned with outpatient shoulder arthroplasty.

Patients are instructed to prescribe with Hibiclens the night before and day of surgery. Additionally, I have recently added a daily prep with benzoyl peroxide for three days to decrease skin colonization with Propracnesionibacterium acnes. At surgery, skin preparation starts with an alcohol wash, followed by Chloraprep. Ioban is used to cover and seal the entire shoulder. The incision is injected with 1% lidocaine with epinephrine, not only for some analgesia, but also for hemostasis. One gram of Kefzol is dissolved in the local, to help sterilize the intradermal layer.2,4 This, combined with the TXA makes for minimal blood loss and typically no need for a drain. The skin is closed with asubcuticular closure with Monocryl, and sealed with Dermabond. Tegaderm is applied directly over the incision. This has multiple benefits. The incision can be monitored. The Tegaderm is left in place for two weeks, and has an excellent seal due to the skin prep and lack of bleeding. Typically, the Tegaderm does not come off until it is removed at the first visit at 14 to 15 days. It is waterproof and patients can shower and even swim. This has high acceptance from the patients. They are pleased there is no need for a bandage. The appearance makes for a less “severe” appearing wound, which I believe adds confidence to the patient leaving a facility less than 23 hours after a shoulder replacement.

The growing experience of outpatient shoulder arthroplasty has confirmed that it is safe and effective. Value in healthcare has been defined as outcomes over cost. There is no doubt that outpatient shoulder arthroplasty has, and will continue to provide value to our patients.

1. Hogan, Q. H. Pathophysiology of peripheral nerve injury during regional anesthesia. Reg Anesth Pain Med 33:435-441. 2008.
2. Lee, M. J., P. S. Pottinger, S. Butler-Wu, R. E. Bumgarner, S. M. Russ, and F. A. Matsen, 3rd. Propionibacterium persists in the skin despite standard surgical preparation. The Journal of bone and joint surgery 96:1447-1450. 2014.
3. Lenters, T. R., J. Davies, and F. A. Matsen, 3rd. The types and severity of complications associated with interscalene brachial plexus block anesthesia: local and national evidence. J Shoulder Elbow Surg 16:379-387. 2007.
4. Matsen, F. A., 3rd, S. Butler-Wu, B. C. Carofino, J. L. Jette, A. Bertelsen, and R. Bumgarner. Origin of propionibacterium in surgical wounds and evidence-based approach for culturing propionibacterium
from surgical sites. The Journal of bone and joint surgery 95:e1811-1817. 2013.
5. Mulieri, P. J., J. O. Holcomb, P. Dunning, M. Pliner, R. K. Bogle,
D. Pupello, and M. A. Frankle. Is a formal physical therapy program
necessary after total shoulder arthroplasty for osteoarthritis? J Shoulder Elbow Surg 19:570-579. 2010.
6. Verlinde, M., M. W. Hollmann, M. F. Stevens, H. Hermanns, R.
Werdehausen, and P. Lirk. Local Anesthetic-Induced Neurotoxicity.
Int J Mol Sci 17:339. 2016.
7. Werdehausen, R., S. Fazeli, S. Braun, H. Hermanns, F. Essmann,
M. W. Hollmann, I. Bauer, and M. F. Stevens. Apoptosis induction by different local anaesthetics in a neuroblastoma cell line. Br J Anaesth 103:711-718. 2009.

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Reflections on a 10-Year Collaboration

Joseph Zuckerman, MD
NYU Hospital for Joint Diseases

When I was approached by Exactech in 2003 to get involved in the development of the Equinoxe® shoulder arthroplasty system, little did I know that 10 years later I would be part of the fastest-growing system in the United States.

During my first 20 years in practice, I declined many opportunities to be involved in implant design. I didn’t feel it was the right time in my career, and I was also concerned about avoiding conflicts of interest. When I was first approached by an Exactech representative, who I had known since I began practicing medicine in 1984, my decision to meet with Exactech was based on my long-standing relationship with him.

I knew of Exactech founders Bill Petty, MD and Gary Miller, PhD from their days at the University of Florida. It also was my interactions with Exactech product development experts that convinced me to move to the next stage of participating on the Equinoxe design team: meeting my potential collaborators Tom Wright, MD, and Pierre-Henri Flurin, MD.

Tom and Henri were fundamental to my participation on the Equinoxe design team. Tom is a skilled clinician and a very smart person, but most importantly he is a “regular guy,” who is easy to work with, easy to talk to and easy to collaborate with. Henri is an outstanding shoulder arthroplasty surgeon and collaborator who brought tremendous knowledge and experience to the team. Everyone on our design team is comfortable with each other, we like one another and we look forward to our meetings.

Tom and Henri were fundamental to my participation on the Equinoxe design team.

With the close working relationship we developed, we built on Henri’s replicator plate design to bring a complete shoulder arthroplasty system to market.  It was—and still is—the only system retroversion, neck angle, medial and posterior offset of the humeral head.

Over the years, we have worked together to create the first platform stem that allows surgeons to convert an aTSA to a rTSA without stem removal, and we developed a philosophy to conserve glenoid bone with augments and cage designs. Our goal was to minimize complications, such as scapular notching, that we had seen with other implant designs.

“The rest is history,” as they say. Since 2003 we have added new members to our design team, our engineering team and our product development team. Strong collaboration is also an important part of our clinical evaluators program. The meetings we have with our clinical evaluators embody the basic approach we have followed since the beginning: we recognize the importance of relationships and we work hard to support them in any way we can.

To be successful in orthopaedics, of course we had to develop a superior and innovative product. But the single, most-important factor driving our success with the Equinoxe shoulder system is the relationships that developed from that first day more than 10 years ago. •

“In 2003, I was approached by Phil Matinale, who was working for Exactech. I had known Phil since I started in practice in 1984. Phil and I developed a very nice relationship that has continued through the years.”-Joseph Zuckerman, MD

The Equinoxe core design team, collaborating since 2003.

“Although I wasn’t quite convinced Darin Johnson [pictured fourth from the left] really played baseball at a Division I school (if you consider Ivy League baseball Division I), I liked what Darin had to say and what I learned about Exactech.”—Joseph Zuckerman, MD

Members of the Equinoxe team in 2003.

“Without exception, each person we’ve added to the team has fit in very well and developed relationships that are productive, constructive and meaningful. This is nothing less than the foundational elements of the success of the Equinoxe.”—Joseph Zuckerman, MD

Recent members of the Equinoxe team.

Advertising Equinoxe at The American
Academy of Orthopaedic Surgeons
AAOS Annual Meeting in San


Equinoxe technical exhibit at the European Society for Shoulder and Elbow Surgery SECEC Congress.


From didactic lectures to cadaver courses to surgeon-to-surgeon training, the design surgeons’ participation in medical education is critical to helping surgeons improve their outcomes.

From didactic lectures to cadaver courses to surgeon-to-surgeon training, the design surgeons’ participation in medical education is critical to helping surgeons improve their outcomes.


Shoulder Arthroplasty: The Next 10 Years

Moby Parsons, MD
Seacoast Orthopedics and Sports Medicine

Arthroplasty remains an incredible intervention for patients with degenerative joint and tendon disease for which there is yet no biological solution. Although metal and plastic are foreign materials, our ability to engineer them in ways that recreates native anatomy and restores joint function is miraculous for those afflicted with pain and functional demise. Nevertheless, the durability of shoulder arthroplasty is limited both by the imminent wear of these materials as well as the forces that act upon them in relation to the underlying host bone and its pattern and degree of erosion. In the past decade, we have come to appreciate the difficulties in addressing posteriorglenoid erosion; and recent advancements, like augmented glenoids, have improved our ability to address these defects while preserving host bone and joint biomechanics. The next decade will see evolutionary forward progress in materials science, prosthesis design, surgical planning and surgical techniques. These in turn will lead to revolutionary advancements that will relegate the current state of arthroplasty into historical perspective.

Recent advancements, like augmented glenoids, have improved our ability to address these defects while preserving host bone and joint biomechanics.

Such forward progress will also confront the challenge that healthcare reform and value-based purchasing pose to scientific innovation, in those new technologies must improve value incest-effective ways. This is particularly pertinent as the burden of arthritis at a public health level brings itself to bear on health care delivery and health economics. A look at past use and forward projections shows the rate of shoulder replacement is doubling about every10 years and is estimated to reach about 55,000-60,000 cases per year by 2025. The fastest increase is in reverse arthroplasty, which is steadily overtaking anatomical shoulder arthroplasty as its indications widen. In addition, more patients are presenting in their 40s and 50s with advanced arthritis or irreparable rotator cuff tears. These patients seek solutions that permit strenuous employment, high physical demand and sustained durability to mitigate the need for revision surgery. The synthesis of mechanical engineering and biomedical engineering will aim to confront these challenges and provide innovative, lasting solutions that translate directly into better long-term outcomes for patients, both individually and at a public health level.

As follows is a glimpse of where such innovation will lead shoulder arthroplasty both in terms of clinical care, clinical outcomes and biomedical engineering

Evolutionary Changes

  • Shorter humeral stems and an increasing use of resurfacing heads in both hemiarthroplasty and total shoulder arthroplasty will allow bone conservation on the humeral side.
  • Tissue-sparing approaches, including preservation of the subscapularis insertion, will facilitate more rapid recovery and allow shoulder arthroplasty to increasingly be performed safely in an outpatient setting

Improvements in prosthesis design such as augmented glenoids will allow surgeons to better manage glenoid erosion and wear while preserving bone stock and proper rotator cuff tension.

  • Joint registries and improved capture of retrieved failed glenoids will provide a more thorough understanding of modes of glenoid failure that will in turn lead to advancements in wear resistance, hybrid fixation and shape modification
  • Enhanced imaging and computer modeling and navigation will increasingly allow surgeons to virtually plan and perform the procedure preoperatively. These same technologies along with patient-specific instrumentation will allow improved placement of both anatomical and reverse prostheses that restore proper glenoid orientation, offset and bone fixation
  • Data analytics and the drive to improve patient value will innovate clinical care toward the goal of zero complications both medically and surgically.

Revolutionary Changes

  • Materials innovation will allow for plastics that have more cartilage-like properties allowing deformation and compliance. Similarly, metals will continue to take on properties more like bone reducing problems like stress shielding and improving biological fixation on both sides of the joint.
  • Progress in biomaterials will assist the incorporation of living tissue into mechanical scaffolds that will allow self-healing and remodeling of resurfaced joints.
  • The increasing pervasion of 3-D printing in combination with imaging modalities will allow mass customization driving toward patient-specific implants designed to match native anatomy while addressing bone deficiency and wear.
  • Finally, 3-D printing of biological tissues may advance tithe point where foreign materials can be avoided altogether and joint replacement will be a purely biological procedure. •