Month: March 2017

Exactech New Scientific and Clinical Research Presented at 2017 Orthopaedic Research Society Annual Meeting

Studies Include Shoulder and Knee Arthroplasty, Orthobiologics and Computer-Assisted Surgery in Joint Replacement

GAINESVILLE, Fla. (March 30, 2017) – Exactech (Nasdaq:EXAC), a developer and producer of bone and joint restoration products and biologic solutions for extremities, knee and hip, announced today that 16 presentations featuring new scientific and clinical research in the areas of shoulder and knee arthroplasty, orthobiologics and computer-assisted surgery were presented at the 2017 Orthopaedic Research Society (ORS) annual meeting, March 19-22 in San Diego, Calif.

“As a company with a strong scientific foundation, we were pleased to have a wide-ranging scope of research represented,” said Exactech Co-founder and Executive Vice President of Research and Development Gary Miller, PhD. “These studies will provide information that will help further our company’s commitment to improving patient outcomes with proven advancements.”

Multinational patient outcomes data drawn from more than a decade of active clinical activity provided engineering and development, clinical research teams and worldwide clinical collaborators robust information to assess the evolving performance of Exactech products.

Shoulder discoveries included outcomes reports and comparisons based on humeral and glenoid implant type and such variables as gender and age of the patient.  In the use of computer assisted surgical navigation, precision and accuracy, surgeon experience and learning curve parameters were reported for various groups of knee arthroplasty patients. A knee study revealed geographic differences that could help define effective knee femoral component designs. Finally, scientists studied viability of human chondrocytes in cryopreserved cartilage fragments that could determine successful clinical application.

About Exactech

Based in Gainesville, Fla., Exactech develops and markets orthopaedic implant devices, related surgical instruments and biologic materials and services to hospitals and physicians. The company manufactures many of its orthopaedic devices at its Gainesville facility. Exactech’s orthopaedic products are used in the restoration of bones and joints that have deteriorated as a result of injury or diseases such as arthritis. Exactech markets its products in the United States, in addition to more than 30 markets in Europe, Latin America, Asia and the Pacific. Additional information about Exactech can be found at https://staging.exac.com.

Investor contacts

Jody Phillips
Executive Vice President of Finance & Chief Financial Officer
352-377-1140

Julie Marshall or Frank Hawkins
Hawk Associates
305-451-1888
EXAC@hawkassociates.com

Media contact

Priscilla Bennett
Vice President, Corporate & Marketing Communication
352-377-1140

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
Diego.

 

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.

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Optimizing Polyethylene Materials to the Application: When it Comes to Manufacturing Methods, Hips are Not Knees

Gary Miller, PhD
Exactech, Inc.

Polyethylene for joint arthroplasty inserts is manufactured in one of three ways. One very common method is to extrude ultra-high molecular weight polyethylene (UHMWPE) powder under pressure and heat, creating a long cylinder of “extruded bar” material that can be cut into sections and machined to its final dimensions (Figure 1).

Figure 1. The ram extruded polyethylene process draws resin into a cylindrical heated chamber and compresses the mass under high temperature and pressure.

The historically popular extrusion consolidation process is inexpensive and fast, but non-consolidated areas of UHMWPE powder and large variability in material properties are often observed. This variability can lead to premature wear and failure of the insert and is not used in Exactech’s hip and knee inserts.

A second method is to place the UHMWPE powder on a larger flat molding form and apply pressure and heat to consolidate a large slab that is cut into smaller pieces and machined into its final shape (Figure 2).

Figure 2. The sheet-molded polyethylene process results in a large slab that is cut into blocks or cylinders and machined to final shape.

The third method, net compression molding, creates specific precision molds for each part to fully mold them one at a time using specialized, computer-controlled equipment that applies implant-specific optimized pressure and temperature and time profiles to both heat and cool the parts using a proprietary formula (Figure 3).

Exactech Polyethlene Process

Figure 3. The net compression molded polyethylene process yields the exact shape of the articular surface.

There are advantages and disadvantages to each manufacturing method. The most important factor to consider, however, is: which method is best for each application?

Wear in hips vs wear in knees

The mechanisms for wear and failure for hips and for knees are quite different due to the differences in congruency of the articulation and the loads applied during activities of daily living. The hip is a congruent “ball and socket” joint with an orbital reciprocating motion. This leads to a dominance of abrasive wear with secondary additional damage caused by femoral neck impingement should it occur. Knees, with their less congruent articulations and rolling and sliding motion, exhibit delamination and pitting as the dominant wear mechanisms with abrasive wear as the tertiary mechanism. Because of this difference in mechanisms, hip and knee inserts benefit from different mechanical properties for their poly inserts. For hips, we look for improved abrasive wear resistance through moderate cross linking of the polymer while maintaining fracture toughness so that locking mechanism failure and cracking from impingment are avoided. In knees, fracture toughness, which is key to reducing or eliminating delamination and pitting, is a key property.

How do manufacturing processes affect wear rate?

To address the wear performance of extruded and sheet molded materials, many manufacturers apply radiation cross linking technologies that increase the cross linking density to decrease the wear rate in hip and knee articulations. While the application of radiation cross linking does improve abrasive wear behavior, it also makes the resulting materials more susceptible to oxidation and other mechanical property degradation, most notably fracture toughness. In an attempt to mitigate these undesirable effects on mechanical properties, post processing heat treatments or antioxidants are used.

There are two general types of highly cross linked UHMWPE with post processing regimens used to address the oxidation and mechanical property degradation. Both have advantages and disadvantages, depending on the application being considered. Annealed highly cross linked UHMWPE still contains residual free radicals making it susceptible to continued oxidation. Re-melted highly cross linked poly has fewer retained free radicals, however, its mechanical and fatigue/fracture toughness properties are compromised with documented potential for structural problems. More recently, antioxidant-treated polymers (vitamin E) have also been introduced, however, the treatment does not fully eliminate oxidation potential, and the long-term effects on the body are unknown.

Does higher cross linking really lead to a better acetabular insert?

Many manufacturers use a high dose of irradiation (up to 100kGy/10MRad) for enhancing cross linking to reduce the amount of volumetric wear. This, however, comes at a cost to some of the mechanical properties of this bearing surface – mainly fracture toughness, as discussed above. Exactech manufactures Connexion GXL® polyethylene components with sheet -molded UHMWPE using two precision split-doses of 25kGy each in vacuum packaging for a total of approximately 50kGy (Figure 4) to create improved cross-link density.

Figure 4. UHMWPE Fracture Toughness measured using 3-point Bend “J-Integral” Testing.6

This process provides a 59 % reduction in gravimetric abrasive wear over the clinically successful standard Exactech polyethylene while maintaining an acceptable level of fracture toughness to mitigate potential edge/impingement and locking mechanism problems (Figure 5).

Figure 5. Wear rates determined by independent lab testing at the J. Vernon Luck Orthopaedic Research Center (McKellop)7. Lysis data determined by Dowd et. al.8

What if you didn’t have to sacrifice fracture toughness to get excellent tibial insert wear rates?

Recognizing that the abrasive wear mechanism for hip implants is quite different from knee components whose dominant wear mechanisms are delamination and pitting (highly affected by fracture toughness), knee insert components made with Exactech’s proprietary net compression molding technology do not require high levels of radiation cross linking and the subsequent post-processing treatments to create the preferred performance properties for knee applications.

All of the articular surfaces of Exactech tibial polyethylene inserts are carefully molded into the part and not machined as in other processes. By the nature of this proprietary, net compression molding consolidation process, the inserts have high fatigue strength, high fracture toughness, low wear rates and are much less sensitive to oxidation after sterilization.

Comparative laboratory testing published by various manufacturers and researchers shows that Exactech’s net compression molded polyethylene has demonstrated approximately 6X less wear than extruded UHMWPE. This is achieved without sacrificing other important mechanical properties. (Figure 6)

Figure 6. Comparative wear rates for several styles of implants and materials show the net compression molded Opterak articulation being among the lowest wear rates when compared to competitive implants.

Conclusion

The longevity and clinical results of total knee and total hip replacement components depend upon many factors. Exactech, using methods that optimize both mechanical and material properties to match the implant design and application, offers significant improvements in implant performance.


References
1. Data on file at Exactech, Inc.
2. McKellop H, Shen FW, Lu B, Campbell P, Salovey R. Development of an extremely wear-resistant ultra high molecular weight polyethylene for total hip replacements. J Orthop Res. 1999 Mar;17(2):157-67.
3. Dowd JE, Sychterz CJ, Young AM, Engh CA. Characterization of Long-Term Femoral-Head-Penetration Rates. Association with and Prediction of Osteolysis. J Bone Joint Surg Am. 2000 Aug;82-A(8):1102-7.
4. Furman BD, Lai S, Stephen Li S. A comparison of knee simulator wear rates between directly molded and extruded UHMWPE. Presented at Society for Biomaterials, 2001.
5. Herrera L, Sweetgall J, Essner, A, Wang A. Evaluation of sequentially cross linked and annealed wear debris. World Biomaster Cong., Amsterdam, May 28-Jun 1, 2008, 583
6. Papannagari R, Hines G, Sprague J, Morrison M. Long-term wear performance of an advanced bearing knee technology. ISTA, Dubai, UAE, Oct 6-9, 2010.
7. Ezzet KA, Hermida JC, Collwell CW, D’Lima DD. Oxidized zirconium femoral components reduce polyethylene wear in a knee wear simulator. Clin Orhtop 428:120-124, 2004
8. https://www.stryker.com/jointreplacements/sites/triathlon/implants.php 

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Deltopectoral, Superolateral or Rotator Cuff Sparing? Soft-Tissue Considerations Associated with TSA Approaches

Robert Fullick, MD  and David Doherty, MD 
Memorial Hermann-Texas Medical Center

Advances in shoulder arthroplasty have led to increased interest with more than 50,000 surgeries performed yearly in the United States. Choosing the appropriate surgical approach and meticulous soft tissue handling during surgery has a significant effect on patient outcomes. Less invasive, rotator cuff-sparing exposures continue to be developed and improved upon; however, “classic” glenohumeral approaches are still the most commonly used for shoulder arthroplasty. Here, we describe the different approaches available while highlighting relevant considerations for each.

Deltopectoral Approach

The patient is positioned supine with the head of the bed elevated 30⁰ to 60⁰ in the beach-chair position. The entire arm is draped free to facilitate positioning of the arm and improved exposure throughout the case. Bony landmarks should be palpated and marked prior to incision, including the acromion, clavicle, AC joint and coracoid. The incision begins just lateral to the coracoid process and extends distally along the deltopectoral groove 8cm to 10cm (Figure 1a).

Deltopectoral1med.jpgDeltopectoral2med.jpg

Figure 1a and 1b. Making the incision and careful exposure of the cephalic vein

The cephalic vein is identified coursing in the interval between the deltoid and pectoralis major. The vein is often obscured by a fat stripe and can be located beneath. Careful exposure of the vein allows for identification of tributaries that may be cauterized or ligated (Figure 1b). Surgeon preference dictates whether the cephalic vein is mobilized medially or laterally.

Once the deltopectoral interval has been developed, the conjoint tendon, comprised of the coracobrachialis and the short head of the biceps, is visualized originating from the tip of the coracoid process. The conjoint tendon is retracted medially after release of its lateral-most border. With the conjoint tendon mobilized, the subscapularis tendon is visualized inserting onto the lesser tuberosity of the humerus. At this time, the long head of the biceps tendon is localized just lateral to the subscapularis tendon insertion and sharply traced into the rotator interval. A biceps tenotomy and/or tenodesis may be performed.

The subscapularis tendon is either tenotomized 1cm medial to its insertion or an osteotomy is performed with the subscapularis tendon reflected with a wafer of bone from the lesser tuberosity. Once the subscapularis is retracted medially, the arm is externally rotated so that the humeral head may be dislocated anteriorly and exposed. Further release of the anterior and inferior capsule is carried out directly off the anatomic neck of the humerus to minimize risk of axillary nerve injury.

The humeral head is resected, which provides visualization of the glenohumeral joint. Further capsular releases may be performed to facilitate en face visualization of the glenoid. Final preparation of the joint may then proceed as appropriate components are selected and implanted.

There are several strengths to the deltopectoral approach. First, it is familiar to surgeons who perform shoulder surgery. Second, this approach is safe given that it is a truly internervous approach. Third, it provides excellent exposure of the glenohumeral joint and is an extensile approach when exposure of the humerus is necessary.

Weaknesses of this approach include limitations in exposure and reconstruction of the posterior joint and glenoid. Secondly, the risk of neurovascular injury exists with this approach. The brachial plexus, including the axillary and musculocutaneous nerves, is at risk during exposure, soft tissue dissection and errant retractor placement. The well-documented complication of subscapularis repair failure can lead to prosthesis instability and shoulder dysfunction. Despite these limitations, the deltopectoral approach remains the most widely used for shoulder reconstructive procedures, including arthroplasty.

Superolateral Approach

The patient is placed in the beach-chair position with the entire arm draped free to aid in exposure. Again, standard bony landmarks should be palpated and marked prior to incision. The incision begins over the AC joint and continues laterally over the acromion to its anterolateral border (Figure 2a). Here, the incision turns distally and continues down the long axis of the humerus.

Superolateral1med.jpgSuperolateral2med.jpg

Figure 2a and 2b. A 3-inch incision is typically all that is needed to comfortably perform the superolateral approach.  Preferably, the exposure on the humeral side should not extend more than 5cm beyond the lateral edge of the acromion.

Once dissection reaches the deltoid fascia, blunt dissection is used to identify the plane between the anterior and middle heads of the deltoid. The axillary nerve is located approximately 5cm distal to the lateral acromion, but its anatomic location may vary. During the approach, it should be palpated to identify its location. Great care is required, as this approach does not use an internervous plane, and dissection and vigorous retraction risk axillary nerve damage and denervation of the anterior deltoid (Figure 2b).

After splitting of the deltoid, the subacromial bursa and coracoacromial ligament are exposed and can be debrided. Further exposure may be obtained by subperiosteal dissection and release of the anterior deltoid from the acromion. With the anterior deltoid retracted, there is excellent exposure of the humerus, the supraspinatus, long head of biceps tendon, and superior most aspect of subscapularis tendon. The long head of biceps tendon may be tenotomized and tenodesed at this time. The rotator interval is opened, and the humerus is delivered through the interval to allow for humeral head resection. An axial force applied from the elbow with the shoulder in slight extension will aid in humeral head exposure. Once the humeral head cut is made, further anterior and inferior capsular releases may be accomplished and adequate exposure of the glenoid is obtained.

This approach offers the surgeon excellent glenoid exposure, particularly the superior and posterior aspects of the glenoid. Patient positioning is similar to other approaches to the shoulder, and it represents an alternative to the deltopectoral approach for reverse shoulder arthroplasty. In addition, it provides excellent visualization of the entire rotator cuff and does not disrupt intact portions of the cuff.

It is a less extensile exposure, which can be a limitation when compared to the deltopectoral approach. In addition, difficulty with exposure and removal of inferior osteophytes from the anatomic neck of the humerus can be encountered. Further drawbacks include risk of axillary nerve damage and failure of the deltoid repair after release from the anterolateral acromion. These may lead to poor patient outcomes. This approach may also lead to an increased risk of glenoid component malpositioning, i.e., superior tilt of the glenoid baseplate, and loosening of glenoid components, especially in reverse shoulder arthroplasty.

Rotator Cuff Sparing Approach

The patient is placed in the beach-chair position. The author prefers elevating the head to 70deg, which is more vertical compared to standard total shoulder arthroplasty. All bony landmarks should be palpated and marked prior to incision. The incision begins 1-2cm lateral to coracoid tip. This may aid in visualization of the rotator interval and glenoid to follow. The superficial and intermediate portions of the dissection are similar to the deltopectoral approach. The cephalic vein is identified and retracted. The conjoint tendon is identified and retracted medially. A sharp Homan retractor is placed superior to the coracoid process and the CA ligament is often incised improving exposure of the rotator interval.

CuffSparing-Animation.gif

Figure 3. Detailed operative technique

The rotator interval is excised and a biceps tenotomy is completed. The tenodesis may be performed at the surgeon’s discretion. The subscapularis is then exposed in its entirety, and the leash of vessels at its inferior border is ligated. The inferior most portion of the subscapularis muscle belly is released and elevated from the humerus starting just superior to the vessels. This creates a window that provides the exposure necessary for an adequate capsular release and removal of inferior osteophytes from the humeral head. The capsule is released from anterior to posterior with progressive shoulder flexion and external rotation to provide inferior exposure. Care is taken to palpate the axillary nerve to define its location and course.

Attention is turned to exposure of the humeral head through the rotator interval. Retractors are placed beneath the supraspinatous along the posterior humeral head and deep to the subscapularis along the anterior anatomic neck to expose the humeral head through the interval. Adduction, extension, and external rotation bring the humeral head into the rotator interval for exposure and resection. Once the humeral head is resected, the humerus is prepared in standard fashion and further inferior and anterior capsular releases are performed. Retractors are repositioned allowing for glenoid completion. Lastly, the humerus is trialed and implanted through the rotator interval. The rotator interval is closed with interrupted sutures. The inferior subscapularis and capsule are not repaired (Figure 3).

This technique uses several features of the deltopectoral approach, and the anatomy is familiar. This is a muscle sparing approach that minimizes subscapularis tendon damage, hopefully leading to fewer subscapularis complications post-operatively compared to tenotomy or osteotomy. This allows for early active shoulder motion with less risk of subscapularis failure. Additionally, there is less extreme positioning of the arm in external rotation and abduction that may pose less risk of stretch injury to the axillary nerve and brachial plexus during glenoid exposure.

This approach is associated with a steep learning curve. Poor exposure can cause component malpositioning and specials retractors may be required for adequate visualization. Currently, this technique should be performed by experienced shoulder surgeons. It is best suited for primary arthroplasty without excessive glenoid erosion or bony deformity.

Conclusion

Shoulder arthroplasty techniques continue to evolve. Soft-tissue-sparing approaches including rotator cuff sparing and transhumeral techniques continue to advance. Ultimately, the goals of current research are improved patient outcomes and implant survivorship. Before each surgery, the surgeon should consider relevant anatomy and pathology and choose the approach that provides highest likelihood for success.

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Does Direct Anterior Approach Require a Specialized Table? How to Perform this Cost-Effective Approach without Additional Equipment

Barton Harris, MD
OrthoVirginia

The direct anterior approach for total hip arthroplasty has been gaining favor with surgeons and patients alike in the last several years. A true internervous approach, it offers the potential advantages of decreased muscle injury, accurate component positioning, low dislocation rate and faster early recovery. While long-term follow-up results appear to show the expected excellent outcomes similar to other traditional approaches, the direct anterior approach may facilitate shorter length of stay and return to work and activities for patients.

Most surgeons find that initial exposure of the hip joint is quite easy, regardless of whether the surgeon uses a special table or not. The acetabular exposure affords direct visualization and ready in-line access for reaming and broaching. Femoral exposure, however, can be challenging, particularly in learning curve. The majority of hip surgeons using the anterior approach use some form of specialized operating table or attachment to make this exposure more facile. This specialized equipment allows the leg to be maximally extended and adducted to gain access to the femoral canal.

Specialized table vs. regular operating room table

The specialized tables, while useful for many, can have some disadvantages. These tables are expensive, often costing in excess of $100,000. A smaller hospital may not have the resources to purchase a table, and larger facilities may be unwilling to buy more than one, making running more than one operating room at a time for hip replacement difficult. These tables also require a trained assistant to manipulate the leg rather than leaving the control of the limb in the hands of the surgeon. These devices can exert tremendous forces, and there have been rare reports of ankle fractures­­—and more common reports of trochanteric fractures— as a result. Traction nerve palsies have also been reported. The table itself is quite large and may be difficult to use in smaller operating rooms.

We prefer the use of a regular operating room table for the direct anterior approach. This requires no additional equipment and may be performed in any size operating room. It facilitates easy patient positioning and allows simultaneous bilateral procedures. Direct comparison of leg lengths and range of motion / stability assessment are easily performed, as the limb is draped free. The surgeon maintains control of the limb making iatrogenic fracture less likely. The table is positioned with the base of the table toward anesthesia and the head of the bed moved to the foot (Figure 1). This allows ample room for fluoroscopy and positions the patient so that the break in the table can facilitate extension of the hip. A gel pad can also be utilized to further assist. The patient is positioned so that the gluteal fold is at the break in the table, which is then used as a fulcrum to elevate the femur (Figure 2).

Figure 1

 Figure 1. Table set up

DAA Positioning

Figure 2. Patient positioning

Incision and femoral exposure

The direct anterior approach has been described in detail in other publications. The approach is performed in the internervous Smith-Peterson interval. The incision usually begins three fingerbreadths distal and lateral to the ASIS to avoid the lateral femoral cutaneous nerve and is carried distally, centered over the greater trochanter (Figure 3). The superficial fascia of the TFL is incised and a finger bluntly swept over the muscle medially.

DAA Incision

Figure 3. Where to begin the incision

Lateral mobilization of the Tensor is greatly facilitated by incising the deep fascia of this muscle longitudinally. Retractors are placed above and below the femoral neck outside the capsule. A retractor placed deep to the Tensor and lateral to the trochanter can be helpful. The vascular leash of the circumflex vessels is identified and cauterized or ligated. A retractor is placed anteriorly over the acetabulum and gentle release of the iliocapsularis and reflected head of the rectus is performed. Use caution that the anterior retractor is placed directly over the acetabulum and that the assistant does not rotate the retractor on its side, potentially tenting the femoral nerve over the edge of the retractor. Capsulotomy is performed and retractors placed inside. Femoral neck osteotomy may be performed in a single cut or a “napkin ring” fashion, using the saddle as a reference point based on preoperative x-rays. There can often be a sharp edge on the cut surface of the femoral head. Be sure that this does not damage the fibers of the Tensor during removal as this muscle injury can propagate over the course of the procedure. A small incision in the posterior capsule allows posterior retractor placement to depress the femur during acetabular preparation. An inferior retractor allows ready access for reaming and visualization of the transverse acetabular ligament for reference (Figure 4). Once the acetabular component has been placed, exposure of the proximal femur is performed (Figure 5).

DAA Retractors

Figure 4. Retractor placement

DAA Femoral Exposure

Figure 5. Femoral exposure

Release and stability

The table is placed in slight Trendelenburg position, and the leg of the bed flexed slightly. The leg is maximally externally rotated and adducted. A retractor is placed medially on the calcar, and a bone hook is inserted into the cut surface. This bone hook is used to pull the femur laterally before elevating the femur with a retractor placed behind the trochanter. This critical maneuver ensures that the trochanter is not behind the acetabulum during attempted elevation and avoids trochanteric fracture. Capsular release is performed in a stepwise fashion (Figure 6). The superior capsule may be safely elevated from the entire interior surface of the trochanter. It has been well demonstrated that the abductors insert laterally and are not in danger during this release. Occasionally the piriformis is released, but avoid any further distal release for improved stability.

Figure 6. Capsular release

Maintaining the posterior structures also makes it difficult to over-lengthen the leg. A large retractor placed behind the trochanter is used to gently elevate the proximal femur. A curved canal finder is recommended to sound the canal to ensure that the trajectory of the broach is appropriate and does not violate the lateral cortex. Routine broaching is performed. Single- or double-offset broaches can make this easier, but beware that an offset broach can introduce torque on the broach, and the surgeon should use caution to maintain the same degree of anteversion. It is often helpful to obtain a fluoroscopic image with one of the early broaches to get a sense of where work needs to be done with subsequent broaches. Reduction should be relatively easy with traction and internal rotation. Lengths may be checked both clinically and radiographically. Stability is checked anteriorly in maximal external rotation with the hip extended as well as posteriorly in hip flexion with internal rotation (Figure 7). Following final implantation of components, simple closure of the superficial fascia of the TFL followed by periarticular injection is performed. Routine skin closure and dressing of choice completes the operation. No postoperative abduction pillow or hip precautions are used.

DAA Stability

Figure 7. Stability check

Conclusion

As with any technique new to a surgeon, it is highly recommended that as much education as possible be done before using the technique on patients. This can be done through surgery observation, cadaver courses, and review of literature and available video presentations. Easier cases are on slender patients with low muscle mass and high femoral offset. With experience, it is possible to perform this approach without difficulty on all patients. While the learning curve can be steep, for most surgeons the direct anterior approach becomes a preferred approach once familiar.

If you’re ready to observe surgery using this approach with Dr. Harris, today.

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The Effect of Posterior Tibial Slope on the Kinematics of PCL-Retaining TKA: A Pilot Study Using a Novel, Soft-Tissue Preserving Test Method

 Jean-Yves Jenny, MD
Hôpitaux Universitaires de Strasbourg
Michael B. Cross, MD
Hospital for Special Surgery

Introduction

Abnormal knee kinematics have been found in fluoroscopy studies after total knee arthroplasty (TKA)1, which may lead to suboptimal clinical outcomes2. For cruciate-retaining (CR) TKA, the posterior tibial slope (PTS) of the reconstructed proximal tibia has been theorized to play a significant role in restoring normal knee kinematics as it directly affects the tension of the posterior cruciate ligament (PCL)3,4. Thus, the need for a deeper understanding of the impact of PTS has driven current research on the postoperative kinematics of the CR knee, which traditionally has been carried out by conventional cadaveric testing. However the reproducibility of such cadaveric testing may not be acceptable, as repetitive changes of the PTS due to removal of trial implants from cadaveric bone may damage the soft tissues in the knee. Although some soft tissue preserving methods have been proposed for the adjustment of the PTS, such as performing an anterior opening wedge osteotomy and filling the gap with bone cement4, these proposed methods may lead to inaccuracy in PTS, as results can be affected by variability when performing the osteotomy and/or cement curing.

In this present study, a novel, soft-tissue preserving method for measuring the effects of PTS on the knee kinematics was developed and verified. A preliminary analysis was performed on one cadaveric knee to assess the impact of PTS on the kinematics of a CR TKA.

Materials and Methods

A cemented CR TKA (Optetrak Logic® CR, Exactech, Gainesville, FL) was performed using a computer-assisted surgical guidance system (ExactechGPS®, Blue-Ortho, Grenoble, FR) on one fresh-frozen non-arthritic cadaveric knee with an intact PCL. The tibial baseplate was custom designed with a mechanism to precisely and easily modify the PTS without the need to repeatedly remove and assemble tibial inserts of varying posterior slopes (as offered by the Optetrak Logic CR system) (Fig. 1). Postoperative tibiofemoral internal/external (I/E) rotation, tibiofemoral anteroposterior (AP) translation, and hip-knee-ankle angles (HKA) were evaluated by performing a full passive range of motion (ROM) (flexion angle from 0° to 120°) three separate times at each of the five experimental PTSs in the following order: 10°, 7°, 4°, 1°, and back to 10° at the end of the testing. The novel test method with the custom designed tibial baseplate was verified by assessing any potential damage of the PCL or other soft tissues by comparing the kinematic data of the initial and the last experimental conditions at 10° PTS. Statistical comparisons were performed at ~0° (3°), 30°, 60°, 90° and 120° flexion angles. The kinematics were then also compared across PTSs for the specific knee investigated (the first 10°, 7°, 4°, and 1°). Statistical significance was defined as p < 0.05.

Knee Fig 1

Figure 1: A custom designed tibial baseplate for the test. Turning the anterior screw (1) results in modification of the posterior tibial slope (2).

Results

Test method verification
Similar knee kinematics were observed between the two sets of data acquisitions at 10° PTS (Fig. 2), with the tibiofemoral AP translation being nearly identical. No significant differences were found between the two sets of data at the sampled flexion angles, except for an arguably clinically negligible difference in the tibiofemoral AP translation at 30° flexion (p = 0.04, difference in means <1mm).

Impact of PTS on knee kinematics
All four PTSs generally had similar kinematic patterns across all flexion angles. However, clinically significant changes in the normal tibiofemoral I/E rotational kinematics were found for PTSs of 1° and 4°, while PTSs of 7° and 10° led to I/E rotational kinematics close to the normal knee (Fig. 3A). Similar AP kinematics were found between the native knee and all four PTSs (Fig. 3B). All PTSs closely follow the same pattern in HKA, which was different than the native knee (Fig. 3C). However, the differences in HKA may not be clinically significant (less than 2°-3°).

Knee Fig 2 ABC

Figure 2: A) tibiofemoral I/E rotation, B) HKA, and C) tibiofemoral AP translation as a function of the flexion, compared between the initial and the last acquisitions at 10° PTS.

Knee Fig 3 ABC

Figure 3. Comparison of A) tibiofemoral I/E rotation, B) tibiofemoral AP translation, and C) HKA between the native knee and the component implanted at different PTSs.

Discussion

This pilot study demonstrated that the novel test method developed does not significantly disrupt the soft tissue environment of the knee. Previous evaluations of the effect of the PTS on passive knee kinematics often manipulate the PTS by re-cutting the proximal tibia and/or frequently exchanging the tibial insert, which has been shown to damage the PCL and/or stretch the soft tissue envelope5. As a result, those studies may have inherent flaws that prevent meaningful data collection. The novel tibial baseplate designed for this study adjusts the PTS without re-cutting the tibia and removing the components, therefore offers a reliable test method that respects the soft tissue envelope in the knee.

The preliminary results presented here showed that PTS can impact the kinematics in the knee. For the specific knee and implant design investigated, the impact of the PTS was explicit in the tibiofemoral I/E rotation and AP translation, which may be related to the strain in the PCL. In contrast, PTS impacted the HKA to a lesser degree.

Based on this pilot study, the authors recommend the proposed test method for future investigations on the effect of PTS on the postoperative knee kinematics.


References

1. Banks SA, Markovich GD, Hodge WA. In vivo kinematics of cruciate-retaining and-substituting knee arthroplasties, J Arthroplasty,12, pp: 297-304, 1997.
2. D’Lima DD, Hermida JC, Chen PC Colwell CW Jr. Polyethylene wear and variations in knee kinematics, Clin Orthop Relat Res, 392, pp: 124-130, 2001.
3. Conditt M. The effect of posterior tibial slope on the kinematics of PCL-retaining TKA, J Bone Joint Surg Br, 86-B, SUPP I, 17, 2004.
4. Giffin JR, Vogrin TM, Zantop T, Woo SLY, Harner CD. Effects of increasing tibial slope on the biomechanics of the knee, Am J Sports Med, 32(2), pp: 376-382, 2004.
5. Shannon FJ, Cronin JJ, Cleary MS, Eustace SJ, O’Byrne JM. The posterior cruciate ligament-preserving total knee replacement: do we ‘preserve’ it? A radiological study, J Bone Joint Surg Br, 89(6), pp: 766-771, 2007.

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Exactech Announces Full Launch of Three Revision Systems and Expansion of Advanced Surgical Technologies at AAOS 2017 Annual Meeting, Exhibit #1433

GAINESVILLE, Fla. (March 13, 2017) – Exactech (Nasdaq: EXAC), a developer and producer of bone and joint restoration products and biologic solutions for extremities, knee and hip, announced today its lineup of products to be showcased at the company’s educational exhibit, Booth #1433, at the American Academy of Orthopedic Surgeons (AAOS) 2017 Annual Meeting, March 15-17 in San Diego, Calif.

Highlights of Exactech’s latest innovations include:

  • ExactechGPS®, a compact, surgeon-controlled computer-assisted surgical technology that delivers reproducible results in total joint arthroplasty, expands its offerings with new knee applications, as well as the first application for total shoulder arthroplasty.* Live demonstrations will take place throughout the event.
  • The Equinoxe® Humeral Reconstruction Prosthesis offers a unique and stable solution for complex and challenging shoulder arthroplasty cases with significant humeral bone loss.** Also featured will be the new Preserve Stem, a conservative treatment option designed for preserving humeral bone.
  • The Vantage® Total Ankle System is Exactech’s first product in the foot and ankle market. The system features both tibial and talar components, which were designed for minimal bone resection and optimal support for the anatomically shaped implant.
  • The Optetrak Logic® CC Revision Knee System offers a comprehensive portfolio to help surgeons address challenging revision cases. Exactech’s redesigned, intuitive instrumentation for an efficient, streamlined surgical experience will also be showcased.
  • The Alteon® Monobloc Revision Femoral Stem is a press-fit, distally fixed, one-piece tapered, splined titanium stem. It incorporates specific philosophies designed to improve surgical experiences and clinical outcomes for hip arthroplasty patients.
  • The InterSpace® Tapered Wedge Hip Spacer and data behind InterSpace’s preformed spacer technology with 20 years of clinical experience will be showcased. The AcuDriver® Automated Osteotome Handpiece for implant removal will be featured in live demonstrations.
  • Ossilix® is a high performance, next generation calcium phosphate cement indicated for filling bony defects in cancellous bone. Ossilix is fast- and hardsetting within approximately six minutes in a 37°F wet environment. Once set, it can be drilled and inserted with screws. In addition, the Biologics offerings will include Reveille™ Cartilage Processor, a cost effective option for single stage surgery with autologous cartilage. Reveille is used for intra-operative resizing of autologous tissue into usable particles.

Exactech will showcase new clinical data in the Journal of Shoulder and Elbow Surgery Compendium of Shoulder Outcomes and Research and Exactech Knee Scientific and Clinical Evidence booklet. Scientists and surgeon consultants will be available to discuss the articles, as well as share their experiences on all of the company’s latest product innovations. Attendees may also learn about Exactech’s patient education and practice marketing program at the booth.

Visit staging.exac.com/academy for more information on featured products, scheduled clinical experts and live demonstrations.

*The ExactechGPS Total Shoulder Application is currently undergoing premarket review by the FDA. It is intended for use during preoperative planning and during stereotaxic surgery to aid the surgeon in locating anatomical structures and aligning the endoprostheses with the anatomical structures.

**The Equinoxe Humeral Reconstruction Prosthesis is not indicated for use with the reverse shoulder components in oncology applications.

About Exactech

Based in Gainesville, Fla., Exactech develops and markets orthopaedic implant devices, related surgical instruments and biologic materials and services to hospitals and physicians. The company manufactures many of its orthopaedic devices at its Gainesville facility. Exactech’s orthopaedic products are used in the restoration of bones and joints that have deteriorated as a result of injury or diseases such as arthritis. Exactech markets its products in the United States, in addition to more than 30 markets in Europe, Latin America, Asia and the Pacific. Additional information about Exactech can be found at https://staging.exac.com.

Investor contacts

Jody Phillips
Executive Vice President of Finance & Chief Financial Officer
352-377-1140

Julie Marshall or Frank Hawkins
Hawk Associates
305-451-1888
EXAC@hawkassociates.com

Media contact

Priscilla Bennett
Vice President, Corporate & Marketing Communication
352-377-1140

Data in Brief: Treating Infected Joints

LOW-DOSE GENTAMICIN-LOADED SPACERS ARE EFFECTIVE FOR TWO-STAGE REVISION
Romano CL, Drago L, Logoluso N.
Musculoskeletal Infection  Society (MSIS). 2013 July 30.

SUMMARY Peri-prosthetic infection is among the most common reason for revision in the United States and in Europe. Two-stage revision with antibiotic-loaded spacers is the gold standard with an eradication rate greater than 90 percent. High antibiotic concentration (greater than 2 percent) and the association of more than one antibiotic in the spacer are proposed by different authors in a limited series of patients.

MATERIALS AND METHODS A systematic review of published papers on two-stage revisions of infected total hip and knee arthroplasties treated with the routine use of an industrial low-dose (1.9 percent) gentamicin-loaded, preformed spacer has been performed. This systematic review evaluated the hypothesis: are high antibiotic concentrations and antibiotic associations necessary for interim spacers in routine two-stage revision surgery? Papers that were included were published in peer-reviewed journals from the years 1995 to 2013 and reported an infection eradication rate of two-stage hip or knee joint prosthesis with the use of an industrial, preformed low-dose gentamicin spacer (Spacer G or Spacer K, Tecres SpA, Italy. InterSpace® Hip or InterSpace Knee, Exactech, Inc. USA). The systematic review excluded case reports, clinical series with less than 10 patients, duplicate studies and mean follow-up less than 24 months.

RESULTS Twenty-four papers were retrieved, 10 of which met the inclusion criteria, yielding a total of 491 spacers implanted in10 centers (seven in Europe, two in North America and one in Oceania). Nineteen patients (3.9 percent) had an infection recurrence/persistence that required a spacer exchange or are section arthroplasty.

Twenty-five of the 480 patients (5.2percent) that underwent the second stage procedure had an infection recurrence/persistence at an average follow-up of 46 months.

KEY QUOTE “This systematic review provides evidence in favor of the routine use of an industrially, preformed spacer loaded with a standardized, relatively low concentration of gentamicin,[and] that in different centers, showed an average infection eradication rate of 96.1 percent at spacer removal and 94.8percent at the latest follow-up after re-implantation. The systematic review does not support the hypothesis that the antibiotic associations or antibiotic concentrations higher than1.9 percent are routinely needed for spacers used in two stage revision surgery.”


MEASUREMENTS OF IN-VIVO INTRA-ARTICULARGENTAMICIN LEVELS FROM ANTIBIOTIC-LOADED ARTICULATING SPACERS IN REVISION TOTAL KNEE REPLACEMENT
Mutimer J, Gillespie G, Lovering AM, Porteous AJ.
Knee. 2009 Jan;16(1):39-41. doi: 10.1016/j.knee.2008.07.009. Epub 2008 Sep 10.

SUMMARY Previous in-vitro studies have found high levels of antibiotic release in the days immediately following implantation of antibiotic-loaded, articulating spacers. However, there is relatively little data describing the elution profile beyond this immediate period. This study was designed to measure if gentamicin levels continue to be clinically therapeutic after an extended period following in-vivo implantation.

MATERIALS AND METHODS Twelve patients received a gentamicin-loaded, articulating spacer between a first- and second-stage revision total knee arthroplasty. At the second stage procedure, synovial fluid and blood samples were collected and assayed for the presence of gentamicin. The second-stage revision occurred at a median of 99 days following the spacer insertion.

RESULTS The median intra-articular gentamicin levels were 0.46 mg/L (0.24 to 2.36 mg/L), which would be considered therapeutic. There were no cases of re-infection.

CONCLUSIONS In this study, preformed articulating spacers containing gentamicin provided therapeutic concentrations in the synovial fluid surrounding the joint throughout the period of implantation. This data confirms the observations from in-vitro studies where a prolonged elution profile was observed for such spacers (Spacer K, Tecres SpA, Italy. InterSpace Knee, Exactech, Inc. USA).

KEY QUOTE “It is therefore interesting to see potentially therapeutic levels of gentamicin at an average of 99 days post insertion of the spacer suggesting that good antibiotic levels are maintained around the spacer for most of the time it is in position.”


TREATMENT OF THE GLENOHUMERAL SEPSIS WITH A COMMERCIALLY-PRODUCED, ANTIBIOTIC-IMPREGNATEDCEMENT SPACER
Coffey MJ, Ely EE, Crosby LA.
J Shoulder Elbow Surg. 2010 Sep;19(6):868-73. doi: 10.1016/j.jse.2010.01.012. Epub 2010 Apr 14.

SUMMARY This study evaluated treating an infected shoulder arthroplasty and primary shoulder sepsis using a commercially-produced, antibiotic-impregnated cement spacer.

MATERIALS AND METHODS Sixteen shoulders in 15 patients with infected arthroplasty or osteomyelitis of the proximal humerus were treated with irrigation and debridement; hardware removal, humeral head resection, or both; and placement of an interval articulating hemiarthroplasty with a commercially-made, gentamicin-impregnated cement spacer (InterSpace Shoulder, Exactech, Inc. USA).

RESULTS The mean follow-up was 20.5 months after spacer placement. At the time of debridement, 12 shoulders had positive cultures; the most common organisms were methicillin-resistant Staphylococcus aureus (n = 3) and S. epidermidis (n= 3). Twelve patients underwent revisions while four refused revisions and have retained antibiotic spacers. There was no recurrence of infection.

CONCLUSIONS Treatment of glenohumeral sepsis with a commercially-produced, antibiotic-impregnated cement spacer appears to be an effective treatment modality and serum interleukin-6 levels appear to be useful in the evaluation of shoulder infection.

KEY QUOTE “The incidence of reinfection in our series of 16 infected shoulders was zero, whereas the incidence in other series of infected shoulders treated with staged revision arthroplasty with an antibiotic spacer ranges from 0 to 40 percent. In addition to absence of reinfection, patients in our series demonstrated clinical improvements with regards to visual analog pain scale, range of motion, and other subjective and objective shoulder evaluation scores.”


PREFORMED ARTICULATING KNEE SPACERS IN TWO-STAGE TOTAL KNEE ARTHROPLASTY: MINIMUM TWO-YEAR FOLLOW-UP
Wan Z, Karim A, Momaya A, Incavo SJ, Mathis KB.J Arthroplasty. 2012 Sep; 27(8):1469-73. doi: 10.1016/j.arth.2012.01.027. Epub 2012 Mar 14.

SUMMARY Two-stage revision arthroplasty using articulating spacers for the treatment of infected total knee arthroplasty (TKA) is a successful management technique. Our purpose was to report our results using preformed, commercially-available articulating spacers made of gentamicin-impregnated cement (Spacer K, Tecres S.p.A. Italy. InterSpace Knee, Exactech, Inc.USA).

MATERIALS AND METHODS Thirty-three patients with an infected primary or revision TKAs were treated with these spacers using a two-stage revision technique. In most cases, the spacers were modified intraoperatively by adding a stem of reinforced antibiotic-impregnated acrylic cement.

RESULTS Successful eradication was achieved in 30 of 33 cases at a minimum two-year follow-up interval. Two patients required a second spacer before a successful TKA revision. No spacer fractures or dislocations occurred in this series. No adverse soft tissue effects were noted from the use of this type of articulating spacer.

KEY QUOTE “Our lower eradication rate (91 percent) compares favorably with other reports even with the inclusion of more complex cases involving multiple previous surgeries, resulting in longer times of active infection as well as compromised bone and soft tissue.”


DOES A PREFABRICATED, GENTAMICIN-IMPREGNATED, LOAD BEARING SPACER CONTROL PERIPROSTHETIC HIP INFECTION?
Degen RM, Davey JR, Davey JR, Howard JL, McCalden RW, Naudie DD.
Clin Orthop Relat Res. 2012 Oct;470(10):2724-9. doi: 10.1007/s11999-012-2350-3.

SUMMARY Treating deep infection following THA has been a challenge. While the standard treatment has remained a two-stage revision, spacer designs, incorporated antibiotics and concentrations have varied. Since control of infection may relate to the choice and concentration of antibiotics, it is important to report rates of control from various spacers. This study determined the rate of infection control and complications associated with a prefabricated, load bearing, gentamicin-impregnated hip spacer (Spacer G, Tecres S.p.A. Italy. Inter-Space Hip, Exactech, Inc. USA) in treating per prosthetic hip infections.

MATERIALS AND METHODS Thirty-three patients with periprosthetic THA infections were retrospectively reviewed and treated with a prefabricated, partial load bearing, gentamicin-impregnated hemiarthroplasty spacer. Thirty of the 33 patients underwent second-stagere implantation after a mean of 15 weeks. Patient demographic data; laboratory values; infecting organism; size of spacer; antibiotic selection; complications; and infection control rates from two academic centers were collected. Recurrent infection at last follow-up was determined by the presence of physical symptoms or signs or elevated serologic tests. The minimum follow-up was 24 months (mean- 43 months; range- 24–70 months).

RESULTS Twenty-eight of the 30 patients who underwent reimplantation remained infection free at last follow-up. One patient became reinfected with a different organism secondary to wound problems. Another became reinfected with the same organism, but was restaged with the prefabricated spacer used in this study, reimplanted, and subsequently remained free of infection. Two of the 33 patients had persistently elevated inflammatory markers at the completion of the first stage and were restaged with this spacer. Both underwent reimplantation and remained free of infection at latest follow-up. One of the 33 patients was satisfied and ambulatory with their spacer. There were no major complications.

CONCLUSIONS Overall, the data supports the use of a partial load bearing, gentamicin-impregnated hemiarthroplasty spacer in treating deep periprosthetic THA infections.

KEY QUOTE “In the end, infection control was ultimately achieved in 3 2of 33 (97 percent) patients.”

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Literature Review: Observations on Proximal Humerus Fractures

Gregory Gilot, MD
Cleveland Clinic Florida

LOCKING PLATE FIXATION OF FRACTURES OF THE PROXIMAL HUMERUS: ANALYSIS OF COMPLICATIONS, REVISION STRATEGIES AND OUTCOMES

TO REVIEW IS TO OPINE It appears that the large majority of patients who present with complications following locking screw ORIF are those with a high likelihood of vascular disruption of the humeral head (four-part fractures, short metaphysical segment) at the time of injury. While the risks of vascular necrosis, varus collapse with secondary screw cut out are relatively high, under the age of 60 years in patients with adequate bone stock a joint preserving procedure should be attempted. Failure of locking screw ORIF can be recognized as early as nine months and the secondary treatment entertained.

 SUMMARY The purpose of the study was to report the complications, their treatment and outcome of 121 patients referred after primary locking plate ORIF for proximal humerus fractures. The authors recognized the increasing numbers of complications following such surgeries being referred to the tertiary referral center. Among the known complications of AVN, varus collapse and screw cutout being reported, the previously unknown complication of iatrogenic glenoid destruction due to perforated head screws was reported.

 MATERIALS AND METHODS One hundred twenty one patients with complications we recollected. Sixty-seven patients were women and 54 were men. The mean age at initial injury was 59 years. All 121patients were treated with the PHILOS plate (Synthes, Paoli, PA, USA). Of the 114 classified fractures, 17 were 2-part, 373-part, and 60 4-parts. All patients presented with restricted function and pain and were seen after a mean of 15 months after index ORIF.

RESULTS A mean of three complications occurred per patient.

Complication

Number ofpatients (%)

Malreduction 67 (55%)
Primary screw cutout 14 (12%)
Malunion 76 (63%)
Nonunion 16 (13%)
AVN 82 (68%)
Infection 5 (4%)
Secondary screw cutout 69 (57%)
Glenoid destruction 40 (33%)

TREATMENT AND OUTCOMES One hundred seven (88 percent) patients underwent revision surgery. A mean of 1.5 surgeries were performed per shoulder. Partial and total hardware removals were the most common revision operations in this study. Overall, over 50percent of patients finally needed secondary arthroplasty.

Treatment

Secondary
Arthroplasty

Re-osteosynthesis              8 3
Arthroscopy                      10 3
Partial hardware removal 16 7
Total hardware removal   41

17

Secondary arthroplasty    61

CONCLUSIONS In this collective of patients with complications following locking screw ORIF, 50 percent had four-part fractures, 20percent were head splitting or fracture-dislocations, and 80percent had no metaphysical segment attached to the head. These factors are known to be associated with poorer outcomes underscoring that the primary surgery should be definitive if possible. Lastly, Neither secondary hemiarthroplasty, total shoulder arthroplasty or reverse total shoulder arthroplasty yielded results comparable to primary arthroplasty. •


REVERSE SHOULDER ARTHROPLASTY VERSUS HEMIARTHROPLASTY FOR ACUTE PROXIMAL HUMERUS FRACTURES.  A BLINDED, RANDOMIZED, CONTROLLED, PROSPECTIVE STUDY 

TO REVIEW IS TO OPINE While the radiographic outcomes in terms of tuberosity healing appear comparable, it is the differences in clinical outcomes, forward flexion and revision rate that would lead the reader to believe that rTSA is superior to HA for the treatment of proximal humeral fractures in the elderly. Forward flexion results appear to be independent of tuberosity healing with a predictable low number of patients who do not achieve a minimum of 90 degrees forward flexion following an rTSA. Implant survival is superior for rTSA when compared to HA.

 SUMMARY The surgical treatment of complex proximal humerus fractures in the elderly with poor quality bone remains controversial. These factors negatively impact the results of internal fixation and hemiarthroplasty (HA) has been considered a good surgical option in these patients. Reverse shoulder arthroplasty (rTSA) has the theoretical advantage of independence of tuberosity healing and rotator cuff integrity. Useful clinical conclusions and clear guidelines for treatment currently do not exist. The aim of this study was to compare the outcomes of rTSA and HA for acute proximal humerus fractures in elderly patients.

MATERIALS AND METHODS This blinded, randomized, controlled prospective study included patients 70 years or older whose complex fractures were not amenable to reconstruction. To avoid selection bias patients found to have irreparable cuff tears were not excluded. Sixty-two patients were randomized to rTSA (31) and HA (31). The mean follow-up was 28.5 months. The modular shoulder replacement system (SMR; Lima, Udine, Italy) was used in both groups. Surgery was performed similarly in both groups. Tuberosities were handled identically. Postoperative regimens were similar in both groups. In the HA group, a rotator cuff tear was found in 11 cases; in three cases the tear was irreparable. In the rTSA group, a rotator cuff tear was found in 14 cases; in five cases the tear was irreparable. Clinical evaluation included the Constant-Murley score, theUCLA score, the DASH score, range of motion and strength. Radiographic evaluation included the status and position of the tuberosities, implant loosening, proximal migration in the HA group and inferior scapular notching in the rTSA group.

 RESULTS
There were no statistically preoperative differences between the groups.

Outcome rTSA Group HA Group
Constant score (p=0.001) 56.1 40.0
UCLA score (p=0.001) 29.1  

21.1

DASH score (p=0.001 17.5 24.4
Forward flexion (p=0.001) 120.3 79.8
Forward flexion <90 degrees 1 (3.2%) 10 (33.3%)
External rotation (p=0.023) 4.7 3.3
Internal rotation (p=0.914) 2.7 2.6
Tuberosity healing 20 (64.5%) 17 (56.7%)
Tuberosity resorption 5 (16.2%) 9 (30.0%)
Revisions 1 6
40-month implant survival 96.8% 80.0%

 CONCLUSIONS In this study, rTSA was superior to HA with respect to pain, functional outcome, and revision rate. While forward flexion and abduction were significantly better in the rTSA group there was no significant difference in internal rotation. There was one (3.2 percent) case of scapular notching observed. The six revisions within the HA group were due to proximal migration resulting in severe pain and limited function. There was one deep wound infection within the rTSA group requiring a two-stage revision. All revised patients suffered poor Constant scores and unsuccessful functional outcomes. Revision from HA to rTSA did not appear to improve outcomes. •

 


REVERSE SHOULDER ARTHROPLASTY FOR THE TREATMENTOF THREE- AND FOUR-PART FRACTURES OFTHE PROXIMAL HUMERUS IN THE ELDERLY. A PROSPECTIVE REVIEW OF 43 CASES WITH SHORT-TERM FOLLOW UP

 TO REVIEW IS TO OPINE The management of complex proximal humeral fractures in the elderly continues to be a difficult problem to solve with a predictable solution. This study is one of the first to report short term results. What is well demonstrated is the need for reliable tuberosity reconstruction to optimize outcomes. These conclusions argue strongly for disease specific implants that allow for anatomical tuberosity.

SUMMARY The use of reverse shoulder arthroplasty in complex proximal humerus fractures cannot be routinely recommended due to the paucity of clinical studies. While mid-term results appear to be encouraging, to date its use in trauma has been described in only small series. The aim of this study was to describe the author’s experience with this technique in the short term in elderly patients.

 MATERIALS AND METHODS Forty-three patients with a mean age of 78 years with an acute proximal humerus fracture were treated with a Delta reversed shoulder prosthesis (Depuy, Saint Priest, France).Operative treatment and post-operative care were similar for all patients. While the tuberosities were repaired, the supra-spinatus, when present, was divided and removed. Mean follow-up was 22 months. Clinical outcomes included Constant and Murley score, the ASES score, the DASH score, and mobility. Radiographic evaluation included recording inferior scapular notching, assessing the position of the centre of the shoulder, the glenoid inclination angle, heterotopic ossification and healing of the tuberosities.

RESULTS Complications occurred in 12 patients. While greater tuberosity healing did improve external rotation this was not significant. The shoulder centre medialization had a mean of 21mm and a mean of 9mm below the centre of rotation of the contralateral side. Patients with a lower center had better results but this difference was not significant. Of the scapular notching that was observed, only one was Sirveaux grade 3.

Clinical & Radiographic Outcomes rTSA Group
Constant score 44
ASES score 9
DASH score 44
Anterior elevation 97
External rotation 8
Tuberosity displacement 19 (53%)
Tuberosity malunion 5 (13.8%)
Tuberosity nonunion 14 (3.8%)
Scapular notching 10 (25%)
Glenoid component inclination 15 degrees
Shoulder center medicalization 21mm
Heterotopic ossification 36 (90%)

 CONCLUSIONS In this study, satisfactory mobility was obtained with the use of a reversed shoulder arthroplasty in complex proximal humerus fractures despite a 53 percent rate off displacement of the tuberosities. When anatomical reconstruction of the tuberosities was achieved (41.5 percent) the effect on the Constant score appeared to be moderate. •

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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. •
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