Stress Fractures After rTSA. Not Every Onlay is Created Equal.

Ian Byram, MD

Read complete study: Increased scapular spine fractures after reverse shoulder arthroplasty with a humeral onlay short stem: an analysis of 485 consecutive cases

Since its FDA clearance in 2003, reverse shoulder arthroplasty (RSA) has become increasingly utilized for the treatment of arthritis, fractures, and rotator cuff failures in the United States. Initial reports demonstrated a high rate of complications, including instability, impingement, scapular notching, and subsequent implant failure.Many implant designs have been successfully modified to minimize these problems. While scapular notching seen with the initial Grammont style prosthesis has decreased with modern lateralized implant designs, scapular spine fractures have become more prevalent.

The authors of this study analyzed a series of RSA cases utilizing a short stem, 145° neck-shaft inclination prosthesis hoping to shed light on implant features that may lead to scapular spine fractures. In a retrospective review of 485 consecutive arthroplasties, they reported 21 (4.3%) scapular spine fractures that were diagnosed at a mean of 8.6 months after surgery. Comparing those patients with matched controls, patients with fractures demonstrated significantly worse Constant scores and forward flexion. They concluded that utilization of a lateralized “onlay” convertible humeral design creates increased stress on the deltoid and acromion, resulting in an undesirable rate of scapular spine and acromial fractures.

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Scapular Fractures After RSA – The Bane of Our Existence

Stephanie Muh, MD

Read complete study: Scapular fracture in reverse shoulder arthroplasty (Grammont Style): prevalence, functional, and radiographic results with minimum 5-year follow up

The development of postoperative scapular spine or acromial base fractures remains a difficult problem to treat. With a reported incidence of 1-10% in the literature, there has been no consensus on the best treatment, and most authors report poor post-fracture functional outcomes.1-3 Both operative and nonoperative management of these fractures have been advocated with variable outcomes.2,3

This retrospective study presents data from a large cohort of patients with a single prosthetic design (Grammont style with medialized center of rotation and medialized humerus with inlay prosthesis). The authors found an overall prevalence of 1.3% scapular fractures in 1,953 implants. This seems to correlate with other literature where the incidence ranged from 1-10%.1-4 When evaluating the functional results with a minimum of five years follow-up, 19 fractures were identified with an overall improved range of motion and Constant score. It is important to note, however, the patients with fractures did not improve as greatly as those without fractures. While the postoperative Constant score improved from 25.6 to 47 postoperatively, the authors note the average postoperative Constant score in a non-fracture group is 70. They did not directly compare the fracture group range of motion to non-fracture group which I think would have added valuable information. It would have been interesting if the authors presented initial improvement postoperatively and compared this to post-fracture outcomes and commented if there was function.

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To Repair, or Not to Repair, That is the Question…

Kaveh Sajadi, MD

Read complete study: The effect of subscapularis repair on dislocation rates in reverse shoulder arthroplasty: a meta-analysis and systematic review

Whether ‘tis nobler in the mind to bear the slings and arrows of our colleagues…

The role of the subscapularis in reverse total shoulder arthroplasty (rTSA) continues to be debated. Reverse TSA is most commonly performed via a deltopectoral approach, which often requires takedown of an intact, though possibly degenerated or atrophic, subscapularis tendon. Surgeons debate the importance of its repair at the conclusion of the surgery. This debate centers on the importance and role of the subscapularis in stability of the prosthesis, range of motion (both internal and external rotation), and outcomes. Those in favor of repair cite studies indicating lower dislocation rates with repair and better internal rotation; those opposed express concern about it potentially limiting external rotation and possibly opposing the deltoid in elevating the arm.1 This meta-analysis and systematic review sought to compare the dislocation rates and outcomes in rTSA with and without subscapularis tendon repair using the highest level of data available.

This meta-analysis and systematic review sought to compare the dislocation rates and outcomes in rTSA with and without subscapularis tendon repair using the highest level of data available.

It is important to clarify some descriptions used in the study. Since the introduction of the original Grammont style reverse prosthesis in the late 1980s and early 1990s, many different design modifications have been introduced.2 The primary differentiating characteristic between implant designs is the location of the center of rotation (COR) of the new glenohumeral articulation. By their very nature, all reverse designs medialize the COR compared with the native shoulder. However, systems with the COR at the glenoid face, as the original Grammont design, are considered medialized and those with the COR lateral to the glenoid are referred to in this paper as lateralized designs. Furthermore, the implant can have a medialized humerus (Grammont) or a lateralized humerus. Routman HD, et al, proposed a classification to standardize the nomenclature, dividing implants into the medial glenoid/medial humerus (Grammont), lateral glenoid/medial humerus, and medial glenoid/lateral humerus.2,3 Some of the implants in this study, classified as lateralized glenoids by the authors, are classified as medial glenoid/lateral humerus by Routman.

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The Effect of Lateralization on the Rotator Cuff Following Reverse Shoulder Arthroplasty

Stephanie Muh, MD

Read complete study: Clinical Outcomes after Reverse Shoulder Arthroplasty with and without subscapularis repair: The Importance of considering glenosphere lateralization

There continues to be significant debate on whether subscapularis repair is necessary during reverse total shoulder arthroplasty. Historically subscapularis repair was felt to be necessary to provide anterior soft tissue stability and help prevent post-operative dislocation. There have been multiple articles written on both the advantages and disadvantages of subscapularis repair. It should be noted that most previous articles that strongly advocated subscapularis repair included the traditional Grammont-style prosthesis with a medialized glenosphere and valgus medialized humeral stem (155 degrees).

This article retrospectively reviews patients who underwent reverse total shoulder arthroplasty (RTSA). They first stratified the subscapularis repair group versus no repair. The authors then looked at the effects of glenosphere lateralization (0mm lateralization vs +3 or +6mm) in both groups to determine if this played a significant role. The humeral stem used in the study has a neck shaft angle of 147 degrees but a humeral stem with no lateralization. ASES score from baseline was the primary outcome measured with a minimum of two-year follow-up.

The study demonstrated patients with no subscapularis repair and lateralization had the most overall improvement in ASES scores. This supports the design rationale of the Equinoxe® reverse shoulder system.

Overall, the authors found no difference in ASES scores when comparing subscapularis repair versus no repair. The authors also reported that subscapularis management and lateralized glenosphere individually did not have significant effect on ASES scores. However, analysis did find that patients with subscapularis repair with a lateralized glenosphere did worse compared to subscapularis repair with medialized glenosphere and no repair with lateralized glenosphere.

This article demonstrates the impact of the combined effect of subscapularis management with glenosphere lateralization on clinical outcomes. The study demonstrated patients with no subscapularis repair and lateralization had the most overall improvement in ASES scores. This supports the design rationale of the Equinoxe® reverse shoulder system. Continue reading

Revision with a Platform System

Alberto Rivera, MD

Read complete studies:

Conversion to reverse shoulder arthroplasty: humeral stem retention versus revision

Platform shoulder arthroplasty: a systematic review

The number of shoulder arthroplasty procedures is rapidly increasing. Therefore, shoulder revision is becoming a commonly performed procedure. Historically revising a hemiarthroplasty or total shoulder replacement ended up in a hemiarthoplasty, resection arthroplasty, arthrodesis or more recently reverse arthroplasty. This type of revision usually required stem removal, which could potentially lead to humeral fracture with or without the need of an osteotomy, increasing surgical time, bleeding and neural damage.  Also, late complications, such as osteotomy nonunion and malunion could develop. Another important factor to take into consideration is the added cost of using additional implants such as a new stem, cement, cables or allograft in the setting of humeral stem revision. Modular implants using a platform system allows for a faster revision with fewer complications and potentially less cost.

“Recent publication by Williams and Colleagues (1) reported on 17 patients who underwent modular conversion and nine who had revision of humeral stem. Pain, stability and ASES scores improved significantly.”

I believe the use of modular platform in primary shoulder arthroplasty either hemi or total should be the standard of care.

In my experience, revising TSA to RSA has evolved to a more straightforward procedure with the use of modular components of the platform shoulder type. I believe the use of modular platform in primary shoulder arthroplasty either hemi or total should be the standard of care.

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Can Sufficient Internal Rotation Be Achieved with Bilateral rTSA?

Thomas Wright, MD

Read complete study: Risk of insufficient internal rotation after bilateral reverse shoulder arthroplasty: clinical and patient reported outcome in 57 patients.

This study focused on the effects and risks of bilateral reverse shoulder arthroplasty (rTSA) on internal rotation (IR) in 57 patients. Data was recorded up to two years after the second surgery. The study found that only 15 percent of patients had insufficient IR in both shoulders after 12 months and 5 percent after 24 months. Patients who had insufficient baseline IR in their second shoulder and insufficient IR 12 month post op after their first shoulder had a 100 percent risk of having insufficient IR in both shoulders. The conclusion of this article is a recommendation to use staged bilateral rTSA over the use of a hemiathroplasty. The authors found that the majority of patients would undergo the surgery again, as it does provide benefits, like reduction in pain, regardless of the issues with IR.

Literature Review:

The authors of this study focused on the risks of staged bilateral rTSA on internal rotation. I agree with their concern, as bilateral decreased IR could result in difficulties with toileting. In my practice, I stage my bilateral cases; however the timing is up to the patient. I will proceed with the second surgery no sooner than 12 weeks, but I do not recommend waiting as long as a year. In 2014, we published an article on bilateral rTSA1 in which we found all patients eventually had enough IR to allow toileting with at least one shoulder. I agree with the authors and do not recommend using a hemiarthroplasty in the second shoulder, based on the positive results that we had with rTSA.

Although the article showed a 100 percent failure rate in achieving sufficient IR in the second shoulder when it comes to patients who have both insufficient baseline IR and insufficient IR 12 months post op in their first shoulder, we have not noted that to be a problem.

One example is a 79 year old male with symptomatic cuff tear arthropathy on the right and a failed total shoulder arthroplasty (TSA) on the left due to rotator cuff insufficiency.Because of the predictable nature of performing an rTSA as a primary, the right side was addressed first. At three months post-op he had IR to L5.

Figure_1

79 year old male, cuff tear arthropathy on the right side, 3 months post op

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