Superior Capsule Reconstruction: A Glimpse into the Future?

Introduction

The treatment of massive and irreparable rotator cuff tears continues to be a challenge for orthopedic surgeons. In the elderly population, reverse shoulder arthroplasty is a salvage procedure that has been shown to reliably provide pain relief and improve shoulder elevation [2, 5, 17, 21, 22]. However, the appropriate management of this condition in younger, more active patients with higher functional demands remains elusive [20]. The superior capsule reconstruction (SCR) was recently developed as a treatment option to restore shoulder function and reduce pain for patients with massive rotator cuff tears and has been hailed by some as a solution to this challenging condition [15]. In this technique, a graft, typically fascia lata autograft or dermal allograft, is introduced and secured to span from the superior aspect of the glenoid to the greater tuberosity. The graft resists superior translation of the humeral head, thus recreating superior shoulder stability without the necessity of rotator cuff tendon repair.

Early results of SCR procedures have been mixed. Some studies have shown marked improved shoulder range of motion, strength, and functional outcomes scores and a reduced incidence of rotator cuff arthropathy [11–13]. Other studies, however, suggest that the SCR grafts fail at a high rate [4, 23].

The controversies that continue to swirl over the ultimate efficacy of SCR center around two major discussion points: graft selection and graft thickness. Most ardent proponents of SCR endorse the use of fascia lata autograft for its thickness and stiffness [9, 14]. This approach requires patients to undergo a second, graft harvesting procedure, increasing the morbidity of the SCR procedure as a whole. Many others have preferred the use of dermal allograft [1, 6]. Dermal allografts tend to be thinner than fascia lata autografts and are associated with increased rates of graft lengthening and failure [4, 16, 18]. These findings have prompted biomechanical research investigating graft thickness as the key factor in obtaining a successful superior capsule reconstruction.

While these controversies continue to spark debate and inspire further research, it is important to recognize the growing need for longer term outcomes to assess efficacy or materials and techniques. The recent study by Mihata et al., which presented 5-year clinical and radiographic outcomes for patients undergoing SCR using fascia lata autograft, represents an important step toward better understanding the role of SCR in massive rotator cuff tears. This review will strive to highlight in what way this study should shape future thinking about SCR as a treatment option for massive RCTs. It will also attempt to position this article within the ongoing debates surrounding optimal graft selection and thickness. Finally, we will discuss the future direction of research surrounding SCR in the field of orthopedics.

The Article

“Five-year follow-up of arthroscopic superior capsule reconstruction for irreparable rotator cuff tears.”

Mihata T, Lee TQ, Hasegawa A, Fukunishi K, Kawakami T, Fujisawa Y, Ohue M, Neo M. J Bone Joint Surg Am. 2019;101:1921–1930.

In this study, the authors present the 5-year clinical and radiographic outcomes of 30 patients who underwent arthroscopic superior capsule reconstruction using fascia lata autograft for massive, irreparable rotator cuff tears. They selected a reasonably young group of patients (mean age: 68), with higher than usual physical demands: 12/30 were physical laborers (40%) and 8/30 (27%) were still actively participating in sports. Irreparable cuff tears were defined as those for which the original tendon could not be stretched to cover the original tendon footprint intraoperatively, even after releases were performed. Specific endpoints for analysis included healing and thickness of the SCR graft, subjective pain levels, shoulder range of motion, validated outcomes measures such as the American Shoulder and Elbow Surgeons (ASES) and Japanese Orthopaedic Association scores, and radiographic measurements of acromiohumeral distance.

All grafts were prepared by folding fascia lata either two or three times in order to achieve the minimum graft thickness of 4 mm. Capsular release was performed with an effort made to retain the biceps anchor intact to the superior glenoid rim. The graft was secured to the superior aspect of the glenoid utilizing two suture anchors, while the lateral aspect of the graft was fastened to the rotator cuff footprint on the greater tuberosity using either a transosseous equivalent or compression double-row technique. Side-to-side sutures were placed between the graft and the infraspinatus or teres minor tendon to further solidify the repair. Post-operative protocols were consistent between all patients and consisted of 4 weeks of shoulder immobilization in 30–45° of abduction using a sling, followed by a graduated increase in passive and active range of motion and cuff strengthening exercises.

The authors demonstrate excellent clinical and radiographic outcomes for their patients. Rates of graft healing were 90%, as determined by assessment of T2-weighted magnetic resonance imaging (MRI), with no difference noted in patient age or pre-operative Goutallier or Hamada grade between those with healed and failed grafts. The ASES score improved at both 1 year (83.0) and 5 years (92.3) compared with pre-operative baseline (29.0) as did the JOA score: 85.9 at 1 year and 91.4 at 5 years compared with 51.5 pre-operatively. The authors also noted significantly reduced VAS at 1 and 5 years post-operatively and significantly increased range of motion overall. Radiographic outcomes demonstrate a significantly increased acromiohumeral distance at both 1 year (increase in 5.7 mm) and at 5 years (increase in 4.7 mm) as compared with pre-operative evaluation. For all patients with a healed graft, there was no progression of cuff tear arthropathy. The three patients with failed grafts all developed severe glenohumeral arthritis and associated rotator cuff arthropathy.

Commentary

The purpose of this review is to provide a critical analysis of the recent article published by Mihata et al. presenting 5-year clinical and radiographic outcomes of SCR used for treatment of massive and irreparable rotator cuff tears. It also seeks to frame the study within the context of a growing body of literature surrounding management of this challenging orthopedic condition.

When it was first proposed in the early 2010s, the SCR procedure carried a great deal of promise as a means for combating irreparable rotator cuff pathology in young, active patients who were poor candidates for shoulder arthroplasty. For the better part of a decade, surgeons have been honing surgical techniques and experimenting with different types of augmentation grafts. Current orthopedic literature is divided into two major schools of thought surrounding graft selection for SCR: fascia lata autograft versus dermal allograft. The best results to date have been demonstrated by a select group of surgeons utilizing fascia lata autograft. In a study by Mihata et al. from 2013, 24 patients were treated with SCR for irreparable rotator cuff tears with statistically significant improvements in active elevation (84 to 148), external rotation (26 to 40), and acromiohumeral distance (4.6 pre-operatively to 8.7 post-operatively) [13]. Another study of 31 patients treated with SCR using fascia lata autograft also demonstrated significant improvement in range of motion, shoulder constant score, pain levels, and acromiohumeral distance [7]. This group credits the thickness and stiffness of the fascia lata autograft with providing a more stable artificial superior capsule that prevents superior migration of the humeral head thus restoring normal joint forces.

On the other hand, particularly in the USA, many surgeons have preferred to use dermal allograft in their SCR procedures. However, these studies have yielded mixed results overall. Some studies, as in the case of Burkhart et al., demonstrated statistically significant improvements in active range of motion, functional outcomes, and overall pain levels in a series of 10 patients treated with SCR using 3-mm-thick dermal allograft [3]. While Denard et al. demonstrated improvements in range of motion as well as functional outcomes and pain, their results suggested that fewer than 50% of patients demonstrated signs of complete healing after 18 months with elevated rates of graft failure [4]. Similarly, in a separate study, as high as 65% graft failure rate was noted with dermal allograft [6].

These allografts are consistently thinner than fascia lata autograft leading some to posit graft thickness, rather than the graft material, is key to a successful outcome. This has sparked biomechanical research into differences in shoulder stability due to graft thickness. Scheiderer et al., in a biomechanical study of 8 cadaver specimens, determined that 6-mm dermal allograft better restored normal glenohumeral alignment and joint forces when compared with 3-mm dermal allograft [19]. Moreover, Mihata et al. demonstrated improved shoulder stability and joint forces with use of 8-mm fascia lata autograft as compared with 4-mm graft, further supporting the idea that graft thickness is paramount [14]. A recent study comparing glenohumeral stability with 3-mm dermal allograft versus fascia lata autograft exhibited increased efficacy with the fascia lata autograft [8]. Further studies comparing similar graft thickness dermal allograft and fascia lata autograft are needed to compare the intrinsic strength and efficacy of the two materials.

As the first study to report 5-year outcomes for patients undergoing SCR, Mihata et al. should be applauded for taking an important step toward our overall understanding of the natural history of SCR operations. Their results compare favorably with prior clinical outcomes studies and demonstrate excellent rates of graft healing (90%), improved range of motion and functional outcomes scores, reduced pain, and prevention of rotator cuff arthropathy for their cohort of patients. Their study makes a strong case for SCR as a viable option to treat irreparable rotator cuff tears in young, active patients.

However, as they alluded to within the “Discussion” section of their study, these results must be interpreted cautiously. To begin, the study is small with only 30 total patients with a minimum of 5 years of clinical and radiographic follow-up. The rate of patients lost to follow-up was also considerable (19%), which may have impacted results. A degree of selection bias is unavoidable in a case series such as theirs, where there is neither randomization nor blinding of patient nor practitioner. Additionally, while the authors describe the use of T2-weighted MRI for the assessment of graft healing, they fail to define specific criteria for a healed graft, or who reviewed the MRI studies, raising questions about the reliability of their results. With the exception of the fixation technique, where the authors accepted either the use of a double-row or transosseous equivalent fixation, the authors should be commended for their efforts to limit confounders by standardizing surgical approaches and post-operative protocols. However, this narrow focus limits the external validity of the study. It becomes more challenging to predict to what extent the results of the study are reproducible in other settings.

In the context of orthopedic surgery as a whole, the SCR procedure is still in its nascent phases. Further studies, including prospective cohort studies and randomized controlled trials, are warranted to better appreciate the efficacy of the procedure, especially those comparing similar thickness dermal allograft to fascia lata autograft. Even longer term research into the clinical outcomes of patients with dermal allograft utilized for SCR procedures would serve as a useful comparison for this study. Much of our contemporary understanding of the SCR procedure and its outcomes comes from the same, small group of surgeons. This is not unusual for a new technique or operation gaining traction and popularity amongst surgeons worldwide. As the wealth of outcomes data continues to grow and become more heterogeneous, our understanding of the ultimate reach of this procedure will improve. There can be no question that the SCR procedure demonstrates great promise as a solution to the difficult problem of how to treat young, active patients with irreparable rotator cuff tears. However, until we obtain further answers to important questions surrounding graft selection, and boast a more robust reservoir of long-term outcomes from a diverse group of publications, its true potential will remain hidden.

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