Tendon Integrity and Functional Outcome After Arthroscopic Repair of High-Grade Partial-Thickness Supraspinatus Tears

Kamath, Ganesh MD; Galatz, Leesa M. MD; Keener, Jay D. MD; Teefey, Sharlene MD; Middleton, William MD; Yamaguchi, Ken MD

Journal of Bone & Joint Surgery - American Volume:
doi: 10.2106/JBJS.G.00118
Scientific Articles
Abstract

Background: Partial-thickness rotator cuff tears are a common cause of shoulder pain, yet the appropriate surgical treatment is controversial. In particular, very little information is available regarding rotator cuff integrity after operative repair. The purpose of this study was to evaluate the functional outcome and anatomic healing rate after arthroscopic repair of high-grade partial (>50%) thickness tears of the supraspinatus tendon.

Methods: Forty-one consecutive patients (forty-two shoulders) who had undergone arthroscopic conversion of a partial-thickness rotator cuff tear to a full-thickness tear and subsequent repair were evaluated with ultrasound for evidence of rotator cuff healing. Clinical outcomes were assessed with use of validated outcomes measures, and all patients were reexamined by an independent observer.

Results: The average patient age was fifty-three years. Thirty-seven (88%) of the forty-two shoulders had an intact rotator cuff repair seen on ultrasound at an average of eleven months postoperatively. The remaining five patients had a full-thickness defect in the tendon. The mean American Shoulder and Elbow Surgeons (ASES) score improved from 46.1 points preoperatively to 82.1 points at the time of follow-up. The overall rate of patient satisfaction was 93%. The average age of the patients with an intact rotator cuff was 51.8 years compared with 62.6 years for those with a persistent defect (p = 0.02).

Conclusions: Arthroscopic repair of high-grade partial-thickness rotator cuff tears results in a high rate of tendon healing. Patient age is an important factor in tendon healing.

Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Author Information

1Shoulder and Elbow Service, Department of Orthopaedic Surgery, Washington University, Campus Box 8233, 660 South Euclid Avenue, St. Louis, MO 63110. E-mail address for L.M. Galatz: galatzl@wustl.edu

2Mallinckrodt Institute of Radiology, 510 South Kingshighway Boulevard, St. Louis, MO 63110

Article Outline

Partial-thickness tears of the rotator cuff are a common source of shoulder pain, yet treatment strategies remain highly controversial. A percentage of partial-thickness rotator cuff tears will not heal with conservative treatment and require surgical management1-7. While there is debate regarding the threshold of tendon injury that requires repair, evidence suggests that some patients with a high-grade partial tear benefit from formal repair rather than débridement and/or acromioplasty alone1,8-12.

Tendon healing is a primary concern following surgical repair. Several studies have shown that larger, chronic rotator cuff tears with irreversible muscle atrophy and tendon degeneration have lower healing rates following surgery than smaller tears13-17. There have been reports of substantial rates of clinical failure of the treatment of smaller tears as well13,14,17-19. Increasing evidence suggests that patient age may be a prominent factor affecting healing13,20,21.

Partial-thickness tears of the rotator cuff probably represent an early stage in the evolution of rotator cuff disease. Studies of the results after débridement alone have revealed a risk of progression to full-thickness tears with little evidence of spontaneous healing8,9. While local tendon injury and degeneration are invariably present22,23, partial-thickness tears are not associated with the severe tendon degeneration and muscle atrophy that accompany larger, full-thickness tears. Consequently, operative repair of partial tears may represent an opportunity for improved healing rates in comparison with the rates after repair of established full-thickness tears. Several authors have reported good clinical success following repair of partial-thickness rotator cuff tears with either open or arthroscopic techniques7,12,24-26. However, to our knowledge, no studies have documented the healing rate following repair of partial-thickness rotator cuff tears.

The primary purpose of this study was to report the rate of healing of high-grade partial (>50%) thickness rotator cuff tears in a cohort of patients treated with arthroscopic conversion to a full-thickness tear followed by surgical repair. Other patient factors relevant to healing were examined for possible correlation with the postoperative tendon integrity and clinical outcome.

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Materials and Methods

Inclusion Criteria

Approval was obtained from our institutional review board prior to enrollment of patients in the study.

A query of operative records of all surgical procedures performed between 2003 and 2005 by two fellowship-trained shoulder and elbow surgeons at our institution was performed. All patients who had undergone an arthroscopic conversion of a partial-thickness rotator cuff tear of the supraspinatus tendon to a full-thickness tear followed by a repair were identified. Patients who had had a repair of a high-grade partial (>50%) thickness tear of the supraspinatus that did not extend into the posterior aspect of the rotator cuff were included in the study. The preoperative diagnosis of a partial-thickness tear of the rotator cuff was made with either ultrasound or magnetic resonance imaging. The diagnosis of a high-grade partial-thickness rotator cuff tear was confirmed arthroscopically, at the time of the repair, by visual assessment of the footprint. The tears were treated with tendon débridement to achieve a full-thickness tear followed by arthroscopic repair with suture anchors. Surgery was indicated after failure of nonoperative management consisting of rotator cuff strengthening exercises and nonsteroidal anti-inflammatory medication for at least three months. Patients who had had concomitant shoulder procedures (biceps tenotomy or tenodesis, superior labral repair, or distal clavicular resection) were included. Patients who had persistent shoulder pain following previous subacromial decompression and tendon débridement without rotator cuff repair were also included.

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Exclusion Criteria

Patients with a <50%-thickness tear treated with only débridement and subacromial decompression and those in whom the tear extended posteriorly into the infraspinatus tendon insertion were excluded. Patients in whom the partial-thickness tear was treated with débridement, or repair in situ without conversion to a full-thickness tear, were excluded as well. Patients with a previous rotator cuff repair and those with a partial-thickness tear repaired with a side-to-side tendon suture technique were also excluded.

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Patient Evaluation

All patients completed a standard medical questionnaire at the initial office presentation. Medical comorbidities, age, sex, and smoking history were documented. The integrity of the rotator cuff repair was determined with ultrasound examination at a minimum of six months after the surgery. All sonograms were made with use of an ATL HDI 5,000 Scanner (Advanced Technologies Laboratory, Bothell, Washington) and a variable high-frequency linear-array transducer (7.5 to 10 MHz) as previously described27. Dynamic and static imaging sequences of the rotator cuff were obtained in both the transverse and the longitudinal plane after initial examination of the biceps tendon in the transverse plane. An intact repair was defined as continuity of the repaired cuff to the greater tuberosity (Fig. 1). A recurrent tendon defect was diagnosed when a distinct hypoechoic or mixed hyperechoic and hypoechoic defect could be visualized in both the transverse and the longitudinal plane at the articular attachment on the greater tuberosity (Fig. 2). A full-thickness tear was diagnosed if there was a focal defect in the rotator cuff into which the deltoid muscle could be compressed manually to separate the torn tendon ends, or if the cuff had retracted to such an extent that the torn ends could be distinctly visualized. Ultrasound has been validated as an accurate method of assessing rotator cuff integrity in the postoperative setting at our institution28. All ultrasound studies were performed by one of two experienced musculoskeletal radiologists with fellowship training in the field and more than fifteen years' experience with the technique.

The postoperative clinical outcome was determined at a minimum of twenty-four months after the surgery. A standard history was recorded for each patient and a physical examination was performed by an independent observer (a senior-level resident or an independent research nurse trained in shoulder and elbow evaluation) according to the criteria outlined by the American Shoulder and Elbow Surgeons (ASES)29. All patients completed a standardized questionnaire with scales for evaluating both pain and function. Return-to-work status was documented for all patients. Preoperative pain levels according to visual analog scores and ASES scores29 were obtained by chart review.

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Surgical Procedure

All procedures were performed with the patient under general anesthesia, and an adjunctive interscalene block was used as well in ten patients. The patients were positioned in the upright beach-chair position. Diagnostic arthroscopy was performed to assess the rotator cuff and associated pathological conditions. Subacromial decompression was performed in all patients. Acromioplasty was limited to removal of osteophytic bone. If the undersurface of the acromion was free of osteophytes, a débridement of inflamed bursal tissue was performed, with minimal decortication of the acromial undersurface and with release of the coracoacromial ligament.

The rotator cuff was carefully examined from both the articular and the bursal side. All partial-thickness rotator cuff tears described in this study were isolated to the supraspinatus tendon. Frayed rotator cuff tissue was débrided, and the thickness of the tear was measured starting lateral to the edge of the articular surface of the humeral head. A tagging suture was placed at the sites of the articular-sided tears for identification of the location from the bursal side. Bursal-sided injuries were probed extensively for thinning of the tendon. The extent of the tear was evaluated by visual assessment of the footprint. If the tear was found to involve ≥50% of the thickness of the tendon (5 to 6 mm), then the tendon was split longitudinally to confirm the thickness of the tear. The tendon split was made in line with its longitudinal fibers to allow visualization of the entire tendon thickness. A minimum amount of the footprint was released to allow full access to the tear. High-grade articular-sided tears were evaluated from the bursal side after identification of the tagging suture and were completed sharply with a scalpel. The operative indication for repair of a partial-thickness tear was a tear width exceeding 50% of the tendon thickness (5 to 6 mm).

A limited débridement that included only the diseased portion of the tendon was performed in order to convert the tear to a full-thickness tear. The greater tuberosity was débrided of soft tissue to expose the cortical bone. Metal corkscrew anchors double-loaded with braided nonabsorbable number-2 FiberWire suture (Corkscrew Suture Anchor; Arthrex, Naples, Florida) were then placed into the greater tuberosity. Given the small size of the majority of the tears, most were repaired with a single anchor. The torn tendons were repaired to the tuberosity with a combination of simple and/or horizontal mattress suture constructs. Single and double-row repairs were utilized depending on the timing of the surgery (early or late in the inclusion period), surgeon preference, and individual patient factors. At the end of the procedure, a catheter was routinely placed within the subacromial space under direct visualization for the administration of anesthetic medication postoperatively.

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Rehabilitation

The patients were treated with a standard postoperative protocol that included sling immobilization with immediate elbow, wrist, and hand motion. A passive range of motion of the shoulder into flexion, scapular plane elevation, and external rotation was initiated immediately in the postoperative period. Active range-of-motion and pulley exercises began at six weeks following surgery. At six to eight weeks, graduated strengthening exercises of the rotator cuff, the deltoid, and the scapular stabilizers were begun. High-level recreational activities and/or manual labor were not allowed until four to six months after the operative procedure.

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Statistical Analysis

Comparisons of preoperative and postoperative outcomes were carried out with the paired t test. Analysis of covariance was used to compare the pain and function scores between the shoulders with a healed rotator cuff repair and those with a recurrent tear. The Fisher exact test was employed to analyze variables related to tendon integrity following surgery. An unpaired t test was used to compare the ages of the patients with a healed tendon with those of the patients with a recurrent tear. Distributional and model-specific assumptions were verified for all statistical tests performed.

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Source of Funding

There was no external funding source for this study.

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Results

Clinical Examination

Forty-eight shoulders in forty-seven patients were eligible for participation in the study. Forty-one patients with forty-two involved shoulders returned for follow-up, and they were the study population. Five patients elected not to participate in the study because of scheduling constraints, and one patient was lost to follow-up. The final assessment of the clinical outcomes was performed at a minimum of twenty-four months after the surgery.

Postoperative ASES questionnaires and ultrasound examinations were completed for all patients. Two patients had a postoperative ultrasound study and an initial excellent outcome (ASES scores of 82 and 95 points) at six months, but one was lost to follow-up and another died secondary to metastatic pancreatic cancer less than twenty-four months postoperatively. Preoperative ASES and pain scores were available for all but three patients (see Appendix). Forty shoulders had a chronic tear (present for more than three months without a history of trauma), and two had an acute-on-chronic injury (previous shoulder pain aggravated by a recent injury). There were twenty-one men and twenty women. The average age was fifty-three years (range, thirty-four to seventy-two years). The average duration of clinical follow-up was thirty-nine months (range, twenty-five to fifty months). Of the forty-two partial-thickness rotator cuff tears, twenty-eight involved the right shoulder and fourteen involved the left shoulder. There were thirty-three articular-sided and nine bursal-sided partial-thickness rotator cuff tears.

Thirty-seven shoulders had a repair with a horizontal mattress construct and a single suture anchor, and five had a double-row repair with one or more medially placed anchors as well as a separate laterally placed suture anchor for recreation of the tendon footprint. Seventeen shoulders had a concomitant procedure in addition to the rotator cuff repair. Two underwent repair of a type-II SLAP (superior labrum anterior and posterior) tear, two underwent a biceps tenotomy, and three had a biceps tenodesis. Two shoulders had an arthroscopic repair of a partial-thickness superior subscapularis tendon tear. Five shoulders underwent arthroscopic distal clavicular resection to treat a painful acromioclavicular joint. One shoulder had a focal full-thickness cartilage defect on the glenoid treated with microfracture, and one underwent removal of articular loose bodies associated with synovial chondromatosis. A pre-acromion-type os acromiale was resected in one patient.

The average visual analog pain score improved from 6.65 points (range, 2 to 10 points) preoperatively to 2.7 points (range, 1 to 9 points) postoperatively. The average ASES score improved from 46.1 points (range, 10 to 87 points) preoperatively to 82.1 points (range, 23 to 100 points) postoperatively. The improvement in both the visual analog pain score (p < 0.0001) and the ASES score (p < 0.0001) was significant (Table I). The visual analog pain score was ≤3 points for twenty-nine (73%) of the shoulders at the time of final follow-up. Twenty-seven shoulders (68%) had a postoperative ASES score of >80 points, and all but one of the patients demonstrated an improvement in the ASES score. The rate of patient satisfaction with the outcome of surgery was 93% (thirty-seven of forty shoulders), and 93% were able to return to their previous occupation.

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Ultrasound Examination

Ultrasound examination was performed on all shoulders at a minimum of six months after the surgery, and it documented healing of the rotator cuff repair in thirty-seven (88%) of the forty-two shoulders. A full-thickness tendon defect was seen in the remaining five shoulders. Two of the five tears were smaller than the original partial-thickness tear, two were approximately the same size, and one was larger. Of the five shoulders with a rotator cuff defect at the time of follow-up, two had originally had a bursal-sided tear and three had had an articular-sided tear. A double-row cuff repair had been performed in two shoulders with a recurrent defect, and the remaining three shoulders had had a single-row repair.

The average postoperative visual analog pain and ASES scores were 2.9 and 82.9 points, respectively, for the shoulders with a healed repair and 3.2 and 76.7 points for those with a recurrent tear. With the numbers in this study, we could not identify a difference in the improvement in the visual analog pain score between the shoulders with an intact rotator cuff (3.8 points) and those with a recurrent tear (3.8 points) (Table II). Likewise, there was no significant difference in the improvement in the ASES score between the shoulders with an intact rotator cuff (36.2 points) and those with a recurrent tear (32.2 points).

A post hoc calculation of the statistical power of the study to detect a difference between the two groups (healed and recurrent tears) was performed (alpha = 0.05, power = 0.80). Given the size of the group that had a recurrent tear as compared with that of the cohort with a healed tendon, our sample size was sufficient to identify a difference of 25 points in the ASES scores, 3.5 points in the visual analog scores, and 18 points in the ASES function scores.

Again, with the small number of study subjects, we were not able to distinguish between the two groups on the basis of tear location (articular compared with bursal-sided), repair type (single compared with double-row), or smoking history. However, the average age of the patients with a recurrent defect (62.8 years) was older than that of the patients with a healed repair (51.8 years) (p = 0.02).

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Complications

There were no postoperative infections or implant-related complications. A frozen shoulder developed in two patients postoperatively. In one of them, it was treated effectively with a single cortisone injection into the glenohumeral joint, and the patient ultimately had an excellent result with an ASES score of 100 points. In the other patient, the postoperative frozen shoulder was treated with arthroscopic capsular release and manipulation. This patient reported persistent shoulder pain (visual analog pain score, 9 points) and limited function. The final ASES score was 55.2 points. One patient later underwent an arthroscopic distal clavicular resection to address pain localized to the acromioclavicular joint, and the final ASES score was 91.7 points. One patient underwent arthroscopic coracoidplasty because of persistent anterior shoulder pain (final ASES score, 28.3 points), and another patient underwent arthroscopic scapulothoracic bursectomy because of persistent scapulothoracic bursitis (final ASES score, 90.0 points). All of these five patients with a postoperative complication had documented healing of the rotator cuff on the postoperative ultrasound examination.

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Discussion

These results confirm that arthroscopic conversion of a partial-thickness rotator cuff tear to a full-thickness tear followed by repair is a highly effective treatment option. Results were analyzed with use of validated outcomes measures and with ultrasound to assess tendon healing. Eighty-eight percent (thirty-seven) of forty-two operative repairs were healed at six months after the surgery. The relatively high rate of healing is probably related to the small tear sizes and the young age of our patients, which is typical of our patient population with this clinical problem. Age was significantly related to successful repair. Tendon degeneration in the setting of a partial-thickness rotator cuff tear is usually focal, and the environment for healing following aggressive débridement and repair may be more favorable than that for larger, full-thickness cuff tears16,30. These results are consistent with those following full-thickness repair and highlight the importance of patient age as a factor influencing healing13,31.

Treatment of symptomatic partial-thickness rotator cuff tears is controversial. Surgical strategies range from simple débridement and acromioplasty alone to aggressive surgical débridement and repair. Recent studies indicate that partial tears have the potential to progress to full-thickness tears and that débridement does not alter the course8,32. Kartus et al. recently studied the cases of twenty-six patients with a partial-thickness rotator cuff tear treated with tear débridement and acromioplasty8. At a minimum of five years postoperatively, ultrasound examination demonstrated that a full-thickness tear had developed in nine (35%) of the twenty-six patients. The authors concluded that acromioplasty and débridement do not prevent further degeneration of the rotator cuff. Weber noted that patients in whom a partial-thickness rotator cuff tear had been treated with a mini-open repair had better outcomes than did a similar group treated with débridement and acromioplasty alone9. Alarmingly, three of their thirty-two patients treated with acromioplasty alone had a rupture of the remaining rotator cuff. None of the partial tears treated with acromioplasty alone were seen to be healed with second-look arthroscopy. In a prospective arthrography study, Yamanaka and Matsumoto noted that only four of forty partial-thickness rotator cuff tears were not visualized on follow-up arthrography after nonoperative treatment33. Half of the tears appeared to be larger than the original tear, and a quarter had progressed to a full-thickness rotator cuff defect. Taken together, these studies demonstrate that partial-thickness rotator cuff tears have a low potential for spontaneous healing and that débridement and acromioplasty do not alter the natural progression of rotator cuff disease. In patients with a high-grade partial tear (involving >50% of the tendon), conversion to a full-thickness tear followed by repair may alter the degenerative process by removing the diseased portion of the tendon and allow healing of the remaining healthy tendon to bone.

It should be emphasized that, although the literature suggests that a relatively high percentage of partial-thickness tears treated with débridement and acromioplasty develop into full-thickness tears, only 12% (five) of the forty-two shoulders in our study had a persistent defect equivalent to a complete rotator cuff tear after surgical treatment. This finding is in the context of no patient having had a full-thickness defect prior to surgery. While this percentage of persistent defects may compare favorably with the percentage following débridement and acromioplasty alone, or with the percentage in our previous series of patients with a chronic full-thickness tear30, it remains to be seen whether other surgical strategies such as in situ or transtendon repair without complete conversion to a full-thickness tear would result in a better healing rate.

The short-term clinical results in our series are comparable with those in published reports on repair of partial-thickness tears12,24-26. The average visual analog pain score decreased from 6.5 to 2.7 points, and the average ASES score improved from 46.1 to 82.1 points. Interestingly, the clinical outcomes for the shoulders with a healed repair and those with a recurrent tear were similar. We acknowledge, however, that this is a short-term study, with an average duration of follow-up of thirty-nine months. Longer-term studies have shown a correlation between cuff integrity and shoulder strength and function13,16,31,34. Furthermore, the clinical outcome may have been influenced by concomitant procedures performed at the time of the repair.

These findings may support surgical treatment of partial-thickness rotator cuff tears. Partial-thickness rotator cuff tears usually occur in younger patients and are small. Since débridement alone neither prevents progression nor relieves pain reliably, we reason that arthroscopic conversion to a full-thickness tear followed by repair is a viable treatment for symptomatic high-grade partial-thickness rotator cuff tears.

Strengths of our study include the low rate of attrition of eligible patients and the use of a validated imaging modality with independent observers for assessing rotator cuff integrity postoperatively29. Ultrasound has the advantage of being a dynamic study and has been documented to have high sensitivity and specificity in the postoperative assessment of the shoulder28.

This study had several limitations. The clinical outcome was assessed at a minimum of twenty-four months. However, the primary objective of the study was to assess healing of the surgical repair. The time point for examination of cuff integrity was six months, chosen on the basis of in vivo animal studies of rotator cuff repair. In both goat and sheep models, load-to-failure testing at twelve weeks showed that the point of failure had shifted proximally from the repair site to the musculotendinous junction, implying healing at the bone-tendon junction35-37. Six months following surgery should have been adequate time for tendon healing and rehabilitation of the shoulder in our patients. We acknowledge that additional, longitudinal studies and evaluations of greater numbers of patients are necessary to fully understand the importance of rotator cuff integrity with regard to functional outcome at the time of long-term follow-up.

Several surgical variables were not controlled for because of the retrospective nature of the study. These include the type of repair construct and concomitant surgical procedures. Arthroscopic conversion to a full-thickness tear followed by repair is our preferred surgical technique because it allows increased access for tear débridement and removal of degenerative tissue, but we are not aware of any studies in which this approach was directly compared with either transtendon or in situ techniques. The majority of repairs in our study consisted of simple and mattress stitches and use of one or two suture anchors; however, five shoulders were repaired with a double-row technique. The surgical technique varied according to surgeon preference, tear size, date of surgery, and patient-specific factors. We acknowledge that this introduces several confounding variables into a comparison of repair constructs and limits comparison of repair types. While double-row repairs may be stronger biomechanically38,39 and better recreate the native footprint of the supraspinatus tendon40,41, the importance of this construct is controversial as several studies have not demonstrated better healing rates with double-row repair42,43. It should be noted that two of the five double-row repairs performed in this study did not heal. It is possible that other factors related to the biology of the tear, such as patient age, may be more important than the mechanical strength of the repair of small tears. Seventeen (40%) of the forty-two shoulders had additional procedures at the time of the index surgery, and these additional procedures may have influenced the functional outcome scores. The measurement of subjective postoperative outcomes scores, such as visual analog pain and ASES function scores, may be confounded by the inclusion of these patients. Although it is possible that the presence and treatment of associated pathological conditions may have influenced the clinical outcomes, they are unlikely to have affected the primary ultrasonographic measure of tendon healing.

Arthroscopic conversion of a high-grade partial-thickness rotator cuff tear to a full-thickness tear followed by repair produces a high rate of tendon healing in patients for whom conservative treatment has failed. The clinical results in this series were good and comparable with those in other series of patients treated for partial-thickness rotator cuff tears. The rate of tendon healing compares favorably with rates previously reported for full-thickness tears. Increasing patient age adversely affects tendon healing. Our clinical results in patients with a high-grade partial-thickness tear were better than the reported results of débridement and acromioplasty alone, and this approach provided a substantially increased likelihood of rotator cuff healing.

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Appendix Cited Here...

A table presenting details on all study subjects is available with the electronic versions of this article, on our web site at jbjs.org (go to the article citation and click on “Supplementary Material”) and on our quarterly CD/DVD (call our subscription department, at 781-449-9780, to order the CD or DVD).

Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits of less than $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Arthrex). Also, a commercial entity (Arthrex) paid or directed in any one year, or agreed to pay or direct, benefits in excess of $10,000 to a research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which one or more of the authors, or a member of his or her immediate family, is affiliated or associated.

A commentary is available with the electronic versions of this article, on our web site (www.jbjs.org) and on our quarterly CD-ROM/DVD (call our subscription department, at 781-449-9780, to order the CD-ROM or DVD).

Investigation performed at the Shoulder and Elbow Service, Washington University Orthopaedics, Barnes-Jewish Hospital, St. Louis, Missouri

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