Reverse shoulder arthroplasty for massive rotator cuff tear: risk factors for poor functional improvement.

BACKGROUND: Some patients unexpectedly have poor functional improvement after reverse shoulder arthroplasty (RSA) for massive rotator cuff tear without glenohumeral arthritis. Our aim was to identify risk factors for this outcome. We also assessed the value of RSA for cases with poor functional improvement vs. METHODS: The study was a retrospective case-control analysis for primary RSA performed for massive rotator cuff tear without glenohumeral arthritis with minimum 2-year follow-up. Cases were defined as Simple Shoulder Test (SST) score improvement of ≤1, whereas controls improved SST score ≥2. Risk factors were chosen on the basis of previous association with poor outcomes after shoulder arthroplasty. Latissimus dorsi tendon transfer results were analyzed as a subgroup. Value was defined as improvement in American Shoulder and Elbow Surgeons (ASES) score per $10,000 hospital cost. RESULTS: In a multivariate binomial logistic regression analysis, neurologic dysfunction (P = .006), age <60 years (P = .02), and high preoperative SST score (P = .03) were independently associated with poor functional improvement. Latissimus dorsi tendon transfer patients significantly improved in active external rotation (-0.3° to 38.7°; P < .01). The value of RSA (ΔASES/$10,000 cost) for cases was 0.8 compared with 17.5 for controls (P < .0001). CONCLUSIONS: Young age, high preoperative function, and neurologic dysfunction were associated with poor functional improvement. Surgeons should consider these associations in counseling and selection of patients. Concurrent latissimus dorsi transfer was successful in restoring active external rotation in a subgroup of patients. The critical economic importance of improved patient selection is emphasized by the very low value of the procedure in the case group.

Outcome and value of reverse shoulder arthroplasty for treatment of glenohumeral osteoarthritis: a matched cohort.

BACKGROUND: Total shoulder arthroplasty (TSA) is commonly used to treat glenohumeral osteoarthritis (GHOA) with an intact rotator cuff. Recently, reverse shoulder arthroplasty (RSA) has been used for GHOA patients who are elderly or have eccentric glenoid wear. We evaluated patients with GHOA scheduled to have TSA but who were changed to RSA because of intraoperative difficulties with the glenoid component or instability and compared them with a cohort that underwent TSA to determine if the groups had similar outcomes. METHODS: We identified 24 consecutive GHOA patients who underwent RSA and matched them to 96 patients who underwent TSA. Glenoid wear and rotator cuff musculature were assessed with preoperative computed tomography scans. Direct hospital costs of the procedure were collected. RESULTS: Postoperative American Shoulder and Elbow Surgeons score, Simple Shoulder Test score, and range of motion were similar between the 2 groups. Five TSA patients had radiographic glenoid loosening, whereas no RSA patients did. Neither group required a revision. One RSA patient required surgery for treatment of a periprosthetic fracture. RSA was $7274 more costly than TSA, related mainly to implant cost. CONCLUSIONS: Patients with GHOA who were converted intraoperatively to RSA because of improper seating of the glenoid trial or persistent posterior subluxation had outcomes comparable to those of a similar group of patients in whom TSA was performed. At midterm follow-up, TSA is associated with lower cost than RSA. The higher rate of radiographic loosening in the TSA group warrants longer follow-up to assess revision costs. In cases in which a TSA cannot be performed with confidence, RSA is a reasonable alternative.

Glenosphere dissociation after reverse shoulder arthroplasty.

BACKGROUND: Reverse shoulder arthroplasty (RSA) is gaining popularity for the treatment of debilitating shoulder disorders. Despite marked improvements in patient satisfaction and function, the RSA complication rate is high. Glenosphere dissociation has been reported and may result from multiple mechanisms. However, few RSA retrieval studies exist. METHODS: We reviewed our RSA database and identified patients with glenosphere dissociation between 1999 and 2013. Prosthesis type, glenosphere size, and contributing factors to dissociation were noted. Five retrieved implants were available for analysis, and evidence of wear or corrosion on the Morse taper was documented. Further, we biomechanically investigated improper Morse taper engagement that may occur intraoperatively as a potential cause of acute dissociation. RESULTS: Thirteen patients with glenosphere dissociation were identified (0.5 months to 7 years postoperatively). Glenosphere size distribution was as follows: 32 mm (n = 1), 36 mm (n = 4), 40 mm (n = 6), and 44 mm (n = 2). Incidence of dissociation was correlated to glenosphere size (P < .001). Taper damage was limited to fretting wear, and there was minimal evidence of taper corrosion. Biomechanically, improper taper engagement reduced the torsional capacity of the glenosphere-baseplate interface by 60% from 19.2 ± 1.0 N-m to 7.5 ± 1.5 N-m. CONCLUSION: We identified several mechanisms contributing to glenosphere dissociation after RSA, including trauma and improper taper engagement. Limited evidence of corrosive wear on the taper interface was identified. Although it is rare, the incidence of glenosphere dissociation was higher when 40- and 44-mm glenospheres were implanted compared with smaller glenospheres (32 and 36 mm), probably because of the larger exposed surface area for potential impingement.

The effects of glenoid wear patterns on patients with osteoarthritis in total shoulder arthroplasty: an assessment of outcomes and value.

BACKGROUND: Despite the success of total shoulder arthroplasty (TSA), concerns remain about the longevity of the implant, in particular, glenoid component survivorship. The purpose of this study was to determine whether preoperative glenoid wear patterns affect clinical outcomes and value in patients undergoing TSA. METHODS: A comparative cohort study was conducted of 309 patients with a total of 344 TSA procedures, performed for primary glenohumeral osteoarthritis. Computed tomography scans were obtained in all patients, with preoperative glenoid wear pattern characterized as either concentric (n = 196; follow-up time, 49.2 months) or eccentric (n = 148; follow-up time, 52.3 months) according to a modified Levine classification. A clinical, radiographic, and economic assessment was performed between the 2 wear patterns. RESULTS: There was no significant difference in American Shoulder and Elbow Surgeons (ASES) score in the concentric group (80.8 ± 20.8) compared with the eccentric group (77.6 ± 21.2) at final follow-up (P = .159). Range of motion and final visual analog scale for pain score were similar between the 2 groups. Radiographic evidence of gross glenoid loosening was significantly lower in the concentric group [11 of 195 (5.6%)] compared with the eccentric group [18 of 147 (12.2%)] (P = .030). Revision rates were similar between the concentric group [4 of 195 (2.0%)] and the eccentric group [3 of 147 (2.0%)]. A value assessment also showed no significant difference between the concentric and eccentric groups [concentric 26.1 vs. eccentric 25.5 (ΔASES score/$10,000 hospital cost) (P = .479)]. CONCLUSIONS: Similar clinical results and value can be expected with both concentric and eccentric glenoid wear patterns in TSA. Concerns arise, however, as the eccentric group demonstrated a more than 2-fold increased rate of glenoid component loosening compared with the concentric group.