What Factors are Associated With Clinically Important Improvement After Shoulder Hemiarthroplasty for Cuff Tear Arthropathy?

Jeremy S Somerson, Patrick Sander, Kamal Bohsali, Ryan Tibbetts, Charles A Rockwood, Michael A Wirth

In selected patients with a desire to maintain activity levels greater than those recommended after reverse total shoulder arthroplasty, hemiarthroplasty remains an option for treatment of cuff tear arthropathy (CTA). However, given the relatively small case series that have been reported to date, little is known regarding which patients will show functional improvement after this surgery. We asked: What factors are associated with achieving the minimum clinically important difference in the simple shoulder test (SST) after hemiarthroplasty for cuff tear arthropathy? Between 1991 and 2007, two surgeons at one academic center performed 48 shoulder hemiarthroplasties for CTA. No patients were known to have died before data collection, and of those not known to have died, 42 (88%) were available for followup at a mean of 48 months (range, 24-132 months). During that time, the general indications for this approach were glenohumeral arthritis with superior decentering of the humeral head. The majority of the patients with CTA were treated nonoperatively with patient-directed physical therapy and other modalities. A total of 42 patients (42 shoulders; 24 males and 18 females) with CTA were treated with hemiarthroplasty and followed for a mean of 48 months (range, 24-132 months). This is a retrospective study that made use of a longitudinally maintained database, which included physical examination of ROM, the SST, VAS, and standardized radiographs. At latest followup, 33 of 42 patients achieved a clinically important percentage of maximum possible improvement (%MPI) in SST score, defined as an improvement of 30% of the total possible improvement on the 12-point scale (with higher scores representing better results). Intraoperative findings of a rotator cuff tear limited to the supraspinatus and infraspinatus (odds ratio [OR], ∞; 95% CI, 2.01 to ∞; p = 0.020) and limited preoperative external rotation (15° [range, -40° to 45°] vs 35° [range, 20°-45°], OR, 0.71; 95% CI, 0.38-0.90; p < 0.001) were associated with achieving the defined minimum functional improvement (30% of MPI) on multivariate analysis. Preoperative active elevation (p = 0.679) and use of a CTA-specific implant (p = 0.707) were not significantly associated with achievement of 30% of MPI. Patients with intact teres minor and subscapularis tendons and patients with lower preoperative external rotation had a better prognosis for achieving a clinically important percentage of MPI at short-term followup. Although some patients were followed for more than 10 years, the majority were followed for fewer than 5 years; future studies will need to determine whether these early functional results are maintained for longer periods. Level III, therapeutic study.