Isometric strength, range of motion, and impairment before and after total and reverse shoulder arthroplasty

Medicare Part A provides similar resources for coverage of inpatient hospitalization costs for patients treated with total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA). This is based on an assumption that TSA and RSA are used to treat similar patient populations with comparable disease severity. However, no objective clinical information is available to support this resource allocation. The purpose of this study is to quantify the disease severity and subsequent improvement from primary TSA, primary RSA, and revision arthroplasty (TSA and RSA).

From March 2004 through May 2006, 174 shoulders (87 primary TSA, 55 primary RSA, and 32 revision cases) were prospectively studied using Biodex (Biodex Medical Systems, Shirley, NY, USA) isometric strength and standardized video range of motion measurements performed by an independent third-party observer at 1 week before surgery and at an average of 49 months (range, 32-69 months) postoperatively. Patient impairment ratings were calculated using the Florida Impairment Guidelines.

Primary TSA had the lowest average preoperative impairment (21%), and revision arthroplasty had the highest (28%). All patients demonstrated improvement in the parameters tested. At an average 49 months, all 3 groups demonstrated a similar reduction in impairment ratings (TSA: 21% to 10%; RSA: 25% to 15%; revision arthroplasties: 28% to 20%).

There are distinct differences in preoperative disease severity among patients undergoing primary TSA, primary RSA, and revision arthroplasty. Greater impairment is evident in patients undergoing a revision arthroplasty. However, all groups may be expected to achieve improvements and maintain these improvements 4 years postoperatively.