Factors predicting postoperative range of motion for anatomic total shoulder arthroplasty

Total shoulder arthroplasty (TSA) has repeatedly been shown to be an effective and durable treatment option for end-stage arthritis with good long-term survivorship. Whereas pain relief is typically the primary goal, improvements in range of motion are typically expected as well. The factors that influence postoperative motion have not been well characterized. The purpose of the study was to examine the factors that influence ultimate postoperative motion after TSA.

A retrospective review was conducted of prospectively collected data of 230 patients with minimum 1-year follow-up after TSA for end-stage arthropathy with an intact rotator cuff. Analysis was focused on factors that may correlate with postoperative measured forward flexion, abduction, external rotation, and internal rotation. Included in this analysis was perception of motion, age, body mass index (BMI), comorbidities (smoking, diabetes, osteoporosis, hypercholesterolemia, inflammatory arthritis, and thyroid disease), and number of comorbidities.

Preoperative motion in all directions was predictive of postoperative motion for forward flexion (R = 0.235; P < .001), abduction (R = 0.363; P < .001), external rotation (R = 0.325; P < .001), and internal rotation (R = 0.213; P = .002). BMI and diabetes both negatively correlated with internal rotation (R = -0.134, P = .40 and R = -0.196, P = .003, respectively). Individual and total number of comorbidities were not predictive of postoperative motion. The patient's perception of preoperative motion also did not correlate with postoperative motion.

Preoperative range of motion before TSA is most predictive of final motion achieved. Individual and total number of comorbidities are not predictive of postoperative motion. Patients with high diabetes and increased BMI have limited postoperative internal rotation.