Anatomic total shoulder arthroplasty with stemless humeral component, nonspherical head, and inlay glenoid: clinical outcomes at mean 4.4-year follow-up

Background

Limitations of traditional stemmed anatomic total shoulder arthroplasty (aTSA) with a spherical head and onlay glenoid include 1) inaccurate replication of native nonspherical humeral head kinematics, 2) substantial bone resection, and 3) susceptibility to glenoid loosening. Our purpose was to examine the outcomes of stemless aTSA with a nonspherical head and inlay glenoid.

Methods

Sixty patients (63 shoulders) with end-stage glenohumeral osteoarthritis were treated by a single surgeon. The study population was limited to 22 patients/25 shoulders (13 male, 12 female; mean age 65.6 years) with 2-year minimum follow-up (mean 51.8 months) subdivided into 2 groups by age. The young group included 5 patients/5 shoulders (3 male, 2 female; mean age 52.2 years; mean follow-up 62.4 months), while the elderly group included 17 patients/20 shoulders (10 male, 10 female; mean age 68.9 years; mean follow-up 49.2 months). At the final follow-up, patient satisfaction and complications were evaluated and the Constant-Murley, American Shoulder and Elbow Surgeons, and SF-36 scores were compared to preoperative values. First postoperative radiographs were compared to the final follow-up for signs of gross loosening, implant tilt, subsidence, and periprosthetic radiolucency.

Results

No humeral shaft fractures, infections, glenoid/humeral component loosening, radiolucencies, shoulder dislocations, or neurovascular complications were encountered. No reoperations or revisions were performed. The entire study population (25 shoulders) showed significant increases in the Constant score (47.4-82.8, P < .001), American Shoulder and Elbow Surgeons score (36.9-88.1, P < .001), and all components of the SF-36 score (P < .014) except general health perceptions (P = .490), role imitations (emotional) (P = .232), and mental health (P = .746), with a 95% patient satisfaction rate. There were no significant differences between the young and elderly groups in any outcomes (P > .107).

Conclusion

Our results suggest that stemless aTSA performed with a nonspherical humeral head and inlay glenoid is a safe and effective treatment for glenohumeral osteoarthritis in both young and elderly patients. However, longer term studies with larger patient populations will be required for corroboration.