Arthroscopic and open partial arthroplasty for the treatment of focal grade IV cartilage defects of the humeral head.

Introduction: Focal Outerbridge grade IV cartilage defects of the proximal humerus may lead to pain and an impaired shoulder function. In cases of failed operative or conservative treatment options such as intraarticular injections or arthroscopic microfracturing of the subchondral bone, partial arthroplasty of the humeral may restore the articular surface of the humeral head without altering the anatomy. This study evaluates mid-term results of open and arthroscopic partial resurfacing of the humeral head in the context of focal grade IV cartilage defects.

Methods: Eighteen patients (f = 3, m = 15, mean age = 57.7 years) out of 22 patients were available for follow-up after 65 (24-116) months. Thirteen patients were treated with a partial humeral head prosthesis in an open technique and five patients received a partial humeral head prosthesis in an arthroscopic technique. The patients were followed-up clinically using the Constant-Score, the ASES Score as well as the range of motion. Plain radiographs (anterior-posterior and axial view) were carried out for radiologic assessment.

Results: At follow-up the mean CS rated 79.5. The mean ASES Score was 85.8 points. Mean active forward flexion measured 163.8°, while mean active abduction was 160.0°. The average pain level on a visual analogue scale (VAS) made out 0.7 out of 10. Patients treated with an arthroscopically implanted prosthesis achieved a mean CS of 88.8 points and a mean ASES Score of 92.6 points. The patients with openly implanted prosthesis had a CS of 75.3 points and an ASES Score of 83 points. There were no intraoperative or immediate postoperative complications. Until the final follow-up one patient needed to be converted to total shoulder arthroplasty due to progressive glenohumeral osteoarthritis. Nine patients (50%) showed progressive glenohumeral osteoarthritis. Aseptic loosening of the implants was not observed.

Conclusion: Partial arthroscopic or open arthroplasty of the humeral head is related to good functional results after mid-term follow-up. Resurfacing of the humeral head is a safe procedure without any implant-related complications. There is a risk for progression of glenohumeral osteoarthritis, which may require surgical revision with conversion to anatomic shoulder arthroplasty.

Level Of Evidence: Level IV (retrospective study).