Purpose: The purpose of this multicentric study was to report results obtained with the Aequalis system using the simple humeral or total prosthesis, at at least two years follow-up in patients with shoulder joint degeneration and non-repairable rotator cuff tears.
Material and methods: Sixty-eight Aequalis arthroplasties were performed between 1992 and 1998. Outcome was assessed on the basis of the Constant score and radiological findings. Female gender predominated (78%) in this series with a mean age of 72 years. There were 62 simple humeral implantations and six total shoulder arthroplasties. The deltopectoral approach was used in 63 cases and the superior approach in five. All stems and sockets were cemented. There were no neurological or infectious complications.
Results: Two humeral stem implants were failures and required revision with a Grammont prosthesis. There was also one reoperation for arthrolysis with preservation of the implant; the outcome was fair.
Functional outcome: Sixty-six patients were reviewed with a mean follow-up of 45 months. All implantations except one were performed to achieve pain relief. The absolute Constant score improved by 20 points (from 25 to 46) with a 7-point gain for pain (3 to 10), a 20° gain for active elevation, an 18° gain for external rotation, and a 0.4 point gain for force. Pain relief was greater with total prostheses. Only five patients stated they were dissatis-fied with the outcome despite the fact that 18 reported significant persistent pain. The Constant score was analysed as a function of follow-up, size of the humeral head, and preoperative morphology of the glenoid surface. Radiological outcome: Certain loosening was recognised for one glenoid and one humeral stem. Among 52 shoulders with strictly identical radiological results, 33 exhibited deterioration either for the vault or the glenoid or both, with no effect on the Constant score.
Discussion: In this indication the Adqualis prosthesis is implanted to achieve a “limited” objective: pain relief. The deltopectoral approach is preferable in order to preserve elements inhibiting superior migration of the humerus (in a parallel study, the absence of these elements explains the poor outcome observed in 3 out of 9 patients). Unlike other series, the present series exhibited a significant effect of a type E2 biconcave glenoid surface. The pain score was better with total shoulder prostheses than with humeral stems alone and four of the six glenoid sockets remained perfectly fixed. The long-term outcome of these glenoid surfaces remains unknown so it would be inappropriate to advise systematic use. Clinical outcome did not show any deterioration over time despite deterioration of the vault, the glenoid, or both. Indications for non-constrained pros-theses should however be retained with caution due to open questions concerning long-term outcome, particularly for shoulders which have already been operated on or with type E2 glenoids. Considering these reservations, the Aequalis prosthesis has reached, at nearly five years follow-up, the assigned objectives: significant pain relief, satisfactory overall shoulder function.
