Neer's prospective analysis of 40 revision humeral head and total shoulder arthroplasties in 36 patients. It catalogs why primary shoulder replacements fail and how the authors approached revision surgery. The central theme: shoulder arthroplasty depends on a reconstructed rotator cuff and preserved deltoid, not a mechanical fulcrum.
The core teaching point: the shoulder is not the hip. Its socket is small and flat and its ligaments are loose, so the rotator cuff must provide both stability and power.
This is why fixed-fulcrum constrained designs failed. They tried to substitute a mechanical hinge for the cuff, but the deltoid alone cannot power external rotation, and the mobile impact-loaded joint tore the implant from the scapula.
For a resident, the decision rules are concrete. Restore humeral length within 2.0 cm to keep the deltoid tensioned. Protect the anterior deltoid with a deltopectoral approach and avoid radical acromionectomy. Reserve arthrodesis for infection or combined deltoid-plus-cuff loss. Everything else can go to an unconstrained total shoulder.
The broader lesson is that revision outcomes are capped by accumulated muscle damage, bone loss, and scar, so the best revision is a good primary arthroplasty done right the first time.
Neer's prospective analysis of 40 revision humeral head and total shoulder arthroplasties in 36 patients. It catalogs why primary shoulder replacements fail and how the authors approached revision surgery. The central theme: shoulder arthroplasty depends on a reconstructed rotator cuff and preserved deltoid, not a mechanical fulcrum.
The core teaching point: the shoulder is not the hip. Its socket is small and flat and its ligaments are loose, so the rotator cuff must provide both stability and power.
This is why fixed-fulcrum constrained designs failed. They tried to substitute a mechanical hinge for the cuff, but the deltoid alone cannot power external rotation, and the mobile impact-loaded joint tore the implant from the scapula.
For a resident, the decision rules are concrete. Restore humeral length within 2.0 cm to keep the deltoid tensioned. Protect the anterior deltoid with a deltopectoral approach and avoid radical acromionectomy. Reserve arthrodesis for infection or combined deltoid-plus-cuff loss. Everything else can go to an unconstrained total shoulder.
The broader lesson is that revision outcomes are capped by accumulated muscle damage, bone loss, and scar, so the best revision is a good primary arthroplasty done right the first time.