Iannotti and Williams review the anatomic and biomechanical principles that should govern total shoulder arthroplasty prosthetic design, drawing on quantitative data from normal glenohumeral anatomy to define what implants must reproduce — and where design alone cannot compensate for pathology or technical error.
When selecting humeral head size and glenoid component, remember that restoring the lateral glenohumeral offset requires matching head size to the patient's anatomy (not just canal fit), and that a small deliberate radial mismatch — not perfect conformity — is the biomechanically correct target; a varus stem or inferiorly malpositioned head should be recognized intraoperatively because no head-size adjustment will fully correct the resulting impingement or overstuffing.
Iannotti and Williams review the anatomic and biomechanical principles that should govern total shoulder arthroplasty prosthetic design, drawing on quantitative data from normal glenohumeral anatomy to define what implants must reproduce — and where design alone cannot compensate for pathology or technical error.
When selecting humeral head size and glenoid component, remember that restoring the lateral glenohumeral offset requires matching head size to the patient's anatomy (not just canal fit), and that a small deliberate radial mismatch — not perfect conformity — is the biomechanically correct target; a varus stem or inferiorly malpositioned head should be recognized intraoperatively because no head-size adjustment will fully correct the resulting impingement or overstuffing.