This biomechanical study quantifies how humeral and glenoid component version independently affect resistance to anterior dislocation in reverse shoulder arthroplasty. A mechanical testing machine measured the stability ratio (peak dislocation force / compressive load) across all version combinations in both 90° abduction and the resting arm position. The goal was to generate evidence-based positioning guidelines to reduce the high rate of dislocation after reverse shoulder replacement.
When planning a reverse shoulder arthroplasty, the instinctive move of placing the humeral component in 20° retroversion — mimicking native humeral version. Is actually one of the worst stability configurations available.
This study gives you a clear decision rule: position the humeral component in neutral or slight anteversion to maximize anterior stability. Each 10° of anteversion buys more than 20% improvement in the stability ratio.
For the glenoid, you have real flexibility. Anywhere from 10° retroversion to 20° anteversion is biomechanically acceptable. Use that range to chase the best bone stock and screw fixation rather than chasing a stability target.
The hard stop is glenoid retroversion beyond 10°: that threshold triggers a statistically significant stability drop in the resting position, where the reverse prosthesis is already at its most vulnerable. In patients with posterior glenoid bone loss exceeding 10°, restore version rather than accept retroversion.
This biomechanical study quantifies how humeral and glenoid component version independently affect resistance to anterior dislocation in reverse shoulder arthroplasty. A mechanical testing machine measured the stability ratio (peak dislocation force / compressive load) across all version combinations in both 90° abduction and the resting arm position. The goal was to generate evidence-based positioning guidelines to reduce the high rate of dislocation after reverse shoulder replacement.
When planning a reverse shoulder arthroplasty, the instinctive move of placing the humeral component in 20° retroversion — mimicking native humeral version. Is actually one of the worst stability configurations available.
This study gives you a clear decision rule: position the humeral component in neutral or slight anteversion to maximize anterior stability. Each 10° of anteversion buys more than 20% improvement in the stability ratio.
For the glenoid, you have real flexibility. Anywhere from 10° retroversion to 20° anteversion is biomechanically acceptable. Use that range to chase the best bone stock and screw fixation rather than chasing a stability target.
The hard stop is glenoid retroversion beyond 10°: that threshold triggers a statistically significant stability drop in the resting position, where the reverse prosthesis is already at its most vulnerable. In patients with posterior glenoid bone loss exceeding 10°, restore version rather than accept retroversion.