This cadaveric biomechanical study asks whether glenoid component version affects humeral head position and glenoid loading in total shoulder arthroplasty. Six shoulders were tested with the glenoid tilted in 4° steps into ante- and retroversion. It also tested whether adjusting humeral component version could compensate for glenoid malposition.
The practical rule from this paper: fix the glenoid version, not the humeral version. When you face an arthritic shoulder with posterior wear and retroversion, tilting the glenoid component into retroversion parks the humeral head posteriorly and loads the posterior rim. That eccentric load is the same mechanical problem behind the rocking-horse phenomenon that drives early glenoid loosening.
A common bailout is to add humeral antetorsion to compensate for glenoid retroversion. This study shows that trick does not work because humeral rotation keeps the same center of rotation and does not redistribute glenoid force. The takeaway for planning: correct glenoid version toward neutral with reaming or grafting when feasible, since version cannot be rescued from the humeral side.
Remember this is a 6-specimen proof-of-principle cadaver study, so it demonstrates the mechanism rather than proving clinical loosening rates.
This cadaveric biomechanical study asks whether glenoid component version affects humeral head position and glenoid loading in total shoulder arthroplasty. Six shoulders were tested with the glenoid tilted in 4° steps into ante- and retroversion. It also tested whether adjusting humeral component version could compensate for glenoid malposition.
The practical rule from this paper: fix the glenoid version, not the humeral version. When you face an arthritic shoulder with posterior wear and retroversion, tilting the glenoid component into retroversion parks the humeral head posteriorly and loads the posterior rim. That eccentric load is the same mechanical problem behind the rocking-horse phenomenon that drives early glenoid loosening.
A common bailout is to add humeral antetorsion to compensate for glenoid retroversion. This study shows that trick does not work because humeral rotation keeps the same center of rotation and does not redistribute glenoid force. The takeaway for planning: correct glenoid version toward neutral with reaming or grafting when feasible, since version cannot be rescued from the humeral side.
Remember this is a 6-specimen proof-of-principle cadaver study, so it demonstrates the mechanism rather than proving clinical loosening rates.