This prospective in vivo study used CT-based 3D models plus optical motion capture to compare scapulothoracic alignment in seven patients with unilateral Walch type B glenohumeral osteoarthritis against their healthy contralateral shoulders. It asks whether the arthritic shoulder shows altered resting scapular position or dynamic scapular malalignment during motion.
When you evaluate a Walch type B osteoarthritic shoulder, do not expect a visibly malpositioned scapula at rest. This study shows resting scapulothoracic distances are normal. The abnormality is dynamic. During internal rotation, the arthritic scapula tilts anteriorly about 15° more than the healthy side, likely to compensate for a stiff glenohumeral joint.
That matters because sustained excess anterior tilt narrows the subacromial space and tightens the posterior capsule, mechanisms linked to impingement, cuff tendinopathy, and pain. The authors frame the malalignment as a consequence of glenoid erosion rather than its cause, and note it could in turn potentiate further posteroinferior erosion.
Appreciate the caveat: this is seven patients using a novel skin-marker plus CT technique, so most ROM differences did not reach significance. Treat it as hypothesis-generating for the scapula's role in type B disease, not as a management-changing result.
This prospective in vivo study used CT-based 3D models plus optical motion capture to compare scapulothoracic alignment in seven patients with unilateral Walch type B glenohumeral osteoarthritis against their healthy contralateral shoulders. It asks whether the arthritic shoulder shows altered resting scapular position or dynamic scapular malalignment during motion.
When you evaluate a Walch type B osteoarthritic shoulder, do not expect a visibly malpositioned scapula at rest. This study shows resting scapulothoracic distances are normal. The abnormality is dynamic. During internal rotation, the arthritic scapula tilts anteriorly about 15° more than the healthy side, likely to compensate for a stiff glenohumeral joint.
That matters because sustained excess anterior tilt narrows the subacromial space and tightens the posterior capsule, mechanisms linked to impingement, cuff tendinopathy, and pain. The authors frame the malalignment as a consequence of glenoid erosion rather than its cause, and note it could in turn potentiate further posteroinferior erosion.
Appreciate the caveat: this is seven patients using a novel skin-marker plus CT technique, so most ROM differences did not reach significance. Treat it as hypothesis-generating for the scapula's role in type B disease, not as a management-changing result.