This is a retrospective review of 41 locked posterior shoulder dislocations in 40 patients, treated at two tertiary centers between 1965 and 1982. It addresses three questions: how to make the diagnosis, how to size the impression defect, and which treatment produces the best result based on defect size and dislocation duration.
Missed posterior shoulder dislocation is a classic diagnostic failure, and this paper explains why: a standard AP view looks near-normal because the humeral head sits behind the glenoid in the same sagittal plane as the x-ray beam. Without an axillary view, the diagnosis simply cannot be made radiographically.
When you see a patient after seizure, electroshock therapy, or high-energy trauma with limited external rotation and the shoulder referred as 'frozen' — get an axillary radiograph. Gentle abduction to 20–30° is sufficient to obtain it, even acutely.
Once the diagnosis is confirmed, use axillary radiograph (and CT if needed) to size the impression defect and guide treatment: Defect <20%, duration <6 weeks: attempt closed reduction Defect 20–45%, duration <6 months: lesser tuberosity transfer Defect >45% or duration >6 months: arthroplasty (hemi if glenoid intact, total if glenoid destroyed)
For arthroplasty, reduce humeral component retroversion below the standard 35–40°. Chronic dislocations may require neutral version. Use trial components intraoperatively to dial in the correct version and test stability before final implantation.
This is a retrospective review of 41 locked posterior shoulder dislocations in 40 patients, treated at two tertiary centers between 1965 and 1982. It addresses three questions: how to make the diagnosis, how to size the impression defect, and which treatment produces the best result based on defect size and dislocation duration.
Missed posterior shoulder dislocation is a classic diagnostic failure, and this paper explains why: a standard AP view looks near-normal because the humeral head sits behind the glenoid in the same sagittal plane as the x-ray beam. Without an axillary view, the diagnosis simply cannot be made radiographically.
When you see a patient after seizure, electroshock therapy, or high-energy trauma with limited external rotation and the shoulder referred as 'frozen' — get an axillary radiograph. Gentle abduction to 20–30° is sufficient to obtain it, even acutely.
Once the diagnosis is confirmed, use axillary radiograph (and CT if needed) to size the impression defect and guide treatment: Defect <20%, duration <6 weeks: attempt closed reduction Defect 20–45%, duration <6 months: lesser tuberosity transfer Defect >45% or duration >6 months: arthroplasty (hemi if glenoid intact, total if glenoid destroyed)
For arthroplasty, reduce humeral component retroversion below the standard 35–40°. Chronic dislocations may require neutral version. Use trial components intraoperatively to dial in the correct version and test stability before final implantation.