Predicting the underestimation of the femoral offset in anteroposterior radiographs of the pelvis using 'lesser trochanter index': a 3D CT derived simulated radiographic analysis.

We developed 'lesser trochanter index' (LTI) and estimated its accuracy in predicting the underestimation of offset in the anteroposterior (AP) pelvic radiographs. We reconstructed 320 simulated radiographs from the CT scans of 40 adult hips at different rotational projections of 10° increments from 30° internal rotation to 40° external rotation. Underestimation of femoral offset as a percentage was derived from the neck profile angle for all radiographs. Radiographs with an LTI value above 35 were 94% (95% CI, 89%-97%) likely to underestimate femoral offset by more than 5%. Radiographs with LTI between 0 and 30 demonstrated femoral offset within 5% of the true offset (predictive value 100%, CI 87%-100%). LTI could be a useful guide in preoperative templating of hip arthroplasty.

Intratendinous supraspinatus cyst as a cause of shoulder impingement.

We report the case of a 29-year-old gentleman with shoulder impingement. An articular-sided intratendinous supraspinatus cyst was identified as the cause of his symptoms. Arthroscopic cyst debridement resulted in a good outcome at 1-year follow-up. Cysts around the shoulder are a well described pathological entity. They consist of different categories, including intraosseus cysts of the humeral head and glenoid, paralabral cysts and cysts associated with the acromioclavicular joint. Although paralabral cysts that lie intramuscularly or between the muscle bellies have frequently been reported, this is the first report of an intratendinous supraspinatus cyst with an intact rotator cuff. We describe the case, its management and the postsurgical outcome.