Background: Various radiographic measurements that describe humeral head coverage by the acromion and the effect on rotator cuff pathology have been reported. This study aimed to describe and validate a new radiographic measurement, the acromiohumeral centre edge angle (ACEA). Methods: We compared the ACEA on computed tomography (CT) and plain X-ray to determine whether X-ray is accurate for measuring this angle. We then compared the results from this control population with 107 patients with acute rotator cuff tears. We compared functional outcomes in rotator cuff tear patients to determine whether the ACEA has any effect on outcome after surgery. An intra-and inter-observer variability analysis was performed and we compared the ACEA to the acromial index (AI) on rotation X-rays. Results: The ACEA was comparable on CT and plain X-ray and was most accurate when true anteroposterior glenohumeral X-rays were used (15.94 vs. 15.87 on CT, p ¼ 0.476). The ACEA showed high intra-and inter-observer reproducibility and was unchanged on internal and external rotation X-rays (20.48 vs. 20.47, p ¼ 0.842), whereas the AI was significantly different (0.74 vs. 0.70, p < 0.001). The ACEA was significantly higher in our rotator cuff tear patients than the control population (23.9vs. 16.6 , p < 0.001), although a higher ACEA was not associated with poorer outcomes. Conclusion: The ACEA is a valid measurement for describing humeral head coverage by the acromion and can be accurately measured on plain radiographs with good reproducibility. It is unaffected by shoulder rotation and was significantly higher in patients with acute rotator cuff tears.
Background: Both cruciate retaining (CR) and posterior stabilized (PS) implants are commonly used for primary total knee arthroplasty. There is evidence to support improved range of motion in PS knee replacements, but there is no evidence showing functional superiority. The aim of this study was to compare functional outcomes between CR and PS knee replacements. Patient and methods: Prospectively collected regional joint registry data were used to compare preoperative and postoperative one, 5-and 10-year Oxford and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores in 1287 primary total knee replacements. Differences in functional scores between CR and PS knees were calculated. Results: The PS group had better functional scores than the CR group at baseline (mean Oxford score 15.59 vs. 14.52 (p ¼ 0.026) and mean WOMAC score 59.51 vs. 62.35 (p ¼ 0.012)), at 1 year postoperatively (mean Oxford score 37.94 vs. 36.63 (p ¼ 0.015) and mean WOMAC score 16.20 vs. 19.73 (p ¼ 0.001)) with a similar trend at 5 years postoperatively (mean Oxford score 39.66 vs. 38.50 (p ¼ 0.054) and mean WOMAC score 16.89 vs. 18.83 (p ¼ 0.131)). There was no difference in the overall functional improvement between the PS and CR groups at 1, 5, or 10 years. WOMAC subcomponent scores showed greater improvement in stiffness; 3.76 versus 3.36 (p ¼ 0.012) in PS knees at 1 year postoperatively. No significant differences were observed at 5 or 10 years. Conclusions: PS knee replacements showed greater improvement in stiffness at 1 year postoperatively. There was no difference observed at 5 or 10 years postoperatively. PS knees had better functional outcomes at 1 year with a similar trend at 5 years postoperatively. Level of evidence: III.
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