Purpose of the study: The anterior rim of the arthroplasty cup can overhang the bone in certain situations: oversized cup, insufficient anteversion, insufficient ace-tabular reaming, cylindrospherical reaming overriding the acetabular opening. The straight or concave shape of the anterior wall of the acetabulum also affects prosthetic overhang. The purpose of this anatomic study was to use a navigation system to quantify, in vitro, the height of the iliopubic psoas notch.

Material and methods: Sixty-eight acetabuli from 34 cadaver pelvi free of osteoarthritis (13 male and 21 female) were analyzed using the Stryker™ hip navigation system. Morphological data were collected for mathematical processing which defined the diameter and the center of the articular surface.

Results: Considerable intra- and inter-individual differences in the shape of the acetabular rim were noted and quantified, particularly concerning the psoas notch. When the lateral view of the acetabular rim is projected onto a plane it produces a succession of three summits and three valleys explaining the difficulty encountered in obtaining a precise mean plane for the acetabular opening.

Discussion: More or less pronounced protrusion of the cup could explain potentially painful anterior impingement of the psoas, especially for certain types of acetabular morphology.

Purpose: Fractures of the upper humerus are frequent in elderly persons. While 80% are generally treated orthopaedically, about 20% are complex complicating treatment. Osteosythesis has given disappointing results due to the poor bone quality. Simple humeral arthroplsaty with simple tuberosity fixation could be a solution.

Material and method: Between 1993 and 1998, 50 patients, 39 women and 11 men, mean age 74.5 years (51–90) were treated for cephalotuberosity fractures with cemented humeral arthroplasty. The dominant side was involved in 80% of the cases; there were 39 fractures with four fragments in the Neer classification with seven associated with anterior dislocation, eleven with three fragments including two associated with anterior dislocation. Three patients had a neurological complication: elongation of the brachial plexus in one and irritation of the ulnar nerve in two. Mean delay to surgery was 2.4 days. Thirty-seven patients were operated via the superolateral approach, 13 via the deltopectoral approach. A total of 37 Neer prostheses were implanted and 13 Guepar prostheses. Three patients had a full thickness cuff tear, sutured in the same operative time. The glenoid cavity was healthy in all cases. the upper limb was immobilised elbow against thorax using an abduction brace for 2& days. Active rehabilitation exercises began during the sixth week.

Results: Mean follow-up was 2.5 years. Twelve patients had died, four were lost to follow-up and six could not be examined due to an alteration of their cognitive functions. The analysis thus concerned 28 patients. The mean absolute Constant score at last follow-up was 47 points, with a weighted score of 70 points. Outcome was good in nine cases, fair in eight, and poor in eleven. 86% of the shoulders were pain free. Overall active mobility was: antepulsion 80.5°, abduction 77°, external rotation 20°; 18 patients had internal rotation at L5or more. Radiographically, there was a tuberosity lysis in eight patients and a defective trochiter callus in nine. No changes in the humeral component cementing were observed. The trochiter lever arm was 28 cm, 92.7% of the offset measured on the healthy side. The distance between the apex of the head and the trochiter was 10 mm on the average. Glenoid wear was noted in ten cases. There was no evidence of periprosthetic ossification. Mean ES was 9.9 mm.

Discussion: Pain relief was good. Amplitudes were correlated with age, the quality of the tuberosity fixation, and the duration of rehabilitation (> 1 year). An associated dislocation did not appear to have a deleterious effect. The approach used or offset did not appear to affect results.

Conclusion: Our patients achieved good pain relief but lost a certain degree of mobility, similar to findings reported in the literature. The main prognostic factors are the quality of the tuberosity reconstruction and patient compliance to rehabilitation.