A new 28mm-diameter ceramic-on-ceramic (COC) acetabular bearing couple (Biomet Orthopedics) showed extremely low wear, even under adverse microseparation conditions∗. The wear results are similar or more favorable than those reported for clinical retrievals and wear testing of similar ceramic bearings. A new acetabular shell and ceramic insert design (Biomet) incorporates features to help prevent malalignment during implantation, while still providing secure fixation within the acetabular shell. The incorporation of Biolox® Delta (zirconia toughened alumina, CeramTec) material should provide improved wear resistance over pure alumina ceramics. The goal of this study is to evaluate the wear durability of this system for standard and microseparation testing.Summary Statement
Introduction
A powered, randomised control trial was instigated to evaluate the advantages of subacromial injection of Methylprednisolone over conservative treatment in the management of partial rotator cuff injuries of the shoulder. Consecutive patients with possible partial rotator cuff tears were reviewed at 1 week. Inclusion criteria for a diagnosis of partial rotator cuff tear included; traumatic mechanism, greater tuberosity tenderness, painful arc, and complete resolution of disability post-Bupivicaine block. Exclusion criteria included; age <
16 years, chronic shoulder disease, acromioclavicular tenderness, and abnormal shoulder radiograph. Patients were randomly allocated to receive either 1 immediate subacromial injection of 40mg Methylprednisolone (group S) or no injection (group N). Initial outcomes measured were; visual analogue pain score (0–10) and active abduction (nearest 5°), repeated at 3, 6, and 12 weeks. All patients were instructed in analgesia usage and given identical shoulder exercises. Of 279 patients reviewed over 3 years, 90 met the inclusion criteria (6/90 patients were lost to follow-up). 50 patients were randomised to group S, 40 to group N. Mean pain score improvement at 12 weeks was comparable (S=4.95, N=4.44) (p>
0.1, CI=0.16–0.86). In patients aged >
40 years group S had significantly higher mean improvement in abduction at completion (64.28°) compared to group N (34.63°) (p<
0.02, CI 1.29–58.01). Conversely in patients aged <
40 years group S had lower mean improvements in abduction (40.55°) compared to group N (77.73°), though this was not statistically significant (p=0.1, CI 2.06–72.29) Methylprednisolone injection is more efficacious than conservative treatment alone in some patients. This benefit appears age-dependent and consequently such treatment should be reserved for patients aged >
40 years.
