Monday, April 4, 2011

Shoulder arthritis articles from March Issue of the Journal of Shoulder and Elbow Surgery

In the March issue of the Journal of Shoulder and Elbow Surgery, there are four articles that relate to the topic of shoulder arthritis.

The first, by our shoulder fellows Deana Mercer and Matt Saltzman, A reproducible and practical method for documenting the position of the humeral head center relative to the scapula on standardized plain radiographs, demonstrates the remarkably consistent relationship between the center of rotation of the shoulder joint and the bony anatomy of the scapula and the consistent change in this relationship in a condition known as rotator cuff tear arthropathy(see below). The center of rotation forms the basis for the mechanics of the shoulder in health, in arthritis, and with shoulder joint replacement.

Bonnevialle et al in an article entitled Hemiarthroplasty for osteoarthritis in shoulder with dysplastic morphology point to the hazards of attempting a total shoulder replacement in cases where the anatomy of the shoulder is distorted by abnormal bony development - dysplasia. Instead they recommend the use of a hemiarthroplasty - using the humeral component alone.

Walch et al report on Results of a convex-back cemented keeled glenoid component in primary osteoarthritis: multicenter study with a follow-up greater than 5 years. These authors analyzed 333 total shoulder replacements for osteoarthritis performed at four European centers using a 'third generation' unconstrained, cemented implant, Aequalis (Tornier). While over 90% of the patients were satisfied with the results and the revision rates were low, the authors noted a dramatic increase in the x-ray evidence of glenoid component loosening after five years, such that half of the shoulders showed evidence of loosening at 10 years (see especially their figure 3). The discussion of this paper provides a nice review of the issues related to failure of the glenoid component in total shoulder replacement.

Finally, Morman et al describe Arthroscopic tissue biopsy for evaluation of infection before revision arthroplasty build on the finding of our shoulder fellow, Amy Franta, in her article The complex characteristics of 282 unsatisfactory shoulder arthroplasties. in which it was recognized that patients with shoulder pain after joint replacement may have a low grade infection - for example with P. acnes or S. epidermidis - even though there were none of the usual manifestations of fever, redness, or joint tenderness. We now recognize the importance of holding cultures obtained at the time of revision arthroplasty for over two weeks. Morman reported two such cases diagnosed using arthroscopic biopsy. Specimens from each grew P. acnes at 14 days after surgery. The discussion contains a nice review of the challenges of making this diagnosis.


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