Precision of novel radiological methods in relation to resurfacing humeral head implants: assessment by radiostereometric analysis, DXA, and geometrical analysis

Background

Resurfacing humeral head implants (RHHI) are used to preserve bone stock and restore normal anatomy in the osteoarthritic shoulder joint. The purpose of this study was: (1) to describe the use of novel radiological methods in relation to evaluation of RHHI; (2) to estimate the precision of these methods; and (3) to present preliminary clinical and radiological results at 6 months follow-up after Copeland and Global Cap RHHI.

Methods

Twenty-one patients (10 females) at a mean age of 64 (39–82) years and with shoulder osteoarthritis were randomized to a Copeland (n = 11) or Global C.A.P (n = 10) RHHI. Migration of the RHHI was analyzed with radiostereometric analysis (RSA), and bone mineral density (BMD) was measured with dual energy X-ray absorptiometry (DXA). The length of gleno-humeral offset (LGHO) was measured on radiographs. The patients were followed clinically with questionnaires.

Results

Precision of the radiological methods was high for the LGHO and acceptable for RSA and for DXA. At 6 months, shoulder function had improved significantly for both RHHI groups. LGHO increased significantly for the Copeland RHHI and was slightly reduced for the Global C.A.P. RHHI. The implant migration and BMD change around the implant from baseline until 6 months follow-up was comparable for both RHHI.

Conclusion

Radiostereometric analysis and DXA can be used for evaluation of RHHI, but expectedly with a lower precision as compared to standards of TKA or THA. Geometric analysis of the prosthetic shoulder is precise. We interpret that the early radiological and clinical results of the two RHHI are comparable.