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Revision hip arthroplasties with use of the modular S-ROM prosthesis.

OBJECTIVE
The aim of this study was to revision hip arthroplasties in ankylosing spondylitis.


MATERIALS AND METHODS
We performed 21 revision hip arthroplasty in 16 patients with ankylosing spondylitis (AS) using S-ROM modular femoral stem. At the final follow-up, all patients were able to ambulate without any walking aids.


RESULTS
The mean Harris hip score improved from 57.2 (35 to 74) pre-operatively to 90.2 points (73 to 100) post-operatively, and the outcome was classified as good or excellent in 17 hips (81%). Fixation of the femoral component was classified as stable with bone ingrowth in 15 hips (71.4%), stable with fibrous ingrowth in 2 hips (9.5%), and radiolucent loosening in 4 hips (19.1%). Five hips developed a pedestal at the tip of femoral component. Femoral osteolysis was found in 3 hips (14.2%): 3 hips in Gruen zones 1 and 7, one hip in zone 7, and two hips in zone 1. One hip underwent acetabular revision because of breakage of polyethylene liner, and the well-fixed femoral component was left in situ. Thigh pain developed in 1 patient (6.2%). Kaplan-Meier survival was 81% at 64 months, with radiographic loosening as an end-point when two hips were at risk.


CONCLUSION
Satisfactory results of midterm clinical and radiographic follow-up can be achieved using S-ROM modular femoral stem for revision of femoral stem in ankylosing spondylitis.