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