Unilateral total hip arthroplasty in bilateral ankylosed hips: A case-series of eight patients of ankylosing spondylitis

Introduction

In approximately one-third to half of patients of ankylosing spondylitis (AS), involvement of the hips may occur with 50–90% of these presenting with bilateral hip involvement. Total hip arthroplasty (THA) in these patients provide mobile hip, which significantly improves their functional capability and lifestyle. Aim of our study was to assess the clinical outcome of unilateral THA in AS patients with bilaterally ankylosed hips in terms of pain, hip mobility, ability to perform functional activities like sitting and walking and radiological evaluation in terms of position of acetabular cup, heterotrophic ossification (HO) and any sign of osteolysis.

Methods

Eight male patients (8 hips), between 25 and 40 years with ankylosed hips and spine in which only unilateral cemented THA was done due to financial constraints, were studied with average follow-up of 18.25 months (Range- 12–30 months). Results were assessed by walking ability, Harris Hip Score (HHS) and radiological findings.

Results

Mean pre-op HHS was 31.3. All these patients were more or less dependent on others for daily activities. None of the patient was able to sit on chair and all were able to walk indoor only. Mean HHS at final follow-up was 76.4. At final follow-up, all the patients could sit comfortably on a chair for more than 1 hour and were walking independently, although with a limp. Radiologically, acetabular cup inclination and anteversion was within Lewinnek’s safe zone in all the patients.

Conclusion

Unilateral cemented THA is a potential option in rehabilitation of patients of AS with bilaterally ankylosed hips, who cannot afford bilateral THA. But these young patients with rigid spine, who are very much dependent upon hip mobility, must be kept under observation to discover complications like loosening and for maintaining hip mobility.