Abstract
Introduction
Instability accounts for one third of revision total hip arthroplasty(rTHA) performed in the United Kingdom. Removal of well-fixed femoral stems in rTHA is challenging with a risk of blood loss and iatrogenic damage to the femur. The Bioball Universal Adaptor (BUA) (Merete, Germany), a modular head neck extension adaptor, provides a mechanism for optimisation of femoral offset, leg length and femoral anteversion. This can avoid the need for femoral stem revision in selected cases. There is a relative paucity of clinical data available with the use of this device.
Aim
The aim of this study is to present the clinical results and rate of instability following revision with this head neck adaptor at a minimum of two years' follow up.
Patients and Methods
A review of our prospectively collected database was performed. All patients treated with the Bioball device were included. Clinical and radiologic review were performed pre- and post-surgery. Specific enquiry for instability was made. The Oxford Hip Score (OHS), Euro-Quol (EQ-5D) score and WOMAC scores were calculated pre-and post-operatively. Complications were recorded. Statistical analysis using a Students t-test with a significance level of p<0.05 was considered to be statistically significant.
Results
Thirty-two rTHA procedures were performed using the Bioball device between 2013 and 2016. Four patients did not wish to complete post-operative questionnaires. These had no complaints regarding their revised hips and were functioning well. Two patients (2/28, 7%) complained of recurrent dislocations following their rTHA procedure. One patient complained of instability but no dislocation. The median pre-operative EQ-5D was 0.195 (range −0.07 to 0.85), OHS was 20 (range 5 to 43) and WOMAC was 29.8 (range 15.5 to 52.3). The median EQ-5D was 0.85 (range 0.59 to 1), OHS was 39 (range 21 to 48) and WOMAC was 91.1 (range 44.5 to 99.2) at final follow up.
There were significant improvements in the EQ-5D (p = 0.0009), OHS (p = 0.0004) and WOMAC (p = 0.0001).
Conclusion
The Bioball Head Neck Adaptor is associated with significant functional improvement and relatively low dislocation rates in revision THA. It is a viable option for use in the revision setting.
