Abstract
Introduction
There is uncertainty about the relationship between improvement in range of motion (ROM) and functional outcome or patient satisfaction after total hip arthroplasty (THA). Using data from a prospective multi-centre study we investigated this relationship.
Methods
We recorded the Oxford Hip Score (OHS), Merle d'Aubigne and Postel score (MDA) and range of motion (ROM) preoperatively and at one and five years and a patient satisfaction questionnaire at five years. Complete 5 year data were available for 342 patients.
Results
Improvement in ROM between one and five years was significant but minimal (p=0.005, year 1: mean 191(0–280), year 5: mean 191(70–300). Both absolute ROM (year 1, r=0.27; year 5, r=0.40) and ROM gain (r=0.45, 0.59) had a significant linear correlation (p=0.000). ROM improvement and MDA gain at five years had the best association and predicted 34% of the variability of the model. Absolute and ROM gain both had a linear correlation with OHS gain (p=0.001), but their predictive value was poor. ROM gain predicted OHS gain better than absolute ROM (year 1, r= 0.22 vs 0.10; year 5, r= 0.23 vs 0.09). The strongest association was between ROM gain and OHS gain at 5 years that explained 5% of the variability. There was no difference in absolute or ROM gain between those who were satisfied and not with surgery.
Conclusion
There was minimal improvement in ROM after first year. ROM predicted surgeon reported assessment but not patient reported outcome. Relative gain predicted OHS improvement better than absolute ROM but did not affect patient satisfaction. It may be unnecessary to review patients in person to assess ROM after THA.
