WHY DO THOSE PATIENTS WITH A LOW-PRE-OPERATIVE OXFORD HIP SCORE UNDERGO HIP ARTHROPLASTY?

Abstract

Introduction: The Oxford hip score (OHS) instrument is used to assess pain and disability before and after hip arthroplasty and may be used as a standard for auditing pre and post-operative patients. It has been suggested that patients with a low pre-operative hip score (< 25th percentile) should be carefully assessed before surgical management is employed. This study aimed to determine the factors that influence a surgeon’s decision to undertake hip arthroplasty in patients with a low pre-operative hip score.

Methods: All patients who underwent hip arthroplasty over a two month period (n=121) were included. Of these, four pre-operative OHS questionnaires were missing. The remaining (117) were validated and those scoring below the published 25th percentile (58.3%) were selected (n=35), termed the ‘low-group’. Individual OHS responses scored 0–4 were examined (0 = no impairment and 4 = worst impairment) and the proportional differences between the responses for this group and the remaining 75% were investigated. The pre-operative radiographic Tönnis stage of osteoarthritis was determined.

Results: The median cohort OHS was 68.8% (IQR = 50–79%). Of the questions that scored highly, 59% were purely pain related, 14% function and 27% both. 66% of patients experienced moderate/severe pain and 31% suffered night pain. The ‘low-group’ never scored 4 (worst impairment) on questions concerning washing, transport, shopping, stairs and work. However, 57% scored 4 on questions encompassing a pain component. In all questions except donning socks and walking, the proportion of 4 in the ‘low-group’ was significantly different to the remainder of the cohort. Tönnis grade 3 (osteophytes and advanced loss of joint space) osteoarthritis predominated (49%).

Conclusion: Arthroplasty in patients with low pre-operative OHS is influenced mainly by pain affecting quality of life. Half of these patients also have advanced features of osteoarthritis on radiographic assessment despite the low scores.