The association of patient characteristics and surgical variables on symptoms of pain and function over 5 years following primary hip-replacement surgery: a prospective cohort study

OBJECTIVES: To identify patient characteristics and surgical factors associated with patient-reported outcomes over 5 years following primary total hip replacement (THR).DESIGN: Prospective cohort study.SETTING: Seven hospitals across England and Scotland.PARTICIPANTS: 1431 primary hip replacements for osteoarthritis.MAIN OUTCOME MEASURES: The Oxford Hip Score (OHS) was collected preoperatively and each year up to 5 years postoperatively. Repeated measures such as linear regression modelling are used to identify patient and surgical predictors of outcome and describe trends over time.RESULTS: The majority of patients demonstrated substantial improvement in pain/function in the first year after surgery-between 1 and 5 years follow-up, there was neither further improvement nor decline. The strongest determinant of attained postoperative OHS was the preoperative OHS-those with worse preoperative pain/function had worse postoperative pain/function. Other predictors with small but significant effects included: femoral component offset-women with an offset of 44 or more had better outcomes; age-compared to those aged 50-60, younger (age <50) and older patients (age >60) had worse outcome, increasing body mass index (BMI), more coexisting diseases and worse Short Form 36 mental health (MH) was related to worse postoperative pain/function. Assessment of change in OHS between preoperative and postoperative assessments revealed that patients achieved substantial and clinically relevant symptomatic improvement (change), regardless of variation in these patient and surgical factors.CONCLUSIONS: Patients received substantial benefit from surgery, regardless of their preoperative assessments and surgical characteristics (baseline pain/function, age, BMI, comorbidities, MH and femoral component offset). Further research is needed to identify other factors that can improve our ability to identify patients at risk of poor outcomes from THR surgery