THE EFFECT OF PRE-OPERATIVE BACK PAIN ON MEDIUM TERM OUTCOME FOLLOWING UNILATERAL PRIMARY TOTAL HIP REPLACEMENT: A 5 YEAR PROSPECTIVE STUDY

Abstract

Introduction: Total Hip Replacement (THR) is an effective procedure that improves Quality of Life (QoL) in patients with hip arthritis. Co-existing back pain is common in these patients. We assessed the impact of back pain on the medium term outcomes of patients undergoing unilateral THR using a disease specific measure, Harris Hip Score (HHS) and a general health questionnaire, Short Form-36 Health Evaluation (SF-36). The SF-36 generates scores on 8 dimensions of QoL; physical functioning (PF), role limitation due to physical problems (RP), role limitation due to emotional problems (RE), social functioning (SF), mental health (MH), energy/vitality (EV), bodily pain (Pain) and general health perception (GHP). It also contains an item requesting information on perceived health change over the past year (CH).

Methods: Between 4th January 1998 and 22nd July 2001, 909 consecutive patients undergoing unilateral THR were entered into a regional arthroplasty database. An audit nurse collected data prospectively. Patients were assessed pre-operatively and demographic details recorded. Patients were asked specifically about the presence or not of back pain. Post-operative follow up was at 6 mnths, 18 mnths, 3 yrs and 5 yrs. At each point the HHS and SF-36 were measured.

There were more females in our study population (61.2% v 38.8%). Statistical analysis was performed for males and females after adjusting for age, body mass index and pre -op scores.

Results: Pre-op, mean HHS and SF-36 score were lower for patients with back pain. Post-THR, patients had overall better outcome scores. Male patients with back pain had significantly lower (P< 0.01) post-THR outcome scores at all time points for HHS, PF, SF and Pain compared to their male peers without back pain. These changes persisted to 5 yrs. This effect was not demonstrated in female patients. The only exception was in the Pain domain of SF-36 where female patients with back pain had lower scores (P< 0.01) than those without back pain.

Conclusion: Patients with back pain obtain significant benefit from unilateral THR in the medium term and this is maintained at 5 yrs. Despite the clinical benefit to the group as a whole, the absolute scores for males with pre-op back pain remain significantly lower than their peers without back pain. Pre-op back pain did not significantly affect outcome in females.