Radiographic stage of osteoarthritis or sex of the patient does not predict one year outcome after total hip arthroplasty

Abstract

Objective: To investigate whether patients with severe radiographic osteoarthritis (OA) have a different outcome at one year after total hip replacement than patients with moderate radiographic OA. To investigate sex related differences in preoperative radiographic and self reported status and in postoperative outcome.

Methods: 184 patients (96 women) with a mean age at surgery of 71.4 years (50-92), with primary OA of the hip were investigated preoperatively and six and 12 months postoperatively with two self administered questionnaires, SF-36 and WOMAC. The radiographs were evaluated by two independent radiologists using an atlas. Minimal joint space narrowing, osteophytes, cysts, sclerosis, and deformity were assessed. A summary grade 0-3 was made, based on joint space, where 3 is severe OA. The reference population for SF-36 consisted of 2901 subjects matched for age and sex from the general Swedish population.

Results: 162 patients fulfilled the study criteria. 113 had grade 3, 47 grade 2, and two grade 1 radiographic OA. There was no difference in preoperative or postoperative pain and physical impairment between patients with moderate and severe radiographic OA. There were no sex related differences in preoperative radiographic status, or in postoperative outcome. Neither were any differences in preoperative radiographic status of OA found in patients with previous total hip replacement of the contralateral hip, compared with those who had not been operated on before. All patients, regardless of preoperative radiographic OA stage, showed significant postoperative improvement and at one year achieved a health related quality of life similar to that of the reference group.

Conclusion: The severity of radiographic changes indicating OA often weighs heavily in the surgeon's decision to perform a total hip replacement. Yet, the findings of this study emphasise that the preoperative radiographic stage of OA has no correlation with the postoperative outcome after one year. Furthermore, this study failed to detect any sex related differences in preoperative radiographic and self reported status or in postoperative outcome of hip replacement.

Figure 1

Mean values of SF-36 subscales preoperatively and six and 12 months postoperatively for patients with moderate (grade 2) (n=47) and severe (grade 3) (n=113) radiographic OA. The scale is 0-100, worst to best. PF = physical function; RP = role function physical; BP = bodily pain; GH = general health; VT = vitality; SF = social function; RE = role function emotional; MH = mental health.

Figure 2

Pre- and postoperative mean values of SF-36 data for all patients (n=162) compared with the reference population. PF = physical function; RP = role function physical; BP = bodily pain; GH = general health; VT = vitality; SF = social function; RE = role function emotional; MH = mental health. The scale is 0-100, worst to best.