SOUTHAMPTON, UK—The benefits of total hip arthroplasty on physical function are substantial and long-lasting especially in osteoarthritis (OA) patients with more pronounced X-ray damage, finds a new 8-year study in the December issue of Arthritis Care & Research.¹ The surgery does not, however, provide such durable improvements in terms of vitality or mental health, the study shows.

"Our findings add to the accumulating evidence that the benefits for physical functioning are sustained in the longer term, and they suggest that those benefits are greatest in the patients who have the most severe radiographic changes of OA before surgery," conclude the researchers led by Janet Cushnaghan, MSc, MCSP, of the University of Southampton in the UK.

Improvements in physical function hold 8 years later

Dr. Cushnaghan and colleagues followed 282 OA patients from two English health districts for approximately 8 years after total hip arthroplasty and matched them with 295 controls selected from the general population. Researchers analyzed baseline data on sex, age, comorbidity, body mass index (BMI), and short form 36 (SF-36) functional status. They also graded the preoperative radiographic severity of the OA. They reassessed functional status by mail during follow-up.

In general, patients who underwent total hip arthroplasty reported a median improvement of 10 points in SF-36 score for physical functioning. By contrast, there was a median deterioration of 10 points in controls. "Even when allowance is made for possible confounding effects, the long-term improvement in the physical functioning of the cases is striking when set against the decline that occurred in controls," the authors write.

Change in physical functioning was significantly worse in women and at older ages among both cases and controls.

OA patients with high Croft grades should get priority for surgery

Joint replacement patients with Croft grade 5 showed a physical functioning score improvement of 19.4 points (95% confidence interval 7.7, 31.2) greater than their counterparts with Croft grade 0 to 3. This suggests that OA patients with more severe X-ray findings should be given higher priority for total hip arthroplasty, the researchers suggest.

BMI was unrelated to change in physical functioning in this cohort. Surgeons may be careful in selecting obese patients for this procedure, but a BMI in the range of up to 30 should not be a deterrent to hip replacement as long as the patient is healthy enough to undergo surgery, the researchers conclude. "We found no indication that patients who are overweight benefit less from total hip arthroplasty, but further evidence is needed on the prognostic influence of more severe obesity."

Patients who were waiting for a hip replacement had markedly worse physical functioning than the controls, but only small differences in vitality and mental health at the start of the study. Mental health improved by a median of 12 points in both the cases and controls, the study showed. "Our findings are consistent with a sustained beneficial impact on physical functioning following total hip arthroplasty for OA, but we found no evidence for parallel improvement in vitality or mental health," the study authors write.

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