Hip replacement is an effective treatment for osteoarthritis, says a study that followed patients for an average of eight years after surgery.
Previous studies have warned against this surgery stating that it is not beneficial. But, the new research says that they only followed patients for a period of one-year.
The study, led by Professor Cyrus Cooper and Ms. Janet Cushnaghan of the University of Southampton in Southampton, UK, reviewed 282 patients who had OA and were placed on the waiting list for a hip replacement between 1993 and 1995.
The study also included 295 matched controls from the general population.
At the beginning of the study, patients were interviewed about hip injury, pain, physical function, vitality and mental health.
In addition, their BMI was calculated, their hands were examined for Heberden's nodes, an indication of OA, and their hip X-rays were evaluated for severity of OA.
Between 2001 and 2004, the patients completed a self-administered questionnaire asking if and when they had undergone hip replacement, as well as questions about their physical function, vitality and mental health.
Follow-up of the patients took place an average of eight years following hip replacement.
The analysis of the study revealed that 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.
By the time of the follow-up, the physical functioning of the OA patients had improved, while that of the controls had deteriorated, but their vitality had deteriorated.
In addition, better physical functioning at the start of the study was associated with a greater decline at follow-up, but higher BMI seemed to have no impact.
Those with more severe OA according to their X-rays showed the most improvement in physical functioning.
"Our findings are consistent with a sustained beneficial impact on physical functioning following THA for OA, but we found no evidence for parallel improvement in vitality or mental health," Cooper said.
The researchers contemplated that the study was limited because it was an observational investigation as opposed to a randomised controlled trial and information about the patients' disease and surgical procedures was limited.
However, this weakness was offset by the fact that the study had a long follow-up interval and a relatively large number of patients and 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 said.
They suggested that the benefits of hip replacement were substantial and long lasting.
The scientists concluded that the study adds to the accumulating evidence of the long-term benefits of hip replacement, especially in patients with more severe changes seen on X-rays, and that perhaps these patients should be given higher priority for the procedure.
The study is published in the December issue of Arthritis Care & Research.