THR Beats Resistance Training for Hip OA Pain, Function

For people with severe symptomatic hip osteoarthritis, total hip replacement (THR) alleviates hip pain and improves function much more effectively than a resistance training program supervised by a physiotherapist, according to the results of a randomized controlled clinical trial. 

In the PROHIP study, the mean increases in Oxford Hip Scores from baseline to 6 months were 15.9 points for THR and 4.5 points for resistance training. The 11.4-point difference in scores was both statistically and clinically significant, the study’s investigators report in the New England Journal of Medicine. 

“Our results are clear: Surgery is superior to exercise in patients who have hip osteoarthritis and indication for surgery, and now we have finally proven that with the highest level of evidence,” corresponding author Thomas Frydendal, PT, PhD, MSc, told Medscape Medical News.

Frydendal, who was involved in the study while working on his PhD at Vejle Hospital in Denmark, the primary center for the trial, is now a postdoctoral researcher at the Department of Clinical Medicine, Aarhus University, and Department of Orthopedic Surgery, Aarhus University Hospital.

“We believe that our findings are pretty robust,” Frydendal added. “I think if someone in the world conducts a trial similar to ours, they will find fairly close or consistent findings, no matter what type of exercise they choose.”

The PROHIP Study

THR is routinely recommended for the management of severe hip osteoarthritis, but since there are no clinical trial data on the effectiveness of this procedure as compared with first-line treatment such as resistance training, the PROHIP study was conceived. 

The trial was conducted at four Danish orthopedic centers and designed as a superiority study, the hypothesis being that THR would be better at alleviating self-reported hip pain and improving hip function than resistance training. 

Of a possible 1474 individuals with a clinical suspicion of hip osteoarthritis, 791 were deemed eligible for inclusion in the trial. Inclusion criteria were being aged 50 years or older and having an indication for THR based on the presence of hip pain and clinical and radiographic findings.

However, the majority (86%) declined to enter the study, with almost half (43%) deciding to have a THR and enroll in a parallel observational cohort. This meant that only 110 (14%) individuals agreed to participate and underwent randomization, which does limit the study’s generalizability, the PROHIP investigators acknowledged. 

Design and Study Population

The change in Oxford Hip Score from baseline to 6 months was selected as the primary outcome measure based on the findings of a prior qualitative study. This 12-item, patient-reported outcome measure gives a score ranging from 0 to 48, with higher scores indicating less hip pain and better hip function. The estimated minimal clinically important difference is a change of 5 points. 

After a baseline assessment, 53 of 109 individuals were randomly assigned to undergo THR and 56 to participate in the resistance training program. Overall, the mean age of participants was 67.6 years, and half were women. The average duration of hip pain was a median of 1.7 years. 

The median time to receipt of the allocated treatment was 2.8 months in the THR group and 0.5 months in the resistance training group. 

Those allocated to the THR group also underwent a “fast track” program that involved patient education, pain management, and early mobilization. 

The resistance training group received 12 weeks of exercise supervised by a physiotherapist and then offered 12 weeks of additional exercise conducted on their own. The physiotherapist-supervised exercise sessions were held twice weekly and lasted for 1 hour. These started with a 10-minute warm-up on a stationary bike, followed by a standard set of resistance-based exercises that included a leg press, hip extension, hip flexion, and hip abduction. 

‘Reassuring’ Results

Commenting for Medscape Medical News, consultant orthopedic surgeon Antony Palmer, MA, BMBCh, DPhil, said: “It’s reassuring that patients with advanced symptomatic osteoarthritis do well with hip replacements.”

THR does of course come with the potential risk for complications, but “the rate of these is what you’d expect for that procedure,” Palmer said, who works for the Nuffield Orthopaedic Centre, Oxford University Hospital NHS Foundation Trust, and is a senior clinical research fellow at Oxford University in England.

In the THR arm, there was one case of prosthetic joint infection, one hip dislocation, two revision surgeries, one instance of foot drop, and one case of gastroesophageal reflux. Meanwhile, in the resistance training group, there was one hip dislocation, one pelvic fracture, one case of atrial fibrillation, and one urinary tract and renal infection. 

Overall, any serious adverse event was reported in six (12%) of 48 patients in the THR arm vs five (9%) of 55 participants in the resistance training group, of which only one, occurring in the resistance training group, resulted in discontinuation of the program. 

Resistance Training Role 

A notable finding was that, at 6 months, five (9%) people assigned to the THR arm had not undergone surgery, and 12 (21%) people in the resistance training group had undergone a THR.

This could suggest two things, Palmer suggested in the interview. The first is that there could be a small proportion of people assigned to THR who may not need the operation and do well with exercise therapy. And, conversely, there may be those who would do well having the surgery without first going through the intermediate stage of physical therapy. 

It’s a suggestion that “maybe we’ve got to refine that a bit better and identify the patients that really do benefit from physiotherapy and who might not need hip replacement as a result,” Palmer said.

Or in other words, “should all patients undergo a program of physiotherapy before considering surgery?” he added.

Authors’ View

The PROHIP investigators conclude: “These results support current recommendations for the management of hip osteoarthritis and may be used to inform and guide shared decision making in clinical practice.”

Moreover, the results “do not oppose the use of resistance training as initial treatment,” says the authors. 

Frydendal highlighted in his interview with Medscape Medical News that nearly three out of four of the patients reported not to have undertaken any type of supervised exercise before entry into the study, which is a first-line, guideline-recommended option.

“If a patient tells me, ‘I haven’t done any exercise previously,’ I’d say, ‘let’s start by completing a 6- to 12-week exercise program that is tailored to your individual needs and evaluate your symptoms afterward,” he said. 

“But we should refer the patient if our first-line treatment does not offer any improvements in the patient’s symptoms, as surgery with total hip replacement is clearly a really good treatment option,” Frydendal said.

The study was funded by the Danish Rheumatism Association, among other independent bodies. Frydendal and Palmer reported no relevant financial relationships. 

Sara Freeman is a freelance medical journalist based in London, England.