CATEGORY: MOBILITY, BONES & JOINTS
Adults with hip osteoarthritis severe enough to qualify for surgery improved far more with a new hip than with a supervised strength-training program in a randomized trial published in the New England Journal of Medicine.1 Six months after treatment began, patients assigned to hip replacement had gained an average of 15.9 points on a standard 48-point score of hip pain and daily function, while those assigned to exercise had gained 4.5 points on the same scale.
Routine in the Operating Room, Untested in a Trial—Until Now
Hip replacement—surgery that removes the damaged ball-and-socket joint and replaces it with an artificial one—is one of the most common operations in medicine, routinely recommended when osteoarthritis, the wear-related breakdown of a joint’s cushioning cartilage, becomes severe. Yet as the study’s authors note, no randomized trial had ever directly compared the operation against a nonsurgical alternative such as exercise. The PROHIP trial, run across Danish hospitals, was designed to close exactly that gap: it enrolled 109 patients aged 50 or older (average age 68) whose hip osteoarthritis was severe enough that surgery was already indicated, and assigned each by chance—the design that makes the two groups alike in everything except the treatment being tested—to either a hip replacement or a program of progressive resistance training.
Socks, Stairs, and a Forty-Eight-Point Ladder
Both groups were measured with the Oxford Hip Score, a questionnaire that asks about the realities of living with a bad hip—how much it hurts, and whether you can put on your own socks, climb stairs, or get in and out of a car. Scores run from 0 to 48, with higher numbers meaning less pain and better function, so the scale works like a 48-rung ladder. Over six months, the surgery group climbed about 16 rungs on average; the group doing resistance training—strength exercises for the hip and leg muscles, such as squats and step-ups, performed under supervision with the effort gradually increased as strength builds—climbed about 4½. The gap between the groups was 11.4 points (95% confidence interval, 8.9 to 14.0), a difference the trial’s authors describe as clinically important—large enough to be felt in daily life, not just seen in the statistics.
One in Five Exercisers Chose Surgery Within Six Months
The trial’s crossovers tell their own story. By the six-month mark, 12 of the 56 patients assigned to exercise (21%) had gone ahead and had their hip replaced, while 5 of the 53 assigned to surgery (9%) had not yet had the operation. Serious adverse events occurred at a similar rate in the two groups; because some patients originally assigned to exercise had already crossed over to surgery by six months, their adverse-event counts included the same kinds of surgical complications seen in the surgery group—a reminder that the operation’s clear benefits arrive alongside real surgical risks. The trial followed patients for six months after treatment began, so it speaks to the first half-year, not to how the two paths compare years later.
What the Smaller Gain Still Says About Exercise
The exercise group did improve—modestly—and four out of five of its members had not moved to surgery by six months. That matters because treatment guidelines generally position exercise as the first thing to try in hip osteoarthritis, with surgery reserved for those whose symptoms persist. This trial does not overturn that sequence; everyone in it had already reached the point where surgery was indicated. What it establishes, with randomized evidence where none existed, is the size of the difference patients at that stage can expect between the two paths: for severe disease, the operation delivered a far larger improvement than a structured strength program did.
Key Takeaways
- In the first randomized trial of its kind, hip replacement improved pain and daily function by an average of 15.9 points on a 48-point score at six months, versus 4.5 points with supervised resistance training, in patients whose hip osteoarthritis was already severe enough for surgery.
- One in five patients assigned to exercise crossed over to surgery within six months, while the exercise-only majority saw modest gains.
- Serious adverse events were similarly common in both groups; since some patients originally assigned to exercise had crossed over to surgery by six months, their adverse-event totals included the same surgery-related complications seen in the surgery group.
- The trial covered patients who already qualified for surgery and followed them for six months, so it does not measure how the two options compare in milder disease or over the long term.
References
- Frydendal T, Christensen R, Mechlenburg I, et al. Total Hip Replacement or Resistance Training for Severe Hip Osteoarthritis. N Engl J Med. 2024;391(17):1610–1620. link