One in Five Hip Replacement Patients Gets New Back Pain

"The hip is perfect. It's my back now."

I hear that sentence a lot, usually somewhere between four months and a year after surgery, and it always comes with a little embarrassment attached. Like the person is complaining about a gift.

A woman said it to me in July and then immediately apologized for bringing it up. She had waited five months to mention it to anybody, because the surgery had worked and she did not want to seem ungrateful. Five months.

The surgery did work. The groin pain that used to wake her at two in the morning was gone. She could put a sock on. And now there was a dull, nagging ache across the low back that was not there before, and when she mentioned it at the follow-up visit, the answer was some version of "well, you are getting older."

That answer bothers me, because somebody actually went and counted this.

Somebody counted

A group at the Rothman Institute in Philadelphia followed 344 patients through hip replacement and published the results in Clinical Orthopaedics and Related Research in 2010. They asked about low back pain before surgery and then tracked what happened after.

The number most people quote from that study is the good one. Of the 170 patients who had low back pain going in, it resolved in 113 of them, about two thirds, after the hip was replaced.

The number nobody quotes is the other one. Of the 174 patients who had no back pain at all before surgery, 35 developed it within a year. Right around one in five.

That is not a rounding error and it is not a coincidence. If you are one of those thirty-five, you are not unlucky and you are not imagining it. You are a documented outcome.

Why a new hip changes your back

The study counted what happened. It did not prove the mechanism. But the reasoning holds up and it matches what I see on the table.

Consider what your spine had been doing for the two or three years before your surgery.

A stiff arthritic hip cannot extend. So every step you took, your pelvis tipped and your low back arched a little extra to let that leg get behind you. Your spine had been quietly covering for the hip, thousands of times a day, long enough that the pattern stopped feeling like a pattern and started feeling like just how you walk.

Then a surgeon gives you back thirty degrees of motion overnight.

Your hip now moves. Your spine has no idea. The muscles that had been holding you in that old compensated position are still short in some places and long in others, still firing on the old timing, and now they are doing all of that on top of a joint that is suddenly behaving differently. Your pelvis sits at a different angle. Your leg may be a slightly different length than it was, which surgeons work hard to avoid but cannot always deliver to the millimeter.

Add the weeks of sitting, the limited walking, the abdominal and hip muscles that got weaker during recovery, and the low back is asked to be the stable one while everything around it has been rearranged.

The hip got fixed. The habits did not.

Why nobody connected it for you

Partly because of how care is divided up.

The surgeon's job was the hip and the hip is a success. Your post-op therapy, if you got any beyond a few weeks, was aimed at getting you walking safely and getting the hip range back. Nobody was assigned the spine.

And partly because of timing. New back pain often shows up at four to eight months, well after the surgical follow-ups have ended. By then it looks like a fresh, unrelated problem, so it gets treated as one. Which means imaging of the lumbar spine, which finds degenerative changes, because a lumbar MRI on anyone over sixty always finds something.

Now you have a diagnosis that describes your spine accurately and explains your pain badly.

What to do about it

If this is you, the good news is that most of what is driving it is mechanical, and mechanical things respond to being asked to do something different. Tissue takes its instructions from what you load it with. That cuts both ways, which is why this is fixable.

• Get your hip extension measured on both sides. If the new hip still cannot get the leg behind you, the compensation never stopped and the surgery did not resolve it. This is common and it is fixable with mobility and gait work.
• Get somebody to watch you walk. Really watch. Most people come out of hip replacement with a leftover limp they cannot feel anymore, and every step of that limp is a small demand on the spine.
• Rebuild the glutes on the surgical side. Hip abductor weakness after replacement is well documented in the research and it lingers longer than most people expect. A weak side hip means the pelvis drops on every step, and the low back absorbs that drop.
• Ask about leg length. If one leg feels longer, say so out loud at your next appointment. It is measurable, and where it matters, it is often manageable with something simple.

And know the lines that need a doctor rather than a therapist. Numbness or tingling down the leg, weakness in the foot, any change in bowel or bladder control, fever with back pain, or pain that is worse at rest and at night than it is when you move. Those are physician visits, not exercise problems. Same for new calf swelling, warmth, or tenderness at any point after surgery, which needs to be checked promptly.

The bottom line

You were told the hip was the problem. The hip was a problem. It was also the thing your spine had organized itself around for years, and when it changed, your spine got handed a new job with no notice and no training.

One in five people in that study went through the same thing. Almost none of them were told to expect it.

So here is the question I would ask you if you were sitting across from me. How long have you been telling yourself this is just what your back does now?

There is no wrong answer to that and no lecture attached to it. But if your hip is fine and your back is not, that is worth a real look at how the whole leg and pelvis are moving today, rather than a shrug about your age.

Had your hip replaced and ended up with a back that hurts? Come let us look at the whole chain, not just the spot. The first visit is a free 20-minute movement assessment, in clinic. No charge, no insurance, no obligation to book anything after, and no hard sell if you decide to keep managing it yourself. Call the West Front St office at (231) 944-6541, or the Munson Ave office at (231) 421-9300.

If you want it, my book on hip replacement recovery is free at thesuperiortherapy.com.