FHO vs total hip replacement: separating fact from fiction

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At VMX 2023 in Orlando, Florida, Terri Schiller, DVM, CCRT, DACVS, presented on the surgical outcome of a femoral head ostectomy (FHO).¹ She challenged the notion that the procedure always offers an acceptable result, when a total hip replacement (THR) is the gold standard of treatment in humans with hip disease, suggesting THR should be part of the conversation for pets, too.

Hip disease is very common among companion animal veterinary patients. Veterinarian practices have spent an enormous amount of time talking about hip and knee issues. The end goal of hip surgery is to eliminate pain and restore function. So, when you’re thinking of what surgical procedure to prescribe for your patient—be it an 80-Ib dog or a 12-Ib cat—ask yourself, “Can I alleviate pain and restore function?”

In most cases, we think of an FHO or a THR. And although FHO is more affordable, the literature supports it’s likely not the best option, says Schiller.

FHO

Schiller said the thought process around hip disease is often: The bones are rubbing against each other; let's make that go away. We'll take the femoral head away, eliminate the bone-to-bone contact, and make it less painful. It's a good theory, right? The problem is this procedure doesn’t actually translate these results, Schiller said. If fact, in humans, this procedure is no longer done unless there are extenuating circumstances because it doesn't eliminate pain or restore function. Approximately 45% of patients who have this procedure are not independently mobile, Schiller added.

What’s remarkable is even though this procedure has been around for 75 years, there's not a lot of scientific literature on the outcomes of an FHO. Much of the literature is decades old and is largely subjective, based on clients’ assessments of how their animal is walking, running, etc.

A study from 1977 looked at objective data in 267 cases. They followed many of the cases for almost eight years and found that 50% of the dogs and cats had muscle atrophy, 70% had limb shortening, and 75% had restricted range of motion on their hip joint.² Functionally, the clients thought they were doing fine, but when they looked at objective measurements of limb function, the results were not great. Other studies show similar results. The common themes among the literature are persistent muscle atrophy in 50-80% of cases, limb shortening in 60-85% of cases, decreased hip extension in 75% of cases, less static weight bearing, and gait abnormalities in 30-60% of cases.^2-4

What’s more is when they look at weight, there is little to no difference in the outcomes between an 80-Ib pet or a 3-Ib pet that underwent an FHO procedure—it is a biomechanical problem with the procedure, Schiller said.^2-4

Hip replacement

Advances in companion animal hip replacement have been dramatic over the past 25 to 30 years. In fact, most THR cases have a straightforward surgery, unremarkable recovery, and return to a normal level of exercise and function, Schiller said. You can say to your client with a straight and honest face, “If the surgery goes well, this implant should last the lifetime of your pet, allow them to return to an active and normal lifestyle, and eliminate pain.” Of course, there could be complications because it's an advanced orthopedic procedure, but we do what we can do to minimize complications, and generally, the complications are fixable when they develop.

Literature on THR is extensive. Only looking at the last 30 years, there are more than 330 manuscripts devoted to THR in dogs and cats, Schiller said. And most of the research, according to Schiller, says that 90% of THR procedures will have a successful outcome. Some studies show objectively with force plate data that at 3 months postoperatively, patients are back to normal weight bearing.¹

The takeaway

THR is the gold standard treatment for humans with hip disease, and this is true for companion animals, too.

“I'm not naive enough to think that every dog or cat with a bad hip is going to get a hip replacement,” Schiller said. “But I'm going to have an honest conversation with the client, and instead of making it about, ‘Well, it's cheaper to do an FHO than a THR,’ because that's true, I am going to have the functional discussion. ‘We can do an FHO; it might work out OK. But the literature says it probably won't.’ The majority of patients won’t have restoration of function and pain-free mobility. I can give you that with a joint replacement. It is more expensive, but let's figure out how we can make that affordable to you.’”

References

1. Schiller T. Beyond the FHO: myths and truths. Presented at: Veterinary Meeting and Expo. January 14-18, 2023; Orlando, FL.
2. Duff R, Campbell JR. Long term results of excision arthroplasty of the canine hip. Vet Rec. 1977;101(10):181-184. doi:10.1136/vr.101.10.181
3. Off W, Matis U. Excision arthroplasty of the hip joint in dogs and cats. Clinical, radiographic, and gait analysis findings from the Department of Surgery, Veterinary Faculty of the Ludwig-Maximilians-University of Munich, Germany. 1997. Vet Comp Orthop Traumatol. 2010;23(5):297-305.
4. Engstig M, Vesterinen S, Morelius M, Junnila J, Hyytiäinen HK. Effect of Femoral Head and Neck Osteotomy on Canines' Functional Pelvic Position and Locomotion. Animals (Basel). 2022;12(13):1631. Published 2022 Jun 24. doi:10.3390/ani12131631