A Border Collie Ran Flyball Again 10 Months After a Hip Replacement. Cats and Toy Breeds Are Next in Line

The smallest patients have long been offered a salvage procedure and told it was good enough. Cementless implants in micro sizes change that conversation, and the reason why is worth understanding precisely.

A video showed up unannounced in Dr. David Knazovicky's inbox. A border collie named The Tick, running the fourth leg of a flyball relay, sprinting 51 feet down a course, clearing hurdles, grabbing a tennis ball and coming back over the hurdles again.

Knazovicky, a small animal orthopedic surgeon at the NC State College of Veterinary Medicine, had replaced that dog's hip less than a year earlier. His own description of what these cases look like afterward is understated. The dogs are weight bearing the next day, still sore from the procedure itself, and later on it becomes clear the surgery “really takes the pain away.”

Surgeons rarely see this. Most patients come back for a three month recheck and then vanish into the rest of their lives, which is what success looks like and also why it goes unwitnessed.

The news attached to that video is that NC State is preparing to offer the same procedure to patients who have mostly been excluded from it.

What is actually new, stated precisely

This distinction matters, and it is easy to get wrong in a headline.

Total hip replacement in very small dogs and cats is not brand new. Micro and nano sized implant systems have existed for roughly two decades, and thousands of these procedures have been performed in patients in the range of about four to twenty pounds. There is published literature on outcomes in both dogs and cats.

What has changed is the fixation. Those small implants have historically relied on bone cement. What is now reaching the micro and toy sizes are press fit, cementless components, the same approach that has been standard in larger dogs for years. That is the advance, and it is the one worth explaining to clients rather than the broader claim that small patients can suddenly get hips.

Why cement is the part everyone is trying to get away from

Cemented technique means preparing a bed in the bone, filling it with cement, and setting the implant while the cement hardens. It works, and it has worked for decades.

The weakness is the interface. Cement sits between metal and bone, and over enough years that junction can loosen. In an older patient, loosening may never become clinically relevant. In a young athletic dog with a decade of use ahead, it can.

Cementless implants take the opposite approach. The surface is porous, and bone grows into it, so the implant becomes continuous with the patient's own skeleton rather than glued to it. The fixation gets stronger over time instead of gradually failing.

This is not a new insight, and NC State's involvement in it is a large part of why the technology exists at all. The work traces back to the early 1990s, when a surgeon developing a cementless design for human hips collaborated with Dr. David DeYoung at NC State to produce a porous coated system for dogs. A trial at NC State succeeded, a longer clinical study followed, and the results held.

Then the company shrank its research division and stopped making the implants, and a procedure that worked simply stopped being available.

For roughly five years, surgeons who had proved the cementless approach went back to cemented hips because there was nothing else to use. Biomedtrix reintroduced an uncemented system in 2003 with substantial input from the same NC State group, and in 2022 the American College of Veterinary Surgeons Foundation gave DeYoung its Legends Award for the work.

It is a useful reminder that clinical availability in this profession does not track evidence alone. A technique can be validated, published and abandoned because the market for the hardware is too small.

What the alternative has been, and its honest limits

Cats and small dogs with debilitating hip pain have been offered a femoral head ostectomy, usually called an FHO, in which the femoral head is removed and surrounding soft tissue forms a false joint that holds the limb in position.

FHO is a good operation and it does something valuable. It removes the painful bone on bone contact. In small patients it is tolerated well, in part because a small animal can redistribute load across the other limbs more easily than a large one.

Dr. Simon Roe, the retired NC State orthopedic surgeon who helped build this field and who has been mentoring Knazovicky, is direct about the trade off. Small non athletic patients tolerate an FHO, and their gait is still not normal.

That sentence is the whole clinical argument for extending hip replacement downward. FHO is a salvage procedure. It converts a painful joint into a functional non joint. Replacement restores the joint. For a nine pound dog whose owner mainly needs him comfortable on a couch, salvage may be exactly right. For a working cat of a household that hikes, or a toy breed with years of activity ahead, the difference between a normal gait and a compensated one stops being academic.

How the decision actually gets made

Knazovicky frames it as a conversation about expectation rather than a protocol, and the framing is worth borrowing.

Medical management of hip dysplasia is genuinely effective for many patients. Weight control, pain management and physical therapy carry some dogs comfortably for a decade without surgery. Most of the uncemented hip replacements done at NC State have been in young animals with congenital hip disease or in canine athletes with years of performance ahead of them.

What decides it is how much mobility a family believes their animal needs in order to have a good life, which is a values question dressed as a clinical one and should be handled as such.

Owners should also understand what they are signing up for after surgery. The first month is strictly restricted activity, with a graded return over the following two, and most patients are close to running again at three months. The owner who brought The Tick back to flyball invested in intensive private rehabilitation to get him there. Outcomes like that are not only surgical.

The part students and residents should notice

There is a career story running underneath the clinical one.

Knazovicky is completing a fellowship in Joint Replacement Surgery, a training pathway the American College of Veterinary Surgeons approved roughly seven years ago. Only about ten institutions are approved to deliver it, and only a handful of surgeons are currently in it. Roe is a founding fellow of that program. DeYoung mentored Roe. Roe now mentors Knazovicky. Access to the newest small implants runs through structured mentorship and workshop training rather than a purchase order.

That is how a technical subspecialty actually reproduces itself, and it is worth seeing clearly if you are trying to plan a career. The bottleneck in advanced surgery is rarely information. It is supervised repetition inside a lineage of people who already do the thing, and there are only so many of those seats.

Knazovicky did not arrive planning any of this. He came to NC State in 2012 expecting a career as a pain researcher.

What comes after hips

Dr. Anthony Blikslager, associate dean and director of Veterinary Medical Services at NC State, has pointed to the obvious next question, noting that Knazovicky is beginning to assess other joints, including the stifle and elbow, for replacement.

Hip replacement in dogs is the mature end of veterinary joint replacement, with decades of implants, revisions and outcome data behind it. Stifle and elbow replacement are considerably harder problems, mechanically and biologically. But hips looked impossible once too, and the pathway from there to here ran through exactly this kind of institution, doing exactly this kind of unglamorous long term follow up.

Which brings it back to a border collie clearing hurdles ten months after surgery. That is what the endpoint of thirty years of implant development looks like in practice, and the surgeon only knows about it because an owner thought to send the video.