Going back and forth between his office and the deputy clerk’s office isn’t such a big deal anymore for Mike Rowlison.
The 61-year-old clerk-treasurer of the town of LaGrange used to limit his walking, especially taking the stairs, because of the pain it caused. His knee problems started when he was in his early 50s, but he found relief last month in the form of a partial knee implant.
As the name implies, the surgery involved only part of Rowlison’s knee – the inner, or medial, component targeted in most partial knee procedures. Rowlison says he feels great and will probably to have the same operation – which was done on his left knee – performed on the right one in October. As more people undergo knee replacement operations, many with isolated damage are getting partial knee implants. The surgery is used when a complete overhaul isn’t needed and promises quicker recovery, less pain and less bone loss than a total knee replacement.
Partial knee implants have been around for decades, but technological advances and the introduction of improved implants in the U.S. market have renewed enthusiasm for the option. Those advances and long-term study results have tested traditional thinking about the partial implant’s place as a short-term or late-in-life fix. Many surgeons consider it a long-lasting option for patients of all ages.
Surgeons vary in their use of partial implants and characterizations of whom could benefit. The American Academy of Orthopaedic Surgeons estimates 6 percent to 8 percent of patients with arthritic knees are good candidates for the surgery. But many surgeons – including some academy members who presented at the 75th annual academy meeting this month in San Francisco – think the number is considerably higher, one-third or more. That reflects more aggressive use of partial knee implants outside the U.S.
Dr. Steven Fisher of Fort Wayne Orthopaedics operated on Rowlison in February. Fisher implants the Oxford partial knee system made by Warsaw-based Biomet Inc. in about half of all his surgical patients. He’s bullish about the implant, owing to his personal experience and studies showing its long-term effectiveness.
The system was first implanted more than 25 years ago but didn’t gain approval in the U.S. until about four years ago. The most commonly used partial knee implant is also the only fully mobile-bearing partial knee system in the U.S., according to the company. The implant uses a moveable plastic bearing to give patients greater range of motion.
Numerous studies show success rates easily exceeding 90 percent after 10 and 15 years, drawing comparisons to full knee replacements. Surgeons say it’s more technically demanding to implant – requiring special training – compared with fixed-bearing partial knee systems that tend to perform slightly better in the short term. But company officials say its long-term prowess is the reason it’s leading the partial knee market.
Fisher, who has special training to implant the Oxford, thinks opportunities in the partial knee market go far beyond what’s currently realized. An estimated 49,400 partial knee implant procedures were performed in the U.S. in 2006, less than 10 percent of all primary knee implant surgeries, according to the latest figures from Orthopedic Network News, an industry newsletter.
The market shows that most American surgeons are generally conservative in their use of partial knee implants, despite the successes of their colleagues who use the technology more liberally.
Dr. Michael Lee of Fort Wayne-based Orthopaedics Northeast says about 10 percent of the knee surgeries he performs are partial knee implants. Like Fisher, he uses the Oxford and acknowledges the proportion of patients considered candidates for partial knee implants varies greatly by surgeon, depending on that surgeon’s philosophy, training and other factors.
Overall, success with partial knee implants is highly dependent on proper patient selection, Lee said. He considers the surgery for patients with arthritis fairly isolated in the medial compartment of their knee, but he doesn’t follow all traditional criteria.
The American Academy of Orthopaedic Surgeons says a partial knee replacement “is best suited for the older, slim person with a relatively sedentary lifestyle.” But Lee and others in the field aren’t opposed to partial knee implants for demographics including younger patients. With a partial implant, the patient retains more bone and might be able to delay or avoid full knee replacement, he said.
“It feels more like a normal knee to patients” because much of the “native knee” is still intact, Lee said.
But conserving bone isn’t limited to knee implants.
“Overall, with joint replacement, bone conservation is where the market is going,” said Scott Ellison, a large-joints analyst with PearlDiver Technologies Inc., a Fort Wayne-based orthopedic data firm. “It fits right in with the trend we’re seeing with hips.”
First approved for the U.S. market in 2006, hip resurfacing technology provides some patients an alternative to total hip replacement. With hip resurfacing, only the surface of the hip ball, or femoral head, is removed; it’s then capped by smooth metal.
Warsaw’s Orthopedic Big Three – Biomet, Zimmer Holdings Inc. and DePuy Orthopaedics Inc. – are working to get FDA approval to market hip resurfacing technologies. DePuy got pre-market approval in September, one of the first steps in the regulatory approval process. Company officials declined to speculate when it might get final FDA approval, but at least one competitor thought DePuy would be the first of the Big Three to bring its hip resurfacing technology to market.
Meanwhile, local advances continue to be made in partial knee technology.
A new partial knee system developed by a Warsaw-based startup is expected to be out the third quarter of this year. It’s the only partial knee implant FDA-approved for use with arthroscopic surgery (which employs a tiny camera to show the inside of a joint on a TV monitor), according to Dr. Ron Clark, founder and chairman of VOT Arthroscopic Solutions.
The South Bend-based surgeon developed the Solo partial knee system, which requires a 1-inch incision to be implanted. Traditional partial knee replacement surgery requires a 3- to 5-inch incision.
Clark expects good things for Solo and the partial knee implant market in general. Successes in the sector are driving a growing market, he said.