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Award-winning study finds that specific surgical factors, prior surgery increases patellar crepitus risk
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NEW ORLEANS — Patients implanted with a posterior cruciate-substituting prosthesis or those with a short patellar tendon preoperatively are at an increased risk of developing patellar crepitus after total knee arthroplasty, according to findings from a multicenter database study.
“Those who had one or more previous surgeries had an incidence of 63% vs. 30% in the control group” for patellar crepitus, Douglas A. Dennis, MD, said.
Dennis presented the results at the Knee Society Specialty Day Meeting held here. He and his colleagues received the Knee Society 2010 John Insall Award for their analysis of factors related to patellar crepitus based on information from more than 4,000 total knee arthroplasties (TKAs) that were performed between 2002 and 2008, and recorded in the databases of two institutions.
Control-matched evaluation
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Dennis noted that the incidence of patellar crepitus after TKA has been reported to be as high as 14% in the literature. For their study, the investigators analyzed several clinical, surgical and radiographic factors associated with the development of patellar crepitus in what Dennis said “is the largest and only control-matched report analyzing this problem.”
Among TKAs they studied, 60 patients developed peripatellar crepitus that required operative treatment. This occurred within a mean of 10.9 months after surgery, Dennis noted.
Investigators then compared the clinical, surgical and radiographic factors in the operative group to a matched-control group who received a femoral implant of the same design, but did not develop crepitus.
Patellar component factors
Other than the increased incidence of previous knee surgery, “we observed no other differences in any of our clinical data parameters,” Dennis said.
Looking at surgical differences, the investigators found that patients with a smaller and thinner patellar component had an increased risk of developing this complication with 63% of the patients who received the two smallest patellar implants developing crepitus vs. 33% of controls. However, the investigators found that other surgical factors, such as the size of femoral or tibial component, thickness of tibial polyethylene, patellar component shape, bearing style and use of lateral release were unrelated to the incidence of patellar crepitus.
“A reduced patellar tendon length, either preoperatively or postoperatively, increased the risk of developing this condition,” Dennis said.
Additional risk factors revealed by the multivariate analysis included a femoral size less than 3 mm, bearing thickness greater than 12.5 mm and flexion of the femoral component.
Dennis recommended alerting patients who had previous knee surgery or those with reduced patellar tendon length of their risk for developing this condition after TKA. Using a larger-size patellar component when possible may help mitigate the problem, he added.
- Reference:
Dennis DA, Kim RH, Johnson DR, et al. Control-matched evaluation of patellar crepitus after total knee arthroplasty. Presented at the Knee Society Specialty Day Meeting. March 13, 2010. New Orleans.
