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Middle-aged patients are seen as optimal candidates for patellofemoral arthroplasty
New prostheses designs may eliminate some of the common problems with the procedure.
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Surgeons continue to battle a high incidence of patellofemoral arthritis and, according to one surgeon, this highlights the need for a reliable patellofemoral arthroplasty technique.
With newer designs such a technique may be achievable, Paul A. Lotke, MD, said at the Current Concepts in Joint Replacement Winter 2006 meeting.
“The newer designs, to date, are yielding results of good to excellent, averaging 75% to 85%, in well-selected patients,” Lotke said.
He discussed the developments being made with these new designs and cleared up some questions on patient selection and indications for this procedure.
Middle-aged patients ideal
Lotke said at present the best candidates for patellofemoral arthroplasty are middle-aged patients, because surgeons can perform a total knee arthroplasty if necessary, unlike in younger patients.
“The elderly with isolated patellofemoral arthritis do well with a total knee, and that’s described in the literature,” Lotke said. “In the young with patellofemoral arthritis or chondromalacia, there’s minimal long-term data available, so the bailout for those young people is relatively limited.”
Lotke said he generally performs the patellofemoral arthroplasty procedure in patients with isolated patellofemoral arthritis. More recently, he has also performed patellofemoral arthroplasty in patients after finding that they have patellofemoral arthritis during unicompartmental arthroplasty.
Patients typically have an osteoarthritic, isolated patellofemoral joint with eburnated bone on the condyle. Further, “We avoid inflammatory arthritis or crystalline deposition disease, severe maltracking [and femoral-tibial arthritis] and high-activity patients,” Lotke said.
Surgeons have come a long way since introducing the first patellofemoral arthroplasty technique in the 1970s, which involved placing a metal cap over the patella. This technique provided pain relief for the patient, but the femoral condyle eventually eroded and the arthroplasty failed, Lotke said.
Now Lotke’s surgical technique begins with a transverse osteotomy across the trochlear groove, parallel to the transepicondylar axis. He then removes the cartilage surfaces and replaces the patella with a dome-shaped component.
“We try to reproduce the patellar thickness. We assess the patellar tracking, and if necessary, do a lateral release to make sure that tracking is absolutely perfect,” Lotke said.
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Images: Lotke PA |
Better clinical reporting
In the past, clinical results for patellofemoral joint arthroplasty were difficult to interpret, Lotke said, mainly due to inconsistent indications and outcomes.
But over the last 2 decades, the literature has improved. Now, results typically average anywhere from 75% to 85% good to excellent, with results varying from 53% to 99%, although “the series [in the literature] are relatively small … so it’s hard to make generalizations,” Lotke said.
Other treatment alternatives for patellofemoral arthritis – including patellectomy, tibial tuberal unloading osteotomy, microfracture, and mosaicplasty – have only shown good to excellent results in roughly 66% of patients, Lotke said.
Prostheses developments
The potential for improving the prostheses designs for patellofemoral arthroplasty is high, Lotke said. Already, new second-generation designs are resolving some common problems in patellofemoral arthroplasty patients, such as catching, crepitus and anterior pain.
“However two problems remain … and are slowly getting solved: patellar instability and cartilage contact in flexion,” Lotke said.
Patellar instability is related to the undercorrected malalignment and soft tissue imbalance, Lotke said.
“Component malposition is also an important problem, which has to be addressed, and there have been some design flaws, which have been corrected in the past,” Lotke said. “The trochlear capture and the J curvatures have been improved, and I’d say that instability has become less of a problem than it was with the original-generation knees.”
These new designs have included features like dome patellas, wider areas for capturing the patella in the trochlear groove and a radius arc that closely resembles the patellofemoral groove.
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For more information:
- Lotke PA. Patellofemoral replacement: The third compartment. #68. Presented at the 23rd Annual Current Concepts in Joint Replacement Winter 2006 Meeting. Dec. 13-16, 2006. Orlando, Fla.
- Paul A. Lotke, MD, professor of orthopedic surgery, University of Pennsylvania, Delaware County Memorial Hospital, 510 Darby Road, Havertown, PA 19083; 610-449-0970; paul.lotke@uphs.upenn.edu. He has indicated that he is a consultant for DePuy and Stryker.