Why Patellofemoral Replacement Is a Good Option for Isolated OA
In the abstract from his presentation at ICJR’s Pan Pacific Orthopaedic Congress, Dr. Fred Cushner explains why he prefers this procedure for a patient with isolated osteoarthritis and anterior knee pain.
By Fred D. Cushner, MD
Isolated patellofemoral osteoarthritis occurs in 5% to 10% of patients, and it is more common in female patients than in male patients.
When these patients need surgical treatment, I prefer patellofemoral replacement, sometimes called “the forgotten uni.” Indications for patellafemoral replacement include:
- Isolated disease
- Limited maltracking
- Anterior knee pain
Here are my top 10 reasons for performing patellofemoral replacement.
Benefits of partial knee arthroplasty. Patellofemoral replacement is a bone-conserving option. The analogy has been made numerous times: A dentist does not take out all of your teeth when only 1 is decayed. Similarly, do you change all your vehicle’s tires when only 1 is flat? Perhaps you would if the other tires were in bad condition, but if the other 3 are normal, changing all of them would be considered an aggressive option.
Cruciates are preserved. The debate continues regarding posterior substituting versus cruciate retaining knee designs. Newer designs (variations of old designs) are being introduced that preserved both cruciate ligaments. Improved balancing and better proprioception have been claimed as advantages, but certainly any mid-range instability is avoided when just the patella and trochlea are resurfaced.
Improved placement options. Surgeons now have more technology available to perform a patellofemoral replacement, with improved placement techniques, including reaming systems, custom systems based on preoperative CT scans, robotic assistance, and even custom prosthetic designs. Patellofemoral replacement has come a long way, and the technique is now more reproducible.
Patient satisfaction with total knee arthroplasty (TKA) is not perfect. Studies of TKA have reported good long-term results with excellent longevity, but that is not the complete picture. Postoperative TKA patients frequently report anterior knee pain, which can persist despite a “successful” TKA procedure.
Excellent clinical results noted with patellofemoral replacement. Sisto and Sarin reported 100% of their 25 patients with custom patellofemoral replacements had excellent or good results (18 excellent, 7 good).  Leadbetter et al reported on a literature review of 12 studies and noted disease progression at the tibial-femoral joint was a common form of failure.  Kooijman et al reported excellent long-term results at 17 years with only 2 failures in 56 patients, both noted to be due to arthritis progression. 
It is an easy revision. Let’s face it: This is not a complicated revision. The femoral component is easily removed, with the patella often being maintained. There may be some insignificant anterior bone loss, but standard primary femoral components are usually sufficient at the time of the revision. 
Current procedures have lower complication rates. Historically, with inferior designs and instruments, significant complication rates were noted with patellofemoral replacement. Lonner, however, recently reported a complication rate of 4% with current implant designs, compared with a 17% complication rate with first-generation designs. 
Better indications. Current indications help select the ideal patients. As I mentioned above, this procedure is best for isolated osteoarthritis of the anterior knee compartment. Best results are seen when proper patella alignment and soft tissue balance can be achieved. Mild patella malalignment can be corrected at the time of surgery, but the procedure should be avoided in severe dislocation incidents.
Wear is not an issue. Although progression of osteoarthritis can occur, osteolysis or prosthesis wear has not been reported. Therefore, patellofemoral replacement appears to be a safe and effective procedure, with patients returning to and maintaining an active lifestyle.
It is a fun procedure. Patients do well and appreciate the benefits mentioned above.
Fred D. Cushner, MD, is from the North Short-LIJ Orthopedic Institute, New York, New York.
- Sisto DJ, Sarin VK . Custom patellofemoral arthroplasty of the knee.J Bone Joint Surg Am 2006 Jul;88(7):1475-80.
- Leadbetter WB, Ragland PS, Mont MA . The appropriate use of patellofemoral arthroplasty: an analysis of reported indications, contraindications, and failures. Clin Orthop Relat Res 2005 Jul;(436):91-9.
- Kooijman HJ, Driessen AP ,van Horn JR .Long-term results of patellofemoral arthroplasty. A report of 56 arthroplasties with 17 years of follow-up. J Bone Joint Surg Br 2003 Aug;85(6):836-40.
- van Jonbergen HP, Werkman DM ,van Kampen A. Conversion of patellofemoral arthroplasty to total knee arthroplasty: A matched case-control study of 13 patients. Acta Orthop 2009 Feb;80(1):62-6.
- Lonner JH. Patellofemoral arthroplasty: pros, cons, and design considerations.Clin Orthop Relat Res 2004 Nov;(428):158-65.