Patient-Specific Custom Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) can be done with a number of devices that implement both inlay and onlay designs. Recent innovations in custom instrumentation allow for a new class of PFA that can precisely match the variable trochlear morphology.

Patients with severe patellofemoral arthritis and preserved tibiofemoral joint space who had conservative treatment that has failed may benefit from PFA.

A medial parapatellar arthrotomy of roughly 10 cm is used to evert the patella for visualization of the patellofemoral cartilaginous surfaces. An oscillating saw cut is performed while carefully preserving at least 12 mm of patellar bone. Three drill holes are made for future implantation of the patellar surface. Next, attention is turned to the trochlea, where any remaining cartilage is removed with a curette, with care taken not to remove any subchondral bone. A custom drill guide is then placed on the trochlea for 3 drill holes, followed by auxiliary holes with a drill bit for cement interdigitation. The wound is copiously irrigated and dried before cement is applied to the trochlea. The custom trochlear implant is carefully malleted in place, and excess cement is removed around the edges. Cement is then applied to the patella before similar implantation of the patellar implant. The medial parapatellar arthrotomy is then closed and a lateral lengthening is performed. Full range of motion is checked for appropriate patellar tracking.

Implant survivorship is greater than 90% at 5 years and 83% at 10 years. With respect to patient-reported outcomes, Knee Society functional score improved from 49 to 89, and Knee Society objective score improved from 52 to 89. In a second study featuring 25 patients with a mean greater than 11 years of follow-up, no revisions were seen, with over 90% of patients able to return to sport.

Utilizing the patient's native anatomy with a new, custom groove allows for improved, nonpathologic patellar tracking, especially in dysplastic cases, as seen in this case. This method for PFA holds the potential for improved patient satisfaction and advancement of patient-specific care in arthroplasty.

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.