Secondary Patellar Resurfacing in TKA: A Combined Analysis of Registry Data and Biomechanical Testing

The German Arthroplasty registry (EPRD) has shown that different prosthesis systems have different rates of secondary patellar resurfacing: four years after implantation, the posterior-stabilized (PS) Vega prosthesis has a 3.2% risk of secondary patellar resurfacing compared to the cruciate-retaining (CR) Columbus prosthesis at 1.0% (both Aesculap AG, Tuttlingen, Germany). We hypothesized that PS implants have increased retropatellar pressure and a decreased retropatellar contact area compared to a CR design, which may lead to an increased likelihood of secondary patellar resurfacing. Eight fresh frozen specimens (cohort 1) were tested with an established knee rig. In addition, a possible influence of the registry-based patient collective (cohort 2) was investigated. No significant differences were found in patient data–cohort 2-(sex, age). A generally lower number of PS system cases is noteworthy. No significant increased patella pressure could be detected with the PS design, but a lower contact area was observed (cohort 1). Lower quadriceps force (100°–130° flexion), increased anterior movement of the tibia (rollback), greater external tilt of the patella, and increasing facet pressure in the Vega PS design indicate a multifactorial cause for a higher rate of secondary resurfacing which was found in the EPRD patient cohort and might be related to the PS’ principle function.

Native Patella Retention Versus Resurfacing in a Cohort of Staged Bilateral Total Knee Patients

Background: Patellar resurfacing in total knee arthroplasty remains a point of controversy within the literature and the generally followed paradigm varies among regions.Methods: In effort to elucidate a difference following the change from universal patellar resurfacing to universal non-resurfacing, 32 patients with bilateral TKA that included one resurfaced and one native patella were retrospectively reviewed at average follow up 21.4 months from the most recent surgery.Results: No difference was observed in patient satisfaction, KOOS-ADL score, and VAS scores. No complications or secondary patellar resurfacing occurred.Conclusions: Therefore, patients perceive no difference between knees with native patella retention or a resurfaced patella in regards to pain and function.

Secondary Patellar Resurfacing after Primary Bicondylar Knee Arthroplasty did Not Meet Patients’ Expectations

Secondary patella resurfacing is a controversial procedure which is applied in patients with anterior knee pain after a bicondylar knee arthroplasty (with unresurfaced patella). A group of 46 patients were submitted to this procedure and their satisfaction, range of motion and pain improvement was evaluated. 52.2% of the patients were satisfied with the procedure, with an improvement in pain (Visual Analogue Scale) of 65% and an improvement in range of motion in 56,5%, with roundabout half of the patients having no resolution to their complaints. Whilst an improvement was not achieved in all patients, as it was initially hypothesised, this procedure should be considered when a revision knee arthroplasty is performed with an unresurfaced patella.