Abstract
Whether or not to resurface the patella in total knee arthroplasty (TKA) remains controversial. Several methods of dealing with the patella exist: ALWAYS resurface; NEVER resurface; SOMETIMES resurface. There is good reason to consider selective patellar resurfacing.
First, in an age of partial knee arthroplasty we have become more tuned in to analyzing patterns of arthritis. In TKA there is a high percentage of patients who do not have significant patellar cartilage wear or anterolateral knee pain. These patients may be candidates for leaving the patella unresurfaced in TKA. Arno et al found that 42% of patients had no significant patellar arthritis at the time of TKA. Roberts et al found that only 15% of patients should undergo patella resurfacing based on the presence of exposed bone on the patella; the other 85% could be considered suitable for leaving the patella unresurfaced. Second, despite a cumulative incidence of less than 5–10%, problems related to patellar resurfacing account for perhaps the most catastrophic complications encountered, with treatments that have limited success. These complications include fracture, avascular necrosis, extensor mechanism disruption, and anterior knee pain. Third, it is a fallacy to think that anterior knee pain (AKP) does not exist despite primary patellar resurfacing in TKA. Meftah (Ranawat) et al found that AKP persists in 30% of patients and new AKP develops in 10% of patients after TKA with patellar resurfacing. Barrack et al found that with patellar resurfacing the incidence of AKP is 28% in patients without preop AKP and 9% in those with preop AKP. They also found that without patellar resurfacing the incidence of new AKP was 14% and persistent AKP was 23%. Fourth, only roughly 44–64% of patients who undergo secondary patellar resurfacing for AKP after TKA with an unresurfaced patella actually get relief of their pain, suggesting that there is some other etiology of anterior knee pain. Residual component malalignment, boxy femoral components, PF overstuffing, referred pain or asymmetric resurfacing may explain ongoing pain. Finally, the data in well-designed studies show that selective patellar resurfacing can produce similar outcomes with and without resurfacing, particularly in those without significant patellar arthritis. In multiple studies, higher rates of secondary surgery occur when the patella is left unresurfaced in primary TKA, but this is for “pain” without clear etiology.
On the other hand secondary surgery is rarely performed in TKA with patellar resurfacing for “pain” only, despite its high incidence. The quality of patellar cartilage at the time of primary TKA should be considered, as that may be the best indicator of whether a knee will do well without patellar resurfacing (that is, selective patellar resurfacing may be a better idea than never resurfacing the patella).
While patellar resurfacing remains controversial in modern TKA, excellent outcomes are achievable with, and without, primary patellar resurfacing. Selectively leaving the patella unresurfaced when there is limited patellar arthritis may not only be highly effective, but it may also limit the incidence of secondary resurfacing that may occur with more substantial patellar arthritis while also minimizing the risk of some of the devastating complications that can occur due to patellar resurfacing in TKA.
