In this analysis of 842,072 primary total knee replacements (TKR) implanted for osteoarthritis between 1st April 2003 and 31st December 2016, the patella was not resurfaced in 536,228 (64%) of the procedures and resurfaced in the remaining 305,844 (36%) of cases (1). The cumulative risk of all-cause revision surgery was significantly higher in those without than in those with patella resurfacing at primary surgery (p < 0.001). Kaplan-Meier 10-year estimates of revision rates were 3.54% and 3.00%, respectively.
Use of predictive modelling indicated that if all 536, 228 TKR without patella resurfacing had been resurfaced, then 2,841 revisions could have been avoided. This is an important finding because outcomes from revision knee surgery are less predictable than primary surgery, and can result in more pain and disability, and a loss of function and participation in society and employment. This suggests that not resurfacing the patella during primary TKR may lead to a substantial burden on the healthcare system.
Of the 2,246 TKRs that subsequently underwent a secondary patella resurfacing, 1 in 11 required a re-revision within 5 years of surgery. The risk of all-cause re-revision was nearly 5 times higher than the risk of revision after primary TKR with patella resurfacing (8.8% Vs 1.9%). It should be noted, however, that only 1 in 189 cases where the patella had not been resurfaced initially would need revising within the first 10 years. This indicates that the “absolute risk” of revision following secondary patella resurfacing is still relatively small (1).
Implant design and more specifically the shape of the trochlea/patella-femoral articulation can vary between brands, and within the same brand according to constraint. The authors highlight that this may affect the risks of secondary patella resurfacing, and emphasised that surgeons that do not routinely resurface the patella must be aware that there are significant differences in outcomes between different TKR brands and levels of constraint (1).