Patella Resurfacing and Revision Risk Study: Don’t Be Wishy Washy

To calculate the risk of revision on the basis of surgeon preference for patellar resurfacing in total knee replacement (TKR), a team from Australia mined 1999 to 2016 data from the Australian Orthopaedic Association National Joint Replacement Registry.

Their work, “The Effect of Surgeon Preference for Selective Patellar Resurfacing on Revision Risk in Total Knee Replacement,” appears in the July 17, 2019 edition of The Journal of Bone and Joint Surgery.

Co-author Christopher Vertullo, M.B.B.S., Ph.D., F.R.A.C.S. (Ortho) explained the underlying rationale for the study to OTW, “This study deals with the effects of surgeon cognition, preferences and decision making on patient outcome’s in total knee replacement, specifically examining patella resurfacing. The advantages and disadvantages of patella resurfacing have been debated for decades, nevertheless the decision to resurface or not typically remains the preference of the surgeon.”

“We know that patients who didn’t receive patella resurfacing had a higher risk of later patella revision, however, in some of our previous work we saw a dominant preference for selective patella resurfacing by surgeons rather than routine resurfacing. Surgeons who have a selective resurfacing preference did so in the belief they can successfully choose which patients require patella resurfacing and which do not to avoid later revision.”

“We used an instrumental variable analysis of Australian Orthopaedic Association Registry data to examine patient revision risk based on the patella resurfacing preference (routine, selective or infrequent) of their surgeon.”

The authors pulled 136,116 total knee procedures out of the registry data. They made sure to include patients who were in all 3 cohorts (routine, selective or infrequent patella resurfacing preference) and who also had similar demographics.

After assembling the data, the authors found that patients who were in the selectively resurfaced cohort had a higher patellar revision risk when compared to patients who were assigned to the routinely resurfaced cohort. Furthermore, the authors found that this risk tended to be strongest in the first 4.5 years following the primary procedure. Specifically, they found that the risk was 306% higher in the first 1.5 years, and 50% higher after 4.5 years.

When the authors performed a subgroup analysis, they observed higher revision risk among males, females, under 65 years of age, and any patient ≥65 years of age.

Patients who were assigned to the infrequently resurfaced cohort had the highest risk of subsequent patellar revision, up to 482% higher in the first 1.5 years after a primary procedure as compared to patients who were assigned to the routinely resurfaced cohort.

Finally, the authors noted, the risk of all-cause revision was 20% higher for the selectively resurfaced cohort as compared with patients in the routinely resurfaced cohort.

Dr. Vertullo summarized the study results to OTW, “Patients of surgeons who preferred selective patella resurfacing had a higher risk of subsequent patella revision. To reduce confounding by selection bias, we excluded PS [posterior stabilized] TKR as they have a higher rate of secondary resurfacing compared to CR [cruciate retaining] TKR and minimally stabilized TKR.”

“Surgeons who preferred infrequent resurfacing had the highest risk of subsequent revision, as high as 482% greater in the first 1.5 years. The greatest risk of patella revision occurred in the first 1.5 years after the primary procedure in all groups. In all groups, the majority of subsequent revision were undertaken by the primary surgeon, suggesting the majority of surgeons believed the later patella revision procedure may help their patients.”

“Selective patella resurfacing is a questionable method to avoid later revision. A greater preference for resurfacing results in a lower risk of subsequent patellar revision.”