Radiographic OA Severity Not a PROM Predictor?!

A new paper from the Indiana University (IU) School of Medicine and the IU Health Saxony Hospital should give some measure of comfort to surgeons leaving an arthritic patella unresurfaced—in certain cases. Their retrospective review, “Osteoarthritic Severity in Unresurfaced Patellae Does Not Adversely Affect Patient-reported Outcomes in Contemporary Primary TKA,” was published in the Journal of the American Academy of Orthopaedic Surgeons.

Co-author Michael Meneghini, M.D., director of the Indiana University Health Hip and Knee Center at the Indiana University School of Medicine, explained the background of the study to OTW, “With our current understanding, it appears you can observe any degree of OA on a native patella and leave unresurfaced in total knee arthroplasty (TKA) with some caveats.”

“First, if a patient has a systemic inflammatory disease, like rheumatoid arthritis, that patella should likely be resurfaced. Further if a patella is laterally tracking with severe arthritic disease and eburnated bone on the lateral facet of the patella, we prefer to resurface those given they have sufficient patella thickness of at least 11-12 mm.”

“Otherwise, we tend to leave patellae unresurfaced. However, there is a specific treatment of an unresurfaced patella that involved release of the lateral retinacular tissue from the anterior surface of the lateral patellar facet, a lateral facetectomy and peripheral osteophyte removal.”

Dr. Meneghini and his colleagues looked at 193 primary TKAs done without patellar resurfacing and collected data for:

• the severity of the preoperative patellofemoral OA,
• marginal osteophytes,
• joint space narrowing,
• chondral damage
• patellar tilt and
• tibiofemoral alignment
• The team then evaluated PROMs at a minimum of 1-year.

Meneghini and his team found that preoperative lateral patella Kellgren-Lawrence grade ≥2 was associated with superior change in Knee Society Score pain with level walking, higher absolute change in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, and knees “always feeling normal.”

“I would say that we did not expect the finding that more severe radiographic preoperative arthritis in the lateral patellofemoral joint predicted superior patient-reported outcome measures (PROMS) in patient with unresurfaced patellae in TKA,” said Dr. Meneghini to OTW. “This would support the notion that patients with more severe arthritis at the time of TKA will do better postoperative and also supports that patella OA has minimal contribution to knee function and patient outcomes after TKA, at least in the short term.”

“There is a clear trend in the U.S. toward leaving the patella unresurfaced after TKA, and this paper provides some assurance to surgeons that the degree of radiographic severity in and of itself is not a predictor of outcome so that they can feel comfortable leaving an arthritic patella unresurfaced given the caveats that the patella is not a maltracking one and the patient does not have a systemic inflammatory disease.”