Use of Technetium Bone Scan to Help Predict Whether Patella Resurfacing Will Be Successful in Treating Pain Following Primary TKR

OBJECTIVES: Anterior knee pain is not uncommon following primary TKR. The AOANJRR (2014) reports that 12.1% of revisions of primary TKR are for patellofemoral pain. Patella resurfacing does not always relieve this pain. The objective of this study is to investigate whether a technetium bone scan after TKR will predict success of a subsequent patella resurfacing. METHODS: Observational Case Series. This is a retrospective review of patients of a single orthopaedic surgeon over a 22 year period. Patients who had subsequent isolated patella resurfacing (or patella resurfacing plus tibial insert exchange) of a primary TKR were identified and contacted by telephone. All had bone scans performed in their workup to patella resurfacing. Bone scan was considered positive if the radiologist reported greater uptake in the patella than elsewhere in the knee. Three patient outcome measures were used: Satisfaction (very satisfied, satisfied, dissatisfied, very dissatisfied); Pain relief (excellent, good, no improvement, worse); “Would you have the surgery again?” (yes, no). Correlation was made between results of bone scans and patient outcome measures. RESULTS: 35 patients were identified who underwent subsequent patella resurfacing of a primary TKR. 22 were contactable and eligible for the study. The average time from primary knee replacement to patella resurfacing was 6 years, 4 months. The average time from the patella resurfacing to interview was 3 years, 8 months. 17 of the patients did not have their patella resurfaced at the primary procedure. 5 had loose patella buttons. 3 had replacement of their tibial polyethylene insert at the same time as patella resurfacing. There were 15(68%) positive bone scans. Of these, 14(93%) were very satisfied or satisfied. There was a single case (7%) who was dissatisfied. 14(93%) had excellent or good pain relief, 1(7%) had no improvement. 14 patients said that they would have the surgery again, 1 would not. There were 7(32%) negative bone scans. Of these, 2(29%) were very satisfied or satisfied and 5(71%) were dissatisfied. 2(29%) had excellent or good pain relief, 5(71%) had no improvement. 4 patients said that they would have the surgery again, 3 would not. CONCLUSIONS: In patients with a painful primary TKR, technetium bone scan may be a useful additional tool to help predict which patients will benefit from subsequent patella resurfacing