The need for secondary resurfacing is affected by trochlear height in total knee arthroplasty

The purpose of the study was to compare the rate of secondary resurfacing in a consecutive series of five different total knee arthroplasty (TKA) systems. It was our hypothesis that different TKA design features such as sulcus angle or trochlear height influence the rate of secondary resurfacing.

A retrospective study was performed on data from patients who underwent TKA without primary patellar resurfacing from 2004 to 2012 in an university-affiliated hospital. The study cohort included 784 TKA patients (m:f = 302:482, mean age at surgery ± SD 71 ± 10). Five different cruciate-retaining TKA systems were used consecutively (Group A, Triathlon, Stryker, Switzerland (n = 296), Group B, PFC Sigma, DepuySynthes, Switzerland (n = 215), Group C, LCS, DepuySynthes, Switzerland (n = 81), Group D, Balansys, Mathys, Switzerland (n = 128), Group E, Duracon, Stryker, Switzerland (n = 64)). Data were retrospectively obtained from hospital archives. Patients demographics, age at surgery, type of TKA were noted. In addition, TKA component position was assessed on radiographs with respect to "The knee society total knee arthroplasty roentgenographic evaluation and scoring system" (TKA-RESS). Pearson Chi-square test was used to compare differences between groups (p < 0.05). There were no significant differences between the groups in terms of age, gender, and radiological outcomes.

Twenty-six of 784 patients (3.3 %) underwent secondary resurfacing due to patellofemoral pain. In group A 4/296 patients (1.4 %), in group B 15/215 patients (7 %), in group C 5/81 patients (6.2 %), in group D 1/128 patients (0.8 %), in group E 1/64 patients (1.6 %) underwent secondary patellar resurfacing during follow-up. Significantly higher rates of secondary patellar resurfacing were seen in groups B and C when compared to the others (p < 0.001). It was found that the trochlear height in these TKA was higher than in the others.

Based on the findings of this study, trochlear height influences the need for secondary patellar resurfacing. The resurfacing rate ranged from 1 to 7 %, with the highest rate in the PFC Sigma TKA.

Therapeutic study, Level III.