Patellar Component Design Does Not Impact Clinical Outcomes in Primary Total Knee Arthroplasty

Round or oval implants are used in patellar resurfacing during total knee arthroplasty (TKA). However, whether component geometry affects clinical outcomes is unclear. This study aimed to determine if one implant shape conferred superior outcomes to the other.

A retrospective review of primary TKA cases performed from 2016 to 2020 was conducted at an urban, tertiary academic center. Four hundred consecutive, primary TKAs were included in these analyses. Cases were included if a surgeon used the round design then oval design for fifty consecutive cases. Baseline demographic data and radiographic measurements were assessed. Surgical data, reasons for revision, and patient-reported outcome measures were analyzed. Independent samples t-test and chi-square tests were used to compare means and proportions. There were no demographic differences between the cohorts.

Postoperative patellar tilt was statistically different between the cohorts. Sixteen patients required revision surgery; however, revision rates did not differ between the cohorts. Of the 9 rounds, 1 button was revised for infection. Of the 7 ovals, 1 button was revised for infection and 1 for loosening. Veterans RAND 12 Physical Component Score at 3 months postoperatively was higher for the round cohort, but no differences were observed at 1 year.

While radiographic patellar tilt was significantly different between the cohorts, there was no clinical correlation in outcomes at 3 months or 1 year postoperatively. Longer-term follow-up studies are needed to evaluate the implications of patellar component design on outcomes and function. Nevertheless, the current study affirms that both designs are clinically equivalent which should be used to guide clinical decision-making.

Retrospective Cohort.