Incidence of Postoperative Patellar Crepitus in Total Knee Arthroplasty with Unresurfaced Patellae in Cruciate-Retaining and Posterior-Stabilized Designs.

BACKGROUND: Patellar crepitus is a complication most seen in patients implanted with a posterior-stabilized (PS) total knee arthroplasty (TKA). The primary objective of the study was to examine the incidence of patellar crepitus in unresurfaced patellae in modern PS- and cruciate-retaining (CR)-TKA designs.

METHODS: A retrospective review of 845 patients who underwent TKA whose patellae were left unresurfaced and had a 1-year minimum postoperative follow-up were included in the study. Patellar crepitus incidence (symptomatic versus asymptomatic), patient demographics, implant design, release performed, function, and patient-reported outcomes were recorded. Reoperations and adverse events were documented. Statistical analyses were performed to determine differences in incidence of crepitus and both clinical and functional outcomes.

RESULTS: The overall incidence of postoperative crepitus was 9.8% (83 of 845). The PS knees were more likely to develop crepitus than CR knees (12.3% (65 of 527) versus 5.7% (18 of 318); P = 0.0002). Of the 83 patients who developed crepitus, 14 patients had painful crepitus, and ultimately, six patients underwent reoperation due to crepitus. The type of femoral implant design was significantly associated with the incidence of crepitus postoperatively (P = 0.0003). The CR TKA design was associated with the lowest incidence of developing postoperative crepitus. Patients who had preoperative crepitus were more likely to require a release (P = 0.0207), and those who developed crepitus postoperatively were also significantly more likely to require release during surgery compared to those who did not develop crepitus (P < 0.0001).

CONCLUSIONS: In the setting of modern TKA designs, PS-TKA implants demonstrated a higher incidence of postoperative crepitus than CR-TKA implants in those with unresurfaced patellae. Most patients who had crepitus remain asymptomatic. These data may assist providers in appropriate education for patients regarding crepitus in unsurfaced patellae.