INCIDENCE OF PATELLAR CREPITUS IN PRIMARY TOTAL KNEE ARTHROPLASTY USING A CONSTRAINED CONDYLAR IMPLANT DESIGN

Background/Aims Patellar crepitus (PC) is a noteworthy complication in posterior stabilized (PS) total knee arthroplasty (TKA). Proposed etiologies include implant design, position, and previous surgical procedures. This study compared PC incidence with use of a constrained condylar (CCD) versus PS design implant in primary TKA. Methods An institutional database review identified 63 TKA patients implanted with a CCD (Attune CRS) who were matched 1:1 to a control group receiving a standard PS design (Attune PS; 126 participants) for primary TKA. Pre- and postoperative demographics, functional outcome scores, clinical variables, and postoperative radiographic metrics were compared. Implant design characteristics such as trochlear groove geometry and intercondylar box ratio, were analyzed. Statistical analysis utilized two-sample t-tests (significance level of p < 0.05). Results The incidence of postoperative PC was 7.94% for the CCD cohort versus 3.17% for the PS group (p=0.4397). No statistical differences were identified between groups regarding general demographics (age, gender, BMI, and follow-up duration) or preoperative Knee Society Scores. Trochlear design differences between femoral components were minimal with a slightly higher intercondylar box ratio in the CCD design. The CCD cohort presented with lower preoperative knee flexion (104.4° vs. 112.8°, p=0.0339), a higher number of prior surgeries (0.8 vs. 0.4, p=0.0092), and a greater prevalence of post-traumatic osteoarthritis (46.03% vs. 20.63%, p=0.0043). Furthermore, the CCD group had a higher incidence of lateral retinacular release (11 vs. 0, p=0.0005) and greater posterior tibial offset (11.8 mm vs. 8.8 mm, p<0.0001). Other statistical differences in postoperative variables were not observed. Conclusions The incidence of PC in primary TKA using a CCD versus a PS implant was statistically comparable. This suggests other factors such as a higher incidence of previous operative procedures and a diagnosis of post-traumatic arthritis may be more important factors resulting in PC following primary TKA.