Personalized alignment in total knee arthroplasty reduces patellar tilt: A retrospective study

Patellofemoral kinematics is crucial for patient satisfaction following total knee arthroplasty (TKA). A postoperative patellar tilt greater than 5° has been associated with inferior clinical outcomes. While a femoral component external rotation beyond 3° is generally protective against patellar tilt, personalized alignment may not consistently reach this threshold. The aim of this study is to (1) assess the incidence of postoperative patellar tilt >5° following TKA with personalized alignment and (2) identify preoperative and intraoperative factors associated with this complication.

This comparative retrospective study included 316 primary TKAs Attune (Johnson & Johnson®) performed between January and December 2024 using navigation or robotic assistance. All procedures were conducted at the same center by four surgeons: two using a subvastus approach and two a transquadricipital approach. Thirty-six involving residents were excluded. Patellar tilt is defined as an angle exceeding 5° between a line drawn along the anterior borders of the femoral condyles and a line connecting the posterior edges of the medial and lateral patellar facets on a patellofemoral skyline view 3 months postoperatively. No patients were lost to follow-up. To identify postoperative patellar risk factors, the following data were analyzed: Age, gender, body mass index, preoperative hip-knee-ankle angle, medial proximal tibial angle, lateral distal femoral angle, coronal plane alignment, functional knee phenotype, tibial slope, preoperative radiographic patellar tilt, range of motion, surgical approach, laterality, implant type (posterior-stabilized or cruciate-retaining), use of robotics or navigation, patellar resurfacing and patellar button size (if applicable).

Patellar tilt was observed in 11.8% of cases, a rate markedly lower than that reported for mechanical alignment in existing literature. Multivariate analysis identified the transquadricipital approach (odds ratio [OR]: 2.75; p = 0.02), right-sided surgery (OR: 2.63; p = 0.02) and PS implants (OR: 2.59; p = 0.04) as independent risk factors.

Personalized alignment, the subvastus approach, and cruciate-retaining implants appear to reduce the risk of postoperative patellar tilt.

Level III, retrospective cohort study.