Abstract

Background
This study investigated the characteristics of lateral marginal fractures of the patella and evaluated the clinical outcomes.
Methods
We retrospectively reviewed all patients with lateral marginal fractures of the patella, defined as a vertical fracture line within 15 mm of the lateral patellar border, from 2008 to 2020. In total, 41 patients were included. Patient characteristics, radiologic findings, and clinical outcomes, including the Lysholm score at 1 year postoperation, were evaluated.
Results
The injury mechanisms were direct in 34 cases and indirect in seven. Furthermore, 85% of patients had a skyline view of the patella at the initial visit, and one medial subluxation of the patella was found. Forty of the 41 patients underwent surgery. Anatomical and nonanatomical (>1-mm displacement or excision) reductions were carried out in 36 cases (88%) and 5 cases (12%), respectively. The average Lysholm score was 89.1 (range, 67–99). The nonanatomical reduction group had a poorer functional score (79.8 vs. 90.4; P=0.010). Lateral patellar compression syndrome occurred in two patients with nonanatomical reduction.
Conclusions
Lateral marginal fractures of the patella affected patellofemoral stability. Anatomical reduction showed good functional outcomes, while nonanatomical reduction was associated with patellofemoral stability and pain. Therefore, surgeons should perform anatomical reduction with any appropriate fixation method. Level of Evidence: IV

• Keywords: Patella; Patellofemoral joint; Marginal fracture; Lateral marginal; Outcomes; Complications