Patellar fracture mapping: characteristics of fracture line distribution and risk factors for postoperative...

This study aimed to investigate the association between specific fracture line distributions and patellar fracture malreduction by generating patellar fracture maps and analyzing preoperative and postoperative computed tomography (CT) data. The goal was to identify risk factors influencing postoperative patellar malposition to guide surgical management and improve prognosis.

Imaging data of 193 patients with patellar fractures who underwent surgical treatment at Hebei Medical University Third Hospital from January 2020 to May 2025 were reviewed. Patellar fractures were virtually reconstructed and reduced using Mimics 21.0 software. Fracture lines were superimposed onto a standard template to establish a 3D fracture map for distribution analysis. Postoperative patellar positional changes were assessed using X-ray and CT measurements. Correlations between fracture line characteristics and postoperative malposition were analyzed.

A total of 193 patients (118 males, 75 females; mean age: 51.30 ± 12.59 years) were included. Transverse fractures (n = 141) primarily involved the mid-lower poles with higher fracture line density on the lateral surface. Comminuted fractures (n = 42) exhibited a radial distribution concentrated in the center; the inferior non-articular zone was prone to laminar and comminuted patterns. Fracture mapping revealed a distinct isolated medial fragment formed by intersecting fracture zones in the medial upper-middle 1/3 of the patella. This isolated medial fragment was significantly associated with postoperative lateral displacement (P < 0.001). Additionally, laminar and comminuted fractures of the inferior pole were significantly correlated with postoperative inferior displacement (P < 0.001). A significant difference in the inferior pole distance was observed between patients with and without postoperative inferior displacement (38.39 ± 5.25 mm vs. 42.68 ± 5.88 mm, P < 0.001). Gender was not associated with malposition (P > 0.05).

Fracture line mapping effectively elucidates the distribution characteristics of patellar fractures. The presence of an isolated medial fragment serves as an indicator of increased risk for postoperative lateral patellar displacement. Consequently, intraoperative management should prioritize the minimization of soft tissue stripping and the secure fixation of this fragment; when necessary, imbrication of the medial soft tissues should be performed to maintain patellar alignment. For comminuted fractures, particularly those involving lamination and comminution of the non-articular surface of the inferior pole, achieving sufficiently rigid fixation is essential. Such reinforced stability is likely required to minimize the risk of elongation, serving as the prerequisite for safe, early functional rehabilitation.