J Orthop Surg Res. 2026 May 3. doi: 10.1186/s13018-026-06910-4. Online ahead of print.
ABSTRACT
OBJECTIVE: To investigate specific radiological risk factors in patients with patellar dislocation accompanied by inferomedial patellar margin avulsion fractures and provide evidence for clinical treatment strategy selection, this study conducted comparative analysis of radiographic measurements and clinical function between patients with patellar dislocation with and without such avulsion fractures.
METHODS: A total of 73 patients with patellar dislocation who underwent medial patellofemoral ligament (MPFL) reconstruction at the Affiliated Hospital of Chengde Medical University were included. Basic patient data, affected side, injury mechanism, and type of patellar dislocation were collected. The subjects were subsequently divided into an experimental group and a control group based on the presence or absence of a concomitant inferomedial patellar marginal avulsion fracture. Imaging evaluations, including MRI, CT, and X-ray examinations, were comprehensively performed for comparative analysis. MRI was used to assess the height of the vastus medialis obliquus (VMO); CT was used to measure patellar thickness, patellar width, lateral patellar facet angle, Wiberg angle, Wiberg index, the length ratio of lateral to medial patellar facets, trochlear depth index, sulcus angle, lateral trochlear inclination, tibial tubercle-trochlear groove (TT-TG) distance, the cross-sectional area ratio of VMO to vastus lateralis muscle (VLM), medial-lateral width of the femoral condyle, and the length of different regions of the femoral condyle, as well as to classify the patella and trochlea. The Caton-Deschamps index was measured on X-ray. Additionally, clinical function was evaluated and compared using Lysholm score, IKDC score, Tegner score, and VAS score preoperatively and at 6 months postoperatively.
RESULTS: Statistically significant differences were observed between the experimental and control groups regarding injury mechanism, type of patellar dislocation, the ratio of lateral to medial patella facet length, and Wiberg scores (P < 0.05).
CONCLUSION: Injury mechanism, types of patellar dislocation, the Wiberg angle, and the length ratio of the lateral to medial patellar facets have significant predictive value for the occurrence of avulsion fractures of the inferomedial patellar margin following patellar dislocation. Furthermore, patients with patellar dislocation, whether accompanied by avulsion fractures of the inferomedial patellar margin or not, undergoing isolated medial patellofemoral ligament reconstruction show no difference in postoperative clinical function.
PMID:42071233 | DOI:10.1186/s13018-026-06910-4
