Morphological Characteristics of Inferior Pole Patellar Fractures and a Finite-Element Analysis Combined With a Retrospective Clinical Study of Anchor Suture and Titanium Cable Cerclage Treatment

Objective: Inferior pole patellar fractures (IPPFs) pose a significant challenge due to their complex fracture patterns and high risk of complications associated with current treatment methods. This study aims to (1) characterize the fracture patterns of IPPFs using fracture mapping and (2) compare the biomechanical stability and clinical outcomes of treatment with anchor suture with patellar cerclage versus Kirschner-wire tension band combined with patellar cerclage.

Methods: (1) A retrospective analysis was conducted on 61 patients with IPPF. For each case, fracture reduction was manually simulated, with fracture lines and fragments overlaid onto a complete patella template to identify fracture patterns. (2) Finite-element models were used to analyze the mechanical properties of anchor suture and titanium cable cerclage treatment and Kirschner-wire tension band combined with patellar cerclage in treating IPPFs. Additionally, a retrospective analysis of clinical data was performed on 57 patients with IPPF (AO/OTA 34 A1) treated at our institution between January 1, 2023, and December 25, 2023. Of these, 18 patients underwent anchor suture and titanium cable cerclage (Group A), and 39 underwent Kirschner-wire tension band combined with patellar cerclage (Group B). We compared operative time, final knee range of motion, incidence of secondary surgery, postoperative complications, and functional recovery between the two groups based on medical records and follow-up results.

Results: (1) IPPFs were predominantly comminuted, with fracture lines on the anterior view concentrated laterally and near the superior surface of the inferior pole. Fracture lines became more sparse as they approached the distal patella. The posterior view was similar to the anterior, with the majority of fractures near the superior surface of the inferior pole. (2) Finite-element analysis revealed no significant differences between the two groups in terms of displacement and stress. Operative time was similar between the groups (p > 0.05), as were final knee range of motion (p > 0.05) and postoperative Bostman scores (p > 0.05). Group A had no postoperative complications or readmissions, while Group B had two cases of hardware irritation and one case of knee joint infection.

Conclusion: The fracture lines of IPPF are varied, often comminuted, and correlate with the mechanism of injury. Biomechanical and clinical outcomes suggest that anchor suture with patellar cerclage is a viable option for stabilizing IPPF.

Trial registration: ClinicalTrials.gov identifier: NCT06736639.