Finite element analysis and clinical efficacy of hyperextension bicondylar tibial plateau fractures fixed by medial and lateral dual plates and spinal cage
Authors: Xu Yibo , Lu Yao , Huang Qiang , Ren Cheng , Li Ming , Zhao Guolong , Wang Qian , Bai Huanan , Du Bing , Ma Teng , Li Zhong , Zhang Kun 
Published: January 2023

Abstract
Purpose To elucidate the biomechanical characteristics of fracture defect filled with spinal cage by finite element analysis, and investigate the clinical efficacy of medial and lateral dual plates with spinal cage for the treatment of hyperextension bicondylar tibial plateau fractures.
Methods A 10-mm cuneiform defective osteotomy of proximal tibia was created in the finite element model to simulate hyperextension bicondylar tibial plateau fractures. The defect area in the established model was filled with spinal cage (Group A) or allograft bones (Group B) after fracture reduction. The biomechanical properties of both models were tested under axial compression loading and the maximum displacement of the fragments was recorded. Furthermore, a retrospective analysis was conducted on 12 patients with hyperextension bicondylar tibial plateau fractures who were surgically treated at the Lower Limb Surgery Ward of Traumatic Orthopedic Department, Xi’an Honghui Hospital from January 2020 to January 2022. The gender, age, cause of injury, associated injury, the preoperative and postoperative posterior tibial slope angle (pTSA), duration between injury and operation, surgical duration, intraoperative blood loss, complications, time of bone healing, time of weight bearing, Rasmussen radiological criteria and HSS scores were collected and analyzed.
Results The finite element model showed that the maximum displacement in Group A was 0.1006 mm and that in Group B was 0.1203 mm, whereas the maximum stress in the two groups were 39.70 MPa and 43.69 MPa respectively. Therefore, implantation of spinal cage into the bone defect area after fracture reduction has obvious biomechanical advantages. We also analyzed 12 patients (9 males and 3 females, aged ranging from 27 to 66 years with mean age of 46.0 ± 12.3 years) with Schatzker type VI fractures. The patients were successfully followed up for an average of 12.50 ± 3.37 months (8 to 18 months). The postoperative pTSA was significantly improved related to the preoperative pTSA (P < 0.001). The average duration between injury and operation was 6.08 ± 2.78 days, the average surgical duration was 131.67 ± 32.71 min, and the average intraoperative blood loss was 320.83 ± 113.73ml. Furthermore, the average time of bone healing was 13.58 ± 2.57 weeks and the average time of weight-bearing was 8.33 ± 2.93 weeks. In addition, 33.33% of postoperative complications was observed in 1 case of superficial wound infection and dehiscence, 1 case of delayed union combined with limited range of motion of the knee joint and 2 cases of deep vein thrombosis. The excellent and good rates of Rasmussen radiological criteria and HSS scores were 83.33% and 91.67% respectively.
Conclusion Fracture reduction and fixation by medial and lateral dual plates and spinal cage is an effective method for the treatment of hyperextension bicondylar tibial plateau fractures, and has biomechanical advantages such as favorable bone healing time, weight bearing time, radiographic and clinical functional outcomes.