Efficacy and biomechanical analysis of L-shaped plate treatment for osteoporotic Schatzker type II tibial plateau fractures

Abstract

BACKGROUND: Schatzker type II fractures often involve the posterolateral plateau, resulting in weakened bone strength, increased fixation challenges, and increased risk of postoperative collapse. Optimizing treatment strategies to balance stability and minimize trauma is urgently needed. OBJECTIVE: To evaluate the clinical efficacy of simple lateral L-shaped plate fixation for osteoporotic Schatzker type II tibial plateau fractures involving the posterolateral aspect, and to compare its biomechanical properties with those of lateral L-shaped plate combined with posterior T-shaped plate fixation using finite element analysis. METHODS: A retrospective analysis was conducted on 39 patients with osteoporotic Schatzker type II tibial plateau fractures involving the posterolateral aspect treated between January 2018 and December 2023 at the Department of Joint Surgery, The Second Affiliated Hospital of Soochow University. Patients were divided into L-shaped plate group (simple lateral L-shaped plate fixation, n=24) and combined group (lateral L-shaped plate combined with posterior T-shaped plate fixation, n=15). Clinical outcomes including operation time, intraoperative blood loss, bone mineral density, preoperative tibial plateau collapse, time from injury to surgery, postoperative radiological parameters (tibial plateau varus angle, posterior slope angle), knee range of motion, Hospital for Special Surgery score, and Lysholm score were compared between groups. Additionally, finite element models of Schatzker type II tibial plateau fractures were constructed based on CT data of a healthy adult male knee. Models were divided into non-osteoporotic group (A: simple L-shaped plate; B: L-shaped plate + T-shaped plate) and osteoporotic group (C: simple L-shaped plate; D: L-shaped plate + T-shaped plate). Under axial loads of 250, 500, and 750 N, overall displacement, tibial stress, and internal fixation stress were analyzed. RESULTS AND CONCLUSION: (1) Clinical results: There were no significant differences in age, sex, body mass index, bone mineral density, preoperative tibial plateau collapse, or time from injury to surgery between the two groups (P > 0.05). The L-shaped plate group had significantly shorter operation time and less intraoperative blood loss than the combined group (P < 0.0001). Immediate postoperative tibial plateau varus angle and posterior slope angle showed no significant differences between groups (P > 0.05). At final follow-up, the varus angle in the L-shaped plate group was smaller than that in the combined group (P=0.04), while the posterior slope angle still showed no significant difference (P > 0.05). At final follow-up, knee range of motion, Hospital for Special Surgery score, and Lysholm score showed no significant differences between groups (P > 0.05). (2) Finite element results: Under the same load, whether in non-osteoporotic or osteoporotic bone models, the use of T-shaped plate auxiliary fixation (groups B/D) exhibited superior performance in overall displacement and tibial and internal fixation stress compared with simple L-shaped plate fixation (groups A/C). (3) These findings suggest that for osteoporotic Schatzker type II fractures involving the posterolateral tibial plateau, simple lateral L-shaped plate fixation can achieve satisfactory reduction stability and functional recovery, with clinical outcomes comparable to double-plate technique. Finite element analysis indicates that double-plate fixation has better mechanical properties, but considering that simple lateral L-shaped plate fixation has significantly less surgical trauma and good clinical results, routine addition of posterior T-shaped plate is not necessary.

1. Introduction

Osteoporotic fractures are a common orthopedic disease that seriously threatens the health of the elderly population. Among them, osteoporotic tibial plateau fractures involving the posterolateral plateau account for a significant proportion [1]. In particular, Schatzker type II fractures have complex fracture lines, and combined with decreased bone strength in osteoporotic patients, fixation is difficult, and postoperative complications such as internal fixation failure (e.g., plateau collapse) and limited knee function are prone to occur, making it a major challenge in current clinical treatment [2-3]. Moreover, the bone healing capacity of such patients is weakened, and they often have combined soft tissue injuries, further limiting postoperative functional recovery and significantly affecting knee range of motion and quality of life [4-5].

Currently, the main surgical fixation methods for Schatzker type II tibial plateau fractures are simple lateral plate fixation or lateral plate combined with posterior plate fixation (double-plate technique) [6-7]. The former has the advantages of less trauma and simple operation, but it provides insufficient support to the posterolateral plateau, leading to a higher risk of collapse. The latter significantly enhances stability through dual support and reduces the risk of collapse, but it involves greater surgical trauma, more intraoperative blood loss, longer operation time, and consequently increases the incidence of surgical complications such as infection [7-9]. When the posterolateral fracture fragment is displaced too much or accompanied by posterolateral wall rupture, simple lateral plate reduction and fixation may be ineffective, and posterior plate combined fixation can be used. Finite element analysis, as a powerful biomechanical research tool, is widely used in orthopedics. By constructing high-precision three-dimensional models of bones and internal fixation devices and simulating mechanical responses under physiological loads, it can effectively evaluate the stability, stress distribution, and failure risk of fixation structures, providing an important basis for comparing the biomechanical properties of different internal fixation strategies [10-11]. However, most existing finite element analysis studies in the literature focus on non-osteoporotic models, and there is a lack of specific research on osteoporotic tibial plateau fractures, especially those involving the posterolateral plateau.