Biomechanical analysis of minimally invasive crossing screw fixation for calcaneal fractures: Implications to early weight-bearing rehabilitation. (December 2020)

• Record Type: Journal Article
• Authors: Zhang, Haowei; Lv, Miko Lin; Liu, Yin; Sun, Wanju; Niu, Wenxin; Wong, Duo Wai-Chi; Ni, Ming; Zhang, Ming
• Is Part Of: Clinical biomechanics. Volume 80(2020)
• Publication Date: 2020-12
• Subjects: Calcaneus fracture -- Internal fixation -- Walking -- Biomechanics -- Finite element analysis; Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2020.105143
• Languages: English
• ISSNs: 0268-0033

Abstract

Abstract: Background: Minimally invasive fixation using crossing screws was believed to produce satisfactory clinical outcome whereas its stability in early weight-bearing remained controversial. This study aimed to analyze the biomechanical stability of minimally invasive fixation during balanced standing and walking stance, and provide evidence for early rehabilitation. Methods: A finite element model of foot-ankle-shank complex was reconstructed based on computed tomography and magnetic resonance images, and validated by plantar pressure of the model participant. A Sanders III calcaneal fracture was created on the model, and then fixed using crossing screws. The predicted stress distribution, fracture displacement, Bohler's angle and Gissane's angle were compared between the intact calcaneus and fracture model with the fixation. Findings: Postoperatively, the concentrated stress appeared at the junction of the calcaneus and its surrounding tissues (especially Achilles tendon, plantar fascia and ligaments) during standing and walking stances, and the stress exceeded the yield strength of trabecular bone. The longitudinal screws sustained the highest stresses and concentrated at the tips and the calcaneal tuberosity junction. The displacement of posterior joint facet, Bohler's angle, and Gissane's angle were within the acceptable range either standing or walking after the fixation. Interpretation: Early weight-bearing standing and walking after minimally invasive fixation may cause high stress concentration thereby induce calcaneus stress fractures and other complications like plantar fasciitis and heel pain, so it should not be supported. The peri-calcaneus tendons, i.e., Achilles tendon and plantar fascia, play key roles in the stabilization of the calcaneal fracture after operation. Highlights: Build and validate calcaneal fracture on the lower limb musculoskeletal model. Calcaneal fracture beard higher stress than intact foot under weight-bearing state. Early weight-bearing exercise after minimal internal fixation is not supported. Peri-calcaneus soft tissues help maintain foot stability after calcaneal fracture. Calcaneal tuberosity is the key structure of calcaneal fracture fixation.