ComeBack Mobility helps surgeons prescribe the optimal weight-bearing load after lower limb fractures based on biomechanical analysis. As is well known, in most cases, the optimal interfragmentary movement in the fracture zone is approximately 1 mm. Therefore, the patient should load the leg with a weight that leads to this movement while ensuring that the internal or external fixation can withstand it. To determine this load and the stability of the fixation, ComeBack Mobility provides biomechanical analysis data using FEA.
Case 1: Comminuted fracture of the distal third of the tibia stabilized with a medial plate and seven screws. Optimal interfragmentary movement up to 1mm is achieved with a load of 60 kg or 80% of the patient's body weight. However, one screw is unstable under a load of 7.5 kg or 10% of the patient's body weight due to significant bending loads from torque, making it likely to loosen during walking, and the lack of necessary interfragmentary movement will slow the formation of the bone callus.
Case 2: Tibia shaft multifragmentary fracture stabilized with intramedullary nailing. Optimal interfragmentary movement in the range of 0.5 - 1mm is achieved with a load of 15 kg to 30 kg, which is 20% to 40% of the patient's body weight. The fixation and the bone can withstand this load, but exceeding this limit will lead to movement between bone fragments in the range of 1.62-3.26 mm, which can significantly slow down the healing process.
Case 3: Patient with trimalleolar fracture. Osteosynthesis of the medial malleolus of the tibia was performed using Weber's technique. Fixation of the lateral malleolus was done with a plate and 4 screws. The posterior malleolus was not fixed. Interfragmentary movement does not exceed 0.1 mm under axial loading of the patient's full weight, provided the ankle is stabilized with an orthopedic boot.
