Externalized metaphyseal locked plating of complex proximaltibial fractures. clinical and biomechanical outcomes

Objective: The study aimed to evaluate the outcomes of using a metaphyseal distal femur locking plate as a definitive external fixator for treating complex multifragmentary proximal tibial fractures based on analysis of clinical results and biomechanical experimental Finite Element study. Methods:An ipsilateral LISS DF plate was used as an external fixator in 7 high energy multifragmentary proximal metaphyseal tibial fractures with simple intrarticular involvement in 7 patients. The mean follow-up was 22 months (range, 14 - 48 months). Moreover, static axial compression tests were performed to evaluate the strength of the fixation technique by assessing stiffness of the contruct,interfragmentari motions and strain at the fracture site. Results: The mean fracture healing time was 23.7 weeks (range, 18 - 32 weeks). At 4 weeks postoperatively and at the final follow-up, the average Hospital for Special Surgery(HSS) knee score was 86 (range, 72 - 93) and 96 (range, 88 - 100), respectively, and the American Orthopaedic Foot and Ankle Society(AOFAS) score was 92 (range, 84 - 100) and 99 (range, 95 - 100), respectively. Based on FE analysis, construct stiffness was 655 N/mm (IC-1), 197 N/mm (IC-2) and 128 N/mm (IC-3). Interfragmentary motions under partial weightbearing were 0.31 mm (IC-1), 1.09 mm (IC-2) and 1.74 mm (IC-3), whereas under full weight-bearing were 0.97 mm (IC-1), 3.50 mm (IC-2) and 5.56 mm (IC-3) respectively. The corresponding longitudinal strains at the fracture site under partial weightbearing were 1.55%(IC-1),5.45%(IC-2)and 8.70%(IC3).Conclusions: The clinical outcomes confirmed that definitive externalized locked plating could be an effective alternative treatment option in selected cases with complex proximal tibial fractures after obtaining an appropriate fracture reduction.The static axial loading of a virtual biomechanical model with simulated thin and thick soft tissue envelope, seems to ensure favorable conditions for callus formation with longitudinal strains at the fracture site not exceeding 10%, thus providing an adequate relative stability for indirect bone healing under early partial weightbearing.