RESUMO
Hallux valgus is one of the most common surgically corrected forefoot deformities. Studies evaluating clinical outcomes of minimally invasive chevron and akin (MICA) procedure have shown shorter operation time, faster recovery, and smaller scars compared to the open approach. Previous biomechanical cadaveric studies have largely focused on the open approach with minimal on MICA. To our knowledge, no studies have compared different proximal screw placements in MICA which can either be three-point fixation or intramedullary. This study aims to compare the biomechanical properties of fixation between these two techniques in MICA. Six matched pairs of human fresh frozen cadaveric feet were randomized to either three-point fixation or intramedullary groups. Both procedures were performed by a single fellowship-trained orthopaedic foot and ankle surgeon. Using a material testing machine, each specimen underwent 1000 cycles of plantar-to-dorsal uniaxial loads from 0 to 31 N in cantilever configuration while monitoring bending stiffness and distal fragment dorsal angulation. They were then subjected to load until failure at a compression rate of 10 mm/min. Specimens from both groups tolerated the walking fatigue test. Mean bending stiffness of three-point fixation was 84% higher than intramedullary constructs (P=0.002). Mean dorsal angulation of intramedullary was thrice that of three-point fixation constructs (P=0.008). Mean load to failure of three-point fixation was 30% higher than intramedullary constructs (P=0.001). Three-point fixation provide superior biomechanical stability compared to intramedullary proximal screw placement. The surgical technique using three-point proximal screw fixation can offer robust fixation and lead to better clinical outcomes. LEVEL OF CLINICAL EVIDENCE: 5.
