Early Radiological Outcome of Minimally Invasive Bunion Correction Using a Guided Trajectory System

Category: Bunion; Other Introduction/Purpose: Hallux Valgus correction with Minimally Invasive Surgery (MIS) is a popular procedure due to its potential advantages such as shorter operative time and quicker recovery than open surgery. Third-generation Minimally Invasive Chevron Akin (MICA) osteotomy has shown excellent clinical and radiological outcomes. The optimal fixation criteria are 3-point fixation (medial cortex, lateral cortex, and the lateral half of the 1st metatarsal head) for the proximal screws and 2-point fixation (medial cortex and central position in the 1st metatarsal head) for the distal one. To address the steep learning curve of the free hand technique, we describe a new guided trajectory system for third-generation MICA to increase precision and reduce the risk of suboptimal K-wire or screw placement. Early radiological outcomes and complications were reported. Methods: From April 2022 to January 2023, 13 consecutive MICAs were performed on 11 female patients (bilateral in 2 patients) with an average age of 61 by a single fellowship-trained foot and ankle orthopaedic surgeon who developed the device. These were the 13 first cases performed with the new device. Preoperative and postoperative intermetatarsal angle (IMA), hallux valgus angle (HVA), distal metatarsal articular angle (DMAA) and tibial sesamoid position (TSP) were measured in all patients using weight-bearing radiographs. Also evaluated in the postoperative radiographs were the number of cortical purchase of the screws and their position in the metatarsal head. Additionally, any difficulties or intraoperative complications and operative time were reported. All parameters were analysed with the one-tailed non-parametric Wilcoxon test. Results: All the radiographic parameters improved significantly. The median IMA improved from 14.5 degrees (interquartile range [IQR]: 11.5-16) to 5 degrees (IQR: 4.0-6.0) (p < 0.005). The median HVA also decreased from 27.5 degrees (IQR: 25.3-34.5) to 7.0 degrees (IQR: 4.0-8.5) (p < 0.005). The median DMAA fell from 15.5 degrees (IQR: 13.3-19.3) to 6.0 degrees (IQR: 6.0-8.0) (p < 0.005). The median TSP was 2 (IQR: 2-3) pre-operatively and 0 (IQR : 0-1) (p < 0.005) post-operatively. All the proximal screws for Chevron osteotomy had 3-point fixation and the distal anti-rotation screws had 2-point fixation No intraoperative complications were reported. The mean operative time was 52 (SD:10,4) minutes. Conclusion: Our study demonstrates the successful use of a guided trajectory system for minimally invasive bunion correction with optimal screw placement, good early radiological outcomes, and without extensive operating time. The absence of intraoperative complications or difficulties further confirms the efficacy of this system. Our findings suggest that the use of a guided trajectory system can potentially improve the consistency and success of third-generation MICA procedures. These results emphasize the benefits of incorporating guided trajectory systems in bunion correction surgeries and their potential to improve patient outcomes.