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Ligamentous Lisfranc injuries cause debilitating pain and loss of function. Even small diastasis of this normally rigid joint after injury requires surgical treatment, but outcomes remain poor. Existing literature has compared the different surgical procedures using cadaveric models, but no approach has been recommended over others. This study uses a computational biomechanical approach consistent with a cadaveric study to evaluate the different procedures' ability to stabilize the Lisfranc joint without inducing secondary consequences. A validated rigid body model for the cadaver foot with a Lisfranc injury was extended to compare the stability of four different surgical repairs-three open reduction and internal fixation procedures with different hardware (cannulated screws, endobuttons, and screws with a dorsal plate) and primary arthrodesis with screws. Forces calculated from the rigid body model for 50% partial weight bearing provided boundary conditions for a finite element model of the surgical repairs. Comparing the different surgical procedures, the open reduction and internal fixation with screws and primary arthrodesis with screws showed the most stable postoperative Lisfranc joint. However, the use of cannulated screws for fixation showed regions of high stress that may be susceptible to breakage and also resulted in higher contact forces in joints adjacent to the surgery site. Endobuttons and dorsal plates did not restore sufficient stability. Since all procedures showed different points of concern that could impact outcomes, additional surgical approaches could be needed in the future. This study offers a standard protocol for benchmarking the new procedures against those currently used. Published version

Several surgically corrective procedures are considered to treat Adult Acquired Flatfoot Deformity (AAFD) patients, relieve pain, and restore function. Procedure selection is based on best practices and surgeon preference. Recent research created patient specific models of AAFD to explore their predictive capabilities and examine effectiveness of the surgical procedure used to treat the deformity. The models' behavior was governed solely by patient bodyweight, soft tissue constraints, muscle loading, and joint contact without the assumption of idealized joints. The current work expanded those models to determine if an alternate procedure would be more effective for the individual. All procedures incorporated first a tendon transfer and then included one hindfoot procedure, the Medializing Calcaneal Osteotomy (MCO), and one of three lateral column procedures: Evans osteotomy, Calcaneocuboid Distraction Arthrodesis (CCDA), Z osteotomy, and the combination procedures MCO & Evans osteotomy, MCO & CCDA, and MCO & Z osteotomy. The combination MCO & Evans and MCO & Z procedures were shown to provide the greatest amount of correction for both forefoot abduction and hindfoot valgus. However, these two procedures significantly increased joint contact force, specifically at the calcaneocuboid joint, and ground reaction force along the lateral column. With exception to the lateral bands of the plantar fascia and middle spring ligament, the strain present in the plantar fascia, spring, and deltoid ligaments decreased after all procedures. The use of patient specific computational models provided the ability to investigate effects of alternate surgical corrections on restoring biomechanical function in these flatfoot patients. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1523-1531, 2017.

Several surgically corrective procedures are considered to treat Adult Acquired Flatfoot Deformity (AAFD) patients, relieve pain, and restore function. Procedure selection is based on best practices and surgeon preference. Recent research created patient specific models of AAFD to explore their predictive capabilities and examine effectiveness of the surgical procedure used to treat the deformity. The models' behavior was governed solely by patient bodyweight, soft tissue constraints, muscle loading, and joint contact without the assumption of idealized joints. The current work expanded those models to determine if an alternate procedure would be more effective for the individual. All procedures incorporated first a tendon transfer and then included one hindfoot procedure, the Medializing Calcaneal Osteotomy (MCO), and one of three lateral column procedures: Evans osteotomy, Calcaneocuboid Distraction Arthrodesis (CCDA), Z osteotomy, and the combination procedures MCOEvans osteotomy, MCOCCDA, and MCOZ osteotomy. The combination MCOEvans and MCOZ procedures were shown to provide the greatest amount of correction for both forefoot abduction and hindfoot valgus. However, these two procedures significantly increased joint contact force, specifically at the calcaneocuboid joint, and ground reaction force along the lateral column. With exception to the lateral bands of the plantar fascia and middle spring ligament, the strain present in the plantar fascia, spring, and deltoid ligaments decreased after all procedures. The use of patient specific computational models provided the ability to investigate effects of alternate surgical corrections on restoring biomechanical function in these flatfoot patients. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1523-1531, 2017.