Effects of Degree of Surgical Correction for Flatfoot Deformity in Patient-Specific Computational Models

Abstract

A cohort of adult acquired flatfoot deformity rigid-body models was developed to investigate the effects of isolated tendon transfer with successive levels of medializing calcaneal osteotomy (MCO). Following IRB approval, six diagnosed flatfoot sufferers were subjected to magnetic resonance imaging (MRI) and their scans used to derive patient-specific models. Single-leg stance was modeled, constrained solely through physiologic joint contact, passive soft-tissue tension, extrinsic muscle force, body weight, and without assumptions of idealized mechanical joints. Surgical effect was quantified using simulated mediolateral (ML) and anteroposterior (AP) X-rays, pedobarography, soft-tissue strains, and joint contact force. Radiographic changes varied across states with the largest average improvements for the tendon transfer (TT) + 10 mm MCO state evidenced through ML and AP talo-1st metatarsal angles. Interestingly, 12 of 14 measures showed increased deformity following TT-only, though all increases disappeared with inclusion of MCO. Plantar force distributions showed medial forefoot offloading concomitant with increases laterally such that the most corrected state had 9.0% greater lateral load. Predicted alterations in spring, deltoid, and plantar fascia soft-tissue strain agreed with prior cadaveric and computational works suggesting decreased strain medially with successive surgical repair. Finally, joint contact force demonstrated consistent medial offloading concomitant with variable increases laterally. Rigid-body modeling thus offers novel advantages for the investigation of foot/ankle biomechanics not easily measured in vivo.

Computational analysis of the clinical presentation of a ligamentous Lisfranc injury

“…Such models have been successful in examining high-frequency injuries or deformities such as ankle sprains, arch stability, and flatfoot deformity. [12][13][14][15] However, this has left other less common injuries without models or information on their biomechanical behavior. The goal of this study was to create a computational model and confirm it could replicate previously published biomechanics for Lisfranc injuries.…”

“…Selection of the ligament insertion locations, as well as stiffness values, were informed by previous foot and ankle models as well as additional sources from the literature where the ligaments were modeled as linearly elastic with individual element stiffnesses ranging from 30 to 200 N/mm. 13,[15][16][17][18][19][20][21] To account for the in situ tension existing in these structures, a uniform 3% strain was assumed in the neutral scan position.…”

Patient specific computational models to optimize surgical correction for flatfoot deformity

“…The challenge with having multiple surgical combinations available is to select the optimal procedure(s) for the individual patient. Computer Aided‐Design (CAD) modeling has been employed to recreate the anatomy and kinematics of the foot and ankle complex in both the intact and diseased states as well as replicating possible surgical procedures . While providing insight into function of the foot/ankle complex as a whole, the use of the CAD models also allowed for exploration into the variations in surgical techniques employed, specifically the amount of MCO translation, from 5 to 15 mm.…”

“…While providing insight into function of the foot/ankle complex as a whole, the use of the CAD models also allowed for exploration into the variations in surgical techniques employed, specifically the amount of MCO translation, from 5 to 15 mm. More recently, rigid‐body kinematic analyses have been used to create patient specific models replicating both the diseased state at initial presentation and the corrected surgical state of each patient . The current work expands on these patient specific models by investigating the effects of adding lateral column treatments to the MCO and FHL tendon transfer, the treatment used by the surgeon for such patients, as these other surgical procedures would be considered clinically to treat a presenting patient.…”

Capturing the 2019 H. R. Lissner Medal Presentation With Jennifer S. Wayne

“…Subsequently, we developed pre-and postoperative subjectspecific models for patients planning to undergo an MCO [10][11][12]. An magnetic resonance imaging of each subject's lower leg was used for 3D anatomy capture and tissue assessment.…”