Graft Shape Affects Midfoot Correction and Forefoot Loading Mechanics in Lateral Column Lengthening Osteotomies

Abstract

Although overcorrection of the abduction deformity at the midfoot remains the primary determinant of lateral forefoot overload, utilizing a graft with a larger taper may lower the incidence of lateralized forefoot pressure following correction.

How Do Hindfoot Fusions Affect Ankle Biomechanics: A Cadaver Model

“…The experimental apparatus applied an axial force to the tibia (and rigidly fixed fibula) without the capacity for physiologic transverse plane torque. In addition, although the Achilles tendon was loaded, the other extrinsic tendons were sectioned proximal to the ankle, but these tendon loads are very small compared with Achilles tension during locomotion [2]. However, in vitro biomechanical testing offers an important insight by allowing the investigator to prescribe precise loads and to control for variations in anatomy by applying sequential fusions and testing in individual specimens.…”

“…2 body weight of a standardized 800-N (approximately 180 pounds) individual, whereas the Achilles tendon load transferred load through the midfoot, which is common in standing [1,2,12,26]. Body weight was standardized to optimize the reproducibility of the experimental setup to apply and detect prescribed loads.…”

“…decreases in total force (445 ± 142 N, 95% CI, 340-550 N, versus 588 ± 118 N, 95% CI, 500-676 N; p \ 0.001) and contact area (282 mm 2 , 95% CI, 222-342 mm 2 , versus 336 ± 96 mm 2 , 95% CI, 265-407 mm 2 ; p \ 0.026) detected during loading in the neutral position; these changes also were seen in the everted foot position. Hindfoot arthrodesis also was associated with increased external rotation of the tibiotalar joint during loading: subtalar arthrodesis in the neutral loading position (3.3°± 1.6°; 95% CI, 2°-4.6°; p = 0.004) and everted loading position (4.8°± 2.6°; 95% CI, 2.7°-6.8°; p = 0.043); double arthrodesis in neutral (4.4°± 2°; 95% CI, 2.8°-6°; p = 0.003) and inverted positions (5.8°± 2.6°; 95% CI, 3.7°-7.9°; p = 0.002), and triple arthrodesis in all loaded orientations including neutral (4.5°±…”

Lateral Column Lengthening Corrects Hindfoot Valgus in a Cadaveric Flatfoot Model

“…Each of these graft geometries have been shown to correct deformity of the midfoot and alter forefoot plantar loading. 2 During testing, the graft was placed in the superior space of the osteotomy site and the base of the implant was aligned to be flush with the lateral border of the anterior segment of the calcaneus. External fixators (Hoffmann II Micro External Fixation System, Stryker Corporation, Kalamazoo, MI, USA) were placed on each side of the osteotomy on the medial and lateral borders of the calcaneus ( Figure 2B).…”

“…Medializing calcaneal osteotomies (MCO) correct the hindfoot valgus deformity 5,10 while lateral column lengthening (LCL) osteotomies provide substantial correction to the midfoot deformity. 2,13,19 Although patient outcomes typically improve following these procedures, overcorrecting the flatfoot deformity can lead to eversion stiffness, lateral column overload, and postoperative pain. 8,13 Hindfoot alignment is an important consideration in the treatment of flatfoot deformity and is strongly related to the amount that the calcaneus is medialized during a MCO.…”