Graft shape affects midfoot correction and forefoot loading mechanics in lateral column lengthening osteotomies.

Adult acquired flatfoot deformity is characterized by midfoot abduction and collapse of the medial longitudinal arch. Lateral column lengthening osteotomies primarily correct the abduction deformity, but the effects of graft shape on deformity correction and forefoot loading are unclear. Therefore, the purpose of this study was to demonstrate the effect of graft shape and taper on deformity correction and forefoot loading mechanics in a cadaveric flatfoot model. Flatfoot deformity was simulated in 18 cadaveric specimens. A lateral column lengthening osteotomy was performed using a triangular, trapezoidal, and rectangular graft for each specimen. During each testing condition, talonavicular joint angles and forefoot plantar pressures were measured. Each graft shape corrected abduction and dorsiflexion deformity at the talonavicular joint. Coronal plane correction was affected by graft shape, and the less tapered trapezoidal and rectangular grafts overloaded the lateral forefoot compared to the intact condition. The more tapered triangular graft did not cause a lateral shift in forefoot pressures. Forefoot plantar pressures were strongly correlated with talonavicular abduction correction (R (2) = .473, P < .001). Graft shape had no effect on the correction of talonavicular abduction or dorsiflexion but did influence coronal plane motion and forefoot loading mechanics. Also, overcorrecting the abduction deformity was predictive of increased lateral plantar pressures. 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.

Baxter JR ，Demetracopoulos CA ，Prado MP ，Gilbert SL ，Tharmviboonsri T ，Deland JT ... -  《-》

Lateral column lengthening corrects hindfoot valgus in a cadaveric flatfoot model.

Adult-acquired flatfoot deformity requires a complex operative plan that often utilizes a number of procedures to correct deformity, at both the hindfoot and midfoot. A lateral column lengthening procedure is typically performed to correct abduction deformity across the talonavicular joint; however its effect on hindfoot alignment is not well understood, and overcorrecting the hindfoot deformity can lead to pain and revision surgeries. Therefore, understanding the effect of lateral column lengthening on hindfoot alignment is important for operative planning. The aim of this study was to demonstrate the effect of a lateral column lengthening osteotomy on hindfoot valgus in a simulated flatfoot model. A flatfoot deformity was created in 12 lower limb cadaveric specimens. A step-cut lateral column lengthening osteotomy was performed and changes in hindfoot and midfoot alignment were measured using a motion capture system. The lateral column lengthening procedure corrected 60% of the hindfoot valgus deformity (P < .001). In addition, the abduction deformity at the midfoot was completely corrected with the procedure (P < .001). Our findings suggest that the lateral column lengthening procedure corrects hindfoot valgus, in addition to midfoot abduction, in a flatfoot deformity. Understanding the relative contribution of each operative procedure to the overall deformity correction in flatfoot reconstruction will allow surgeons to accurately correct the foot into a plantigrade position while minimizing the risk of overcorrection.

Baxter JR ，Demetracopoulos CA ，Prado MP ，Tharmviboonsri T ，Deland JT ... -  《-》

Effect of graft shape in lateral column lengthening on tarsal bone position and subtalar and talonavicular contact pressure in a cadaveric flatfoot model.

Lateral column lengthening (LCL) has been used for correction of flatfoot deformity. The purpose of this study was to determine the effect of LCL graft shape on tarsal bone position and talonavicular and subtalar joint pressure. A flatfoot model was created in 6 cadaveric specimens. Corrective LCL was performed using a rectangular graft or a trapezoidal graft with the broad surface oriented dorsally, laterally, or plantarly. Bony surface markers were digitized to calculate angular parameters used in the evaluation of flatfoot deformity. Contact pressure and area in the subtalar and talonavicular joints were also recorded. All measurements were carried out under multiple axial loads in the intact and flatfoot conditions, and following LCL with each graft shape. Flatfoot creation resulted in significant changes in arch collapse and forefoot abduction. LCL with a rectangular graft best corrected these parameters, while a laterally oriented trapezoidal graft provided some correction. Talonavicular contact pressure was unchanged after flatfoot creation, and was significantly less than intact after LCL. Subtalar contact pressure decreased in some conditions after flatfoot creation, and decreased further after LCL. LCL with a rectangular graft best restored tarsal bone orientation in a cadaveric flatfoot model. The decreases in talonavicular pressure likely represent redistribution of force from the medial to lateral foot. When performing LCL for flatfoot deformity, increased bone graft volume medially better restores tarsal bone position. One way of achieving this is through the use of a rectangular graft as opposed to a trapezoidal graft.

Campbell ST ，Reese KA ，Ross SD ，McGarry MH ，Leba TB ，Lee TQ ... -  《-》

Operative treatment of the difficult stage 2 adult acquired flatfoot deformity.

Mosier-LaClair S ，Pomeroy G ，Manoli A 2nd 《Foot and Ankle Clinics》

Lateral column calcaneal lengthening, flexor digitorum longus transfer, and opening wedge medial cuneiform osteotomy for flexible flatfoot: a biomechanical study.

Benthien RA ，Parks BG ，Guyton GP ，Schon LC ... -  《FOOT & ANKLE INTERNATIONAL》