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Posterior tibialis tendon (PTT) dysfunction (PTTD) is associated with adult acquired flatfoot deformity. PTTD is commonly treated with a flexor digitorum longus (FDL) tendon transfer (FDLTT) to the navicular (NAV), medial cuneiform (CUN), or distal residuum of the degraded PTT (rPTT). We assessed the kinetic and kinematic outcomes of these three attachment sites using cadaveric gait simulation. Three transfer locations (NAV, CUN, rPTT) were tested on seven prepared flatfoot models using a robotic gait simulator (RGS). The FDLTT procedures were simulated by pulling on the PTT with biomechanically realistic FDL forces (rPTT) or by pulling on the transected FDL tendon after fixation to the navicular or medial cuneiform (NAV and CUN, respectively). Plantar pressure and foot bone motion were quantified. Peak plantar pressure significantly decreased from the flatfoot condition at the first metatarsal (NAV) and hallux (CUN). No difference was found in the medial-lateral center of pressure. Kinematic findings showed minimal differences between flatfoot and FDLTT specimens. The three locations demonstrated only minimal differences from the flatfoot condition, with the NAV and CUN procedures resulting in decreased medial pressures. Functionally, all three surgical procedures performed similarly.

If a researcher or clinician is interested in measuring the CPA or TNCA, the current best practices guidelines for obtaining ML and AP images should be closely followed.

Symptom relief of recalcitrant metatarsalgia can be achieved through surgical shortening of the affected metatarsal, thus decreasing plantar pressure. Theoretically an oblique metatarsal osteotomy can be oriented distal to proximal (DP) or proximal to distal (PD). We characterized the relationship between the amount of second metatarsal shortening, osteotomy plane, and plantar pressure. We hypothesized that the PD osteotomy is more effective in reducing metatarsal peak pressure and pressure time integral. We performed eight DP and eight PD second metatarsal osteotomies on eight pairs of cadaveric feet. A custom designed robotic gait simulator (RGS) generated dynamic in vitro simulations of gait. Second metatarsals were incrementally shortened, with three trials for each length. We calculated regression lines for peak pressure and pressure time integral vs. metatarsal shortening. Shortening the second metatarsal using either osteotomy significantly affected the metatarsal peak pressure and pressure time integral (first and third metatarsal increased, p < 0.01 and <0.05; second metatarsal decreased, p < 0.01). Changes in peak pressure (p ¼ 0.0019) and pressure time integral (p ¼ 0.0046) were more sensitive to second metatarsal shortening with the PD osteotomy than the DP osteotomy. The PD osteotomy plane reduces plantar pressure more effectively than the DP osteotomy plane. Keywords: second metatarsal; plantar pressure; metatarsalgia; lesser metatarsal osteotomies; gait simulation Metatarsalgia is defined as pain, often during weight bearing, of the plantar aspect of the foot under and related to the lesser metatarsal heads. Primary metatarsalgia is associated with biomechanical insufficiencies, and secondary metatarsalgia is associated with systemic conditions. 1 Initially, metatarsalgia is managed with rest, stretching exercises, cushioning, plantar callosity shaving, and anti-inflammatory medications, but data confirming their effectiveness is limited.2 If symptoms persist, surgery is employed to correct the alignment of the metatarsals and/or muscle/ligament balance. Numerous surgical treatments are used, each with its benefits and complications.2-6 Surgical treatment redistributes pressure under the metatarsal heads 7 by either dorsally displacing the head or by shortening the length of the metatarsal. 3 The amount of shortening is determined by the surgeon's experience considering the preoperative length of the metatarsals. 4,8 In this study, we compared the effects of two different osteotomy planes and the overall amount of second metatarsal shortening on plantar pressure. Insight into the relationship between osteotomy plane, metatarsal shortening, and plantar pressure contributes to a more effective treatment of metatarsalgia by providing the surgeon with greater knowledge of biomechanical principles that can be used to make intraoperative osteotomy decisions.The oblique distal to proximal (DP) sliding osteotomy and the oblique proximal to distal (PD) sliding osteotomy are designed to reduce sec...

Lower limb cadaveric robotic gait simulators have been employed to model foot bone kinematics during the stance phase of gait. Often the simulations are performed at reduced body weight (BW) but the effect of this limitation on foot bone kinematics has not been quantified. In this study we utilized the robotic gait simulator (RGS) to measure in vitro foot bone kinematics at different applied ground reaction forces (GRFs) (50% BW and 75% BW). The RGS simulated gait by replicating in vivo tibial kinematics, GRFs, and tendon forces. A six-camera motion analysis system recorded the in vitro motion of ten bones in the foot. Linear mixed effects regression was used to test for differences in range of motion (ROM) by BW (75% vs. 50%) for 12 bone-to-bone relationships. Statistically significantly (p < 0.05) differences in ROM by BW were found for six of the 12 angles investigated. On average the ROM for the 75% BW simulations were systematically higher than that for the 50% BW simulations (p < .0001), but the magnitude of the difference was small (1.2˚). These results indicate that reduced BW in vitro simulations approximately model the ROM and temporal characteristic of foot bone kinematics.

Persons with ankle osteoarthritis (AOA) often seek surgical intervention to alleviate pain and restore function; however, recent research has yielded no superior choice between the two primary options: fusion and replacement. One factor yet to be considered is the effect of footwear on biomechanical outcomes. Comparisons of AOA biomechanics to a normative population are also sparse. The objectives of this study were to (1) determine how footwear uniquely affected gait in persons with ankle fusion and replacement and (2) provide context for AOA biomechanics via comparisons to a healthy adult sample. Thirty-four persons with AOA performed overground walking trials barefoot and shod before surgical intervention and then received either an ankle fusion (n = 14) or replacement (n = 20). Two and/or three years post-surgery, patients returned for gait analysis. Nineteen controls performed the same gait procedures during a single study visit. Spatiotemporal variables and peak angles, internal moments, powers, and forces were calculated to quantify gait behavior. Overall, the two surgical groups performed similarly to each other but demonstrated marked differences from controls both pre-and post-surgery. No significant differences were detected when examining the effect of footwear. The motion of the midfoot with respect to the hindfoot and forefoot may be instrumental in gait biomechanics following an ankle fusion or replacement and should be considered in future investigations.