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.

Since there is no statistical evidence showing which failure mode contributes most to revision surgeries, it is concluded that more information/data is needed to further investigate failure modes in ankle arthroplasties. Since the numbers of such surgeries are increasing, sufficient data should become available in time.

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...

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