This study estimated the contribution of the midfoot joint complex (MJC) kinematics to the pelvis anterior-posterior positions during the stance phase of walking and investigated whether the MJC is functionally coordinated with the lower limb joints to maintain similar pelvic positions across steps. Hip, knee, ankle, and MJC sagittal angles were measured in 11 nondisabled participants during walking. The joints\' contributions to pelvic positions were computed through equations derived from a link-segment model. Functional coordination across steps was identified when the MJC contribution to pelvic position varied and the summed contributions of other joints varied in the opposite direction (strong negative covariations [r ≤ -.7] in stance phase instants). We observed that the MJC plantarflexion (arch raising) during the midstance and late stance leads the pelvis backward, avoiding excessive forward displacement. The MJC was the second joint that contributed most to the pelvis positions (around 18% of all joints\' contributions), after the ankle joint. The MJC and ankle were the joints that were most frequently coordinated with the other joints (≅70% of the stance phase duration). The findings suggest that the MJC is part of the kinematic chain that determines pelvis positions during walking and is functionally coordinated with the lower limb joints.

BACKGROUND: The purpose of this study was to evaluate the prevalence of foot involvement in psoriatic arthritis and to describe its different clinical and radiological features.
METHODS: We conducted a cross sectional study including 40 patients with psoriatic arthritis over a period of 12 months. Anamnesis, clinical examination of feet, podoscopic examination, X-rays of feet and heels, and ultrasound in B mode and power Doppler mode were done for each patient.
RESULTS: Foot involvement was found in 95% of cases. It was symptomatic in 70% and inaugural of the disease in 20% of cases. The hindfoot and the forefoot were the sites most affected (77.5% and 47.5% respectively). The involvement of the midfoot was rarer (25%). Dactylitis was found in 17.5% and deformities of forefoot were found in 22.5% of cases. Antalgic gait was noted in 17.5% and static disorders of foot at podoscopic examination were identified in 35% of cases. Feet dermatological manifestations were found in 45% of cases. Diagnosis of different rheumatological manifestations was based on clinical findings and caracteristic radiological images on X-rays. We demonstrate he sensitivity of ultrasound in the detection and the diagnosis of different foot lesions including enthesitis, synovitis and tenosynovitis, dactylitis, bone erosions and psoriatic nail dystrophy.

The role of the many small foot articulations and plantar tissues in gait is not well understood. While kinematic multi-segment foot models have increased our knowledge of foot segmental motions, the integration of kinetics with these models could further advance our understanding of foot mechanics and energetics. However, capturing and effectively utilizing segmental ground reaction forces remains challenging. The purposes of this study were to (1) develop methodology to integrate plantar pressures and shear stresses with a multi-segment foot model, and (2) generate and concisely display key normative data from this combined system. Twenty-six young healthy adults walked barefoot (1.3 m/s) across a pressure/shear sensor with markers matching a published 4-segment foot model. A novel anatomical/geometric template-based masking method was developed that successfully separated regions aligned with model segmentation. Directional shear force plots were created to summarize complex plantar shear distributions, showing opposing shear forces both between and within segments. Segment centers of pressure (CoPs) were shown to be primarily stationary within each segment, suggesting that forward progression in healthy gait arises primarily from redistributing weight across relatively fixed contact points as opposed to CoP movement within a segment. Inverse dynamics-based normative foot joint moments and power were presented in the context of these CoPs to aid in interpretation of tissue stresses. Overall, this work represents a successful integration of motion capture with direct plantar pressure and shear measurements for multi-segment foot kinetics. The presented tools are versatile enough to be used with other models and contexts, while the presented normative database may be useful as a baseline comparison for clinical work in gait energetics and efficiency, balance, and motor control. We hope that this work will aid in the advancement and availability of kinetic MSF modeling, increase our knowledge of foot mechanics, and eventually lead to improved clinical diagnosis, rehabilitation, and treatment.

Time spent in the operating room is valuable to both surgeons and patients. One of the biggest rate-limiting factors when it comes to arthrodesis procedures of the foot and ankle is cartilage removal and joint preparation. Power instrumentation in joint preparation provides an avenue to decrease joint preparation time, thus decreasing operating room time and costs. Arthrodesis of 47 joints (n) from 27 patients were included. Power rasp joint preparation in 26 joints was compared to traditional osteotome and curette joint preparation in 21 joints in both time (seconds), cost (total operating room time cost per minute), and union rate. The overall mean joint preparation time using power rasp for the subtalar joint was 268.3 seconds, talonavicular joint 212.3 seconds, calcaneocuboid joint 142.6 seconds, 1st TMT 107.2 seconds. Mean joint preparation time using traditional method for subtalar joint 509.8 seconds, talonavicular joint 393.0 seconds, calcaneocuboid joint 400.0 seconds, 1st TMT 319.6 seconds. Mean cost of joint preparation using power rasp for subtalar joint $165.47, talonavicular joint $130.89, calcaneocuboid joint $87.94, 1st TMT $66.11. Mean cost of joint preparation using traditional techniques for subtalar joint $314.34, talonavicular joint $242.35, calcaneocuboid joint $246.67, 1st TMT $197.33. Overall union rate was 98% (1 asymptomatic non-union). Increasing efficiency in the operating room is vital to every surgeon\'s practice. Power rasp joint preparation is a viable option to increase efficiency and decrease operative time, this study shows no statistically significant differences in union rate, with comparable rates to existing literature.