Locally obtained autologous bone grafts are effective for achieving arthrodesis while managing foot and ankle charcot's neuroarthropathy: short to mid-term results from a specialized north African foot and ankle surgery unit.

PURPOSE: We aimed to report the union rate after only utilizing a locally obtained autologous bone graft while correcting the deformity and performing joint arthrodesis in patients with foot and ankle Charcot neuropathy (CN) and to report on the radiographic, functional, complications incidence outcomes at a minimum of two years of follow up. METHODS: We included 24 patients having a mean age of 55.4 ± 10.1 years diagnosed with CN of the foot, ankle, or both. Seven (29.2%) cases were classified as Brodsky type 1, 11 (45.8%) as type 3 A, and six (25%) were type 4. Hindfoot and Midfoot bi-columnar arthrodesis was performed in 70.8% and 29.2% of the patients, respectively. Eight (33.3%) cases had preoperative ulcers. Functional outcomes were evaluated using a modified AOFAS score. Arthrodesis site union was assessed clinically and radiographically. All patients were available for a mean follow up of 35.7 ± 9.5 (24-54) months. RESULTS: Arthrodesis site union was achieved in 23 (95.8%) cases after a mean of 4 ± 1.7 (2-7.5) months. The mean modified AOFAS score was 72.4 ± 10.41 (46-83) points; 79.2% achieved excellent and good scores. Ulcers healed in 87.5% of the patients. Twenty-two (91.7%) patients were satisfied with their functional results. Infection incidence was 12.5%, and no patients required revision or amputation. CONCLUSION: Foot and ankle Charcot neuroarthropathy deformity correction by arthrodesis of the affected joint as a salvage management option resulted in acceptable clinical and radiological outcomes. To enhance the local environment for arthrodesis consolidation, locally obtained autografts led to higher union rates and avoided the drawbacks of using other graft types.

Understanding the design differences between multisegmented foot models and their impact on joint kinetic outcomes.

Multisegmented foot models (MSFMs) are used to capture data of specific regions of the foot instead of representing the foot as a single, rigid segment. It has been documented that different MSFMs do not yield the same joint kinematic data, but there is little information available regarding their use for kinetic analysis. We compared the moment and power at the tibiotalar, midtarsal, and metatarsophalangeal joints of four MSFMs using motion capture data of young adult runners during stance phase of barefoot walking and jogging. Of these models, three were previously validated: the Oxford, Milwaukee, and Ghent Foot Models. One model was developed based upon literature review of existing models: the "Vogel" model. We performed statistical parametric mapping comparing joint measurements from each model to the corresponding results from the Oxford model, the most heavily studied MSFM. We found that the Oxford, Milwaukee, Vogel, and Ghent Foot Models do not provide the same kinetic results. The differences in segment definitions impact the degrees of freedom in a manner that alters the measured kinematic function of the foot, which in turn impacts the kinetic results. The results of this study capture the variability in performance of MSFMs as it relates to kinetic outcomes and emphasize a need to remain aware of model differences when interpreting results.

Joint synergy and muscle activity in the motion of the ankle-foot complex.

The movement of the ankle-foot complex joints is coupled as a result of various physiological and physical constraints. This study introduces a novel approach to the analysis of joint synergies and their physiological basis by focusing on joint rotational directions and the types of muscle contractions. We developed a biomimetic model of the ankle-foot complex with seven degrees of freedom, considering the skeletal configuration and physiological axis directions. Motion capture experiments were conducted with eight participants performing dorsiflexion and plantarflexion in open-chain states, as well as various walking tasks in closed-chain states, across different ground inclinations (±10, ±5, 0 deg) and walking speeds (3 and 4 km h-1). Hierarchical cluster analysis identified joint synergy clusters and motion primitives, revealing that in open-chain movements, plantarflexion of the ankle, tarsometatarsal and metatarsophalangeal joints exhibited synergy with the inversion of the remaining joints in the complex; meanwhile, dorsiflexion was aligned with eversion. During closed-chain movements, the synergies grouping was exchanged in the subtalar, talonavicular and metatarsophalangeal joints. Further analysis showed that in open-chain movements, synergy patterns influenced by multi-joint muscles crossing oblique joint axes contribute to foot motion. In closed-chain movements, these changes in synergistic patterns enhance the propulsion of the center of mass towards the contralateral leg and improve foot arch compliance, facilitating human motion. Our work enhances the understanding of the physiological mechanisms underlying synergistic motion within the ankle-foot complex.

Cone-beam computed tomography imaging and three-dimensional analysis of midfoot joints during non-weightbearing and weightbearing in 11 healthy feet.

BACKGROUND: Studies report that Lisfranc injury is more common than thought. Several imaging methods for assessing the stability of Lisfranc injury have been described but many are impossible to standardize and not accurate enough. PURPOSE: To present a three-dimensional (3D) method for analyzing the changes in the joint space width of the midfoot joint and the joints of the medial part of the Lisfranc complex in healthy individuals. MATERIAL AND METHODS: Non-weightbearing and weightbearing cone-beam computed tomography (CBCT) images of 11 healthy feet were acquired and analyzed with 3D software. The mean range of joint space width changes of each joint was computed from the changes in individual image pairs. RESULTS: 3D analysis software was used to analyze the medial part of the Lisfranc complex. In this sample of healthy feet, the changes in the joint spaces in the medial part of Lisfranc complex, calculated with 3D analysis software, was less than 0.6 mm. The distance between bones increased or decreased, depending on which part of the joint surface the measurements were taken. CONCLUSION: In this study, we present a 3D analysis method to evaluate midfoot joint space width changes. Our analysis revealed that in healthy feet there are only minimal changes in the joint space width between weightbearing and non-weightbearing indicating minimal movement of the midtarsal joints. The 3D analysis of weightbearing CBCT data provides a promising tool for analyzing the small midfoot joints in a variety of conditions.

Relationship between joint structure of the first tarsometatarsal joint and its degeneration.

This study aimed to elucidate the relationship between joint structures of the first tarsometatarsal and articular facet degeneration. A total of 100 feet from 50 cadavers were examined. The articular facets of the first metatarsal and medial cuneiform were categorized into four types based on the superior and inferior facets' separation, and the formation of the inferior lateral facet on the lateral plantar prominence: Type I, a single facet with no separation or inferior lateral facet; Type II-a, two facets with separation but no inferior lateral facet; Type II-b, two facets, no separation, but with an inferior lateral facet; Type III, three facets with separation and an inferior lateral facet. When both bone types matched, they were defined as Type I, Type II-a, Type II-b, and Type III joints, respectively; unmatched types were classified as Unpair joints. The severity of articular cartilage degeneration on both bones was assessed using a 5-point scale. The degeneration grade was compared among joint types. Type III joints exhibited significantly milder articular cartilage degeneration in medial cuneiform compared to Type II-a, II-b, Unpair joints. The formation of inferior lateral facet and separation of the superior and inferior facets might be crucial for the joint's stability.

Risk Factors for Midfoot Arthritis Associated With Medical History by Weight Bearing Computed Tomography.

Tarso-metatarsal joints and naviculocuneiform joints comprising midfoot is the second most commonly involved joints following the first metatarsophalangeal joint in the foot. However, related factors of midfoot arthritis (MA) have been rarely reported. The bony structure and alignment can be more precisely assessed using Weight-Bearing Computed Tomography (WBCT) than conventional radiographs. Therefore, the aim of this study was to investigate risk factors for MA related to medical history and comorbid foot deformities using WBCT. WBCT data from September 2014 to April 2022 were extracted from a single referral hospital. All cases were divided into two groups by the presence of MA. Twenty-five potential related factors including demographics, etiology, and common co-occurring foot deformities were collected for comparison. Six hundred six cases (247 males and 359 females) among consecutive 1316 cases between September 2014 to April 2022 were selected. One hundred thirty-nine male cases (56.3%) and 210 female cases (58.5%) showed MA. In stepwise multiple logistic regression analysis, 5 factors remained statistically significant. The multivariate-adjusted odds ratios for age, laterality, body mass index (BMI), Progressive Collapsing Foot Deformity (PCFD), and lesser toe deformities (LTD) were 1.08, 1.54, 1.05, 6.62, and 3.03 respectively. Risk factors for MA associated with medical history and foot deformities included age, laterality, BMI, PCFD, and LDT.

The Midfoot Joint Complex (Foot Arch) Contributes to the Upper Body Position in Bipedal Walking and Coordinates With the Lower Limb Joints.

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.

Multi-segment foot kinematics during gait in children with spastic cerebral palsy.

BACKGROUND: Foot deformities (e.g. planovalgus and cavovarus) are very common in children with spastic cerebral palsy (CP), with the midfoot often being involved. Dynamic foot function can be assessed with 3D gait analysis including a multi-segment foot model. Incorporating a midfoot segment in such a model, allows quantification of separate Chopart and Lisfranc joint kinematics. Yet, midfoot kinematics have not previously been reported in CP. RESEARCH QUESTIONS: What is the difference in multi-segment kinematics including midfoot joints between common foot deformities in CP and typically-developing feet? METHODS: 103 feet of 57 children with spastic CP and related conditions were retrospectively included and compared with 15 typically-developing children. All children underwent clinical gait analysis with the Amsterdam Foot Model marker set. Multi-segment foot kinematics were calculated for three strides per foot and averaged. A k-means cluster analysis was performed to identify foot deformity groups that were present within CP data. The deformity type represented by each cluster was based on the foot posture index. Kinematic output of the clusters was compared to typically-developing data for a static standing trial and for the range of motion and kinematic waveforms during walking, using regular and SPM independent t-tests respectively. RESULTS: A neutral, planovalgus and varus cluster were identified. Neutral feet showed mostly similar kinematics as typically-developing data. Planovalgus feet showed increased ankle valgus and Chopart dorsiflexion, eversion and abduction. Varus feet showed increased ankle varus and Chopart inversion and adduction. SIGNIFICANCE: This study is the first to describe Chopart and Lisfranc joint kinematics in different foot deformities of children with CP. It shows that adding a midfoot segment can provide additional clinical and kinematic information. It highlights joint angles that are more distinctive between deformities, which could be helpful to optimize the use of multi-segment foot kinematics in the clinical decision making process.

New Perspectives on Foot Segment Forces and Joint Kinetics-Integrating Plantar Shear Stresses and Pressures with Multi-segment Foot Modeling.

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.

Operative Time, Cost, and Union Rate of Power Rasp Joint Preparation Versus Traditional Preparation in Arthrodesis of the Foot and Rearfoot.

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.

Foot involvement in psoriatic arthritis: Prevalence, clinical and radiological features.

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. PATIENTS AND 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.

Nonunion Rate Following Primary Arthrodesis for Acute Lisfranc Injuries.

Injury to the tarsometatarsal joint (TMT) results in instability throughout the midfoot that does not often improve with conservative management. If instability is identified, surgical intervention is frequently recommended, either open reduction and internal fixation (ORIF) or primary arthrodesis (PA). These 2 treatment options have been compared in the literature multiple times, often reporting similar outcomes. Due to this, as well as the need for subsequent hardware removal after ORIF has led many surgeons towards PA at the index surgery. Concern for nonunion is a leading concern with surgeons who advocate instead for ORIF. The purpose of this study is to review patients who underwent PA and observe nonunion rates. Nonunion at the TMT has been previously studied, but only in the chronic setting. We performed a retrospective study of 34 patients who had PA in the management of an acute Lisfranc injury. The average age in our study was 43.9 years old (range 19-72, SD 17.4) with an average follow-up of 9.4 months (range 4-33, SD 6.2). Radiographs were evaluated for signs of nonunion at regular postoperative intervals. Within the patients included in the study, a total of 71 TMT joints were fused. Overall successful fusion rate was 95.8% at an average of 7.9 weeks (range 6-12, SD 1.4) postoperatively. Individual nonunion rates at the first, second, and third TMT were 0%, 1.4% and 2.8% respectively. Our study demonstrates that primary arthrodesis provides a predictable outcome with low nonunion rates in the management of acute Lisfranc injury.

Mechanics of the foot and ankle joints during running using a multi-segment foot model compared with a single-segment model.

The primary purpose of this study was to compare the ankle joint mechanics, during the stance phase of running, computed with a multi-segment foot model (MULTI; three segments) with a traditional single segment foot model (SINGLE). Traditional ankle joint models define all bones between the ankle and metatarsophalangeal joints as a single rigid segment (SINGLE). However, this contrasts with the more complex structure and mobility of the human foot, recent studies of walking using more multiple-segment models of the human foot have highlighted the errors arising in ankle kinematics and kinetics by using an oversimplified model of the foot. This study sought to compare whether ankle joint kinematics and kinetics during running are similar when using a single segment foot model (SINGLE) and a multi-segment foot model (MULTI). Seven participants ran at 3.1 m/s while the positions of markers on the shank and foot were tracked and ground reaction forces were measured. Ankle joint kinematics, resultant joint moments, joint work, and instantaneous joint power were determined using both the SINGLE and MULTI models. Differences between the two models across the entire stance phase were tested using statistical parametric mapping. During the stance phase, MULTI produced ankle joint angles that were typically closer to neutral and angular velocities that were reduced compared with SINGLE. Instantaneous joint power (p<0.001) and joint work (p<0.001) during late stance were also reduced in MULTI compared with SINGLE demonstrating the importance of foot model topology in analyses of the ankle joint during running. This study has highlighted that considering the foot as a rigid segment from ankle to MTP joint produces poor estimates of the ankle joint kinematics and kinetics, which has important implications for understanding the role of the ankle joint in running.

Structural Foot Characteristics in People With Midfoot Osteoarthritis: Cross-Sectional Findings From the Clinical Assessment Study of the Foot.

OBJECTIVE: This study compared radiographic measures of foot structure between people with and without symptomatic radiographic midfoot osteoarthritis (OA). METHODS: This was a cross-sectional study of adults aged 50 years and older registered with four UK general practices who reported foot pain in the past year. Bilateral weightbearing dorsoplantar and lateral radiographs were obtained. Symptomatic radiographic midfoot OA was defined as midfoot pain in the last 4 weeks, combined with radiographic OA in one or more midfoot joints (first cuneometatarsal, second cuneometatarsal, navicular-first cuneiform, and talonavicular). Midfoot OA cases were matched 1:1 for sex and age to controls with a 5-year age tolerance. Eleven radiographic measures were extracted and compared between the groups using independent sample t-tests and effect sizes (Cohen's d). RESULTS: We identified 63 midfoot OA cases (mean ± SD age was 66.8 ± 8.0 years, with 32 male and 31 female participants) and matched these to 63 controls (mean ± SD age was 65.9 ± 7.8 years). There were no differences in metatarsal lengths between the groups. However, those with midfoot OA had a higher calcaneal-first metatarsal angle (d = 0.43, small effect size, P = 0.018) and lower calcaneal inclination angle (d = 0.46, small effect size, P = 0.011) compared with controls. CONCLUSIONS: People with midfoot OA have a flatter foot posture compared with controls. Although caution is required when inferring causation from cross-sectional data, these findings are consistent with a pathomechanical pathway linking foot structure to the development of midfoot OA. Prospective studies are required to determine the temporal relationships between foot structure, function, and the development of this common and disabling condition.

Relationship between arthritis of the second and third tarsometatarsal joints and incongruity of the first tarsometatarsal joint in patients with hallux valgus.

OBJECTIVES: Hallux valgus is associated with tarsometatarsal arthritis; its pathophysiology remains unknown. Therefore, we aimed to elucidate the relationship between arthritis of the second and third tarsometatarsal joints and incongruity of the first tarsometatarsal joint in the sagittal plane. METHODS: Forty-three patients (64 feet) with hallux valgus who underwent surgery at University Hospital Kyoto Prefectural University of Medicine were included and divided into two groups: control (without second and third tarsometatarsal joint degeneration) and osteoarthritis (with second and third tarsometatarsal joint degeneration). Intergroup comparisons of the incongruity of the first tarsometatarsal joint in the sagittal plane, age, body mass index, hallux valgus angle, first-second intermetatarsal angle, metatarsus adductus angle, Meary's angle, and calcaneal pitch angle were performed. RESULTS: The proportion of patients with incongruity of the first tarsometatarsal joint was significantly higher in the osteoarthritis group than in the control group. Logistic regression analysis identified incongruity of the first tarsometatarsal joint and metatarsus adductus angle as significant related factors for arthritis of the second and third tarsometatarsal joints. CONCLUSIONS: Incongruity of the first tarsometatarsal joint in the sagittal plane was involved in the development of arthritis of the second and third tarsometatarsal joints in patients with hallux valgus.

Changes in Relative Work of the Lower Extremity and Distal Foot Joints After Total Ankle Replacement: An Exploratory Study.

Ankle osteoarthritis does not only led to lower ankle power generation, but also results in compensatory gait mechanics at the hip and Chopart joints. Much of previous work explored the relative work distribution after total ankle replacement (TAR) either across the lower extremity joints where the foot was modelled as a single rigid unit or across the intrinsic foot joints without considering the more proximal lower limb joints. Therefore, this study aims, for the first time, to combine 3D kinetic lower limb and foot models together to assess changes in the relative joint work distribution across the foot and lower limb joints during level walking before and after patients undergo TAR. We included both patients and healthy control subjects. All patients underwent a three-dimensional gait analysis before and after surgery. Kinetic lower limb and multi-segment foot models were used to quantify all inter-segmental joint works and their relative contributions to the total lower limb work. Patients demonstrated a significant increase in the relative ankle positive joint work contribution and a significant decrease in the relative Chopart positive joint work contribution after TAR. Furthermore, there exists a large effect toward decreases in the relative contribution of the hip negative joint work after TAR. In conclusion, this study seems to corroborate the theoretical rationale that TAR reduces the compensatory strategy in the Chopart and hip joints in patients suffering from end-stage ankle osteoarthritis.

The Posttraumatic Tarsometatarsal Joints.

Tarsometatarsal joint injuries can be painful and debilitating and are most commonly due to direct or indirect trauma. Posttraumatic arthritis is a well-known long-term complication, with incidence as high as 58%. Conservative treatment options include shoe modifications, orthotic inserts, topical or oral anti-inflammatories, and intra-articular corticosteroid injections. There are various joint prep and fixation techniques reported in the literature, many with positive clinical and radiographic outcomes. This article discusses nonoperative and operative management of posttraumatic tarsometatarsal joint arthritis, reviews available literature, and includes the authors' tips and techniques.

Foot Sole Contact Forces vs. Ground Contact Forces to Obtain Foot Joint Moments for In-Shoe Gait-A Preliminary Study.

In-shoe models are required to extend the clinical application of current multisegment kinetic models of the bare foot to study the effect of foot orthoses. Work to date has only addressed marker placement for reliable kinematic analyses. The purpose of this study is to address the difficulties of recording contact forces with available sensors. Ten participants walked 5 times wearing two different types of footwear by stepping on a pressure platform (ground contact forces) while wearing in-shoe pressure sensors (foot sole contact forces). Pressure data were segmented by considering contact cells' anteroposterior location, and were used to compute 3D moments at foot joints. The mean values and 95% confidence intervals were plotted for each device per shoe condition. The peak values and times of forces and moments were computed per participant and trial under each condition, and were compared using mixed-effect tests. Test-retest reliability was analyzed by means of intraclass correlation coefficients. The curve profiles from both devices were similar, with higher joint moments for the instrumented insoles at the metatarsophalangeal joint (~26%), which were lower at the ankle (~8%) and midtarsal (~15%) joints, although the differences were nonsignificant. Not considering frictional forces resulted in ~20% lower peaks at the ankle moments compared to previous studies, which employed force plates. The device affected both shoe conditions in the same way, which suggests the interchangeability of measuring joint moments with one or the other device. This hypothesis was reinforced by the intraclass correlation coefficients, which were higher for the peak values, although only moderate-to-good. In short, both considered alternatives have drawbacks. Only the instrumented in-soles provided direct information about foot contact forces, but it was incomplete (evidenced by the difference in ankle moments between devices). However, recording ground reaction forces offers the advantage of enabling the consideration of contact friction forces (using force plates in series, or combining a pressure platform and a force plate to estimate friction forces and torque), which are less invasive than instrumented insoles (which may affect subjects' gait).

Kinetic coupling in distal foot joints during walking.

BACKGROUND: Kinematic coupling between the first metatarsophalangeal (MTP) and midtarsal joints is evident during gait and other movement tasks, however kinetic foot coupling during walking has not been examined. Furthermore, contributing factors to foot coupling are still unclear. Therefore, the purpose of this study was to investigate kinematic and kinetic coupling within the foot by restricting MTP motion during overground walking. We hypothesized that when the MTP joint was prevented from fully extending, the midtarsal joint would achieve less peak motion and generate less positive work compared to walking with normal MTP motion. METHODS: Twenty-six individuals participated in this randomized cross-over study. Using motion capture to track motion, participants walked at 1.3 m/s while wearing a brace that restricted MTP motion in a neutral (BR_NT) or extended (BR_EX) position. Additionally, participants walked while wearing the brace in a freely moveable setting (BR_UN) and with no brace (CON). A pressure/shear sensing device was used to capture forces under each foot segment. During stance, peak joint motion and work were calculated for the MTP and midtarsal joints using inverse dynamics. A series of ANOVAs and Holm post hoc tests were performed for all metrics (alpha = 0.05). RESULTS: The brace successfully decreased peak MTP motion by 19% compared to BR_UN and CON. This was coupled with 9.8% less midtarsal motion. Kinetically, the work absorbed by the MTP joint (26-51%) and generated by the midtarsal joint (30-38%) were both less in BR_EX and BR_NT compared to BR_UN. CONCLUSION: Implications and sources of coupling between the MTP and midtarsal joints are discussed within the context of center of pressure shifts and changes to segmental foot forces. Our results suggest that interventions aimed at modulating MTP negative work (such as footwear or assistive device design) should not ignore the midtarsal joint.

The Role of First Tarsometatarsal Joint Morphology and Instability in the Etiology of Hallux Valgus: A Case-Control Study.

BACKGROUND: The morphology of foot joints is widely accepted as a significant factor in the development of various foot disorders. Nevertheless, the role of the first tarsometatarsal joint (TMT1) morphology in hallux valgus (HV) remains unclear, and its impact on TMT1 instability has not been fully explored. This study aimed to investigate the TMT1 morphology and its potential correlation with HV and TMT1 instability. METHODS: Weightbearing computed tomography (WBCT) scans of 82 consecutive feet with HV and 79 controls were reviewed in this case-control study. Three-dimensional (3D) models of TMT1 were constructed using Mimics software and WBCT scans. The height of the TMT1 facet (FH) and the superior, middle, and inferior facet width (SFW, MFW, and IFW) were measured on anteroposterior view of the first metatarsal base. On the lateral view, the inferior lateral facet height and angle (ILFH and ILFA) were measured. TMT1 instability was evaluated using the TMT1 angle. RESULTS: Compared with the control group, the HV group had a significantly wider MFW (9.9 mm in HV, 8.7 mm in control), lower ILFH (1.7 mm in HV, 2.5 mm in control), smaller ILFA (16.3 degrees in HV, 24.5 degrees in control), and larger TMT1 angle (1.9 degrees in HV, 0.9 degrees in control) (all P < .05). No significant differences were found between the 2 groups in FH, SFW, and IFW (all P > .05). The study identified 4 types of TMT1 morphology: continuous-flat, separated-flat, continuous-protruded, and separated-protruded. The continuous-flat type possessed significantly larger HVA, IMA, and TMT1 angles compared with other types (all P < .001). CONCLUSION: This study indicates a potential association between TMT1 morphology and the severity of HV and identifies 4 TMT1 types. Notably, the continuous-flat type is found to be associated with more severe HV and TMT1 instability. LEVEL OF EVIDENCE: Level III, retrospective comparative study.