Kan Imai

Load Response of the Tarsal Bones in Patients with Flatfoot Deformity: In Vivo 3D Study

Background: The objective of this study was to evaluate the bone rotation of each joint in the hindfoot and compare the load response in healthy feet with that in flatfeet by analyzing the reconstructive three-dimensional (3D) CT image data during weightbearing. Methods: CT scans of 21 healthy feet and 21 feet with flatfoot deformity were taken in non-load condition followed by full-body weightbearing load condition. The images of the hindfoot bones were reconstructed into 3D models. The volume merge method in three planes was used to calculate the position of the talus relative to the tibia in the tibiotalar joint, the navicular relative to the talus in talonavicular joint, and the calcaneus relative to the talus in the talocalcaneal joint. Results: The talar position difference to the load response relative to the tibia in the tibiotalar joint in a flatfoot was 1.7 degrees more plantarflexed in comparison to that in a healthy foot (p = 0.031). The navicular position difference to the load response relative to the talus in the talonavicular joint was 2.3 degrees more everted (p = 0.0034). The calcaneal position difference to the load response relative to the talus in the talocalcaneal joint was 1.1 degrees more dorsiflexed (p = 0.0060) and 1.7 degrees more everted (p = 0.0018). Conclusion: Referring to previous cadaver study, regarding not only the cadaveric foot, but also the live foot, joint instability occurred in the hindfoot with load in patients with flatfoot. Clinical Relevance: The method used in this study might be applied to clinical analysis of foot diseases such as the staging of flatfoot and to biomechanical analysis to evaluate the effects of foot surgery in the future. Level of Evidence: III

In Vivo Three-Dimensional Analysis of Hindfoot Kinematics:

Background: Knowledge of normal bone motion of the foot is important for understanding the gait as well as for various pathologies; however, the pattern of 3D motion is not completely understood. The aim of this study was to quantify the in vivo motion of the tibiotalar joint, talocalcaneal joint, and talonavicular joint in normal adult feet using a noninvasive (e.g., nonsurgical) measurement technique. Materials and Methods: CT images were taken of both feet of ten normal young adults (six males, four females) in neutral, plantarflexion, and dorsiflexion positions of the ankle joint, from which 3D virtual models were made of each mid-hind foot bones. The 3D bone motion of these models was calculated using volume merge methods in three major planes. These data were used to analyze the relationship between the motion of the ankle joint and each other joint. Results: Tibiotalar rotation was observed in dorsiflexion, abduction, and eversion during maximal dorsiflexion of the ankle joint. Talocalcaneal and talonavicular rotation was very small because the ankle joint motion was limited to the sagittal plane. Tibiotalar rotation was also observed in plantarflexion and adduction during maximal plantarflexion of the ankle joint, and talocalcaneal rotation was very small. Talonavicular rotation was observed in plantarflexion and inversion. The motion of the x-axis and the z-axis of tibiotalar joint, and the x-axis and the y-axis of the talonavicular and talocalcaneal joint were associated with the ankle motion. Conclusion: Bone motion could be easily and accurately calculated using volume merge methods more effectively than it could with other methods. Clinical Relevance: The data elucidates the baseline segmental motion for comparison with symptomatic subjects which could help us to better understand pathokinematics of various foot and ankle pathologies.

Load response of the medial longitudinal arch in patients with flatfoot deformity: in vivo 3D study.

BACKGROUND The acquisition of flatfoot by an adult is thought to primarily be caused by posterior tibial tendon dysfunction, although some other causes, such as congenital flexible flatfoot or an accessory navicular, may also be responsible. The objective of this study was to evaluate the bone rotation of each joint in the medial longitudinal arch (MLA) and compare the response in healthy feet with that in flat feet by analyzing the reconstructive three-dimensional (3D) CT image data during weightbearing. METHODS CT scans of 20 healthy feet and 24 feet with flatfoot deformity were taken in non-load condition followed by full-body weightbearing condition. Images of the tibia and MLA bones (first metatarsal bone, cuneiforms, navicular, talus, and calcaneus) were reconstructed into 3D models. The volume merge method in three planes was used to calculate the bone-to-bone relative rotations. FINDINGS Under loading conditions, the flatfoot dorsiflexed more in the first tarsometatarsal joint, and everted more in the talonavicular and talocalcaneal joints compared with the healthy foot. The total relative rotation was larger in the flatfoot compared with the healthy foot only in the first tarsometatarsal joint. INTERPRETATION Supporting the MLA in the sagittal direction and the subtalar joint in the coronal direction may be useful for treating flatfoot deformity. The first tarsometatarsal joint may play an important role in diagnosing or treating flatfoot deformity.

Three-dimensional morphology and kinematics of the craniovertebral junction in rheumatoid arthritis.

Study Design. A case-series study. Objectives. To measure the 3-dimensional (3D) morphology and kinematics of the craniovertebral junction (CVJ) using a 3D computed tomography (CT) model; to reveal abnormal patterns and the relationships between pathology and kinematics. Summary of Background Data. Evaluations using radiography, 2-dimensional (2D) CT and magnetic resonance imaging have limitations because of the complex 3D structure of the CVJ. Methods. Twenty-four rheumatoid arthritis patients (21 females, 3 males) with cervical involvement underwent CT scanning of the cervical spine from the basilar process of the occipital bone to the first thoracic vertebra in neutral and flexed positions. The 3D morphology of the occipital condyle, atlas, and axis were classified based on the type of deformity observed. Periodontoid lesions (continuous bony lesions between the atlas and the odontoid process) were also noted. The 3D kinematics in the atlanto-occipital and atlantoaxial joints were evaluated using the volume merge method. Results. Deformities in the atlanto-occipital joints appeared more frequently than those in the atlantoaxial joints. The most common instability pattern was flexural rotation during flexion at the CVJ. The direction of translational motions during flexion was posterior in the atlanto-occipital joint and anterior and caudal in the atlantoaxial joint. Conclusion. The results suggest that bilateral occipital condyle deformation, unilateral and bilateral mass collapse, and periodontoid lesions may affect flexion/extension rotational instability in the atlantoaxial joint. In addition, unilateral occipital condyle deformation and atlantoaxial joint stability may affect sagittal translational instability to the posterior side in the atlanto-occipital joint. The noninvasive 3D CT imaging technique employed here would be useful for predicting the prognosis of patients with rheumatoid deformities at the CVJ.

Bone mass increase specific to the female in a line of transgenic mice overexpressing human osteoblast stimulating factor-1

We have reported that transgenic mice overexpressing human osteoblast stimulating factor-1 (osf1) under the control of the human osteocalcin promoter have a significantly higher bone mineral content and density than nontransgenic littermates. Consequently, bone mass loss due to estrogen deficiency was compensated for in ovariectomized female mice. Here, we show that in this transgenic line, the bone mass increase was evident in female, but not male, mice, as evaluated using the ash assay, double-emission X-ray analysis, and calcein double-labeling to determine the bone formation rate. To elucidate a possible influence on gene expression, we analyzed genomic structures of the inserted transgene and its flanking regions in mouse chromosomes. The results revealed that the transgene was integrated in the mouse repetitive sequences, 234-bp-long Γ-satellite repeats, as inverted multiple (5 + 8) copies. Twelve copies at most seemed to be functional, but no direct evidence supporting female-specific mRNA synthesis of the transgene was obtained.

Weight-bearing three-dimensional computed tomography analysis of the forefoot in patients with flatfoot deformity

BACKGROUND The recent classifications for posterior tibial tendon dysfunction (PTTD) stage II are based on forefoot deformity, but there is still no consensus regarding a detailed explanation of the clinical condition. The purposes of this study were to clarify the clinical condition of flatfoot deformity using three-dimensional (3D) computed tomography (CT) imaging under loading on both healthy and flat feet and to compare 3D movement of the forefoot in response to load. METHODS Ten volunteers and 10 PTTD stage II patients with symptomatic flatfoot deformity were examined. CT scans of 20 healthy and 20 flat feet were performed under non-loading and full weight-bearing conditions. Images of the tibia and foot arch bones (talus, calcaneus, navicular, and first and fifth metatarsal bones) were reconstructed into 3D models. Rotations of individual tarsal bone or metatarsal bone were described by the Eulerian angles. RESULTS Compared with healthy feet, flat feet experienced plantarflexion of the fifth metatarsal bone relative to the first metatarsal bone under loading conditions. We defined this phenomenon as synonymous with forefoot varus on the coronal plane. CONCLUSIONS The results of this study have clarified part of the clinical condition of the forefoot in flatfoot deformity and may have applications in basic research of the staging advancement and substage classification of PTTD.

Effect of therapeutic insoles on the medial longitudinal arch in patients with flatfoot deformity: a three-dimensional loading computed tomography study.

BACKGROUND Insoles are frequently used in orthotic therapy as the standard conservative treatment for symptomatic flatfoot deformity to rebuild the arch and stabilize the foot. However, the effectiveness of therapeutic insoles remains unclear. In this study, we assessed the effectiveness of therapeutic insoles for flatfoot deformity using subject-based three-dimensional (3D) computed tomography (CT) models by evaluating the load responses of the bones in the medial longitudinal arch in vivo in 3D. METHODS We studied eight individuals (16 feet) with mild flatfoot deformity. CT scans were performed on both feet under non-loaded and full-body-loaded conditions, first with accessory insoles and then with therapeutic insoles under the same conditions. Three-dimensional CT models were constructed for the tibia and the tarsal and metatarsal bones of the medial longitudinal arch (i.e., first metatarsal bone, cuneiforms, navicular, talus, and calcaneus). The rotational angles between the tarsal bones were calculated under loading with accessory insoles or therapeutic insoles and compared. FINDINGS Compared with the accessory insoles, the therapeutic insoles significantly suppressed the eversion of the talocalcaneal joint. INTERPRETATION This is the first study to precisely verify the usefulness of therapeutic insoles (arch support and inner wedges) in vivo.

Features of hindfoot 3D kinetics in flat foot in ankle-joint maximal dorsiflexion and plantarflexion

BackgroundIt is difficult to evaluate the kinematics of flat foot from 2D images, and no definitive methods have so far been established to diagnose flat foot. This study evaluated hindfoot kinetics through the progression of posterior tibial tendon dysfunction (PTTD) in patients with stages II and III PTTD flat foot compared with those in normal patients under dorsiflexion and plantarflexion conditions using 3D computed tomography (CT) reconstruction images.MaterialsCT images were taken of 26 normal and 32 flat feet in neutral, plantarflexion, and dorsiflexion positions of the ankle joint, from which 3D virtual models were made of each hindfoot bone. The 3D bone motion of these models was calculated using volume merge methods in three major planes.ResultsTibiotalar-joint motion in ankle-joint plantarflexion became less plantarflexed (normal −41.2°, stage II −33.5°, stage III −25.3°) and less adducted (normal −13.9°, stage II −10.7°, stage III −5.6°) as the stage progressed. Talocalcaneal-joint motion in stage III became more plantarflexed (normal −0.8°, stage II −3.0°, stage III −8.7°) and more adducted (normal −0.3°, stage II −4.7°, stage III −10.3°) as the stage progressed. Talonavicular-joint motion in stage III became more plantarflexed (normal −7.2°, stage II −7.6°, stage III −14.9°) and more adducted (normal 1.0°, stage II −7.3°, stage III −17.9°) as the stage progressed.ConclusionsTibiotalar-joint plantarflexion decreased and talocalcaneal and talonavicular-joint adduction increased in the maximal ankle-joint plantarflexion in stage II in comparison with normal cases. Tibiotalar-joint plantarflexion and adduction were decreased and of the talocalcaneal and talonavicular joints increased in stage III in comparison with stage II cases.

A finite element model of flatfoot (Pes Planus) for improving surgical plan.

Flatfoot is a foot condition caused by the collapse of the medial arch of the foot, and it can result in problems such as severe pain, swelling, abnormal gait, and difficulty walking. Despite being a very common foot deformity, flatfoot is one of the least understood orthopaedic problems, and the opinions regarding its optimal treatment vary widely. In this paper, an FE model of a flatfoot is proposed that is based on CT measurements. Surface meshes of the bones and soft tissue were generated from CT images and then simplified to reduce the node density. A total of 62 ligaments, 9 tendons, and the plantar fascia were modeled manually. Volume meshes of the different components were generated and combined to form the completed flatfoot model. A dynamic FE formulation was derived, and a balanced standing simulation was performed. The model was validated by comparing stress distribution results from the simulation to experimental data.

Tarsal Tunnel Syndrome in Hemodialysis Patients A Case Series

Background: The purpose of our study was to investigate tarsal tunnel syndrome (TTS) arising in patients who have undergone maintenance dialysis at our facility and to evaluate the frequency, pathological characteristics, and diagnosis of TTS. Methods: We evaluated 1011 patients (mean age 65.1 years) undergoing maintenance dialysis from 2000 to 2006 at our hospital. In patients diagnosed with TTS, we examined clinical symptoms and imaging findings. In addition, we evaluated intraoperative findings in patients who had undergone surgery. A follow-up study was conducted for at least 1 year. Results: Five patients (7 ankles) (mean age 57.8 years) were diagnosed as have TTS, with a mean dialysis duration of 23.4 years (range, 7-30 years). With conservative treatment consisting of rest and a steroid injection, 4 ankles showed improvement. Surgery was performed on 3 ankles. Amyloidoma, nodular tumor fragile deposits in the soft tissue or thecal surface, proliferation of the synovial tendon sheath, and thickened joint capsule were recognized in 3 ankles, and a concomitant ganglion was recognized in 1 ankle. Histologically, the deposition of hyaline material was recognized in all tissues, including the walls of the ganglion or joint capsule, by staining to a pale red color using Congo red stain. An immunohistochemical study indicated positive staining by β-2 microglobulin staining. The flexor retinaculum was thin in all cases, with retinaculum-like thickness not found in carpal tunnel syndrome. Conclusions: We believe that the occurrence of TTS in dialysis patients was 0.5%, with a tendency to be more prevalent among patients undergoing maintenance dialysis for 5 or more years. The pathological process of TTS may be different from that of carpal tunnel syndrome. Level of Evidence: Level IV, retrospective case series.