Case Report: Description of two fractures during the use of a powered exoskeleton.

Introduction: Powered robotic exoskeletons are a promising solution to enable standing and walking in patients with spinal cord injury (SCI). Although training and walking with an exoskeleton in motor complete SCI patients is considered safe, the risks of unexpected (technical) adverse events and the risk of fractures are not fully understood. This article reports the occurrence of two different cases of bone fracture during exoskeleton usage. Furthermore, advice is given for extra safety training and instructions. Case presentation: The first case concerns a 47-year-old woman with T12 AIS A SCI. Her exoskeleton shut down unexpectedly probably causing a misalignment of the joints of her lower extremities relative to the joints of the exoskeleton, which resulted in a fracture of her left tibia. The second case involves a 39-year-old man with L1 AIS B SCI. An unexpected fracture of the right distal tibia occurred without a specific prior (traumatic) incident. Discussion: Exoskeleton training instructors, SCI patients and their buddies should be instructed how to handle emergency situations. Furthermore, they should be aware of the risk of stress fractures of the lower extremities. Proper alignment of the exoskeleton relative to the body is of utmost importance to reduce fracture risk. In the case of swelling and discoloring of the skin, radiographic examination should be performed in order to exclude any fracture.

Operative treatment algorithm for foot deformities in Charcot-Marie-Tooth disease.

The present article presents a short summary concerning the pathomechanisms and clinical presentation of foot deformities in Charcot-Marie-Tooth syndrome. Furthermore, a classification system is introduced and based on a recently performed review of the literature an operative treatment algorithm is provided. The operative technique of the following surgical procedures is described in more detail: 1. dorsiflexion osteotomy at the base of the 1st metatarsus, 2. dorsiflexion osteotomy at the base of a lesser metatarsal bone, 3. claw hallux correction including fusion of the first phalangeal joint, 4. claw toe correction, 5. transfer of extensor digitorum longus tendons to the peroneal tendons and finally 6. tibialis posterior tendon transfer to the dorsiflexors of the foot.

Simple resection arthroplasty for treatment of 4th and 5th tarsometatarsal joint problems. A technical tip and a small case series.

Osteoarthritis, primary or secondary, of the fourth and/or fifth tarsometatarsal (TMT) joint is a rare condition. When conservative treatment fails or proves to be unacceptable for the patient, operative treatment is an option. In this article the technique of resection arthroplasty is described and a retrospective case series of 6 patients is presented. Three patients underwent tendon interposition arthroplasty after resection of the two joints and in the last three cases no interposition at all was performed. Results suggest that resection arthroplasty without interposition may be as effective as other operative treatment options for patients with fourth and fifth TMT pathology.

Foot lengthening and shortening during gait: a parameter to investigate foot function?

INTRODUCTION: Based on the windlass mechanism theory of Hicks, the medial longitudinal arch (MLA) flattens during weight bearing. Simultaneously, foot lengthening is expected. However, changes in foot length during gait and the influence of walking speed has not been investigated yet. METHODS: The foot length and MLA angle of 34 healthy subjects (18 males, 16 females) at 3 velocities (preferred, low (preferred -0.4 m/s) and fast (preferred +0.4 m/s) speed were investigated with a 3D motion analysis system (VICON(®)). The MLA angle was calculated as the angle between the second metatarsal head, the navicular tuberculum and the heel in the local sagittal plane. Foot length was calculated as the distance between the marker at the heel and the 2nd metatarsal head. A General Linear Model for repeated measures was used to indicate significant differences in MLA angle and foot length between different walking speeds. RESULTS: The foot lengthened during the weight acceptance phase of gait and shortened during propulsion. With increased walking speed, the foot elongated less after heel strike and shortened more during push off. The MLA angle and foot length curve were similar, except between 50% and 80% of the stance phase in which the MLA increases whereas the foot length showed a slight decrease. CONCLUSION: Foot length seems to represent the Hicks mechanism in the foot and the ability of the foot to bear weight. At higher speeds, the foot becomes relatively stiffer, presumably to act as a lever arm to provide extra propulsion.

Classification of forefoot pain based on plantar pressure measurements.

BACKGROUND: Plantar pressure is widely used to evaluate foot complaints. However, most plantar pressure studies focus on the symptomatic foot with foot deformities. The purposes of this study were to investigate subjects without clear foot deformities and to identify differences in plantar pressure pattern between subjects with and without forefoot pain. The second aim was to discriminate between subjects with and without forefoot pain based on plantar pressure measurements using neural networks. METHODS: In total, 297 subjects without foot deformities of whom almost 50% had forefoot pain walked barefoot over a pressure plate. Foot complaints and subject characteristics were assessed with a questionnaire and a clinical evaluation. Plantar pressure was analyzed using a recently developed method, which produced pressure images of the time integral, peak pressure, mean pressure, time of activation and deactivation, and total contact time per pixel. After pre-processing the pressure images with principal component analysis, a forward selection procedure with neural networks was used to classify forefoot pain. FINDINGS: The pressure-time integral and mean pressure were significantly larger under the metatarsals II and III for subjects with forefoot pain. A neural network with 14 input parameters correctly classified forefoot pain in 70.4% of the test feet. INTERPRETATION: The differences in plantar pressure parameters between subjects with and without forefoot pain were small. The reasonable performance of forefoot pain classification by neural networks suggests that forefoot pain is related more to the distribution of the pressure under the foot than to the absolute values of the pressure at fixed locations.

Quantitative ultrasound of lower leg and foot muscles: feasibility and reference values.

BACKGROUND: Ultrasound is a non-invasive method to quantitatively measure various muscle parameters. Purpose of this study was to assess the feasibility of ultrasound of lower leg and foot muscles and to obtain reference values for muscle thickness (MT) and echo intensity (EI). METHODS: Ultrasound measurements of leg and foot muscles were performed in 60 healthy adults. MT and EI were quantitatively determined for the abductor hallucis (AH), extensor digitorum brevis (EDB), extensor hallucis longus (EHL) and peroneus longus (PER) muscles. Influence of age, height, weight and sex was determined using a multiple linear regression analysis. RESULTS: All muscles except the AH could easily be visualized with ultrasound. EI tended to be increased above 60 years and MT was significantly higher in men compared to women, necessitating age- and sex-dependent reference values. CONCLUSIONS: This study shows that muscle ultrasound is capable of visualizing lower leg and foot muscles and reference values for MT and EI can be obtained. Future research will focus on the use of these reference values to evaluate muscle abnormalities caused by neuromuscular disorders like hereditary motor and sensory neuropathy.

Flexible cavovarus feet in Charcot-Marie-Tooth disease treated with first ray proximal dorsiflexion osteotomy combined with soft tissue surgery: a short-term to mid-term outcome study.

OBJECTIVES: The purpose of this paper was to retrospectively evaluate the short-term to mid-term results of combined first ray proximal dorsiflexion osteotomy and soft tissue surgery in treatment of pes cavovarus with a fixed plantar flexed first ray and a passively correctable tarsus due to Charcot-Marie-Tooth disease. PATIENTS AND METHODS: Between January 1995 and July 2005, thirty-three patients with pes cavovarus deformity due to Charcot-Marie-Tooth disease were included. All patients had in common that prior to surgery the hindfoot was passively still adequate correctable at the talonavicular joint. The Coleman block test was performed to establish with certainty that hindfoot varus was a secondary deformity. Fourteen patients were male (21 feet) and nineteen were female (31 feet). Mean age at surgery was 28.1 years (range 13-59 years). Mean follow-up time was 56.9 months (range 13-153 months). Evaluation consisted of physical examination of all patients with assessment of early and late complications. The validated Foot Function Index (FFI) was used to measure pain and impairment. Patients' satisfaction was assessed by a Quality of Care Through the Patients' Eyes (QUOTE) questionnaire. INTERVENTION: Surgical correction of cavovarus foot deformity consisted of dorsiflexion osteotomy at the base of the first metatarsal combined with tendon transfers. Secondary calcaneal osteotomy was performed in case of persistent varus of the calcaneus. RESULTS: No major complications were seen. Recurrence of cavovarus deformity in two feet resulted in triple arthrodesis 37 and 64 months postoperatively. The FFI 5-point score for pain improved from a mean 29.3% to a mean 14.8% (p=0.005). The score for disability improved from a mean 37.8% to a mean 23.5% (p<0.001). Patients' satisfaction was assessed by the QUOTE questionnaire. Seventy percent of the patients could walk barefoot after the operation and 77% of the patients had less pain after surgery. Pressure callosities diminished in 81%. Foot function was considered better after surgery by 84%. Ninety percent was satisfied with the correction of the deformity. CONCLUSIONS: First ray dorsiflexion osteotomy combined with tendon transfers is a good and consistent solution to realign the foot and provides short-term to mid-term satisfactory results in 90% of patients with a rigid forefoot cavus deformity due to plantar flexion of the first ray and with a still passively reducible tarsus.

Foot Build Registration System (FBRS) to evaluate foot posture: a reliability study with healthy subjects and patients with Charcot-Marie-Tooth disease.

BACKGROUND: To follow the weight bearing foot posture in subjects, a measurement tool using digital photography was developed, Foot Build Registration System (FBRS) (Fig. 1) [M. Van der Cruijsen, Voetvorm registratie systeem, Boxmeer (1999).]. This study's objective was to investigate the reproducibility of FBRS measurements in healthy feet and feet of patients with Charcot-Marie-Tooth disease (CMT). METHODS: Reproducibility and reliability studies were performed in several foot views in healthy and CMT patients. RESULTS: These studies showed that the variability of the 95% prediction limit depended upon the foot view being studied and whether markers had been drawn. Some individuals had a higher intra-individual variability than others. Limiting data collection to those individuals with a SD<3.5 degrees for a series of five or more photographs per view improved the 95% prediction limits. These varied between 2.8 degrees and 7.7 degrees. CONCLUSIONS: If the differences found between registration are greater than the abovementioned, values can be attributed to time or operative management for healthy and CMT patients and not to measurement error.

Short-term results of our first 49 Scandanavian total ankle replacements (STAR).

BACKGROUND: Forty-seven consecutive patients treated for ankle arthritis with a Scandinavian total ankle replacement (STAR) by one surgeon were investigated retrospectively. MATERIALS AND METHODS: A modification of the Foot Function Index (FFI), which scores pain and task difficulties, was followed prospectively. Patients were assessed clinically and radiologically. Failure was defined as revision of the prosthesis or arthrodesis for any reason. RESULTS: In 47 patients (16 male, 31 female) 49 total ankle replacements were carried out between May 1999 and June 2004. Indication for surgery was end stage arthritis for rheumatoid arthritis in 29 cases, post-traumatic arthritis in 12, osteoarthritis in five and arthritis secondary to degenerative flatfoot in three. Mean followup time was 28 (12 to 67) months. The modified FFI (range, 0 to 100, a high score meaning more pain and disability) improved significantly from 59 before to 35 after surgery. The mean postoperative Kofoed ankle score was 68. Sixteen procedures were complicated by fractures or temporary neurological damage. At the time of followup, 45 prostheses survived, while four replacements had failed. Radiological examination at followup showed radiolucent lines, osteolysis, and malposition of the components in 31 cases. CONCLUSION: Our results are comparable with those reported in the literature. The clinical outcome improved significantly. Due to aseptic and septic loosening, 8.2% of the prosthesis failed.