A characterization of the geometric architecture of the peritalar joint complex via MRI: an aid to the classification of foot type

The purpose of this work is to study the architecture of the rearfoot using in vivo MR image data. Each data set used in this study is made of sixty sagittal slices of the foot acquired in a 1.5-T commercial GE MR system. We use the live-wire method to delineate boundaries and form the surfaces of the bones. In the first part of this work, we describe a new method to characterize the three-dimensional (3-D) relationships of four bones of the peritalar complex and apply this description technique to data sets from ten normal subjects and from seven pathological cases. In the second part, we propose a procedure to classify feet, based on the values of these new architectural parameters. We conclude that this noninvasive method offers a unique tool to characterize the 3-D architecture of the feet in live patients, based on a set of new architectural parameters. This can be integrated into a set of tools to improve diagnosis and treatment of foot malformations.

Lateromedial and dorsoplantar borders among supplying areas of the nerves innervating the intrinsic muscles of the foot

The branching patterns of nerves supplying the intrinsic muscles of the foot were analyzed as a basis to confirm the muscle layer structure. Thirty-eight feet of 20 Japanese cadavers were examined in detail in this study. The first dorsal interosseus was innervated by a branch from the deep peroneal nerve as well as a branch of the lateral plantar nerve in 92.1%, the second dorsal interosseus in 10. 5% and the third dorsal interosseus in 2.6%. In three specimens, branches from the deep peroneal nerve innervated the oblique head of the adductor hallucis or the lateral head the flexor hallucis brevis. In addition, branches from the medial and lateral plantar nerves and the deep peroneal nerve formed communication loops in three specimens. The first dorsal interosseus, the oblique head of the adductor hallucis and the lateral head of the flexor hallucis and their innervating nerve branches are closely related within the first intermetatarsal space. Since the tibial part of the first interosseus muscle primordium is occupied in the space during development, the variations of innervation patterns and formation of the communicating nerve loops may be explained by various combinations of the part and the other muscle primordia.

A rare anomaly of the abductor digiti minimi muscle of the foot

One case with anomalous fascicles in the abductor digiti minimi muscle (ADM), noted in the course of dissecting the left lower extremity of a 62-year-old male cadaver, is described. The ADM had proximally three bellies and distally one. One of the proximal bellies presented the normal belly and others were the supernumerary fascicles. Both fascicles arose from the calcaneus, one was inserted into the base of the fifth metatarsal (FMB) and the other into the tuberosity of the fifth metatarsal (FMT). One belly coursing distally arose from the FMB and was inserted into the proximal phalanx of the fifth digit. The normal belly ended in the FMB and also both in the distal belly and in the flexor digiti minimi muscle. One of the supernumerary fascicles (medial fascicle) crossed the lateral plantar artery. To our knowledge, this is an anatomic variation which has never been described before. The morphology of this anomaly is discussed in relation to previously described anomalies of the plantar muscles.

Relationship between static and dynamic foot postures in professional baseball players

STUDY DESIGN

Observational study of static and dynamic foot postures in professional baseball players.

BACKGROUND

Throughout the course of a professional baseball season, running, cutting, and sprinting activities can produce a breakdown in players' foot function, causing overuse injuries.

OBJECTIVES

To investigate the relationship between static and dynamic foot postures; to determine the occurrence of abnormal foot postures in professional baseball players and the incidence of overuse injuries in the lower extremity; and to compare the foot postures of pitchers to those of positional players.

METHODS AND MEASURES

The foot postures of 74 professional baseball players were evaluated at rest and during gait. Measures of static foot posture were obtained with a goniometer and included the subtalar neutral position, forefoot/rearfoot position, ankle joint dorsiflexion, tibial angle in standing, and calcaneal angle in standing. The FootTrak motion analysis system provided measures of dynamic foot posture (rearfoot supination and pronation) during the stance phase of gait. A questionnaire was completed by players who reported previous lower extremity injuries. The chi-square statistic was used to determine the associations between forefoot position (varus or valgus) and the amount of foot pronation during gait.

RESULTS

The forefoot varus and calcaneal valgus in standing was significantly associated with the maximum pronation during the stance phase of gait. Of the 65 players who demonstrated excessive pronation (> 8 degrees), 28 (43%) also reported a previous lower extremity injury. No statistically significant difference occurred, however, between injured and uninjured players with respect to the mean values of static or dynamic foot posture. In addition, foot postures were not associated with a player's position.

CONCLUSIONS

Selected measures of static rearfoot and forefoot postures may have value in predicting dynamic rearfoot movement during the stance phase of gait. Excessive pronation in the baseball players we studied was not found to be a significant contributing factor in the development of overuse injuries.

Heterogeneous signal in bone marrow on MRI of children's feet: a normal finding?

OBJECTIVE

To describe the magnetic resonance (MR) appearances of the bone marrow of children's feet and to determine their frequency and significance.

DESIGN AND PATIENTS

A review of MR studies obtained in a retrospective series of 35 children with foot pain and in a prospective series of 19 asymptomatic children was performed. The MR appearances on T1-weighted, T2-weighted and STIR sequences were assessed and the frequency of patchy areas of low signal intensity on T1-weighted and high signal intensity on T2-weighted or STIR sequences was determined and correlated with clinical features.

RESULTS AND CONCLUSIONS

Low signal intensity on T1-weighted and high signal intensity on T2-weighted and STIR sequences were seen in 63% of symptomatic and 57% of asymptomatic children. In all cases where both feet were imaged, the changes were seen bilaterally. The marrow pattern varied from multiple discrete foci to more extensive confluent areas of high signal on the STIR sequence. These appearances are frequent and represent normal variation in the growing skeleton, and should not necessarily be interpreted as a sign of pathology.

Volume of ankle dorsiflexors and plantar flexors determined with stereological techniques

The validity of the methods used for determination of muscle mass has not been evaluated previously. We determined muscle mass by estimating muscle volume with assumption-free stereological techniques applied to magnetic resonance imaging (MRI) in 18 healthy untrained subjects (6 women, 12 men) aged 41 yr (29-64 yr; median, range). Muscle mass was also estimated by measuring leg circumference and cross-sectional muscle areas (CSA) from MRIs at three predetermined levels. Power [peak torque (PT)] of the ankle dorsiflexors and plantar flexors was estimated by using isokinetic dynamometry. Dorsiflexor volume (r2 = 0.76, P < 5 x 10(-6)) and CSA (r2 = 0.73, P < 5 x 10(-5)) were related to PT, whereas circumference was not (r2 = 0.17, not significant). Correspondingly, a relationship to plantar PT was established for plantar flexor volume (r2 = 0.69, P < 5 x 10(-5)) and CSA (r2 = 0.46, P < 5 x 10(-3)) but not leg circumference (r2 = 0.15, not significant). SDs of the residuals were smaller for the relationship between dorsiflexor PT and volume than between PT and CSA (0.42 vs. 0.45) for plantar flexors (1.5 vs. 2.0). By using the Cavalieri method, six MRI sections and 15 min of point counting are sufficient to obtain a valid estimate of the volume of the muscles of the lower leg.

From heel to toe

Modern treatment of foot and ankle disorders must be based around the restoration of normal function and only if the biomechanics of the foot and ankle are properly understood can appropriate treatment programmes be planned. In the past such programmes have been arbitrary, often based on fusion which could not ever restore normal foot function. However, when one combines the experience of historical treatment techniques with modern biomechanical principles, a new and modern approach can be adopted so that new treatment protocols can be developed.

Does arch height affect impact loading at the lower back level in running?

The purpose of this study was to evaluate the influence of the medial longitudinal arch height on the shock wave that repetitively reaches the lower back in running. Impact forces were measured simultaneously at the ground by a force plate and at the level of the low back, by means of an accelerometer, skin-mounted at the L3 spinal process. The medial longitudinal arch height was calculated as navicular height divided by foot length. Twelve healthy subjects ran barefoot and with an identical sport shoe at a constant speed. The sample size was divided equally into a low-arch and a high-arch group. Statistical analysis was performed by multivariate analysis of variance and Pearson's correlation. At low back level, there was a significantly lower acceleration amplitude and rate in the high-arch group (amplitude = mean, 1.74 g and SD, 0.94 g; rate = mean, 71.2 g/sec and SD, 58.0 g/sec) compared with the low-arch group (amplitude = mean 2.25 g and SD, 1.11 g; rate = mean, 111.5 g/sec and SD, 68.6 g/sec) (P < 0.001, each). At the ground, there was a slight negative correlation between arch height and initial loading rate in AP (-0.19; P < 0.01) and vertical (-0.22; P < 0.001) directions and a positive correlation between arch height and initial loading rate in the medial direction (0.22, P < 0.05). The results indicate that the high-arch foot is a better shock absorber with regard to the low back level than the low-arch foot.

Structural and functional predictors of regional peak pressures under the foot during walking

The objective of this study was to identify structural and functional factors which are predictors of peak pressure underneath the human foot during walking. Peak plantar pressure during walking and eight data sets of structural and functional measures were collected on 55 asymptomatic subjects between 20 and 70 yr. A best subset regression approach was used to establish models which predicted peak regional pressure under the foot. Potential predictor variables were chosen from physical characteristics, anthropometric data, passive range of motion (PROM), measurements from standardized weight bearing foot radiographs, mechanical properties of the plantar soft tissue, stride parameters, foot motion in 3D, and EMG during walking. Peak pressure values under the rearfoot, midfoot, MTH1, and hallux were measured. Heel pressure was a function of linear kinematics, longitudinal arch structure, thickness of plantar soft tissue, and age. Midfoot pressure prediction was dominated by arch structure, while MTH1 pressure was a function of radiographic measurements, talo-crural joint motion, and gastrocnemius activity. Hallux pressure was a function of structural measures and MTP1 joint motion. Foot structure and function predicted only approximately 50% of the variance in peak pressure, although the relative contributions in different anatomical regions varied dramatically. Structure was dominant in predicting peak pressure under the midfoot and MTH1, while both structure and function were important at the heel and hallux. The predictive models developed in this study give insight into potential etiological factors associated with elevated plantar pressure. They also provide direction for future studies designed to reduce elevated pressure in "at-risk" patients.

Insertion of the abductor hallucis muscle in feet with and without hallux valgus

Textbooks of human anatomy present different opinions on the insertion of the abductor hallucis muscle which is concerned in etiology as well as in therapy of hallux valgus. In plastic and reconstructive surgery the muscle is taken as a graft for flap-surgery. In this study 109 feet (58 right, 51 left) were examined, 18 of these with clinical hallux valgus. The tendon of the muscle may attach to the tendon of the medial head of the short flexor hallucis muscle where a subtendineous bursa can be found. At the head of the first metatarsal bone the joint capsule is reinforced by fibres arising from the medial sesamoid bone which may be called "medial sesamoidal ligament." The tendon passes the first metatarsophalangeal joint plantarily to its transverse axis. Three types of insertion could be distinguished: type A, insertion at the proximal phalanx (N = 42); type B, insertion at the medial sesamoid ligament and at the medial sesamoid bone (N = 65); type C, insertion at the medial sesamoid bone (N = 2). In all types superficial fibres of the tendon extended to the medial and plantar sides of the base of the proximal phalanx, running in a plantar to dorsal direction. Statistical analysis exposed neither significant differences between both sides nor significant difference between normal feet and feet with hallux valgus. Therefore, a specific pattern of insertion of the abductor hallucis muscle in hallux valgus cannot be stated.

Tarsal tunnel syndrome: a review of the literature

Tarsal tunnel syndrome is an uncommon clinical entity. This article will review the published reports on tarsal tunnel syndrome with respect to its anatomy, cause, pathophysiology, clinical presentation, diagnosis, treatment, and results of treatment in an attempt to improve understanding of this problem.

Relative forefoot abduction and its relationship to foot length in vitro

BACKGROUND

The human foot is often modelled as a rigid body in gait analysis. A more realistic model separates this segment into a forefoot and rearfoot. However, no three-dimensional data has been published on dynamic relative ab-adduction between these segments, and how this impacts changes in foot shape.

OBJECTIVE

The purpose was to quantify three-dimensionally forefoot ab-adduction relative to the rearfoot in vitro, and to determine how forefoot ab-adduction affects foot length.

METHODS

Video data were collected from reflective marker triads affixed to the ends of Steinmann pins drilled into the tibia, calcaneus, cuboid, and the first and fifth metatarsal bones. Medial and lateral foot length and forefoot ab-adduction relative to the rearfoot were calculated under two axial tibial loads (200 N, 600 N) and two input motions (dorsi-plantarflexion, internal-external tibial rotation).

RESULTS

It was found that patterns of change for each variable were dependent on the degree of rigidity of the foot. Relative forefoot ab-adduction values ranged from 4.4 degrees of adduction to 1.7 degrees of abduction. Medial foot length values changed +/- 0.8 mm (+/- 0.5%) and lateral foot length values changed +/- 0.5 mm (+/- 0.3%). Medial foot length was correlated positively with relative forefoot abduction, and external tibial rotation was correlated positively with relative forefoot adduction.

Medial longitudinal arch of the foot: stationary versus walking measures

We describe the characteristics of the medial longitudinal arch (MLA) of the right foot in 19 healthy men while sitting/partial bodyweight, standing/full bodyweight, and during the stance phase of walking. Three measurements were selected as representative of the MLA, including: height of the arch, length of the arch, and supranavicular angle. Mean values were calculated in three dimensions for each measure in the sitting and standing conditions and for the minimum value of each measure in the walking condition. Patterns measured during walking had high association (r = 0.999) and could be related to phases of stance. In the stationary conditions, the MLA varied significantly (P<0.001). No significant relationship of arch height, arch length, or supranavicular angle was found between sitting and standing or between stationary and walking conditions. It was concluded that none of the static variables could be used to predict others and that static measures of the MLA do not predict the dynamic motion of the MLA. The MLA may not be a reasonable indicator of behavior or motion of the foot.

The relation between height, foot length, pelvic adequacy and mode of delivery

OBJECTIVE

To investigate the value of maternal height and foot length as predictors of pelvic adequacy and to evaluate the influence of body components' proportions on the mode of delivery.

METHODS

Retrospective study of the anthropometry of women having normal vertex deliveries (NVD), caesarean sections (CS) and vaginal birth after caesarean (VBAC).

RESULTS

NVD patients were taller, had a longer vertebral column, longer lower limbs and longer feet than CS and than VBAC patients. The anthropometric measurements of VBAC patients yielded values intermediate between CS and NVD patients. The ratios of height to any of the other measured variables (vertebral column, lower limb and foot length) were similar in the three groups indicating that the body proportions were the same.

CONCLUSION

Maternal height and foot length are of limited value as predictors of pelvic (in-)adequacy. The anthropometric features of women delivered by CS only are similar to those of women having a vaginal birth after Caesarean.

Limb salvage with Chopart's amputation and tendon balancing

For several decades, Chopart's amputation has met with some skepticism owing to reports of significant equinus deformity developing soon after the procedure is performed. However, with appropriate tendon balancing, which generally includes anterior tibial tendon transfer and tendo Achillis lengthening, this level of amputation is often more functional than slightly more distal amputations, such as Lisfranc or short transmetatarsal amputations. The authors offer a rationale for this observation, which includes a discussion of the longitudinal and transverse arch concept of the foot. This concept dictates that the shorter the midfoot-level amputation, the more likely the patient is to develop an equinovarus deformity, thus exposing the fifth metatarsal base and cuboid to weightbearing stress and a high risk of ulceration. Chopart's amputation, in eliminating the cuboid, often obviates the potential varus deformity and thus can have a more acceptable long-term result.

Evolution of the rearfoot. A model of adaptation with evidence from the fossil record

The evolution of the human foot presents an obfuscation: explanations for its occurrence and the exact nature of mechanisms of change are still not fully understood. This article outlines a model of adaptation from a primitive ape foot and presents this as a hypothesis. Evidence substantiating the hypothesis is then presented, which explains many of the large-scale features distinctive to the human foot. Further evidence is then presented that goes some way toward explaining the sequence of modification with first the lateral side becoming adapted for terrestrial function followed by the medial side. Paradoxically, this was hypothesized by Morton more than half a century ago in his "hypothetical prehuman foot," though it was not accepted favorably at the time.

Relationship between foot length and the inter anterior superior iliac distance

Reduction of unstable pelvic fracture by external fixator might be over or under corrected as there is no proper estimation from the surgical landmark. Radiographic evaluation after reduction must be carried out and improper reduction is found in a certain number. To find a better guide by normal surgical landmark the study was carried out as a survey research in 600 volunteers aged from 10 to 70 years. Simple caliper and tape were used to measure the height, foot length and inter anterior superior iliac spine distance. In 376/420 male volunteers (89%), the length between right heel and tip of the fourth toe was equal to the inter anterior superior iliac spine distance. In 173/180 female volunteers (96%), the length between right heel and tip of big toe was equal to the inter anterior superior iliac spine distance. The length of the right foot can be used as a reference in reducing unstable fractured pelvis by external fixation. These data were used in the management of 36 patients with unstable fractured pelvis with external fixation for reduction and stabilization. All had good results.

The effects of unilateral pyramidal tract section on hindlimb motor performance in the rat

Most investigations on selective lesions of the pyramidal tract in rodents have focused on the functional impairment of the forelimbs. This study describes the effects of a unilateral transection of the pyramidal tract rostral to the decussation on hindlimb function. Using kinematic locomotion analysis, the narrow beam test, open field locomotion ranking, analysis of footprints and air righting, we found severe impairments including hypermetria, trunk instability, lateral shifts in weight support, toe dragging, and hindlimb exo-rotation. Most impairments recovered rapidly within the first week after operation. Slight hypermetria persisted after 4 weeks. The rather mild long term deficits after unilateral pyramidotomy may stress the need for extremely sensitive behavioural tasks to enable the detection. We conclude that the possibility to correlate regenerative changes following selective pyramidal tract lesions with hindlimb function is thus limited.

Regional difference in epidermal thinning after skin denervation

Denervation of skin has a profound influence on epidermis; epidermal thinning was a consistent finding in rats. However, it is not clear whether the degree of epidermal thinning was similar in the region receiving the same innervation. In mice, how early epidermal nerves were degenerated after nerve injury remained unknown. To address these issues, we transected the sciatic nerve in mice and compared the changes of epidermal thickness in different areas of the hind foot skin. Epidermal nerves degenerated within 48 h after nerve transection, similar to what was observed in rats. Seven days after nerve transection, there was differential thinning of epidermis. The interpad area, in the center of the sciatic nerve-innervated region, exhibited the most profound degree of epidermal thinning (34.6 +/- 3.1 vs 47.8 +/- 2.4 microns, P < 0.01). The heel area, in the periphery of the sciatic nerve-innervated zone, did not show significant thinning of epidermis after denervation (37.3 +/- 4.8 vs 41.5 +/- 5.1 microns, P > 0.05). The degree of epidermal thinning after denervation in the pad area was the intermediate one: with 98.8 +/- 4.8 vs 120.1 +/- 7.3 microns, P < 0.02, in the rete pegs, and 51.1 +/- 4.1 vs 62.1 +/- 6.0 microns, P < 0.02, in the dermal papilla. The differential thinning was obvious when the thickness of the denervated epidermis was normalized to that of the control epidermis with the ratios of 0.73 +/- 0.03 in the interpad area, 0.83 +/- 0.04 in the rete peg, 0.85 +/- 0.05 in the dermal papilla, and 0.92 +/- 0.05 in the heel. Epidermal thinning was reversed by reinnervation of the epidermis after sciatic nerve crush (41.5 +/- 1.5 vs 45.0 +/- 2.0 microns in the interpad area, P > 0.05). These findings suggest that sensory nerves exhibit trophic influences on the epidermis presumably through the effects of diffusible factors.

Electrodiagnostic evaluation of the foot

Focal entrapment neuropathies in the foot, as compared to those of the hand, represent a daunting diagnostic challenge to many electromyographers. This article emphasizes an understanding of the anatomy of the foot as a fundamental key to its electrodiagnostic evaluation. The anatomic course of specific nerves will be described in terms of entrapment sites, and the clinical and electrophysiologic manifestations of each nerve entrapment will be discussed.

Leg stiffness and foot orientations during running

This study was done to determine whether leg stiffness (Kleg) during running was related to rearfoot-to-forefoot angle in standing (RFAst) and running (RFArun). Footprints obtained from 32 subjects were used to calculate RFAst and RFArun, defined as positive when forefoot axis was abducted from rearfoot axis. A spring-mass model was used to calculate Kleg in running from ground reaction forces, measured by a force platform. The Kleg of runners (13.0 +/- 2.7 kN x m(-1)) was negatively correlated with RFAst (-8.4 degrees +/- 6.4 degrees) and RFArun (-0.4 degrees +/- 7.2 degrees). When runners were divided into opened foot (RFArun > 0; N = 19) and closed foot (RFArun < 0; N = 12) groups, the Kleg of opened foot runners was less than that of the closed runners. We suggest that foot structure is a factor responsible for the differences in leg stiffness observed in runners.