Forefoot deformation during stance: does the forefoot collapse during loading?

This study presents a specific description of forefoot deformation during the stance phase of normal human walking based on the combined analysis of pressure and three-dimensional optoelectronic measurements. Forefoot deformation is measured in forty healthy subjects using (1) a six-camera motion capture system (sampled at 250 Hz) tracking five reflective skin markers attached to the forefoot, (2) a pressure platform (sampled at 500 Hz) and (3) a forceplate (sampled at 1250 Hz). Forefoot deformation is characterized by the forefoot width, the mediolateral metatarsal arch height and the plantar pressure under the metatarsal heads. Using this setup, a typical pattern of forefoot motion is described during stance phase: From a flexible, compliant configuration at the beginning of stance phase, characterized by a decrease in mediolateral metatarsal arch height and a controlled increase in forefoot width, the forefoot turns into a stable configuration during midstance. Subsequently, the increase in mediolateral arch height and the decrease in forefoot width describe the transformation into a tight configuration during final stance. This transfer from a compliant into a rigid configuration through stance phase rejects the idea of the forefoot as a collapsing structure under increased loading.

Changed cervical kinematics after fusion surgery.

PURPOSE: Analyzing and comparing the range of motion and movement pattern of subjects who underwent an anterior cervical fusion using trabecular metal with control subjects. METHODS: Three-dimensional kinematics of planar active axial rotation and active lateral bending of 50 experimental and 41 control subjects were registered by means of an electromagnetic tracking system. RESULTS: Comparing the experimental group with the control group reveals that the range of the main motion component differs significantly (p < 0.01) during the active axial rotation and lateral bending movement. During active axial rotation, the coupled lateral bending motion component also differs between both groups. The root mean square value of the jerkiness (derivative of the acceleration) and de deviation from the 6-polynomial smoothed function of the main as well as the coupled motion component express the qualitative aspects of kinematics and are significantly different between the experimental and the control group for both movements (p < 0.05). CONCLUSIONS: Subjects who have an anterior cervical fusion with trabecular metal show significant quantitative as well as qualitative differences in cervical kinematics during active axial rotation and lateral bending compared to control subjects.

Direct relationship of body mass index and waist circumference with body tissue distribution in elderly persons.

OBJECTIVES: To explore the relationship of BMI and WC with muscle/adipose tissue mass ratios and with trunk adipose tissue distribution, based on an anatomical 5-compartment model, by dissection of cadavers of elderly persons. DESIGN: Cross-sectional explorative study. SETTING: Brussels Cadaver Analysis Study. PARTICIPANTS: Cadavers of twenty-nine white Caucasian elderly persons (17 females and 12 males, aged 78.1±6.9 years). MEASUREMENTS: Whole body and trunk composition were determined at the anatomical tissue-system level by direct dissection. RESULTS: BMI and WC were significantly and positively related to absolute tissue masses in both sexes. Muscle tissue mass, adipose tissue mass and trunk internal adipose tissue mass correlated better with BMI (r-values between 0.68 and 0.89) than with WC (r-values between 0.49 and 0.71). BMI was significantly and inversely related with various muscle/adipose tissue ratios in both sexes (r-values between -0.54 and -0.68). WC correlated with muscle/adipose tissue ratios in females only (r-values between -0.55 and -0.64). BMI was also significantly related to trunk adipose tissue distribution in elderly females, but not in males. When comparing individual tissue proportions within and between adjacent BMI-classifications or WC categories, body composition varied considerably. CONCLUSION: Our results show that BMI and WC are significantly related with adipose tissue mass and with several ratios of muscle to adipose tissue in elderly subjects. However, cautious clinical interpretation is warranted since important differences in tissue mass proportions were found in subjects with similar BMI and/or WC values.

Morphology and kinematics of the atlanto-axial joints and their interaction during manual cervical rotation mobilization.

BACKGROUND DATA: At present little data are available on the relationship between spinal anatomy and kinematics. No studies have verified the relationship between atlanto-axial kinematics during manual mobilization and the spatial features of the atlanto-axial ligaments and the lateral joints. MATERIALS AND METHODS: Twenty un-embalmed cervical spine specimens (9 male and 11 female; 80 ± 11 years) were studied. Atlanto-axial kinematics were registered during manual axial rotation mobilization using an ultrasound-based motion tracking system. Anatomical landmarks were digitized and spatial features of the lateral atlanto-axial joint surfaces and alar ligaments were extracted. The relationship between the anatomical features and the spinal kinematics was analyzed using statistical regression analysis. RESULTS: Only the range of motion of the coupled flexion-extension motion component, the ratio and the time shift between main axial rotation and coupled lateral bending motion components could be predicted for about 52%, 49% and 73%, respectively, by a selected set of anatomical features. CONCLUSION: Supposed relationships between anatomical features and joint kinematics are only partially confirmed. The results indicate that the kinematics of the atlanto-axial joint during manual regional axial mobilization are not completely predetermined by the specimens' specific anatomy.

Magnetic resonance imaging of anatomical variants of the subtalar joint.

OBJECTIVE: To evaluate MRI with thin slices to depict anatomical variations of the subtalar and talocalcaneonavicular joints. METHODS AND MATERIALS: Ankle MRI was performed in 51 patients. The articular configurations were differentiated on sagittal T1-weighted and three-dimensional (3D) DESS images. Multiplanar reconstructions were performed. The variation in curvature of the posterior facet of the calcaneus and talus was analysed. 3D surface-rendered images of the calcaneus were obtained. All images were studied by an experienced physical therapist. RESULTS: Analysis revealed that 18 (36.7%) of the subjects had 3 distinct facets on the calcaneus. A missing anterior facet was revealed in five (10.2%) of subjects. Twenty-six (53.1%) subjects showed a fusion of the anterior and middle facets. In four cases, an articulation was found between the talus and the cuboid bone. At the posterior talocalcaneal articulation, variations were observed of the curvature of the medial side of the joint. CONCLUSIONS: The configuration of the facets of the talocalcaneal joints can be analysed on MR images. On 3D images, an articular connection was seen between the talus and the cuboid bone, as well as variations in the curvature of the posterior talocalcaneal joint. These anatomical variations may have implications for mobility and stability of the ankle.

Hazards of hydrodensitometry.

The limitations of the two-component model of body composition have been investigated extensively in the past resulting in a clear message of violation of basic assumptions underlying its use. This strong message may or may not be appropriate, since hydrodensitometry is still used, in particular in sports sciences. The combination of novel information with previously described indicators should allow to confirm or reject the pretended violation of basic assumptions underlying the use of hydrodensitometry. Water content of adipose tissue (AT) and of AT free mass as opposed to fat and fat free mass, and bone density of separate bones was obtained from the Brussels Cadaver Analysis Study collection. Analysis of different studies indicated anomalies up to -12% fat but also suggests that the borderline between chemical and morphological interpretations becomes vague and the ad hoc terminology does not reflect reality. Predicted % body fat using different methods on the same individual ranges between 9.6% up to 21% of AT. Total body water of separate tissues suggests intra-and intervariability within tissues. Whole skeleton density and the separate bone density cannot support the two-component constancy (1.164 g/mL to 1.570 g/mL).

The talocalcaneal unit: pictorial review of anatomy and pathologic conditions on multi detector CT.

Normal anatomy of the subtalar joints is illustrated in cadaveric specimens. Variations of the subtalar joints include three facets, fused middle and anterior facet, and missing anterior facet. Patients were studied by means of Multi Detector Computed Tomography (MDCT) to provide clinical examples of subtalar pathology including traumatic and non traumatic disorders.

A pictorial overview of ultrasound of tendon disorders.

A variety of terms that is often confusing is used to describe tendon changes at ultrasound.The classification of tendon disorders is often based on a combination of clinical and imaging findings. We present an overview of different categories of tendon disorders where ultrasound may contribute to the diagnosis and classification. We suggest the following categories: overuse, traumatic, inflammatory, and metabolic.The differentiation is not always possible and the importance of clinical data must be taken into account.The spectrum of tendon abnormalities is illustrated with clinical examples.

Reproducibility of kinematic motion coupling parameters during manual upper cervical axial rotation mobilization: a 3-dimensional in vitro study of the atlanto-axial joint.

INTRODUCTION: The reproducibility of the 3-dimensional (3D) kinematic aspects of motion coupling patterns of segmental manual mobilizing techniques is not yet known. This study analyzes the segmental 3D aspects of manual mobilization of the atlanto-axial joint in vitro. METHODS AND MATERIALS: Twenty fresh human cervical specimens were studied in a test-retest situation with two examiners. The specimens were manually mobilized using three different techniques: a regional mobilization technique, a segmental mobilization technique on the atlas with manual fixation of the axis and a segmental mobilization applying a locking technique. Segmental kinematics were registered with a Zebris CMS20 ultrasound-based tracking system. The 3D aspects of motion coupling between main axial rotation and coupled lateral bending were analyzed by six parameters: the range of motion the three motion components, the cross-correlation, the ratio and the shift. RESULTS: The results indicate stronger intra- than inter-examiner reproducibility. The range of motion of the axial rotation component shows a substantial level of intra- and inter-examiner reproducibility (ICC's 0.67-0.76). The parameters describing the coupling patterns show only moderate to substantial intra-examiner reproducibility for the more experienced of the two examiners (ICC's 0.55-0.68). All other correlations were not significant and no differences could be observed between regional versus segmental techniques. CONCLUSION: Reproducibility of segmental 3D-aspects of manual mobilization of the atlanto-axial joint in an in vitro situation can differ between examiners. The results of the present study may indicate a possible tendency to higher reproducibility if mobilizations are performed by an examiner with high expertise and experience in applying the specific techniques. Continued investigation including more examiners with different levels of experience and different techniques is necessary to confirm these observations.

The role of the axillary arch (of Langer) in the management and the kinesiology of the overhead shoulder mobility.

AIM: Based on cadaveric, neurosurgical and medico-diagnostic evidence the axillary arch of Langer (AA) is assumed to create symptoms similar to those of entrapment or obstruction type syndromes, e.g. Thoracic Outlet Syndrome. Although the incidence of a AA varies between studies and races, there are many assumptions that its frequency and its axillary location influences the motor control of the shoulder girdle. In addition to the existing anatomical evidence and based on functional reasoning it can be predicted that the AA influences the shoulder girdle kinesiology in vivo also. However no study is known that verifies these functional assumptions in vivo. METHODS: In order to complete our knowledge of the AA we evaluated strength, endurance, motor control, precision and proprioception in vivo, e.g. hand held dynamometry, abduction and adduction shoulder strength and endurance, functional exercise assessment, throwing impact force on a (precision) target and shoulder joint position sense were measured in two groups of athletes and physical education students, one with an AA (N.=22) and a control group without AA (N.=22). RESULTS: The results indicate a significant (p<0.05) influence of the presence of an AA on strength, endurance and motor control increase in women associated with an increase of paraesthetics. For all these parameters no significant difference occurred in men. The throwing and proprioceptive joint position sense data however indicate a clear (P<0.05) increase of impact forces suggesting a possible shoulder stabilisation and an improvement of proprioception both in men and most in women. CONCLUSION: These finding have both a functional and clinical relevance and do not fully confirm the anatomical predictions from the cadaveric evidence nor support the (surgical) diagnoses of excision of the AA of Langer in throwing in athletes.

MRI of cartilage and subchondral bone injury. A pictorial review.

In this article, we present an overview of various cartilage and subchondral bone abnormalities seen on MRI. Injury of bone is often associated with cartilage damage and vice versa. A number of common conditions affecting joints typically show certain combinations of chondral and subchondral changes.

Lack of impairment of kinaesthetic sensibility in cervicogenic headache patients.

To compare the cervical kinaesthetic sensibility of cervicogenic headache (CEH) patients and asymptomatic controls, the head repositioning accuracy of 10 CEH patients and 23 asymptomatic controls was measured. Should an impaired kinaesthetic sensibility be demonstrated, its assessment could be of diagnostic value in the evaluation of patients with suspected CEH. Additionally, specific exercises to improve cervical kinaesthesia could be prescribed. Kinaesthetic sensibility was assessed using a head repositioning task: subjects were asked to relocate their heads as accurately as possible to a previously memorized head position following an active movement (flexion, extension and left and right rotations). The repositioning error was registered using a validated magnetic tracking device (Flock of Birds). No significant differences were found between the asymptomatic controls and the CEH patients (independent-samples T-test, P < 0.05). We conclude that cervical kinaesthetic sensibility is not impaired in non-traumatic CEH. The use of kinaesthetic assessment and treatment in this patient group seems to be limited.

[Left-right asymmetries and other common anatomical variants of temporomandibular articular surfaces]. / Links-rechts asymmetriën en andere anatomische varianten van de temporomandibulaire gewrichtsvlakken.

The purpose of the study was to investigate left-right asymmetries and other anatomical variants of temporomandibular articular surfaces. Digital photography and macroscopic observation were used to gather information about the shape, size, orientation and degeneration of temporomandibular articular surfaces of 100 skull bases and 100 mandibles. Left-right asymmetries in shape, size, orientation and degeneration were found in 39.5, 26, 16 and 31.5% of the mandibular surfaces respectively. The glenoid fossae showed left-right asymmetries in size, orientation and degeneration in 4.1 and 22.5% of cases respectively. Left-right asymmetries in orientation were found in 24% of the articular eminences. Anatomical variants of the mandibular articular surfaces were found as differences in shape: the majority had horizontal oblong outlines and rounded frontal outlines; one fifth showed pear-shaped horizontal outlines and flat or ridge-shaped frontal outlines. The important incidence of left-right asymmetries and anatomical variants of temporomandibular articular surfaces must be considered when observing and treating temporomandibular dysfunction. It can be expected that these asymmetries and anatomical variants may have arthrokinematic consequences for treatment of temporomandibular dysfunction.

Does manual mobilization influence motion coupling patterns in the atlanto-axial joint?

BACKGROUND: A restricted number of publications have reported on the analysis of coupling patterns in the atlanto-axial joint using an in vitro set-up applying pure moments of forces. The aim of this study is to analyze segmental motion coupling patterns during cervical manual mobilization. METHODS: The position and attitudes of sensors mounted on the atlas and axis were traced in nine embalmed and one fresh human spinal specimen using an electromagnetic tracking system. Segmental bony reference points were registered using a 3D-digitizing stylus for the definition of bone embedded coordinate systems. Segmental motion coupling was recorded for the atlanto-axial joints during manual mobilization through the full range of axial rotation and lateral bending. RESULTS: Coupled motions were described by the direction of the associated motion and by cross-correlation analysis. The results confirm the contra-lateral coupling pattern of axial rotation with lateral bending at C1-C2 observed in previous studies. The cross-correlation analysis offered a more objective interpretation of the coupling pattern for the analysis of the more irregular coupling patterns during lateral bending. Inter-individual differences in coupling patterns were observed. INTERPRETATIONS: The presented method provides possibilities for the study of coupled motion during manual diagnostic and therapeutic practice. Practitioners should be aware of the segmental 3D-aspects of manually induced so called planar mobilizations and their possible influence on motion coupling. Motion coupling patterns may be related to specimen specific anatomy.

3D morphometry of the transverse and alar ligaments in the occipito-atlanto-axial complex: an in vitro analysis.

This study verifies the three-dimensional anatomical features of the transverse and alar ligaments with reference to the axis using a direct in vitro approach. In 20 fresh spine specimens, metal markers were inserted on the cranium, atlas, and axis. After registration of the intact specimen, the bony segments were separated, and markers and anatomical landmarks were digitized. The length and the orientation of the ligaments with reference to the axis were derived from the relative position data. The transverse ligaments of the atlas have a mean estimated length of 21 mm and an absolute angle (i.e., independent of any reference frame) of 119 degrees +/- 17 degrees . The alar ligaments have a mean length of 9 +/- 2.5 mm, and the mean absolute angle between the ligaments is 117 degrees +/- 31 degrees . The plane of the alar ligaments shows a mean backward inclination of -10 degrees +/- 52 degrees . This plane has a mean inclination of 6 degrees +/- 4 degrees with reference to the sagittal plane indicating left-right symmetries. The transverse ligament arches around the dens and demonstrating its function as a stabilizer for the dens as well as guidance for axial rotation movements. A posterior inclination of the alar ligaments may induce a coupled extension in combination with a lateral bending during axial rotation. These detailed aspects of motion steering may be important to consider when attempting to reduce or restore movement.

Manual fixation versus locking during upper cervical segmental mobilization. Part 1: an in vitro three-dimensional arthrokinematic analysis of manual flexion-extension mobilization of the atlanto-occipital joint.

BACKGROUND: Segmental manual spinal mobilization techniques are used to restrict the effects of interventions to one spinal segment. It is, however, not known whether it is possible to generate such a localization of effects. Segmental motion in the cervical spine was previously studied by applying pure moments of force on cadaver specimens. So far, no studies have been performed on the segmental three-dimensional (3D)-kinematic aspects of cervical manual flexion-extension mobilization. METHODS: 3D-aspects of manual flexion-extension motion in the atlanto-occipital and atlanto-axial segments were analysed in vitro using an electromagnetic tracking device. Segmental bony reference points were registered using a 3D-digitizing stylus to define bone-embedded coordinate frames. Six spinal specimens--five embalmed and one fresh--were analysed in this study. Segmental motions were analysed in the atlanto-occipital and the atlanto-axial joints during manual mobilization through the full range of flexion-extension mobility. The 3D-kinematic analysis of two different segmental mobilization techniques--manual fixation of C1 versus locking of the inferior cervical spine--is presented. RESULTS: A significant reduction (P<0.05) of the associated axial rotation and lateral bending motions was observed during the manual fixation technique without influencing the main motion component of flexion-extension. The locking technique did not significantly influence the movements on the mobilized atlanto-occipital segment, but reduced all movement components in the atlanto-axial joint. INTERPRETATIONS: The results suggest that, for manual segmental flexion-extension mobilization of the upper cervical spine, manual fixation or locking might be chosen in different situations according to the desired effects.

Manual fixation versus locking during upper cervical segmental mobilization. Part 2: an in vitro three-dimensional arthrokinematic analysis of manual axial rotation and lateral bending mobilization of the atlanto-axial joint.

BACKGROUND: Three-dimensional kinematic aspects of coupled motion during manual cervical mobilization have not previously been studied. Using an in vitro 3D-motion analysis method, the kinematic effects of two different segmental techniques for axial rotation and lateral bending mobilization of the upper cervical spine were investigated as a second part of the study (in part one, kinematic effects of flexion-extension mobilization have been investigated). METHODS: Axial rotation and lateral bending mobilization of the atlanto-occipital and atlanto-axial segments were analysed in vitro using an electromagnetic tracking device. Local reference frames were defined based on bony reference points that were registered using a 3D-digitizing stylus. Five embalmed and one fresh specimen were analysed. Segmental motion was registered simultaneously in the atlanto-occipital and the atlanto-axial joints during manual mobilization through the full range of axial rotation and lateral bending mobility. The 3D-kinematic aspects during regional mobilization were compared with those during segmental mobilization with manual fixation and during segmental mobilization using a locking technique. RESULTS: During both segmental axial rotation techniques of the atlanto-axial joint, a significant reduction of the coupled lateral bending and flexion-extension motion was observed. The locking technique also induced an increase in the main axial rotation component. During lateral bending mobilization of the atlanto-axial joint, the manual fixation technique reduced the effect on the coupled flexion-extension component significantly. INTERPRETATIONS: These results suggest that for manual segmental axial rotation and lateral bending mobilization of the upper cervical spine segmental manual fixation or locking may be preferred in different situations depending on the desired effects. This study brings additional information to the data provided by part 1 of this study on the 3D-arthrokinematic effects of flexion-extension mobilization.

Morphological and constitutional comparison of age-matched in-vivo and post-mortem populations.

Cadaver studies are often used as a reference in clinical studies and in-vivo Body Composition (BC). However, there is a paucity of comparative information between in-vivo and post-mortem populations. Forty living volunteers for the study (18 males and 22 females, age range 55-92 years) were age-matched with a sample of 26 well-preserved cadavers (13 males and 13 females). Twenty eight anthropometric variables were chosen, i.e. nine circumferences, eight breadths, four lengths, five skinfolds, weight and height. These were measured both in vivo and post-mortem. All measures were taken according to Martin and Saller (1957), Clauser et al. (1969) and Clarys et al. (1984). Normality verification, Variant Analysis (one way Anova) and Mollison transformations were used for the comparative treatment. Data from this study confirm that the in-vivo and post mortem macro morphology are in agreement. The best similarities were found between the female groups. This study confirms that cadaver research is reliable for the validation of in-vivo techniques and as a reference standard in the absence of other direct validation measures.

Measurement of three-dimensional intra-articular kinematics: methodological and interpretation problems.

Intra-articular kinematics evaluates joint motion in terms of the configuration of the joint. Therefore data are needed concerning joint kinematics as well as joint configuration. We have developed accurate measurement methods for both in vivo and in vitro evaluation. Interpretation of the processed data is more complex than simply setting up a coordinate system based on the joint configuration. Although the description of intra-articular motion in terms of Euler-Cardan or helical angles may be complete, the therapeutic interpretation may be doubtful. Using the the ulno-humeral joint during flexion-extension as an example, we found the combination of helical angles in the directions of extension/external rotation/varus. In the case of the Cardan angles, inconsistent patterns of rotation resulted from a different choice of sequence order and were different from the helical angles. The finite helical axis (FHA) provides a functional representation of the joint movement, i.e. pathways of motion, whereas the sequence dependency of Euler-Cardan angles produces problems in the therapeutic interpretation of the movement. Therefore we believe that an FHA approach should be used in intra-articular kinematics research.

Arthro-kinematics of the elbow: study of the carrying angle.

The carrying angle of the elbow is usually assessed in full elbow extension, with a protractor goniometer, or derived from X-ray images. Substantial differences in carrying angle values have been reported, possibly explained by methodological differences. Carrying angles tend to show higher values in women than in men. The aim of this study was to confirm the previously described progressive decrease of the carrying angle as a function of increasing elbow flexion. After assessment of the carrying angle with a protractor goniometer and an electromagnetic tracking system (Flock of Birds) in extension, flexion-extension movements with the forearm held in supination were recorded by means of the latter system. Three recordings were averaged in both the left and the right elbows of 20 volunteers without a history of elbow pathology (10 males and 10 females; mean age 25 years). In extension, a mean (+/- SD) carrying angle of 11.6 +/- 3.2 degrees was found in the male and 16.7 +/- 2.6 degrees in the female subjects. The carrying angles progressively decreased with flexion, at the end changing into a mean (+/- SD) varus angle of 1.8 +/- 2.9 degrees in men and 1.6 +/- 2.3 degrees in women. Significant differences in carrying angles between the sexes were recorded in moving from 0 to 30 degrees of flexion (p < 0.03 for the left and p < 0.01 for the right elbows), but disappeared beyond 30 degrees . No statistically significant differences were found between the results of left and right elbows. Although statistically significant differences (p < 0.05 to p < 0.001) were found along the course of flexion and extension, these differences were small (<0.6 degrees ). The mean carrying angles at 0, 30, 60, 90 and 120 degrees of flexion revealed larger standard deviations in the male group than in the female group.