Three-dimensional kinematics of the cervical spine using an electromagnetic tracking device. Differences between healthy subjects and subjects with non-specific neck pain and the effect of age.

BACKGROUND: A cross-sectional observational study of three-dimensional cervical kinematics in 35 non-specific neck pain patients and 100 asymptomatic controls. To compare qualitative and quantitative aspects of cervical kinematics between healthy subjects and subjects with non-specific neck pain and to determine the effect of age on cervical kinematics in healthy subjects. METHODS: Three-dimensional kinematics of active lateral bending and flexion-extension of 35 patients and 100 controls were registered by means of an electromagnetic tracking system. The means of several kinematic parameters were compared using t-tests. In addition, we assessed the age-dependency of the three-dimensional kinematic parameters by stratifying the 100 control subjects in 6 age categories. FINDINGS: Comparison of the patient group with the control group reveals no statistically significant differences in qualitative and quantitative parameters. Analysis of the effect of age showed that the range of motion decreases significantly (p < 0.01) with increasing age. In lateral bending, the ratio between axial rotation and lateral bending increases significantly (p < 0.01) among older subjects. Differences in acceleration, jerk and polynomial fit are seen between the age categories, but are not significant. INTERPRETATION: This study demonstrates no significant differences in kinematic parameters between healthy subjects and subjects with non-specific neck pain. Healthy subjects in higher age categories demonstrate higher ratios of coupled movements and lower ranges of motion. Future research should focus on classifying patients with non-specific neck pain in order to gain a better insight on possible subgroup specific differences in kinematics. More studies on this subject are warranted. LEVEL OF EVIDENCE: 4.

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.

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.

Direct measurement of tibial cortical bone surface area.

Cortical bone surface area estimation is generally performed by analysis of medical images but its accuracy has not yet been verified by direct bone measurements. This study was performed to evaluate the reproducibility of direct ex vivo estimations of cross sectional tibial cortical bone surface area. Ten tibiae were evaluated by two observers using direct 3D-digitization at 38 and 66% of total tibial length using a 'critical' and a 'general' criterion for differentiation between cortical and cancellous bone. The results of the analysis using the more severe 'critical' differentiation criterion yielded high intra and interobserver agreement. Mean intraobserver reliability was demonstrated by R = 0.98 (Spearman rank correlation between 0.98 and 0.97; P < 0.01) and inter observer reliability by R = 0.91 (Spearman rank correlation between 0.95 and 0.88; P < 0.01). When using strict criteria to differentiate between cortical and cancellous bone, intra and interobserver reliability of the presented method of direct cortical bone surface area estimation is very high. The results indicate that cross-sectional cortical bone surface estimation by direct 3D-digitization can serve as a gold standard for validation of other estimations methods.

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.

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.

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.

Anthropometric fractionation of body mass: Matiegka revisited.

In a group of 699 Belgian nursing professionals, we estimated body composition using the four-component anthropometric model, relying on the equations originally formulated by Matiegka in 1921 and later revised by Drinkwater and colleagues. We estimated muscle mass using the more recent formula proposed by Martin and co-workers. A discrepancy was noted between estimated total body mass and 'assessed' mass, suggesting erroneous estimations of the components.

Observation of a supernumerary hamstring muscle: a state of the art on its incidence and clinical relevance.

During routine anatomic dissection of the lower extremities of a 67-year-old male body, a supernumerary ishiocrural muscle was observed. This supernumerary muscle had similarities to a rare variant of the semimembranous muscle. On the left side it arose from the lateral dorsal side of the femur between the short head of the biceps femoris muscle and the origin of the adductor magnus muscle. It inserted on the medial condyle deep to the normal insertion of the semimembranous at the posterior aspect of the articular capsule. This muscle can be regarded either as a short deep semimembranous muscle (M. semimembranosus profondus) or as a short belly of a semitendinous biceps as known in birds. The muscle was situated closely to the vessels and nerves of the popliteal region. On the right side a similar but somewhat fainter muscle was observed whose origin emanated from the fascia of the adductor magnus muscle. The muscle probably has no major clinical importance but might be important to the surgeon who has to intervene in the popliteal region.

Will the use of different prevalence rates influence the development of a primary prevention programme for low-back problems?

To determine relations to low-back problems (LBP), different prevalence rates are used. The disadvantage of using different selection criteria is that studies are not comparable, except where they provide the same results. The present aim was to establish whether different prevalence selection criteria lead to different answers on a newly formed set of questionnaires. Since this set is new, reliability tests were performed (test-retest and calculations of Cronbach's Alpha, Cohen's Kappa and the intraclass correlation). Results of the questionnaire should form the cornerstones of a primary prevention programme. Altogether 1783 nurses in four Flemish (Belgian) hospitals were questioned. Information was gathered on work circumstances, education, general health, psychosocial factors, leisure activities, family situation and musculoskeletal problems. Four different datasets with variables related to lifetime prevalence LBP, annual prevalence LBP, point prevalence LBP and a set with all related variables were constructed. The variables demonstrating a relation with LBP differed slightly depending on the kind of prevalence used (lifetime, annual, point). A factor analysis on each set of prevalence related data failed due to the lack of homogeneity of the variables. Fear avoidance, coping aspects and musculoskeletal problems in other regions then the lower back were, in all circumstances, the most discriminating variables. Their discriminating power, however, differed depending on the kind of prevalence used. The differences were too small to influence the construction of the prevention programme. It is concluded that in developing a primary prevention programme any of the prevalence rates can be used. The combination of the three types of prevalence rates studied provides the most complete and reliable image.

Upper cervical instability: are clinical tests reliable?

SUMMARY. The aim of this preliminary study was to investigate the reliability of a selection of manual tests used for the examination of instability of the upper cervical region. Eleven children with Down's syndrome were examined by four independent examiners with different levels of experience in manual therapy. Three tests as described by Van der El (1992) were used: the lateral displacement test, the Sharp-Purser test, and the upper cervical flexion test. Scores of tests and retests were statistically analysed by calculating the percentage of agreement, and Brennan and Prediger's modified kappa, and with the binomial test. The results showed a significant agreement between test and retest for the upper cervical flexion test in three out of four investigators. Agreement between investigators was significant in four out of six combinations between two investigators, and near to significant for this test (P(bin) =.07) in the two remaining combinations. The other two investigated tests and the total score showed no tendancy towards a consistent level of significant intra- or interobserver reliability. Copyright 1997 Harcourt Publishers Ltd.