The biomechanical role of the lacertus fibrosus of the biceps brachii Muscle.

PURPOSE: The lacertus fibrosus (LF) is involved in various surgeries. However, the biomechanical contribution of the LF remains unclear. The aim of this study was to determine the role of the lacertus fibrosus on the elbow and forearm kinematics and on the biceps brachii muscle lever arms. METHODS: This biomechanical study was performed on seven fresh-frozen upper limbs of cadavers. Elbow flexion, forearm supination, and biceps brachii muscle lever arms were analyzed in the intact conditions (I) and after superficial (R) and deep part (R2) of the lacertus fibrosus release, respectively. RESULTS: Elbow flexion shows a significant difference (p < 0.0001) between I, R, R2. Abduction/adduction shows a significant difference between I-R (p < 0.0001) and I-R2 (p < 0.0001). Supination does not show a significant difference in mean maximum amplitude, but between 40 and 70%, there are significant differences. There is a significant mean decrease of lever arm in flexion (28%) and supination (50%) after superficial and deep part of the lacertus fibrosus release. CONCLUSION: The results of this study show that the lacertus fibrosus increases the lever arm during flexion and supination. It limits the flexion and abduction of the elbow and supination of the forearm. Lacertus fibrosus maintains the rhythmicity between the elbow flexion and supination of the forearm. LEVEL OF EVIDENCE: Basic science study, biomechanics.

Three-Corner Arthrodesis (lunate - hamate - capitate) : clinical and kinematical evaluation.

In the absence of prosthetic arthroplasty offering good results for the treatment of wrist osteoarthritis, we studied the arthrodesis of three carpal bones (lunate - hamate - capitate) completed by triquetrum and scaphoid excision in the presence of Scapholunate Advanced Collapse (SLAC) or Scaphoid Nonunion Advanced Collapse (SNAC) stage II or III. Clinical data on eight patients between the ages of 32 and 61 years at an average of 29 months after surgery was analyzed. Seven patients reached fusion with a carpal height ratio of 0.39. These arc of dorsal-palmar flexion (DPF) attended 54° and the arc of radio-ulnar deviation (RUD) 29° using the optoelectronic stereophotogrammetry system. The mean polar radius (R) was 14.5° and the envelope shape coefficient (K) was 1.66. This operation could be considered as an alternative for the treatment of patients suffering of SNAC or SLAC stage II and III. Type of study/level of evidence : Therapeutic IV.

Metatarsal arch deformation and forefoot kinematics during gait in asymptomatic subjects.

This study aimed to investigate both foot arch-shaped architecture and forefoot kinematics during gait. Using a dedicated three-compartment forefoot subdivision, we studied asymptomatic subjects and quantified disorders related to the metatarsal arch. Foot motion and arch shape were measured in 30 healthy subjects with a motion-capture system and force plates. Kinematic results were expressed using a novel model, which anatomically divides the forefoot into three parts. This model integrated the medial longitudinal arch angle and the metatarsal arch height and width. During the first part of stance phase, the medial longitudinal arch flattens and all foot segments move toward dorsiflexion. During terminal stance and preswing phase, medial longitudinal and metatarsal arch restoration was noted with plantarflexion of all segments, an eversion and abduction of the medial forefoot, and an inversion and adduction of the lateral forefoot. Kinematics obtained with the proposed forefoot model corroborates metatarsal arch restoration in late stance. This observation supports the fact that foot architecture is supple until midstance and subsequently creates a rigid lever arm with restored arches to support propulsion. This study's results and methods highlight the potential of the three-compartment model for use in clinical decision-making.

Head-trunk kinematics during high-velocity-low-amplitude manipulation of the cervical spine in asymptomatic subjects: helical axis computation and anatomic motion modeling.

OBJECTIVE: This study aimed to analyze the in vivo 3-dimensional kinematics of the head during cervical manipulation including helical axis (HA) computation and anatomic motion representation. METHODS: Twelve asymptomatic volunteers were included in this study. An osteopathic practitioner performed 1 to 3 manipulations (high-velocity and low-amplitude [HVLA] multiple component technique) of the cervical spine (between C2 and C5) with the patient in the sitting position. During manipulation, head motion was collected using an optoelectronic system and expressed relative to the thorax. Motion data were processed to analyze primary and coupled motions and HA parameters. Anatomic motion representation including HA was obtained. RESULTS: During manipulation, average maximal range of motion was 39° (SD, 6°), 21° (SD, 7°), and 8° (SD, 5°) for lateral bending (LB), axial rotation (AR), and flexion extension, respectively. For the impulse period, magnitude averaged of 8° (SD, 2°), 5° (SD, 2°), and 3° (SD, 2°), for LB, AR, and flexion extension, respectively. Mean impulse velocity was 139°/s (SD, 39°/s). Concerning AR/LB ratios, an average of 0.6 (SD, 0.3) was observed for global motion, premanipulation positioning, and impulse. Mean HA was mostly located ipsilateral to the impulse side and displayed an oblique orientation. CONCLUSION: This study demonstrated limited range of AR during cervical spine manipulation and provided new perspectives for the development of visualization tools, which might be helpful for practitioners and for the analysis of cervical manipulation using HA computation and anatomic representation of motion.

Effect of anatomical landmark perturbation on mean helical axis parameters of in vivo upper costovertebral joints.

The literature concerning quantification of costovertebral joint (CVJ) motion under in vivo conditions is scarce. Most papers concerning this topic are related to ex vivo loading conditions. In vivo protocols are available from the literature to determine rib and vertebra kinematics but new developments are needed to improve data processing concerning CVJ behaviour obtained from discrete breathing positions showing limiting ranges-of-motion and sensitive to noise. Data from previous work were used to implement a method analyzing mean helical axis (MHA) and pivot point parameters of the CVJ complexes. Several levels of noises were estimated within Monte-Carlo simulations to optimize MHA results. MHA parameters were then used to transform and define a CVJ-specific local coordinate system. This study proposes an improvement for CVJ kinematics processing and description from in vivo data obtained from computed tomography. This methodology emphasizes the possibility to work with variability of MHA parameters using Monte-Carlo procedures on anatomical landmark coordinates and to define a local coordinate system from this particular joint behaviour. Results from the CVJ joint model are closer to a hinge joint (secondary motions inferior to 3°) when anatomical frames are expressed from MHA orientation. MHA orientation and position data obtained from the proposed method are relevant according to angular dispersion obtained (from 7.5° to 13.9°) and therefore relevant to define behaviour of CVJ.

Physiologically corrected coupled motion during gait analysis using a model-based approach.

Gait analysis is used in daily clinics for patients' evaluation and follow-up. Stereophotogrammetric devices are the most used tool to perform these analyses. Although these devices are accurate results must be analyzed carefully due to relatively poor reproducibility. One of the major issues is related to skin displacement artifacts. Motion representation is recognized reliable for the main plane of motion displacement, but secondary motions, or combined, are less reliable because of the above artifacts. Model-based approach (MBA) combining accurate joint kinematics and motion data was previously developed based on a double-step registration method. This study presents an extensive validation of this MBA method by comparing results with a conventional motion representation model. Thirty five healthy subjects participated to this study. Gait motion data were obtained from a stereophotogrammetric system. Plug-in Gait model (PiG) and MBA were applied to raw data, results were then compared. Range-of-motion, were computed for pelvis, hip, knee and ankle joints. Differences between PiG and MBA were then computed. Paired-sample t-tests were used to compare both methods. Normalized root-mean square errors were also computed. Shapes of the curves were compared using coefficient of multiple correlations. The MBA and PiG approaches shows similar results for the main plane of motion displacement but statistically significative discrepancies appear for the combined motions. MBA appear to be usable in applications (such as musculoskeletal modeling) requesting better approximations of the joints-of-interest thanks to the integration of validated joint mechanisms.

Global and regional kinematics of the cervical spine during upper cervical spine manipulation: a reliability analysis of 3D motion data.

Studies reporting spine kinematics during cervical manipulation are usually related to continuous global head-trunk motion or discrete angular displacements for pre-positioning. To date, segmental data analyzing continuous kinematics of cervical manipulation is lacking. The objective of this study was to investigate upper cervical spine (UCS) manipulation in vitro. This paper reports an inter- and intra-rater reliability analysis of kinematics during high velocity low amplitude manipulation of the UCS. Integration of kinematics into specific-subject 3D models has been processed as well for providing anatomical motion representation during thrust manipulation. Three unembalmed specimens were included in the study. Restricted dissection was realized to attach technical clusters to each bone of interest (skull, C1-C4 and sternum). During manipulation, bone motion data was computed using an optoelectronic system. The reliability of manipulation kinematics was assessed for three experimented practitioners performing two trials of 3 repetitions on two separate days. During UCS manipulation, average global head-trunk motion ROM (±SD) were 14 ± 5°, 35 ± 7° and 14 ± 8° for lateral bending, axial rotation and flexion-extension, respectively. For regional ROM (C0-C2), amplitudes were 10 ± 5°, 30 ± 5° and 16 ± 4° for the same respective motions. Concerning the reliability, mean RMS ranged from 1° to 4° and from 3° to 6° for intra- and inter-rater comparisons, respectively. The present results confirm the limited angular displacement during manipulation either for global head-trunk or for UCS motion components, especially for axial rotation. Additionally, kinematics variability was low confirming intra- and inter-practitioners consistency of UCS manipulation achievement.

Kinematics of the upper cervical spine during high velocity-low amplitude manipulation. Analysis of intra- and inter-operator reliability for pre-manipulation positioning and impulse displacements.

To date, kinematics data analyzing continuous 3D motion of upper cervical spine (UCS) manipulation is lacking. This in vitro study aims at investigating inter- and intra-operator reliability of kinematics during high velocity low amplitude manipulation of the UCS. Three fresh specimens were used. Restricted dissection was realized to attach technical clusters to each bone (skull to C2). Motion data was obtained using an optoelectronic system during manipulation. Kinematics data were integrated into specific-subject 3D models to provide anatomical motion representation during thrust manipulation. The reliability of manipulation kinematics was assessed for three practitioners performing two sessions of three repetitions on two separate days. For pre-manipulation positioning, average UCS ROM (SD) were 10° (5°), 22° (5°) and 14° (4°) for lateral bending, axial rotation and flexion-extension, respectively. For the impulse phase, average axial rotation magnitude ranged from 7° to 12°. Reliability analysis showed average RMS up to 8° for pre-manipulation positioning and up to 5° for the impulse phase. As compared to physiological ROM, this study supports the limited angular displacement during manipulation for UCS motion components, especially for axial rotation. Kinematics reliability confirms intra- and inter-operator consistency although pre-manipulation positioning reliability is slightly lower between practitioners and sessions.

A portable system for foot biomechanical analysis during gait.

Modeling the foot is challenging due to its complex structure compared to most other body segments. To analyze the biomechanics of the foot, portable devices have been designed to allow measurement of temporal, spatial, and pedobarographic parameters. The goal of this study was to design and evaluate a portable system for kinematic and dynamic analysis of the foot during gait. This device consisted of a force plate synchronized with four cameras and integrated into a walkway. The complete system can be packaged for transportation. First, the measurement system was assessed using reference objects to evaluate accuracy and precision. Second, nine healthy participants were assessed during gait trials using both the portable and Vicon systems (coupled with a force plate). The ankle and metatarsophalangeal (MP) joint angles and moments were computed, as well as the ground reaction force (GRF). The intra- and inter-subject variability was analyzed for both systems, as well as the inter-system variation. The accuracy and precision were, respectively 0.4 mm and 0.4 mm for linear values and 0.5° and 0.6° for angular values. The variability of the portable and Vicon systems were similar (i.e., the inter-system variability never exceeded 2.1°, 0.081 Nmkg(-1) and 0.267 Nkg(-1) for the angles, moments and GRF, respectively). The inter-system differences were less than the inter-subject variability and similar to the intra-subject variability. Consequently, the portable system was considered satisfactory for biomechanical analysis of the foot, outside of a motion analysis laboratory.

Influence of movement speed on cervical range of motion.

PURPOSE: Cervical range of motion (RoM) has been the subject of many studies. However, only very few of these studies have considered the influence of movement execution speed on the cervical kinematics. The aim of this study is to evaluate the influence of movement speed on cervical RoM. METHOD: Cervical RoM was recorded using an optoelectronic system; 32 healthy subjects performed movements in two modes: the best possible and as fast as possible. OUTCOME MEASURES: The primary movements (flexion-extension, lateral bending, axial rotation) and coupled movements were studied. Paired Student's tests were performed to compare the two modes of movement. RESULTS: The results showed that cervical RoM differed significantly between movement speeds. Amplitudes were higher for each movement (p < 0.001 for flexion-extension, p < 0.001 for lateral flexion, p = 0.008 for axial rotations) when movements were performed as quickly as possible. The range of movements carried out the best possible reached only 95% of those during movements carried out as fast as possible. Concerning coupled movements, an increase in rotational movements coupled to lateral flexion during fast movements was observed. CONCLUSION: The range of motion reported in the literature corresponds to movement carried out in a mode resembling the best possible of our study. Movements made as quickly as possible can display larger motion ranges.

[A technological platform for cerebral palsy - the ICT4Rehab project]. / Une plate-forme technologique liée à la paralysie cérébrale - le projet ICT4Rehab.

The musculoskeletal system (MSS) is essential to allow us performing every-day tasks, being able to have a professional life or developing social interactions with our entourage. MSS pathologies have a significant impact on our daily life. It is therefore not surprising to find MSS-related health problems at the top of global statistics on professional absenteeism or societal health costs. The MSS is also involved in central nervous conditions, such as cerebral palsy (CP). Such conditions show complex etiology that complicates the interpretation of the observable clinical signs and the establishment of a wide consensus on the best practices to adopt for clinical monitoring and patient follow-up. These elements justify the organization of fundamental and applied research projects aiming to develop new methods to help clinicians to cope with the complexity of some MSS disorders. The ICT4Rehab project (www.ict4rehab.org) developed an integrated platform providing tools that enable easier management and visualization of clinical information related to the MSS of CP patients. This platform is opened to every interested clinical centre.

Effect of ankle-foot orthoses on trunk sway and lower limb intersegmental coordination in children with bilateral cerebral palsy.

INTRODUCTION: Ankle-foot orthoses may significantly improve lower limb kinematics in the gait of children with cerebral palsy. Here we aimed to analyze the effect of ankle-foot orthoses on trunk postural control and lower limb intersegmental coordination in children with mild spastic diplegia (GMFCS I or II). METHODS: We recorded tridimensional trunk kinematics and thigh, shank, and foot elevation angles in 20 4-12 year-old children born preterm with spastic diplegia and 20 typically developing children while walking either barefoot or with ankle-foot orthoses. RESULTS: We found significantly greater trunk excursions in children with cerebral palsy compared to typically developing children in both conditions. When wearing ankle-foot orthoses cerebral palsy children showed increased trunk frontal angular velocity. No significant changes in trunk displacement and angular velocity were recorded in the sagittal plane in either group. Typically developing children wearing orthoses showed increased trunk frontal displacement. Wearing orthoses induced significant changes in shank and foot elevation in both groups. CONCLUSION: Ankle-foot orthoses affect postural control and intersegmental coordination in children with cerebral palsy. This should be taken into account when planning therapeutic management.

Use of embedded strain gages for the in-vitro study of proximal tibial cancellous bone deformation during knee flexion-extension movement: development, reproducibility and preliminary results of feasibility after frontal low femoral osteotomy.

BACKGROUND: This paper reports the development of an in-vitro technique allowing quantification of relative (not absolute) deformations measured at the level of the cancellous bone of the tibial proximal epiphysis (CB(TPE)) during knee flexion-extension. This method has been developed to allow a future study of the effects of low femoral osteotomies consequence on the CB(TPE). METHODS: Six strain gages were encapsulated in an epoxy resin solution to form, after resin polymerisation, six measurement elements (ME). The latter were inserted into the CB(TPE) of six unembalmed specimens, just below the tibial plateau. Knee motion data were collected by three-dimensional (3D) electrogoniometry during several cycles of knee flexion-extension. Intra- and inter-observer reproducibility was estimated on one specimen for all MEs. Intra-specimen repeatability was calculated to determine specimen's variability and the error of measurement. A varum and valgum chirurgical procedure was realised on another specimen to observed CB(TPE) deformation after these kind of procedure. RESULTS: Average intra-observer variation of the deformation ranged from 8% to 9% (mean coefficient of variation, MCV) respectively for extension and flexion movement. The coefficient of multiple correlations (CMC) ranged from 0.93 to 0.96 for flexion and extension. No phase shift of maximum strain peaks was observed. Inter-observer MCV averaged 23% and 28% for flexion and extension. The CMC were 0.82 and 0.87 respectively for extension and flexion. For the intra-specimen repeatability, the average of mean RMS difference and the mean ICC were calculated only for flexion movement. The mean RMS variability ranged from 7 to 10% and the mean ICC was 0.98 (0.95-0.99). A Pearson's correlation coefficient was calculated showing that RMS was independent of signal intensity. For the chirurgical procedure, valgum and varum deviation seems be in agree with the frontal misalignment theory. CONCLUSIONS: Results show that the methodology is reproducible within a range of 10%. This method has been developed to allow analysis the indirect reflect of deformation variations in CB(TPE) before and after distal femoral osteotomies. The first results of the valgum and varum deformation show that our methodology allows this kind of measurement and are encourageant for latter studies. It will therefore allow quantification and enhance the understanding of the effects of this kind of surgery on the CB(TPE) loading.

In vitro biomechanical study of femoral torsion disorders: effect on tibial proximal epiphyseal cancellous bone deformation.

PURPOSE: Osteoarthritis (OA) of the knee is a degenerative disease mainly found in elderly population. Valgus deformity seems to be directly related to lateralised gonarthrosis. Contradictory outcomes of surgical series are published in the literature and report satisfactory and unsatisfactory long-term results. Lower limb torsions disorders have been considered as being another factor inducing gonarthrosis. This paper presents an in vitro study aiming at quantifying the relationships between experimental femoral torsion disorders (medial and lateral) and the deformation of the cancellous bone of the proximal tibial epiphysis (CB(TPE)). METHODS: Five left fresh-frozen lower limbs were used. Specimens were mounted on an experimental jig and muscles were loaded. Six measurement elements, including strain gages, were introduced into CB(TPE) to measure relative deformation. Experimental osteotomy control was performed using a specially devised system allowing various amplitudes of medial and lateral torsion. CB(TPE) deformations were measured during knee flexion movement. RESULTS: Intra-observer reproducibility of CB(TPE) deformations showed a mean coefficient of multiple correlation of 0.93 and a mean coefficient of variation of 9% for flexion. Intra-specimen repeatability showed a mean RMS difference ranging from 7 to 10% and a mean ICC of 0.98. CB(TPE) deformations were significantly influenced by femoral torsion disorder conditions and range-of-motion (ROM) for most measurement elements. No interaction between torsion condition and ROM was observed. Globally, CB(TPE) deformation in the lateral compartment increased during experimental lateral torsion disorder simulation and decreased during medial torsion simulation. The opposite behaviour was observed in the medial compartment. The decrease and/or increase were not always proportional to the degree of femoral torsional disorder simulated. CONCLUSION: Experimental results from this study do not fully agree with previously published clinical observations on the femoral torsion disorder. The present quantified results do not support that medial femoral torsion disorder induces an increased lateral tibial deformation, which could be linked to gonarthrosis observed in this compartment. In summary, our results showed that medial and lateral femoral torsion disorder conditions applied in normally aligned lower limb induced a deformation increase in the medial and in the lateral compartment, respectively.

Musculoskeletal modeling of the suboccipital spine: kinematics analysis, muscle lengths, and muscle moment arms during axial rotation and flexion extension.

STUDY DESIGN: In vitro and modeling study of upper cervical spine (UCS) three-dimensional (3D) kinematics and muscle moment arm (MA) during axial rotation (AR) and flexion extension (FE). OBJECTIVE: To create musculoskeletal models with movement simulation including helical axis (HA) and muscle features. SUMMARY OF BACKGROUND DATA: Integration of various kinematics and muscle data into specific-specimen 3D anatomical models with graphical representation of HA and muscle orientation and MA is not reported for the UCS musculoskeletal system. METHODS: Kinematics, anatomical, and computed tomographic imaging data were sampled in 10 anatomical specimens. Using technical markers and anatomical landmarks digitizing, spatial position of segments was computed for five discrete positions of AR and FE using a 3D digitizer. To obtain musculoskeletal model simulation, a registration method was used to combine collected data. Processing was performed using orientation vector and HA computation and suboccipital muscle features (i.e., length and MA) relative to motion angle. RESULTS: Range of motion and coupling were in agreement with previous in vitro studies. HA (i.e., location and orientation) showed low variation at the occipitoaxial and atlantoaxial levels for FE and AR, respectively. The main orientation of the HA was vertical at C1-C2 during AR and horizontal at C0-C1 during FE. For muscles MA, absolute peak value (ranging from 20 to 40 mm) occurred at different poses depending on the analyzed muscle and motion. Poor magnitude was found for obliquus capitis inferior and rectus capitis posterior minor in FE and AR, respectively. CONCLUSION: On the basis of previous methods, we developed a protocol to create UCS musculoskeletal modeling with motion simulation including HA and suboccipital muscles representation. In this study, simultaneous segmental movement displaying with HA and muscles features was shown to be feasible.

In vitro 3D-kinematics of the upper cervical spine: helical axis and simulation for axial rotation and flexion extension.

PURPOSE: Registration of 3D-anatomical model and kinematics data is reported to be an accurate method to provide 3D-joint simulation. We applied this approach to discrete kinematics analysis of upper cervical spine (UCS) during axial rotation (AR) and flexion extension (FE) to create anatomical models with movement simulation including helical axis. METHODS: Kinematics and CT imaging data were sampled in ten anatomical specimens. Using technical and anatomical marker digitizing, spatial position of segments was computed for five discrete positions of AR and FE using a 3D-digitizer. Computerized tomography was used to create anatomical models and to assure kinematics and imaging data registration for simulation. Kinematics was processed using orientation vector and helical axis (HA) computation. RESULTS: Maximal standard error on marker digitizing was 0.47 mm. Range of motion and coupled movement during AR was in agreement with previous in vitro studies. HA location and orientation have shown low variation at the occipitoaxial and atlantoaxial levels for FE and AR, respectively. CONCLUSIONS: We developed a protocol to create UCS anatomical model simulations including three-dimensional discrete kinematics, using previously validated methods. In this study, simultaneous segmental movement simulation and display of HA variations was shown to be feasible. Although partially confirming previous results, helical axis computation showed variations of motion patterns dependent on movement, level and specimen. Further in vivo investigations are needed to confirm relevance of this method in the clinical field.

Neck movement speed in cervical dystonia.

Clinical scales of patients with cervical dystonia do not rate neck movement velocity. We prospectively measured range of neck movements and movement velocities in 35 consecutive patients with cervical dystonia (CD) and 29 normal controls. Reduction of peak velocities in patients with CD was the most robust abnormality and was correlated to TWSTRS. Coupled movements out of attempted movement plane were increased in the patient group. Movement range was moderately though significantly reduced. We conclude that slowing of voluntary neck movements is a frequent and hitherto unrecognized feature in CD.

Low-dose computed tomography: a solution for in vivo medical imaging and accurate patient-specific 3D bone modeling?

BACKGROUND: The number of in vivo clinical biomedical experiments based on computed tomography is increasing. International radiation-protection bodies are promoting the use of low-dose computed tomography to reduce radiation absorption by the subject undergoing imaging. On the other hand no data exist in the literature to quantify whether or not low-dose computed tomography would lead to a decrease of result quality when used for three-dimensional bone modeling and related measurements. METHODS: This paper aimed at finding a consensus between minimal X-ray radiation of the subject, and satisfactory image data quality, especially for accurate three-dimensional bone modeling. Several standard computed tomography and low-dose computed tomography sequences were analyzed in three tests and statistically compared. FINDINGS: Absence of significant difference between standard and low-dose computed sequences indicated that the low-dose setting would not produce less accurate three-dimensional models, while it decreased the effective X-ray dose up to 90% compared to standard settings. INTERPRETATION: Low-dose computed tomography seems suitable for accurate three-dimensional bone modeling, while the related effective X-ray radiation is low. Such setting is therefore advised for any in vivo medical imaging aiming to collect bone data.

In vivo registration of both electrogoniometry and medical imaging: development and application on the ankle joint complex.

An in vivo method for joint kinematics visualization and analysis is described. Low-dose computed tomography allowed three-dimensional joint modeling, and electrogoniometry collected joint kinematic data. Data registration occurred using palpated anatomical landmarks to obtain interactive computer joint simulation. The method was applied on one volunteer's ankle, and reproducibility was tested (maximal discrepancy: 3.6 deg and 5.5 mm for rotation and translation respectively).

Head repositioning accuracy in patients with whiplash-associated disorders.

STUDY DESIGN: Controlled study, measuring head repositioning error (HRE) using an electrogoniometric device. OBJECTIVE: To compare HRE in neutral position, axial rotation and complex postures of patients with whiplash-associated disorders (WAD) to that of control subjects. SUMMARY OF BACKGROUND DATA: The presence of kinesthetic alterations in patients with WAD is controversial. METHODS: In 26 control subjects and 29 patients with WAD (aged 22-74 years), head kinematics was sampled using a 3-dimensional electrogoniometer mounted using a harness and a helmet. All tasks were realized in seated position. The repositioning tasks included neutral repositioning after maximal flexion-extension, eyes open and blindfolded, repositioning at 50 degrees of axial rotation, and repositioning at 50 degrees of axial rotation combined to 20 degrees of ipsilateral bending. The flexion-extension, ipsilateral bending, and axial rotation components of HRE were considered. A multiple-way repeated-measures analysis of variance was used to compare tasks and groups. RESULTS: The WAD group displayed a reduced flexion-extension range (P = 1.9 x 10(-4)), and larger HRE during flexion-extension and repositioning tasks (P = 0.009) than controls. Neither group nor task affected maximal motion velocity. Neutral HRE of the flexion-extension component was larger in blindfolded condition (P = 0.03). Ipsilateral bending and axial rotation HRE components were smaller than the flexion-extension component (P = 7.1 x 10(-23)). For pure rotation repositioning, axial rotation HRE was significantly larger than flexion-extension and ipsilateral bending repositioning error (P = 3.0 x 10(-23)). Ipsilateral bending component of HRE was significantly larger combined tasks than for pure rotation tasks (P = 0.004). CONCLUSIONS: In patients with WAD, range of motion and head repositioning accuracy were reduced. However, the differences were small. Vision suppression and task type influenced HRE.