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.

Prediction of the drilling path to surgically pin the femoral neck from the spatial location of pelvic and femoral anatomical landmarks: A cadaver validation study

Several clinical applications rely on accurate guiding information when drilling along the femoral neck (e.g., pin insertion in case of neck fracture). Currently, applications rely on real-time X-ray imaging, which results in irradiation issues for the surgeon conducting the operation. The goal of this paper was to develop an X-ray-free method that would allow for a pathway to be drilled between the lateral aspect of the femoral diaphysis (the so-called piercing point), the femoral neck and the head centres. The method is based on on-the-fly computational predictions relying on a biomechanical database that includes morphological data related to the femoral neck and head and various palpable anatomical landmarks located on the pelvis and the femoral bone. From the spatial location of the anatomical landmarks, scalable multiple regressions allow for the prediction of the most optimal drilling pathway. The method has been entirely validated using in vitro experiments that reproduce surgical conditions. Further, a surgical ancillary prototype that integrates the method of guiding the pin drilling has been developed and used during in vitro and in situ validation using nine hip joints. Pin insertion was controlled after drilling using medical imaging and show successful result for each of the nine trials. The mean accuracy of the estimated hip joint centre and neck orientation was 6.0 ± 2.8mm and 7.1 ± 3.8°, respectively.

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.

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.

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.

Tendon and fascial structure contributions to knee muscle excursions and knee joint displacement

BACKGROUND

Semitendinosus and gracilis muscles whose tendons are used in surgical reconstruction of the anterior cruciate ligament maintain their contractile ability, and a limited decrease of hamstring muscles force is observed postoperatively despite important changes. The goal was to quantify the influence of the myofascial structures on excursions and moment arms of knee muscles to attempt explaining the above-mentioned post-surgical observations.

METHODS

Hamstring harvesting procedures were performed by a senior orthopaedic surgeon on seven lower limbs from fresh-frozen specimens. Femoro-tibial kinematics and tendons excursion were simultaneously recorded at each steps of the surgery.

FINDINGS

No significant difference was demonstrated for excursions and moment arms after tenotomies and gracilis tendon harvesting (P≥0.05). The first significant semitendinosus excursion (P<1.17×10(-4)) and moment arm (P<6.88×10(-5)) decrease was observed after semitendinosus tendon harvesting (46% of the initial excursion).

INTERPRETATION

Gracilis and semitendinosus myofascial pathway is crucial for force transmission towards the knee joint.

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.

Determination of the precision and accuracy of morphological measurements using the Kinect™ sensor: comparison with standard stereophotogrammetry

The recent availability of the Kinect™ sensor, a low-cost Markerless Motion Capture (MMC) system, could give new and interesting insights into ergonomics (e.g. the creation of a morphological database). Extensive validation of this system is still missing. The aim of the study was to determine if the Kinect™ sensor can be used as an easy, cheap and fast tool to conduct morphology estimation. A total of 48 subjects were analysed using MMC. Results were compared with measurements obtained from a high-resolution stereophotogrammetric system, a marker-based system (MBS). Differences between MMC and MBS were found; however, these differences were systematically correlated and enabled regression equations to be obtained to correct MMC results. After correction, final results were in agreement with MBS data (p = 0.99). Results show that measurements were reproducible and precise after applying regression equations. Kinect™ sensors-based systems therefore seem to be suitable for use as fast and reliable tools to estimate morphology. Practitioner Summary: The Kinect™ sensor could eventually be used for fast morphology estimation as a body scanner. This paper presents an extensive validation of this device for anthropometric measurements in comparison to manual measurements and stereophotogrammetric devices. The accuracy is dependent on the segment studied but the reproducibility is excellent.

Validity and reliability of the Kinect within functional assessment activities: comparison with standard stereophotogrammetry

The recent availability of the Kinect™ sensor, a cost-effective markerless motion capture system (MLS), offers interesting possibilities in clinical functional analysis and rehabilitation. However, neither validity nor reproducibility of this device is known yet. These two parameters were evaluated in this study. Forty-eight volunteers performed shoulder abduction, elbow flexion, hip abduction and knee flexion motions; the same protocol was repeated one week later to evaluate reproducibility. Movements were simultaneously recorded by the Kinect (with Microsoft Kinect SDK v.1.5) MLS and a traditional marker-based stereophotogrammetry system (MBS). Considering the MBS as reference, discrepancies between MLS and MBS were evaluated by comparing the range of motion (ROM) between both systems. MLS reproducibility was found to be statistically similar to MBS results for the four exercises. Measured ROMs however were found different between the systems.

A wearable inertial system to assess the cervical spine mobility: comparison with an optoelectronic-based motion capture evaluation

In clinical settings, the cervical range of motion (ROM) is commonly used to assess cervical spine function. This study aimed at assessing cervical spine mobility based on head and thorax kinematics measured with a wearable inertial system (WS). Sequences of imposed active head movements (lateral bending, axial rotation and flexion-extension) were recorded in ten controls and 13 patients who had undergone an arthrodesis. Orientation of the head relative to the thorax was computed in terms of 3D helical angles and compared with the values obtained using an optoelectronic reference system (RS). Movement patterns from WS and RS showed excellent concurrent validity (CMC up to 1.00), but presented slight differences of bias (mean bias<2.5°) and dispersion (mean dispersion<4.2°). ROM obtained using WS also showed some differences compared to RS (mean difference<5.7°), within the range of those reported in literature. WS enabled the observation of the same significant differences between controls and patients as RS. Moreover, ROM from WS presented good test-retest repeatability (ICC between 0.63 and 0.99 and SEM<6.2°). In conclusion, WS can provide angles and ROM comparable to those obtained with RS and relevant for the cervical assessment after treatment.

Objective evaluation of cervical spine mobility after surgery during free-living activity

BACKGROUND

Evaluation of cervical spine mobility after surgery is mainly based on the measurement of the range of motion during imposed movements. It can thus be questionable if this assessment represents the mobility experienced during daily life. The goal of this study was to propose a new evaluation tool based on the monitoring of cervical spine movement during daily activities.

METHODS

The detection of cervical movement and the determination of primary motion component (lateral bending, axial rotation or flexion-extension), using two inertial sensors, were first validated in laboratory settings. Fifteen patients who underwent a cervical arthrodesis and nine healthy control subjects were monitored during their daily activity for half a day. The frequency of cervical movement was quantified according to posture, i.e. static and walking periods. The amplitude and velocity of cervical movement were evaluated using the median and cumulative distribution function.

FINDINGS

The movement detection and classification showed an excellent performance (sensitivity and specificity>94%). For the daily monitoring, the patients presented a movement frequency similar to controls, whereas the amplitude and velocity in patients were lower than in controls (P<0.05). The differences between patients and controls were larger for the velocity parameters (effect sizes>0.37 and >0.54 for static and walking periods respectively) than for the amplitude parameters.

INTERPRETATION

Body-worn inertial sensors enable the quantitative evaluation of global cervical movement. The movement amplitude and velocity during free-living conditions can be used as objective parameters to evaluate the cervical spine mobility after treatment.

[Clinical examination of children with cerebral palsy: is there a consensus between clinicians?]

Diagnosis and most of all classification of children with cerebral palsy (CP) remain a challenge for clinicians. To help them in this process, clinicians can rely on several clinical testing procedures as well as complementary investigations. The goal of this study was to determine which clinical tests found in the literature are the most frequently used in common practice in Belgium. Forty tests have been found in the literature. They have been sorted into five different categories: quantitative evaluation of motor function, spasticity evaluation, orthopaedic testing, upper limb evaluation and complementary investigations. Seven clinicians (five medical doctors and two physiotherapists) with a mean experience of sixteen years with CP children answered the questionnaire. Concerning the quantitative evaluation of motor function the most used tests are: Gross Motor Function Classification System, Manual Ability Classification System and the Pediatric Evaluation of Disability Inventory (PEDI). As regards spasticity, Ashworth scale is more frequently used than Tardieu test. No trend currently exist for the upper limb evaluation, but it was noted that these tests are rarely used in clinical practice. We observed a significant use of gait analysis at diagnosis and follow-up of CP children. We conclude that there are large differences between clinicians for clinical examination of CP children. This lack of consensus makes patient data comparison difficult between clinical centers. This seems to indicate that a homogenization effort should be organized if one wishes to better stimulate collaborations between centers.

In vitro biomechanical study of femoral torsion disorders: effect on moment arms of thigh muscles

BACKGROUND

Lower limb torsion disorders have been considered as a factor inducing gonarthrosis and the three-dimensional effect of the surgical correction is not well reported yet. This paper reports an in vitro study aiming at quantifying the relationships between experimental femoral torsion disorders and moment arms of thigh muscles.

METHODS

Five unembalmed lower limbs were used and fixed on an experimental jig. Muscles were loaded and 6 Linear Variable Differential Transformers were used to measure tendon excursions. Experimental osteotomies were performed to simulate torsions by steps of 6° up to 18°. Moment arms of the main thigh muscles were estimated by the tendon excursion method during knee flexion.

FINDINGS

Moment arms of the tensor of fascia latae, the gracilis and the semitendinosus were significantly influenced by experimental conditions while the rectus femoris, the biceps femoris and the semimembranosus did not show modifications. Medial femoral torsion decreased the moment arm of both the gracilis and the semimembranosus. Opposite changes were observed during lateral femoral torsion. The moment arm of the tensor of fascia latae decreased significantly after 30° of knee flexion for 18° of medial femoral torsion.

INTERPRETATION

Our results showed that medial and lateral femoral torsion disorders induced alterations of the moment arms of the muscles located medially to the knee joint when applied in aligned lower limbs. These results highlight a potential clinical relevance of the effect of femoral torsion alterations on moment arms of muscles of the thigh which may be related, with knee kinematics modifications, to the development of long-term knee disease.

In vitro biomechanical study of femoral torsion disorders: effect on femoro-tibial kinematics

BACKGROUND

Gonarthrosis is a degenerative disease mainly found in elderly persons. Frontal plane deviations are known to induce lateral and medial gonarthrosis. Nevertheless, patients suffer from gonarthrosis without frontal deviations. Lower limb torsions disorders have been considered as a factor inducing lateral and medial gonarthrosis. This paper reports an in vitro study aiming at quantifying the relationships between experimental femoral torsion disorders and femoro-tibial kinematics.

METHODS

Five fresh-frozen lower limbs were used. Specimens were fixed on an experimental jig and muscles were loaded. A six-degree-of-freedom Instrumented Spatial Linkage was used to measure femoro-tibial kinematics. Experimental femoral osteotomies were performed to simulate various degrees of medial and lateral torsion. Internal tibial rotation, abduction/adduction and proximo-distal, medio-lateral and antero-posterior translations were measured during knee flexion.

FINDINGS

Internal tibial rotation and abduction/adduction were significantly influenced (P<0.001) by femoral torsion disorder conditions. Medial femoral torsion increased tibial adduction and decreased internal rotation during knee flexion. Opposite changes were observed during lateral femoral torsion. Concerning translations, medial femoral torsion induced a significant (P<0.05) decrease of medial translation and inversely for lateral femoral torsion. No interactions between femoral torsion disorders and range of motion were observed.

INTERPRETATION

Our results showed that medial and lateral femoral torsion disorders induced alterations of femoro-tibial kinematics when applied in normally aligned lower limbs. These results highlight a potential clinical relevance of the effect of femoral torsion alterations on knee kinematics that may be related to the development of long-term knee disease.

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.

Effects of proximal row carpectomy on wrist biomechanics: a cadaveric study

BACKGROUND

Many studies show good clinical results after proximal row carpectomy. Some biomechanical consequences are documented, but to our knowledge muscle moment arm variations have not previously been quantified.

METHODS

In five fresh-frozen wrist, kinematics and tendon excursions were measured using a 3D electrogoniometer and Linear Variable Differential Transformers (SOLARTRON Inc., AMETEK Advanced Measurement Technology, Inc, 801 South Illinois Avenue, Oak Ridge, TN 37831-2011, USA), respectively, in three conditions: intact wrist, after posterior capsulotomy and after proximal row carpectomy. Mean pivot point, defined as the point whose sum of the squared distances to the helical axes is minimum, wrist range of motion and mean moment arms were measured during dorso-palmar flexion, radioulnar deviation and circumduction movements.

FINDINGS

No alteration of the range of motion was observed. On the other hand, the mean pivot point shifted proximally (6.8-9.1mm) after proximal row carpectomy (p<0.05) for all motions tested and most muscle moment arms decreased significantly after proximal row carpectomy.

INTERPRETATION

The results of this study allow a better understanding of the biomechanical effects of this procedure. The important moment arm reduction and pivot point displacement suggest modifications of joint biomechanical parameters which could influence the functional outcome of PRC.

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.

[The first Belgian hand transplantation case. Nine years follow-up]

The authors report the clinical result at 9 years followup of a unilateral hand transplantation performed on the dominant side after traumatic forearm amputation. The patient is back to work and sporting activities. The allograft has been fully incorporated into his self-image. The satisfaction index is 10/10, the DASH 5/100, and the 400-points score 68.1 %. The Lanzetta HTSS score is 91 (excellent). Good function of extrinsic and intrinsic muscles is observed. The grasping strength is markedly decreased (7.4 % as compared to the normal non-dominant side). The patient has experienced several rejection episodes, controlled by the immunosuppressant drugs.

[Reconstruction of the knee anterior cruciate ligament: single or double bundle?]

Anatomical and biomechanical studies have shown that the anterior cruciate ligament (ACL) consists of two distinct bundles, the anteromedial (AM) and posterolateral. Each bundle has its specific role during the motion of the knee. ACL reconstruction techniques have focused on the restauration of the anteroposterior stability by substituting the more isometric AM bundle. Although these ligamentoplasties provide overall good results, in the last ten years double-bundle ACL reconstruction techniques have been developed, to better replicate the ligament anatomy. Despite the growing number of published studies, including randomized controlled trials comparing single bundle and double bundle reconstructions, there is still a lack of evidence of any superiority of the double-bundle technique. Furthermore, many series are criticized for their poor assessement of rotational stability, using most of the time subjective pivot shift clinical testing. Among the methods available to measure tibial rotation, 3-D optoelectronic evaluation is an attractive tool and has been used in some studies reporting rotational mesurements after ACL single-bundle reconstruction. Our Department of Orthopaedics and Traumatology has been using double-bundle techniques for a few years. We conducted a preliminary prospective randomized study, in order to compare single and double-bundle techniques by clinical and optoelectronic evaluations.

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.

Precision of shoulder anatomical landmark calibration by two approaches: a CAST-like protocol and a new anatomical palpator method

The objective of the study was to compare the precision of shoulder anatomical landmark palpation using a CAST-like method and a newly developed anatomical palpator device (called A-Palp) using the forefinger pulp directly. The repeated-measures experimental design included four examiners that twice repeated measurements on eleven scapula and humerus anatomical landmarks during two sessions. Inter-session and inter-examiner precision was determined on volunteers. A-Palp accuracy was obtained from in vitro measurements and using virtual palpation on 3D bone models. Error propagation on the motion representation was also analyzed for a continuous motion of abduction movement performed in the shoulder joint. Palpation results showed that CAST and A-Palp methods lead to similar precision with the Maximal A-Palp calibration error being 1.5mm. In vivo precision of the CAST and A-Palp methods varied between 4mm (inter-session) and 8mm (inter-examiner). Mean propagation of the palpation error on the motion graph representation was 2 degrees and 5 degrees for scapula and humerus, respectively. A-Palp accuracy was 3.6 and 8.1mm for scapula and humerus, respectively. The A-Palp seems promising and could probably become an additional method next to today's marker-based motion analysis systems (i.e., Helen-Hayes configuration, CAST method).

[Geldanamycin administration reduces the number of HSP86-positive germ cells in the mouse embryo: preliminary results]

5 mg of Geldanamycin, an inhibitor of stress protein HSP86 which express on mammalian germ cells, were administered to E8 pregnant mice. E17 embryos were removed, and a quantitative analysis of HSP90-immunoreactive cells in the gonad was performed, in comparison to control embryos. First, we observed that the number of germ cells is lower in male than in female embryos, as well in control and experimental embryos. External features of experimental and control embryos did not display any difference. Embryos exposed to geldanamycin exhibit a significant decrease of immunoreactive germ cells. In two embryos, we observed a group of ectopic immunoreactive cells in the pelvic area. We conclude that geldanamycin inhibits germ cells migration, and suggest that this inhibition can lead to ectopic germ cell populations, similar to teratomas.

Prediction of joint center location by customizable multiple regressions: application to clavicle, scapula and humerus

Accurate spatial location of joint center (JC) is a key issue in motion analysis since JC locations are used to define standardized anatomical frames, in which results are represented. Accurate and reproducible JC location is important for data comparison and data exchange. This paper presents a method for JC locations based on the multiple regression algorithms without preliminary assumption on the behavior of the joint-of-interest. Regression equations were obtained from manually palpable ALs on each bone-of-interest. Results are presented for all joint surfaces found on the clavicle, scapula and humeral bone. Mean accuracy errors on the JC locations obtained on dry bones were 5.2+/-2.5 mm for the humeral head, 2.5+/-1.1 mm for the humeral trochlea, 2.3+/-0.9 mm for the humeral capitulum, 8.2+/-3.9 mm for the scapula glenoid cavity, 7.2+/-3.2 mm for the scapular aspect of the acromio-clavicular joint, 3.5+/-1.8mm for the clavicular aspect of the sternoclavicular joint and 3.2+/-1.4 mm for the clavicular aspect of the acromio-clavicular joint. In-vitro and in-vivo validation accuracy was 5.3 and 8.5mm, respectively, for the humeral head center location. Regression coefficients for joint radius dimension and joint surface orientation were also processed and reported in this paper.

[Learning strategies and anatomy teaching in the Pôle Universitaire Européen Bruxelles-Wallonie]

In order to compare the learning strategies associated to human anatomy courses in student of first, second and third year in medicine, first year in medical biology technologists and first year in nursing, we distributed a questionnaire to the students. The results revealed some similarities, but also several differences, in relationship with local conditions, the content of the courses, and specificities of different student groups, especially in their study choice. Paradoxically, the integration of medical imaging in medical students seems to be difficult, and the medical students are reticent to use another body to ingrate anatomy, although surface anatomy constitutes a part of the anatomical program. This restriction is absent in nursing. These results constitute important data in the field of cognitive research, but also should be useful to improve our pedagogic strategy in specific populations.

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.

Modifications de la cinématique du genou et des bras de levier du quadriceps et des ischio-jambiers après ostéotomie tibiale haute « curviplane » de valgisation ou de varisation

PURPOSE OF THE STUDY

Analysis of the correction or over-correction of high valgus and varus tibial osteotomies is generally limited to the frontal plane. Most likely however, the deformation observed radiographically in the frontal plane is simply a one-dimensional expression of a more complex three-dimensional deformation. This might be one of the causes for certain failures after surgery and recurrent problems which are difficult to solve. We proposed using 3D electrogoniometric to measure of the effect of a "dome" osteotomy on patellar and femoro-tibial kinematics and the changes in the moment arms of the knee muscles.

MATERIAL AND METHODS

We used five lower limbs harvested from non-fixed cadavers. A "dome" osteotomy was stabilized by external fixation. Three-dimensional analysis of the femoro-tibial and femoro-patellar kinematics was performed using two electrogoniometers with six degrees of freedom. Changes in the lengths of the hamstrings and quadriceps was measured using four LVDT linear variable differential transformers. The muscles lever arms were measured with the tendon excursion method.

RESULTS

At 90 degrees flexion, varus osteotomy induced internal rotation while valgus osteotomy induced the opposite effect. Beyond 40 degrees flexion, there was a clear internal rotation of the patella for varus and neutral corrections. Valgus corrections however induced external rotation. The peak lever arm of the quadriceps increased with valgus, while the angle of the peak was higher for varus correction. Valgus appeared to increase the lever arm of the semitendinous.

DISCUSSION

Our study demonstrated that the effect of tibial osteotomy is not limited to the frontal plane. Tibial rotations are observed systematically for all corrections in the frontal plane. Varus correction tends to create internal rotation while valgus correction tends to have the opposite effect. Axial correction also affects patellar kinematics. Interanal rotation is induced by varus correction and external rotation by valgus correction. This patellar rotation could result from tibial rotations induced by the different corrections. The loss of the parallelism between the patellar crest and the trochlear groove could produce changes in femoropatellar surface contact and pressure, potentially leading to pain or cartilage degeneration. The maximal value of the quadriceps moment arm appears to increase with valgus. The efficacy of the quadriceps could thus be improved with valgus, potentially increasing extension force. Valgus increases the moment arm, improving limb flexion, while varus correction has the opposite effect. This could explain a loss in flexion amplitude in patients with varus or who underwent varus osteotomy. Tibial osteotomy is designed to correct the deviation solely in the frontal plane but also has effects in all three planes. Further 3D analyses of the morphology and physiology of the knee joint would be needed to better understand the physiological and pathological processes involved.

Clinical and goniometric evaluation of patients with spasmodic torticollis

BACKGROUND

Patients with cervical dystonia have been evaluated prospectively by the Toronto Western Spasmodic Torticollis Rating Scale and by cervical electrogoniometry.

METHODS

Nineteen patients with cervical dystonia were studied. The Toronto Scale interobserver reliability was evaluated by two observers. An electrogoniometer was used to quantify cervical range of motion and velocity. The correlation between goniometric measurements and clinical evaluation was calculated.

FINDINGS

The interobserver reliability was excellent for the total score (r(s) = 99) and good for the disability and the pain score (r > 0.88). However, global severity scale was shown to have a moderate reliability (r = 0.63) with r ranging from 0.37 to 0.98 for the individual items. The average loss of range of motion for flexion and extension, lateral bending and rotation was 18%, 12% and 21% respectively. For the velocity of movement, the average loss was proportionately greater than for the range of motion. (41%, 43% and 52% respectively). Correlation between the severity scale and range of motion was moderate but significant (r(s) = -0.52 to -0.67). Correlation between the Toronto severity score and the sum of movement velocities was significant for flexion-extension and lateral bending velocity sums (r(s) = -0.51; r(s) = -0.61). The lateral bending and rotation velocities were significantly correlated with pain and total scores (r(s) = -0.51). No significant correlation was observed for the disability score.

INTERPRETATION

Three-dimensional electrogoniometry is helpful to quantify the velocity of neck movements and range of motion in patients with cervical dystonia.

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).

The first Belgian hand transplantation--37 month term results

The first Belgian hand transplant was a 22 year-old man with a traumatic amputation of his dominant hand at the junction of the middle and distal thirds of the forearm. The donor and recipient had three HLA mismatches. The cross-match was negative. The total ischaemic time was slightly over 6 hours. Immunosuppression included antithymocyte globulins at induction and tacrolimus, mycophenolate mofetil and prednisolone as induction and maintenance therapy. There has been no episode of rejection. The only significant complications, except for transient hyperglycaemia, were psychological. At 37 months post-transplantation, the patient has fully incorporated his transplant into his self-image and is back at work. He has good sensibility (two-point discrimination of 6mm at the thumb and index finger pulps), acceptable wrist and finger motion with functioning intrinsic muscles. According to Chen's criteria, the result is good to excellent.

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.

Double-step registration of in vivo stereophotogrammetry with both in vitro 6-DOFs electrogoniometry and CT medical imaging

Standard registration techniques of bone morphology to motion analysis data often lead to unsatisfactory motion simulation because of discrepancies during the location of anatomical landmarks in the datasets. This paper describes an iterative registration method of a three-dimensional (3D) skeletal model with both 6 degrees-of-freedom joint kinematics and standard motion analysis data. The method is demonstrated in this paper on the lower limb. The method includes two steps. A primary registration allowed synchronization of in vitro kinematics of the knee and ankle joints using flexion/extension angles from in vivo gait analysis. Results from primary registration were then improved by a so-called advanced registration, which integrated external constraints obtained from experimental gait pre-knowledge. One cadaver specimen was analyzed to obtain both joint kinematics of knee and ankle joints using 3D electrogoniometry, and 3D bone morphology from medical imaging data. These data were registered with motion analysis data from a volunteer during the execution of locomotor tasks. Computer graphics output was implemented to visualize the results for a motion of sitting on a chair. Final registration results allowed the observation of both in vivo motion data and joint kinematics from the synchronized specimen data. The method improved interpretation of gait analysis data, thanks to the combination of realistic 3D bone models and joint mechanism. This method should be of interest both for research in gait analysis and medical education. Validation of the overall method was performed using RMS of the differences between bone poses estimated after registration and original data from motion analysis.