Anatomical study of paratenons and fascia lata connections in the posteromedial knee region.

INTRODUCTION: In the last decade, fascia research increased significantly in various aspects such as anatomical and biomechanical features related to epimuscular force transmission. METHODS: The present anatomic study focuses on macroscopic observations of the potential gracilis and semitendinosus paratenons, as well as fascial surroundings connections in the posteromedial knee region on 17 lower-limbs dissections. RESULTS: The gracilis and semitendinosus expansions and paratenons were observed in all specimen and further connections with the fascia lata and crural fascia were demonstrated. Contrary to the previously described expansions connected to the tendons, we observed that the expansions were the edges of the paratenon tunnel and that the paratenon structure surrounded the overall muscle. Both paratenons of gracilis and semitendinosus were connected to the crural fascia and, respectively, to the sartorius fascia (part of the fascia lata), to the semimembranosus and the fascia lata. Furthermore, numerous connections between the fascia lata and the neighboring structures in the posteromedial knee region are described. DISCUSSION-CONCLUSION: The present study describes for the first time gracilis and semitendinosus paratenons and other surrounding fascial connections. Such macroscopic observations may represent a new basis for further characterization of the myofascial pathway of epimuscular force transmission in the knee region.

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.

Joint contact areas after radial head arthroplasty: a comparative study of 3 prostheses.

BACKGROUND: Contact stresses of radial head prostheses remain a concern, potentially leading to early capitellar cartilage wear and erosion. In particular, point contact or edge loading could have a detrimental effect. The purpose of this study was to compare 3 different types of radial head prostheses in terms of joint contact areas with each other and with the native situation. The hypothesis was that the joint contact areas would be lower after monopolar arthroplasty. METHODS: Seven fresh-frozen cadaveric upper limbs were used. Radiocapitellar contact areas of a monopolar design, a straight-neck bipolar design, and an angled-neck bipolar design were compared with each other and with the native joint. After standardized preparation, polysiloxane was injected into the loaded radiocapitellar joint to create a cast from which the joint contact area was measured. Measurements were performed at 3 angles of elbow flexion and in 3 different forearm positions. RESULTS: In the native elbow, contact areas were highest in supination. Elbow flexion had no significant effect on native and prosthetic joint contact areas. Contact areas were decreased for all types of arthroplasties compared with the native joint (from 11% to 53%). No significant contact area difference was found between the 3 designs. However, bipolar prostheses showed lateral subluxation in neutral forearm rotation, resulting in a significant decrease in the contact areas from pronation to the neutral position. CONCLUSIONS: All types of radial head prostheses tested showed a significant decrease in radiocapitellar contact area compared with the native joint. Bipolar designs led to subluxation of the radial head, further decreasing radiocapitellar contact.

Pregnancy and pelvic girdle pain: Analysis of pelvic belt on pain.

AIMS AND OBJECTIVES: To analyse pain and functional capacity in women with pelvic girdle pain and to evaluate the effect of pelvic belt on these parameters. Two types of belts were to compare. BACKGROUND: Pelvic girdle pain is very common during pregnancy. To prevent and relieve pelvic pain, women can use a set of techniques and tools such as a pelvic belt. While scientific evidence is lacking, commercial industries suggest the effectiveness of pelvic belts. DESIGN: Randomised control trial. METHODS: Forty-six pregnant women with pelvic girdle pain were evaluated. Pain analysis included a quantitative and a qualitative assessment. A daily activities questionnaire was used for functional capacity evaluation. Women were tested at two times during the pregnancy for a longitudinal evaluation, and they used one of the two belt models during their pregnancy. RESULTS: Pelvic pain started between the 14th-21st week of pregnancy. Pain intensity was 60 ± 20 mm. Daily activities could increase pain. The use of belts reduced pain. The intensity of pain decreased by 20 mm on a visual analogue scale. The daily activities were also easier. However, all these conclusions are valid only if pregnant women used belts regularly on short periods. CONCLUSIONS: The belts appear to be interesting tools to reduce pelvic pain and improve comfort of pregnant women. This effect might be explained by an analgesic effect with proprioceptive and biomechanical effect. The different types of belts could have differential effects on global, sacroiliac joint and back pain during pregnancy, but this hypothesis requires confirmation. RELEVANCE TO CLINICAL PRACTICE: Relevant for patient: to use an easy and validated tool. Relevant for clinical practice: to suggest a tool scientifically validated for patient. Relevant to economic issues: belts decrease pelvic pain and increase comfort of pregnant women. Sick leave could decrease.

The effect of humerus diaphyseal shortening on brachial plexus tension: a cadaver study.

PURPOSE: To assess the extent to which diaphyseal shortening of the humerus can allow direct suture in case of rupture or transection injuries of the brachial plexus. METHODS: The use of 3 fresh cadaver specimens allowed for the study of 6 brachial plexuses. Distance measurements were made between reference points placed on the clavicle and on different parts of the plexus. Those measurements were repeated after shortening the humerus by 2, 4, and 6 cm. RESULTS: None of the dissected plexuses had classic anatomy. A humeral shortening of 6 cm allowed for a statistically significant reduction of length between the supraclavicular part of the plexus and the terminal branches, which did not exceed 17 mm on average. The difference of length was much greater for the specimen in which the musculocutaneous nerve did not pierce the coracobrachialis muscle proximally. CONCLUSIONS: In clinical situations, nerve defects are usually larger than the gain observed when doing a 6-cm humeral shortening. Moreover, this procedure implies a large dissection, a functional loss of certain muscles, and a risk of humeral nonunion. CLINICAL RELEVANCE: In the absence of extensive nerve dissection, the observed change of length is insufficient in the most brachial plexus disruptions to allow for a direct suture instead of long nerve grafts.

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.

Femoral curvature variability in modern humans using three-dimensional quadric surface fitting.

INTRODUCTION: This study analysed femoral curvature in a population from Belgium in conjunction with other morphological characteristics by the use of three-dimensional (3D) quadric surfaces (QS) modelled from the bone surface. METHODS: 3D models were created from computed tomography data of 75 femoral modern human bones. Anatomical landmarks (ALs) were palpated in specific bony areas of the femur (shaft, condyles, neck and head). QS were then created from the surface vertices which enclose these ALs. The diaphyseal shaft was divided into five QS shapes to analyse curvature in different parts of the shaft. RESULTS: Femoral bending differs in different parts of the diaphyseal shaft. The greatest degree of curvature was found in the distal shaft (mean 4.5° range 0.2°-10°) followed by the proximal (mean 4.4° range 1.5°-10.2°), proximal intermediate (mean 3.7° range 0.9°-7.9°) and distal intermediate (mean 1.8° range 0.2°-5.6°) shaft sections. The proximal and distal angles were significantly more bowed than the intermediate proximal and the intermediate distal angle. There was no significant difference between the proximal and distal angle. No significant correlations were found between morphological characteristics and femoral curvature. An extremely large variability of femoral curvature with several bones displaying very high or low degrees of femoral curvature was also found. CONCLUSION: 3D QS fitting enables the creation of accurate models which can discriminate between different patterns in similar curvatures and demonstrates there is a clear difference between curvature in different parts of the shaft.

Determination of repeatability of kinect sensor.

BACKGROUND: The Kinect™ (Microsoft™, Redmond, WA) sensor, originally developed for gaming purposes, may have interesting possibilities for other fields such as posture and motion assessment. The ability of the Kinect sensor to perform biomechanical measurements has previously been studied and shows promising results. However, interday repeatability of the device is still not known. MATERIALS AND METHODS: This study assessed the intra- and interday repeatability of the Kinect sensor compared with a standard stereophotogrammetric device during posture assessment for measuring segment lengths. Forty subjects took part in the study. Five motionless captures were performed in one session to assess posture. Data were simultaneously recorded with both devices. RESULTS: Similar intraclass correlations coefficient (ICC) values were found for intraday (ICC=0.94 for the Kinect device and 0.98 for the stereophotogrammetric device) and interday (ICC=0.88 and 0.87, respectively) repeatability. CONCLUSIONS: Results of this study suggest that a cost-effective, easy-to-use, and portable single markerless camera offers the same repeatability during posture assessment as an expensive, time-consuming, and nontransportable marker-based device.

The lacertus fibrosus of the biceps brachii muscle: an anatomical study.

PURPOSE: The lacertus fibrosus (LF) is involved in various surgical procedures. However, the anatomy, morphometry, topography and biomechanical involvements of LF are not clear. The purpose of this study was to determine the anatomical and morphometric variations of LF, and to correlate this with anthropometric and morphometric measurements of the upper limb. Furthermore, the presence or absence of a deep layer of LF was verified using forearm cross-sections and dissections. METHODS: This anatomical study was performed by observation of dissections and transverse sections obtained from 50 cadavers. Morphometric analyses [length and width of LF and biceps tendon, stature, length of upper limb, forearm, bi-epicondylar width, forearm perimeter, biceps brachii muscle perimeter (BBm)] were also performed. RESULTS: The results demonstrated that there was no significant correlation between LF morphology and morphometric upper limb measurements. The deep layer of LF was observed in all specimens. CONCLUSION: Results of this paper indicate that the LF presents individual characteristics such as length and width. The deeper layer of LF was observed on all specimens. The possible role of LF in force transmission during flexion, BBm moment arm adjustment and supination reduction is discussed in view of these results.

What is the Safest Sprint Starting Position for American Football Players?

The main objective of this study was to perform a biomechanical analysis of three different sprint start patterns to determine the safest position in term of neck injury and Sport-Related Concussion (SRC). The second objective was to collect data on the learning process effect between football players and non-players. Three different sprint initial positions adopted by football players were studied (i.e., 4-, 3- and 2-point positions). Twenty five young healthy males, including 12 football players, participated to this study. A stereophotogrammetric system (i.e., Vicon) was used to record motion patterns and body segments positions. Various measurements related to head and trunk orientation, and player field-of-view were obtained (e.g., head height, trunk bending, time to reach upright position, head speed (vertical direction) and body speed (horizontal direction)). Learning process was found to have no influence on studied parameters. Head redress is also delayed when adopting a 4-point position leading to a reduce field-of-view during the start and increasing therefore the probability of collision. Concerning the three different positions, the 4-point position seems to be the more dangerous because leading to higher kinetic energy than the 2- and 3-point start positions. This study proposes a first biomechanical approach to understand risk/benefit balance for athletes for those three different start positions. Results suggested that the 4-point position is the most risky for football players. Key pointsMotion analysis and biomechanical analysis of the initial start position of the sprint could be used to increase the safety of the football players.Analysis of kinematic and trajectory of the head and the time to reach the upright position could be used to determine whether or not a player can return to play after concussion.A balance needs to be found between player's safety (2-point start) and speed (4-point start).

[Application of the musculo-skeletal modelling software lhpFusionBox to a paleoanthropological problem: the Spyrou Neandertal moves!]. / Application du logiciel de modélisation musculo-squelettique lhpFusionBox à une problématique paléo-anthropologique - Spyrou le Néandertalien marche !

LhpFusionBox is a program originally designed for biomechanical and clinical studies relating to the musculoskeletal system of anatomically modern humans (AMH). The program has recently been adapted for paleontological purposes and used to reconstruct and biomechanically analyse a fossil hominid. There is no complete Neandertal skeleton in the fossil record. The aim of the study was to reconstruct a complete three-dimensional (3D) model of a Neandertal using the relatively complete Spy II Neandertal and to conduct biomechanical feasibility studies on the knee and hamstring moment arms of the skeleton. Different Neandertal specimens were scaled to the size of Spy II to replace incomplete or missing bones. Biomechanical feasibility studies performed on the knee seem to show that Neandertal and AMHh gait is similar and Neandertals were shown to have larger moment arms in the hamstring muscles, which would have given them a mechanical advantage. The complete Neandertal was printed in 3D and used as the base to create the artistic model of "Spyrou" housed at l'Espace de l'Homme de Spy (EHoS) museum.

[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.

Impact of the mandibular divergence on the position of the inferior alveolar nerve and mylohyoid nerve: a computed tomography study and its relevance to bilateral sagittal split osteotomy.

PURPOSE: Bilateral sagittal split osteotomy (BSSO) is the most common procedure used to treat mandibular deformities. BSSO procedures include the Epker technique and the Dal Pont technique which are the most frequently used. Because of the intramandibular pathway of the inferior alveolar nerve (IAN), neurosensory disturbance of the lower lip and chin is the most common complication of BSSO. This study performed quantitative measurements from computed tomographic (CT) data obtained on dry human mandibles. The main aim of the study was to evaluate if mandibular divergence can predict the position of the IAN and the mylohyoid nerve (MHN) to prevent nerve injury. METHODS: After CT and 3D reconstruction of 65 dry mandibles, 30 measurements were made on 3 planes for each hemi-mandible. This allowed analysis of the IAN and MHN pathways. Three groups of hemi-mandibles were created depending on their divergence, and a statistical analysis was performed. RESULTS: Eight out of the 30 measurements showed a significant difference among the 3 groups. There was no significant difference for the remaining 22 measurements. CONCLUSIONS: The IAN seems to have a more superior position in the groups of mandibular hypo- and hyper-divergence. Orthognathic surgeons should use a more superficial retromolar bone incision in these cases. Finally, the Epker technique would be safer for preserving the MHN in normo- and hypo-divergent patients.

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.

Radiocapitellar joint contacts after bipolar radial head arthroplasty.

PURPOSE: The purpose of this study was to determine radiocapitellar contacts before and after radial head replacement, using the bipolar design of Judet. METHODS: Joint contacts were measured by moulding the joint surfaces of 6 fresh-frozen cadaveric specimens, in various positions of elbow flexion and forearm rotation. RESULTS: Expressed as function of the radial cup, contact areas averaged 44% in the normal elbow, decreasing with flexion and increasing with supination (P < .05). After prosthetic implantation, contact areas averaged 33% and remained quite similar, irrespective of elbow position. Subluxation of the prosthetic head over the lateral margin of the trochlea was seen systematically with supination. CONCLUSIONS: Because of intraprosthetic mobility, contact areas were not dependant on elbow position. This adaptability, however, also led to abnormal positioning of the prosthetic radial head with supination, subluxing over the trochlea lateral margin.

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.

Inefficacy of the cementation of femoral head collapse in glucocorticoid-induced osteonecrosis.

The objective of this paper was to assess the efficacy of cementation of the femoral head in stage III glucocorticoid-induced osteonecrosis. Ten hips (nine patients) were treated by the injection of low-viscosity cement to reduce the collapse. The follow up included clinical and radiological assessments preoperatively and at 3, 6 and 12 months after surgery. The visual analogue scale (VAS) score, the Lequesne index and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score did not show any significant improvement. Eight of the ten hips showed a worsening of the collapse and required total hip arthroplasty during follow up. The mean time before total hip replacement was 8.6 +/- 7 months. The other two hips did not show any relapse of collapse nor functional worsening at the maximum follow up of 5 years. Our results suggest that cement injection is not a treatment that should be proposed for glucocorticoid-induced osteonecrosis.

Expression of Msx1 and Dlx1 during Dumbo rat head development: Correlation with morphological features.

The Dumbo rat possesses some characteristics that evoke several human syndromes, such as Treacher-Collins: shortness of the maxillary, zygomatic and mandibular bones, and low position of the ears. Knowing that many homeobox genes are candidates in craniofacial development, we investigated the involvement of the Msx1 and Dlx1 genes in the Dumbo phenotype with the aim of understanding their possible role in abnormal craniofacial morphogenesis and examining the possibility of using Dumbo rat as an experimental model for understanding abnormal craniofacial development. We studied the expression of these genes during craniofacial morphogenesis by RT-PCR method. We used Dumbo embryos at E12 and E14 and included the Wistar strain as a control. Semi-quantitative PCR analysis demonstrated that Msx1 and Dlx1 are expressed differently between Dumbo and Wistar rats, indicating that their low expression may underly the Dumbo phenotype.

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.