Geometry-based algorithm for the prediction of nonpathologic mandibular movement.

PURPOSE: The goal of this study was to create a model for human mandibular movement prediction based on the geometry of the mandible. MATERIALS AND METHODS: Ten nonpathologic individuals underwent motion tracking and sagittal radiographs. From the data, a mathematical algorithm for mandibular movement prediction was developed based on mandibular geometry. The algorithm was then used to predict the mandibular movement of a cadaver subject. The algorithm was also validated in a living subject by comparing to recorded mandibular movement. RESULTS: Both mandibular movement predictions were free of bone collisions and showed mandibular movement that mimicked the in vivo situation. Comparisons between the predicted and recorded mandibular movements for the living human subject verified that the prediction model was accurate. CONCLUSIONS: The mandibular movement can be predicted based on the mandibular opening radius. The model is validated in living human subjects and shows effectiveness in predictions for cadaver models. Mandibular movement prediction may be a useful tool for physicians as well as investigators who focus on temporomandibular joint research.     

Refined myoelectric control in below-elbow amputees using artificial neural networks and a data glove

PURPOSE: To develop a system for refined motor control of artificial hands based on multiple electromyographic (EMG) recordings, allowing multiple patterns of hand movements. METHODS: Five subjects with traumatic below-elbow amputations and 1 subject with a congenital below- elbow failure of formation performed 10 imaginary movements with their phantom hand while surface electrodes recorded the EMG data. In a training phase a data glove with 18 degrees of freedom was used for positional recording of movements in the contralateral healthy hand. These movements were performed at the same time as the imaginary movements in the phantom hand. An artificial neural network (ANN) then could be trained to associate the specific EMG patterns recorded from the amputation stump with the analogous specific hand movements synchronously performed in the healthy hand. The ability of the ANN to predict the 10 imaginary movements offline, when they were reflected in a virtual computer hand, was assessed and calculated. RESULTS: After the ANN was trained the subjects were able to perform and control 10 hand movements in the virtual computer hand. The subjects showed a median performance of 5 types of movement with a high correlation with the movement pattern of the data glove. The subjects seemed to relearn to execute motor commands rapidly that had been learned before the accident, independent of how old the injury was. The subject with congenital below-elbow failure of formation was able to perform and control several hand movements in the computer hand that cannot be performed in a myoelectric prosthesis (eg, opposition of the thumb). CONCLUSIONS: With the combined use of an ANN and a data glove, acting in concert in a training phase, amputees rapidly can learn to execute several imaginary movements in a virtual computerized hand, this opens promising possibilities for motor control of future hand prostheses.     

Kinematic analysis of tongue movements in dysarthria following traumatic brain injury using electromagnetic articulography

Electromagnetic articulography (EMA), a technique that uses alternating magnetic fields to track the movement of miniature receiver coils affixed to the articulators, was used to assess the speed and accuracy of tongue movements exhibited by an individual with dysarthria following severe traumatic brain injury (TBI). Three receiver coils were attached to the TBI subject's tongue and the movements of these coils were recorded during five productions of three single syllable real words consisting of the lingual consonants /t, s, k/ in the word-initial position. A non-neurologically impaired adult male served as a control subject. A range of kinematic parameters was analysed from the consonant productions including the movement trajectories, velocity, acceleration, distance, and duration of tongue movements. Examination of the complex interactions between the kinematic parameters recorded for the TBI subject revealed a disturbance in the 'control' of tongue speed rather than a disturbance in speed per se , as it was found that the TBI subject exhibited difficulty in decelerating his tongue movements appropriately on the approach up to the palate during consonant production. The difficulty noted in deceleration resulted in inaccurate tongue movements that overshot the point of intent (in the case of /t/) and may have been instrumental in reducing the length of time that the tongue remained at the palate (in the case of /s/ and /k/) in comparison to the control subject. The disturbances identified in the kinematic parameters recorded provided objective insights into the nature of the articulatory disturbances responsible for the deviant speech feature, consonant imprecision, perceived in the TBI subject's speech. The study stresses the importance of examining a range of kinematic parameters and the interactions between these parameters in attempting to determine the nature of articulatory disturbances exhibited by individuals with dysarthria following TBI.     

Distortion of chest movement by increased airways resistance

The movement of the chest during breathing has been recorded in normal and asthmatic subjects by means of electronic transducers which measured changes in anteroposterior and lateral diameters. Preliminary studies showed that exercise-induced bronchoconstriction caused distortion of the movement of the diameters in relation to each other and to volume change recorded at the mouth. Because of the thoracic gas compression which occurs during breathing, volume change at the mouth does not represent the change in chest volume and further studies were therefore undertaken in a whole-body plethysmograph. These studies showed that the addition of a resistance to the airway of a normal subject distorted the movement of one diameter (usually the anteroposterior) in relation to the other and to volume. With exercise-induced asthma, the movement of both diameters was affected with the anteroposterior lagging behind the volume change. There was an approximate linear relationship between the degree of distortion and airways resistance in the asthmatic subjects and in one normal subject. The physical sign of costal margin paradox could be related to the severity of the obstruction.     

Continuous monitoring of gastric movements in rats subjected to restraint

Gastric motility was recorded continuously by strain gage technique in two groups of animals, subjected to 24 hours' restraint. Ten rats served as control and 10 were pretreated with 100 mg/kg of cimetidine. The electric signals, produced by gastric movements, were recorded by a tape recorder and were then further analysed by a computer. In order to make comparison between the two groups of animals a precise quantitative analysis of gastric movements was performed by using different computer programs. Three parameters of recordings (frequency, size of contractions and area under the waves) have been used to characterize the curves. It was established that there was no essential difference in the two experimental groups concerning the gastric motility pattern. Brisk gastric movements could be recorded during the whole period of restraint. It may be concluded that increased gastric movements may not play an important role in the pathogenesis of stress-induced mucosal lesions and that cimetidine exerts its anti-ulcer effect via other mechanisms than influencing gastric motility.     

Multifidus spasms elicited by prolonged lumbar flexion

STUDY DESIGN: The electromyogram of the L1-L7 multifidus muscles of the in vivo cat were recorded while applying a prolonged steady displacement to the lumbar spine through the L4-L5 supraspinous ligament, simulating a moderate anterior flexion. OBJECTIVE: To demonstrate that tension-relaxation and laxity of the viscoelastic structures (ligaments, discs, and capsules) induced by prolonged static flexion of the spine results in loss of reflexive muscular stabilizing activity and in muscular disorders that may lead to or are associated with low back pain. SUMMARY OF BACKGROUND: Epidemiologic data show that prolonged loading of the spine, such as in some occupational activities, can cause low back pain and muscle spasms. Direct experimental evidence linking prolonged loading to a decrease in spinal stability, low back pain, and muscle spasms was not found. It was hypothesized, however, that mechanoreceptors in the viscoelastic structures, when strained, reflexively activate the multifidus muscles to maintain intervertebral stability; that the reflexive muscular activity decreases with stress-relaxation and laxity in the viscoelastic structures; and that when severe strain and possible damage of the viscoelastic structures occurs with time, nociceptive receptors elicit spasms in the musculature and possible pain. METHODS: The lumbar spine of seven in vivo cat preparations was displaced through the L4-L5 supraspinous ligament into moderate flexion that was steadily maintained for 50 minutes while intramuscular electromyograms were recorded from each of the multifidus muscles of L1-L2 through L6-L7. Load and electromyogram were continuously monitored and recorded. Five additional preparations were used as controls, in which dissection and recordings were identical, but the lumbar flexion was excluded. RESULTS: Prolonged flexion of the lumbar spine resulted in initial reflexive electromyogram from the multifidus muscles that decreased to approximately 5% of its initial value as tension-relaxation began in the viscoelastic structures within the first 3 minutes, after which, random and unpredictable electromyogram discharges (i.e., spasms) of high amplitude were recorded from different levels. In some preparations the spasms were present in L1-L4, and in others in all the levels. In other preparations the spasms were recorded only at L5 and L6. The onset of the spasms was also unpredictable, because they were initiated in some cases within 2-3 minutes after the spine was loaded. In other cases, the spasms were observed anytime during the test period and up to 20 minutes after the load was removed. Spasms were also observed in the spinalis and longissimus muscles. CONCLUSIONS: Prolonged flexion of the lumbar spine results in tension-relaxation and laxity of its viscoelastic structures, loss of reflexive muscular activity within 3 minutes and electromyogram spasms in the multifidus and other posterior muscles.     

Semiquantitative assessment of hindlimb movement recovery without intervention in adult paraplegic mice

STUDY DESIGN: Experimental laboratory investigation of hindlimb movement recovery in chronic paraplegic mice. OBJECTIVES: Development of an assessment method to discriminatively quantify motor and locomotor-like movements of paraplegic mice. SETTING: Laval University Medical Center, Quebec, Canada. METHODS: Signs of 'functional recovery' were examined in open-field condition during 1 month in adult mice with a complete spinal cord transection at the low-thoracic level. RESULTS: None of the mice exhibited hindlimb movements after spinalization. At 7 days, 33% of them displayed weak nonbilaterally alternating movements (NBA). At 14 days, increased NBA were observed and the first bilaterally alternating movements (BA) in 10% of the mice. A progressive increase of movement frequency and amplitude was found after 2-3 weeks. By the end of the month, 86% displayed mixed NBA and BA. However, none of them recovered the ability to stand or bear their own weight with the hindlimbs. CONCLUSION: This study reports signs of partial hindlimb movement recovery in chronic paraplegic mice and provides evidence of plasticity in sublesional circuits of neurons occurring in the absence of inputs from the brain, locomotor training or pharmacological treatment. This assessment method can be used to characterize hindlimb movements in complete spinal cord transected mice tested in open-field condition.     

Trunk posture monitoring with inertial sensors

Measurement of human posture and movement is an important area of research in the bioengineering and rehabilitation fields. Various attempts have been initiated for different clinical application goals, such as diagnosis of pathological posture and movements, assessment of pre- and post-treatment efficacy and comparison of different treatment protocols. Image-based methods for measurements of human posture and movements have been developed, such as the radiography, photogrammetry, optoelectric technique and video analysis. However, it is found that these methods are complicated to set up, time-consuming to operate and could only be applied in laboratory environments. This study introduced a method of using a posture monitoring system in estimating the spinal curvature changes during trunk movements on the sagittal and coronal planes and providing trunk posture monitoring during daily activities. The system consisted of three sensor modules, each with one tri-axial accelerometer and three uni-axial gyroscopes orthogonally aligned, and a digital data acquisition and feedback system. The accuracy of this system was tested with a motion analysis system (Vicon 370) in calibration with experimental setup and in trunk posture measurement with nine human subjects, and the performance of the posture monitoring system during daily activities with two human subjects was reported. The averaged root mean squared differences between the measurements of the system and motion analysis system were found to be <1.5° in dynamic calibration, and <3.1° for the sagittal plane and ≤2.1° for the coronal plane in estimation of the trunk posture change during trunk movements. The measurements of the system and the motion analysis system was highly correlated (>0.999 for dynamic calibration and >0.829 for estimation of spinal curvature change in domain planes of movement during flexion and lateral bending). With the sensing modules located on the upper trunk, mid-trunk and the pelvic levels, the inclination of trunk segment and the change of spinal curvature in trunk movements could be estimated. The posture information of five subjects was recorded at 30 s intervals during daily activity over a period of 3 days and 2 h a day. The preliminary results demonstrated that the subjects could improve their posture when feedback signals were provided. The posture monitoring system could be used for the purpose of posture monitoring during daily activity.     

Paroxysmal Dyskinesia

Opinion statement This group of disorders is characterized by periodic sudden events of involuntary movement. The clinical range of these involuntary movements is wide including tonic spasms, choreiform and athetoid movements and sustained dystonic postures. Confusion with reflex forms of epilepsy has been common in the past, but in general, paroxysmal dyskinesias are not associated with alterations in consciousness or epileptiform activity on electroencephalogram. The underlying basis of the paroxysmal dyskinesia is under active investigation as is their relationship to epilepsy and other paroxysmal disorders [1,2, Class III; 3].     

Bewegungen der Kiefergelenke während der endotrachealen Intubation

Laryngoscopy causes temporary postoperative dysfunction of the temporomandibular joint (TMJ): during iatrogenic TMJ manipulation in anaesthetised patients, the TMJs have lost the protection afforded by the tone of the surrounding muscles. Thus far, the exact type and extent of TMJ movements have not been known. The purpose of this study was to develop a method to visualise and assess TMJ movements during intubation by means of electronic axiography, a diagnostic monitor of TMJ movements used in dentistry: registration of the hinge axis (HA) as an equivalent of the condylar paths on extra-oral sagittally mounted, parallel plates. The HA is individually defined in each patient by the pure, rotating TMJ movement during initial mouth opening (no farward gliding of the condyles, incisor distance up to 10?mm). The parallel plates are placed in the TMJ region in the skull-mounted plate bow; both registration tips (?drawing“ the HA tracings on the electronic plates) are connected to the mandible by a face bow, paraocclusally fixed to the teeth. The face bow is individually shaped for each patient to allow mask ventilation and free movement of the laryngoscope during intubation. HA tracings are registered and calculated for both sides independently every 24?ms with the SAM/Klett system and presented on sagittal and frontal projections. In the operating theatre, the active mouth-opening traces (MOT) are registered first and the passive endotracheal intubation traces (EIT) after induction of anaesthesia (same head position). With informed consent and approval by the ethics committee of the Landesärztekammer Rheinland-Pfalz, 40 male patients (ASA I, Mallampati I, limb surgery) were randomly allocated to four groups (n=10 each). OS: Oral intubation, suxamethonium (1.5?mg/kg); OV: Oral intubation, vecuronium (0.1?mg/kg); NS: Nasal intubation, suxamethonium (1.5?mg/kg); and NV: Nasal intubation, vecuronium (0.1?mg/kg). Intubation was performed 100?s after injection of the relaxant. Pre- and postoperatively (every 24?h over 3 days, in case of positive findings longer) recorded were: active movements of the mandible (maximal mouth opening/max. laterotrusion); dysfunction of the TMJ; and pain sensation in the TMJ (Helkimo rating). MOTs and EITs were recorded and analysed with the system described and typical EIT patterns were identified: bland, clinically uneventful intubations (n=7), massive distraction and laterotrusion of the EIT compared to the MOT (n=24), and blocked or limited TMJ movements resulting in intubation problems (n=1). With the method presented, TMJ movements could be visualised during endotracheal intubation for the first time. It can be used to assess techniques, routes, and instruments for intubation as well as to evaluate potential traumatising movements during endotracheal intubation.     

Dorsolateral prefrontal cortex prevents short-latency saccade and vergence: a TMS study

This study explores whether vergence eye movements along the median plane can be triggered with short latencies, and the role of the dorsolateral prefrontal cortex (DLPFC) in controlling such movements. We used a gap paradigm and applied transcranial magnetic stimulation (TMS) in 10 humans making saccades or vergence. TMS over the motor cortex had no effect on any eye movement parameter. TMS over DLPFC influenced eye movement initiation but not their metrics. TMS over the right DLPFC accelerated the triggering of saccades bilaterally but did not influence divergence. TMS over the left DLPFC speeded up the triggering of ipsilateral saccades and exacerbated the anticipatory mode of triggering of divergence. For convergence, TMS effects were mild: rightward TMS increased the proportion of short latencies but failed to shorten the group mean latency; leftward TMS influenced triggering in some individuals only. For saccades and convergence under TMS, some subjects showed an emerging population of short latencies in their latency distribution. Horizontal saccadic intrusions (80% of trials) and vertical saccades (recorded in one subject) intruding on vergence were unlikely to assist vergence triggering. We conclude that the prefrontal mechanisms underlying voluntary eye movement control are similar for saccades and vergence although some specificities exist.     

Long-term intrathecal baclofen infusion for treatment of spasticity

Seven patients with spasticity of spinal cord origin have been maintained for up to 2 years with continuous spinal intrathecal infusion of baclofen. Prior to treatment, all of the patients had severe rigidity in their lower limbs and most had frequent and extensive spontaneous spasms, all of which greatly interfered with their activities of daily living. Oral antispasmodic medications were ineffective or caused central side effects. The patients underwent implantation of a programmable drug pump connected to a lumbar subarachnoid catheter. Within days of beginning continuous intrathecal baclofen infusion, the muscle tone was reduced to normal levels and spasms were eliminated. Over the ensuing months, muscle tone remained normal, but short-duration spasms could be induced by some activities. The greatest benefits to the patients were improvement in activities of daily living and better sleep due to reduced spasms. The baclofen doses were increased over the first few months but then were stabilized or only increased slightly, with the maximum dose being 650 micrograms/day. The most serious complications were two drug overdoses which took several days to clear up and were due to malfunctions of an earlier pump model. Baclofen clearance from the cerebrospinal fluid occurs with a half-life of 5 hours. The most serious concern in maintaining patients indefinitely on intrathecal baclofen is whether drug tolerance will eventually occur.     

Homotypic cell-cell contacts stimulate the motile activity of rat prostate cancer cells

OBJECTIVE: To characterize the effect of homotypic cell-to-cell collisions upon the motile activities of two rat prostatic cancer cell lines of markedly different metastatic potential. MATERIALS AND METHODS: The movements of strongly and weakly metastatic MAT-LyLu and AT-2 cells, respectively, were recorded under an inverted microscope at 37 degrees C. The motile activities of the cells at various cell densities were characterized quantitatively by computer-aided tracking methods and image analysis. The following variables were assessed: speed of movement, final displacement, coefficient of movement efficiency, diffusion constant and positive flow. RESULTS: MAT-LyLu and AT-2 cells showed only limited motile activity in sparse cultures where there was little contact amongst the cells. However, under these and all other subsequent conditions tested, the motile activity of the MAT-LyLu cells was higher than the AT-2 cells. As the density of the cultured cells was increased (leading to more cell-to-cell contacts) there was a significant increase in motility. This effect was more pronounced for the AT-2 than for the MAT-LyLu cells, resulting in visible acceleration of movement by direct physical contact among the colliding cells. The motile activities of the tumour cells was only slightly affected by conditioned media. CONCLUSION: Homotypic collisions between migrating prostatic cancer cells can strongly stimulate their motility. The effect of increased contact is greater on the weakly metastatic cells, such that at high cell density, the difference in the motilities of weak and strong metastatic cells is greatly reduced.     

猴腭咽闭合运动模式实验模型的建立

目的：本文鉴于目前缺乏腭咽闭合运动模式的动物模型,利用和人类腭咽结构相似的成年雄性猕猴建立人工电刺激诱导软腭肌肉发生腭咽闭合运动模式的实验模型,为临床优化治疗相关疾病提供依据。方法：对活体成年猕猴软腭部位肌肉的进行手术解剖,准确定位腭帆提肌、腭帆张肌、咽腭肌、舌腭肌,埋植针式电极进行有效刺激,利用鼻咽纤维镜观察软腭肌肉的运动情况。结果：利用针电极刺激猕猴软腭肌肉能诱发有效的肌肉收缩,达到腭咽闭合状态,确定了有效的刺激参数。在刺激电压为3V时,软腭发生收缩;刺激电压为5V时,发生腭咽闭合。结论：针式电极刺激猕猴软腭肌肉能够发生有效收缩,利用猕猴建立的腭咽闭合动物模型可靠。     

Watching your foot move--an fMRI study of visuomotor interactions during foot movement

The objective of this study was to investigate brain areas involved in distinguishing sensory events caused by self-generated movements from similar sensory events caused by externally generated movements using functional magnetic resonance imaging. Subjects performed 4 types of movements: 1) self-generated voluntary movement with visual feedback, 2) externally generated movement with visual feedback, 3) self-generated voluntary movement without visual feedback, and 4) externally generated movement without visual feedback, this design. This factorial design makes it possible to study which brain areas are activated during self-generated ankle movements guided by visual feedback as compared with externally generated movements under similar visual and proprioceptive conditions. We found a distinct network, comprising the posterior parietal cortex and lateral cerebellar hemispheres, which showed increased activation during visually guided self-generated ankle movements. Furthermore, we found differential activation in the cerebellum depending on the different main effects, that is, whether movements were self- or externally generated regardless of visual feedback, presence or absence of visual feedback, and activation related to proprioceptive input.     

A radiostereometric analysis of the movements of the sacroiliac joints in the reciprocal straddle position

STUDY DESIGN: A Radiostereometric analysis of the reciprocal straddle position. OBJECTIVES: To evaluate the magnitude of rotation in the sacroiliac joints in the reciprocal straddle position. SUMMARY OF BACKGROUND DATA: The reciprocal straddle position has been objectified in different studies, using different techniques, to show a sacroiliac motion between 5 degrees and 36 degrees. Previous studies with radiostereometric analysis during different provocations reported much smaller movements. METHODS: Six women with posterior pelvic pain of long duration after pregnancy (n = 5) and sacroiliitis (n = 1) underwent radiostereometric analysis in the sustained reciprocal straddle position. RESULTS: A reciprocal movement could be demonstrated in the sacroiliac joints in the reciprocal straddle position. However, the movements were 10 times smaller than reported in earlier studies of the reciprocal straddle position. CONCLUSIONS: It was possible to demonstrate reciprocal movements of the sacroiliac joints in the straddle position. However, the radiostereometric analysis technique showed the movements to be small, as reported in other mobility studies.     

A biomechanical study to compare spinal movement in a healthy volunteer during extrication between ‘chain cabling’ and ‘roof off’ methods of extrication

IntroductionFollowing a motor vehicle collision some patients will remain trapped. Traditional extrication methods are time consuming and focus on movement minimisation and mitigation. ‘Chain cabling’ is an alternative method of extrication used in some countries. The optimal extrication strategy and the effect of extrication methods on spinal movement is unknown. This study compares ‘chain cabling’ to the established roof removal method of extrication on spinal movement.MethodsBiomechanical data were collected using Inertial Measurement Units on a single healthy volunteer during multiple experiments. The extrication types examined were chain cabling and roof removal. Measurements were recorded at the cervical and lumbar spine, and in the anteroposterior (AP) and lateral (LR) planes. Total movement (travel), maximal movement, mean, standard deviation and confidence intervals are reported.ResultsEight experiments were performed using each technique. The smallest mean overall movements were recorded during roof-off extrication (cervical spine 0.6 mm for AP and LR, lumbar spine 3.9 mm AP and 0.3 mm LR).The largest overall mean movements were seen with chain cabling extrication (cervical spine AP 5.3 mm. LR 6.1 mm and lumbar spine 6.8 mm AP and 6.3 mm LR).ConclusionIn this study of a healthy volunteer, roof-off extrication was associated with less movement than chain cabling. The movement associated with chain cabling extrication was similar to that previously collected for other extrication types.     

Functional Model of Monofin Swimming Technique Based on the Construction of Neural Networks

In this study we employed an Artificial Neuronal Network to analyze the forces flexing the monofin in reaction to water resistance. In addition we selected and characterized key kinematic parameters of leg and monofin movements that define how to use a monofin efficiently and economically to achieve maximum swimming speed. By collecting the data recorded by strain gauges placed throughout the monofin, we were able to demonstrate the distribution of forces flexing the monofin in a single movement cycle. Kinematic and dynamic data were synchronized and used as entry variable to build up a Multi-Layer Perception Network. The horizontal velocity of the swimmer’s center of body mass was used as an output variable. The network response graphs indicated the criteria for achieving maximum swimming speed. Our results pointed out the need to intensify the angular velocity of thigh extension and dorsal flexion of the feet, to strengthen velocity of attack of the tail and to accelerate the attack of the distal part of the fin. The other two parameters which should be taken into account are dynamics of tail flexion change in downbeat and dynamics of the change in angle of attack in upbeat.

Key points

• The one-dimensional structure of the monofin swimming creates favorable conditions to study the swimming technique.
• Monofin swimming modeling allows unequivocal interpretation of the propulsion structure. This further permits to define the mechanisms, which determine efficient propulsion.
• This study is the very first one in which the Neuronal Networks was applied to construct a functional/applicable to practice model of monofin swimming.
• The objective suggestions lead to formulating the criteria of monofin swimming technique, which plays the crucial role in achieving maximal swimming speed.
• Theoretical and empirical (realistic) verification created by parameters indicate by neural networks, paves the way for creating suitable models, which could be employed for other sports.

Key words: Kinematics, dynamics, leg and fin movements, modeling     

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.     

Interfragmentary motion in tibial osteotomies stabilized with ring fixators

Relative movement of bone fragments affects healing processes. In vivo data exist for patients with reduced transverse fractures only. The gap movements that occur under more complex conditions such as in tibial osteotomies, however, are unknown. The goal of this study was to determine the initial gap movements in tibial correction osteotomies, to monitor movements during the early healing period, and to determine the suitability of initial fixation stability in relation to daily activities. The interfragmentary movements were measured in six patients with correction osteotomies stabilized by Ilizarov ring fixator constructs until union or until conversion to internal fixation. Consolidation was determined by clinical evaluation and standard radiographic techniques. Co-contraction led to gap movements comparable with level walking or standing. Shear generally exceeded axial compression. Although ground reactions and fixation stiffness were comparable with those reported for reduced fractures, movement magnitudes generally were larger than 2 mm. The shear movement component reflected the nature of the mechanical conditions at the bone gap. In a direct comparison with data from animal experiments, the local mechanical environment at the bone gap seemed unstable rather than overly stable. The method introduced in this study opens the perspective of adjusting osteosynthesis stability to the specific needs of each patient.