Quantitative study of knee joint surface configurations using a morpho-functional approach

Several models exist in the literature to describe knee kinematics. In this paper we propose a morpho-functional approach based on the determination of a simulated kinematics of flexion/extension from a unique CT scan acquisition. We will compare this kinematics to the real one obtained from experiments on one cadaver. In parallel, we have developed quantitative tools for the assessment of the motion. As the computation of these tools depends on the bone morphology, they can describe the state of the joint, which is not classical in the literature. Both tools follow the evolution of the distances between two bones during motion. They are called the Figure of Articular Coherence and the Index of Articular Coherence. In order to verify the relevance of these tools, we have tested them to compare different surgeries of Anterior Cruciate Ligament (ACL) reconstruction.

Shoulder motion analysis using simultaneous skin shape registration

A new non-invasive approach is proposed to study joint motions. It is based on dynamic tracking of the skin shape. A robust simultaneous registration algorithm (Iterative Median Closest Point) is used to follow the evolving shape and compute the rigid motion of the underlying bone structures. This new method relies on the differentiation of the rigid and elastic parts of the shape motion. A skin marker network is tracked by a set of infrared cameras. Unlike usual techniques, the algorithm tracks the instantaneous polyhedral shape embedding this network. This innovating approach is expected to minimize bias effect of skin sweeps and give some new information about the underlying soft tissue activities. Current application addresses the motion of the shoulder complex (humerus, clavicle and scapula). It is compared with two marker-based methods published in the literature. Preliminary results show significant differences between these three approaches. The new approach measurements give rise to greater rotations.

[Satisfaction with technological equipment in individuals with tetraplegia following spinal cord injury]

OBJECTIVE

To measure the acquisition, use and satisfaction with high technology equipment by spinal cord injured tetraplegic subjects.

DESIGN AND SETTING

A questionnaire was mailed to 102 tetraplegic subjects who were hospitalised in the rehabilitation center of Kerpape (Ploemeur, France) between 1998 and 2004, and 59 subjects responded. The questionnaire asked about the use of telephones, computers, wheelchairs and environmental controls at home.

RESULTS

When a piece of equipment was acquired, it was very often used. Patient satisfaction with equipment was 79.3%. Home phones and mobile phones were often used with options such as hands-free devices (78 and 59% respectively). A total of 64.4% of subjects acquired a manual wheelchair and 61% a power wheelchair. The most commonly acquired options on the power wheelchairs were the powered recline (73,7%) and tilt (71,1%) systems. All options were used but all were more desired than acquired. A total of 27.1% of subjects desired a pushrim-activated power-assist wheelchair, but only 15.3% had acquired one; 695% of subjects had a computer. Communication was the first use for the computer (82.5%); 49.2% of subjects had acquired an environmental control system, but 20% desired one. The first reason for lack of acquisition was financial difficulties but also accessibility and information problems. The factor that influenced the acquisition and need for equipment was the degree of spinal cord injury. No other factor reduced patient satisfaction with equipment.

CONCLUSION

Patients were satisfied with the equipment they acquired. But their needs, especially wheelchair options and environmental control systems, were not satisfied.

Kinematic analysis of handbike propulsion in various gear ratios: implications for joint pain

BACKGROUND

Though considered more efficient and less constraining than the hand-rim wheelchair, the handbike has rarely been studied especially as regards its kinematic parameters. The hypothesis of this investigation is that the range of upper extremity motions are risk factors for joint pain during handbiking as is the case during hand-rim wheelchair propulsion. This paper aims to study handbike propulsion in maximal sprint conditions in order to determine potential risk factors for joint pain.

METHODS

Eight able-bodied participants with no experience in handbike propulsion performed three sprints of 8 s each using three gear ratios in a handbike mounted on a home-trainer. The mean velocity per arm cycle, the cycle frequency, the angular parameters for the upper extremities were calculated, as well as the corresponding angular accelerations, with the help of a 3D movement analysis.

FINDINGS

An increase in gear ratio (22/21, 32/21, and 44/21) significantly increases the maximal velocity, the flexion/extension of the trunk, as well as the adduction/abduction of the elbow, while it reduces the frequency of movements and the flexion/extension angular accelerations of the shoulder and the elbow. Regardless of what gear ratio is used, maximal angular amplitudes of the upper extremities are comparable to the values obtained with a hand-rim wheelchair. Interpretation. The high amplitudes and fast angular joint accelerations of the upper extremity found in this study are near or superior to the ergonomic recommendations generally advised. These considerations could be taken into account to prevent overuse injuries.

[Intrathecal therapy for bladder hyperreflexia]

Intrathecal clonidine was tested for the control of bladder hyperreflexia resistant to pararsympathicolytic drugs in spinal cord injured patients. Urodynamic parameters were significantly improved after acute bolus of intrathecal low doses of clonidine. Unfortunately, the chronic intrathecal infusion of clonidine induced cardiovascular side-effects. Intrathecal baclofen did not modified significantly neurogenic bladder dysfunction from spinal lesion. But intrathecal baclofen modified penile erection quality and impaired the ejaculation reflex induced by penile vibratory stimulation in the same population.

[Spastic gait analysis. Contribution of the motion lab]

Etienne-Jules Marey introduced gait motion analysis at the end of the XIXth century. It was rapidly adopted by clinicians and Charcot used it at the beginning of the XXth century in La Salpêtrière. Motion analysis was widely used after the first optoelectronic system was built by Furné in 1968. The optoelectronic system calculates the orientation of each body segment in the space after the determination of the space co-ordinates of cutaneous markers placed over them. It is particularly useful for spastic gait. Many disturbances of kinematics and kinetics have been described during spastic gait. They are the consequences of spasticity and other motor and sensory deficits of central nervous system lesions. Motion analysis must be coupled with electromyographic recording of spastic muscles activity which, with kinetic analysis, enables distinguishing the mechanisms underlying gait disturbances. Motion analysis provides clinicians with an indispensable tool for understanding spasticity and evaluating therapeutic efficacy.

Effect of intrathecal clonidine on group I and group II oligosynaptic excitation in paraplegics

We investigated the possibility that a change in transmission in group II pathways contributes to the spasticity of patients with spinal lesions. Thirteen patients were tested by measuring the quadriceps stretch reflex (Ashworth scale), the threshold of the quadriceps H reflex, and the oligosynaptic facilitation of the quadriceps H reflex elicited by volleys to groups I and II afferents in the common peroneal nerve (CPN). All these tests were performed before and after intrathecal injection of clonidine (60 microg). Early group I CPN-induced excitations occurred in 13 patients, and late group II CPN-induced excitations in 12. Both facilitations were, on average, significantly greater than those reported for normal subjects, but these increases were not correlated with the clinically assessed spasticity. Clonidine caused a constant, prolonged and dramatic decrease in spasticity, but did not alter the threshold of the quadriceps H reflex. CPN-induced group I and group II non-monosynaptic excitations of quadriceps motoneurones were significantly decreased, although they did not return to normal values. These results provide a further indication that group II pathways gives rise to the heteronymous late CPN-induced excitation. The pathophysiological role of a change in transmission in group II pathways in spasticity is discussed.

Intrathecal clonidine for controlling spastic hypertonia

Intrathecal clonidine is a powerful antispastic drug. Its mechanism of action is more selective than baclofen. The acute effects are reviewed. An assessment of side effects of clonidine during chronic infusion is needed.

Effects of intrathecal clonidine injection on spinal reflexes and human locomotion in incomplete paraplegic subjects

We studied the effect of the intrathecal (i.t.) injection of clonidine (30, 60 and 90 microg) on the polysynaptic spinal reflexes (PSR) elicited by electrical stimulation of flexor reflex afferents (FRA), monosynaptic reflex and gait of 11 subjects with spinal cord injuries. The effect of clonidine administration on gait velocity, stride amplitude and duration was measured in eight subjects who were able to walk. Five subjects were able to walk after intrathecal injection of clonidine and three were not able to stand up. Three subjects improved their gait velocity after clonidine administration; one (S6) increased his stride amplitude; the two others decreased their cycle durations. The tibialis anterior seemed to be more regularly activated during gait. Spasticity was reduced dramatically (P<0.0001) after i.t. clonidine injection, but there was no statistically significant difference in the soleus H reflex (no effect on Hmax/Mmax). Clonidine administration decreased the amplitude of the early PSR (90-120 ms, N=4) and the threshold and maximal integrated EMG corresponding to the late response (140-450 ms, N=7). This effect was dose dependent (30, 60 and 90 microg). Placebo injection (N=4) caused no change. The changes in spinal reflexes, with a large reduction in spasticity, no change in motoneurone excitability and a large decrease in PSR, suggest that clonidine acts at a premotoneuronal level, possibly by presynaptic inhibition of group II fibres. The increase in gait velocity in three subjects could have been due to reduced spasticity or activation of spinal circuitry.