Computer added locomotion by implanted electrical stimulation in paraplegic patients (SUAW).

Paraplegia means a live long sentence of sensory loss, paralysis and dependence with approximately 1000 new victims in every European country every year and 11.500 new traumatic SCI cases in the US. respectively. Sixty percent are injured before age 30. More than 90% of SCI victims may survive with nearly normal experience of live. Most patients will recover somewhat from SCI over time but no patient who remained plegic for one year regains voluntary motor function after that time period. Despite remarkable efforts and recent achievements in rehabilitation no treatment can be recommended so far to enhance functional recovery and restoring locomotion in paraplegic humans. FES as a technical compensation has become therefore a challenging treatment to restore muscle function and to prevent atrophy and to improve mobility and quality of life at the same time. In paraplegics FES could be the basis to restore locomotion. One of the advantages of an implanted FES version (neuroprosthesis) is that the FES system, electrodes, and cables remain permanently implanted within the body, so that the patient can stay without cables, the programmer attached to the crutches. The SUAW project, supported under BIOMED II Programme by the European Community was aimed to finalize and to put into practice the results of previous research and development. The novel implant with an ASCI-Chip has 16 channels, 8 on each side, 20 mA for monopolar and 2 mA for bipolar stimulation, only one electrode can be stimulated at a given time. Stimulation of 6 muscle groups of both legs are known to be sufficient for locomotion: M. ileopsoas (erector of the body, hip flexor), M. gluteus maximus (hip extensor), M. gluteus medius (lateral hip stabilisator, knee abductor), Mm. hamstrings (knee flexor) stimulated by epimysial electrodes, Mm. sartorius and rectus femoris (knee extensor) stimulated by neural, bipolar electrodes. Patient's selection criteria were: stable spinal cord lesion between T7 and T11, minimum 1 year after the accident without deformity of the spine, the muscle groups for locomotion responding to external FES with the EXOSTIM programmer with the same programme used later for the neuroprosthesis. Two paraplegic male patients, T8, 38 and 31 years old respectively, were operated on by an international group of surgeons according to the protocol in 09/1999, respectively 7/2000. The postop. course was uneventful. Because the threshold of the primary implant was too low regarding scare tissue around the electrodes, this implant was changed in 01/2000 and worked perfectly. Both patients are happy with the success of the novel treatment modalities.

Balance and stabilization capability of paraplegic wheelchair athletes.

The orientation of paraplegic athletes toward adapted sport activities required good knowledge of their functional characteristics. Wheelchair locomotion, especially for highly dynamic situations, poses the problem of trunk equilibrium management and head stabilization. The study aimed at designing a quantitative method to assess the ability of paraplegics to obtain trunk balance under dynamic stresses, and to analyze the various balance strategies, according to the spinal lesion level of the subjects. High (HPA) and low (LPA) paraplegic athletes were subjected to four series of antero-posterior stresses of increasing intensity, generated by an oscillating platform. By means of a computerized video-based movement analyzer, acceleration in the saggittal plane was measured at four different spinal level and, for each one, a damping factor was determined. This factor, computed at the head level, appeared to be representative of the subjects' ability to maintain balance. We attempted to differentiate balance strategies in the LPA and HPA groups through analysis of the relative contributions to damping of the thoracic and cervical spinal segments. The first results show an increasing tendency of neck reflex stiffening according to the neurological level.

[An experimental study of the results of compression of the growth plate (author's transl)]. / Comportement mécanique du cartilage de conjugaison. Etude expérimentale en compression (1).

The authors, using external fixators, have applied measured compression forces through the growth plate of the lower end of the femur in rabbits. They have calculated the degree of compression necessary to slow down or to stop growth. It was shown that growth may become normal following release of the compression provided that the compression was not excessive. An histological study was conducted with showed lesions varying from a simple diminution in the height of the cellular columns to the development of bony bridges depending on the intensity of the compression.

[Scapulohumeral arthrodesis by combined external and internal fixation. A biomechanical, technical and clinical study]. / Arthrodése scapulo-humérale par fixation combinée externe et interne. Etude biomécanique, technique et clinique.

The indications for arthrodesis of the shoulder are controversial and limited and fusion is difficult to achieve, as is shown by the number of methods described in the literature. Since 1970, the authors have used combined internal and external fixation for arthrodesis of the shoulder. From a biomechanical study of arthrodesed shoulders, an attempt has been made to define the best combination of fixation. Three progressively more complex methods combining intra-articular fixation with a Hoffmann external fixator in compression have been tested. The ideal method combines transverse double scapulo-humeral screws with a vertical acromio-humeral screw. The addition of a bony subacromial strut controls the shearing effects arising from the application of the fixator in compression and also provides an upper site of fusion. In 14 arthrodeses using combined internal and external fixation analysed with a two to sixteen year follow-up, acromio-humeral fixation has been used in 11 cases with 10 primary successes and in 3 cases triple screw fixation has given very rapid fusion without the need for spica immobilisation.

[Dilator muscles of the pharynx and their implication in the sleep apnea syndrome of obstructive type. Review of the literature]. / Les muscles dilatateurs du pharynx et leur implication dans le syndrome d'apnée du sommeil de type obstructif. Revue de la littérature.

Pathophysiology of the obstructive sleep apnea syndrome shows three components: intra and peripharyngeal obstacles, excessive pharyngeal wall compliance and upper airway dilator muscle dysfunction. The intent of this paper is to provide an overview of the anatomy, histology, physiology and pathophysiology of the upper airway dilator muscles based on previously published articles. The upper airway dilator muscles can be separated in three different systems, main and accessory dilators, local and regional. They act in synergy. Their contraction occurs at the beginning of inspiration, thus maintaining opened the pharyngeal lumen through inspiration. Their action is modulated by several chemo or physical stimuli. In some apneic patients, these muscles demonstrate a dysfunction: hyperactivity during wakefulness, electromyogram wave amplitude reduced, delayed contraction during sleep and abnormal response to stimuli. This dysfunction might be due to neuromuscular histological abnormalities, a "fatigue" phenomenon or a central nervous command abnormality. Current explorations underlining an upper airway dilator muscle dysfunction will enable practitioners to decide which treatment is best and understand therapeutical failures; it will also help develop new therapeutical techniques such as functional electrical stimulation of the hypoglossal nerve/upper airway dilator muscles.

[Modern techniques of restoration of locomotion in paralyzed persons]. / Les techniques modernes de restauration de la locomotion chez les personnes paralysées.

The destruction of neurons, in the nervous system, is an irreversible process, which makes difficult the therapy of lesions. The natural regeneration of nervous fibers has a different expression in peripheral and central nervous system. The biological research represents a long term hope. The only realistic approach at the moment is the Functional Electrostimulation of infralesional nerves and muscles by implanted neuroprosthesis.

[Determination of the instantaneous center of rotation of the shoulder using the ELITE system. Application to the study of normal and pathological abduction]. / Détermination du centre instantané de rotation de l'épaule par le système ELITE. Application à l'étude de l'abduction normale et pathologique.

The authors determined the in vivo displacement of the instantaneous center of rotation (ICR) of the shoulder from data supplied by an optoelectronic system (ELITE System) which uses a specifically designed software program to achieve 3-dimensional analysis of abduction. The study involved 10 control subjects and 20 patients suffering from a periarticular disorder of the shoulder capsule retraction in 10 cases and rotator cuff tears before and after rehabilitation in 10 cases. This method provides an objective assessment of humeral head misalignment in relation to the glenoid cavity induced by the periarticular shoulder disorder and of the realignment achieved through rehabilitation. The proposed ICR calculation technique is entirely harmless for the patient in (particular because it requires no radiation analysis).

Bone loss in spinal cord-injured patients: from physiopathology to therapy.

STUDY DESIGN: Review article on bone metabolism and therapeutic approach on bone loss in patients with spinal cord injury (SCI). OBJECTIVE: The first part aims to describe the process of bone demineralization and its effects on bone mass in patients with SCI. The second part describes and discusses the therapeutic approaches to limiting the alteration in bone metabolism related to neurological lesions. SETTING: Propara Rehabilitation Center, Montpellier, France. RESULTS: During the first 24 months postinjury, demineralization occurs exclusively in the sublesional areas and predominantly in weight-bearing skeletal sites such as the distal femur and proximal tibia, both of which are trabecular-rich sites. Reduced bone mass, in association with a modified bone matrix property and composition, is very likely at the origin of pathological fractures after minor trauma to which these patients are frequently exposed. Since these fractures may be asymptomatic yet may lead to complications, preventing and managing 'neurological osteoporosis' remains a considerable challenge. Two main approaches are considered: the first consists in applying a mechanical stimulus to the bone tissue by standing, orthotically aided walking or functional electrical stimulation (FES). The second uses medications, particularly antiresorptive drugs such as calcitonin or diphosphonates. CONCLUSION: To develop well-adapted treatments, a more precise understanding of bone loss etiology is needed. The current rehabilitation programs are based on the idea that the bone physiological changes observed in patients with SCI are due to immobility, but results indicate that alterations inherent to neurological damage may play an even greater role in inducing osteoporosis.

[Anatomy and pathophysiology of deglutition disorders]. / Anatomie und Pathophysiologie von Schluckstörungen.

In the nervous system there are many automatized functions that require multilevel control. Some of them are more important because of their link with some vital functions. Only two are crucial to survival: respiration and the pumping of the heart. Swallowing is integrated within the respiratory system, explaining the need for great reliability and justifying the complexity of the organization described. The progress of medical imaging techniques has created new conditions for practicing radiologists, who need to know much more anatomy than in the past. Therefore, it is easier to learn anatomical details if there details are understood as part of an intelligent construction. We hope to have been able to demonstrate that swallowing is one good example of the real competency of the constructor of this system.

Clinical results of the triangular external fixation device in serious lesions of the lower extremity.

Several types of external fixation devices exist among which those of Judet, Hoffmann, Wagner and Müller can be picked out, each of which has definite applications. Confronted with difficulty in the use and the defect of mechanical rigidity, we have been led to design a new type of the triangular external fixation device. As open fractures of the limbs in stage II and IV of Duparc and Cauchoix, and pseudoarthrosis infected need a considerable stability in addition to careful surgical treatment, so after a comparative mechanical study, and after codifying the most rigid installation, we have used it on several traffic accident victims.