Estimation of external contact loads using an inverse dynamics and optimization approach: general method and application to sit-to-stand maneuvers.

This paper presents a general method to estimate unmeasured external contact loads (ECLs) acting on a system whose kinematics and inertial properties are known. This method is dedicated to underdetermined problems, e.g. when the system has two or more unmeasured external contact wrenches. It is based on inverse dynamics and a quadratic optimization, and is therefore relatively simple, computationally cost effective and robust. Net joint loads (NJLs) are included as variables of the problem, and thus could be estimated in the same procedure as the ECL and be used within the cost function. The proposed method is tested on human sit-to-stand maneuvers performed holding a handle with one hand, i.e. asymmetrical movements with multiples external contacts. Three sets of measured and unmeasured contact load components and three cost functions are considered and simulated results are compared to experimental data. For the population and movement studied, better results are obtained for a least-square sharing between actuated degrees-of-freedom of the relative motor torques (motor torques normalized by the maximal torque production capacity). Moreover, the number of unknown ECL components does not significantly influence the results. In particular, measuring only the vertical force under the seat lead to a relatively correct estimation of the ECL and NJT: not only the values of R% were small (about 10% for the feet ECL and 20% for the NJT), but the influence of an experimental parameters (the Seat Height) was also correctly predicted.

The piriformis muscle syndrome: an exploration of anatomical context, pathophysiological hypotheses and diagnostic criteria.

INTRODUCTION: The piriformis muscle syndrome (PMS) has remained an ill-defined entity. It is a form of entrapment neuropathy involving compression of the sciatic nerve by the piriformis muscle. Bearing this in mind, a medical examination is likely to be suggestive, as a classical range of symptoms corresponds to truncal sciatica with frequently fluctuating pain, initially in the muscles of the buttocks. PATHOPHYSIOLOGICAL HYPOTHESES: The piriformis muscle is biarticular, constituting a bridge in front of and below the sacroiliac joint and behind and above the coxo-femoral joint. It is essentially a lateral rotator but also a hip extensor, and assumes a secondary role as an abductor. Its action is nonetheless conditioned by the position of the homolateral coxo-femoral joint, and it can also function as a hip medial rotator, with the hip being flexed at more than 90°. The main clinical manoeuvres are derived from these types of biomechanical considerations. For instance, as it is close to the hip extensors, the piriformis muscle is tested in medial rotation stretching, in resisted contraction in lateral rotation. On the other hand, when hip flexion surpasses 90°, the piriformis muscle is stretched in lateral rotation, and we have consequently laid emphasis on the manoeuvre we have termed Heel Contra-Lateral Knee (HCLK), which must be prolonged several tens of seconds in order to successfully reproduce the buttocks-centred and frequently associated sciatic symptoms. CONCLUSION: A PMS diagnosis is exclusively clinical, and the only objective of paraclinical evaluation is to eliminate differential diagnoses. The entity under discussion is real, and we favour the FAIR, HCLK and Freiberg stretching manoeuvres and Beatty's resisted contraction manoeuvre.

Piriformis muscle syndrome: diagnostic criteria and treatment of a monocentric series of 250 patients.

OBJECTIVES: Piriformis Muscle Syndrome (PMS) is caused by sciatic nerve compression in the infrapiriformis canal. However, the pathology is poorly understood and difficult to diagnose. This study aimed to devise a clinical assessment score for PMS diagnosis and to develop a treatment strategy. MATERIAL AND METHODS: Two hundred and fifty patients versus 30 control patients with disco-radicular conflict, plus 30 healthy control subjects were enrolled. A range of tests was used to produce a diagnostic score for PMS and an optimum treatment strategy was proposed. RESULTS: A 12-point clinical scoring system was devised and a diagnosis of PMS was considered 'probable' when greater or equal to 8. Sensitivity and specificity of the score were 96.4% and 100%, respectively, while the positive predictive value was 100% and negative predictive value was 86.9%. Combined medication and rehabilitation treatments had a cure rate of 51.2%. Hundred and twenty-two patients (48.8%) were unresponsive to treatment and received OnabotulinumtoxinA. Visual Analogue Scale (VAS) results were 'Very good/Good' in 77%, 'Average' in 7.4% and 'Poor' in 15.6%. Fifteen of 19 patients unresponsive to treatment underwent surgery with 'Very good/Good' results in 12 cases. CONCLUSIONS: The proposed evaluation score may facilitate PMS diagnosis and treatment standardisation. Rehabilitation has a major role associated in half of the cases with botulinum toxin injections.

A French observational study of botulinum toxin use in the management of children with cerebral palsy: BOTULOSCOPE.

BACKGROUND: Dystonia and spasticity are common symptoms in children with Cerebral Palsy (CP), whose management is a challenge to overcome in order to enable the harmonized development of motor function during growth. AIM: To describe botulinum toxin A (BTX-A) use and efficacy as a treatment of focal spasticity in CP children in France. METHODS: This prospective observational study included 282 CP children mostly administered according to French standards with BTX-A in lower limbs. Realistic therapeutic objectives were set with parents and children together before treatment initiation and assessed using the Visual Analogue Scale (VAS). Child management was recorded and the efficacy of injections was assessed during a 12-month follow-up period by physicians (Modified Ashworth Scale, joint range of motion, Physician Rating Scale, Gillette Functional Assessment Questionnaire and Gross Motor Function Measure-66) and by patients/parents (Visual Analogue Scale). RESULTS: BTX-A treatment was administered in different muscle localizations at once and at doses higher than those recommended by the French Health Authorities. Children were treated in parallel by physiotherapy, casts and ortheses. Injections reduced spasticity and improved joint range of motion, gait pattern and movement capacity. Pain was reduced after injections. BTX-A administration was safe: no botulism-like case was reported. The log of injected children who were not included in the study suggested that a large population could benefit from BTX-A management. CONCLUSIONS: We showed here the major input of BTX-A injections in the management of spasticity in CP children. The results are in favor of the use of BTX-A as conservative safe and efficient treatment of spasticity in children, which enables functional improvement as well as pain relief.

Analysis of return to competition and repeat rupture for 298 anterior cruciate ligament reconstructions with patellar or hamstring tendon autograft in sportspeople.

OBJECTIVES: To establish the influence of the type of surgical technique, competitive level, type of sport and the time before returning to competition on the reinjury rate after anterior cruciate ligament (ACL) surgery. METHODS: The authors followed-up 540 competitive sportspeople who had undergone ACL surgery via patellar or hamstring tendon autograft (HTA) techniques in 2003 and 2004. The sportspeople (all of whom had competed at a regional or higher level) were asked to fill out a questionnaire during their fourth postoperative year. RESULTS: The 298 respondees (reply rate: 55.1%) had the same characteristics as the initial (operated) population. The reinjury rates after HTA and patellar tendon autograft (PTA) were 12.7 and 6.1%, respectively. There was no statistically significant difference between these two values (P=0.14). Age and gender were not correlated with the frequency of reinjury. The reinjury rate rose slightly with increasing competitive level (regional level: 8.1%; national level: 10.4%; international level: 12.5%) but these differences were not statistically significant. Soccer had the highest reinjury rate (20.8%). Regardless of the surgical technique, sportspeople returning to competition within seven months of surgery had a greater risk of reinjury than those returning after this time point (15.3 versus 5.2%, P=0.014). The risk dropped from 13.9 to 2.6% (P=0.047) for PTA and from 16.6 to 7.6% (P=0.2) for HTA. Of the four reinjuries in sportspeople returning to competition with the first six months postoperative, three occurred within one month of resumption. CONCLUSION: Post-HTA reinjury rates are higher than post-PTA rates but the difference is not statistically significant. For sportspeople at a regional or higher level, the time interval before the return to competition has an influence on the risk of reinjury.

[Lower urinary tract dysfunction and herniated disk]. / Troubles vésico-sphinctériens et hernies discales.

Lower urinary tract dysfunction related to herniated disk can raise complex diagnostic and management problems. This article reviews the two main clinical situations encountered: documented lower urinary tract dysfunction in a context of cauda equina syndrome secondary to herniated disk and lower urinary tract dysfunction representing the only clinical sign of herniated disk with no other alteration of the neurological examination. Regardless of the neurological signs, urodynamic assessment is essential to characterize any lower urinary tract dysfunction and to determine the modalities of long-term surveillance.

Which screening strategy using BMD measurements would be most cost effective for hip fracture prevention in elderly women? A decision analysis based on a Markov model.

INTRODUCTION: Hip fractures are responsible for excessive mortality, decreasing the 5-year survival rate by about 20%. From an economic perspective, they represent a major source of expense, with direct costs in hospitalization, rehabilitation, and institutionalization. The incidence rate sharply increases after the age of 70, but it can be reduced in women aged 70-80 years by therapeutic interventions. Recent analyses suggest that the most efficient strategy is to implement such interventions in women at the age of 70 years. As several guidelines recommend bone mineral density (BMD) screening of postmenopausal women with clinical risk factors, our objective was to assess the cost-effectiveness of two screening strategies applied to elderly women aged 70 years and older. METHODS: A cost-effectiveness analysis was performed using decision-tree analysis and a Markov model. Two alternative strategies, one measuring BMD of all women, and one measuring BMD only of those having at least one risk factor, were compared with the reference strategy "no screening". Cost-effectiveness ratios were measured as cost per year gained without hip fracture. Most probabilities were based on data observed in EPIDOS, SEMOF and OFELY cohorts. RESULTS: In this model, which is mostly based on observed data, the strategy "screen all" was more cost effective than "screen women at risk." For one woman screened at the age of 70 and followed for 10 years, the incremental (additional) cost-effectiveness ratio of these two strategies compared with the reference was 4,235 euros and 8,290 euros, respectively. CONCLUSION: The results of this model, under the assumptions described in the paper, suggest that in women aged 70-80 years, screening all women with dual-energy X-ray absorptiometry (DXA) would be more effective than no screening or screening only women with at least one risk factor. Cost-effectiveness studies based on decision-analysis trees maybe useful tools for helping decision makers, and further models based on different assumptions should be performed to improve the level of evidence on cost-effectiveness ratios of the usual screening strategies for osteoporosis.

Extra- and intramuscular nerve supply of the muscles of the anterior antebrachial compartment: applications for selective neurotomy and for botulinum toxin injection.

Hypertonia of the upper limb due to spasticity causes pronation of the forearm and flexion of wrist and fingers. Nowadays this spasticity is often treated with injections of botulinum toxin and sometimes with selective fascicular neurotomy. To correctly perform this microsurgical technique, it is necessary to get precise knowledge of the extramuscular nerve branching in order to be better able to select the motor branches which supply the muscles involved in spasticity. The same knowledge is required for botulinum toxin injections which must be made as near as possible to the zones where intramuscular nerve endings are the densest, which is also where neuromuscular junctions are the most numerous. Thus, it is necessary to better know these zones, but their knowledge remains today imprecise. The muscles of the anterior compartment of 30 forearms were dissected, first macroscopically, then microscopically, to study the extra- and intramuscular nerve supply and the distribution of terminal nerve ramifications. The results were then linked to surface topographical landmarks to indicate the precise location of motor branches for each muscle with the aim of proposing appropriate surgical approaches for selective neurotomies. Then for each muscle, the zones with the highest density of nerve endings were divided into segments, thus determining the optimal zones for botulinim toxin injections.

[Topographic and functional anatomy of cranial nerves]. / Atteintes périphériques des nerfs crâniens: anatomie.

This review summarizes the descriptive anatomy of cranial nerves III through XII, starting at their emergence from the neuraxis towards peripheral territories, as well as their functional anatomy. For each pair of cranial nerves, correlations are made between diseases, anatomo-clinical and anatomo-neurophysiological data.

Surface electromyography of nine shoulder muscles in two iron cross conditions in gymnastics.

AIM: The rules of gymnastics impose an element of static strength such as an iron cross (IC) on the rings. For IC training, coaches use a custom made device -- the herdos -- to simulate the conditions of competition. The purpose was to compare muscle activity and coordination during IC performed both on the rings and using herdos. Secondly, we tried to determine whether herdos usage induced functional adaptations of the shoulder muscles. METHODS: Six male gymnasts performed 10 IC in each condition. Surface electromyogram of muscles pectoralis major, latissimus dorsi, teres major, infraspinatus, rhomboideus, trapezius, serratus anterior, biceps brachii, and triceps brachii in the right shoulder were analysed using root-mean-square (RMS), and muscle part's in each condition. Muscle part represents the contribution of each of the 9 shoulder muscles studied in each condition. Total muscle activity (SUM) was also used to compare the 2 conditions. RESULTS: Except for the muscle teres major, the RMS decreases (p<0.05) when using the herdos. The SUM also decreases (p<0.05) when using this device. The muscle parts indicate that the contribution of the muscle latissimus dorsi decreases (p<0.05) when using the herdos. These results suggest that the herdos modified shoulder coordination. But their usage does not seem to induce any functional adaptations of these muscles. CONCLUSIONS: The herdos do not seem to provide a valid method to reproduce the same shoulder coordination as on the rings. Therefore IC training with this special device could be called in question.

"Mesorectum": the surgical value of an anatomical approach.

The quality of total extirpation of the "mesorectum" nowadays determines the prognosis of rectal cancer but the planes of surgical dissection which have been proposed and the anatomical restrictions of this "mesorectum" are sometimes contradictory. The aim of this study was to clarify the relationships of the "mesorectum" with the fascias and nerves of the pelvic cavity to harmonize the plane of dissection in its total extirpation. Four pelvises (2 male, 2 female) harvested from embalmed cadavers were studied by dissection and anatomico-imaging correlation. Two pelvises (1 male, 1 female) were injected with copolymer via the internal iliac and inferior mesenteric arteries. They were then frozen and sectioned sagittally into two hemi-pelvises for the dissection. The two other pelvises were initially studied in 5 mm cuts with CT scanning and magnetic resonance scanning in the sagittal and "transverse oblique" planes. They were then frozen and then cut sagittally into two hemi-pelvises. Each hemi-pelvis was then cut into anatomical sections with an electric saw similar to the radiological cuts: sagittal cuts on the right hemi-pelvis, and "transverse oblique" cuts on the left hemi-pelvis. It was noted that the "mesorectum" was carpeted behind and laterally by a postero-lateral fibrous envelope belonging to the pelvic visceral fascia and in front by a recto-genital membrane of variable nature corresponding to the "Denonvilliers fascia". The postero-lateral fibrous envelope splits into two leaves (anterior and posterior) in front of the sacral concavity and constitutes, lateral to the rectum, the armature of the pelvic plexus. These two leaves delineated the avascular retro-rectal space. The results of the correlations were deceptive. Their use was limited by dilatation of the rectum, which flattened the perirectal fat onto the pelvic walls on all the sections. Nonetheless, the description of the "mesorectum" and the demonstration of its enveloping fascias by dissection allowed the development of a dissection plane for its total extirpation.

[Detrusor-sphincter dyssynergia and botulinum toxin]. / Dyssynergie vésico-sphinctérienne et toxine botulique.

OBJECTIVE: Botulinum toxin (BT) injection into the external urethral sphincter is a promising therapy for neurogenic voiding disorders due to detrusor-sphincter dyssynergia (DSD). However the optimal treatment protocol remains unclear. METHOD: A PubMed reference search and manual bibliography review were performed, along with a search in the Annales de réadaptation et de médecine physique and in the reports of the International French-language Society of Urodynamics and the International Continence Society, which allowed us to select twelve pertinent articles with PubMed, two articles from the Annales and two conference reports. Our analysis gave special emphasis to assessment criteria, application, dosage and BT injection technique. RESULTS: Used for the first time in 1988 in spinal cord injury patients to reduce outflow obstruction due to DSD, BT injections have been shown to be a valuable alternative management of bladder dysfunction with DSD. They have been proposed in neurological patients unable to perform self-catheterisation, after drug failure and before surgery. Parameters for results assessment are mostly clinical (increased free interval between voiding, decreased post-void residual urine volumes), urodynamic (improvement in bladder emptying, increase in functional bladder capacity and decrease in urethral pressure) and electromyographic (denervation of striated urethral sphincter). The literature data regarding type of BT, dosage and protocol vary widely. Duration of action is from 2 to 12 months. Both transurethral and transperineal injections monitored by EMG are equally effective in improving detrusor-sphincter dyssynergia. CONCLUSION: With few side effects and satisfactory medium-term results, BT should be recommended as a component of DSD therapies. We propose a practical method for BT use.

[Sialorrhea, hyperhidrosis and botulinum toxin]. / Hypersialorrhée, hypersudation et toxine botulique.

OBJECTIVE: The first clinical studies indicate that Botox provides effective treatment for hyperhidrosis and sialorrhea. The aim of this work is to sum up current evaluation of this use. METHOD: A systematic literature search was conducted on the Pub Med database, along with on chapters in other publications. The most interesting articles in relation to our own personal experience were chosen. RESULTS: Despite recent use of BT to treat focal hyperhidrosis, there have been numerous publications since 1997. However, the injected areas have not been listed so frequently. Axillary hyperhidrosis has been studied most; it is also in this case and in the case of gustatory sweating that the best results have been obtained. Publications about palmar and especially plantar hyperhidrosis are much rarer, almost anecdotic. It has been demonstrated to a lesser extent that BT injections are effective in these cases. Literature about sialorrhea is just beginning. However, the reduction of the production of saliva following intra parenchymatic injection of toxin into the parotid and submandibular glands, thus rarifying drooling, has been demonstrated. For each of the pathological indications, both the injection techniques and the optimal doses remain to be determined. DISCUSSION: Because BT blocks all cholinergic transmission, including the autonomous nervous system, it was plausible to expect a reduction in sweating and salivation on local injection of the product. In fact, the first publications indicated such efficiency without serious side effects. For hyperhidrosis, there has developed a consensus for making intracutaneous injections only. Of the injections in axillary areas, the palms of the hands, the plantar regions, the face or other cutaneous areas, palmoplantar hyperhidrosis is the least accessible, in any case causes the most technical problems, because of difficulty in pain management. For sialorrhea and the drooling that accompanies certain chronical neurological diseases, BT seems to have very promising effects. However, it has not been precisely determined whether to inject the parotid gland, the submandibular gland, or both. Necessary and sufficient means of targeting are still imprecise. It also remains to be determined the number of sites per gland and the doses to be injected.

[EMG support in botulinum toxin treatment]. / Apport de l'EMG dans l'utilisation de la toxine botulique.

INTRODUCTION: The aim of this work is to sum up how the use of EMG improves BT therapy. METHOD: A systematic review of the literature in the Pub Med computer database, along with a manual biography, allowed us to choose the most synthetic and the most pertinent publications according to our own practical experience. RESULTS: There is no consensus of opinion, but the great majority of authors emphasize the importance of EMG in the different stages of botulinum toxin treatment: before injections, at the time of the injection, and finally during the follow-up after the first injection or after the repeated injections that transient efficiency make necessary. DISCUSSION: A symptomatic therapeutic means recently recognized in focal dystonias and spasticity, BT is injected locally into the muscles to be treated. EMG can be used: at pre-injection for physiopathological evaluation but above all to establish a diagnosis and precise pre-intervention evaluation; at the moment of injection to provide guidance in precise muscle selection and for maximum efficiency with reduced, therefore less costly, doses. It also limits the risk of product diffusion susceptible of causing iatrogenic side effects and/or auto-immunisation resulting in resistance to the toxin; during follow-up, to understand why treatment failed and to look for changes in the dystonia pattern leading to objective re-evaluations and adapted reinjections. Although neglected by some, electrological logistics seem to us, as to many other practitioners who inject, to be a considerably helpful aid, particularly at the moment of injection when targeting the muscle to be treated.

[Acute polyradiculoneuritis during primary herpes simple virus infection]. / Polyradiculoneuropathie aiguë au cours d'une primo-infection à virus Herpès simplex.

The herpes virus family, particularly cytomegalovirus and Epstein-Barr virus, are often associated with acute polyradiculoneuritis (APRN). APRN following primary herpes simplex virus infection is much more uncommon, viral reactivation generally being involved. We report a patient who developed APRN following herpes simplex virus primary infection, probably HSV II.

Anatomical bases of superior gluteal nerve entrapment syndrome in the suprapiriformis foramen.

Observation of a 60 year-old-man with superior gluteal nerve (SGN) entrapment neuropathy in the suprapiriformis foramen encouraged us to explore, through anatomical dissection, the possible morphological etiologies of this condition. Ten SGNs in five embalmed cadavers were dissected via gluteal and pelvic access. The origin, course and distribution of the nervous trunk and its relations were studied. In most cases, the nerve fibers of the SGN arose from ventral branches of L4, L5 and S1 to constitute the nervous trunk in the pelvis, then reached the gluteal area and divided into two branches, cranial and caudal. By running through the suprapiriformis foramen with the cranial gluteal vascular pedicle, the nervous trunk was always up between the superior edge of the piriformis muscle and the greater sciatic notch; rarely some of the nerve fibers went through the muscle. Bone, muscular and vascular morphological factors liable to cause SGN entrapment syndrome, and the circumstances of discovery, were analyzed. The role of hypertrophy of the piriformis muscle, resulting in a narrow suprapiriformis foramen, was confirmed through surgery.