Maryline Mousny

Computation of spine intervertebral motions in scoliotic patients: a multibody approach

The intervertebral efforts quantification in scoliotic spines, before and after spine arthrodesis, appears to be useful for surgical planning. An increase of 30% of the energetic cost for adolescent idiopathic scoliosis patients (Mahaudens & Mousny 2010), as well as its consequences in ordinary living, suggest that gait is a relevant motion to be considered in our study. The accurate computation of those efforts strongly depends on four pillars as follows: geometrical identification, spine and pelvis kinematics, patient physiology, and muscular forces. The geometrical identification of the spine, using bi-planar X-rays (Figure 1-left), as well as the computation of its kinematics from a limited amount of data (Figure 1-right), has been addressed in previous studies (Abedrabbo et al. 2012, 2014). The present work focuses on the evaluation of the spine kinematics identification during gait, for a scoliotic patient.

Anesthetic management of a child with Ullrich myopathy

To the Editor: A 9-year-old boy was scheduled for surgery to correct bilateral fixed plantar flexion. Because muscular weakness had been observed early in childhood, a muscle biopsy had been performed (result: myopathy), but a skin biopsy finally established the diagnosis of Ullrich’s myopathy (UD), a congenital muscle dystrophy. Preoperative physical examination showed a child with weight of 24 kg and height of 131 cm. Cervical spinal mobility was slightly limited; micrognathism and prominent incisive teeth were present. Creatinine phosphokinase (CK) level was at the upper limit of normal values for our laboratory. Cardiac and pulmonary function tests were normal. The patient had already undergone one general anesthesia in the past (for the muscle biopsy) consisting of total intravenous anesthesia (TIVA) with alfentanil and propofol. After careful positioning, standard monitoring was applied. Peripheral venous was obtained while the patient breathed O2 and N2O (50–50 %) by mask. Induction of anesthesia was performed with sufentanil (0.1 lg/kg) and propofol (3 mg/kg), followed with manual ventilation with sevoflurane. Orotracheal intubation was performed at first attempt (Cormack–Lehane stage 3). Surgery lasted 2 h. A tourniquet was used for each site successively. Core body temperature and capnography remained normal; no significant increase in expired CO2 was noticed when the tourniquets were released. In this surgery, as in the previous one, no muscle relaxant was used. Postoperative analgesia consisted of IV ketorolac, acetaminophen, and piritramide in the pediatric acute care unit (PACU). The postoperative evolution was satisfactory. No clinical signs of rhabdomyolysis (e.g., dark urine) were observed. No significant elevation in the CK levels was observed. The CK increased from 407 U/l before the surgery to 440 U/l after the surgery; the upper normal value of our laboratory is 400 U/l. The clinical diagnosis of UD is based on general muscle weakness, contractures of multiple joints, hyperextensibility of distal joints, and other orthopedic and systemic signs [1, 2]. There is no evidence of cardiac dysfunction, but the diaphragm is often involved early. Tracheal intubation may be difficult because of the combination of micrognathism and contracture of the temporomandibular muscles. When planning anesthesia for a child with a muscle disease, one of the anesthesiologist’s concerns is to limit the risk of inducing a malignant hyperthermia (MH) crisis or rhabdomyolysis. In this case, the risk of MH was estimated to be not greater than in the general population because the familial history was negative and the gene mutations for UD are different and distant from the known mutations of the RYR1 and CACNL1A3 genes associated with MH [3–5]. In conclusion, this case, in addition to the other published cases, shows that halogenated agents can be used safely in children with UD as well as in other congenital muscle dystrophies. I. Grosu (&) D. Truong S. Teodorescu M. Mousny F. Veyckemans Service d’Anesthésiologie, Departments of Anesthesiology and Orthopedics, Cliniques Universitaires Saint Luc, 10 Avenue Hippocrate, 1200 Brussels, Belgium e-mail: irina.grosu@uclouvain.be

Gait in patients with adolescent idiopathic scoliosis. Effect of surgery at 10 years of follow-up

PURPOSE To assess radiological and gait biomechanical changes before, at one and 10 years after surgery in AIS patients. METHODS This clinical prospective study included fifteen adult women (mean[SD] age: 26 [1] years) diagnosed with thoraco-lumbar/lumbar AIS and operated 10 years ago. Clinical, radiological and gait variables, including kinematics, electromyography (EMG), mechanics and energetics were compared between presurgery (S0), 1 year (S1) and 10 years (S2) postsurgery period using a one way repeated measure ANOVA. RESULTS The Cobb angle of the scoliosis curve was reduced by 55% at 1 year postsugery but only by 37% at 10 years postsurgery suggesting a loss of 32% over time. Frontal plumb line C7-S1 distance was significantly improved by surgery (-44%) and remained stable at 10 years postsurgery. Lower limb kinematics was not affected by the surgery at long term. Excessive bilateral activation of lombo-pelvic muscles, observed before surgery, decreased significantly at S1 and S2 period. Mechanical energy increased significantly between S0, S1 and S2 session, without any change for the energetic variables. CONCLUSIONS Between 1 and 10 years post-surgery, thoraco-lumbar/lumbar AIS women showed a few decompensation of the curve without any change of the improved frontal body balance. Lower limbs and pelvic motion, during gait, was not affected by the surgery. But presurgical excessive EMG activity of the lumbo-pelvic muscle and reduced mechanical energy produced to walk get similar to normal patterns. Only the oxygen consumption remained excessive probably due to physical deconditioning or postural instability.

Intervertebral efforts quantification using a multibody dynamics approach: application to scoliosis

Spine surgery planning involves many decisions for which the surgeon has not enough information, and for which biomechanical models might be helpful This has been illustrated by a study carried out at the École Polytechnique de Montréal (Robitaille et al. 2007), which shows a high variability in decision-making in the planning of scoliosis surgery for an experienced group of surgeons This variability is problematic because it could cause complications for the patient such as a revision surgery or an excessive limitation of spine mobility Therefore, a biomechanical model for spine surgery planning might be useful in giving the surgeon sufficient information to propose the best treatment In this context, the intervertebral efforts represent an essential input to help in the diagnosis and subsequently to guide surgical planning of scoliosis.