Philippe Mahaudens

Gait in adolescent idiopathic scoliosis: kinematics and electromyographic analysis

Adolescent idiopathic scoliosis (AIS) is a progressive growth disease that affects spinal anatomy, mobility, and left-right trunk symmetry. Consequently, AIS can modify human locomotion. Very few studies have investigated a simple activity like walking in a cohort of well-defined untreated patients with scoliosis. The first goal of this study is to evaluate the effects of scoliosis and scoliosis severity on kinematic and electromyographic (EMG) gait variables compared to an able-bodied population. The second goal is to look for any asymmetry in these parameters during walking. Thirteen healthy girls and 41 females with untreated AIS, with left thoracolumbar or lumbar primary structural curves were assessed. AIS patients were divided into three clinical subgroups (group 1xa0<xa020°, group 2 between 20 and 40°, and group 3xa0>xa040°). Gait analysis included synchronous bilateral kinematic and EMG measurements. The subjects walked on a treadmill at 4xa0km/h (comfortable speed). The tridimensional (3D) shoulder, pelvis, and lower limb motions were measured using 22 reflective markers tracked by four infrared cameras. The EMG timing activity was measured using bipolar surface electrodes on quadratus lumborum, erector spinae, gluteus medius, rectus femoris, semitendinosus, tibialis anterior, and gastrocnemius muscles. Statistical comparisons (ANOVA) were performed across groups and sides for kinematic and EMG parameters. The step length was reduced in AIS compared to normal subjects (7% less). Frontal shoulder, pelvis, and hip motion and transversal hip motion were reduced in scoliosis patients (respectively, 21, 27, 28, and 22% less). The EMG recording during walking showed that the quadratus lumborum, erector spinae, gluteus medius, and semitendinosus muscles contracted during a longer part of the stride in scoliotic patients (46% of the stride) compared with normal subjects (35% of the stride). There was no significant difference between scoliosis groups 1, 2, and 3 for any of the kinematic and EMG parameters, meaning that severe scoliosis was not associated with increased differences in gait parameters compared to mild scoliosis. Scoliosis was not associated with any kinematic or EMG left–right asymmetry. In conclusion, scoliosis patients showed significant but slight modifications in gait, even in cases of mild scoliosis. With the naked eye, one could not see any difference from controls, but with powerful gait analysis technology, the pelvic frontal motion (right–left tilting) was reduced, as was the motion in the hips and shoulder. Surprisingly, no asymmetry was noted but the spine seemed dynamically stiffened by the longer contraction time of major spinal and pelvic muscles. Further studies are needed to evaluate the origin and consequences of these observations.

Gait in adolescent idiopathic scoliosis: energy cost analysis.

Walking is a very common activity for the human body. It is so common that the musculoskeletal and cardiovascular systems are optimized to have the minimum energetic cost at 4xa0km/h (spontaneous speed). A previous study showed that lumbar and thoracolumbar adolescent idiopathic scoliosis (AIS) patients exhibit a reduction of shoulder, pelvic, and hip frontal mobility during gait. A longer contraction duration of the spinal and pelvic muscles was also noted. The energetic cost (C) of walking is normally linked to the actual mechanical work muscles have to perform. This total mechanical work (Wtot) can be divided in two parts: the work needed to move the shoulders and lower limbs relative to the center of mass of the body (COMb) is known as the internal work (Wint), whereas additional work, known as external work (Wext), is needed to accelerate and lift up the COMb relative to the ground. Normally, the COMb goes up and down by 3xa0cm with every step. Pathological walking usually leads to an increase in Wtot (often because of increased vertical displacement of the COMb), and consequently, it increases the energetic cost. The goal of this study is to investigate the effects of scoliosis and scoliosis severity on the mechanical work and energetic cost of walking. Fifty-four female subjects aged 12 to 17 were used in this study. Thirteen healthy girls were in the control group, 12 were in scoliosis group 1 (Cobb angle [Cb]xa0≤xa020°), 13 were in scoliosis group 2 (20°xa0<xa0Cbxa0<xa040°), and 16 were in scoliosis group 3 (Cbxa0≥xa040°). They were assessed by physical examination and gait analysis. The 41 scoliotic patients had an untreated progressive left thoracolumbar or lumbar AIS. During gait analysis, the subject was asked to walk on a treadmill at 4xa0kmxa0h−1. Movements of the limbs were followed by six infrared cameras, which tracked markers fixed on the body. Wint was calculated from the kinematics. The movements of the COMb were derived from the ground reaction forces, and Wext was calculated from the force signal. Wtot was equal to Wintxa0+xa0Wext. Oxygen consumption

Idiopathic scoliosis and breast asymmetry

left( {dot{V}{text{O}}_{2} } right)

Effects of short-term brace wearing on the pendulum-like mechanism of walking in healthy subjects

was measured with a mask to calculate energetic cost (C) and muscular efficiency (Wtot/C). Statistical comparisons between the groups were performed using an analysis of variance (ANOVA). The external work (Wext) and internal work (Wint) were both reduced from 7 to 22% as a function of the severity of the scoliosis curve. Overall, the total muscular mechanical work (Wtot) was reduced from 7% to 13% in the scoliosis patients. Within scoliosis groups, the Wext for the group 1 (Cbxa0≥xa020°) and 2 (20xa0≤xa0Cbxa0≤xa040°) was significantly different from group 3 (Cbxa0≥xa040°). No significant differences were observed between scoliosis groups for the Wint. The Wtot did not showed any significant difference between scoliosis groups except between group 1 and 3. The energy cost and

Are the medio-lateral joint forces in the lower limbs different between scoliotic and healthy subjects during gait?

dot{V}{text{O}}_{2}

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

were increased by around 30%. As a result Muscle efficiency was significantly decreased by 23% to 32%, but no significant differences related to the severity of the scoliosis were noted. This study shows that scoliosis patients have inefficient muscles during walking. Muscle efficiency was so severely decreased that it could be used as a diagnostic tool, since every scoliosis patient had an average muscle efficiency below 27%, whereas every control had an average muscle efficiency above 27%. The reduction of mechanical work found in scoliotic patients has never been observed in any pathological gait, but it is interpreted as a long term adaptation to economize energy and face poor muscle efficiency. With a relatively stiff gait, scoliosis patients also limit vertical movement of the COMb (smoothing the gait) and consequently, reduce Wext and Wint. Inefficiency of scoliosis muscles was obvious even in mild scoliosis (group 1, Cbxa0<xa020°) and could be related to the prolonged muscle contraction time observed in a previous study (muscle co-contraction).