Gait in adolescent idiopathic scoliosis: energy cost analysis

Abstract

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 4 km/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 (W tot ) 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 (COM b ) is known as the internal work (W int ), whereas additional work, known as external work (W ext ), is needed to accelerate and lift up the COM b relative to the ground. Normally, the COM b goes up and down by 3 cm with every step. Pathological walking usually leads to an increase in W tot (often because of increased vertical displacement of the COM b ), 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. Fiftyfour 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] B 20°), 13 were in scoliosis group 2 (20°\ Cb \ 40°), and 16 were in scoliosis group 3 (Cb C 40°). 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 4 km h -1 . Movements of the limbs were followed by six infrared cameras, which tracked markers fixed on the body. W int was calculated from the kinematics. The movements of the COM b were derived from the ground reaction forces, and W ext was calculated from the force signal. W tot was equal to W int ? W ext . Oxygen consumption _ VO 2 À Á was measured with a mask to calculate energetic cost (C) and muscular efficiency (W tot /C). Statistical comparisons between the groups were performed using an analysis of variance (ANOVA). The external work (W ext ) and internal work (W int ) were both reduced from 7 to 22% as a function of the severity of the scoliosis curve. Overall, the total muscular mechanical work (W tot ) was reduced from 7% to 13% in the scoliosis patients. Within scoliosis groups, the W ext for the group 1 (Cb C 20°) and 2 (20 B Cb B 40°) was significantly different from group 3 (Cb C 40°). No significant differences were observed between scoliosis groups for the W int . The W tot did not showed any significant difference between scoliosis groups except between group 1 and 3. The energy cost and _ VO 2 were increased by around 30%. As a result Muscle efficiency was significantly decreased by 23% to 32%, but no significant differences related to the severi...

Energetics and mechanics of walking in patients with chronic low back pain and healthy matched controls

“…The sample size was based on a previous study (Mahaudens et al 2009) that reported a net C w of 2.4 (0.4) J kg −1 m −1 and 1.8 (0.3) J kg −1 m −1 in adolescents with or without idiopathic scoliosis, respectively. To detect a 0.6 J kg −1 m −1 difference with a standard deviation of 0.4 J kg −1 m −1 , 90 % power and at the 5 % significance level, a minimum of 11 participants in both study groups was required.…”

“…In several pathologic conditions, gait pattern alterations are associated with an increased energetic cost of walking (Mahaudens et al 2009;Bernardi et al 1999). In patients with cLBP, the aforementioned adaptations (altered trunk-pelvis coordination, increased muscle activation and stronger cognitive regulation of gait) may also cause an augmented production of mechanical work and an increased metabolic demand.…”

The 3D path of body centre of mass during adult human walking on force treadmill

“…Substantial equivalence between the kinematics of ground and treadmill walking has been already reported in the literature (Riley et al, 2007). Yet, to the authors' knowledge, the GAFT approach has been reported in just one clinical article (Mahaudens et al, 2009). At least two explanations may be proposed.…”

Prospective evaluation of physical activity in patients with idiopathic scoliosis or kyphosis receiving brace treatment

“…During brace treatment, AIS and AK patients do not generally experience pain that might negatively influence their habitual activities. It can be assumed that modified gait in AIS patients, demonstrated in the laboratory setting [19,46], which is accompanied by increased oxygen consumption [20], restricts everyday physical activities in adolescent patients.…”