Lateral ankle sprain alters postural control in bipedal stance--part 1: restoration over the 30 days following the injury.

The time evolution of the postural behavior of 23 lateral ankle sprain patients (degrees I and II) were evaluated 14 h and 10 and 30 days on average after their injury and compared with those of 30 age-matched healthy individuals. The patients were tested with separate measurements of the reaction forces under each limb to highlight the possible compensatory mechanisms between the sound and the injured legs. Their postural behavior in bipedal stance was characterised by a weight-bearing asymmetry with more weight on the sound leg and an asymmetry of the postural stabilisation mechanisms, which are limited and perturbed under the injured leg. Pain appears to be the main factor for explaining these postural asymmetries. Despite these asymmetries, the patients were nonetheless more unstable than the individuals constituting the group control. Ten days later, only the weight-bearing asymmetry was still observed whereas 30 days later, the postural behavior was totally normal once again. Lateral ankle sprain perturbs the contribution of the injured leg in postural stabilisation, inducing a larger involvement of the sound leg in the postural stability process. These characteristics are largely reduced 10 days after the injury.

Lateral ankle sprain alters postural control in bipedal stance: part 2 sensorial and mechanical effects induced by wearing an ankle orthosis.

To investigate the effects induced by wearing an orthosis during the rehabilitation process, 23 ankle sprain patients (degrees I and II) were evaluated in three conditions (reference, with an elastic compression stocking and with an orthosis), 14 h, 10 and 30 days on average after their injury and compared with those of 30 age-matched healthy individuals. The patients were tested with separate measurements of the reaction forces under each limb to highlight the possible compensatory mechanisms between the sound and the injured legs. Their postural stability was enhanced during unilateral orthosis wear, explained by a bilateral effect involving both feet. Wearing a compression stocking induced comparably mild intermediate effects compared with the effects observed with the orthosis. These effects were constant throughout the next month. Following lateral ankle sprain, wearing an orthosis allows patients to improve postural function a few hours after the injury to 1 month later. Only cutaneous pressure intervening without mechanical maintenance induced mild effects, indicating that orthosis effects on postural control could partly result from its sensorial stimulation. It, therefore, seems relevant to prescribe orthosis wear for at least 1 month.

Biomechanical analysis of postural control of persons with transtibial or transfemoral amputation.

OBJECTIVE: In human subjects, leg amputation impairs upright quiet-stance control. The inability to exert appropriate force reactions under the amputated leg and a slight weight-bearing asymmetry cause the amputee to develop compensatory mechanisms through the sound leg. This study is aimed at assessing these mechanisms and the influence of the level of amputation. DESIGN: The postural strategies of transtibial and transfemoral amputees for maintaining quiet stance were investigated using a dual-force platform. With this device, mean body weight distribution and plantar and resultant center of pressure trajectories can be measured and used to assess the likely compensatory mechanisms. RESULTS: Compensatory strategies were found in both transtibial and transfemoral groups, with a forward shift of the mean positions of the center of pressure under the amputated leg and greater resultant center of pressure displacements appearing along the anteroposterior axis, respectively. The transfemoral group presents a larger center of pressure displacements under the amputated leg than the transtibial group. CONCLUSION: These data emphasize the role played by the differences between the center-of-pressure magnitudes intervening under the sound and amputated legs and the size of the prosthesis-stump contact area in these postural strategies.

Foot varus in stroke patients: muscular activity of extensor digitorum longus during the swing phase of gait.

BACKGROUND: Hemiparetic patients often present an abnormal leg muscles balance that can lead to foot deformities like equinovarus or varus. OBJECTIVE: To assess whether a muscle imbalance between tibialis anterior and extensor digitorum longus was associated with a varus deformity of the foot during the swing phase of gait in stroke patients. METHODS: Twenty hemiparetic patients presenting a foot varus during the swing phase of gait were compared to 16 healthy subjects. Gait was analyzed by video recording and by surface electromyography. Duration and magnitude of electromyographic signal were collected for tibialis anterior and extensor digitorum longus. Presence of an activity of the calf muscles during the swing phase was also evaluated. RESULTS: Hemiparetic patients exhibited more often premature activity of the calf muscles (p<0.05) and greater duration and amplitude asymmetry between tibialis anterior and extensor digitorum longus (p<0.05). These asymmetries were explained by a decrease in extensor digitorum longus activity (p<0.05). CONCLUSIONS: The activity of extensor digitorum longus muscle during the swing phase of gait is important to balance the foot in the frontal plane. The activation of that muscle should be included in rehabilitation programs.

[Immediate effects of physiotherapy session of lower limb by balneotherapy on postural control]. / Effets immédiats de séances de rééducation des membres inférieurs par balneotherapie sur le contrôle de l'équilibre.

OBJECTIVE: The aim of this study was to compare the immediate effects of standard physiotherapy (S) and balneotherapy (B) on the postural capacity of subjects with lower-limb injuries. METHODS: The postural sway of 12 voluntary subjects was evaluated before (REF1 and REF2) and after two different physiotherapy sessions performed in the swimming pool (B) or under (S). The centre of pressure (CP) trajectory was recorded by use of a force platform. CP displacements in the mediolateral and anteroposterior axes were then separated into two elementary superimposed components: the horizontal motion of the centre of gravity (CG) and the difference between the CP and the vertical projection of the CG (CP-CG). The amplitude of the latter component (CP-CG) is thought to express neuromuscular activity. All trajectories were then analysed in terms of classical and frequency parameters. RESULTS: Postural sway did not differ before and after the physiotherapy sessions. Following both sessions, the mean CG velocity decreased significantly (P<0.5). The area of CP-CG trajectory was diminished solely by the aquatic exercise (P<0.5) and was associated with decreased amplitude of motion along the anteroposterior axis (P<0.05), which suggests decreased neuromuscular activity to maintain posture. CONCLUSION: Interestingly, decreased motion was observed along the anteroposterior axis, which corresponds to ankle movements. Exercising lower-limb muscles under water could reinforce proprioceptive input, resulting in a better postural control.