Stepping over an obstacle in patients with lumbar spinal stenosis: Trunk and lower extremities of kinematic and muscle activation normalized by double limb support. A preliminary study.

BACKGROUND: Patients with LSS tend to adopt a flexed lumbar posture and trunk position, particularly when stepping over an obstacle, as this activity alters the biomechanical demands placed on the trunk and lower extremities.

OBJECTIVE: To investigate the effects of lumbar spinal stenosis (LSS) on patients' trunk and lower-extremity kinematics, and on activities involving the gluteus medius (GMed) and vastus lateralis (VL).

METHODS: All participants (9 older adult patients with LSS and 11 control subjects) were required to negotiate an obstacle while walking. Trunk and lower-extremity kinematic data and GMed and VL activities were recorded using a synchronized 3D motion capture system and surface electromyography.

RESULTS: The thoracic (12.01∘± 8.82∘ and 16.45∘± 10.80∘) and spinal (9.92∘± 14.03∘ and 5.99∘± 15.94∘) flexion angles of the leading and trailing swing limbs were higher, and the pelvic anterior tilting angle (2.37∘± 7.76∘ and 10.38∘± 8.07∘) was lower in the LSS group than in the control group (p< 0.05). With the exception of toe-off and normalized GMed activities in the contralateral leading limb (p> 0.05), all GMed (256.73 ± 112.22%, 174.00 ± 75.79%, and 270.57 ± 114.45%, respectively) and VL (208.98 ± 124.81%, 182.97 ± 93.23%, 283.91 ± 154.71%, and 394.42 ± 108.94%, respectively) activities of the contralateral leading and trailing swing limb (heel-strike and toe-off normalized activities) were significantly higher in the LSS group than in the control group (p< 0.05).

CONCLUSIONS: Patients with LSS exhibited trunk-flexed postures when stepping over an obstacle, and these trunk alignments placed higher demands on the GMed and VL activities normalized by double-limb support during joint loading in the single-leg stance. These findings support clinical recommendations for regulating the physical activity of obstacle negotiation that may be beneficial in the management of patients with LSS.