Spine kinematics during gait in paediatric Hereditary Spastic Paraparesis

Background: Many studies already addressed specific gait abnormalities in children affected by Hereditary Spastic Paraparesis (HSP). Some authors investigated the contribution of the upper body to walking pattern, but simplifying trunk and pelvis as two hinged rigid bodies. Recently, we developed a method to detail spinal kinematics in terms of anatomic curvatures and length; we were thus interested in applying such protocol to HSP. Research question: how HSP influences spinal kinematics during gait? Methods: we enrolled ten HSP patients (5–17 years, 8 males) and twelve Healthy Children (HC, 8–16 years, 4 males). Kinematic data were recorded with an optoelectronic system using the LAMB full body marker set, which included three physical markers placed on the spine, supplemented with a virtual one reconstructed on the coccix. Calculations included the spinal length (linear distance from C7 to coccix), the kyphosis and lordosis angles, the trunk tilt and obliquity, the pelvis and the shoulder-pelvis angles, as well as the joint angles of the lower limbs. For each variable, the average value and the range of motion (ROM) were extracted and compared between groups. Results: the ROM of spinal length, the average value and ROM of kyphosis angle and the average value of trunk tilt significantly increased in HSP vs HC. A pathologic "double bump” pattern characterized the pelvic tilt traces, the lordosis angles and, with opposite sign, the kyphosis. Both the average value and ROM of pelvic tilt significantly increased in HSP, while ROM of lower limb angles was reduced. Conclusion: spine kinematics were altered in HSP, who also showed an anterior trunk tilt. Therefore, the trunk should be considered an articulated system and not simplified to a rigid body, a perspective that could be also used in treating gait abnormalities.