Effect of lower limb malalignment in the frontal plane on transverse plane mechanics during gait in young individuals with varus knee alignment.

BACKGROUND: Varus knee alignment has been identified as a risk factor for the progression of medial knee osteoarthritis (OA). This study tested the hypothesis that not only frontal plane kinematics and kinetics but also transverse plane lower extremity mechanics during gait are affected by varus malalignment of the knee. METHODS: Eighteen, otherwise healthy children and adolescents with varus malalignment of the knee were studied to examine the association between static varus malalignment and functional gait parameters. Kinematic data were collected using a Vicon motion capture system (Vicon Motion Systems, Oxford, UK). Two AMTI force plates (Advanced Mechanical Technology, Inc., Watertown, MA, USA) were used to collect kinetic data. RESULTS: The results indicated that changes in transverse plane mechanics occur concomitantly with changes in knee malalignment in the frontal plane. A mechanical consequence of varus knee malalignment is obviously an increased endorotation of the foot (internal foot placement) and an increased internal knee rotation (tibia rotation) during stance phase. The linear correlation between the maximum external knee adduction moment in terminal stance and the internal knee rotation in terminal stance (r=0.823, p<0.001) shows that this transverse plane gait mechanics is directly in conjunction with intrinsic compressive load on the medial compartment during gait. CONCLUSIONS: Understanding factors that influence dynamic knee joint loading in healthy, varus malaligned knees may help us to identify risk factors that lead to OA. Thus, three-dimensional gait analysis could be used for clinical prognoses regarding the onset or progression of medial knee OA.

Does excessive flatfoot deformity affect function? A comparison between symptomatic and asymptomatic flatfeet using the Oxford Foot Model.

Treatment of asymptomatic flexible flatfeet is a subject of great controversy. The purpose of this study was to examine foot function during walking in symptomatic (SFF) and asymptomatic (ASFF) flexible flatfeet. Thirty-five paediatric and juvenile patients with idiopathic flexible flatfeet were recruited from an orthopaedic outpatient department (14 SFF and 21 ASFF). Eleven age-matched participants with typically developing feet served as controls (TDF). To study foot function, 3D multi-segment foot kinematics and ankle joint kinetics were captured during barefoot gait analysis. Overall, alterations in foot kinematics in flatfeet were pronounced but differences between SFF and ASFF were not observed. Largest discriminatory effects between flatfeet and TDF were noticed in reduced hindfoot dorsiflexion as well as in increased forefoot supination and abduction. Upon clinical examination, restrictions in passive dorsiflexion in ASFF and SFF were significant. During gait, the hindfoot in flatfeet (both ASFF and SFF) was more everted, but less flexible. In sagittal plane, limited hindfoot dorsiflexion of ASFF and SFF was compensated for by increased forefoot mobility and a hypermobile hallux. Concerning ankle kinetics, SFF lacked positive joint energy for propulsion while ASFF needed to absorb more negative ankle joint energy during loading response. This may risk fatigue and overuse syndrome of anterior shank muscles in ASFF. Hence, despite a lack of symptoms flatfoot deformity in ASFF affected function. Yet, contrary to what was expected, SFF did not show greater deviations in 3D foot kinematics than ASFF. Symptoms may rather depend on tissue wear and subjective pain thresholds.

Pathological trunk motion during walking in children with amyoplasia: is it caused by muscular weakness or joint contractures?

The aim was to investigate the causes for pathological trunk movements during gait in children with Amyoplasia. Eighteen children with Amyoplasia were compared with 18 typically developed children. Three-dimensional motions of pelvis, thorax and spine during gait were analyzed. Excessive trunk movements were defined as being above 4 standard deviations of those of typically developed children. Clinical examination of active strength and passive range of motion of the hip, knee and ankle joints were correlated to the parameter that showed the greatest prevalence of pathological trunk motion. The greatest prevalence of 56% was seen for thorax obliquity range during walking. The spine angles showed the lowest deviations from typically developed children. Significant correlations (p<0.001) between thorax obliquity range and clinical parameters were found for passive hip extension, hip flexion, hip abduction and active hip extension, hip flexion and ankle dorsiflexion strength. The highest correlation coefficients were found for passive hip flexion and active hip flexion strength of rho=-0.73 and rho=-0.69 respectively. Excessive thorax obliquity during gait in children with Amyoplasia could be mainly caused by reduced strength and mobility of the hip. Therefore both mobility and strength of the hip are equally important and should be increased in the therapy to improve gait in children with Amyoplasia.