The influence of hip abductor weakness on frontal plane motion of the trunk and pelvis in patients with cerebral palsy.

Trendelenburg walking pattern is a common finding in various disorders, including cerebral palsy (CP), where it is seen in children and adults. Clinically, this deviation is viewed as a consequence of hip abductor weakness resulting in pelvic obliquity. Trunk lean to the ipsilateral side is a common compensatory mechanism to counteract pelvic obliquity and to maintain gait stability. However, no published investigations objectively address pelvic and trunk motions in the frontal plane or examine the correlation with hip abductor weakness in patients with CP. We selected 375 ambulatory (GMFCS I-III) patients with spastic bilateral CP and 24 healthy controls from our gait laboratory database. They had all undergone a standardized three-dimensional analysis of gait, including trunk motion, and a clinical examination including hip abductor strength testing. Selected frontal plane kinematic and kinetic parameters were investigated and statistically tested for correlation (Spearman rank) with hip abductor strength. Only a weak (r=0.278) yet highly significant correlation between trunk lean and hip abductor strength was found. Hip abductor weakness was accompanied by decreased hip abduction moment. However, no significant differences in pelvic position were found between the different strength groups, indicating that the pelvis remained stable regardless of the patients' strength. Our findings indicate that weak hip abductors in patients with CP are accompanied by increased trunk lean to the ipsilateral side while pelvic position is preserved by this compensatory mechanism. However, since this correlation is weak, other factors influencing lateral trunk lean should be considered. In patients with severe weakness of the hip abductors compensatory trunk lean is no longer fully able to stabilize the pelvis, and frontal pelvic kinematics differs from normal during loading response. The results indicate that the stable pelvic position seems to be of greater importance than trunk position for patients with CP. Further studies are needed to investigate other factors influencing lateral trunk lean.

Krautwurst BK ，Wolf SI ，Heitzmann DW ，Gantz S ，Braatz F ，Dreher T ... -  《-》

Which functional impairments are the main contributors to pelvic anterior tilt during gait in individuals with cerebral palsy?

While past investigations focused on describing pelvic motion patterns in the frontal and transversal plane, the sagittal plane "double bump" pattern commonly found in children with cerebral palsy was only rarely investigated, especially concerning the underlying pathology. 375 ambulatory (GMFCS I-III) patients with bilateral spastic cerebral palsy were included in this study. Gait and clinical data (ROM, strength, spasticity) were classified in two different ways: (a) into two groups of normal and enhanced mean anterior pelvic tilt and (b) into two groups of moderate and excessive ROM in pelvic tilt. The results reveal that increased mean pelvic tilt is mainly associated with gait features of reduced hip extension and increased pelvic and trunk obliquity ROM but with increased knee ROM. In the clinical exam this corresponds to a smaller passive knee extension deficit and reduced knee flexor strength. It seems that flexors to extensors strength imbalance at the knee is a major feature why mean pelvic position is tilted anterior whereas maximum passive hip extension is of minor importance. Contrarily, excessive sagittal pelvic ROM is associated with increased knee flexion at initial contact and reduced knee ROM. Furthermore, Duncan-Ely- and Tardieu-tests show both increased values in this group with excessive pelvic range of motion indicating for spastic rectus femoris activation. The results of our study indicate that the two gait variables are influenced by different specific mechanisms which are now described for the first time. Since the pelvis plays a central role during gait, these findings should be considered when planning single event multilevel surgery in patients with cerebral palsy.

Wolf SI ，Mikut R ，Kranzl A ，Dreher T ... -  《-》

The effect of contralateral pelvic drop and trunk lean on frontal plane knee biomechanics during single limb standing.

Pelvic drop as a result of hip abductor weakness has been hypothesized as a potential modifier of frontal plane knee joint kinetics during gait in individuals with pathology such as knee osteoarthritis (OA). However, hip muscle strengthening interventions have failed to find significant reductions in frontal plane loading measures such as the external knee adduction moment (KAM) with altered hip strength. Since this could in part be due to a lack of change in pelvic kinematics between conditions or test sessions or due to alterations in lateral trunk lean angle, the relationship between pelvic drop and subsequent changes in centre of mass with knee joint loading remains unclear. The purpose of this study was to examine the effect of a consciously altered frontal plane centre of mass position (pelvic drop and trunk lean to the contralateral side) on the KAM during single limb standing. Twenty healthy individuals performed a series of single limb standing trials, where they were asked to balance on their dominant leg. KAM was assessed during single limb stance in two conditions: with pelvis and trunk maintained in a level position, and with contralateral pelvic drop. A third condition involving contralateral pelvic drop and trunk lean was assessed to examine exaggerated changes in centre of mass. The KAM increased significantly with contralateral pelvic drop (p=0.001) and with combined contralateral pelvic drop and trunk lean (p<0.001) compared to the level pelvis trials. These findings suggest that pelvic drop alone can significantly increase KAM magnitude, a risk factor for the progression of knee OA. Assessment of pelvic obliquity prior to treatment may allow those with marked pelvic drop to be targeted for hip muscle strengthening.

Takacs J ，Hunt MA 《-》

A prospective functional outcome and motion analysis evaluation of the hip abductors after femur fracture and antegrade nailing.

Archdeacon M ，Ford KR ，Wyrick J ，Paterno MV ，Hampton S ，Ludwig MB ，Hewett TE ... -  《JOURNAL OF ORTHOPAEDIC TRAUMA》

Gait analysis before or after varus osteotomy of the femur for hip osteoarthritis.

Watanabe H ，Shimada Y ，Sato K ，Tsutsumi Y ，Sato M ... -  《BIO-MEDICAL MATERIALS AND ENGINEERING》