Tibiofemoral Contact Measures During Standing in Toe-In and Toe-Out Postures.

Knee osteoarthritis is thought to result, in part, from excessive and unbalanced joint loading. Toe-in and toe-out gait modifications produce alterations in external knee joint moments, and some improvements in pain over the short- and long-term. The aim of this study was to probe mechanisms of altered joint loading through the assessment of tibiofemoral contact in standing with toe-in and toe-out positions using an open magnetic resonance scanner. In this study, 15 young, healthy participants underwent standing magnetic resonance imaging of one of their knees in 3 foot positions. Images were analyzed to determine contact in the tibiofemoral joint, with primary outcomes including centroid of contact and contact area for each compartment and overall. The centroid of contact shifted laterally in the lateral compartment with both toe-in and toe-out postures, compared with the neutral position (P < .01), while contact area in the medial and lateral compartments showed no statistical differences. Findings from this study indicate that changes in the loading anatomy are present in the tibiofemoral joint with toe-in and toe-out and that a small amount of lateralization of contact, especially in the lateral compartment, does occur with these altered lower limb orientations.

Classification of midfoot break using multi-segment foot kinematics and pedobarography.

Midfoot break (MFB) is a foot deformity that can occur when ankle dorsiflexion is restricted due to muscle spasticity or contractures, causing abnormal increased motion through the midfoot. MFB has been previously described in terms of forefoot (FF) and hindfoot (HF) motion in the sagittal plane. The purpose of this study was to further classify MFB by describing FF and HF motion in the coronal and transverse planes along with plantar pressures, with the goal of optimizing treatment of this deformity. Three-dimensional foot kinematics were assessed using a multi-segment foot model in children with MFB (n=30) and children with no foot or gait abnormalities (n=30). The MFB group was subdivided into three categories: (1) Pronated MFB, (2) Supinated MFB and (3) Flat Foot MFB. Unique patterns of plantar pressures and foot kinematics were identified for each MFB group. The Pronated MFB group had increased medial midfoot pressures, increased forefoot pronation, and increased external forefoot rotation (forefoot abductus). The Supinated MFB group had increased lateral midfoot pressures, increased forefoot supination, and increased internal forefoot rotation (forefoot adductus). In the Flat Foot MFB group, midfoot pressures were increased and distributed uniformly between the medial and lateral sides, forefoot pronation was increased, and internal forefoot rotation was present. By combining this new information with previously reported methods of measuring sagittal plane kinematics of MFB, it is now possible to characterize midfoot break in terms of severity and foot-floor contact pattern.

A kinematic description of dynamic midfoot break in children using a multi-segment foot model.

Midfoot break (MFB) is a foot deformity that occurs most commonly in children with cerebral palsy (CP), but may also affect children with other developmental disorders. Dynamic MFB develops because the muscles that cross the ankle joint are hypertonic, resulting in a breakdown and dysfunction of the bones within the foot. In turn, this creates excessive motion at the midfoot. With the resulting inefficient lever arm, the foot is then unable to push off the ground effectively, resulting in an inadequate and painful gait pattern. Currently, there is no standard quantitative method for detecting early stages of MFB, which would allow early intervention before further breakdown occurs. The first step in developing an objective tool for early MFB diagnosis is to examine the difference in dynamic function between a foot with MFB and a typical foot. Therefore, the main purpose of this study was to compare the differences in foot motion between children with MFB and children with typical feet (Controls) using a multi-segment kinematic foot model. We found that children with MFB had a significant decrease in peak ankle dorsiflexion compared to Controls (1.3 ± 6.4° versus 8.6 ± 3.4°) and a significant increase in peak midfoot dorsiflexion compared to Controls (15.2 ± 4.9° versus 6.4 ± 1.9°). This study may help clinicians track the progression of MFB and help standardize treatment recommendations for children with this type of foot deformity.