Multi-segment foot kinematics during gait in children with spastic cerebral palsy.

Foot deformities (e.g. planovalgus and cavovarus) are very common in children with spastic cerebral palsy (CP), with the midfoot often being involved. Dynamic foot function can be assessed with 3D gait analysis including a multi-segment foot model. Incorporating a midfoot segment in such a model, allows quantification of separate Chopart and Lisfranc joint kinematics. Yet, midfoot kinematics have not previously been reported in CP. What is the difference in multi-segment kinematics including midfoot joints between common foot deformities in CP and typically-developing feet? 103 feet of 57 children with spastic CP and related conditions were retrospectively included and compared with 15 typically-developing children. All children underwent clinical gait analysis with the Amsterdam Foot Model marker set. Multi-segment foot kinematics were calculated for three strides per foot and averaged. A k-means cluster analysis was performed to identify foot deformity groups that were present within CP data. The deformity type represented by each cluster was based on the foot posture index. Kinematic output of the clusters was compared to typically-developing data for a static standing trial and for the range of motion and kinematic waveforms during walking, using regular and SPM independent t-tests respectively. A neutral, planovalgus and varus cluster were identified. Neutral feet showed mostly similar kinematics as typically-developing data. Planovalgus feet showed increased ankle valgus and Chopart dorsiflexion, eversion and abduction. Varus feet showed increased ankle varus and Chopart inversion and adduction. This study is the first to describe Chopart and Lisfranc joint kinematics in different foot deformities of children with CP. It shows that adding a midfoot segment can provide additional clinical and kinematic information. It highlights joint angles that are more distinctive between deformities, which could be helpful to optimize the use of multi-segment foot kinematics in the clinical decision making process.

Schallig W ，Piening M ，Quirijnen L ，Witbreuk MM ，Buizer AI ，van der Krogt MM ... -  《-》

The effect of mono- versus multi-segment musculoskeletal models of the foot on simulated triceps surae lengths in pathological and healthy gait.

Estimating muscle-tendon complex (MTC) lengths is important for planning of soft tissue surgery and evaluating outcomes, e.g. in children with cerebral palsy (CP). Conventional musculoskeletal models often represent the foot as one rigid segment, called a mono-segment foot model (mono-SFM). However, a multi-segment foot model (multi-SFM) might provide better estimates of triceps surae MTC lengths, especially in patients with foot deformities. What is the effect of a mono- versus a multi-SFM on simulated ankle angles and triceps surae MTC lengths during gait in typically developing subjects and in children with CP with equinus, cavovarus or planovalgus foot deformities? 50 subjects were included, 10 non-affected adults, 10 typically developing children, and 30 children with spastic CP and foot deformities. During walking trials, marker trajectories were collected for two marker models, including a mono- and multi-segment foot; respectively Newington gait model and Oxford foot model. Two musculoskeletal lower body models were constructed in OpenSim with either a mono- or multi-SFM based on the corresponding marker models. Normalized triceps surae MTC lengths (soleus, gastrocnemius medialis and lateralis) and ankle angles were calculated and compared between models using statistical parametric mapping RM-ANOVAs. Root mean square error values between simulated MTC lengths were compared using Wilcoxon signed-rank and rank-sum tests. Mono-SFM simulated significantly more ankle dorsiflexion (7.5 ± 1.2°) and longer triceps surae lengths (difference; soleus:2.6 ± 0.29 %, gastrocnemius medialis:1.7 ± 0.2 %, gastrocnemius lateralis:1.8 ± 0.2%) than a multi-SFM. Differences between models were larger in children with CP compared to typically developing children and larger in the stance compared to the swing phase of gait. Largest differences were found in children with CP presenting with planovalgus (4.8 %) or cavovarus (3.8 %) foot deformities. It is advisable to use a multi-SFM in musculoskeletal models when simulating triceps surae MTC lengths, especially in individuals with planovalgus or cavovarus foot deformities.

Zandbergen MA ，Schallig W ，Stebbins JA ，Harlaar J ，van der Krogt MM ... -  《-》

Kinematics and kinetics of normal and planovalgus feet during walking.

Planovalgus deformity is prevalent in cerebral palsy patients, but very few studies have quantitatively reported differences between planovalgus and normal foot function. Intersegmental foot kinetics have not been reported in this population. In this study, a three segment (hindfoot, forefoot, hallux) kinematic and kinetic model was applied to typically developing (n=10 subjects, 20 feet) and planovalgus (n=10 subjects, 18 feet) pediatric subjects by two clinicians for each subject. Intra-clinician and inter-clinician repeatability of kinematic variables have been previously reported. Variability of kinetic outcomes (joint moments and power) is reported and found to be equally repeatable in typically developing and planovalgus groups. Kinematic differences in the planovalgus foot including excessive ankle eversion (valgus) and plantarflexion, reduced ankle flexion range of motion, and increased midfoot joint dorsiflexion and pronation reflected the reported pathology. Contrary to clinical expectations no significant difference was observed in midfoot flexion or ankle eversion ranges of motion. Kinetic differences in planovalgus feet compared to typically developing feet included reduced ankle plantarflexion moment, ankle power and midfoot joint power.

Saraswat P ，MacWilliams BA ，Davis RB ，D'Astous JL ... -  《-》

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.

Maurer JD ，Ward V ，Mayson TA ，Davies KR ，Alvarez CM ，Beauchamp RD ，Black AH ... -  《-》

Crouch gait changes after planovalgus foot deformity correction in ambulatory children with cerebral palsy.

Ambulatory children with cerebral palsy (CP) may present with several gait patterns due to muscular spasticity, commonly with crouch gait. Several factors may contribute to continuous knee flexion during gait, including hamstring and gastrocnemius contracture. In planovalgus foot deformity, the combination of heel equinus, talonavicular joint dislocation, midfoot break and external tibial torsion also contribute to crouch gait as part of lever arm dysfunction. In this retrospective cohort study, we assessed 21 children with CP (34 feet) who underwent planovalgus foot correction as a single level surgery. Fifteen feet underwent subtalar fusion and 19 feet had lateral calcaneal lengthening. Patients who underwent knee, hip or pelvis surgeries were excluded from the study. The aim was to examine the changes in gait pattern and the correlation between the changes of knee flexion at stance phase with the other kinematic and kinetic parameters after foot surgery. Post surgery change of Maximum knee extension at stance (MKE-dif) was the outcome of interest. The magnitude of change in MKE after surgery increased (less crouch after surgery) in patients who had milder preoperative planovalgus feet and higher preoperative ankle maximum dorsiflexion at stance and ankle power. The gain of knee extension after surgery correlated with correction of ankle hyperdorsiflexion and with increase of knee extension at initial contact and knee power. Patients with high preoperative ankle maximum dorsiflexion may benefit from surgical foot deformity correction to achieve decreased ankle dorsiflexion with no knee surgical intervention.

Kadhim M ，Miller F 《-》