Symptomatic flatfoot in cerebral palsy.

Purpose Of Review: The purpose of this review is to evaluate the current literature and best practices in the evaluation and treatment of symptomatic flatfoot in cerebral palsy.

Recent Findings: While techniques to reconstruct the neuromuscular flatfoot and reestablish bony levers have remained similar over time, the concept of surgical dosing has helped guide appropriate interventions based on the magnitude of disease and functional level of the child. Moreover, the utilization of multisegment foot modeling in motion analysis has allowed quantitative description of such deformities and their impact on gait.

How does patellar tendon advancement alter the knee extensor mechanism in children treated for crouch gait?

Background: The patellar tendon advancement (PTA) procedure, often coupled with a distal femoral extension osteotomy (DFEO), is increasingly used to treat persistent crouch gait. In this study, we investigated relationships between patella position, knee flexion, and the patellar tendon moment arm in children treated with the DFEO and PTA procedures.

Methods: We retrospectively analyzed pre- and post-operative radiographs and gait metrics from 63 knees that underwent DFEO and PTA procedures at Gillette Children's Specialty Healthcare.

The coupled effects of crouch gait and patella alta on tibiofemoral and patellofemoral cartilage loading in children.

Background: Elevated tibiofemoral and patellofemoral loading in children who exhibit crouch gait may contribute to skeletal deformities, pain, and cessation of walking ability. Surgical procedures used to treat crouch frequently correct knee extensor insufficiency by advancing the patella. However, there is little quantitative understanding of how the magnitudes of crouch and patellofemoral correction affect cartilage loading in gait.

Influence of patellar position on the knee extensor mechanism in normal and crouched walking.

Patella alta is common in cerebral palsy, especially in patients with crouch gait. Correction of patella alta has been advocated in the treatment of crouch, however the appropriate degree of correction and the implications for knee extensor function remain unclear. Therefore, the goal of this study was to assess the impact of patellar position on quadriceps and patellar tendon forces during normal and crouch gait.

Radiographic and Respiratory Effects of Growing Rods in Children With Spinal Muscular Atrophy.

Background: Respiratory weakness and spinal deformity are common in patients with spinal muscular atrophy (SMA). Posterior (distraction type) growing rods have recently gained favor as a treatment option in this population, due to their ability to prevent spinal deformity progression and their potential to allow lung volumes to increase over time. The objective of this study was to determine the impact of posterior growing rods on the spinal alignment and respiratory function in children with SMA with intermediate term follow-up.

To Cast, to Saw, and Not to Injure: Can Safety Strips Decrease Cast Saw Injuries?

Background: Placement and removal of fiberglass casts are among the more-common interventions performed in pediatric orthopaedic surgery offices. However, cast removal is associated with abrasive injuries and burns from the oscillating cast saw, and these injuries can occur even when the cast is removed by experienced personnel. It is unknown whether an added barrier, such as a safety strip, can mitigate injuries from blade-to-skin contact during cast removal with the oscillating saw.

The Influence of Component Alignment and Ligament Properties on Tibiofemoral Contact Forces in Total Knee Replacement.

The study objective was to investigate the influence of coronal plane alignment and ligament properties on total knee replacement (TKR) contact loads during walking. We created a subject-specific knee model of an 83-year-old male who had an instrumented TKR. The knee model was incorporated into a lower extremity musculoskeletal model and included deformable contact, ligamentous structures, and six degrees-of-freedom (DOF) tibiofemoral and patellofemoral joints.

Influence of Ligament Properties on Tibiofemoral Mechanics in Walking.

Computational knee models provide a powerful platform to investigate the effects of injury and surgery on functional knee behavior. The objective of this study was to use a multibody knee model to investigate the influence of ligament properties on tibiofemoral kinematics and cartilage contact pressures in the stance phase of walking. The knee model included 14 ligament bundles and articular cartilage contact acting across the tibiofemoral and patellofemoral joints.

Influence of step rate and quadriceps load distribution on patellofemoral cartilage contact pressures during running.

Interventions used to treat patellofemoral pain in runners are often designed to alter patellofemoral mechanics. This study used a computational model to investigate the influence of two interventions, step rate manipulation and quadriceps strengthening, on patellofemoral contact pressures during running. Running mechanics were analyzed using a lower extremity musculoskeletal model that included a knee with six degree-of-freedom tibiofemoral and patellofemoral joints.

Prediction and Validation of Load-Dependent Behavior of the Tibiofemoral and Patellofemoral Joints During Movement.

The study objective was to construct and validate a subject-specific knee model that can simulate full six degree of freedom tibiofemoral and patellofemoral joint behavior in the context of full body movement. Segmented MR images were used to reconstruct the geometry of 14 ligament bundles and articular cartilage surfaces. The knee was incorporated into a lower extremity musculoskeletal model, which was then used to simulate laxity tests, passive knee flexion, active knee flexion, and human walking.

Ability of sagittal kinematic variables to estimate ground reaction forces and joint kinetics in running.

Study Design: Controlled laboratory study, cross-sectional design.

Objective: To determine if sagittal kinematic variables can be used to estimate select running kinetics.

Background: Excessive loading during running has been implicated in a variety of injuries, yet this information is typically not assessed during a standard clinical examination.

Empirical evaluation of gastrocnemius and soleus function during walking.

Distinguishing gastrocnemius and soleus muscle function is relevant for treating gait disorders in which abnormal plantarflexor activity may contribute to pathological movement patterns. Our objective was to use experimental and computational analysis to determine the influence of gastrocnemius and soleus activity on lower limb movement, and determine if anatomical variability of the gastrocnemius affected its function. Our hypothesis was that these muscles exhibit distinct functions, with the gastrocnemius inducing limb flexion and the soleus inducing limb extension.

Sensor-based assessment of cast placement and removal.

Appropriate pressure during the application of a cast is critical to provide adequate stabilization of fractures. Force-sensing resistors (FSR) were used to measure pressure during cast placement and removal. The data demonstrated a signature pattern of skin pressure during the different steps of cast placement and removal.

Increasing running step rate reduces patellofemoral joint forces.

Purpose: Increasing step rate has been shown to elicit changes in joint kinematics and kinetics during running, and it has been suggested as a possible rehabilitation strategy for runners with patellofemoral pain. The purpose of this study was to determine how altering step rate affects internal muscle forces and patellofemoral joint loads, and then to determine what kinematic and kinetic factors best predict changes in joint loading.

Methods: We recorded whole body kinematics of 30 healthy adults running on an instrumented treadmill at three step rate conditions (90%, 100%, and 110% of preferred step rate).

The modulation of forward propulsion, vertical support, and center of pressure by the plantarflexors during human walking.

The gastrocnemius and soleus both contribute to the ankle plantarflexor moment during the mid- and terminal stance phases of gait. The gastrocnemius also generates a knee flexion moment that may lead to dynamic function that is unique from the soleus. This study used a muscle stimulation protocol to experimentally compare the contributions of individual plantarflexors to vertical support, forward propulsion and center of pressure (CoP) movement during normal gait.

Empirical assessment of dynamic hamstring function during human walking.

The hamstrings are often associated with the development of crouch gait, a fatiguing form of walking characterized by excessive hip flexion, knee flexion and ankle dorsiflexion during stance. However, recent studies have called into question whether abnormally active hamstrings induce the limb to move into a crouch posture. The purpose of this study was to directly measure the influence of the hamstrings on limb posture during stance.