The Effects of the Rectus Femoris Muscle on Knee and Foot Kinematics during the Swing Phase of Normal Walking

The role of rectus femoris (RF) muscle during walking was analyzed through musculoskeletal models to understand the effects of muscle weakness and hyperactivity. Such understanding is fundamental when dealing with pathological gait, but the contribution of RF as a bi-articular muscle is particularly difficult to estimate. Anybody software was used for inverse dynamics computation, and SimWise-4D for forward dynamics simulations. RF force was changed in the range of 0 to 150%, and the resulting kinematics were analyzed. Inverse dynamics showed a short positive RF power in correspondence with the onset of knee extension in the swing phase. Forward dynamics simulations showed an increasing knee flexion and initial toe contact when the RF force was decreased, and increasing knee extension and difficult foot clearance when the RF force was increased. The step became shorter with both increased and reduced RF force. In conclusion, the RF actively contributes to the knee extension in the swing phase. RF also contributes to obtaining a proper step length and to preparing the foot for initial heel contact. So the effect of RF muscle as a bi-articular muscle seems fundamental in controlling the motion of distal segments. RF overactivity should be considered as a possible cause for poor foot clearance in some clinical cases, while RF weakness should be considered in cases with apparent equinus

The Non-Affected Muscle Volume Compensates for the Partial Loss of Strength after Injection of Botulinum Toxin A

Local botulinum toxin (BTX-A, Botox®) injection in overactive muscles is a standard treatment in patients with cerebral palsy. The effect is markedly reduced in children above the age of 6 to 7. One possible reason for this is the muscle volume affected by the drug. Nine patients (aged 11.5; 8.7–14.5 years) with cerebral palsy GMFCS I were treated with BTX-A for equinus gait at the gastrocnemii and soleus muscles. BTX-A was administered at one or two injection sites per muscle belly and with a maximum of 50 U per injection site. Physical examination, instrumented gait analysis, and musculoskeletal modelling were used to assess standard muscle parameters, kinematics, and kinetics during gait. Magnetic resonance imaging (MRI) was used to detect the affected muscle volume. All the measurements were carried out pre-, 6 weeks post-, and 12 weeks post-BTX-A. Between 9 and 15% of the muscle volume was affected by BTX-A. There was no effect on gait kinematics and kinetics after BTX-A injection, indicating that the overall kinetic demand placed on the plantar flexor muscles remained unchanged. BTX-A is an effective drug for inducing muscle weakness. However, in our patient cohort, the volume of the affected muscle section was limited, and the remaining non-affected parts were able to compensate for the weakened part of the muscle by taking over the kinetic demands associated with gait, thus not enabling a net functional effect in older children. We recommend distributing the drug over the whole muscle belly through multiple injection sites

Erratum to: Poor outcome at 7.5years after Stanisavljevic quadriceps transposition for patello-femoral instability

Introduction: Congenital dislocation of the patella and recurrent symptomatic dislocation in adolescents are difficult pathologies to treat. Stanisavljevic described an extensive release procedure essentially involving medializing the entire lateral quadriceps and medial soft tissue stabilization. There are no significant series reporting the success of this method. This procedure has been performed in our institution over several years and we report our results. Method: Retrospective case series. Between 1990 and 2007, 20 knees in 13 children and adolescents (mean age 12.8years; 4-17, 7 female) with recurrent or congenital dislocation of the patella (8 knees) underwent this procedure after failed conservative treatment (mean follow-up 7.5years; 4-16). All were immobilized in a long leg cast for 6weeks. Results: Five knees in five patients (20%, 1 congenital dislocation) reported their knees as improved without further dislocations. Out of the 15 knees with failures (80%) 12 in six patients (60%) were revised due to redislocation. Three knees in two patients (15%) still had dislocations or subluxations, but any revision was refused. Three knees in three patients caused pain and discomfort during daily activity. Redislocation first developed after a mean of 21.3months (4-72) postoperatively. Only one patient had returned to sport at the 12-month follow-up. Discussion: The Stanisavljevic procedure produces a mediocre success rate with our long-term follow-up series showing a failure rate up to 80%. We therefore recommend more specific procedures dealing with the anatomical deformity such as trochleaplasty to produce superior success rates

Can developmental trajectories in gait variability provide prognostic clues in motor adaptation among children with mild cerebral palsy? A retrospective observational cohort study

AimTo investigate whether multiple domains of gait variability change during motor maturation and if this change over time could differentiate children with a typical development (TDC) from those with cerebral palsy (CwCP).MethodsThis cross-sectional retrospective study included 42 TDC and 129 CwCP, of which 99 and 30 exhibited GMFCS level I and II, respectively. Participants underwent barefoot 3D gait analysis. Age and parameters of gait variability (coefficient of variation of stride-time, stride length, single limb support time, walking speed, and cadence; as well as meanSD for hip flexion, knee flexion, and ankle dorsiflexion) were used to fit linear models, where the slope of the models could differ between groups to test the hypotheses.ResultsMotor-developmental trajectories of gait variability were able to distinguish between TDC and CwCP for all parameters, except the variability of joint angles. CwCP with GMFCS II also showed significantly higher levels of gait variability compared to those with GMFCS I, these levels were maintained across different ages.InterpretationThis study showed the potential of gait variability to identify and detect the motor characteristics of high functioning CwCP. In future, such trajectories could provide functional biomarkers for identifying children with mild movement related disorders and support the management of expectations

Restoration of Heel–Toe Gait Patterns for the Prevention of Asymmetrical Hip Internal Rotation in Patients with Unilateral Spastic Cerebral Palsy

Forward modelling has indicated hip internal rotation as a secondary physical effect to plantar flexion under load. It could therefore be of interest to focus the treatment for patients with unilateral spastic cerebral palsy on achieving a heel–toe gait pattern, to prevent development of asymmetrical hip internal rotation. The aim of this preliminary retrospective cohort investigation was to evaluate the effect of restoring heel–toe gait, through use of functional orthoses, on passive hip internal rotation. In this study, the affected foot was kept in an anatomically correct position, aligned to the leg and the gait direction. In case of gastrosoleus shortness, a heel raise was attached to compensate for the equinus and yet to provide heel–floor contact (mean equinus = −2.6 degrees of dorsiflexion). Differences in passive hip internal rotation between the two sides were clinically assessed while the hip was extended. Two groups were formed according to the achieved correction of their gait patterns through orthotic care: patients with a heel-toe gait (with anterograde rocking) who wore the orthosis typically for at least eight hours per day for at least a year, or patients with toe-walking (with retrograde rocking) in spite of wearing the orthosis who used the orthosis less in most cases. A Student’s t-test was used to compare the values of clinically assessed passive hip rotation (p < 0.05) between the groups and the effect size (Hedges’ g) was estimated. Of the 70 study participants, 56 (mean age 11.5 y, majority GMFCS 1, similar severity of pathology) achieved a heel-toe gait, while 14 remained as toe-walkers. While patients with heel–toe gait patterns showed an almost symmetrical passive hip internal rotation (difference +1.5 degrees, standard deviation 9.6 degrees), patients who kept toe-walking had an increased asymmetrical passive hip internal rotation (difference +10.4 degrees, standard deviation 7.5 degrees; p = 0.001, Hedges’s g = 0.931). Our clinical findings are in line with the indications from forward modelling that treating the biomechanical problem might prevent development of a secondary deformity. Further prospective studies are needed to verify the presented hypothesis

The pediatric LCP hip plate for fixation of proximal femoral osteotomy in cerebral palsy and severe osteoporosis

Hip dislocation or subluxation together with poor nutrition, reduced weight bearing, and osteoporosis is a frequent condition in severe cerebral palsy (CP). Severe osteoporosis may cause difficulties in fixing a proximal femoral osteotomy with a conventional blade plate. The Pediatric locking compression plate (LCP) Hip Plate system offers better grip and more stable fixation

The association between premature plantarflexor muscle activity, muscle strength, and equinus gait in patients with various pathologies

This study provides an overview on the association between premature plantarflexor muscle activity (PPF), muscle strength, and equinus gait in patients with various pathologies. The purpose was to evaluate whether muscular weakness and biomechanical alterations are aetiological factors for PPF during walking, independent of the underlying pathology. In a retrospective design, 716 patients from our clinical database with 46 different pathologies (orthopaedic and neurologic) were evaluated. Gait analysis data of the patients included kinematics, kinetics, electromyographic activity (EMG) data, and manual muscle strength testing. All patients were clustered three times. First, patients were grouped according to their primary pathology. Second, all patients were again clustered, this time according to their impaired joints. Third, groups of patients with normal EMG or PPF, and equinus or normal foot contact were formed to evaluate the association between PPF and equinus gait. The patient groups derived by the first two cluster methods were further subdivided into patients with normal or reduced muscle strength. Additionally, the phi correlation coefficient was calculated between PPF and equinus gait. Independent of the clustering, PPF was present in all patient groups. Weak patients revealed PPF more frequently. The correlations of PPF and equinus gait were lower than expected, due to patients with normal EMG during loading response and equinus. These patients, however, showed higher gastrocnemius activity prior to foot strike together with lower peak tibialis anterior muscle activity in loading response. Patients with PPF and a normal foot contact possibly apply the plantarflexion-knee extension couple during loading response. While increased gastrocnemius activity around foot strike seems essential for equinus gait, premature gastrocnemius activity does not necessarily produce an equinus gait. We conclude that premature gastrocnemius activity is strongly associated with muscle weakness. It helps to control the knee joint under load independent from the underlying disease, and it is therefore a secondary deviation. If treated as primary target, caution should be exercised