T. O'Brien

Leg length discrepancy — an experimental study of compensatory changes in three dimensions using gait analysis

Patients with leg length discrepancy (LLD) develop compensatory mechanisms, which result in kinematic alterations in the lower limbs and pelvis. We investigated these compensatory mechanisms. Seven normal subjects underwent three-dimensional (3-D) gait analysis using a CODA MPX 30(R) analyser. The subjects were fitted with raises of varying heights to one lower limb and then analysed in static and dynamic modes. Pelvic obliquity was the most common mechanism used to compensate for small degrees of leg length discrepancy up to 2.2 cm, particularly in static standing. With larger degrees of discrepancy, the subjects developed flexion of the knee of the longer leg. Compensatory mechanisms during walking were more complex and included a combination of kinematic changes at the pelvis, knee and ankle. We developed mathematical models for the compensatory mechanisms at all the three levels. We conclude that 3-D gait analysis is a useful tool in the assessment of patients with functional and structural leg length discrepancies.

Factors associated with internal hip rotation gait in patients with cerebral palsy

Abstract: Internal rotation gait is common in children with cerebral palsy. Factors thought to contribute include femoral anteversion, hip flexor tightness, imbalance of hip rotators, and hamstring and adductor tightness. The exact cause of internal rotation must be defined before contemplating surgery. We investigated the prevalence of internal hip rotation and associated factors, which are considered to influence this walking pattern, in patients with cerebral palsy. Gait laboratory data of 222 patients with cerebral palsy were studied retrospectively. Two groups were selected; those with maximum dynamic hip internal rotation of more than 27 degrees and those with less than 20 degrees. Of 222 patients, 27.0% (diplegia, 61.7%; hemiplegia, 38.3%) had at least one hip with dynamic internal rotation of more than 27 degrees. This study suggests that dynamic hip internal rotation is multifactorial in origin. The most significant differences in clinical measures were found in values of passive hip external rotation range, femoral anteversion and hip flexor contracture. We discuss the role of early treatment of hip flexion contracture.

The kinematic patterns of toe-walkers

Children who toe-walk can pose a diagnostic problem. The differential diagnosis includes mild spastic diplegia and idiopathic toe-walking. Clinical differentiation between these two patient groups can be particularly difficult, and there are no objective diagnostic tests to assist the clinician. We assessed 50 children who toe-walk to define the kinematic patterns of lower-limb joint motion in the sagittal plane. There were 23 children with mild spastic diplegia. 22 idiopathic toe-walkers, and five normal children who were asked to toe-walk. We found characteristic patterns of knee and ankle motion that differentiated spastic diplegia from idiopathic toe-walking. Normal children asked to toe-walk had the same pattern as the idiopathic group. Gait analysis is a diagnostic tool that enables the clinician objectively to differentiate mild spastic diplegia from idiopathic toe-walking.

Abnormalities in the uninvolved lower limb in children with spastic hemiplegia: the effect of actual and functional leg-length discrepancy.

We assessed the pattern of gait in children with spastic hemiplegia and a leg-length discrepancy, particularly in relation to the uninvolved limb. The kinematics of the uninvolved limbs were compared with the pattern in normal children. The uninvolved limbs in children with hemiplegia and a significant leg-length discrepancy were compared with the uninvolved limb in those children who did not have a leg-length discrepancy. We found that the involved and uninvolved legs in patients with hemiplegia had characteristic patterns that were significantly different from normal. The kinematics of the involved leg were not affected by the presence of a leg-length discrepancy. The abnormal pattern in the uninvolved limb was more exaggerated in children with a leg-length discrepancy. The abnormal sagittal plane kinematics in the uninvolved lower limb in hemiplegic children appears to be related to the presence of an actual or functional leg-length discrepancy and have not previously been described. Our findings suggest that attention be paid to the functional and actual leg-length discrepancy that exists in these children, and early consideration be given to epiphysiodesis of the uninvolved limb.

Split tibialis posterior tendon transfer in the treatment of spastic equinovarus foot

Sixteen patients with cerebral palsy causing equinovarus deformity were treated surgically. All of these patients underwent preoperative gait analysis by using a CODA-3 motion analyzer. The equinus deformity was assessed by using sagittal kinematics, and in particular, the range of movement of the ankle during stance phase and the maximal dorsiflexion during swing. The varus deformity was assessed by the degree of varus of the foot at prepositioning. The degree of varus was obtained by measuring the angle generated between the plane of progression and a line joining a marker on the heel to a marker on the fifth metatarsal in the transverse plane. All patients underwent split tibialis posterior tendon transfer and, in 13, this was combined with tendo calcaneus lengthening. Clinical assessment and gait analysis repeated 1 year postoperatively confirmed good outcome after split tibialis posterior tendon transfer in combination with gastrocnemius lengthening. This was confirmed by using sagittal kinematic analysis and quantitative assessment of the degree of varus of the foot at the time of prepositioning.

The influence of estimated body segment parameters on predicted joint kinetics during diplegic cerebral palsy gait

Inverse Dynamic calculations are routinely used in joint moment and power estimates during gait with anthropometric data often taken from published sources. Many biomechanical analyses have highlighted the need to obtain subject-specific anthropometric data (e.g. Mass, Centre of Mass, Moments of Inertia) yet the types of imaging techniques required to achieve this are not always available in the clinical setting. Differences in anthropometric sets have been shown to affect the reactive force and moment calculations in normal subjects but the effect on a paediatric diplegic cerebral palsy group has not been investigated. The aim of this study was to investigate the effect of using different anthropometric sets on predicted sagittal plane moments during normal and diplegic cerebral palsy gait. Three published anthropometric sets were applied to the reactive force and moment calculations of 14 Cerebral Palsy and 14 Control subjects. Statistically significant differences were found when comparing the different anthropometric sets but variability in the resulting sagittal plane moment calculations between sets was low (0.01-0.07 Nm/kg). In addition, the GDI-Kinetic, used as an outcome variable to assess whether differences were clinically meaningful, indicated no clinically meaningful difference between sets. The results suggest that the effects of using different anthropometric sets on the kinetic profiles of normal and diplegic cerebral palsy subjects are clinically insignificant.

A pilot study of delayed versus immediate serial casting after botulinum toxin injection for partially reducible spastic equinus.

Background: Serial casting is often prescribed after botulinum toxin injections to improve joint ranges of motion and to potentiate the decrease in hypertonia. The aim of this study was to compare delayed versus immediate serial casting as an adjunct to botulinum toxin therapy for partially reducible spastic equinus. Methods: Twelve children who presented spastic equinus associated with mild gastrosoleus contracture took part. Five of them had a diagnosis of spastic diplegia, whereas 7 had a diagnosis of congenital hemiplegia. Children were randomized to immediate serial casting (same day) or delayed serial casting (4 weeks later) after botulinum toxin injection to their gastrosolei. Casts were replaced weekly for 3 weeks. Results: Three children complained of pain that required recasting in the immediate casting group versus none in the delayed casting group (P = 0.08). At 3 months, there was a 27-degree improvement in the fast dorsiflexion angle (Tardieu R1) in the delayed casting group versus 17 degrees in the immediate casting group (P = 0.029). At 6 months, a 19-degree improvement persisted in the delayed group compared with 11 degrees in the immediate group (P = 0.010). Conclusions: There is a clear benefit in delaying serial casting after the injection of botulinum toxin in the recurrence of spasticity at the gastrosoleus that may also offer an advantage regarding the incidence of painful episodes associated with casting. Most importantly, reducing the recurrence of spasticity by delayed serial casting may offer the possibility of decreasing the frequency of botulinum toxin reinjections. Level of Evidence: Level II.

Use of a dynamic foot pressure index to monitor the effects of treatment for equinus gait in children with cerebral palsy.

The purpose of this study is to introduce and describe a newly developed index using foot pressure analysis to quantify the degree of equinus gait in children with cerebral palsy before and after injection with botulinum toxin. Data were captured preinjection and 12 weeks postinjection. Ten children aged 2½ to 6½ years took part (5 boys and 5 girls). Three of them had a diagnosis of spastic diplegia and 7 of congenital hemiplegia. In total, 13 limbs were analyzed. After orientation and segmentation of raw pedobarographic data, we determined a dynamic foot pressure index graded 0 to 100 that quantified the relative degree of heel and forefoot contact during stance. These data were correlated (Pearson correlation) with clinical measurements of dorsiflexion at the ankle (on a slow and fast stretch) and video observation (using the Observational Gait Scale). Pedobarograph data were strongly correlated with both the Observational Gait Scale scores (R2 = 0.79, P < 0.005) and clinical measurements of dorsiflexion on a fast stretch, which is reflective of spasticity (R2 = 0.70, P < 0.005). We demonstrated the indexs sensitivity in detecting changes in spasticity and good correlation with video observations seems to indicate this techniques potential validity. When manipulated and segmented appropriately, and with the development of a simple ordinal index, we found that foot pressure data provided a useful tool in tracking changes in patients with spastic equinus.

The knee kinematic pattern associated with disruption of the knee extensor mechanism in ambulant patients with diplegic cerebral palsy.

Failure of the knee extensor mechanism is a potentially disastrous complication of diplegic cerebral palsy and if left undiagnosed may lead to a cessation of independent walking. The disruption of the extensor mechanism usually occurs through or distal to the patella. The aim of this article is to describe the knee kinematic pattern associated with such knee pathology. We also present a mathematical model of knee crouch that leads to this problem. In a retrospective review of patients with radiographically proven disruption, we compared the postfailure clinical and kinematic data to premorbid data. All patients included in this study had attended our clinical Gait Analysis Laboratory on two occasions. In the patients with disruption of the extensor mechanism, the kinematic pattern changed from crouch with shock absorption to one of increased crouch and loss of shock absorption. Clinical characteristics included knee flexion contracture and increased hamstring tightness. We demonstrate how the prefailure crouch position of the knee increases the flexor moment arm about the knee. We suggest that this knee crouch position during walking is the primary cause of pathology. Failure of the knee extensor mechanism is associated with a distinctive knee kinematic pattern. Regular gait analysis can help identify this pathology and enable treatment to be planned accordingly. Clin. Anat. 23:586–592, 2010.

The quality assessment of walking in cerebral palsy

Abstract The primary aim of intervention in cerebral palsy is to improve the quality of walking. However, we have no means of measuring this quality or its change following treatment. In this study we set out to develop a quality score for walking which can objectively quantify quality and its change following intervention. We video recorded 60 children while walking, 55 with spastic diplegia and 5 normal children and asked 8 observers to grade the quality of their walking ability using an analogue scale. Having demonstrated the reliability of the scale, each childs quality score was then compared with their sagittal plane kinematic data and their functional data. Balance, speed, range of motion and effort emerged as the key objective and measurable features which determine the quality of walking. These four features were weighted in a formula to equate with the quality scores. The formula was tested using the final 20 patients by comparing their predicted quality scores as derived from the formula with the actual quality scores as determined by the observers.