Splint: the efficacy of orthotic management in rest to prevent equinus in children with cerebral palsy, a randomised controlled trial

Abstract

Background: Range of motion deficits of the lower extremity occur in about the half of the children with spastic cerebral palsy (CP). Over time, these impairments can cause joint deformities and deviations in the children's gait pattern, leading to limitations in moblity. Preventing a loss of range of motion is important in order to reduce secondary activity limitations and joint deformities. Sustained muscle stretch, imposed by orthotic management in rest, might be an effective method of preventing a decrease in range of motion. However, no controlled study has been performed.

Methods: A single blind randomised controlled trial will be performed in 66 children with spastic CP, divided over three groups with each 22 participants. Two groups will be treated for 1 year with orthoses to prevent a decrease in range of motion in the ankle (either with static or dynamic knee-ankle-foot-orthoses) and a third group will be included as a control group and will receive usual care (physical therapy, manual stretching). Measurements will be performed at baseline and at 3, 6, 9 and 12 months after treatment allocation. The primary outcome measure will be ankle dorsiflexion at full knee extension, measured with a custom designed hand held dynamometer. Secondary outcome measures will be i) ankle and knee flexion during gait and ii) gross motor function. Furthermore, to gain more insight in the working mechanism of the orthotic management in rest, morphological parameters like achilles tendon length, muscle belly length, muscle fascicle length, muscle physiological cross sectional area length and fascicle pennation angle will be measured in a subgroup of 18 participants using a 3D imaging technique.

Discussion: This randomised controlled trial will provide more insight into the efficacy of orthotic management in rest and the working mechanisms behind this treatment. The results of this study could lead to improved treatments.

Trial registration number: Nederlands Trial Register NTR2091.

Figure 1

Schematic overview of the different architectural parameters that determine the length of the muscle tendon complex of the medial Gastrocnemius muscle. Symbols are explained in the text.

Figure 2

Three point's pressure for correction of deformity. (a)The equines correction will be performed by exerting force on the dorsal side of the lower leg (just below the knee), on the instep of the foot and under the ball of the foot. (b)The valgus correction of the calcaneus will be performed by a exerting a force laterally on the heel/calcaneus, laterally on the middle of the lower leg and medially on the lower leg, just above the medial malleolus. (c) The forefoot abduction correction will be performed by exerting a medial stabilization force calcaneus and talus and a lateral force on the calcaneus en the fifth os metatarsi. (d) The varus correction of the calcaneus will be performed by exerting force on the medial part of the calcaneus, medially on the middle of the lower leg and laterally on the lower leg, just above the lateral malleolus. (e)The forefoot adduction will be performed by exerting force on the tuberositas of the fifth os metatarsi, by exerting force laterally on the calcaneus and laterally on the first metatarsal phalangeal joint.

Figure 3

Manual for dynamic splint settings.

Figure 4

Photographic illustration of the hand held dynamometer. The hand held dynamometer consists of an adjustable foot fixation, a torque wrench and a goniometer. The foot fixation has parts supporting the forefoot and calcaneus. These parts are connected by a rod, allowing independent adjustments in rotation and abduction/adduction. The forefoot part is equipped with a fixation point to the table when needed (*).

Figure 5

Ankle-moment plots. This figure will be created from the values measured with the hand held dynamometer. The dotted line will be used to calculate the muscle tendon complex (MTC) stiffness by calculating the slope of that line.

Figure 6

Path of the ultrasound probe during scanning the medial Gastrocnemius muscle (MGM). The probe follows the path over the black line. It starts proximal, with the probe perpendicular to the path. First, the probe will be guided from lateral to medial over the respectively lateral and medial condyle of the femur. Then the probe will be rotated and moved to distal between the medial and lateral border of medial Gastrocnemius muscle belly towards the distal end of the muscle belly, the Gastrocnemus muscle (GM) tendon and the calcaneus.

Figure 7

The orientation of the mid-longitudinal fascicle plane. Three orientation items (*) were used to define the mid-longitudinal fascicle plane of the medial Gastrocnemius muscle (MGM) (shaded plane and inset): 1) The estimate of the origin of the medial Gastrocnemius muscle (at 1/4^th of the line from medial to lateral condyle of the femur, see inset A) 2) the most distal muscle belly end, and 3) a point on the line perpendicular to tangent to the distal aponeurosis in the transversal plane. The direction of the tangent is determined in the distal part of the medial Gastrocnemius muscle belly exactly in between the medial Gastrocnemius muscle borders (see inset B).

Figure 8

Measurement and calculation of muscle geometry of medial Gastrocnemius muscle within its mid-longitudinal fascicle plane. (A) The mid-longitudinal fascicle plane, determined with 3D ultrasound. The medial Gastrocnemius muscle (MGM) is covered by the subcutis (SUB) and supported by Soleus muscle (SM). Parts of both femur (fem) and tibia (tib) are shown. The black dotted lines define the outline of the muscle. The most distal muscle belly end is indicated by a black arrow. The length of the target fascicle (ℓ_(fasc)) (dashed black line), centred at 2/3^rd (*) of muscle belly length (from the origin) is measured. Muscle thickness (ℓ_{(m th)}) was calculated as the distance between the proximal and the distal aponeurosis at the proximal end of the target fascicle (left black double arrow). The fascicle-aponeurosis angle (γ_(fasc)) was calculated as the mean of the angles of the fascicle with the proximal and distal aponeurosis (black arcs). Scale bar depicts 1 cm. (B) Schematic overview of morphological muscle parameters in the mid-longitudinal fascicle plane of the medial Gastrocnemius muscle. The length of the aponeurosis (ℓ_a) and the length of the physiological cross-sectional area (ℓ_Af) will be calculated from this model. The muscle belly length (ℓ_m) will be measured from the origin at the femur condyle to the distal end of the muscle belly. The tendon length (ℓ_t) will be measured from the distal muscle belly end to the insertion at the calcaneus.