Eok
One of the most difficult problems in studying foot deformities has been the poor availability of diagnostic testing to classify levels of severity. Traditionally, radiographs have been the main method, however, this provides poor reliability. The use of anterior radiographic tomography has been reported to show poor specificity for the abnormal deformity (1382). The use of the pediobarograph has become much more common in the past ten years and has been demonstrated to be useful in assessing foot deformities (1383). We have evaluated this device for children with cerebral palsy and have found it provides the best assessment and assignment of a magnitude for varus valgus foot position. The technique we use assigns a number, ranging from –60 to +60, with a number between –15 and +15 representing a normal foot. Feet with –40 and over have severe varus, and feet with +40 and over have severe valgus. The numbers in between demonstrate moderate deformities. Although the pediobarograph is useful to assess the magnitude of the varus deformity, it is less helpful to assess the cause. The EMG is the primary tool to assess the cause of the varus deformity; meaning the tibialis anterior and gastrocnemius should be recorded with surface electrodes in the tibialis posterior with a fine wire electrode. These EMGs have to be correlated to the gait cycle using foot switches or kinematics. The EMG activity has to be correlated to the kinematic motion of the ankle joint and the foot progression angle. Also, the physical examination should focus on the range of motion of the subtalar joint and the position of the foot in the foot flat stance. The use of the Coleman block test to separate a fixed cavus forefoot deformity with a supple hindfoot from a fixed hindfoot deformity with forefoot deformity occasionally is helpful (1384). The Coleman block test is most useful in the child who has had a heelcord lengthening and still has varus. Most children with spastic varus have little pressure on the first ray, which demonstrates that the hindfoot varus is not being caused by a fixed forefoot cavovarus; therefore, the Coleman block test has little significance. Eok, a 14-year-old boy with left hemiplegia, who was an independent ambulator in the community, was referred for gait evaluation because of inturning of his left foot. Physical examination on the right was normal, and on the left, the popliteal angle was 47 degrees, extended knee dorsiflexion was minus 7 degrees and flexed knee dorsiflexion was 2 degrees. The left internal rotation of the hip was 65 degrees and external rotation was 21 degrees. Subtalar motion showed forefoot abduction to neutral and hindfoot eversion to 10 degrees. Transmalleolar axis to thigh was 12 degrees internal. The kinematics demonstrated left ankle plantar flexion at foot contact of minus 5 degrees and maximum dorsiflexion very early and only to 10 degrees. No first rocker was noted on the left side but was present on the right side. There was a 42 degrees internal foot progression angle on the left and 7 degrees internal on the right. Image 13-14.2 EMG of the tibialis anterior was appropriately phasic while the tibialis posterior and peroneus brevis had activity throughout stance phase of the gait cycle, except the early stance phase. The hamstrings and rectus were co-contracting in early stance as secondary stabilizers of the knee. Image 13-14.4 Pediobarograph showed decreased heel impulse, minimal heel contact and relatively symmetric pressure in the lateral midfoot and forefoot with normal varus –valgus measure. Image 13-14.3 The rotational profile of the kinematics demonstrated that the right side of the pelvis was forward throughout most of the cycle, and the hip on the left was internally rotated approximately 20 degrees. There was approximately 20 degrees of internal tibial torsion on the left. The foot progression angle (FPA) was internal 40 degrees on the left side. Image 13-14.6 Kinematics showed increased knee flexion at foot contact, coming to full extension in stance, but with late and decreased knee flexion in swing. Ankle dorsiflexion showed no first rocker on the left, and early dorsiflexion in stance. Knee moment showed significant knee flexion moment throughout stance, and the ankle moment on the left had a consistent high plantarflexion moment on the left, while this was much more variable on the right. The left ankle power curve shows high absorption and midstance vault generation pattern. Image 13-14.6 Based on this, the primary cause of the internal rotation foot progression and tripping, which was the child’s main concern, was due to internal tibial torsion and increased femoral anteversion on the left, both of which require correction. The gastrocnemius is overactive causing knee extension moment, decreased heel contact, high early plantar flexion moment, and vaulting indicating a need for gastrocnemius lengthening. Based on the EMG of the tibialis posterior and the peroneus brevis, there does not appear to be a primary varus component of this intoeing.
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