The Journal of Bone and Joint Surgery, Vol 60, Issue 7 882-894, Copyright © 1978 by Journal of Bone and Joint Surgery, Inc
Genu recurvatum in spastic cerebral palsy. Report on findings by gait analysis
SR Simon, SD Deutsch, RM Nuzzo, MJ Mansour, JL Jackson, M Koskinen and RK Rosenthal
Using high-speed motion pictures, electromyography, a dynamic piezoelectric
force plate, and computer analysis of the data, the gait patterns of
fifteen children, four to sixteen years old, with spastic cerebral palsy
and genu recurvatum were analyzed to determine the mechanisms producing
genu recurvatum and the effect of fixed-ankle below-the-knee orthoses. In
all children the recurvatum during stance phase began when the tibia
stopped moving forward and disappeared when tibial movement resumed. In six
patients (Group I), excessive activity of the calf muscles in response to
the increasing dorsiflexion moment about the ankle produced by the
foot-floor reaction force arrested the forward motion of the tibia. In six
others (Group II), the contraction of the calf muscles was not sufficiently
strong to resist the dorsiflexion moment and the tibia moved forward until
maximum dorsiflexion had occurred and then stopped. In both instances
recurvatum was produced when the femur continued to move forward over the
stationary tibia and an extension moment was produced at the knee. In no
patient did activity of the knee flexors prevent recurvatum, which was
eliminated only by resumption of forward movement of the tibia. This
movement of the tibia was produced either by heel-off (Group I) or by
sudden unweighting of the limb due to opposite heel-strike (Group II). In
Group I, when tibial motion stopped in the first half of stance phase the
position of the hip rapidly changed from flexion to extension and there was
forward leaning of the trunk, while in Group II the change from hip flexion
to extension occurred with backward leaning of the trunk. The fixed-ankle
below-the-knee orthosis, by preventing excessive dorsiflexion and plantar
flexion, produced more normal moments about all joints, especially the
knee. In the three children (Group III) whose recurvatum was permanently
corrected by the brace, no explanation for the improvement was evident in
these studies.