It is apparent in children with cerebral palsy that beneath the limitations imposed by spastic paralysis there is an ability to voluntarily contract a specific muscle. Procedures in the past, which have taken advantage of this fact, include heel cord lengthening. This lengthening of the gastrocnemius physiological length has diminished the triggering of the stretch reflex and has also decreased the level at which the antagonist muscle—in this case the anterior tibial—is inhibited and voluntary control is blocked by the peripheral stretch reflex.
Femoral shortening also decreases the level at which the stretch reflex is triggered by decreasing the bone length relative to the muscle length. A greater excursion of the joint is now necessary to achieve the same degree of stretch. The eight children reported in this paper were all subjected to femoral shortening in an attempt to achieve for them greater voluntary control of their thigh muscles. In
Ferguson AB. The Effect of Femoral Shortening on Severe Spastic Paraplegia. Arch Surg. 1969;99(3):349-351. doi:10.1001/archsurg.1969.01340150057010