Dislocation of the Hip in Myelodysplasia
THE orthopedic surgeon has a distinct responsibility together with the pediatrician, the neurosurgeon, and the urologist, in the care of children with myelodysplasia. Although little information has been published in regard to orthopedic manifestations of this entity, considerable improvement has been made in recent years in the management and rehabilitation of these children.
The extent of monoplegia or paraplegia varies from one patient to the next. There may be partial sparing of nerve fibers, allowing some innervation distal to the lesion, or there may be total paralysis beyond the level of the lesion. Close observation of these patients over some years may disclose that increased innervation has occurred. This improvement I interpret to be the result of increasing maturity of the spinal cord.
In the patient with flail lower extremities it is not uncommon to find bilateral dislocation of the hips as an acquired phenomenon. The mechanism of the dislocation is not fully understood, although two factors undoubtedly are contributory. One is the tendency for the child with this disorder to keep the feet together, thus adducting both hips; because of paralysis, this constant positioning is unopposed by any abduction, which is the position of greatest stability for the hip. The other factor in production of hip dislocation frequently present in this situation is an active iliopsoas muscle, which is innervated from the second, third, and fourth lumbar nerve roots. Since the iliopsoas muscle inserts into the lesser trochanter, it exerts an anterior pull on the head and neck of . . .