Edward A. Millar

Supramalleolar Osteotomy for Ankle Valgus in Myelomeningocele

Fifty-five supramalleolar osteotomies were performed in 35 patients for progressive hindfoot valgus in myelomeningocele. All patients were ambulatory. The most common motor level of innervation was L3 in 42 limbs. The average age at surgery was 12 years. The average follow-up was 8 years. Preoperatively, all patients experienced progressive difficulty with brace use, and anteroposterior weight-bearing ankle radiographs showed a valgus tilt of the talotibial angle (TTA) of > or = 10 degrees with an average of 18 degrees. The average postoperative correction of TTA was 17 degrees. The results were graded as follows: excellent, 42 limbs; good, eight limbs; fair, three limbs; and poor, two limbs. The fair and poor limb results were the result of loss of correction or nonunion. The best results were seen when the TTA was corrected to 5 degrees of varus.

Spinal Cord Implant Studies

A loaded probe technique was used to measure the current density distribution resulting from application of electrical current to the spinal cords of live anesthetized stumptail macaque monkeys and fresh human cadaver spinal cords via the electrode arrays of four commercially available spinal implant systems used for management of intractable pain.

A method for the display of balance platform center of pressure data

Abstract A new method for the display of balance platform center of pressure data is presented. Results obtained through the testing of a normal child and an ambulatory cerebral palsied child are used to demonstrate the technique. Instrumentation requirements for clinical implementation of the procedure are also discussed.

Cerebellar Implant Studies

Electrical currents were applied to the cerebellum of anesthetized monkeys using techniques similar to those employed in human cerebellar electrode implant systems. Alterations in the bloodbrain barrier were not observed. Histological damage, when present, appeared secondary to mechanical injury rather than to application of current. Measurement of current density in the monkey and human cerebellum indicated that with the electrode configuration employed, most of the current is retained in the vicinity of the electrodes. In human patients with spasticity and dyskinesia, application of current through implanted cerebellar electrode units relieves spasticity and also has been associated with reduction of somatosensory evoked potential amplitude. The amount of current required for clinical improvement and for alteration of evoked potential amplitude has remained stable in all patients, even those followed for more than a year. These observations suggest that the methods described do not produce appreciable cerebellar damage.