INCREASING LORDOSIS OF THE OCCIPITOCERVICAL JUNCTION AFTER ARTHRODESIS IN YOUNG-CHILDREN - THE OCCIPITOCERVICAL CRANKSHAFT PHENOMENON

Five children were treated before age 6 years with occipitocervical fu sion for occipitocervical instability. Long-term (average, 11.8 years; range, 8.4-14.5 years) follow-up revealed increasing lordosis across the fused segment in four of the patients, a finding we here refer to as the occipitocervical crankshaft phenomenon. On average, occipitocer vical lordosis increased 1.06 degrees per level fused per year until s keletal maturity. Although such a progression might be expected, to ou r knowledge this is the first report of its occurrence. Compensatory s ubaxial motion was able to overcome this increase in all of the patien ts. We recommend occipitocervical fusion in a neutral or slightly flex ed position in the very young child to account for this predictable in crease in lordosis.