Faculty Bibliography

The process of bone lengthening by cortical fracture and gradual distraction of callus has become well established in the enchondral bones of the extremities. In this study the principles of bone lengthening were applied to the membranous bone of the craniofacial skeleton using the growing dog mandible as a model. Six mongrel dogs five months of age were studied. A unilateral, periosteal-preserving angular corticotomy was performed, and an external minilengthening device was fixed to the mandible perpendicular to the corticotomy. After 10 days of external fixation, the mandible was lengthened 1 mm/day for 20 days and then held in external fixation for 56 days (8 weeks) after which all dogs were killed. Anthropometric measurements and histological analysis of the specimens confirmed that bone lengthening had occurred and that new cortical bone was formed in the expanded areas

An increasingly recognized although small percentage of patients with primary hyperparathyroidism have enlargement of two parathyroid glands. We have treated nine patients with primary hyperparathyroidism associated with such double parathyroid gland enlargement. In four of these patients, marked asymmetry of the two enlarged glands was noted and the failure to recognize and excise a second enlarged parathyroid gland resulted in persistent or recurrent hyperparathyroidism. In one of these patients, the second enlargement was present in a super-numerary mediastinal gland. The subsequent excision of the second enlarged parathyroid gland resulted in normocalcemia in each instance. This contrasts with five patients in whom initial excision of two enlarged glands resulted in normocalcemia with no recurrence of hypercalcemia. Only three patients fulfilled the histologic criteria of true double adenomas. The remainder showed multiglandular hypercellularity. This experience supports identifying all parathyroid glands and recognizing that even minimal enlargement of a gland may be important pathophysiologically, regardless of its histopathologic classification. Excision of both enlarged glands, even if asymmetric, is appropriate