Since the presentation of this paper we have used the halo traction apparatus on an additional thirty-one patients with high thoracic or collapsing scoliosis. This has provided a marked improvement in both positioning and immobilization of the upper thoracic and cervical spine as compared with a Minerva jacket. The halo is now a routine part of our armamentarium for the treatment of this type of scoliosis. Only twice have we needed to remove the halo early because of recurrent pin irritation, and this only after two to three months' wear. There was no loss of correction in either case. The type of scalp most likely to cause trouble is that which is oily or redundant. The residual sear from the pin in all patients has not been more than a one-eighth of an inch dimple, which quickly fades into obscurity.
The alignment of the halo traction apparatus on the cast has been simplified by dividing the crossbar which is attached to the cast so that each upright may be adjusted individually. There have been no further alterations in technique or philosophy of management.