An improved halo for fixing facial fractures

Abstract

TRAUMATIC maxillary displacement in most cases is posterior and downwards in direction. The maxillary block slides under the curving base of the skull and comes to lie in the open bite position with varying degrees of posterior shift and impacfion. This position is often forcibly maintained by the spastic contraction of the injured pterygoid muscles, the externus pulling the block towards the temporomandibular joint and the internus aided by the masseter muscle pulling the back of the block closer to the descending ramus of the mandible. In the majority of cases this displacement is easily corrected by manipulation under general anaesthesia and the maxilla can be held in the corrected position by a light halo apparatus in the usual way. There are, however, cases that do not respond so readily ; some early ones and nearly all late ones. After a few days an unreduced fracture becomes daily more firmly fixed and continuous traction rather than forcible disimpaction becomes the only way to effect reduction. This has led to the development of a halo which can exert pressure on the displaced maxilla in any direction through the medium of two self tapping screws inserted in the premaxilla (Grocott and Wilson, I972). A number of different frame types were tried ; that finally selected is an adjustable but rigid structure which gives access to the vault of the skull and is comfortable to the patient in bed. Necessarily this means a heavier structure than the standard halo but the weight has been progressively reduced to about 350 gm. by the use of light alloy. The frame (Fig. I) consists of a horizontal metal platform conforming in contour to the forehead and adjustable side arms pivoted at the outer ends of the platform. The platform itself carries 2 insulating blocks or bushes which in turn carry the stainless steel frontal screw pins (Fig. 2). In the centre of the platform is a ball or universal joint which forms the pivot for a vertical extensible beam dropping down to the maxillary attachment. The joint is fully adjustable by screws so that the beam may rotate and swing in an antero-posterior or lateral direction in any combination. The pivoted side arms are adjustable by screws and can be locked in final adjustment by nut and bolt. They are drilled and can carry vertical arms if desired. The posterior ends are slotted to carry the nylon insulated bushes which hold the mastoid screw pins. It is very advantageous to have as short a length of screw pin as possible between the frame and the skull. This ensures greater rigidity and obviates movement of the pin carriers or bending of the pins under stresses tangential to thc ~t'ull The skull strong points selected for insertion of the pins are on each temporal ridge area and each mastoid area at the level of the floor of the anterior fossa. The pin holders are first adjusted for position and then the angles are set for radial contact with the bone. The clamp is applied so that the mastoid pins register just in front of the mastoid suture line with the occipital bone; there is a depression here which is easily felt behind the ear. The lateral arms are tightened until the pins register against the bone in the depression. The pins, which are hollow ground, are screwed in a few turns until the whole clamp can be hinged up and down with the frontal pins just clearing the forehead. The frontal pins are now screwed home to register just above the superciliary ridges and just medial to the temporal ridges of the frontal bone. When these and the mastoid pins are tightened the platform is solidly fixed to the base of the skull.