Changes in circumferential neck measurements during movements of the head in children and their relevance to extraoral traction

One of the causes of facebow injuries to patients wearing extraoral tractio n has been the catapult effect of the simple elasticized materials used in the past. A variety of safety or self-releasing modular systems to countera ct this catapult effect are currently available. However, the strap extensi on provided by these modules varies considerably. To reduce the catapult ef fect to a minimum, it is desirable to fit a system with the minimal travel that will accommodate any changes in distance between the facebow and the b ack of the head or neck. To ascertain the minimal travel required for the s traps, circumferential neck measurements were carried out on 105 children a ged between 9 and 14 years. The change in circumference was recorded for 3 different head positions. The mean distance change between the back of the neck and the end of the facebow was 25 mm per side, with a range of 4 mm to 50 mm. This study suggests that on average, modules with a 25-mm extension will be required for cervical traction.