Custom-Fitted Protective Headwear
GREG BELBIN, CO(C)* AND BRIAN GIAVEDONI, BSc, CP(C)
Most prefabricated helmets are designed for protection against athletic mishaps. A child or young adult who suffers from recurrent maxillofacial injuries as a result of failing requires a more intimately fitted helmet. The helmet prescribed at The Hugh MacMillan Medical Centre is a hybrid of several experimental models with the best features of each incorporated in the current design.
Patients requiring protective headwear usually present neuromuscular disorders or grand mal seizures or self injury Neuromyopathies may disrupt balance and coordination to the extent that walking is unsteady and dangerous. A patient with cerebral palsy (Fig. 1 ) has difficulty maintaining her balance. In an attempt to prevent serious maxillofacial damage. we fitted her with a hockey-type helmet complete with wire face guard and mandibular cup. The helmet was too loose and impaired her peripheral vision so much that she had several falls resulting in facial trauma and hospitalization. The helmet designed for her has polyethylene foam pads over the chin and forehead to provide excellent protection against injury in the event of a fall. By eliminating the face guard, the potential for falls related to impaired field of vision was reduced (Fig. 2 ).
Custom-Fitted Protective Headwear
Individuals with grand mal seizures have high potential for head and facial injury. One young man who has epileptic seizures was also fitted with a hockey helmet having a plastic face shield and semirigid chin cup. With the helmet, he sustained a fractured nose when the forehead portion slid down onto the bridge of his nose during the impact occurring at the time of a fall. His new custom helmet offers maximum facial protection without the use of a face guard. Hearing and peripheral vision are unimpaired. Fenestrations in the top of the helmet substantially increase heat dissipation (Fig. 3 ).
Patients requiring protection against self injury include a 7 year old boy with Lesch Nyhan syndrome (Fig. 4 ), characterized by biting and chewing fingers and other soft tissues. We designed a helmet and face shield that prevented him from biting his shoulders and arms. To prevent him from damaging his fingers, it was necessary to fabricate a pair of limited motion elbow orthoses which allowed a maximum of 40 degrees of elbow flexion.
Assessment is the first phase of fabricating the helmet. Need for protective headwear is established by the patient's falling pattern and diagnosis, as well as by consultation with parents and any other caretakers. Two balaclava-type stockinettes are placed over the patient's head. In order to determine how much protection is needed, the orthotist holds a straight edge at the tip of the patient's nose and measures the distance from the straight edge to the forehead, and from the straight edge to the chin. The average measurement provides maximum protection. A bivalved cast of the child's head is then taken. The positive mold is modified; minimal modifications are needed if an accurate cast has been obtained. Minor stockinette lines can be screened off easily. With the cast positioned in the oven, 2.5 cm (I inch) polyethylene foam, such as Plastazote, is vacuum formed over the anterior and posterior halves.
The design and shape of the liner is determined by the failing pattern of the patient. For example, if 2 cm (3/4 inch) is deemed sufficient protection against injury, the frontal and mandibular portions must project at least that distance from the patient's face. Other areas of the liner which are not likely to sustain impact are trimmed to within 8 MM (5/16 inch) to reduce the weight and bulkiness of the helmet. Contoured openings at the top of the liner reduce heat and discomfort by providing ventilation (Fig. 5 ).
Once the liner has been designed, Plastazote may be secured to the cast. All recessed areas are leveled with plaster to prevent undue compression of the foam at the borders. Polyethylene spacers are mounted at the midline above or close to the ears to provide offsets for attachment of Fixloc fasteners.
When completed, the helmet must fit snugly and not impair peripheral vision or jaw motion. A positive fit can be achieved by cupping the plastic under the chin and occiput. Full neck flexion and extension should be permitted with a 0.5 to I CM (3/16 to 3/8 inch) clearance around the ears to avoid irritation. Fasteners should be secured only after a positive fit has been achieved on the patient.
Custom helmets are very easy to clean, weigh approximately 280 grams (10 ounces), and permit total peripheral vision. More than 90 patients have been fitted with this type of protective headwear during the past three and a half years without any serious injuries reported while the patient wore the custom helmet.
*Prosthetic/Orthotic Service Department, The Hugh McMillan Medical Centre, 350 Rumsey Road, Toronto, Ontario M4G 1R8