Review Question - QID 218936

Anterior pins inserted during application of halo traction should be placed 1cm above the orbital rim and in the superolateral two-thirds above the orbit, at least 4.5 cm lateral from the midline.

Halo traction apparatus placement in pediatric scoliosis is sometimes used before more definitive surgery in order to help decrease curve values, theoretically making surgery more likely to be successful. This said, complications are possible with halo traction placement. In pediatric patients, more pins (6-8 total) should be placed with less torque (2-4 in-lbs of pressure). With regards to anterior pin placement, they should be placed superior to the eye, lateral to the frontal sinus, supratrochlear nerve, and supraorbital nerve. Abducens palsy can also occur commonly with halo traction but it is important to understand this is not directly injured during pin placement, rather as a result of excessive traction.

Bono et al. reviewed halo fixators for the JAAOS, noting that it is versatile in its uses including spinal deformity, stabilization and definitive treatment in some cervical spine trauma. They discuss absolute and relative contraindications and recommend that a CT should be obtained in all children prior to placement to ensure adequate cranial bone thickness. Complications include, pin loosening, neurologic compromise, pin site infection, skin breakdown, and in elderly patients, respiratory issues.

Semmelink et al. looked at parameters for safe placement of halo gravity in the temporal bone in children with spinal deformities. They noted that with regards to resistance to pin failure/migration, the position just antero-cranial to the auricle was strongest. They concluded that with recommended applied tightening torque (2-4 lb-in), fixation in the temporal bone was strong enough to resist loosening forces.

Botte et al. also reviewed techniques for halo application in a JAAOS article. They noted that relative safe zone for anterior pin placement is 1 cm above the orbital rim and in the superolateral 2/3 of the orbit. They state that posterior pin site locations are less critical but should be diagonal to the contralateral anterior pins for good fixation.

Figure A shows the appropriate position (superolateral quadrant), for halo pin placement, depicted by the red circles. Illustration A redemonstrates safe zone pin placement, but also shows the corresponding nerves that are endangered with inappropriate pin placement.

Incorrect Answers:
Answer 1: Abducens nerve (cranial nerve VI) palsy, is thought to be secondary to traction injury, rather than direct injury from pin placement.
Answer 2: Injury to the temporalis muscle via too lateral pin placement can cause temporomandibular dysfunction, jaw pain, and headaches.
Answers 3 & 4: The supraorbital and supratrochlear nerves are both terminal branches of the trigeminal nerve (CN V) that provide sensory innervation to the skin of the forehead and upper eyelid. The supratrochlear nerve distribution is slightly more midline than that of the supraorbital nerve. Both can be injured if pins are placed too far medially.