Halo Vest Application and Management

Contemporary indications (narrowing as instrumentation improves):

• C1 ring (Jefferson) fractures with an intact transverse atlantal ligament — Dickman type-based assessment on MRI or lateral mass overhang on open-mouth view. Intact ligament (typically total overhang less than 7 mm by the Spence rule, corrected) is a halo or collar problem; a bony avulsion may heal in a halo whereas midsubstance ligament rupture usually requires fusion.
• Odontoid fractures — type III routinely; selected type II in younger patients with minimal displacement where surgery is declined or unsuitable. Nonunion risk factors: age (older), displacement greater than 5 mm, angulation greater than 10 degrees, posterior displacement, comminution, delayed presentation.
• Hangman (traumatic spondylolisthesis of C2) variants — Levine-Edwards type I and reduced type II after traction/extension positioning; type IIa (flexion-distraction, do NOT apply traction) and type III require surgery.
• Paediatric cervical trauma — children tolerate halo well, heal fast, and often avoid fusion of a growing spine.
• Adjunct after complex cervical reconstruction — revision occipitocervical fusion, poor bone quality, resections, infection.
• Gradual deformity correction / halo traction — severe rigid kyphoscoliosis or basilar invagination, preoperative halo-gravity traction.
• Temporising stabilisation in the polytrauma patient not yet fit for definitive cervical surgery.

Safe zone: 1 cm superior to the orbital rim, over the lateral two-thirds of the supraorbital ridge (practically the lateral third of the rim), below the skull equator, and anterior to the temporalis muscle.

Practical marking: ask the patient to look straight ahead; the safe target lies above the outer canthus/lateral eyebrow, not above the pupil.

Posterior pins are placed diagonally opposite their anterior partners, approximately at the 4 and 8 o'clock positions on the ring — posterolateral, above and behind the ear, below the skull equator, over thick parieto-occipital bone.

• Hair may be parted rather than widely shaved.
• Avoid pressure directly on the ear or mastoid.
• Diagonal pairing (right anterior with left posterior) creates the compressive vector that keeps the ring centred.

• Skull is thinner and more compliant; single-point loads penetrate.
• Use more pins at lower torque: typically 6 to 8 pins at 2 to 4 inch-pounds, often "finger tight".
• Under 2 years or in dysplastic/syndromic skulls: preoperative CT of the skull to map thickness and plan pin sites; consider a custom ring and multipoint low-torque fixation.
• Children tolerate the halo remarkably well and remodel/heal quickly, which is why halo remains a genuinely first-line paediatric option.
• Watch for pin-site infection (higher rate in children) and for the child dislodging the vest during play.

Position — Supine on a trolley with the head supported off the end on a board or held by an assistant maintaining manual in-line stabilisation; the occiput must be accessible for the posterior half of the vest. Alternatively sitting for cooperative, neurologically intact patients.

Imaging/equipment — Fluoroscopy or a portable lateral radiograph available to confirm alignment during and after application. Ring, uprights, vest, torque screwdriver (calibrated), sterile pins, local anaesthetic, antiseptic.

Preparation — Mark the four pin sites with the ring held in position (below the equator, 1 to 2 cm clearance, level, and clear of the ears). Infiltrate local anaesthetic down to periosteum.

Approach — Percutaneous; no incision. Position the ring using temporary positioning pins/blocks so it does not need to be repositioned once pins engage.

Dissection/Insertion — Advance each pin perpendicular to the skull through skin and periosteum until bone is engaged. Perpendicularity matters: an obliquely applied pin skives on the outer table, loosens early and concentrates stress.

Reduction — Achieve and hold the desired cervical alignment BEFORE final locking of the uprights. Extension improves most odontoid and type I hangman patterns; avoid traction/extension in type IIa hangman injuries (flexion-distraction) where distraction worsens displacement. Confirm with imaging with the halo held, then lock.

At-risk structures — Supraorbital/supratrochlear nerves, frontal sinus, temporalis and squamous temporal bone, globe, dura and underlying cortex, skin under the vest, brachial plexus if the vest is over-tightened at the shoulders.

Fixation/torque — Tighten diagonally opposed pairs simultaneously in incremental turns to keep the ring centred:

• Adults: 8 inch-pounds with a calibrated torque screwdriver.
• Children: 2 to 4 inch-pounds across 6 to 8 pins. Apply locking nuts against the ring to prevent back-out.

Vest application — Log-roll to place the posterior shell, then apply the anterior shell; do not lose the alignment. Connect uprights, tighten so the head is neutral (or in the planned corrective position), and check the patient can open the mouth, swallow and breathe comfortably. Over-extension causes dysphagia and aspiration — a common, avoidable error.

Closure/documentation — Record pin sites, torque used, alignment achieved, neurological examination after application, and the date for the single retorque check.

Aftercare

• Imaging immediately after application and after any adjustment.
• Repeat neurological examination.
• Erect radiograph once mobilising — alignment often changes from supine to upright.
• Written pin-care instructions, tools taped to the vest (or the wrench for anterior chest access in a cardiac arrest), and 24-hour contact details.

Pitfalls — Ring too high (migration), pin too medial (nerve/sinus), pin oblique (loosening), vest too loose (loss of control), neck over-extended (dysphagia), no post-application imaging (silent malalignment).

Salvage — Loose pin: exchange to a fresh adjacent site rather than repeatedly retorquing. Persistent loss of reduction, nonunion at follow-up, or intolerance: convert to internal fixation.