Cranial Tongs & Halo Application (Cervical Traction and Halo-Vest Immobilisation)

Indications

Gardner-Wells Tongs

• Closed reduction of cervical facet dislocations (unilateral or bilateral) — serial weighted traction with neuromonitoring
• Temporary cervical traction to realign and provisionally stabilise an unstable subaxial injury before definitive surgery
• Restoration of length/alignment in burst fractures and fracture-dislocations awaiting fixation
• Intra-operative traction to aid reduction and positioning

Halo Ring & Vest

• Definitive non-operative immobilisation of selected upper and subaxial cervical injuries (e.g. some C1 ring/Jefferson fractures, selected odontoid type II/III fractures, Hangman's type I-II)
• Adjunct/provisional immobilisation before or after operative stabilisation, or to protect a fusion
• Most rigid external cervical orthosis — controls flexion-extension, rotation and lateral bending better than a collar or SOMI brace
• Paediatric cervical instability with appropriate pin-number/torque modification

Contraindications & Cautions

Traction (tongs/halo distraction):

• Absolute: cranio-cervical / atlanto-occipital dissociation (AOD) — axial pull can fatally distract the junction
• High risk: ankylosing spondylitis / DISH — rigid column over-distracts easily; reduce in pre-injury position with minimal force
• Caution: any injury where distraction may worsen alignment (Type IIA Hangman's flexion-distraction)

Halo vest:

• Relative: severe chest wall injury or pulmonary compromise (vest restricts respiration), elderly with poor reserve (high complication/mortality), uncooperative patient, cranial skull defects/cranioplasty at pin sites, severe obesity

Biomechanics

Why Pin Position Matters

• The skull is widest at the equator (greatest circumference). Pins placed BELOW the equator are pulled INTO the skull by axial traction and resist slippage; pins ABOVE the equator are pulled OFF.
• Gardner-Wells tongs are spring-loaded with a pin indicator that protrudes about 1 mm at correct compression, giving consistent, symmetric force without over-penetration.
• The vector of traction can be adjusted (slight flexion/neutral/extension) to favour reduction of a specific injury pattern — facet dislocations often reduce with initial slight flexion then extension once unlocked.

Halo Construct Rigidity

• The halo is the most rigid external orthosis because it fixes the skull directly to the trunk via four rigid uprights and a well-moulded vest — eliminating the skin-and-soft-tissue slack that limits collars.
• It controls the upper cervical spine far better than the subaxial spine; "snaking" (segmental motion within the construct) still occurs at lower levels, which is why halo immobilisation fails in some unstable subaxial patterns.

Gardner-Wells Tongs — Step-by-Step

Step 1: Preparation and Pin Site

Position the patient supine on a bed capable of traction (e.g. with a pulley at the head). Clip/clean the pin sites. Local anaesthetic is infiltrated down to periosteum at each site.

The pin sites lie about 1 cm (one finger-breadth) above the pinna, in line with the external auditory meatus, and crucially below the equator (greatest diameter) of the skull. This position lets axial traction seat the pins firmly rather than pull the tongs off.

Step 2: Pin Insertion and Tightening

Insert the spring-loaded pins symmetrically and tighten the opposing pins until the spring-loaded pin indicator protrudes about 1 mm, confirming correct and symmetric compression. Do not over-tighten.

Step 3: Traction Protocol

Begin with about 4.5 kg (10 lb). After confirming a stable baseline neurological exam and a satisfactory lateral radiograph, add weight incrementally — a common rule is roughly 2.3 kg (5 lb) per cervical level of injury, added in steps.

After EVERY weight increment perform a focused neurological examination AND a lateral cervical radiograph. Continue until reduction is achieved or a limit is reached.

Step 4: Achieving and Holding Reduction

Facet dislocations are often unlocked with the neck in slight flexion, then the vector is changed toward extension once the facets disengage. When reduction is confirmed radiographically (and neurology preserved), reduce the weight to a maintenance load that holds alignment until definitive treatment.

Key Evidence

Halo Ring & Vest — Step-by-Step

Step 1: Ring Selection and Positioning

Choose a ring (or open-back crown) that clears the skull by about a finger-breadth all round. Position the ring below the skull equator, about 1 cm above the eyebrows and ears, lying just above the ears so it does not contact them.

Step 2: Anterior Pin Safe Zone

The anterior pins go into the safe zone: the anterolateral skull, below the greatest skull circumference, above the supraorbital ridge over the LATERAL two-thirds of the orbit. This position deliberately:

• Avoids the temporalis muscle laterally (chewing pain, trismus, thin squamous bone)
• Avoids the supraorbital and supratrochlear nerves medially (forehead/scalp numbness)
• Avoids the frontal sinus medially (CSF leak, sinus infection)

The patient closes the eyes during anterior pin tightening so the forehead skin is not tethered in a position that prevents the eyelids closing afterwards.

Step 3: Posterior Pins

The posterior pins are placed posterolaterally, diagonally opposite the anterior pins, below the equator. They sit in thicker bone and are generally lower risk, but should still be kept off any cranial defect or shunt.

Step 4: Tightening to Torque

Tighten opposing diagonal pins simultaneously (anterior-left with posterior-right, then anterior-right with posterior-left) to a torque of about 6 to 8 inch-pounds (roughly 0.7 to 0.9 Nm) in adults, using a torque-limiting screwdriver. Lock the pins.

Step 5: Vest Application and Connection

Apply the well-fitting vest (sized to the chest), padded over bony prominences. Connect the ring to the vest with four rigid uprights, adjusting cervical alignment (flexion/extension/translation) under lateral fluoroscopy or radiograph before final tightening.

Step 6: Re-torque and Maintenance

Re-torque the pins ONCE at about 48 hours (bone settles), then do not routinely re-torque. If a pin loosens later it is managed individually (see Complications). Provide the patient/family with a wrench taped to the vest for emergency CPR access (front panel removal).

Key Evidence

Pin-Site Care Protocol

• Clean each pin site (e.g. chlorhexidine or saline per local protocol) on a regular schedule
• Inspect daily for erythema, discharge, looseness or pain
• Keep hair short around pin sites; avoid crusting build-up
• Re-torque ONCE at about 48 hours; thereafter do NOT routinely re-torque — a single loose pin is tightened once (if within early window) or replaced/relocated, not all pins repeatedly
• Keep an emergency wrench attached to the vest for rapid front-panel removal during CPR

Paediatric Halo Application

• The child's skull is thinner and softer, so load is spread over more pins at lower torque — commonly 8 to 10 pins at about 2 to 5 inch-pounds in young children (numbers/torque fall with younger age and thinner bone).
• Obtain a pre-operative CT of the skull to map bone thickness and the open sutures so pins avoid sutures, thin squamous bone and the still-developing frontal sinus.
• The same anatomical safe-zone principles apply (anterolateral anterior pins, posterolateral posterior pins; avoid temporalis, supraorbital nerve, sinus).
• Pins are generally not re-torqued in children; loose pins are managed individually.

Ankylosing Spondylitis & DISH

• The fused, brittle column behaves like a long bone; even minor trauma produces highly unstable three-column injuries.
• Traction over-distracts dangerously — reduce in the patient's pre-injury (often kyphotic) alignment, use minimal or no traction, and image frequently.
• A halo vest forced into a "neutral" position can worsen deformity and injure the cord; many of these injuries require operative stabilisation.

Atlanto-Occipital Dissociation

• Traction is contraindicated — axial pull can lethally distract the disconnected occipito-cervical junction.
• Recognise on imaging with the Powers ratio, basion-dental and basion-axial intervals and the condyle-C1 interval (CCI) on CT.
• Immobilise (collar/careful halo without distraction) and proceed to occipito-cervical fixation.

MRI Compatibility

• Modern halo rings, pins and uprights are typically made of aluminium and titanium (MRI-compatible) rather than ferromagnetic steel, allowing MRI when needed — but confirm the specific device's MRI labelling and use MRI-conditional graphite/composite uprights and vest hardware where required.
• Check every component (ring, pins, uprights, vest fasteners) before entering the scanner; some older or mixed sets contain ferromagnetic parts.

Awake vs Obtunded Reduction

• Awake, examinable patient: serial weighted closed reduction with neuro exam after each increment is the classic safe pathway.
• Obtunded / unexaminable patient: many surgeons obtain an MRI before or during reduction to assess for a herniated disc and to allow safe monitoring, given the inability to detect a new deficit clinically.