The halo traction device is a specialized medical apparatus designed to stabilize the cervical spine and strictly limit its movement. This system is primarily employed to treat severe instability of the upper cervical spine, such as complex fractures or major ligamentous injuries, where rigid external immobilization is necessary for healing. Attaching this device is a precise medical procedure that transforms the head and torso into a secure, single unit, preventing motion that could otherwise damage the spinal cord. This external fixation achieves powerful immobilization through meticulous steps and specific components.
Essential Components of the Halo Apparatus
The halo apparatus consists of three main parts that work together to achieve rigid fixation. The halo ring is a lightweight, circular metal band, often made of carbon fiber or titanium, which encircles the patient’s head without touching the scalp. This ring is the anchor point for securing the head and must be sized to allow a slight clearance of about one to two centimeters from the skin.
The fixation pins are the second component, typically four sterile screws for adults, that pass through the halo ring and secure it to the outer table of the skull bone. The vest, or jacket, forms the third component; it is a rigid plastic shell, often lined with soft material, that fits snugly over the patient’s torso, acting as the foundation for the bracing system. Upright metal rods then connect the halo ring to the vest, completing the rigid frame that immobilizes the cervical spine.
Patient Preparation and Initial Steps
The attachment process typically takes place in a specialized setting, such as an operating room, to maintain a sterile field. Before applying hardware, the medical team measures the patient’s head to select the correct halo ring size and the appropriate vest size. The skin at the planned pin insertion sites is then prepared by trimming hair and thoroughly cleaning the areas with an antiseptic solution to minimize the risk of infection.
The insertion sites are strategically chosen to avoid sensitive structures and maximize stability. For an adult, this usually involves two anterior sites and two posterior sites, positioned diagonally across from each other. Local anesthesia, often lidocaine, is carefully injected at these four predetermined pin locations to numb the skin and the periosteum covering the skull bone.
Securing the Halo Ring to the Skull
With the halo ring temporarily held in position, the permanent fixation pins are advanced through the ring and onto the cranium. The anterior pins are carefully chosen, placed about one centimeter above the lateral third of the eyebrows to avoid the temporal muscles and sensitive nerves. Positioning the patient’s head to keep the eyelids closed during this step is necessary to prevent skin tension that could cause the eyelids to remain partially open later.
The posterior pins are generally placed in the thicker bone of the occipital region, approximately five centimeters behind the top of the ear. The pins are first hand-tightened through the skin until they make solid contact with the skull. The most critical step is the final tightening, which is achieved using a specialized torque wrench set to a precise pressure, typically eight inch-pounds for an adult. This measured torque ensures the pins firmly anchor the ring to the outer layer of the skull without risking penetration of the inner table. After the initial tightening, the pins are checked and often retightened to the same eight inch-pounds approximately 24 to 48 hours later to account for any initial settling of the skin and bone.
Connecting the Ring to the Vest
Once the halo ring is securely fixed to the skull, the final assembly connects the ring to the torso foundation. This is accomplished using upright metal rods attached to the halo ring and secured to the plastic vest worn around the chest. The vest is sized and fitted snugly against the patient’s body, and it may be composed of anterior and posterior shells secured by straps, which distributes the forces over the torso.
The upright rods must be meticulously adjusted for length and angle to achieve the desired alignment of the cervical spine. In cases requiring spinal realignment, the connection may be adjusted to apply gentle traction or counter-traction force. Following the attachment of the rods, X-rays are immediately taken to verify that the cervical spine is in the correct position and that the alignment has been maintained by the newly assembled brace. This final connection establishes the rigid stability necessary for healing by locking the head and neck into a fixed position relative to the torso.