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Halo Orthosis

- See:
      - Cervical Spine Menu:
      - Halo Placement in Children:

- Discussion:
    - most effect orthosis for controling motion at C1-C2 articulation;
    - contra-indications:
           - unstable skull frx;
           - traumatized skin overlying pin sites;

- Technique:
    - positioning of patient:
           - placement begins by positioning the patient (still on the spine board and still with semirigid collar in place) at the end of the bed so that the
                     head over hangs the bed;
           - head is stabilized manually w/ axial distraction during this maneuver;
           - while one M.D. continues to stabilize spine, the back panel is slid under pt's back between the scapulae in direct line w/ his neck;
           - occipital support, is then attached to back panel and tightly secured;
           - semirigid collar is left in place throughout;
    - size the halo:
           - once the head is supported, appropriate sized halo ring is selected;
           - it is placed in approximate position desired, and secured to occipital support by means of halo suction cups;
    - selection of holes:
           - optimum postioning of the halo is critical to ensure stability, durability and patient comfort;
           - 4 holes are placed in the scalp, 2 anteriorly and 2 posteriorly;
           - anterior pin sites:
           - posterior holes:
                  - placed about 1/4 inch above the ears;
                  - this placement of halo ensures that it will be below maximum diameter of skull and the will not migrate superiorly;
    - in the report by Nemeth et al, the authors investigated the use of six pins in halo application, in order to determine if 
           the extra pins increased fixation strength without increasing the overall pin-site complication rate;
           - first part of the consisted of force-deflection tests conducted on models of the skull fitted with either a four or a six-pin halo to 
                  determine if the six-pin halo provided greater fixation strength;
                  - in the force-deflection tests, the mean load to failure of the six-pin halo construct (2879 N [647 lb]) showed the system to be significantly stronger (p = 0.0033)
                         than the four-pin halo construct (1681 N [378 lb]);
           - second part of the study was a retrospective analysis of sixty-three patient records to document the prevalence of pin-site 
                  complications in patients treated with a six-pin halo system;
                  - these findings were then compared with established complication rates associated with four-pin halos;
                  - of the sixty-three patient records reviewed, five (8% [95% confidence interval, 1% to 15%]) revealed pin-loosening;
                  - no infection was recorded for these five patients.
           - 6-pin halo fixation results in greater halo strength and cervical spine stabilization without increasing the risk of pin-site complications;
           - ref: Six-Pin Halo Fixation and the Resulting Prevalence of Pin-Site Complications.  
    - pin insertion:
           - once the pin positions are selected, the pins are inserted;
           - it is not necessary to incise the skin w/ a scapel, and posteriorly it is not necessary to shave the patient's hair;
           - have patient close eyes during pin insertion;
           - each pin should be placed until they just touch the skin;
           - one front pin and the diagnonally opposite back pin are tightened to maximum finger tension;
           - other pins are likewise tightened;
           - torque screw driver is then used to tighten the pins, again tightening them in pairs first;
           - consider 6 to 8 in-lbs of tightness (10 in-lbs will begin to pass thru the outer table);
           - unequal tension should not be used as the halo will migrate in the direction of the pin of least tension;
    - pin care:
           - pins should be tightened carefully once a day for 3 days, and then checked for tightness every 3 days 3 more times;
           - pins should not routinely be tightened more than a full turn at any visit;
                  - this may indicated loose pin which has migrated into skull's inner table;
                  - if such a pin has a torque far less than the optimum, it should be removed and a new one placed.
                  - in this case, the diagonal opposite must be changed;

- Traction: (see unilateral and bilateral interfacet dislocation);
    - amount of traction needed for reduction of cervical frx or dislocation can be estimated as ten pounds to distract head & five pounds for 
           each interspace;
    - thus C4-C5 frx dislocation would probably require 30 lbs of traction;
    - initially start out w/ < this & work upwards after serial radiographs;

- Complications:
    - palsy of sixth cranial nerve (abducens);
    - loosening:
            - if pin does not appear to be infected, it can be retightened by carefully apply a few turns upto the desired 8 in-lbs

The halo skeletal fixator. Principles of application and maintenance.

The effect of halo-vest length on stability of the cervical spine. A study in normal subjects.

Halo-vest treatment of unstable traumatic cervical spine injuries.

Application of the halo device for immobilization of the cervical spine utilizing an increased torque pressure.

Subdural abscess associated with halo-pin traction.

Complications in the use of the halo fixation device.

The halo-Ilizarov distraction cast for correction of cervical deformity. Report of six cases.

Cervical orthoses: A study comparing their effectiveness in restricting cervical motion in normal subjects

Complications of halo fixation of the cervical spine. 

The effect of pin location on the rigidity of the halo pin-bone interface.

Incidence of and Risk Factors for Complications Associated with Halo-Vest Immobilization: A Prospective, Descriptive Cohort Study of 239 Patients