Cervical orthosis could be prefabricated or custom made.
Prefabricated cervical orthoses are of two basic types : collars and post appliances.
There are a lot of other custom made designs.
Apart from serving a reminder to the wearer to restrict head and neck motions, depending on design and fit, a particular orthosis may impose forces to position the head, limit flexion, extension, rotation, and/or lateral motion of the head and cervical spine, and reduce load on the cervical spine by supporting a portion of the weight of the head.
How Effective is Cervical Orthosis
The ability of cervical orthoses to control motion varies greatly. For example, at one end of the scale is the soft collar, which provides only slight mechanical restraint, while at the other end are custom-molded and halo-type orthoses that provide marked restriction of motion in all directions. Other appliances fall in between the two extremes.
Prefabricated Cervical Orthoses
Flexion-extension ( F-E) Control Orthoses
Collars are devices that wrap around the neck and are adjustable circumferentially. The basic collars may have provision for height adjustment, be single or multiple layered, and of variable firmness. Materials used include resilient polyethylene foam,sponge rubber, and felt, as well as rigid polyethylene sheeting. Collars are usually prefabricated, although custom-made versions can be prescribed.
Depending on the type of material used, the collars could be labelled as soft or hard collars.
Collar provide some mechanical restriction of forward flexion and extension and, to a lesser degree, lateral flexion and rotation. They remind the wearer to limit head and neck motions. They also retain body heat, which may aid healing of soft-tissue injuries and reduce muscle spasm.
Collars are usually used for soft-tissue injury and/or arthritic changes.
Cervical foraminae open in flexion and close in extension, the collar is fitted high in the back so that it fits well under the occiput, in order to increase resistance to extension or hyperextension. For greater control, a madibular support may be added to the rigid collar.
Prefabricated collars may be difficult to fit comfortably. Such problems can be solved usually by custom fabrication of a collar.
It offers more control of motion, as compared to the basic collar.
Prefabricated of polyethylene foam with rigid anterior and posterior plastic strips, this device covers more of the head and neck than basic collars. The Philadelphia Collar terminates superiorly over the mandible and at the occiput. Its lower border is at the proximal thorax.
Apart from being a reminder to limit neck motion, the reinforcement provided by the anterior and posterior plastic strips enables this orthosis to provide greater restriction to cervical flexion, extension, rotation, and lateral bending than that provided by soft collars.
The anterior and posterior plastic reinforcing strips permit more selective adjustment of head position than that provided by soft collar.
Flexion- Extension and Rotary (F-E-R) Control Orthoses
Sterno-Oocipital-Mandibular-immobilizer ( SOMI)
This orthosis is a post type device but unique in that the uprights which maintain the position of the occipital support arise anteriorly from a sternal plate. Because of this arrangement, the SOMI can easily be applied to the supine patient and permits the wearer to lie on his back comfortably.
The single anterior upright, with its attached mandibular support, can be quickly and easily removed irom the sterna plate. This also allows the patient to eat, wash, or shave while remaining in a supine, semi immobilized position.
The SOMI provides approximately the same control of cervical flexion and rotation as do other post appliances, although control of cervical extension and lateral bending is significantly less.
A prefabricated polyethylene and Dacron skull strap, can be substituted for the mandibular support. The strap, which allows the patient to chew, yet provides some flexion control, snaps onto the occipital support and encircles the upper skull. it is used primarily to permit eating and not as the definitive treatment.
Fixtures are available to enable the SOMI to be attached to a custom-made spinal jacket, thus increasing overall orthotic control of the vertebral column.
Post appliances have an anterior section consisting of a sternal plate, one or two uprights, and a mandibular support, as well as a posterior section consisting of an interscapular plate, One or two uprights, and an occipital support.
A four-post appliance, although slightly bulkier than one with fewer posts, provides somewhat better control of lateral motion. The anterior and posterior sections are usually connected by straps between the mandibular and occipital supports and by shoulder straps between the interscapular and sternal plates.
Axillary straps from the sternal to the interscapular plate may be added to increase the stability of the orthosis. The uprights are adjustable for height. Angular position of plates can be adjusted by means of the swivel attachments between uprights and plates. The orthosis is commonly prefabricated of aluminum with plastic or leather padding of the parts which contact the body.
A post appliance restricts flexion and extension of the head and cervical spine by forces applied under the mandible and occiput.
It limits lateral flexion and rotation by forces at the mandibular and occipital supports. Adjustment of lengths of uprights can relieve the cervical spine of some portion of the weight of the head.
If a post orthosis cannot be tolerated, the same functions can be provided (to a lesser degree) by adding mandibular and occipital supports to a rigid collar
For greater motion control, adding a custom-made rigid attachment between the mandibular and occipital supports and by increasing the superior contact ares with a large, custom-molded mandibular support.
Extending the thoracic section further downward can improve fixation controls cervical flexion and extension better than or orthoses that cover only the uppermost trunk.
Custom-molded appliances are designed to markedly restrict all neck motions and can also restrict thoracic motion to varying degrees, depending on the extent of their downward extension on the thorax.
Those that extend distally beyond the upper thorax are classified as cervicothoracic orthoses. These custom-molded orthoses may be made of high-temperature thermoplastic or leather formed over a modified plaster model of the patient’s skull and torso, or low-temperature thermoplastic formed directly on the patient.
It Applies stabilizing forces under and around the chin and occiput to restrict flexion and extension, lateral motion, and rotation of the head and cervical spine.
It positions the head and relieves the cervical spine from a portion of the weight of the head.
It may limits thoracic motion to varying degrees.
The cuirass type ) extends superiorly over the chin, mandible, and occiput.
Its lower limits may terminate about one inch above the inferior angles of the scapulae or may continue further downward to the interior costal margin, depending on the degree of control required.
It encloses the entire posterior skull and includes a band around the forehead, extends downward to the inferior costal margin or, if greater control of cervical and thoracic motion is indicated, it may terminate in a pelvic girdle.
The halo assembly provides the greatest control of all cervical appliances. The basic components of this orthosis are the halo ring, distraction rods, shoulder dars, and a distal fixation component. The halo encircles the skull and is secured in place by fixation pins that penetrate several millimeters into the skull. The upper and lower ends of the length-adjustable distraction rods are attached, ospectively, to the halo and to the shoulder bars which, in turn, are attached to a distal fixation component which may be a vest, body jacket, pelvic girdle, pelvic hoop, or femoral transfixing pins.
It is able to rigidly fix the head with respect to the thorax.
Provides distracting force that aids in spinal stabiliaation and in redncing the load of the head on the cervical spine.
Amount of axial load reduction depends on upward force applied to the head by the distraction rods.