High/Low Factors, Levers and Wedges

High/Low Factors, Levers and Wedges

Roderic P. Rochester

Often models and concepts are used to explain complex biomechanical principles that are observed during the application of upper cervical chiropractic care. This chapter will discuss the use of high and low factors to help change the relative alignment of upper cervical structures in a predictable and controllable manner. High factors are used to help move anatomical structures away from the adjustor, whereas low factors aid in moving structures toward the adjuster. Also covered in this chapter are the biomechanical concepts of Levers and wedges as they relate to the upper cervical Adjustment.

High Factors

The patient is positioned in a side posture position on the adjusting table with the mastoid firmly supported on the Mastoid support and the side of Atlas laterality up. The axis spinous process can be rotated equal to, ipsilateral, or contralateral relative to the side of Atlas laterality—in other words, positioned with no rotation, rotated toward or away from the doctor who is preparing to deliver the Adjustment. An inferior spinous is one that is rotated toward the adjustor with the patient in the side-lying position. It should move away from the doctor in an inferior direction, toward the floor during the Adjustment. Likewise, with a large Lower angle (>3°) that is opposite Atlas laterality, the odontoid is misaligned toward the side of Atlas laterality relative to the atlas in most cases. To assist in moving these structures away from the adjustor, high factors are used following the Table placement of the patient into a neutral position and before the delivery of the vectored corrective force. High factors are:

  • A lower headpiece

  • A high line of drive (LOD)

  • A flatter headpiece

When a patient is in the side-lying position in the neutral posture, lowering the headpiece by ½ inch tends to initiate a slight lateral flexion at C1-C3 to the same side of Atlas laterality. The lateral flexion is coupled with the initiation of the axis spinous moving away from the side of Atlas laterality and is consistent with current knowledge of coupled motion (see Chapter 16). Rotation at C1-C2 is the most freely moveable intersegmental movement in the cervical spine and has the most sensitivity to slight lateral flexion in the upper
cervical spine. Care must be taken not to lower the headpiece more than ½ inch because while initiating the spinous movement in the intended direction as the headpiece is lowered slightly, going beyond ½ inch creates lateral flexion in the lower cervical spine in the opposite direction of Atlas laterality. This can create a locked coupled motion pattern that forces the Atlas laterality to increase as the headpiece goes down. This biomechanical phenomenon is observed in forced lateral head translation and simulates the affects of lowering the headpiece beyond ½ inch.1 A flatter headpiece is another high factor (see Chapter 12). Flattening the headpiece accentuates the affect of slight lateral flexion at C1-C3 ipsilateral to Atlas laterality, and this takes advantage of coupled motion to cause the axis spinous to move away from the adjustor. The last high factor is an exaggerated LOD, which increases Leverage against the axis vertebra from the atlas during the Adjustment, initiating a greater movement of the axis vertebra away from the adjustor.

Low Factors

With a patient in side-lying neutral position and the mastoid on the solid Mastoid support, the application of low factors are used for moving certain anatomical structures toward the adjustor during the Adjustment. An axis spinous process that is rotated opposite to Atlas laterality will need to turn toward the adjustor during the Adjustment and is called a superior spinous. This is because it must move toward the ceiling or in a superior direction and requires superior Torque during the hand Adjustment. Likewise, a large Lower angle (>3°) ipsilateral to Atlas laterality creates an odontoid that has moved opposite Atlas laterality relative to the atlas and needs to move toward the adjustor during the Adjustment to return to a neutral alignment. Using low factors following the neutral Table placement of the patient will help the doctor better correct these types of Subluxations. The low factors are:

  • A high headpiece

  • A sharp headpiece

  • A low LOD

Raising the headpiece after the patient is in the neutral Table placement initiates a lateral flexion at C1-C3 that is opposite or contralateral to Atlas laterality and causes the axis spinous to begin rotating toward the adjustor. Care must be taken to ensure a proper Mastoid support when raising the headpiece so as not to lock the vertebral Articulations in the upper cervical spine. Raising the headpiece creates a lateral translation of the occiput toward the direction of Atlas laterality and causes the atlas to slide away from the Atlas laterality with respect to the position of the occiput. Raising the headpiece beyond ½ inch initiates lateral flexion in the lower cervical spine on the same side as Atlas laterality. This creates a combination of opposite lateral flexion within the cervical spine, and the conflicting couple motion may lock the Articulations below the atlas, resulting in a poor correction of the odontoid, axis, and lower-angle measurements. Another low factor is a sharper headpiece (see Chapter 12). A sharper headpiece will accentuate the initiation of slight lateral flexion at C1-C3 opposite Atlas laterality and assist in moving the odontoid and spinous toward the adjustor. A low LOD shifts the force of the atlas during the Adjustment away from the axial surface toward the skull. This increases the comparative energy toward the occipital condyle, thus allowing the odontoid and axis to move toward the adjustor.

High and Low Factors for Upper Cervical Misalignment Patterns

Orthospinology has simplified complex misalignments patterns of the upper cervical spine into four basic categories: Types I, II, III, and IV (see Chapter 11). It is helpful to view the characteristics of each type by example and understand when to apply high or low factors (Tables 17-1, 17-2, 17-3 and 17-4). Type I requires the most force to reduce and Type IV the least force. The amount of force is controlled by the preload against the skin and not the amount of force from the contraction during the hand Adjustment. The preload is applied in a similar manner for the instrument Adjustment; however, the force can be slightly modified if necessary.

Levers and Wedges

The doctor is able to take advantage of Leverage because of the biomechanics involved with the use of a solid Mastoid support during the Orthospinology Adjustment. When a patient is in the side-lying position with the mastoid on a solid support, Gravity and a downward force against the atlas transverse process causes the atlas and skull to become Levers. These Levers can be used to the doctor’s advantage or disadvantage when modifying upper cervical alignment. It behooves doctors of chiropractic who employ a solid Mastoid support to have a thorough knowledge of the concepts of Levers and wedges to provide effective care for their patients. These concepts apply to adjusting forces sufficient to overcome the inertia of the masses involved and do not relate to nonforce techniques.

TABLE 17-1 Type I

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Jul 24, 2016 | Posted by in ORTHOPEDIC | Comments Off on High/Low Factors, Levers and Wedges

Full access? Get Clinical Tree

Get Clinical Tree app for offline access