Cervical spine

A number of authors describe the normal coupling at the occipito-atlantal (C0–1) segment as axial rotation and lateral bending to the opposite side (i.e. Type 1 movement).^7,9,10 The principle of facet apposition locking does not apply to HVLA thrust techniques directed to the C0–1 segment. However, facet apposition locking of the C0–1 segment can be utilized for HVLA thrust techniques directed to other cervical levels (Table 4.1).

Table 4.1

The type of coupled movement available at the C1–2 segment is complex. This segment has a predominant role in total cervical rotation.^11–14 Up to 77% of total cervical rotation occurs at the atlanto-axial joint, with a mean rotation range of 40.5° to either side.^11,13 The great range of rotation at the atlanto-axial joint can be attributed to facet plane, the loose nature of the ligamentous fibrous capsule and the absence of ligamentum flavum above C2.¹⁴ Only a small amount of rotation occurs at the joints above and below the atlanto-axial joint.^15–17

Below C2, normal coupling behaviour in the cervical spine is Type 2 (i.e. sidebending and rotation occur to the same side).^7,9,18–22 The average range of cervical spine rotation from neutral position is 80° (Fig. 4.3).²³ For patient comfort and safety the practitioner should limit the total range of cervical spine rotation when applying thrust techniques. Below C2 this is achieved by combining cervical spine rotation with opposite sidebending (Fig. 4.4). To generate facet apposition locking for HVLA thrust techniques, the operator must introduce a Type 1 movement, which is sidebending of the cervical spine in one direction and rotation in the opposite direction (e.g. sidebending right with rotation left). This positioning locks the segments above the joint to be cavitated and enables a thrust to be applied to one vertebral segment. The amount or degree of sidebending and rotation can be varied to obtain facet locking. The intent should be to have a primary and secondary leverage. The principal or primary leverage can be either sidebending or rotation (Fig. 4.5).

Figure 4.3 Full left cervical spine rotation.

Figure 4.4 Introduction of right sidebending limits the range of available left cervical spine rotation.

Figure 4.5 Cervical HVLA positioning for up-slope gliding thrust. Primary leverage of rotation to the left and secondary leverage of sidebending to the right achieve facet apposition locking down to the desired segment on the right.

The principles of facet apposition locking that apply to the cervical spine are also utilized for HVLA thrust techniques to the cervicothoracic junction (C7–T3). If cervicothoracic region techniques require locking via the cervical spine, this is achieved by introducing Type 1 movements to the cervical spine.