**6. Posture and spinal coupling**

Postural rotations and translations as described by Harrison (**Figures 2** and **3**) are understood as 'main motions' and the corresponding spinal displacements to accommodate the postural positions are termed 'coupled motions' [2, 3, 35–38]. In CBP, a considerable clinical significance is placed on the correlation between the patient's three-dimensional postural presentation (posture displacement in terms of rotations and translations) and the two-dimensional X-ray coupled motion (spinal rotations and translations) [2, 3, 38].

Of prime importance is the appreciation that unless there is buckling, anomalies or ligament damage, standing neutral postural rotation and translation displacements of the head or thorax *cause* the vertebral spinal coupling patterns as seen on X-ray. If a patient's rotations and/or translations of posture 'match' the associated spinal coupling pattern as expected (i.e. normal coupling), then it is considered an 'easy' or typical case and the intuitive mirror image application of CBP methods would apply. When the patient's rotations and/or translations of posture do not match the expected spine coupling pattern (i.e. spinal coupling does not match postural displacement), then it is considered an atypical case where the clinician needs to consider alternative (i.e. more complicated) strategies for spine rehabilitation.

A classic demonstration of the 'matching' versus 'mismatching' of rotations and translations of posture and spine coupling patterns can be illustrated with forward head posture, aka, anterior head translation (AHT) (**Figure 11**). The natural and expected spine coupling with a forward translated head posture involves lower cervical spine flexion and upper cervical spine extension. As seen in **Figure 11**, many

#### **Figure 11.**

*Forward head translation as shown in posture and in three unique lateral cervical radiographs. All three X-ray images have about 25 mm of forward head translation. Left: hyperlordosis; middle: hypolordosis; right: kyphosis. Green line is normal alignment; red line highlights patient alignment.*

spine different vertebral coupling patterns are possible including hyperlordosis, hypolordosis, or kyphosis and accordingly, each cervical configuration requires its own unique application of CBP methods for its ideal correction.

These cervical spine patterns have been termed harmonics and their presence can only be determined by radiography [2, 39]. Importantly, in CBP treatment approaches, each cervical spine coupling pattern (harmonic) requires its own unique treatment protocol. This is why many manual therapy approaches (e.g. Mackenzie head retractions) are inadequate at correcting posture and spine alignment as these are prescribed universally (i.e. 'blackbox treatment') resulting in many patients receiving treatment protocols that are contraindicated. A patient with a hyperlordotic cervical spine should never be prescribed neck extension exercises as this would dynamically hyperextend the cervical joints. A patient with a complete cervical kyphosis should never be prescribed head retraction exercises as this often 'buckles' the spine into further kyphosis.

Also, as mentioned and illustrated in **Figure 6**, 'pseudo-scoliosis' or pure lateral translations of the thorax (or head) must be distinguished from true scoliosis by examination of the spinal coupling patterns [14]. If there is minimal or no vertebral rotation then this represents a typical case requiring CBP mirror image postural correction [3]. If there is vertebral rotation then it is considered true scoliosis and a completely different application of CBP methods (i.e. non-commutative properties of finite rotation angles [40, 41]). Case examples of the special application of CBP methods in the treatment of scoliosis is described later.
