For individuals suffering from chronic lumbar pain, many rehabilitative approaches have implemented the use of repeated lumbar extension or repeated lumbar flexion as an integral component of the treatment plan.
In the past, it was theorized that directional preference could be predicted based on the form of pathology: repeated extension should be prescribed to patients with disc pathology while repeated lumbar flexion should be prescribed to patients with spondylolisthesis or stenosis.
Unfortunately, this approach has not stood up to empirical evidence, nor the clinical experience of skilled clinicians.
For example, consider the following:
Disc Pathology
In individuals without disc pathology, nucleus pulposus migration appears to follow a consistent pattern. Flexion creates a posterior displacement of the nucleus while extension stimulates anterior migration (Alexander et al., 2007; Beattie et al., 1994; Fazey et al., 2006; Fredericson et al., 2001; S.-U. Lee et al., 2009; Zou et al., 2009).
In theory, these findings would support the use of repeated lumbar extension for all disc pain patients.
When pathology is present, however, nuclear migration follows a less consistent pattern.
Cadaveric (Fennell et al., 1996; Scannell & McGill, 2009) models and dynamic MRI studies (Beattie et al., 1994) indicate that in degenerated discs, faults or fissures result in abnormal and less predictable motion of the nucleus (Kolber & Hanney, 2009).
In fact, as the degree of degeneration increases, so does the likelihood that patients may demonstrate increased posterior disc bulging in response to lumbar extension, while flexion can stimulate anterior nuclear migration and bulge reduction (S. U. Lee & Fredericson, 2001; S.-U. Lee et al., 2009; Shacklock, 2002; Zamani et al., 1998; Zou et al., 2009).
Thus, the directional preferences for disc injuries may vary considerably depending on the unique complexities of each individual patient.
Spondylolisthesis and Stenosis
Literature on directional based interventions for spondylolisthesis has been equivocal, with some randomized controlled trials favoring flexion (Gramse et al., 1980; Sinaki et al., 1989) and some favoring extension (Spratt et al., 1993).
The discrepancy may be a consequence of the inherent variability evident in vertebral displacement in spondylolisthesis pathology.
In a study by Oh et al., 41 subjects with Grade I and Grade II spondylolisthesis were examined. 70% of these subjects demonstrated no instability. Of those who did demonstrate instability, half showed displacement with flexion and half showed displacement with extension (Oh et al., 2012).
These results indicate that in back pain patients with symptomatic spondylolisthesis, approximately 50% may respond favorably to extension directionality.
Along with spondylolisthesis, lumbar stenosis is also traditionally believed to respond best to lumbar flexion. In a case study by Padmanabhan et al, however, authors report on a patient who was prescribed repeated lumbar flexion activities due to severe spondylolisthesis and stenosis evidenced on imaging. After 2 years of non-responsiveness to flexion based treatment, the patient demonstrated significant resolution of symptoms following an extension based program (Padmanabhan et al., 2011).
These findings highlight the fact that directional preference cannot be assumed via structural pathology and must be confirmed via physical testing.
Lateral Derangements
In some patients with lumbar pathology, neither flexion nor extension are capable of reducing symptoms. In these cases, frontal or transverse plane forces may be necessary to facilitate medial migration of nucleus pulposus material (Fazey et al., 2006).
For example, Santolin reports on a case study of a patient who exhibited discogenic pain with repeated flexion and repeated extension. This patient was able to reduce symptoms only in response to repeated side glide maneuvers (Santolin, 2003)
Patients requiring non-sagittal directional movements would be impossible to detect via standard imaging.
What If Imaging Reveals Multiple Competing Pathologies?
It is not uncommon for back pain patients to exhibit multiple forms of pathology including simultaneous disc herniations, spondylolisthesis, and stenosis. In this case, what direction should be chosen? It is impossible to differentiate on an image which pathoanatomic feature is most responsible for patient signs and symptoms.
The Importance of a Comprehensive Physical Examination
Given the inadequacy for pathonanatomic structural features to guide treatment selection, a comprehensive and skilled physical examination is necessary. Only through a systematic process of testing and retesting can an individual’s unique treatment needs be identified.
This physical examination should consist of objective measures of dermatomal sensation, myotomal strength, and range of motion (ROM). If these measures improve in response to lumbar extension or lumbar flexion (or lateral forces), a directional preference can be effectively confirmed.
In the absence of changes in these objective metrics, patient-reported changes in pain can help to guide decision-making, however these subjective reports of pain must be interpreted with caution.
Experienced clinicians have encountered the relatively common finding of improved dermatomes/myotomes/ROM following spinal movement in the direction that increases patients’ self-reported pain. Moreover, clinicians commonly witness worsening of dermatomes/myotomes/ROM following spinal movement in the direction that patients subjectively report feels better.
There are two likely explanations for these occurrences. The first possibility is that the patient is experiencing a phenomenon referred to as “centralization” in which the pain is moving in a distal-to-proximal direction. The patient may report an increase in lumbar pain following the direction that produces centralization and thus may declare a subjective preference for the opposite direction. Misclassification of directional preference resulting from centralization can be problematic when considering that a strong body of evidence indicates centralization predicts a favorable prognosis in response to directional based treatment (May & Aina, 2012; Skytte et al., 2005; Werneke & Hart, 2001).
A second possible explanation for this commonly occurring discrepancy may be that patients report discomfort during certain directions of spine movement due to end-range strain on connective tissues caused by hypomobility restrictions. This type of pain is not considered to be harmful and may even be favorable as it reflects the patient’s ability to reach chronically restricted ranges of motion.
For these reasons, objective changes in dermatomes/myotomes/ROM following spine movement are the preferred method for confirming a directional preference. In the absence of changes in these objective findings, changes in pain can be used as an acceptable consideration.
Conclusion
Imaging can be necessary to rule in or rule out red flag pathologies (non-MSK conditions, cauda equina syndrome, myelopathy, or other forms of upper motor neuron disorders) but should never be used to determine rehabilitation treatment selection.
Treatment plan determination must always be constructed using a comprehensive physical examination of testing and retesting physical measures in response to different spinal movements or various stimuli.
The irreplaceable role of the physical examination in confirming a patient’s optimal treatment classification highlights the critical need for skilled Doctors of Physical Therapy in the customization of individualized treatment protocols based on the objective examination findings of each individual patient’s unique presentation.
References
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