“The kinetic chain refers to the fact that joints (and their associated muscles and ligaments) generally can’t be viewed independently. Specifically across a weight bearing like the back or force bearing system like the shoulder, all joints in the chain need to be viewed as a whole.”
Lower back pain is a common clinical problem where understanding the kinetic chain is critical to treatment (Here we are considering the lumbar spine). As will be demonstrated, it is predominately due to altered spine position that occurs because of abnormal hip position (excessively anterior, posterior, or lateral), particularly during gait. The altered spine position is caused by factors below the waist discussed in the next paragraph. Short muscles from prolonged sitting, termed sitting disease, is a major cause in the US. Patients are told, and which they repeat coming into our offices, they have a ‘disc’.
While they may “have a disc”, discs generally remain stable after the age of 40. So while they have discs, the question is why do they have pain (particularly since discs and cartilage have minimal to no nerve endings)? Pain typically originates from strained ligaments/muscles, muscle spasm, and/or a disc that has moved to compress a nerve. This is seen in the second figure (courtesy Elservier Corporation1). An arch in the lumbar spine is favorable. However, an excessive arch due to anterior (forward) tilt of the hip (figure A), here caused by tight hip flexors (sitting disease), is a common cause of back pain. As shown in figure C (showing the L1 and L2 vertebra), from this excessive curvature, damage to the anterior ligaments (green arrow) and narrowing of the nerve space (moving the nerve and a disc in contact) cause pain. Besides tight hip flexors, internal rotation or inversion of the foot will cause anterior tilting of the pelvis (figure 1). The damage is exacerbated with any of these causes by the force of foot impact during gait (walking or running).
The spine can also bend backwards from posterior (backwards) rotation of the hip (figure B). This is commonly do to tight hip extenders (also a form of sitting disease) which is generally the hamstrings. It can also be caused by external rotation or eversion of the foot. When the hip rotates posteriorly, as show in figure D, the posterior ligaments (green arrow) and muscles of the spine become stretched, becoming a source of pain. In addition, the intervertebral disc protrudes in the direction of the spinal cord, potentially causing spinal stenosis. Again, the strain is worse during foot impact.
So while the back is being strained and pain is occurring there, the origins of the problem are not in the back. We have stated since prior to 2000, and the AMA has recently supported, imaging (X-ray or MRI) of the back is overused for managing back pain.
The figure to the left illustrates the principles of the kinetic chain. This patient has back and knee pain, but the primary cause is neither the back nor the knee. The etiology is chronic inversion of the foot (red arrow) which is particularly problematic during gait (walking and running). The inverted ankle causes medial displacement of the knee, making the knee susceptible to medial knee injury. The altered knee position then leads to a lateral drop of the pelvis. The pelvic drop leads to a shift in the spine causing stretch of ligaments on one side. On the other side, muscles spasm and the spinal nerves can become compressed. This is discussed in detail in the next figure.
Issues in the back, knee, hip, neck, shoulder, and arm all need to be analyzed in a
similar way with respect to the kinetic chain.
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1 Neumann, D.A. Kinesiology of the Musculoskeletal System. 2nd Edition Elservier Publishing. 2009, ISBN-10: 9780323039895
Again this videos are intended for educational purposes only and do not replace seeing a health care professional. FOR EXAMPLE, ACUTE AND EVEN CHRONICS BACK PAIN CAN BE TUMOR, FRACTURES, OR INFECTIONS ALL OF WHICH ARE SERIOUS AND NEED TO BE RULED OUT.
Mark Brezinski MD, PhD, CPT
