Disordered Sacroiliac Joint Pain
The disordered sacroiliac joint is hypermobile due to abnormal laxity of damaged ligaments that tether together the bones that form the joint.1-5 The ligament that seems to be most commonly injured is the iliolumbar ligament.3 Damaged ligaments allow the disordered sacroiliac joint bones to partially dislodge when physically stressed. In the upright body, this joint usually bears over 100 pounds or more. It is critical that this disorder be recognized because it is not only a common cause of chronic back pain and sciatica, it may be associated or possibly even causative of a number of common musculo-skeletal conditions (see Table 1). The most common manifestation is chronic low back pain and it may be the cause of between 10 and 30% of such cases.
Some common causes of disorder of the sacroiliac joint are mundane motor vehicle accidents, mechanical falls, and lifting injuries involving torsion of the lower spine.4 Nurses and nursing aides who lift patients are particularly prone to accidental sacroiliac joint injury leading to permanent sacroiliac joint ligament injury and hypermobility. People who work on and fall from ladders and who do lifting and pulling in construction are also prone to accidental and permanent injury of the sacroiliac joint. Sacroiliac joint ligament injury and subsequent laxity is a unifying etiology that explains how these mundane accidental injuries can result in a biomechanical disorder.
Another mundane cause of sacroiliac joint hypermobility is the hormones of pregnancy, which enable the pelvic ring to be more expandable to allow the fetus greater ease of passage during birth. Many women experience chronic low back pain after childbirth due to sacroiliac joint laxity caused by the hormones of pregnancy. After parturition, the sacroiliac joints normally revert to a tightened and locked position. In about one out of five women, full tightening does not occur and these women develop varying intensities of chronic low back pain.
Another symptom experienced by 10-15% of women with sacroiliac joint partial displacement is urinary urgency/ frequency.4 These women have to go more often than most others. These symptoms arise from disruption of function of nerves that control the urinary bladder. Anatomically, these nerves course over the anterior sacroiliac joint in the posterior pelvis, where they form a plexus. When an injured sacroiliac joint is hypermobile, these nerves are jarred and tugged. This jarring effect irritates nerves, causing them to fire and to stimulate the bladder.
How a Hypermobile Sacroiliac Joint Causes Symptoms
A curved spine (scoliosis) represents the unconscious proprioceptive functions of the nervous system, and the muscles and tendons it controls, to swing body mass towards a medial center of gravity. This is necessary wisdom of the human body.
Cantilevering of the head is another unconscious brain-driven proprioceptive attempt to provide a counter-weight to tilted upper-body mass. A head weighs about 12 pounds and each arm about 20 pounds.3 The upper body above an unstable sacroiliac joint can weigh 100 pounds or more. The muscles of the upper body are charged with keeping all of these weights upright and symmetrical about the central axis of the spine. A normal body distributes weight evenly from side-to-side. A body with an unstable sacroiliac joint cannot because the spinal column totters upon an unstable foundation.
Asymmetric shoulders are common in “fibromyalgia” and neck-shoulder patients and further reflect an unbalanced spine. Sacral slippage occurring in one of the sacroiliac joints causes this asymmetry. The tipped shoulder girdle results from a curved spinal column stationed upon a rocky and unstable pelvis—all the while attempting to maintain a medial center of gravity of the upper body mass. Even the arms, which unconsciously splint and raise (flex at the elbow) to accommodate tilted shoulders, develop pain at the elbows (tennis elbow a.k.a. lateral epicondylitis) where arm muscles attach.
An upright body is a complex symphony of momentary and ever-shifting movements and adjustments—all finely tuned to maintain a centrally balanced spine and a body mass symmetrically hung on each side of the spine which functions as an upright support or post. When body mass is chronically off center, the spinal column and muscles of balance are chronically stressed, spastic, and full of pain, i.e., the biomechanical phenomenon that gives rise to upper body pain disorders and fibromyalgia symptoms.
Diagnosis of a Biomechanical Disorder
Over 40 years of practice, I have developed a step-wise protocol to diagnose a biomechanical disorder and I pass this on.