Low Back Myofascial Pain Disorders

While there are many different muscles in the abdomen, mid to low back, and pelvis that will refer pain into the low back and upper buttocks area, the two most common sources of low back pain are active myofascial trigger points (TrPs) in the quadratus lumborum (QL) and gluteus minimus (GMn) muscles. TrPs in these muscles frequently result in well-defined patterns of pain referral codeine phosphate 30mg that may be variously experienced as “lumbago” or “sciatica” pain.
Quadratus Lumborum

Low back pain centered in the lumbar region, commonly called “lumbago”, is more often of muscular origin than is generally realized. The quadratus lumborum (QL) is the most frequent muscular cause of low back pain and may account for over 30% of musculoskeletal pain complaints seen by osteopathic and physiotherapy practitioners. Through satellite TrPs in the gluteus minimus, the QL may also be responsible for “pseudo-disc syndrome” and “failed surgical back syndrome”.

Referred pain from TrPs in the QL muscle is projected posteriorly to the region of the sacroiliac (SI) joint and the lower buttock, sometimes anteriorly along the crest of the ilium to the adjacent lower quadrant of the abdomen and the groin, and to the greater trochanter. Severe referred tenderness of the greater trochanter may disrupt sleep. The pattern of referred pain produced by active myofascial TrPs in the quadratus lumborum is illustrated in Figure 1a & 1b below.

Patients generally seek relief by lying supine or on the side. They find that the angle of forward or backward tilt of the hips with regard to the lumbar spine is critical. In severe cases, only creeping on all fours may provide a means of locomotion. Sitting is often made more tolerable by unloading some of the weight of the upper body by pressing the arms down on the armrests of the chair.

TrPs in the QL are frequently activated by sudden trauma, as in a motor vehicle accident, or by awkward lifting of a heavy load. A quick stooping movement when the torso is twisted or turned to the side may result in QL pain. QL TrPs can also be activated by sustained or repetitive strain from activities such as gardening, scrubbing floors, lifting cement blocks, or by walking or jogging on a slanted surface.

Figure 1. A) Consolidated referred pain pattern of the two superficial TrP locations (Xs) for the quadratus lumborum muscle. B) Consolidated referred pain pattern of the two deep TrP locations (Xs) for the quadratus lumborum muscle.
The gluteus medius and gluteus minimus muscles commonly develop satellite TrPs as a result of the stresses placed on these muscles by changed posture and movement patterns resulting from QL pain. Conversely, TrPs can develop in the QL as a consequence of TrPs in other muscles. For example, the QL is subject to overload when used to substitute for weak hip abductors in walking. Active TrPs in the gluteus medius and gluteus minimus are one of many causes of such hip weakness.

Gluteus Minimus

Often referred to as “pseudo-sciatica”, pain from TrPs in the gluteus minimus (GMn) muscle can be intolerably persistent and excruciatingly severe. The TrP source of the pain is so deep in the gluteal musculature and much of the pain is so remote from the muscle that its true origin is easily overlooked.

The referred pain from the GMn broadly follows a sciatica-like pattern. TrPs in the anterior part of the GMn muscle refer pain over the lower lateral aspect of the thigh, knee, and leg to the ankle. TrPs in the posterior portion of the GMn have a similar but more posterior pattern that projects pain over the medial aspect of the buttock, and down the back of the thigh and calf. These characteristic pain patterns are shown below in Figure 2a & 2b.

Figure 2. A) Referred pain patterns and locations (Xs) of TrPs in the anterior portion of right gluteus minimus. B) Referred pain patterns and locations (Xs) of TrPs in the posterior portion of right gluteus minimus.
The primary function of the GMn is as an abductor of the thigh; helping to keep the pelvis level during single-limb weight-bearing.

The majority of persons with symptoms of “sciatica” do not have sciatic nerve pain or radiculopathy but instead have pain of ligamentous or muscular origin. The GMn is a potent myofascial source of symptoms that may be mistaken for an L4, L5 or S1 radiculopathy. Sensory or motor deficits and parathesias in a nerve-distribution pattern, imaging of the spine, and electrodiagnostic tests distinguish neurogenic from TrP-referred pain. The latter is recognized by locating the TrPs and identifying their associated phenomena.

GMn TrPs may be activated by an acute overload imposed by a fall; by walking too far or too fast, especially on rough ground; or by overuse in running and sports activities, such as tennis and handball. Temporary distortion of normal gait by a foot or leg injury can also activate GMn TrPs. Prolonged immobilization of the hip, such as occurs when driving long distances with the right foot fixed on the accelerator, can aggravate GMn TrPs. Similarly, prolonged standing, as when waiting in a line-up, or standing at a cocktail party can activate GMn TrPs. Even sitting on a fat wallet can cause problems.

Injections of medications into the buttocks— if into the GMn— will frequently cause activation of TrPs. Similarly, lumbar laminectomy surgery may activate GMn TrPs which then result in continuing pain… “post-lumbar laminectomy syndrome”.

Other Muscles

Other muscles that are commonly involved in lower back pain are the iliopsoas muscle, gluteus medius muscle, piriformis muscle, and rectus abdominis muscle.

The iliopsoas muscle is a “hidden prankster” in the sense that it serves many critically important functions, often causes pain, and is relatively inaccessible. Unidentified iliopsoas and/or quadratus lumborum TrPs are frequently responsible for a failed low back postsurgical syndrome. Referred pain from the iliopsoas extends along the spine ipsilaterally from the mid-back down to the sacroiliac area, and sometimes into the upper buttock. Pain may also be referred to the anterior upper thigh and groin area. Pain is aggravated by weight-bearing activities and relieved by recumbency.

Referred pain from the gluteus medius muscle is frequently identified as lumbago and most often encompasses the posterior crest of the ilium, the sacrum, and the upper portion of the buttock. Patients usually experience pain when walking, when lying on the back or on the affected side, and when sitting slouched down in a chair.

Referred pain from the piriformis and other short lateral rotators of the hip may radiate into the sacroiliac region, laterally across the buttock and over the hip region posteriorly, and to the proximal two-thirds of the posterior thigh. Pain is increased by sitting, standing, and walking.

Active TrPs in the abdominal muscles, particularly the lower end of the rectus abdominis, will radiate pain in a broad, belt-like band across the lower back at the sacrum.