Low back pain is one of the most common conditions impacting people around the world. Surveys indicate that at least 40-60% of adults have experienced low back pain during their life, with some estimates placing the prevalence as high as 85%. Of those who suffer from low back pain, about 1 in every 7 will have back pain for at least 2 weeks. There are numerous possible causes of this pain, and factors as varied as smoking, obesity, older age, female gender, physically strenuous work, sedentary work, job dissatisfaction, and depression can increase an individual’s risk. Low back pain can be debilitating, significantly diminishing the quality of life and functionality of those affected. This puts a significant burden, both personal and financial, on millions of people. Although it can be difficult to make a specific diagnosis or determine the exact etiology of low back pain, appropriate treatment requires a definite pathology. One common, but often overlooked, pathology is sacroiliac joint pain.
There is no singular pain pattern associated with the sacroiliac joint, but there are several common symptoms. There is most often pain in the low back and one or both buttocks. This will sometimes radiate to the hip, posterior thigh, or iliac spine. There may be concurrent numbness, popping, clicking, and groin pain. Because of the relationship with the overlying musculature and nerves, sacroiliac joint pain can also present with symptoms of sciatica. This is often characterized by a burning pain, a pins and needles sensation, numbness and tingling, with or without weakness traveling down the leg past the knee, often posterior.
The origin of sacroiliac joint pain is ultimately a biomechanical failure or joint dysfunction causing irritation to the joint capsule or the adjacent tissues.
Postural habits, recreational activities, and professional activities can predispose individuals to biochemical stresses on the sacroiliac joints. For instance, athletes that are involved in sports that require unilateral loading of the pelvis, such as repeated kicking or throwing, are at increased risk of developing sacroiliac joint pain. Additionally, participating in sports that generate lateral and anterior-posterior shearing forces on the pelvis, like cross country skiing and rowing, can put athletes at increased risk for sacroiliac pain. Sedentary individuals and those who have frequent strenuous axial loads (like a waiter carrying a tray, or construction worker carrying heavy objects) are also at increased risk of stress on the joints.
Joint Dysfunction – Restriction and Instability
Restricted sacroiliac joint mobility can stem from inflammatory conditions, such as ankylosing spondylitis which can lead to fusion of the sacra and ilia. It can also stem from para-articular osteophytes (bone spurs), which impinge on the limited range of motion of the joint. Finally, persistent immobility may contribute to narrowing or obliteration of the sacroiliac joints, fusing the joint from any movement. Joint instability comes from increased laxity, either caused by an acute injury with tearing of the ligaments or joint capsule or due to physiologic changes or genetic hyper-mobile conditions. Even a simple fall can cause direct injury to the articular cartilage lining the joint and the adjacent stabilizing ligaments resulting in an unstable joint and acute pain. In the case of special populations, joint instability stems from ligamentous laxity caused by physiologic changes, such as the release of the hormone relaxin in pregnant women. Others have inherited ligamentous laxity, such as Ehlers-Danlos syndrome, or other generalized hypermobility conditions.
A detailed and thorough examination by a specialized practitioner is the mainstay of diagnosis for sacroiliac joint pain and dysfunction. There are a number of maneuvers in the clinician’s armamentarium that stress the sacroiliac joints that can be used during the physical exam to compress or distract the joint.
Imaging is not always necessary in diagnosing sacroiliac joint pain and dysfunction. It is most useful in ruling out other sources of low back pain. The first step will often be x-ray, which may illustrate joint space compromise or bony irregularities suggestive of arthritis, sacral fractures, or adjacent bony structures. Bedside ultrasound can also be used to assess real time instability of the joint with movement during dynamic testing. If pain is persistent or refractory to conservative treatment (often 6 weeks of management with physical therapy and/or other means), advanced imaging may be necessary. In this case, MRI is the modality of choice as it can show soft tissue and bony inflammation with a high level of detail.
The natural history of sacroiliac joint pain is characterized by an acute phase, recovery phase, and chronic phase. The acute phase typically lasts 1-5 days, during which pain is exacerbated by some trauma or biomechanical stress. The recovery phase follows, lasting up to 8 weeks and often leading to resolution of symptoms with appropriate treatment. Unfortunately, some individuals will develop chronic pain, lasting beyond that anticipated 8 week mark. There is a general consensus that conservative therapy during the acute and recovery phase is the most appropriate course of treatment resulting in desirable outcomes.
Acute Phase: Icing, rest, and progressive mobilization as tolerated
Recovery phase: Mobilization, physical therapy, and exercise focused on lumbosacral and lumbo-pelvic stabilization. In cases of joint laxity, a sacroiliac joint belt may improve stability.
Fluoroscopic or ultrasound guided intra-articular injections can be both diagnostic and therapeutic. A mixture of local anesthetic and corticosteroid is injected, resulting in immediate pain relief and reduction in inflammation. Ultrasound-guided injections can be performed without the need for radiation, hospital setting, or contrast material.
In certain patients, hyperosmolar dextrose, or prolotherapy, as well as PRP, can improve pain in the long term, particularly when related to ligamentous injury.
Early research also suggests intra-articular viscosupplementation, such as hyaluronic acid injections, may be promising in some cases of sacroiliac joint pain.
Surgical – Last Resort
Surgical arthrodesis involves fixation or fusion of the sacroiliac joint. This is an intervention of last resort, and should be reserved for cases of sacroiliac joint infection, severe instability, or displaced fracture. There is no guarantee that surgical intervention will result in complete pain relief, and it should only be pursued by certain patient populations and were more conservative measures have absolutely failed.
By Anthony Kenrick, MD and Mo Mortazavi, MD
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