The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the pelvic ilium bone, which is connected by a strong ligament. In humans, the sacrum supports the spine and is supported by the ilium on each side. This joint is a strong synovial weight-regulating joint, together with irregular elevations and depression that results in interlocking of two bones. The human body has two sacroiliac joints, one on the left and one on the right, which often matches each other but varies greatly from person to person.
Video Sacroiliac joint
Structure
C-shaped sacroiliac joints or L-shaped joints capable of performing small (2-18 degree, controversial current) motions formed between the auricular surface of the sacrum and the bone of the ilium. The joints are covered by two different types of cartilage; the sacral surface has hyaline cartilage and the iliac surface has fibrocartilage. SIJ stability is maintained primarily through a combination of only very strong intrinsic and extrinsic bone and ligament structures. The joint space is usually 0.5 to 4 mm.
As we age the characteristics of sacroiliac joint changes. The surface of the joint is flat or planar early in life but when we start walking, the surface of the sacroiliac joint develops different angle orientation and flat or flat topography loss. They also develop a high ridge along the iliac surface and depression along the sacred surface. Associated back and depression, along with very strong ligaments, improves the stability of the sacroiliac joints and makes dislocations very rare. The fossae lumbales laterales ("Venus dimple") corresponds to the superficial topography of the sacroiliac joint.
Ligaments
The ligaments of the sacroiliac joints include the following:
- An anterior sacroiliac ligament
- Interosseous sacroiliac ligament
- Posterior sacroiliac ligament
- The sakrotuberous ligament
- Sacrospinous Ligament
The anterior ligaments are not much of a ligament at all and in most cases only a slight thickening of the anterior joint capsule. The anterior ligament is thin and is not also defined as the posterior sacroiliac ligament.
The posterior sacroiliary ligament (SI) can be subdivided into short (intrinsic) and long (extrinsic). The dorsal interosseous ligament is a very strong ligament. They are often stronger than bones, so the pelvis may actually break before the ligament tear. Dorsal sacroiliac ligaments include long and short ligaments. Long dorsal sacroiliac joint ligaments run in a vertically oblique direction while the short (interoseus) runs perpendicular from just behind the articular surface of the sacrum to the ilium and serves to keep the sacroiliac joints from diverting or opening. Sacrotuberous and sacrospinous ligaments (also known as extrinsic sacroiliary ligaments) limit the amount of sacrum flexes.
The ligaments of the sacroiliac joint relax during pregnancy because of the relaxin hormone; This easing, along with associated pubic symphysis, allows the hip joint to widen during labor. Long SI ligaments can be palpated in skinny people for pain and compared from one side of the body to the other; However, the reliability and validity of comparing ligaments for pain has not yet been demonstrated. The interosseal ligament is very short and runs perpendicularly from the iliac surface to the sacrum, they retain the auricular surface from abduction or opening/diversion.
Maps Sacroiliac joint
Function
As with most of the lower extremity joints, one of SI's joint functions is the absorption of shock (depending on the amount of movement available in the sacroiliac joint) for the spine, along with the torque conversion work allowing transverse rotation occurring beneath the limb to be transmitted to the spine. SI joints, like all lower extremity joints, provide a "self-locking" mechanism (where the joint occupies or reaches the most congruent position, also called the close pack position) that helps stability during the push-off phase of walking. The lock of the joint (or rather be close packed) on one side as weight is transferred from one leg to the other, and through the pelvic weight is transmitted from the sacrum to the hip bone.
Sacroiliac joint movement
- Anterior innominate tilt of both pelvic bones on the sacrum (where the left and right moves as a unit)
- The posterior innininate tilt of both pelvic bones on the sacrum (where the left and right moves together as a unit)
- Anterior innominate tilt of an innominate bone while an oblique innominate bone tilts posteriorly to the sacrum (antagonistic innominate tilt) occurring during gait
- The sacral arch (or clinging) The sacral movements occur along with the ilium movement so you have to be careful in describing this as a separate movement.
- Sacral extension (or counter-nutization).
The sacroiliac joint like all spinal joints (except atlanto-axial) is a bicondylar joint, which means that the one-sided motion corresponds to the correlative movement on the other side.
Clinical interests
Inflammation and dysfunction
Sacroiliitis refers to the inflammation of one or both sacroiliac joints, and is one of the causes of unilateral lower back pain. With sacroiliitis, the individual may experience pain in the lower back, buttocks or thighs, depending on the amount of inflammation. A common problem of sacroiliac joints is often called sacroiliac joint dysfunction (also called joint dysfunction SI; SIJD). Sacroiliary joint dysfunction generally refers to pain in the sacroiliac joint region caused by abnormal movements in the sacroiliac joint, either too much motion or too little motion. This usually results in inflammation of the SI joint, or sacroiliitis.
Signs and symptoms
The following are signs and symptoms that may be related to SI joint problem (SIJ):
- SIJ Dysfunction usually causes unilateral lower back pain which is dull.
- Pain is often mild to moderate pain around the spple or posterior iliac spine (PSIS).
- Pain can get worse and sharper when performing activities such as standing from a sitting position or lifting your knees toward your chest as you climb the ladder.
- Pain is usually on one side or the other (unilateral PSIS pain), but pain can sometimes be bilateral.
- When the pain of severe (rare) SIJ dysfunction, there may be pain in the hip, groin, and sometimes in the leg, but rarely the pain spreads below the knee.
- Pain can be referred from SIJ to the buttock or back of the thigh, and rarely to the foot.
- Pain and lower back stiffness, often unilateral, which often increases with long sitting or prolonged walking.
- Pain may occur during intercourse; However, this is not specific to the sacroiliac joint problem alone.
Sacroiliary joint dysfunction was tested using both provocative and nonprovocative maneuvers. Nonprovocative sacroiliac joint examination maneuvers will include the Gillet Test, flexed knee flexion test, long lying supine test, standing flexibility test, and sit flexion test. Lack of evidence that this sacroiliac joint mobility maneuver detects motion abnormalities.
Given the technical limitations inherent in the visible and palpable signs of this sacroiliac joint mobility maneuver, another major category of clinical signs has been described as provocative maneuvers. This maneuver is designed to reproduce or increase pain coming from within the sacroiliac joint. When provocative maneuvers reproduce pain along typical areas raises suspicion for sacroiliac joint dysfunction. However, there is no single reliable test in the diagnosis of sacroiliac joint dysfunction. Weakness, numbness, or loss of associated reflexes may indicate damage to the nervous system.
The current gold standard for the diagnosis of sacroiliac joint dysfunction originating from within the joint is a confirmed sacroiliac joint injury with fluoroscopy or CT-guidance using local anesthetic solutions. Diagnosis is confirmed when the patient reports significant changes in relief from pain and the diagnostic injection is performed on two separate visits. Published studies have used at least 75 percent change in pain relief before response is considered positive and sacroiliac joints are considered a source of pain.
Pregnancy
Hormonal changes from menstruation, pregnancy, and lactation can affect the integrity of ligament support around SIJ, which is why women often find the days leading up to menstruation is when the pain is the worst. During pregnancy, female hormones are released which allow the connective tissue in the body to relax. Relaxation is necessary so that during labor, the female pelvis can stretch enough to allow birth. This stretch results in changes to the SIJ, making it too mobile. Over the years, these changes may eventually lead to rheumatoid arthritis. As expected, the more pregnancies a woman has, the higher the chances are for SI joint problems. During pregnancy, micro tears and small gas pockets can appear inside the joint. [This paragraph requires a quote]
Muscle imbalances, trauma (eg, falling in the buttocks) and hormonal changes can cause SIJ dysfunction. Sacroiliac joint pain may be felt anteriorly, however, care should be taken to distinguish this from hip joint pain.
Women are considered more likely to suffer from sacroiliac pain than men, mainly due to structural and hormonal differences between the sexes, but so far there is no credible evidence that confirms this idea. Female anatomy often allows one less sacral segment to lock with the pelvis, and this can increase instability.
Additional images
See also
- Venus Blossom
- Sacroiliac joint dysfunction
- Surgery for dysfunctional sacroiliacal joints
- Piriformis syndrome
References
External links
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Huijbregts, Peter (2004). "Dysfunkcja stawu krzy? Owo-biodrowego-diagnoza oparta na dowodach naukowych" [Sacroiliac joint dysfunction: evidence-based diagnosis]. Rehabilitacja Medyczna (in Polish). 8 (1): 14-37. Archived from the original in 2016-03-04. - Anatomical drawing: apmalefrontal4-18 in College of Medicine at SUNY Upstate Medical University
Source of the article : Wikipedia
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