Sacrum is a bone, triangular in shape, fixed at the base of the spine. It makes the upper back portion of the pelvis like a slice in between two pelvic bones. The last lumbar vertebra is connected superiorly with it and the coccyx is present on the lower border of it. When the sacrum is displaced from its position, stress is produced on the autonomic nervous system, leading to chronic pain.

The fracture of healthy sacral region is rare except in cases of severe injury, for instance a fall or injury to the area. Stress fractures or fatigue fractures of the sacrum bone can be developed in patients with osteoporosis or rheumatoid arthritis.

A big volume of stress and twisting is put on the area of spine where the lumbar and sacral spine (L5 – S1) is connected during some activities for example sports and sitting for greater duration. So, injury to this section of spine can cause back pain radiating towards legs typically.

Sacroiliac Joint Dysfunction: It is a condition in which pain is felt on one side of the low back and is radiated towards the leg up to the knee and in some cases up to the ankle or foot. Due to wider and smaller sacral region of women as compared to that of men, young and middle age women are more prone to develop sacroiliac joint dysfunction. It is very difficult to locate or pinpoint the exact root of the pain, but hyper-mobility (extensive movement of joint) or hypo-mobility (restricted movement of joint) is likely the source of pain in the disrupted normal joint movement between the sacrum and ilium.

In short, when sacral region is disrupted from its normal position due to trauma or stress, pain starts and radiates towards the legs.

 

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References

  1. Ilaslan H, Arslan A, Koç ON, Dalkiliç T, Naderi S. Sacroiliac joint dysfunction. Turk Neurosurg 2010;20(3):398-401.
  2. Cibulka MT, Sinacore DR, Cromer GS, Delitto A. Unilateral hip rotation range of motion asymmetry in patients with sacroiliac joint regional pain. Spine (Phila Pa 1976) 1998;23(9):1009-15.