Of all backaches, this requires a brief but special mention. The pelvis is surrounded by several bones . Where the iliac bone connects with the sacrum is known as the sacroiliac joint.
This joint is fused but has enough flexibility to dislodge itself and become malaligned which it does frequently. Even slight movements can strain the ligaments and the result is either a short period of discomfort or longer lasting and more severe pain. The inner aspect of the joint is associated with a muscle that bends up the thigh at the hip, known as the psoas. Through and around the psoas travel most of the nerves from the lower lumbar and sacrospinal cord. Any inflammation of the sacroiliac joint may cause inflammation in this muscle or these nerves, leading to a variety of symptoms including sciatica. Abdominal discomfort and hip pain, as well as pains and neurological symptoms throughout the legs, buttocks and lower back, are all associated therefore with the sacroiliac joint.
The ligaments of the pelvis are very much under the influence of oestrogen, which will loosen them, especially in preparation for pregnancy. Women are therefore prone to sacroiliac displacement when oestrogen levels are high during the monthly cycle and are more prone to straining the joint as the ligaments tighten during menopause. Certain activities, especially if muscular stretching has not been undertaken beforehand or if heavy weights are lifted without the back being straight, will all entice sacroiliac strain.