The pear-shaped muscle starts in front of the 2nd, 3rd, and 4th sacral vertebrae, is distributed on the inner surface of the small pelvis, enters the hip through the foramen magnum, and ends at the greater trochanter of the femur. This muscle is susceptible to injury and inflammatory changes due to acute or chronic injury, or anatomical variation, which can irritate or compress the nerve and produce low back pain, called pear-shaped muscle syndrome. It is a syndrome in which the sciatic nerve is compressed in the buttock, and is most common in chronic injury to the nerves of the lower extremities. It is noteworthy because it is easily confused with sciatica caused by lumbar disc herniation. Symptoms and signs Pear-shaped muscle syndrome is mainly manifested by sciatica, with pain radiating from the buttock to the calf and foot through the back of the thigh. Sometimes cords (fibrous scar or striated muscle) can be found in the buttocks (near the ring jump point), and the pear-shaped muscle tension test can aggravate or induce sciatica, and the Tinel sign can be positive at the hip pressure. A history of acetabular fracture may show displaced bone masses or scabs on x-ray. Causes of disease Bleeding, adhesions, scar formation of hip trauma, injection of drugs to degenerate the pear-shaped and fiber contracture, displacement of the upper posterior acetabular fracture, and oversized bone scabs can cause pressure on the sciatic nerve at the pear-shaped muscle.