Pelvinring

Pelvinring, or the pelvic ring, is the circular bony framework at the base of the spine that forms the pelvis. It consists of the two hip bones (os coxae), each developed from ilium, ischium, and pubis; the sacrum; and the coccyx. The two hip bones connect anteriorly at the pubic symphysis and posteriorly to the sacrum at the sacroiliac joints, creating a closed ring that transfers axial loads from the spine to the lower limbs.

Anatomical boundaries of the ring are defined by the pelvic inlet and outlet, with strong ligaments reinforcing the joints. The sacroiliac joints and the pubic symphysis provide stability while allowing limited mobility to accommodate childbirth and locomotion. The coccyx sits at the bottom of the ring, completing its continuity.

Functionally, the pelvic ring supports visceral organs within the pelvis, protects pelvic neurovascular structures, and transmits body weight from the spine to the femurs. It also provides attachment sites for muscles of the abdomen, back, hips, and thighs, contributing to posture, locomotion, and core stability.

Clinical significance lies in maintaining ring integrity. Pelvic ring injuries are often the result of high-energy trauma and can compromise stability and cause associated bleeding or organ injury. Diagnosis typically uses pelvic radiographs and computed tomography to delineate fracture patterns. Treatment aims to restore stability and alignment, with management tailored to the fracture pattern, displacement, and patient condition, ranging from immobilization to surgical stabilization.

Developmentally, the pelvic ring forms from multiple embryologic bones that fuse during maturation. Variants in anatomy are uncommon but can influence biomechanics or obstetric considerations.