Lonkkaluu

Lonkkaluu, the Finnish term for the hip bone, is one half of the pelvic girdle in humans. Each lonkkaluu is formed by the fusion of three bones—the ilium, ischium, and pubis—that come together during adolescence to create a single os coxae, or hip bone. The pair of hip bones, along with the sacrum, constitute the pelvic ring.

The hip bone consists of distinct regions. The ilium forms the upper, wing-like part and contains the iliac crest and the acetabulum, the socket that receives the femoral head. The ischium makes up the lower posterior portion and includes the ischial tuberosity, while the pubis forms the anterior portion and contributes to the obturator foramen. The acetabulum is the major articulation with the femur, forming the hip joint, and the sacroiliac joint links each hip bone to the sacrum posteriorly. The two hip bones join at the pubic symphysis in front.

Functionally, the hip bone supports body weight, transmits loads from the spine to the lower limbs, and provides attachment points for a wide array of muscles and ligaments involved in locomotion and posture. Developmentally, the three constituent bones fuse in late adolescence, and pelvic shape can vary between individuals and sexes, reflecting obstetric and biomechanical factors.

Clinical relevance includes injuries such as pelvic fractures and acetabular fractures, as well as degenerative conditions affecting the hip joint. Understanding the hip bone is fundamental to discussions of human locomotion, anatomy, and orthopedic care.