The Hip Joint

The hip joint is a ball and socket joint, formed by the head of the Femur (thigh bone) and the acetabulum of the pelvis. The dome-shaped head of the femur forms the ball, which fits snuggly into the concave socket of the acetabulum. The hip joint is a very sturdy joint, due to the tight fitting of the bones and the strong surrounding ligaments and muscles.

Bones of the hip joint

The femur is the longest bone in the body which forms the thigh. The head of the femur is a round dome shaped protusion which fits into the pelvis to enable degrees of movement. The surfaces the femur are covered with a thin layer of hyaline cartilage which acts to allow smooth movement of the joint.

The pelvis is actually two large bones which connect at the front by the pubis symphesis (a cartilage disc) and at the back by the Sacrum. The Sacrum is part of the spine and consists of 4 fused vertebrae which do not move independently of one another. The joints formed by either side of the Sacrum and the two pelvic bones are the Sacroiliac joints (SIJ).

The hip joint capsule

The joint capsule is a thick ligamentous structure with circular and longitudinal fibres that surround the entire joint. Inside this capsule is a specialised membrane known as the synovial membrane which provides nourishment to all the surrounding structures.

Ligaments of the hip joint

The stability of the hip owes greatly to the presence of its ligaments.

Iliofemoral ligament: This is a strong ligament which connects the pelvis to the femur at the front of the joint. It resembles a Y in shape and stabilises the hip by limiting hyperextension
Pubofemoral ligament: The pubofemoral ligament attaches the part of the pelvis known as the pubis (most forward part, either side of the pubic symphesis) to the femur
Ischiofemoral ligament: This is a ligament which reinforces the posterior aspect of the capsule, attaching to the ischium and between the two trochanters of the femur.

Hip Joint