The Hip Joint resembles in structure the Glenohumeral Joint of the shoulder complex. Formed up by the spherical head the Femur (thigh bone) and the Acetabulum (pelvic bone) is considered a ball and socket joint. It is more stable than the shoulder joint because of the deeper socket (Acetabulum) which is even deepened by the Labrum ( cartilaginous rim that surrounds the Acetabulum rim). The hip joint is the first joint in the weight bearing chain and it sacrifices mobility for stability.
Stability of the joint is derived from the structure of the joint, joint capsule covering the surfaces and bulky muscles that crosses the joint.
Both surfaces of the hip joint ( Femoral head and Acetabulum) are covered by a layer of cartilage which allows the surfaces to glide smoothly against each other.
The hip joint area can be a source of localized pain , area of referred pain from the back (either Lumbar spine or Sacroiliac Joint) or it could be the source of referred pain to the knee joint or to the lower back.
Pain in the Hip joint can be caused by Osteoarthrosis, Bursitis (i.e. Trochanteric bursitis), Muscle strain (i.e. Hamstring strain) or nerve entrapment (i.e. Piriformis Syndrome and Meralgya Paresthetica).