The Hip Joint
The hip joint is a ball and socket joint formed between the head of the femur (thigh bone) and the hip socket (acetabulum).
The important parts of the hip:
Ball and Socket Joint – The joint between the head of the femur and the acetabulum (socket) of the pelvis.
Joint Capsule – flexible sac around the joint allowing a wide range of movements. The capsule keeps in place the lubricating synovial fluid.
Greater Trochanter – the attachment point for many of the buttock muscles (hip abduction and external rotation)
Lesser Trochanter – the attachment of iliopsoas muscle (hip flexion)
Hip Movements – in the standing position
Flexion – move your leg forwards.
Extension – move your leg backwards.
Abduction – move your leg away from your side.
Adduction – move your leg towards to other leg.
Internal Rotation – rotate your foot towards the other (toes pointing towards each other).
External Rotation – rotate your foot away from the other (toes pointing outwards).
Gluteus Medius is the main hip abductor, and its tendon attaches to the lateral aspect of the greater trochanter.
Gluteus Minimus is a lesser hip abductor and also produces some internal rotation. Its tendon attaches to the upper most part of the greater trochanter.
Tensor Fascia Lata contributes to hip flexion, abduction, and internal rotation in that order. Its tendon blends with the iliotibial band.
There are two main bursae (fluid filled lubricating sacs) in the area – a superficial one lies between the tensor fascia lata muscle and the gluteus medius tendon – the deep one lies between the tendons of gluteus medius and gluteus minimus.
Trochanteric Bursitis – the commonest soft tissue lesion around the hip area.
Causes – overuse – seen in sporting activities involving excessive running, and also in overweight females with degenerative spinal problems.
Clinical Findings – Inflammation of the superficial and deep bursae (fluid filled lubricating sacs) produces well localised pain over the trochanteric region as well as radiating pain down the outside thigh. The pain is aggravated by walking, climbing stairs, lying on the affected side in bed, and may disturb sleep. The pain can be reproduced by stretching the gluteus medius tendon, and by resisted abduction.
Investigations – X-rays show calcification of the bursa in 20% of chronic cases.
Treatment – rest, analgesics, ice, deep tendon massage, LA / Steroid Injections
Anatomy – Iliopsoas is a muscle made up of two parts – Iliacus and Psoas Major. Iliacus originates from the inside of the pelvic bone, whereas psoas major originates from the front of vertebrae L1 to L5. The two muscles then insert via their tendons onto the lesser trochanter of the femur. Iliopsoas is the primary flexor of the hip and is very powerful. A bursa separates the tendon from the front part of the hip joint, another bursa sits behind the insertion point on the lesser trochanter.
Iliopsoas Tendinitis / Bursitis
Causes – overuse – common in athletes
Clinical Findings – Localised tenderness over the insertion on the lesser trochanter. Pain can be reproduced by resisted flexion of the hip. The bursae are so deep that it is rarely possible to feel them as enlarged.
Investigations – hip X-rays are necessary to help differentiate between tendinitis / bursitis and primary hip osteoarthritis. In young people X-rays also help to exclude a slipped femoral epiphysis.
Treatment – Rest, analgesics, hip extension mobilisation techniques (see Hurdler Stretch), and LA / Steroid Injections. The bursa is injected using X-ray guidance so as to avoid the femoral vessels and nerves. It may also be worth injecting the lesser trochanter insertion point at the same time.