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Want more information on anatomy before you begin looking at conditions? Head to our articles on Bones of the Lower Limb and Muscles of the Thigh!
The neck of the femur connects the head of the femur to the shaft. Neck of femur fractures can be divided into two categories: intracapsular (inside the capsule, the tough sleeve of tissue around the hip joint) and extracapsular (outside the capsule).
Intracapsular fractures mostly affect older people. Osteoporosis (weak, thin bones) and being female both increase the risk. If an intracapsular fracture is displaced (the broken ends have moved out of line), the patient presents with a shortened and externally rotated leg at the hip.
The medial femoral circumflex artery (a branch of the deep femoral artery that runs round the neck of the femur) is at risk of injury, especially if the fracture is displaced (the broken ends have moved out of line). It is the main artery that supplies the head of the femur, so damage to it can cause avascular necrosis (death of bone tissue because its blood supply is lost) in the femoral head. As a result, surgery is needed quickly. NICE advises operating on the day of admission or the day after, to fix or replace the broken bone and limit permanent damage to the femoral head. For a displaced intracapsular fracture, NICE advises a hip replacement: either a total hip replacement (the whole joint is replaced) or a hemiarthroplasty (only the ball of the joint, the femoral head, is replaced). A total hip replacement is considered for people who could walk independently outdoors with no more than a stick before the fracture, are fit enough for the operation and are expected to manage daily activities independently for more than 2 years.
Extracapsular fractures also mainly affect older people, especially those with osteoporosis. If an extracapsular fracture is displaced, the patient also presents with a shortened and externally rotated leg at the hip due to the distal fragment being pulled upwards and rotated laterally. Avascular necrosis is very rare in extracapsular fractures because the fracture is distal to the medial femoral circumflex artery, so the blood supply remains intact. Extracapsular fractures are usually fixed with a sliding hip screw (a metal screw and plate that hold the bone together) or, for fractures below the trochanters (subtrochanteric), an intramedullary nail (a metal rod placed inside the bone).
Diagram - The two main types of femoral neck fractures
Creative commons source by Doctodoc, edited by Dr. Laura Hansell [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Hip dislocation occurs when the femoral head (the ball of the joint) is no longer in contact with the acetabulum (the socket in the pelvis). It can be divided into two main types: anterior and posterior. A natural hip joint is very stable, with a deep socket and many strong ligaments to support it, so dislocating it needs significant force. A hip replacement (prosthetic joint) is less stable and can dislocate with minor movements.
90% of hip dislocations are posterior (the femoral head sits behind the socket). The most common cause is force through a bent knee, such as the knee hitting the dashboard in a car accident. They present with a flexed, adducted and internally rotated leg at the hip. Posterior dislocations can injure the sciatic nerve (in about 10 to 20% of cases), causing sciatic nerve palsy (weakness or paralysis of the muscles that the nerve supplies).
Anterior dislocations are much less common and the mechanism of injury is usually linked to skiing. They present with a flexed, abducted and externally rotated leg at the hip. A femoral nerve palsy may also be present, but this is relatively uncommon.
A hip dislocation is an emergency. Treatment in both cases is urgent reduction (putting the femoral head back into the socket), usually under sedation or general anaesthesia with strong pain relief (analgesia). Surgery is needed if the hip cannot be reduced this way or if there is a fracture that needs repair. Rehabilitation follows.
Image - An X-ray of a hip dislocation, with the femoral head displaced upwards (superiorly)
Creative commons source by James Heilman, MD [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Osteoarthritis (OA) is a condition in which the protective cartilage on the ends of the bones breaks down, causing pain and stiffness. OA of the hip becomes more common with increasing age and is a frequent cause of pain and disability in older adults. It usually causes pain that comes on with activity (mechanical pain), felt in the hip, buttock and groin and sometimes spreading to the knee. There may also be stiffness, which is usually absent in the morning or lasts 30 minutes or less, and reduced mobility. The exact cause of OA is not known (this is called primary OA), but the risk is higher with older age, obesity, a family history of OA and previous joint injury. OA can also develop after a joint has been damaged by another problem (secondary OA), such as trauma (physical injury), infection, rheumatoid arthritis (an autoimmune condition that inflames joints) or metabolic disorders (for example gout).
The first treatments offered are therapeutic exercise (exercise tailored to the person, such as muscle strengthening and general fitness) and weight loss if the person is overweight, along with information and support. Medicines are added only if needed, alongside these treatments, at the lowest effective dose for the shortest time. If topical medicines (such as anti-inflammatory gels) are ineffective or unsuitable, an oral NSAID (non-steroidal anti-inflammatory drug) can be considered, with a stomach-protecting medicine such as a proton pump inhibitor. NICE does not routinely recommend paracetamol or weak opioids. A hip replacement can be considered when symptoms substantially affect quality of life and non-surgical treatment is ineffective or unsuitable.
Image - Osteoarthritis affecting the hip joint
Creative commons source by CFCF [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Injury to the Superior Gluteal Nerve
Damage to the superior gluteal nerve typically presents with Trendelenburg’s sign. This is dropping of the pelvis on the opposite (contralateral) side to the nerve injury when the patient stands on the leg of the affected side. This occurs because the superior gluteal nerve supplies gluteus medius and gluteus minimus (the two smaller buttock muscles) and tensor fasciae latae (a small muscle at the front and side of the hip). Gluteus medius and minimus abduct the hip (move the leg away from the midline) and keep the pelvis level when standing on one leg. When walking, the patient may compensate by leaning their trunk towards the affected side, which keeps their weight over the leg they are standing on. This abnormal way of walking (gait) is called Trendelenburg gait.
Diagram - A positive and a negative Trendelenburg's sign
Creative commons source by Mikael Häggström [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Reviewed by: Dr. Thomas Burnell and Dr. Marcus Judge
Edited by: Dr. Maddie Swannack
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