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A hip fracture is a fracture in the proximal end of the femur (the long bone running through the thigh), near the hip joint.

The term "hip fracture" sometimes includes the complex consequences of osteoporosis; in the vast majority of cases, a hip fracture is a fragility fracture due to a fall or minor trauma in someone with weakened osteoporotic bone. Most at risk are caucasian, post-menopausal women. Most hip fractures outside of this group are the result of high-trauma injuries such as car accidents.

The death rate for a hip fracture is between 20% and 35% in the first year. *

Synonyms

Most of the synonyms actually describe different types of hip fracture. All of these variations are important because each are treated differently.
  • Fractured Neck of Femur (sometimes Neck of Femur Fracture or NOF) denotes a fracture adjacent to the femoral head. This acronym (NOF) is sometimes loosely used for Hip Fracture.
  • Intertrochanteric or pertrochanteric fracture denotes a fracture which is a few centimeters lower and involves the Greater trochanter
  • Fractured Head of Femur or Head Splitting Fracture denotes a fracture involving the head itself. This is rarer and usually the result of high energy trauma and a dislocation of the hip joint.
  • Subtrochanteric fracture involves the shaft of the femur immediately below the Greater Trochanter and may extend down the shaft of the femur.

Incidence

Approximately 320,000 hospitalizations occur each year due to hip fractures in the USA, with similar proportions in other Western countries.

Pathogenesis/risk factors

Most hip fractures occur as a result of falls in elderly patients. For the thigh bone to break in these circumstances means it must be weaker than normal as similar or worse falls in young people do not usually cause the "hip fracture" pattern of injury. The commonest causes of weakness in bones are
  • Osteoporosis Hip fractures are one of the most serious consequences of osteoporosis; in fact a measure of success or failure of treatment of osteoporosis is the proportion of patients who sustain a hip fracture.
  • Other metabolic bone diseases such as Paget's disease, osteomalacia, osteopetrosis and osteogenesis imperfecta. Stress fractures may occur in the hip region with metabolic bone disease.
  • Benign or malignant primary bone tumours are rare causes of hip fracture
  • Metastatic cancer deposits in the proximal femur may weaken the bone and cause a pathological hip fracture
  • Infection in the bone is a rare cause of hip fracture.

The other major element in the risk of sustaining a hip fracture is the risk of falling. Falls Prevention is an important subject with concerns in the area of providing a safe environment for people at risk, custodial care, walking aids, medication issues etc. Hip Protectors are padded plastic shields that can be placed over the trochanters of people at risk of falling or of sustaining a fragility fracture. They are effective in reducing the likelihood of a hip fracture but it is a challenge to get people to wear them.

Classification (types of fracture)

There are two main types of fracture pattern - intertrochanteric fracture, and fractured neck of femur. The difference is important because the treatment and prognosis are different.

Fractured neck of femur

Fractured neck of femur involves the narrow neck between the round head of the femur and the straighter shaft. This fracture often disrupts the blood supply of the head of the femur - the part that makes up the hip joint.

Garden classified this fracture into four types:

  • Type 1 is a crack in the femoral neck with no displacement.
  • Type 2 is a break across the neck with impaction of the fracture but no displacement.
  • Type 3 involves displacement of the fracture (often rotation and angulation) but still some contact between the two fragments.
  • In type 4 there is complete displacement and no contact between the fracture fragments. The blood supply of the femoral head is much more likely to be disrupted in Garden types 3 or 4 fractures.

Surgeons may treat these types of fracture by replacing the bone with a metal prosthetic component cemented into the bone to replace the femoral head. Alternatively the treatment is to reduce the fracture (manipulate the fragments back into a good position) and fix them in place with metal screws or a screw-and-plate device. It has not yet been scientifically established whether one treatment is superior to the other.

Displacement and failure to heal can be problems when the fracture is fixed. Pauwels showed that if the angle of the fracture is too steep the injury is at risk of nonunion or malunion. Another serious complication of a fractured neck of femur is avascular necrosis. The fracture interrupts the blood supply to the head and the bone tissue of the head dies. Unless new living cells migrate into the dead area the femoral head will collapse causing pain and loss of function.

Intertrochanteric fracture

Intertrochanteric fractures occur slightly further down the bone and the fracture line crosses the Inter-trochanteric line between the two trochanters at the upper end of the femur. Because the fracture is lower the blood supply of both fragments is usually intact. This improves the chance of healing and reduces the likelihood of avascular necrosis.

The main concern in the classification of Intertrochanteric Fractures is the stability of the fracture pattern. When the fracture has many fragments (multifragmentary) there is a risk that it will shorten, rotate or angulate before it heals. When the Lesser Trochanter is broken off as a separate fragment the fracture is unstable and likely to collapse.

Natural history

Hip fractures are very dangerous episodes especially for elderly and frail patients. The risk of dying from the stress of the surgery and the injury in the first few days is about 10%. If the condition is untreated the pain and immobility imposed on the patient increase that risk. Problems such as pressure sores and chest infections are all increased by immobility. Eventually the untreated intertrochanteric fracture will heal but with a high likelihood of deformity, shortening of the bone and rotational mal-alignment. Healing of untreated fractured neck of femur is much less certain and displacement even more likely. The untreated prognosis of most hip fractures is very poor.

Clinical features

Symptoms

  • History of a provoking episode such as a fall or an accident.
  • Pain in the hip region
    • Made worse by moving the thigh
    • Usually so severe the patient is unable to walk
    • May radiate to the knee
    • If pain in the hip existed before the fall the patient should be investigated for a Stress fracture or a pathological deposit in the proximal femur.
  • The patient's general medical condition must be carefully assessed. It is often necessary to obtain a consultation from an Internist and/or Anaesthetist.
  • Risk factors for falling should be evaluated. The patient's social situation needs to be considered.

Signs

Signs involving provoking pain should only be elicited when there is doubt about the diagnosis. Usually the diagnosis is obvious and care should be taken to avoid hurting the patient.
  • Tenderness and swelling in the proximal thigh
  • Pain when the leg is moved or rotated
  • Pain on telescoping the limb
  • The affected leg is often shortened and externally rotated
  • Pulses and sensation are not usually changed by a hip fracture but should be checked.

Investigations

X-ray of the affected hip usually makes the diagnosis; AP and shoot-through lateral views should be obtained. In the rare situation where a hip fracture is suspected but does not show on plain Xray a CT scan with 3D reconstruction may be helpful. In cases more than 7 days post injury a bone scan may reveal a cryptic fracture.

As the patients most often require an operation, full pre-operative general investigation is required. This would normally include blood tests, ECG and Chest Xray.

See also

External links

Fractures

Oberschenkelhalsfraktur

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Hip fracture".

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