A hip fracture is a bony injury of the proximal femur typically occurring in the elderly.
Older patients are more likely to have gait unsteadiness and reduced bone mineral density, predisposing to fracture.
It is a common serious injury in older people, costing the NHS and social care £1 billion per year.
Risk factors include:
The proximal femur consists of a head, neck, trochanters (greater and lesser) & shaft. It is the largest bone in the human body.
The inter-trochanteric line lies on the anterior surface of the femoral neck, running between the trochanters. It demarcates the inferior attachments of the hip capsule.
The capsule of the hip is attached proximally to margins of acetabulum and transverse acetabular ligament. Distally, to the inter-trochanteric line, bases of greater & lesser trochanters and to the femoral neck posteriorly (approx. 1/2 inch from the trochanteric crest). It contains the retinacular vessels - a major component of the blood supply to the femoral head.
The femoral head receives blood from three sources:
Hip fractures may be categorised as either intra- or extra-capsular, depending on their location in relation to the inter-trochanteric line.
The type of fracture determines the likelihood of disruption to the blood supply of the femoral head. Broadly speaking, intra-capsular fractures are associated with a higher-risk of disruption, owing to the close proximity of the retinacular vessels.
Intra-capsular fractures are further sub-classified according to Garden’s classification.
There are four types.
With type 1 & 2 there is minimal displacement, and therefore a lessened risk of disruption to the femoral head blood supply. Conversely, with type 3 & 4, where there is much greater displacement, there is substantially higher risk.
Classification is based on the integrity of the trabecular lines in an AP projection. It is used to guide management.
In the elderly, hip fractures are normally caused by falls.
The mechanism varies from direct falls onto the affected hip, to twisting, in which the patient’s foot is planted and the body rotates. Bones are typically osteopaenic (reduced bone density) and also deficient in elastic reserve (i.e. they are very brittle).
In younger patients, hip fractures are more commonly the result of major trauma (e.g. motor vehicle accidents), or in patients with gait disturbance (e.g. in multiple sclerosis) in which they are at increased risk of falls. Certain medications, such a prolonged corticosteroid use, can also predispose to osteopaenia.
Hip fractures are diagnosed radiologically, but may be suspected clinically.
Patients usually describe a fall or recent trauma; it is unusual for fractures to occur with no precipitating trauma. High-energy trauma (e.g. motor vehicle accident) is more common in younger patients, although accounts for only a small percentage (2-3%) of all hip fractures.
It is important to elucidate why an individual may have fallen; whether the fall was mechanical in nature (e.g. slipped on a wet floor) or if the event was precipitated (e.g. MI, stroke, chest infection, UTI etc.)
Patients typically report an inability to bear weight and pain in the affected side, with a reduced range of movement.
A hip fracture is a radiological diagnosis, although additional investigations can be used to aid the diagnosis and look for complicating pathology.
Shenton’s line - an imaginary curved line drawn along the inferior border of the superior ramus, along the inferomedial border of the proximal femur. It should be continuous and smooth.
Most hip fractures are treated surgically, unless there are significant co-morbidities restricting surgical intervention. Surgical management differs between intra- and extra- capsular fractures.
In rare cases, conservative treatment can involve traction, bed rest or restricted mobilisation. Outcomes are often very poor in these patients.
NICE guidelines recommend surgery to be performed on the day of, or the day after, admission. The aim is to allow patients to fully weight bear (without restriction) in the immediate postoperative period; however, this often is not possible.
Surgical management is generally as follows:
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