A hip fracture is a break that occurs in the upper part of the femur (thigh bone), at the femoral neck or (rarely) the femoral head. Symptoms may include pain around the hip, particularly with movement, and shortening of the leg. Usually the person cannot walk.
A hip fracture is usually a femoral neck fracture. Such fractures most often occur as a result of a fall. (Femoral head fractures are a rare kind of hip fracture that may also be the result of a fall but are more commonly caused by more violent incidents such as traffic accidents.) Risk factors include osteoporosis, taking many medications, alcohol use, and metastatic cancer. Diagnosis is generally by X-rays. Magnetic resonance imaging, a CT scan, or a bone scan may occasionally be required to make the diagnosis.
Pain management may involve opioids or a nerve block. If the person's health allows, surgery is generally recommended within two days. Options for surgery may include a total hip replacement, hemiarthroplasty (half hip replacement) or stabilizing the fracture with screws. Treatment to prevent blood clots following surgery is recommended.
About 15% of women break their hip at some point in life; women are more often affected than men. Hip fractures become more common with age. The risk of death in the year following a fracture is about 20% in older people.
Signs and symptoms
The classic clinical presentation of a hip fracture is an elderly patient who sustained a low-energy fall and now has groin pain and is unable to bear weight. Pain may be referred to the supracondylar knee. On examination, the affected extremity is often shortened and externally rotated compared to the unaffected leg.
Complications Nonunion, failure of the fracture to heal, is common in fractures of the neck of the femur, but much more rare with other types of hip fracture. Avascular necrosis of the femoral head occurs frequently (20%) in intracapsular hip fractures, because the blood supply is interrupted.
Malunion, healing of the fracture in a distorted position, is very common. The thigh muscles tend to pull on the bone fragments, causing them to overlap and reunite incorrectly. Shortening, varus deformity, valgus deformity, and rotational malunion all occur often because the fracture may be unstable and collapse before it heals. This may not be as much of a concern in patients with limited independence and mobility.
Hip fractures rarely result in neurological or vascular injury.
Medical Most people who have a hip fracture are living with frailty. This means they are at increased risk of developing complications after an injury or surgery. Some people also are unwell before breaking a hip. It is common for the break to have been caused by a fall due to some illness, especially in the elderly. Additionally, the stress of the injury, and a likely surgery, increases the risk of medical illness including heart attack, stroke, and chest infection.
Hip fracture patients are at considerable risk for thromboembolism, blood clots that dislodge and travel in the bloodstream. Deep venous thrombosis (DVT) - clots forming in the deep veins of the leg - is very common after hip fracture as the circulation is stagnant and the blood is hypercoagulable as a response to injury. DVT can occur without causing symptoms. A pulmonary embolism (PE) occurs when clotted blood from a DVT comes loose from the leg veins and passes up to the lungs. Circulation to parts of the lungs is cut off which can be very dangerous. Fatal PE may have an incidence of 2% after hip fracture and may contribute to illness and mortality in other cases.
Delirium is extremely common following a hip fracture. It is most common in the first few days after hip fracture. It usually clears completely. There are multiple causes including inflammation as a result of the fracture and surgery, as well as pain, immobility, moving to a strange place, and drugs and medical complications following hip fracture (such as pneumonia and cardiac issues). Delirium after hip fracture is associated with an increased risk of being diagnosed with dementia. There are currently no drug treatments that have been shown to reduce the risk of developing delirium after hip fracture.
Urinary tract infection (UTI) can occur. Patients are immobilized and in bed for many days; they are frequently catheterised, commonly causing infection.
Prolonged immobilization and difficulty moving make it hard to avoid pressure sores on the sacrum and heels of patients with hip fractures. Whenever possible, early mobilization is advocated; otherwise, alternating pressure mattresses should be used.
Risk factors Hip fracture following a fall is likely to be a pathological fracture. The most common causes of weakness in bone are: Osteoporosis. 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. Elevated levels of homocysteine, a toxic 'natural' amino acid. Benign or malignant primary bone tumors are rare causes of hip fractures. 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. Tobacco smoking (associated with osteoporosis).
Mechanism
Functional anatomy
The hip joint is a ball-and-socket joint. The femur connects at the acetabulum of the pelvis and projects laterally before angling medially and inferiorly to form the knee. Although this joint has three degrees of freedom, it is still stable due to the interaction of ligaments and cartilage. The labrum lines the circumference of the acetabulum to provide stability and shock absorption. Articular cartilage covers the concave area of acetabulum, providing more stability and shock absorption. Surrounding the entire joint itself is a capsule secured by the tendon of the psoas muscle and three ligaments. The iliofemoral, or Y, ligament is located anteriorly and serves to prevent hip hyperextension. The pubofemoral ligament is located anteriorly just underneath the iliofemoral ligament and serves primarily to resist abduction, extension, and some external rotation. Finally the ischiofemoral ligament on the posterior side of the capsule resists extension, adduction, and internal rotation. When considering the biomechanics of hip fractures, it is important to examine the mechanical loads the hip experiences during low energy falls.
Biomechanics
The hip joint is unique in that it experiences combined mechanical loads. An axial load along the shaft of the femur results in compressive stress. Bending load at the neck of the femur causes tensile stress along the upper part of the neck and compressive stress along the lower part of the neck. While osteoarthritis and osteoporosis are associated with bone fracture as we age, these diseases are not the cause of the fracture alone. Low energy falls from standing are responsible for the majority of fractures in the elderly, but fall direction is also a key factor. Elderly patients tend to fall to the side instead of forward, and the lateral hip strikes the ground first. During a sideways fall, the chances of hip fracture see a 15-fold and 12-fold increase in elderly males and females, respectively.
Neurological factors Elderly individuals are also predisposed to hip fractures due to many factors that can compromise proprioception and balance, including medications, vertigo, stroke, and peripheral neuropathy.
Diagnosis
Physical examination Displaced fractures of the trochanter or femoral neck will classically cause external rotation and shortening of the leg when the patient is laying supine.
Imaging Typically, radiographs are taken of the hip from the front (AP view), and side (lateral view). Frog leg views are to be avoided, as they may cause severe pain and further displace the fracture. In situations where a hip fracture is suspected but not obvious on x-ray, an MRI is the next test of choice. If an MRI is not available or the patient can not be placed into the scanner a CT may be used as a substitute. MRI sensitivity for radiographically occult fracture is greater than CT. Bone scan is less sensitive, especially immediately after injury and in the elderly.
A case demonstrating a possible order of imaging in initially subtle findings:
As the patients most often require an operation, full pre-operative general investigation is required. This would normally include blood tests, ECG and chest x-ray.
Types
X-rays of the affected hip usually make the diagnosis obvious; AP (anteroposterior) and lateral views should be obtained.
CapsuleAreaClassificationIntracapsularfemoral head AO 31-C1 – 31-C3 Pipkin classificationfemoral neck SubcapitalAO 31-B1 – 31-B3Garden classification, Pauwel's classification Transcervical BasicervicalExtracapsularTrochanteric Intertrochanteric (between the greater and lesser trochanterPage 245 in: ) AO 31-A1 – 31-A2 Evans' classification (1949), Ramadier's classification (1956), Boyd and Griffin's classification (1949), Decoulx & Lavarde's classification (1969), Ender's classification (1970), Tronzo's classification (1973), Evans-Jensen classification (1975), Deburge's classification (1976), Briot's classification (1980) Pertrochanteric (through the trochanters) AO 31-A3Subtrochanteric AO 32 Seinsheimer classification
Trochanteric fractures are subdivided into either intertrochanteric (between the greater and lesser trochanter) or pertrochanteric (through the trochanters) by the Müller AO Classification of fractures. Practically, the difference between these types is minor. The terms are often used synonymously.Page 190 in: Page 365 in: An isolated trochanteric fracture involves one of the trochanters without going through the anatomical axis of the femur, and may occur in young individuals due to forceful muscle contraction.Page 303 in:
Prevention The majority of hip fractures are the result of a fall, particularly in the elderly. Therefore, identifying why the fall occurred, and implementing treatments or changes, is key to reducing the occurrence of hip fractures. Multiple contributing factors are often identified. These can include environmental factors and medical factors (such as postural hypotension or co-existing disabilities from disease such as Stroke or Parkinson's disease which cause visual and/or balance impairments). A recent study has identified a high incidence of undiagnosed cervical spondylotic myelopathy (CSM) amongst patients with a hip fracture. This is relatively unrecognised consequent of CSM.
Additionally, there is some evidence to systems designed to offer protection in the case of a fall. Hip protectors, for example appear to decrease the number of hip fractures among the elderly, but they are often not used.
Management