Hip fracture

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Hip fracture
Classification and external resources
Rt NOF.jpg
AP Hip projection demonstrating an Intertrochanteric fracture
ICD-10 S72.0
ICD-9 820
eMedicine emerg/198 sports/48
MeSH D006620

A hip fracture is a femoral fracture[1] that occurs in the proximal end of the femur (the long bone running through the thigh), near the hip.

The term "hip fracture" is commonly used to refer to four different fracture patterns and is often due to 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 hip fractures in people with normal bone are the result of high-energy trauma such as car accidents, or cycling accidents.

In the UK, the mortality following a fractured neck of femur is between 20% and 35% within one year in patients aged 82, ± 7 years, of which 80% were women.[2]

Types of hip fracture[edit]

  • Femoral head fracture denotes a fracture involving the femoral head. This is usually the result of high energy trauma and a dislocation of the hip joint often accompanies this fracture. It may be classified into four Pipkin's degrees.
  • Femoral neck fracture (sometimes Neck of Femur (NOF), subcapital, or intracapsular fracture)
  • Subtrochanteric fracture actually involves the shaft of the femur immediately below the lesser trochanter and may extend down the shaft of the femur.

Signs and symptoms[edit]

The classic clinical presentation of a hip fracture is an elderly patient who sustained a low-energy fall and now has pain and is unable to bear weight. On examination, the affected extremity is often shortened and unnaturally, externally rotated compared to the unaffected leg.

Risk factors[edit]

Hip fracture following a fall is likely to be a pathological fracture. The most common causes of weakness in bone are:

Diagnosis[edit]

X-rays of the affected hip usually make the diagnosis obvious; AP (anteroposterior) and lateral views should be obtained.

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 another useful alternative however substantial drawbacks include decreased sensitivity, early false negative results, and decreased conspicuity of findings due to age related metabolic changes in the elderly.

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.

Femoral neck[edit]

Garden Type 1 Fractured Neck of Femur

Femoral neck fractures involve the narrow neck between the round head of the femur and the shaft. This fracture often disrupts the blood supply to the head of the femur. British orthopaedic surgeon Robert Symon Garden described a classification system for this type of fracture, referred to as the Garden classification and consisting of four grades:[3][4]

  • Type 1 is a stable fracture with impaction in valgus.
  • Type 2 is complete but non-displaced.
  • Type 3 is partially displaced (often externally rotated and angulated) with varus displacement but still has some contact between the two fragments.
  • Type 4 is completely displaced and there is 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 fractured bone with a prosthesis arthroplasty. Alternatively the treatment is to reduce the fracture (manipulate the fragments back into a good position) and fix them in place with metal screws. Common practice is to use repair Garden 1 and 2 fractures with screws, and to replace Garden 3 and 4 fractures with arthroplasty, except in young patients in whom screw repair is attempted first, followed by arthroplasty if necessary.[5] This is done in an effort to conserve the natural joint since prosthetic joints ultimately wear out and have to be replaced. A serious but common complication of a fractured femoral neck is avascular necrosis. The vasculature to the femoral head is easily disturbed during fractures or from swelling inside the joint capsule. This can lead to strangulation of the blood supply to the femoral head and death of the bone and cartilage.

Intertrochanteric[edit]

Intertrochanteric fractures occur between the greater and lesser trochanters. They are usually fixed with a sliding hip screw and plate. Healing is usually good when the patient is healthy.

Mechanism[edit]

X-ray of the hip joint.

Functional Anatomy[edit]

The hip joint, an enarthrodial joint, can be described as 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[edit]

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. In a study conducted in Umea, Sweden, Bergsten et al. discovered that low energy falls from heights of one meter or less were the leading cause of hip fracture in the elderly adult population [6] . Taking into account that falls were the leading cause of hip fracture, Hwang et al. studied how the manner in which a fall occurs affects the chances of hip fracture. In their study, they found three contributing factors, with fall direction being the strongest predictor.[7] During a sideways fall, the chances of hip fracture see a 15-fold and 12-fold increase in elderly males and females, respectively. This is likely due to a mechanical load experienced by bones weakened by osteoporosis.

Case Studies[edit]

Vector image of intertrocanteric hip fracture.

For example, in case studies by Kelly and Kelly, two elderly females experienced a low energy fall with impact occurring to the knee in a flexed position. Compression along the shaft of the femur caused the neck of the femur at the hip to experience a bending load. The stresses experienced at the neck of the femur resulted in a fracture in both cases. Figure 1 shows the forces acting at the hip visually, while Figure 2 displays the kind of hip fracture discussed. Neither one of the women had osteoporosis, but the manner in which the hip joint was mechanically loaded resulted in a hip fracture. For hip fracture prevention, it is important to consider both onset of osteoporosis and mechanical loading during a fall.

Intertrochanteric fracture classification[edit]

EVANS CLASSIFICATION

Type 1 : Fracture line extends upwards and outwards from the lesser trochanter (STABLE)

1A: Undisplaced two fragment fracture
1B: Displaced two fragment fracture
1C: Three Fragment fracture without posterolateral support, owing to displacement of greater trochanter fragment.
1D: Three Fragment fracture without medial support, owing to displacement of lesser trochanter or femoral arch fragment.
1E: Four Fragments fracture without posterolateral and medial support.

Type 2 : Fracture line extends downwards and outwards from the lesser trochanter

Ramadier's classification

  • a: Cervico-trochanteric fractures
  • b: Simple pertrochanteric fractures
  • c: Complex pertrochanteric fractures
  • d: Pertrochanteric fractures with valgus displacement
  • e: Pertrochanteric fractures with an intertrochanteric fracture line
  • f: Trochantero-diaphyseal fractures
  • g: Subtrochanteric fractures

Briot's grading of diaphyseo-trochanteric fractures

A: Evans' reversed obliquity fracture
B: "Basque roof" fractures
C: Boyd's "steeple" fracture
D: Fractures with an additional fracture line ascending to the intertrochanteric line
E: Fractures with additional fracture lines radiating through the greater trochanter

Ender's classification Trochanteric eversion fractures

1: Simple fractures

2: Fractures with a posterior fragment

3: Fractures with lateral and proximal displacement

Trochanteric inversion fractures

4: With a pointed proximal fragment spike

5: With a rounded proximal fragment beak

6: Intertrochanteric fractures

Subtrochanteric fractures

7: and 7a Transverse or reversed obliquity fractures

8: and 8a Spiral fractures

Boyd and Griffin's classification

  • Linear intertrochanteric line fractures
  • Intertrochanteric line fractures with comminution
  • Subtrochanteric fractures
  • Fractures of the trochanteric region and the proximal shaft

Tronzo's classification

  • Type 1: Incomplete fractures
    Type 2: Uncomminuted fractures, with or without displacement; both trochanters fractured
    Type 3: Comminuted fractures, large lesser trochanter fragment; posterior wall exploded; neck beak impacted in shaft
    Type 3 Variant: As above, plus greater trochanter fractured off and separated
    Type 4: Posterior wall exploded, neck spike displaced outside shaft
    Type 5: reverse obliquity fracture, with or without greater trochanter separation

Hip fractures are treated in one of two ways: Traction or orthopedic surgery.

Management[edit]

Most hip fractures are treated by orthopedic surgery, which involves implanting an orthosis. The surgery is a major stress on the patient, particularly in the elderly. Pain is significant, forcing the patient to remain immobilized. Since prolonged immobilization can be more of a health risk than the surgery itself, post-op patients are encouraged to become mobile as soon as possible, often with the assistance of rehabilitation professionals such as occupational therapy and physical therapy (physiotherapy). Skeletal traction pending surgery is not supported by the evidence.[8]

If operative treatment is refused or the risks of surgery are considered to be too high the main emphasis of treatment is on pain relief. Skeletal traction may be considered for long term treatment. Aggressive chest physiotherapy is needed to reduce the risk of pneumonia and skilled rehabilitation and nursing to avoid pressure sores and DVT/pulmonary embolism Most people will be bedbound for several months. Non-operative treatment is no longer an alternative in developed countries with modern health care.[citation needed]

Fractured neck of femur[edit]

Medial fracture in a 92-year-old woman
Fracture treated with cannulated screws

For low-grade fractures (Garden types 1 and 2), standard treatment is fixation of the fracture in situ with screws or a sliding screw/plate device. This treatment can also be offered for displaced fractures after the fracture has been reduced...

In elderly patients with displaced or intracapsular fractures many surgeons prefer to undertake a hemiarthroplasty, replacing the broken part of the bone with a metal implant. The advantage is that the patient can mobilize without having to wait for healing.

Traction is contraindicated in femoral neck fractures due to it affecting blood flow to the head of the femur.[9]

Intertrochanteric fracture[edit]

Intertrochanteric hip fracture in a 17-year-old male
Fracture supported by dynamic hip screw

An intertrochanteric fracture, below the neck of the femur, has a good chance of healing. Treatment involves stabilizing the fracture with a lag screw and plate device to hold the two fragments in position. A large screw is inserted into the femoral head, crossing through the fracture; the plate runs down the shaft of the femur, with smaller screws securing it in place.

The fracture typically takes 3–6 months to heal. As it is only common in elderly, removal of the dynamic hip screw is usually not recommended to avoid unnecessary risk of second operation and the increased risk of re-fracture after implant removal. The most common cause for hip fractures in the elderly is osteoporosis; if this is the case, treatment of the osteoporosis can well reduce the risk of further fracture. Only young patients tend to consider having it removed; the implant may function as a stress riser, increasing the risk of a break if another accident occurs.

Hip replacement[edit]

In some hip fractures, the doctor completely removes the head and neck of the femur, and replaces it with a prosthetic implant.

Rehabilitation[edit]

Hip fractures are a debilitating injury that is primarily seen in elderly people. Rehabilitation has been proven to increase daily functional status (activities of daily living).

Complications[edit]

Nonunion, failure of the fracture to heal, is common (20%) in fractures of the neck of the femur, but much more rare with other types of hip fracture. The rate of nonunion is increased if the fracture is not treated surgically to immobilize the bone fragments.

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.

Avascular necrosis of the femoral head occurs frequently (20%) in fractures of the neck of femur, because the blood supply is interrupted. It is rare after intertrochanteric fractures.

Hip fractures rarely result in neurological or vascular injury.

Surgical[edit]

Deep or superficial wound infection has an approximate incidence of 2%. It is a serious problem as superficial infection may lead to deep infection. This may cause infection of the healing bone and contamination of the implants. It is difficult to eliminate infection in the presence of metal foreign bodies such as implants. Bacteria inside the implants are inaccessible to the body's defence system and to antibiotics. The management is to attempt to suppress the infection with drainage and antibiotics until the bone is healed. Then the implant should be removed, following which the infection may clear up.

Implant failure may occur; the metal screws and plate can break, back out, or cut out superiorly and enter the joint. This occurs either through inaccurate implant placement or if the fixation does not hold in weak and brittle bone. In the event of failure, the surgery may be redone, or changed to a total hip replacement.

Mal-positioning: The fracture can be fixed and subsequently heal in an incorrect position; especially rotation. This may not be a severe problem or may require subsequent osteotomy surgery for correction.

Medical[edit]

Many of patients 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. Nevertheless, the stress of the injury, and a likely surgery, does increase the risk of medical illness including heart attack, stroke, and chest infection.

Blood clots may result. Deep venous thrombosis (DVT) is when the blood in the leg veins clots and causes pain and swelling. This 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 are 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.

Mental confusion is extremely common following a hip fracture. It usually clears completely, but the disorienting experience of pain, immobility, loss of independence, moving to a strange place, surgery, and drugs combine to cause delirium or accentuate pre-existing dementia.

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.

References:[10][11][12]

Prognosis[edit]

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%.[citation needed] 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. The prognosis of untreated hip fractures is very poor.

Post operation[edit]

Among those affected over the age of 65, 40% are transferred directly to long-term care facilities, long-term rehabilition facilities, or nursing homes; most of those affected require some sort of living assistance from family or home-care providers. 50% permanently require walkers, canes, or crutches for mobility; all require some sort of mobility assistance throughout the healing process.

Among those affected over the age of 50, approximately 25% die within the next year due to complications such as blood clots (deep venous thrombosis, pulmonary embolism), infections, and pneumonia.[citation needed]

Patients with hip fractures are at high risk for future fractures including hip, wrist, shoulder, and spine. After treatment of the acute fracture, the risk of future fractures should be addressed. Currently, only 1 in 4 patients after a hip fracture receives treatment and work up for osteoporosis the underlying cause of most of the fractures. Current treatment standards include the starting of a bisphosphonate to reduce future fracture risk by up to 50%.

Prevention[edit]

Preventing hip fractures is a major concern for the elderly because it is an extremely hard rehabilitation process to go through at that age. The most common way that elderly individuals endure hip fractures is by falling and concurrently suffering from osteoporosis.

Many studies have been conducted in order to find the best way to prevent them from happening. Two studies that were conducted in Norway showed that external hip protectors could reduce the number of hip fractures by almost 50%.[13] Another study in Norway wanted to see the effect of hip protectors as a prevention strategy when offered as a regular part of the healthcare for residents in a nursing home. These external hip protectors were placed securely in special undergarments and were made out of stiff polypropylene on the outside and soft plastozote on the inside. The hip protectors diverted a “direct impact away from the greater trochanter during falls from standing heights.[13] If an individual were to fall, the hip protector would transmit released energy to the tissues and muscles surrounding the femoral bone. The study showed that the use of these hip protectors had a 39% reduction rate in the incidence of hip fractures compared to those who did not wear hip protectors.[14]

Primary prevention[edit]

There are many other prevention strategies that do not include wearing hip protectors. Hip fracture prevention strategies can be broken up into components of primary, secondary, and tertiary prevention. Primary prevention is aimed towards populations at high risk. Prevention of bone mineral density would need to start around the time of menopause for woman due to the fluctuation of hormones even though the average age of fractures occurs in individuals aged 65 or older.[15]

Secondary prevention[edit]

Secondary prevention involves the screening of osteoporosis to identify those who may have a high risk.

Tertiary prevention[edit]

Tertiary prevention involves those who have already endured an osteoporotic fracture and are susceptible in causing a new one [16]

This table, created by myself, shows the preventive strategies broken down into the three subparts. The types of strategies used are decided by a health practitioner and the individual.

Drug and non-drug regimens[edit]

The prevention strategies can be broken into drug regimens and non-drug regimens. Hormone replacement therapy is a prevention strategy used for women that has a fracture-reducing potential based on observational studies. Calcium and vitamin D supplementation are also used in high risk groups. The cost of this strategy is low and was found to prevent new fractures in individuals in the tertiary group. Several large studies have been performed on primary fracture prevention with calcium and vitamin D supplementation and have shown a reduction in fractures with vitamin D dosages of at least 700 IU/day.[16] Bisphosphonates, which help to prevent the loss of bone mass, include the drugs Alendronate, Etidronate, and Residronate. They have been used in secondary and tertiary prevention. They are types of drugs that are used to treat osteoporosis and have shown to reduce hip fractures although more studies are currently being conducted. Other drug prevention therapies that are being used and studied are calcitonin, thiazide diuretics, and selective estrogen receptor modulators. Non-drug prevention strategies that are used are external hip protectors, general preventative measures, and home visits.

General prevention[edit]

“General” preventative measures include gait training, use of canes or other equipment to help with balance and gait, and the removal of hazardous material in homes such as loose flooring or improvement of the lightning in the home for the reduction of falls. A home visit by trained therapists or nurses specifically trained in this field is a preventative measure that is very costly.[17]

Epidemiology[edit]

Hip fractures are seen globally and are a serious concern at the individual and population level. By 2050 it is estimated that there will be 6 million cases of hip fractures worldwide.[18] One study published in 2001 found that in the US alone, 310,000 individuals were hospitalized due to hip fractures, which can account for 30% of Americans who were hospitalized that year.[19] Another study found that in 2011, femur neck fractures were among the most expensive conditions seen in US hospitals, with an aggregated cost of nearly $4.9 billion for 316,000 inpatient hospitalizations.[20] Falling, poor vision, weight and height are all seen as risk factors. Falling is one of the most common risk factors for hip fractures. Approximately 90% of hip fractures are attributed to falls from standing height.[21]

Population[edit]

All populations experience hip fractures but numbers vary with race, gender, and age. Women suffer hip fractures more often than men. In a lifetime, men have an estimated 6% risk whereas postmenopausal women have an estimated 14% risk of suffering a hip fracture.[22] These statistics provide insight over a lifespan and conclude that women are twice as likely to suffer a hip fracture. Caucasians are more likely to suffer hip fractures more than any other race. According to recent research, African Americans and Hispanics are the least likely to suffer hip fractures, which is thought to be because they have a greater bone density.[22]

Age related[edit]

Age is the most dominant factor in hip fracture injuries. The increase of age is related to the increase of hip fractures incidences.[18] Falls are the most common cause of hip fractures, around 30-60% of older adults fall each year. This increases the risk for hip fracture and leads to the increase risk of death in older individuals, the rate of one year mortality is seen from 12-37%.[23] For those remaining patients who do not suffer from mortality, half of them need assistance and cannot live independently. Also, older adults sustain hip fractures because of osteoporosis, which is a degenerative disease due to age and decrease in bone mass. The average age for suffering a hip fracture is 77 years old for women and 72 years old for men.[24] This shows how closely age is related to hip fractures.

References[edit]

  1. ^ TheFreeDictionary > hip fracture Citing: McGraw-Hill Concise Dictionary of Modern Medicine. Copyright 2002
  2. ^ Goldacre MJ, Roberts SE, Yeates D (October 2002). "Mortality after admission to hospital with fractured neck of femur: database study". BMJ 325 (7369): 868–9. PMC 129634. PMID 12386038. 
  3. ^ R. S. Garden. Obituary. British Medical Journal, vol 285, 11 December 1982, p.1751.
  4. ^ Hieu T Truong et al. Femoral Neck Fracture Imaging
  5. ^ Akhtar M Khan, Fractures of the Lower Limb
  6. ^ Bergström, U., Björnstig, U., Stenlund, H., Jonsson, H., & Svensson, O. (2008). Fracture mechanisms and fracture pattern in men and women aged 50 years and older: a study of a 12 year population-based injury register, Umea, Sweden. Osteoporosis International, 19, 1267-1273.
  7. ^ Hwang, H. F., Lee, H. D., Huang, H. H., Chen, C. Y., & Lin, M. R. (2011). Fall mechanisms, bone strength, and hip fractures in elderly men and women in Taiwan. Osteoporosis International, 22, 2385-2393.
  8. ^ Handoll, HH; Queally, JM; Parker, MJ (Dec 7, 2011). "Pre-operative traction for hip fractures in adults.". Cochrane database of systematic reviews (Online) (12): CD000168. doi:10.1002/14651858.CD000168.pub3. PMID 22161361. 
  9. ^ Tintinalli, Judith E. (2010). Emergency Medicine: A Comprehensive Study Guide (Emergency Medicine (Tintinalli)). New York: McGraw-Hill Companies. ISBN 0-07-148480-9. 
  10. ^ "Fractures of the Femoral Neck". Wheeless' Textbook of Orthopaedics. Duke University School of Medicine. Retrieved 27 January 2008. 
  11. ^ "Intertrochanteric Fractures". Wheeless' Textbook of Orthopaedics. Duke University School of Medicine. Retrieved 27 January 2008. 
  12. ^ "Damage Control Orthopaedics: Patient Stabilization, Early Mobilization". 74th Annual Meeting of the American Academy of Orthopaedic Surgeons briefing. Medical News Today. 18 Feb 2007. Retrieved 27 January 2008. 
  13. ^ a b Forsen, L., Arstad, C., Sandvig, S., Schuller, A., Roed, U., & Sogaard, A. "Prevention of hip fractures by external hip protectors: an intervention in 17 nursing homes in two municipalities in Norway". (2003). Scandinavian Journal of Public Health, 31, 261-266.
  14. ^ Frick, K., Kung, J., Parrish, J., & Narrett, M. (n.d.). Journal of the american geriatrics society. (2010). Evaluating the Cost-Effectiveness of Fall Prevention Programs that Reduce Fall-Related Hip Fractures in Older Adults, 58, 136-141.
  15. ^ Holzer, G., & Holzer, L. (n.d.). Geriatrics. (2007). Hip protectors and prevention of hip fracturs in older persons, 62(8), 15-20.
  16. ^ a b Vesterguard, P., Rejnmark, L., & Mosekilde, L. "Hip fracture prevention". (2001). PharmacoEconomics, 19(5), 449-468.
  17. ^ Crilly, R., Hillier, L., Mason, M., Gutmanis, I., & Cox, L. (n.d.). Journal of the american geriatrics society. (2010). Prevention of Hip Fractures in Long-Term Care: Relevance of Community-Derived Data, 58, 738-745.
  18. ^ a b Kannus P, Parkkari J, Sievanen H, Heinonen A, Vouri I, Jarvinen M. (1996) "Epidemology of hip fractures" Bone 1, 57-63
  19. ^ Huddleston JM, Whitford KJ. (2001) Medical Care of Elderly Patients with Hip Fractures" Mayo Clinic Proceedings 76, 295-300
  20. ^ Torio CM, Andrews RM. National Inpatient Hospital Costs: The Most Expensive Conditions by Payer, 2011. HCUP Statistical Brief #160. Agency for Healthcare Research and Quality, Rockville, MD. August 2013. [1]
  21. ^ Cumming RG, Nevitt MC, Cummings SR. (1997) Epidemiology of Hip Fractures. Epidemiology review, 19 (2), 244-257
  22. ^ a b Lauritzen JB. (1997) Hip fractures: Epidemiology, risk factors, falls, energy absorption, hip protectors, and prevention. Dan Med Bull, 44(2), 155-168
  23. ^ Rubenstein LZ, Josephson KR. (2002) The Epidemiology of Falls and Syncope. Clinic in Geriatrics Medicine, 18, 141-150
  24. ^ Baumgaertner MR, Higgins TF. (2002) Femoral Neck Fractures. Rockwood & Green’s Fractures in Adults. 1579-1586

External links[edit]