Hip fracture

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.[5]

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.

Many people 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, increases the risk of medical illness including heart attack, stroke, and chest infection.

Hip fracture patients are at considerable risk for thromboemoblism, blood clots that dislodge and travel in the bloodstream.[5] 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 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.

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.[7][8][9]

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.

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.[11][12][13] Elderly tend to fall to the side as instead of forward, and the lateral hip and strikes the ground first.[5] During a sideways fall, the chances of hip fracture see a 15-fold and 12-fold increase in elderly males and females, respectively.

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.[5][14][15]

Displaced fractures of the trochanter or femoral neck will classically cause external rotation and shortening of the leg when the patient is laying supine.[5]

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.[5] 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.[16]

A case demonstrating a possible order of imaging in initially subtle findings:

• 
  X-ray showing a suspected compressive subcapital fracture as a radiodense line
• 
  CT scan shows the same, atypical for a fracture since the cortex is coherent
• 
  T1-weighted, turbo spin echo, MRI confirms a fracture, as the surrounding bone marrow has low signal from edema.

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.

Hip fracture classification.[17]

Subcapital fracture in a 92-year-old woman

Fracture (black arrow, pertrochanteric) versus a skin fold (white arrow).

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

Trochanteric fractures are subdivided into either intertrochanteric (between the greater and lesser trochanter[18]) or pertrochanteric (through the trochanters[18][19]) by the Müller AO Classification of fractures.[20] Practically, the difference between these types is minor. The terms are often used synonymously.[21][22] 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.[23] Yet, an isolated trochanteric fracture may not be regarded as a true hip fracture because it is not cross-sectional.

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.

Fractures managed by closed reduction can possibly be treated by percutaneously inserted screws.[37]

In elderly patients with displaced or intracapsular fractures surgeons may decide to perform a hemiarthroplasty, replacing the broken part of the bone with a metal implant.[38] However, in elderly people who are medically well and still active, a total hip replacement may be indicated. Independently mobile older adults with hip fractures may benefit from a total hip replacement instead of hemiarthroplasty.[39]

Traction is contraindicated in femoral neck fractures due to it affecting blood flow to the head of the femur.[40]

The latest evidence suggests that there may be little or no difference between screws and fixed angle plates as internal fixation implants for intracapsular hip fractures in older adults.[41] The findings are based on low quality evidence that can't firmly conclude major difference in hip function, quality of life, and additional surgery.

Fracture supported by dynamic hip screw

A trochanteric fracture, below the neck of the femur, has a good chance of healing.

Closed reduction may not be satisfactory and open reduction then becomes necessary.[42] The use of open reduction has been reported as 8-13% among pertrochanteric fractures, and 52% among intertrochanteric fractures.[43] Both intertrochanteric and pertrochanteric fractures may be treated by a dynamic hip screw and plate, or an intramedullary rod.[42]

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.

Subtrochanteric fractures may be treated with an intramedullary nail or a screw-plate construction and may require traction pre-operatively, though this practice is uncommon. It is unclear if any specific type of nail results in different outcomes than any other type of nail.[44]

A lateral incision over the trochanter is made and a cerclage wire is placed around the fracture for reduction. Once reduction has been achieved a guide canal for the nail is made through the proximal cortex and medullary. The nail is inserted through the canal and is fixated proximally and distally with screws. X-rays are obtained to ensure proper reduction and placement of the nail and screws are achieved.[45]

Rehabilitation has been proven to increase daily functional status. Forty percent of individuals with hip fractures are also diagnosed with dementia or mild cognitive impairment which often results in poorer post-surgical outcomes.[46] In such cases enhanced rehabilitation and care models have been shown to have limited positive effects in reducing delirium and hospital length of stay.[46] It is unclear if the use of anabolic steroids affects recovery.[47]

A updated Cochrane review (2022) involving over 4000 patients found evidence that gait training, balance and functional tasks training to be particularly effective when compared to conventional care.[48] There is also moderate-certainty evidence that rehabilitation after hip fracture surgery, when delivered by a multidisciplinary team and supervised by an appropriate medical specialist, results in fewer cases of 'poor outcome', like death and deterioration in residential status.[49]

Oral supplements with non-protein energy, protein, vitamins and minerals started before or early after surgery may prevent complications during the first year after hip fracture in aged adults; without seemingly effects on mortality.[50]

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.

Among those affected over the age of 65, 40% are transferred directly to long-term care facilities, long-term rehabilitation 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. Most of the recovery of walking ability and activities of daily living occurs within 6 months of the fracture.[54] After the fracture about half of older people recover their pre-fracture level of mobility and ability to perform instrumental activities of daily living, while 40–70% regain their level of independence for basic activities of daily living.[54]

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.

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%.

All populations experience hip fractures but numbers vary with race, gender, and age. Women have three times as many hip fractures as men.[62] In a lifetime, men have an estimated 6% risk whereas postmenopausal women have an estimated 14% risk of having a hip fracture.[63] These statistics provide insight over a lifespan, and conclude that women are twice as likely to have a hip fracture. The overwhelming majority of hip fractures occur in white individuals, while blacks and Hispanics have a lower rate of them. This may be due to their generally greater bone density and also because whites have longer overall lifespan and higher likelihood of reaching an advanced age where the risk of breaking a hip goes up.[63] Deprivation is also a key factor: in England, it has been found that people in the poorest parts of the country are more likely to fracture a hip and less likely to recover well than those in the least deprived areas.[64]

Age is the most dominant factor in hip fracture injuries, with most cases occurring in people over 75. The increase of age is related to the increase of the incidence of hip fracture,[56] which is the most frequent cause of hospitalization in centenarians, overcoming congestive heart failure and respiratory infection.[65] 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 increased risk of death in older individuals, the rate of one year mortality is seen from 12 to 37%.[66] For those remaining patients, 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 sustaining a hip fracture is 77 years old for women and 72 years old for men.[67]