68 Bone Fractures

Fractures

A partial or complete break in any bone is termed a fracture and is most often the result of either accidental or intentional trauma.  Although a stress fracture can occur due to overuse or overload.

Risk Factors

In North America, the most common fractures occur in biological males aged 15-24 years old, and include fractures to the tibia, clavicle and lower humerus.  Workplace injuries often affect hands and feet in males.  The elderly become more at risk for fractures, as osteoporosis can develop, leading to susceptibility to fractures, most often hip (proximal femur) fractures and vertebrae compression fractures.  In Canada, one-third of females and one-fifth of males will experience a fracture in which osteoporosis has been a contributing factor.  Risk factors for bone fractures include: lack of dietary calcium and vitamin D, age, biological sex, workplace, high-risk behaviours, smoking, alcohol consumption, lack of physical activity, exposure to natural disasters or war, and certain sports (e.g., downhill biking, skiing, horse-back riding).

Names of Fractures

Fractures are categorized based on the angle of the break in the bone, the number of fragments, the region of the bone, and whether the bone punctures the skin.  Underlying conditions that factored into the bone break such as type of impact, direction of force or stress, and pathological weakening can also contribute to the naming of the bone fracture types.

Common types of fractures include oblique, transverse, spiral, linear, segmented, impacted (also known as buckled, or telescoped), comminuted, displaced, non-displaced, open, closed, incomplete (greenstick), compression, pathologic, Colles fracture (which occurs in the distal radius and sometimes includes the distal ulna), and Pott’s fracture (which occurs in the distal fibula and sometimes is accompanied by fracture of the distal tibia).  Stress fractures are common in athletes due to (overuse or fatigue of the tissue) and in the elderly due to insufficiency (weakening of the bone).  

Fractures – Signs & Symptoms

Fractures disrupt sensory nerve fibers that innervate bone resulting in the neurons signaling pain to the brain.  Sensory neurons with pain receptors (nociceptors) are abundant in the periosteum, the connective tissue that wraps around bone, as well as in the endosteum, the connective tissue that lines the medullary cavities.   The interior of bones are highly vascularized and the different types of nerve fibers that innervate bone are strongly associated with the vascular networks that penetrate the bone.  There are different types of nociceptors throughout the body, with each type sensitive to a particular set of stimuli.  Depending on the type of nociceptor triggered, different pain sensations (e.g., sharp pain, or slow burning pain) are evoked.  Overall, nociceptors are mechanosensors and contain chemical receptors that can be stimulated by mechanical and noxious temperature disruptions, as well as by chemicals released from damaged cells and severed blood vessels (e.g., potassium, acidity, adenosine triphosphate (ATP), acetylcholine, serotonin, substance P, and endothelins).  Nociceptors are also triggered by cytokines released from activated mast cells (e.g., prostaglandins, bradykinin, and leukotrienes).

Within the tissue of a fracture, the damaged blood vessels and disrupted cells will stimulate the chemotaxis of macrophages and mast cells.  The activated mast cells will release pro-inflammatory cytokines (bradykinin, prostaglandin, histamine, leukotriene), resulting in inflammation and all the signs and symptoms associated with inflammation.  Specifically, vasodilation and increased capillary permeability will result in an influx of blood (hyperemia), leading to an increase in redness, warmth, swelling (with the accumulation of fluid potentially pressure), and the development of hematoma(s).  the accumulation of fluid Pressure from inflammation can trigger nociceptors.

Fractures

Fracture – Diagnosis

Fractures are often diagnosed based on physical examination and imaging (e.g., X-ray, CT scan, MRI scan).

Fractures – Types and Treatments

Fractures are either closed, in which the overlying skin is intact, or open, in which the fractured bone is exposed to the outside world and is at risk for infection.  The first steps of treatment for both closed and open fractures involve cleaning the fracture site and realigning the bone ends or fragments through the use of splints, casts, pins, intramedullary nails, wires, cages, and/or traction.  Often open fractures are graded (Type I to IIIC) based on severity (size of wound, extent of damage to surrounding tissue, and amount of wound contamination).  The term reduction is often used and refers to the process by which the ends of the fractured bones are pulled/pushed together until they align and any gaps are reduced to ensure healing will take place.

Greenstick fractures are incomplete in that only one side of the bone is fractured (the periosteum and cortex) and the other side remains intact.   The periosteum and cortical (compact) bone on one side are damaged, and the bone does not break all the way through.  More often occur this type of fracture occurs before the age of 10 years old as children’s bones contain more calcified cartilage that adult bones which are more ossified and therefore less compliant.  Adults can experience incomplete or greenstick fractures.  Falls, sports, vehicle injuries that affect the long bones (fibula, tibia, ulna, humerus, radius and clavicle) are the greatest risk factors.  Outstretched arms when falling leading to the most common greenstick fractures of the ulna, radius or humerus.  These fractures are treated with the same strategies already mentioned – reduction and realignment.  These fractures are closed (not exposed to the external environment) and typically non-displaced (the broken bone remains aligned.   Therefore, closed reduction and immobilization (e.g., using a cast or splint) is often used, possibly with replacing the cast after several days once the edema (swelling) has subsided.

Avulsion fractures involve a break in which a bone fragment connected to a ligament or tendon is detached from the main bone.

Segmental fractures are defined as complete fractures that have 2 breaks in a bone and the segments of bones are now out of alignment or displaced.

Comminuted fractures are defined as complete fractures that have at least 3 breaks in one bone.  In some comminuted bone fractures, there has been shattering producing many bone shards and fragments some of which may be lost or not be capable of realigning and healing properly.  In this case it could be that bone grafts and bone cement in addition to cleaning the wound, and realigning the salvageable bone fragments that are present with pins, nails, wires is required.  Autogenous bone grafts from the patient’s hips, ribs or legs are typically used, if necessary.

Spiral fractures are complete fractures that often occur when a bending or twisting force is applied.

Compression fractures often occur in the vertebrae due to osteoporosis and because the weakness occurs more often in the anterior portion (the body) of the vertebrae a wedge fracture occurs potentially leading to changing the alignment and curvatures of the spine as well as causing severe back pain and loss of height.  Abnormal curvatures of the vertebrae known as scoliosis, kyphosis and lordosis can develop as a result.  Treatments can involve the use of bone cement in vertebroplasty as well as back brace support while the bone heals in addition to analgesics (e.g., NSAIDs).  At times, spinal fusions may be an option, which involve the use of metal plates and rods or bone grafts to hold and realign the affected vertebrae.  Any underlying causes (e.g., osteoporosis, primary or secondary tumors) are treated and the use of physical therapy can be helpful

Growth plate fractures may affect final adult height depending on severity of damage to the epiphyseal plate.  Unfortunately, crush injury to the epiphyseal plate commonly leads to premature growth cessation.  Proper reduction and fixation is required to optimize healing and minimize the risk of premature ossification of the epiphyseal plate.

Pathologic Fractures 

Pathologic fractures occur in focal regions of the bone that have are weaker due to an underlying disease or condition, such as malignant lesions (cancer), bone infection (e.g., osteomyelitis) or congenital bone disorder (e.g., osteogenesis imperfecta also known as brittle bone disease).  Treatment of the fracture is coupled with treatment of the underlying cause.

Stress Fractures – Risk Factors and Treatment

Stress fractures are hairline cracks in the bone.  There are two types of stress fractures: fatigue fractures and insufficiency fractures.

Fatigue fractures (also known as over-use fractures) occur due to abnormal (overuse) stresses on bone.  For example, athletes that train with an increase in frequency, intensity, and/or duration are susceptible to fatigue fractures.  Fatigue fractures occur most often amongst young biological females in feet or weight- or force-bearing limbs while participating in activities such as jumping, running, dancing, gymnastics, throwing, golfing, or racquet sports.

Insufficiency fractures occur when normal forces are applied to weakened bones.  In cases of insufficiency fractures, the bone has typically been weakened due to osteoporosis, osteomalacia, Rickets, Marfan syndrome or medical treatments (e.g., glucocorticoids, chemotherapy, or radiation therapy).  The vertebrae and sacrum are the most susceptible to insufficiency fractures, but other bones can also be affected (ilium, sternum, femur, fibula, and tibia).

Signs and symptoms of stress fractures include bone pain at rest, that worsens during activity as well as when the bone is pressed on.  There may be signs of inflammation.

Treatment for stress fractures includes PRICE (Protection, Rest, Ice, Compression, Elevation), pain and anti-inflammatory medication (e.g., NSAIDs), and possibly electrical stimulation.  The means of protection and rest may include the use of crutches, a walking boot, braces, or a cast).

Surgery is occasionally required for insufficiency fractures.  For example, sacral insufficiency fractures are common in the elderly (due to osteoporosis) and are sometimes treated with sacroplasty (using bone cement).

Shin Splints – Risk Factors and Treatment

Shin splints are not bone fractures, but are depicted by pain along the length of the inner tibia. Shin splints result from damage to the periosteum, tendons, or muscle surrounding the tibia most often due to a recent increase in the duration or frequency of a repetitive activity (e.g., walking, running, various sports). Signs and symptoms of shin splints include shins that are painful when touched. The pain often worsens when standing on tip toes or when the ankles are rotated.

Diagnosis is based on physical examination and imaging (e.g., x-rays) may be used.

Treatment involves RICE and possibly analgesics (e.g., NSAIDs). Taking a break from activities that cause pain is recommended. Participation in low impact activities (e.g., swimming) may be possible instead of high impact activities (e.g., running)

Prevention strategies involve use of supportive athletic shoes, and if beginning a new exercise or activity, being sure to ramp up activity (intensity, duration) level over weeks and months (rather than days). Strengthening and stretching exercises are also helpful.