Fracture

Original Editor - Esraa Mohamed Abdullzaher
Top Contributors - Jess Bell, Esraa Mohamed Abdullzaher, Naomi O'Reilly, Kalyani Yajnanarayan, Lucinda hampton, Khloud Shreif, Kim Jackson, Tarina van der Stockt, Claire Knott, Wanda van Niekerk, Abbey Wright, Aminat Abolade and Stacy Schiurring

Introduction

A fracture is a “complete or incomplete break in the anatomic continuity of bone, which leads to mechanical instability of the bone.”

The clinical features of fracture include pain, tenderness, bruising, swelling and sometimes deformity / movement restriction. Fractures tend to occur alongside other injuries, such as soft tissue, vascular or nerve injuries.

Fractures have different causes. Traumatic fractures occur when healthy bone is exposed to an overwhelming force (e.g. a fall or car accident). Repetitive sub-maximal loading fractures are often seen in running or jumping sports where there is a history of overload (i.e. stress fractures). Pathological fractures may occur in bones weakened by focal lesions (e.g. malignancy). Finally, specific bone conditions can lead to decreased bone density or softness of the bone (e.g. osteoporosis or osteomalacia).

“Bones can grow, modify their shape (external remodelling or modelling), self-repair when fractured (fracture healing) and continuously renew themselves by internal remodelling.”

To recap the types, general structure and function of bone, please see: Bone.

Types of Fractures

Types of bone fracture.

Fractures can be described or classified in a number of ways, including their cause (see above), severity, stability after reduction, location, etc.

Closed vs open fracture: closed fractures don’t break the skin whereas open fractures do break the skin. Open fractures cause more injury to local soft tissues, including the periosteum. The risk of infection and non-union is increased in open fractures.

Displacement: displacement describes the position of the fracture fragments in relation to an anterior / posterior or medial / lateral plane. In non-displaced (stable) fractures, the fracture ends are aligned. In displaced (unstable) fractures, the fracture ends are separated or misaligned

Angulation: describes the position of the fracture fragments in relation to the longitudinal axis of the bone.

Complete vs incomplete fracture: complete fractures extend across the whole bone. Examples include transverse fractures where the fracture is in a straight line across the bone or perpendicular to the bone’s axis; oblique fractures where the fracture occurs at an angle to the bone's axis; comminuted fractures where the bone is fractured in three or more parts; and spiral fractures where the fracture spirals around the bone. A spiral fracture is caused by a rotational force. They usually occur at the diaphysis of long bones.

Incomplete fractures do not extend across the whole bone, so they are considered partial fractures. They are more common in children. Examples include:

• bowing fracture: an incomplete fracture of tubular long bones that "occur as a plastic response to longitudinal stress"
• buckle fracture: the cortex of the bone “buckles” in response to a direct axial load. They tend to occur in the long bones of children
• greenstick fracture: the cortex and periosteum are interrupted on one side of the bone only

Stress fracture: in stress fractures, repeated stress / overuse leads to microscopic fractures.

Impacted fracture: in an impacted fracture, the fracture ends are driven into each other (e.g. after a fall or direct trauma).

Compression fracture: these fractures occur when a bone is crushed. In compression fractures, bones become flatter or wider. In the spine, they are associated with osteoporosis and are caused by axial or compressive loads.

Segmental fracture: in this type of fracture, a bone is fractured in two places and a segment of bone “floats” between the two fractures.

Avulsion fracture: a small piece of bone is pulled off by a tendon or ligament. Avulsion fractures are most commonly caused by a "sudden, tensile force to the bone through the soft tissue, or when chronic repetitive avulsive stresses lead to a piece of bone being pulled away by the soft tissue".

Location: fractures are also described based on their location on the bone:

• parts of the bone: metaphysis, diaphysis, epiphysis (see below)
• specific structures: epicondyle, tubercle, etc.
• intra-articular (fractures can enter the joint space or affect the articular surface) or extra-articular
• anatomical site: proximal end, proximal third, mid third, distal third, distal end

Growth plate fractures (or epiphyseal fractures, Salter-Harris fractures): the epiphyseal growth plate in children is particularly susceptible to injury. 15-30% of all paediatric bony injuries are epiphyseal fractures. They are associated with an increased risk of leg length discrepancies and angular deformities. They are typically graded using the Salter-Harris classification system. For more information, please see: Salter-Harris Fractures. This optional video describes fracture types and causes in a bit more detail:

Bone Healing After Fracture

"We're constantly breaking bone down and regenerating bone for our calcium homeostasis. That gives us the ability to heal bone back to its original structure. However, everything has to go right for that to occur." -- Shala Cunningham

Bone healing in cortical bone after fracture can be primary or secondary.

Primary healing (also called direct or intramembranous ossification): Primary bone healing can only occur when the bony fragments are "tightly fixed together under compression." There is no movement at the fracture site (achieved through surgical fixation), so no callus is formed. The bones are connected via osteoblast and osteoclast activity.

Secondary healing (also called indirect or endochondral ossification): in secondary healing, there is some movement at the fracture site. This is the most common type of fracture healing.

This optional video briefly describes the difference between primary and secondary healing:

Secondary healing in cortical bone includes the following four phases.

Phase one: haematoma formation and inflammatory response: a haematoma forms at the fracture site, which acts as a temporary scaffold. Local tissue volume increases because of inflammation. Acute inflammatory markers (e.g. tumor necrosis factor alpha (TNF-α), IL-1, IL-6) are recruited. These inflammatory markers attract macrophages, monocytes, and lymphocytes to the area. They remove necrotic tissue and release cytokines, which stimulates healing and promotes the formation of new blood vessels (angiogenesis). The time frame given for this phase of healing varies in the literature - it is typically described as lasting for 5-7 days, but some authors note it can last longer. The end of this phase is associated with a decrease in pain and swelling.

Phase two: formation of soft (fibrocartilaginous) callus: mesenchymal stem cells are recruited and they differentiate into fibroblasts, osteoblasts, and chondroblasts. Chondrogenesis (i.e. early bone development) begins and the soft callus forms, replacing the haematoma. There is a small increase in mechanical strength during this phase of healing. The time frame given for this phase of healing also varies in the literature, but it is usually said to start around day 5 and can continue for 2-3 weeks.

Phase three: the hard callus forms from the soft callus, uniting the bone ends: this process is called endochondral ossification. During this phase, the soft callus is resorbed and woven bone is deposited. Once the hard callus is in place, patients can start to weight bear and external stabilisers (splints and casts) are usually removed. Again, the time frames for this phase vary in the literature, but as a general guide, bone union usually occurs 4-6 weeks after injury in the upper limb and 8-12 weeks after injury in the lower limb.

Phase four: bone remodelling. During this final phase of healing, osteoclasts and osteoblasts work to remodel the new bone, ensuring the bone at the fracture site is as strong and rigid as normal bone. The remodelling phase can last for months to years.

The following optional videos explain fracture healing in more detail:

Healing in cancellous (or trabecular) bone, found primarily in metaphyseal regions and vertebrae, heals differently from cortical bone. The healing process primarily involves intramembranous ossification - there is almost no cartilage intermediary. When fracture fragments are in close contact, bone is laid down directly on existing bone without significant callus formation. The stages of intramembranous ossification are: (1) initial resorption where necrotic tissue in the fracture gap is resorbed, (2) osteoblastic activity, where osteoblasts start to deposit bone around existing trabeculae on both sides of the fracture gap - this trabeculae thickening is often seen on radiographs as a bright band by a radiolucent band (i.e. the fracture gap), and (3) gap bridging, where osteoblasts start to fill the fracture gap with new bone once the trabeculae are reinforced.

Signs of Healing in Fractures

"Although fracture healing is generally defined as the restoration of the bone biomechanical function, it is difficult to define when this biomechanical feature is achieved at the previous fracture site."

There is a lack of consensus on how to assess fracture healing. However, common clinical criteria to indicate healing include (1) evidence of callus formation on radiology, CT, MRI or ultrasound, (2) absence of pain / tenderness on weight bearing, (3) absence of pain / tenderness on palpation and (4) the ability to weight bear.

Corrales et al. list common clinical criteria that have been used to define fracture union here.

Factors Affecting Bone Healing

A number of local and systemic factors affect bone healing.

Local factors include the degree of local trauma and the blood supply. Blood supply at the fracture site initially decreases. It then increases after a few hours to days, peaking at around 2 weeks. It then reduces / normalises from 3-5 months. Reduced blood supply can result in delayed union or non-union. The location of fracture is an important local factor. It is believed that bone healing in the metaphysis, which is rich in trabecular bone, progresses more quickly than areas rich in cortical bone, like the diaphysis. The type and severity of fracture have an impact, as comminuted fractures heal more slowly. The degree of immobilisation and type of fixation have an impact as increased movement at a fracture site slows healing. Finally, infection compromises healing.

Systemic factors include the patient's age - our healing potential decreases with increased age and nutrition status. A healthy diet enhances healing while a diet that lacks specific nutrients, vitamins, and calcium can affect bone health and healing. Other systemic factors include smoking, which can delay bone healing, co-morbidities (e.g. diabetes, osteoporosis, chronic stress, etc.), non-steroidal anti-inflammatory drugs and alcohol misuse.

Fracture Complications

There are various complications associated with fractures, including delayed union, non-union or malunion. Delayed union is when a fracture takes longer to heal than expected, non-union is when the fracture doesn't heal and malunion is when the fracture heals out of alignment, resulting in deformity.

Soft tissue injuries occur with fracture. These can cause secondary dysfunction, disuse and adhesions.

Other complications include osteonecrosis (also known as avascular necrosis), infection / osteomyelitis, particularly in open fractures, vascular injury, nerve injury and acute compartment syndrome. Acute compartment syndrome is more common in forearm fractures. Deep vein thrombosis and pulmonary embolism can also occur, more commonly in lower limb fractures. Fracture can also cause intra-articular and peri-articular adhesions and capsulitis.

The following video explains various fracture complications in more detail. The video contains real images of wounds, fractures, etc and therefore it is age restricted and won’t automatically play on the site. If you’re interested, you will need to click the link to watch it on YouTube. You can also read more about fracture complications here.

Fracture Management

Fracture management focuses on achieving anatomical and functional alignment. This is achieved in different ways depending on the fracture:

• bracing and casting are used for non-displaced / minimally displaced fractures
• reduction and immobilisation are used for displaced fractures
• surgical stabilisation is typically required for displaced, unstable fractures - this often involves open reduction (surgical realignment) and internal fixation (e.g., plates, screws, rods)

Fracture management will depend on many different factors, including the type and severity of a fracture, how it has been fixed, the stability of the fracture, individual factors, the stage of healing, etc. Depending on the injury, the physiotherapy and rehabilitation management may focus on the following aspects.

Initial phase (immobilisation / early healing): during the initial phase, treatment focuses on pain management and swelling reduction while maintaining the mobility of joints above and below the fracture. This phase also includes patient education on weight-bearing status, necessary precautions, and techniques for safe transfers and movements.

Post-immobilisation (after the cast or brace is removed): the post-immobilisation phase concentrates on restoring range of motion while implementing progressive strengthening exercises and functional rehabilitation techniques. During this period, scar management is also addressed to promote optimal healing and minimise tissue restrictions.

Advanced rehabilitation: involves progressive strengthening exercises complemented by balance and proprioception training, as well as gait re-training to restore normal walking patterns. This phase focuses on facilitating the patient's return to work, sport, and activities of daily living while addressing any identified deficits that may impact functional performance.