Bone fracture
A bone fracture is a medical condition in which there is a partial or complete break in the continuity of any bone in the body, disrupting its structural integrity.[1] These injuries occur when the applied force exceeds the bone's capacity to withstand stress, ranging from sudden high-impact trauma to repetitive microtrauma or underlying bone weakness.[2] Fractures are among the most common musculoskeletal injuries, affecting individuals of all ages, though they are particularly prevalent in children due to active lifestyles and in older adults due to reduced bone density.[3] The primary causes of bone fractures include direct trauma from falls, motor vehicle accidents, or sports-related impacts, which account for the majority of cases.[4] Stress fractures arise from repetitive loading on the bone without adequate recovery time, often seen in athletes or military personnel engaging in high-impact activities like running.[2] Additionally, pathologic or insufficiency fractures result from normal stresses on weakened bones, commonly due to conditions such as osteoporosis, tumors, or metabolic disorders that compromise bone quality.[5] Bone fractures are classified by several criteria to guide diagnosis and treatment. Based on skin involvement, they are categorized as closed (simple), where the bone remains beneath the skin, or open (compound), where the broken bone pierces the skin, increasing infection risk.[3] Pattern-based classifications include transverse (straight across the bone), oblique (angled), spiral (twisting force), comminuted (bone shatters into multiple pieces), and impacted (bone fragments driven together). Other types encompass greenstick fractures (incomplete breaks, common in children) and stress fractures (small cracks from overuse).[1] Symptoms typically involve intense pain, swelling, bruising, deformity, and limited mobility at the site, necessitating prompt medical evaluation via physical exam and imaging like X-rays.[1] Treatment depends on fracture type, location, and severity but generally aims to realign the bone (reduction) and stabilize it for healing. Non-surgical options include immobilization with casts, splints, or braces for 4-8 weeks, while severe cases may require surgical fixation using plates, screws, or rods.[3] Healing occurs through a biological process involving inflammation, soft callus formation, hard callus development, and remodeling, typically taking 6-8 weeks for most fractures in healthy individuals, though complications like infection, nonunion, or malunion can prolong recovery.[6] Prevention strategies emphasize maintaining bone health through adequate calcium and vitamin D intake, weight-bearing exercise, fall prevention measures, and protective equipment during high-risk activities.[1]Overview
Definition
A bone fracture is defined as a break or crack in the continuity of bone tissue, resulting in a disruption of the bone's structural integrity. This distinguishes fractures from soft tissue injuries such as sprains, which involve ligament damage, or strains, which affect muscles or tendons, as fractures specifically pertain to the skeletal system.[6] Bone anatomy plays a key role in understanding fractures, with bones composed of cortical (compact) bone, which forms the dense outer layer providing strength and support, and cancellous (trabecular) bone, which is spongy and found primarily in the interior, offering flexibility and shock absorption. The periosteum, a tough fibrous membrane covering the outer surface of bone (except at joints), is crucial in fracture contexts as it supplies blood vessels, nerves, and progenitor cells essential for bone repair and remodeling.[7][8][6] Fractures are broadly classified by extent and exposure: complete fractures involve a full break across the bone, separating it into distinct segments, while incomplete fractures feature partial cracks that do not fully divide the bone, such as greenstick or hairline types often seen in children. Additionally, closed (simple) fractures occur when the bone breaks without piercing the skin, maintaining an intact overlying soft tissue envelope, whereas open (compound) fractures result in the bone protruding through the skin or communicating with an external wound, increasing infection risk.[9][10] The medical recognition of bone fractures dates back to ancient times, with the earliest detailed descriptions appearing in the works of Hippocrates around 400 BCE, who classified various fracture patterns and outlined basic reduction techniques in texts like On Fractures.[11] Fractures commonly affect long bones such as the femur, though they can occur in any skeletal element depending on the circumstances.Epidemiology
Bone fractures impose a substantial global health burden, with an estimated 178 million new cases occurring worldwide in 2019, marking a 33.4% increase in absolute numbers since 1990 despite a decline in age-standardized incidence rates to 2296.2 per 100,000 population.[12] In the United States, approximately 1.5 to 2 million fractures are treated annually, though rates are notably higher in developing countries, where trauma from road traffic accidents and violence is a major contributor to severe fracture cases.[13][14] Demographic patterns reveal distinct variations by age and gender. Incidence peaks in children aged 11-14 years, primarily from falls, with rates around 1,300-1,700 per 100,000 in boys at peak ages.[15] Among adults under 50, males experience higher rates due to high-energy trauma, such as sports injuries or accidents, with male-to-female ratios exceeding 1.6:1 in this group.[16] In contrast, females over 50 face elevated risk from low-energy falls linked to osteoporosis, accounting for about one-third of women and one-fifth of men in this age group sustaining an osteoporotic fracture in their lifetime.[17] The most common fracture sites differ by population. In adults overall, distal radius fractures predominate, comprising about 18% of cases, followed by proximal femur, ankle, proximal humerus, and proximal tibia.[18] Among the elderly, proximal femur (hip) fractures are a major type of fragility fracture in women over 65, accounting for approximately 20% of such cases.[19] Epidemiological trends indicate a rising burden driven by aging populations. Worldwide, hip fracture incidence is projected to increase by 310% in men and 240% in women by 2050 compared to 1990 levels. More recent projections from 2023 indicate that hip fractures will nearly double globally by 2050 compared to 2018.[20][21] Post-2020 data from the COVID-19 pandemic suggest a potential uptick in fragility fractures in some regions, attributed to sedentary lifestyles, reduced physical activity, and vitamin D deficiencies during lockdowns.[22] Morbidity and mortality remain high, especially for hip fractures in the elderly, with one-year post-fracture mortality rates ranging from 20% to 30%.[23][24]Causes and Risk Factors
Mechanisms of Injury
Bone fractures occur when the applied mechanical forces exceed the bone's capacity to withstand them, leading to structural failure. The primary mechanisms involve various types of loading that deform the bone beyond its elastic limit, resulting in crack initiation and propagation. These forces can act singly or in combination, depending on the injury event.[25] The main types of forces responsible for fractures include tensile, compressive, shear, torsional, and bending loads. Tensile forces stretch the bone, pulling it apart along its length and often leading to transverse fractures; cortical bone typically fails in tension at stresses around 130 MPa. Compressive forces crush the bone, shortening it and commonly producing impacted or compression fractures, with failure thresholds near 190 MPa longitudinally. Shear forces cause layers of bone to slide past one another, resulting in oblique or irregular fracture patterns, as bone is weakest under shear loading. Torsional forces twist the bone, generating spiral fractures due to the rotational stress along the bone's axis. Bending loads combine tension on the convex side and compression on the concave side, often seen in three- or four-point bending scenarios, leading to bowing or transverse fractures at the midpoint of the load application.[26][25] Fractures are broadly classified by the energy level of the trauma: high-energy versus low-energy. High-energy trauma involves substantial force, such as motor vehicle accidents or falls from height, which can cause comminuted or displaced fractures due to the rapid, intense loading that overwhelms bone's toughness. In contrast, low-energy trauma, like a simple fall from standing height, typically results in simpler fracture patterns, such as stable transverse breaks, as the force is more gradual and localized.[28] Mechanisms can also be direct or indirect based on force application. Direct mechanisms apply force immediately at the fracture site, such as a blow from an object causing a localized impact fracture. Indirect mechanisms transmit force along the limb from a distant point, like a fall on an outstretched hand propagating axial load to the humerus, resulting in fractures away from the impact area.[29] Biomechanical thresholds for fracture vary by bone type, age, and loading direction, but cortical bone generally yields at stresses of 100-200 MPa under physiological conditions, beyond which plastic deformation and failure occur. For instance, the yield stress in tension is approximately 100-150 MPa, while compression can tolerate up to 150-200 MPa before buckling. These limits highlight bone's anisotropic nature, being strongest longitudinally but vulnerable transversely.[25][30] Specific examples illustrate these mechanisms. Avulsion fractures arise from indirect tensile forces where a sudden muscle contraction pulls a bone fragment at its tendon or ligament attachment, common in the ankle or pelvis during sports. Stress fractures develop from repetitive low-energy loading, such as prolonged running, causing cumulative microdamage that accumulates beyond repair capacity, often in weight-bearing bones like the tibia or metatarsals.[31][32]Predisposing Factors
Bone density issues significantly predispose individuals to fractures by reducing skeletal strength and increasing fragility. Osteoporosis, characterized by low bone mineral density (BMD) and microarchitectural deterioration, affects approximately 30-50% of postmenopausal women, with prevalence estimates reaching up to 37.5% for osteoporosis and 44.7% for osteopenia in this group.[33] Osteopenia, a milder form of bone loss, serves as a precursor and elevates fracture risk, with 10-year cumulative fragility fracture incidence at 37.5% in affected postmenopausal women compared to 31.1% in those with normal BMD.[34] Lifestyle factors further compromise bone integrity through modifiable behaviors that impair BMD accrual or maintenance. Sedentary behavior contributes to muscle weakness and reduced bone loading, thereby heightening fracture susceptibility by negatively impacting BMD.[35] Poor nutrition, particularly deficiencies in calcium and vitamin D, weakens bone structure; low vitamin D levels are linked to decreased BMD and increased fracture risk, while inadequate calcium intake exacerbates this vulnerability.[36] Smoking accelerates bone loss and increases fracture risk, with heavy smokers facing up to 70% higher risk.[37] Excessive alcohol consumption accelerates bone loss and increases fracture risk, independent of other factors.[37] Certain medical conditions and treatments inherently elevate fracture propensity by disrupting bone metabolism. Rheumatoid arthritis (RA) doubles the risk of hip and vertebral fractures due to chronic inflammation and associated corticosteroid therapy.[38] Hyperparathyroidism promotes excessive bone resorption through elevated parathyroid hormone levels, leading to secondary osteoporosis and heightened fragility fracture rates.[39] Long-term corticosteroid use, common in inflammatory conditions, induces rapid bone loss, with up to 50% of users developing fractures, particularly vertebral and hip, within months of initiation.[40] Genetic influences play a foundational role in fracture susceptibility by modulating bone mass and quality. A family history of fractures doubles the risk among descendants, independent of BMD, as genetic factors account for 60-85% of BMD variability.[41] In rare cases, mutations in collagen type I alpha 1 genes, as seen in osteogenesis imperfecta, severely impair bone matrix formation, resulting in extreme fragility and recurrent fractures from minimal trauma.[42] Recent data indicate that SARS-CoV-2 infection induces persistent inflammation and immobility, leading to bone loss and an approximately 22% increased fragility fracture risk (HR 1.22) in affected populations, particularly older adults with preexisting vulnerabilities, as of 2024.[43]Clinical Presentation
Signs and Symptoms
Bone fractures typically present with sudden, severe pain that is localized to the injury site and intensifies with any movement or pressure on the affected area.[9] Swelling and bruising often develop rapidly, within hours of the injury, due to the formation of a hematoma from bleeding at the fracture site.[6] Deformity may be evident, such as angulation or shortening of the limb, along with loss of normal function, including inability to bear weight or move the area effectively.[44] Crepitus, a grating sensation or sound produced by bone fragments rubbing together, can occur when attempting to move the injured part.[45] In open fractures, where the bone pierces the skin, systemic signs include visible bleeding and exposed bone, which heighten the risk of infection if not addressed promptly.[46] Variations in presentation depend on the fracture location; for instance, a Colles' fracture of the distal radius often results in a characteristic "dinner fork" deformity, where the wrist appears bent backward with dorsal angulation.[47] If left untreated, these initial signs can progress to more severe issues, underscoring the need for timely medical evaluation.[9]Immediate Complications
Immediate complications of bone fractures encompass acute adverse events that can arise shortly after injury, potentially threatening limb viability and systemic stability if not promptly addressed. Neurovascular compromise represents a critical immediate risk, particularly in fractures of the extremities where swelling or direct trauma can impair blood flow and nerve function. Compartment syndrome, a hallmark of this compromise, occurs when intracompartmental pressure exceeds 30 mmHg, leading to ischemia of muscles and nerves within the fascial envelope.[48] This condition is most common following tibial or forearm fractures, with pressures approaching or surpassing diastolic blood pressure causing irreversible tissue damage within hours.[49] Arterial injuries further exacerbate neurovascular threats; for instance, popliteal artery disruption is a well-documented sequela of proximal tibial fractures, often resulting from traction or direct laceration during high-energy trauma, with rates approaching 5-10% in such cases.[50] These vascular insults can manifest as absent distal pulses or cool extremities, necessitating urgent vascular imaging and intervention to prevent amputation.[51] Hemorrhage constitutes another profound immediate complication, especially in fractures involving vascular-rich regions like the pelvis, where disruption of venous plexuses or arteries can lead to significant blood loss. In unstable pelvic fractures, hemorrhage volumes can reach 1-2 liters, contributing to hemorrhagic shock in up to 10-20% of severe cases, with venous bleeding accounting for approximately 85-90% of the total.[52] This rapid exsanguination arises from the retroperitoneal space's capacity to accommodate large volumes, often exceeding 1.5 liters before tamponade effects, and is a leading cause of early mortality in polytrauma patients.[53] In open fractures, where bone protrudes through the skin, infection emerges as an immediate concern due to bacterial contamination from the external environment. The Gustilo-Anderson classification stratifies this risk: type I fractures (clean wounds <1 cm) carry a low infection rate of 0-2%, while type II (wounds 1-10 cm without extensive damage) range from 2-5%; type III fractures, characterized by extensive soft-tissue injury, contamination, or vascular compromise, exhibit risks escalating to 10-50%, particularly in IIIB subtypes with periosteal stripping.[54] Factors such as wound contamination level and delay in debridement amplify this peril, with gram-negative and anaerobic organisms predominant in high-grade cases.[55] Fat embolism syndrome (FES) poses a systemic immediate complication primarily after fractures of long bones, such as the femur or tibia, where marrow fat globules enter the circulation. Symptoms typically onset within 24-72 hours post-injury, including petechial rash on the conjunctiva or axillae, acute respiratory distress with hypoxemia, and neurological alterations like confusion or seizures, fulfilling Gurd's criteria in 1-5% of at-risk patients.[56] This triad arises from pulmonary vascular occlusion and cerebral embolization, with early recognition vital to mitigate multi-organ involvement.[57] Recent studies as of 2025 have heightened awareness of thromboembolic events as an underrecognized immediate sequela following lower limb fractures, with deep vein thrombosis (DVT) incidence approximating 10-20% in immobilized patients, driven by venous stasis and endothelial injury.[58] Lower extremity fractures, particularly of the femur or tibia, elevate pulmonary embolism risk within the first week, underscoring the need for early thromboprophylaxis in high-risk cohorts.[59]Pathophysiology
Fracture Healing Mechanisms
Fracture healing is a dynamic biological process that restores bone integrity following injury, involving coordinated cellular and molecular events to regenerate tissue structurally and functionally similar to the original bone. This regenerative capacity relies on the activation of resident stem cells, inflammatory responses, and biomechanical influences at the fracture site. The process typically progresses through distinct but overlapping stages, modulated by local factors such as vascularity and mechanical stability.[6] The initial stage, hematoma formation, occurs within days 1-5 after fracture, when disrupted blood vessels lead to bleeding and clot formation at the site, providing a scaffold rich in growth factors and hematopoietic cells that initiates repair. This is followed by the inflammatory phase (weeks 1-3), characterized by the influx of inflammatory cells like macrophages and neutrophils, which clear debris and release cytokines to recruit mesenchymal stem cells (MSCs) for tissue regeneration; during this period, a soft callus of granulation tissue and fibrocartilage begins to bridge the fracture gap. The repair stage (weeks 3-12) involves the formation of a hard callus through endochondral ossification, where the soft callus is mineralized into woven bone, offering mechanical strength. Finally, the remodeling stage spans months to years, during which osteoclasts resorb excess bone and osteoblasts deposit organized lamellar bone, restoring the bone's original architecture.[60] Key cellular players include osteoclasts, which resorb damaged bone matrix and excess callus during remodeling; osteoblasts, derived from MSCs, that synthesize new bone matrix and express RANKL to regulate osteoclast activity; and chondrocytes, which produce the cartilaginous soft callus and later undergo apoptosis to facilitate ossification. Growth factors such as bone morphogenetic protein-2 (BMP-2) play a pivotal role by promoting the differentiation of MSCs into osteoblasts and chondrocytes, enhancing chondrogenesis and osteogenesis within the callus.[6][61] Fracture healing occurs via two primary pathways: primary (direct) healing, which involves intramembranous ossification without callus formation and requires absolute stability with interfragmentary strain below 2%, as seen in rigidly fixed fractures allowing direct osteonal bridging; and secondary (indirect) healing, the more common pathway involving callus formation through endochondral ossification under relative stability with strain between 2% and 10%, typically achieved with non-rigid immobilization like casts or intramedullary nails.[6][60] Timelines vary based on fracture characteristics and patient factors; simple fractures in young adults often unite in 6-8 weeks, while complex or unstable fractures may extend beyond this due to delayed callus formation. Adequate blood supply is essential, peaking at 2 weeks post-fracture to support angiogenesis and nutrient delivery, with impaired vascularity leading to delayed progression through the stages. Immobilization stability is crucial, as appropriate mechanical loading promotes callus development, whereas excessive motion (>10% strain) can disrupt early repair and lead to nonunion. Smoking can impair these mechanisms by reducing vascularity and delaying union, increasing nonunion risk.[60][6][62]Modifying Influences
Several factors can modify the outcomes of fracture healing by influencing vascular supply, cellular activity, and inflammatory responses. Smoking is a prominent external modifier that impairs bone repair. It reduces vascularity at the fracture site, leading to delayed union and increased risk of nonunion or complications. Studies indicate that fractures in smokers take approximately six weeks longer to heal compared to non-smokers, with nicotine specifically inhibiting osteoblast function and angiogenesis essential for callus formation.[63][62][64] Nutritional status also significantly affects healing timelines. Protein deficiency can prolong the inflammatory phase by limiting the availability of amino acids needed for tissue repair and matrix synthesis. Conversely, adequate vitamin C intake supports collagen cross-linking and synthesis, which are critical for early callus development; deficiency has been linked to delayed healing in both preclinical and clinical settings.[65][66] Certain medications alter healing dynamics through their effects on inflammation and bone turnover. Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit prostaglandin synthesis, which may delay callus formation and increase the risk of nonunion, particularly with prolonged use. Bisphosphonates, commonly prescribed for osteoporosis to enhance bone mineral density, generally do not significantly prolong fracture healing time but carry a risk of atypical fractures with long-term use due to suppressed remodeling.[67][68][69] Comorbidities introduce internal modifiers that impair repair processes. In diabetes, hyperglycemia promotes advanced glycation end-products and chronic inflammation, impairing angiogenesis and prolonging healing by 87%, alongside reduced bone formation. Advanced age contributes through diminished mesenchymal stem cell function and proliferative capacity, leading to slower union rates and higher complication risks independent of other factors.[70][71][72] As of 2025, emerging research highlights the role of biologics in modulating healing among patients with inflammatory diseases. Anti-TNF agents, such as adalimumab, reduce systemic inflammation and may preserve or increase bone mineral density, potentially mitigating delays in fracture repair by countering excessive cytokine-driven resorption in conditions like rheumatoid arthritis.[73][74]Diagnosis
History and Physical Examination
The initial clinical assessment for a suspected bone fracture begins with a detailed patient history to guide the diagnosis and management. Key elements include the mechanism of injury, such as high-energy trauma from motor vehicle accidents, low-energy falls in older adults, or twisting forces in sports-related incidents, which helps predict fracture patterns and associated soft tissue or visceral injuries.[75] The onset, location, quality, and severity of pain should be documented, along with any immediate symptoms like inability to bear weight or use the limb, as these indicate acute structural compromise.[76] Inquiry into comorbidities, such as osteoporosis, diabetes, or malignancy, is essential, as they predispose to fractures or complicate healing, while current medications like anticoagulants or bisphosphonates must be noted for their impact on bleeding risk and bone metabolism.[77] Physical examination proceeds systematically to localize the injury and assess for complications, starting with inspection of the affected area for deformity, swelling, ecchymosis, or skin breaks suggestive of an open fracture.[75] Palpation follows, evaluating for focal tenderness, crepitus (grating sensation from bone ends), or abnormal motion, which confirm bony disruption while avoiding excessive manipulation to prevent further damage.[78] A critical component is neurovascular assessment, involving palpation of distal pulses (e.g., radial, dorsalis pedis), evaluation of capillary refill time, skin temperature and color, sensation to light touch, and motor strength, to detect vascular compromise or nerve injury that could lead to ischemia if untreated.[79] This examination must compare the injured limb to the contralateral side for baseline. Red flags during assessment demand urgent escalation, including open wounds exposing bone (indicating an open fracture with infection risk) or signs of acute compartment syndrome, such as pain disproportionate to the injury, worsening with passive stretch, progressive paresthesia or numbness, pallor, or tense compartments.[48] These findings, particularly in high-risk scenarios like tibial shaft fractures, signal potential limb-threatening emergencies requiring immediate surgical consultation.[80] Standardized clinical decision rules enhance efficiency and reduce unnecessary imaging. The Ottawa Ankle Rules, developed to identify malleolar or midfoot fractures after acute injury, involve checking for bony tenderness at specific sites (e.g., medial malleolus, base of fifth metatarsal) and inability to bear weight; their prospective validation showed near 100% sensitivity (pooled 97.6%) for clinically significant fractures, safely decreasing ankle radiographs by 30-35%.[81] Similar rules exist for the foot, emphasizing load-bearing capacity and tenderness to minimize radiation exposure without missing injuries. Limitations in history and physical examination arise in certain populations, where diagnostic accuracy diminishes. In polytrauma patients, the sensitivity of clinical findings for detecting significant fractures or injuries may be reduced due to distracting injuries, altered mental status, or systemic instability masking localized signs.[82] Similarly, obesity impairs palpation reliability and visualization, with studies indicating reduced accuracy of physical examination for certain orthopedic injuries such as shoulder assessments, often necessitating earlier reliance on adjunctive tests.[83]Imaging and Diagnostic Tests
X-rays remain the cornerstone of initial imaging for suspected bone fractures, typically obtained in two orthogonal views (anteroposterior and lateral) to assess alignment, displacement, and fracture characteristics.[84] This modality demonstrates high sensitivity, ranging from 90% to 95% for detecting most fractures in long bones and extremities, though it may miss subtle or nondisplaced fractures.[85] Advanced imaging techniques are employed when X-rays are inconclusive or for specific fracture types. Computed tomography (CT) provides detailed three-dimensional visualization, particularly useful for complex articular fractures, intra-articular involvement, or spinal fractures where precise assessment of fragment position is critical.[86] Magnetic resonance imaging (MRI) excels in identifying stress or occult fractures not visible on plain radiographs, offering superior soft tissue contrast to evaluate associated ligamentous or marrow edema.[87] Ultrasound serves as a portable, radiation-free option for detecting cortical disruptions in superficial bones, such as the forearm or tibia, and is especially valuable in pediatric or resource-limited settings for initial screening.[88] Laboratory tests complement imaging by assessing associated risks and healing potential. A complete blood count (CBC) helps identify infection or anemia that may complicate fractures, while coagulation profiles, including prothrombin time and partial thromboplastin time, are essential prior to surgical intervention to evaluate bleeding risks.[84] Bone turnover markers, such as bone-specific alkaline phosphatase, provide insights into fracture healing by measuring osteoblast activity, with elevated levels indicating active bone formation during the reparative phase.[89] The American College of Radiology (ACR) Appropriateness Criteria guide modality selection based on clinical suspicion and fracture location; for instance, radiography is rated as usually appropriate for initial evaluation of suspected extremity fractures, with MRI or CT recommended for occult or complex cases.[90] Recent advances as of 2025 include AI-assisted fracture detection algorithms applied to X-rays, which enhance diagnostic accuracy by automating identification of subtle fractures; these tools achieve specificities up to 98% when integrated with radiologist review, reducing missed diagnoses in emergency settings.[91]Classification
By Mechanism and Pattern
Bone fractures are systematically classified by mechanism and pattern to elucidate the injury dynamics, inform prognosis, and optimize treatment strategies, as these categories reflect the biomechanical forces involved and the resulting structural integrity of the bone.[92] This approach distinguishes fractures based on etiology—whether from acute trauma, underlying disease, or repetitive stress—and morphological features, such as the orientation and completeness of the break, which directly influence stability and healing potential.[9] Imaging modalities like X-rays are essential for accurately identifying these patterns, though clinical history provides initial clues to the mechanism.[93]Mechanism-Based Classification
Fractures arising from traumatic mechanisms occur when acute mechanical forces exceed the strength of normal bone, often subdivided into high-energy injuries from severe impacts like motor vehicle collisions or falls from height, and low-energy injuries from minor forces such as simple falls in the elderly.[9] High-energy traumatic fractures typically involve greater soft tissue damage and comminution, leading to higher complication rates, while low-energy ones are more common in osteoporotic bone but generally heal well with conservative management.[92] Pathologic fractures, in contrast, result from minimal or no trauma applied to bone already compromised by underlying conditions, such as metastatic cancer (e.g., from breast or lung primaries), primary bone tumors, or metabolic disorders like osteoporosis, which alter bone biomechanics and reduce healing potential— with union rates as low as 0% in cases of lung carcinoma metastases.[5] Stress fractures develop from repetitive cyclical loading on normal or weakened bone, causing microdamage accumulation and eventual incomplete or complete breaks; they are classified as fatigue fractures in healthy bone (e.g., from athletic overuse) or insufficiency fractures in abnormal bone (e.g., due to osteoporosis), with high-risk sites like the femoral neck requiring prompt intervention to prevent displacement.[94]Pattern-Based Classification
The morphological pattern of a fracture describes the configuration of the break, which correlates with the applied force and guides reduction techniques. Transverse fractures feature a straight line perpendicular to the bone's long axis, often from direct perpendicular loading, resulting in relatively stable fragments if nondisplaced.[9] Oblique fractures occur at an angle to the bone axis, typically from combined axial and bending forces, making them less stable and prone to shortening.[92] Spiral fractures exhibit a twisting pattern around the bone, indicative of rotational torque, and are common in torsional injuries like sports twists, often requiring surgical stabilization due to instability.[9] Comminuted fractures involve the bone shattering into three or more fragments, usually from high-energy impacts, complicating alignment and increasing infection risk if open.[92] Incomplete patterns predominate in children due to bone flexibility; greenstick fractures partially break one cortex while the other bends, resembling a snapped green twig, and torus (or buckle) fractures cause cortical buckling without full disruption, both often managed nonoperatively.[92] Impacted fractures, where one fragment is driven into the opposing end, are frequent in elderly patients with low-energy falls and may appear stable despite compression.[9]Displacement Characteristics
Displacement refers to malalignment of fracture fragments and is quantified to assess severity and need for intervention. Angulation describes an alteration in the bone's normal axis, where the distal fragment tilts relative to the proximal, potentially causing deformity if uncorrected—measured in degrees and direction (e.g., dorsal or volar).[95] Translation, or side-to-side shift, occurs when fragments move laterally relative to each other, expressed as a percentage of bone width (e.g., 50% overlap or complete override), and exceeding full width is termed "off-ended."[96] Rotation involves twisting of the distal fragment around the bone's long axis relative to the proximal, often subtle on imaging but detectable clinically through joint malalignment, and can impair function if significant, as in forearm fractures.[97]Soft Tissue Involvement in Open Fractures
Open fractures, where bone protrudes through the skin, are further classified by soft tissue injury using the Gustilo-Anderson system, which stratifies risk of infection and guides debridement urgency based on wound characteristics and contamination.[98]| Type | Description |
|---|---|
| I | Wound <1 cm long, clean or minimal contamination, low soft tissue damage.[98] |
| II | Wound 1–10 cm long, moderate soft tissue injury without extensive flaps, avulsions, or periosteal stripping.[98] |
| IIIA | Extensive laceration or high-energy trauma with adequate soft tissue coverage despite flaps or contamination.[98] |
| IIIB | Extensive soft tissue damage with periosteal stripping, bone exposure, and massive contamination, often requiring flap coverage.[98] |
| IIIC | Any open fracture with associated vascular injury requiring repair for limb viability.[98] |
By Location and Soft Tissue Involvement
Bone fractures are categorized by their anatomical location within the body, which directly impacts clinical management, potential complications, and healing outcomes due to variations in blood supply, mechanical stresses, and surrounding structures.[99] This approach highlights site-specific risks, such as neurovascular compromise in the extremities or instability in the axial skeleton. Additionally, the degree of associated soft tissue involvement is assessed separately, particularly for closed fractures, to guide surgical timing and infection risk.[100] Periprosthetic fractures, occurring adjacent to orthopedic implants, represent a distinct subset influenced by implant stability and bone quality.[101] In the upper extremity, clavicle fractures are among the most prevalent, comprising up to 10% of all fractures and being the most common in pediatric patients, with midshaft fractures accounting for approximately 80% of cases due to their central location under mechanical stress during falls.[102] These often result in cosmetic deformity but rarely cause long-term disability if managed conservatively. Proximal humerus fractures, particularly at the surgical neck, frequently occur in older adults from low-energy falls and involve the metaphyseal region just below the humeral head, potentially disrupting rotator cuff attachments and leading to shoulder instability.[103] Distal radius fractures are the most common upper extremity injury in adults over 50, with Colles' fractures featuring dorsal angulation and displacement of the distal fragment, typically from outstretched hand falls, while Smith's fractures exhibit volar displacement and are often linked to direct impacts or flexion forces.[47][104] Lower extremity fractures carry significant morbidity due to weight-bearing demands. Femur fractures are critical, with neck fractures common in the elderly from osteoporosis-related falls, disrupting the femoral head's blood supply and risking avascular necrosis, whereas shaft fractures arise from high-energy trauma and involve the diaphysis, often requiring intramedullary nailing for stabilization.[105][106] Tibia and fibula fractures, particularly bimalleolar ankle fractures, involve both the medial malleolus of the tibia and lateral malleolus of the fibula, compromising ankle mortise stability and frequently necessitating surgical fixation to prevent chronic instability or arthritis.[107] These distal fractures highlight the interplay between bone and ligamentous structures in the lower leg.[108] Axial skeleton fractures affect core stability and visceral protection. Spinal compression fractures primarily involve vertebral body collapse, most often in the thoracolumbar region due to osteoporosis or trauma, leading to height loss and potential kyphosis; they are graded by severity using the Genant system, where grade 1 indicates 20-25% height reduction and grade 3 exceeds 40%.[109] Pelvic fractures, including acetabular fractures, disrupt the hip socket formed by the ilium, ischium, and pubis, often from high-impact events, with implications for pelvic ring integrity and hip joint function; the Judet-Letournel classification delineates elementary patterns like posterior wall fractures from associated ones involving both columns.[110][111] Soft tissue involvement modifies fracture severity, especially in closed injuries, where the Tscherne classification grades damage from 0 to 3 based on trauma energy and tissue compromise. Grade 0 denotes minimal soft tissue injury from indirect forces with a simple fracture pattern, suitable for immediate fixation. Grade 1 involves superficial abrasions or contusions from indirect violence with moderate fracture severity. Grade 2 features deep contaminated abrasions and potential compartment syndrome from direct forces, requiring delayed intervention. Grade 3 encompasses high-energy crush injuries with extensive muscle damage, vascular issues, or nerve injury, often mandating staged reconstruction or amputation consideration.[100] This system underscores soft tissue's prognostic role beyond bony disruption.[112] Periprosthetic fractures occur near joint implants, complicating revision due to altered biomechanics and bone stock. In the hip, the Vancouver classification subtypes them as type A (trochanteric), type B (stem region: B1 with well-fixed prosthesis, B2 with loose stem but intact bone, B3 with loose stem and deficient bone), and type C (distal to prosthesis), guiding choices between fixation and revision arthroplasty.[113] These fractures, increasingly common with aging populations and implant longevity, emphasize preoperative implant assessment for optimal outcomes.[101]Management
Initial Stabilization and Pain Control
In the initial management of bone fractures, particularly in polytrauma scenarios, the Advanced Trauma Life Support (ATLS) protocol prioritizes the primary survey addressing airway, breathing, and circulation (ABCs) to stabilize the patient before focusing on fracture-specific interventions. Airway patency must be secured with cervical spine immobilization in blunt trauma cases to prevent secondary neurologic injury, while breathing is assessed to ensure oxygenation (target SpO₂ >93%) and ventilation, addressing issues like tension pneumothorax via needle decompression if present. Circulation involves controlling hemorrhage through direct pressure, tourniquets for extremity bleeding, or pelvic binders for unstable pelvic fractures, with permissive hypotension (systolic blood pressure 80-90 mmHg) until bleeding is controlled to minimize further blood loss.[114] Following ABC stabilization, immobilization is essential to reduce pain, prevent further soft tissue damage, and control bleeding. For upper extremity fractures such as those of the forearm, a sugar-tong splint is applied with the elbow at 90 degrees, forearm neutral, and wrist in slight extension to immobilize the radius, ulna, and wrist while allowing elbow flexion; this technique stabilizes without restricting circulation and is used temporarily until definitive care. In lower extremity injuries like mid-shaft femur fractures, traction splinting is recommended to align the fracture, alleviate pain, and improve alignment during transport, applied by securing an ankle hitch and providing inline traction counteracted by a pubic or ischial strap.[115][116] Pain management employs a multimodal approach to optimize relief while minimizing opioid use. Intravenous morphine, titrated at 0.05-0.1 mg/kg every 5-15 minutes to effect, is a cornerstone for severe pain in opioid-naive adults, often combined with intravenous acetaminophen (1 g every 6 hours) for synergistic analgesia without increasing adverse effects. Regional nerve blocks, such as femoral nerve blocks for femur fractures, provide targeted relief by interrupting sensory pathways, reducing systemic opioid requirements by up to 50% in acute settings. For open fractures, initial care includes urgent irrigation with at least 3 liters of normal saline to reduce bacterial load, followed by intravenous antibiotics like cefazolin 2 g within 1 hour of injury to cover gram-positive organisms and lower infection risk, and urgent surgical debridement within 24 hours to remove necrotic tissue and contaminants.[117][118][119] Ongoing monitoring for compartment syndrome is critical post-immobilization, involving serial clinical examinations every 1-2 hours in high-risk fractures (e.g., tibia or forearm) to detect early signs like disproportionate pain on passive stretch, tense swelling, or paresthesia. These exams guide the need for intracompartmental pressure measurement if clinical suspicion persists, as pressures exceeding 30 mmHg warrant emergent fasciotomy to prevent irreversible muscle necrosis.[48]Definitive Treatment Options
Definitive treatment for bone fractures aims to restore anatomical alignment, promote union, and enable functional recovery through either conservative or surgical approaches, selected based on fracture stability, displacement, and patient factors. Conservative management is preferred for stable, minimally displaced fractures, while surgical intervention is indicated for unstable or significantly displaced cases to prevent complications like malunion.[120][121] Conservative TreatmentsFor stable fractures, such as buckle (torus) fractures in children, immobilization with casting is the standard approach, allowing natural healing without surgical intervention. These compression injuries of the metaphysis are inherently stable and typically unite within 3-4 weeks under a short-arm cast or splint. Functional bracing, which permits controlled motion while providing support, is another option for select upper extremity fractures like distal radius buckle types, reducing stiffness compared to rigid casting.[122][123][124] Surgical Treatments
Open reduction and internal fixation (ORIF) involves surgical realignment of fracture fragments followed by stabilization using plates and screws, indicated for displaced fractures where closed methods fail to achieve alignment. This technique is widely used for periarticular fractures, such as those of the distal radius or proximal humerus, to restore joint congruity and prevent deformity. Intramedullary (IM) nailing is the gold standard for diaphyseal fractures of long bones like the femur and tibia, where a metal rod is inserted into the medullary canal to provide axial stability and load-sharing. For open or infected fractures, external fixation uses pins connected to an external frame to stabilize the bone temporarily or definitively, minimizing soft tissue disruption and infection risk in contaminated wounds.[125][126][127] Site-specific considerations guide treatment selection; for example, in elderly patients with displaced femoral neck fractures, arthroplasty (hemi- or total hip replacement) is often preferred over internal fixation to address comminution and reduce reoperation rates. Similarly, percutaneous pinning or screw fixation is recommended for scaphoid waist fractures to maintain alignment and promote vascularity in this avascular-prone bone.[128][129][130] Advanced Techniques
As of 2025, 3D-printed implants offer personalized solutions for complex fractures, enabling custom-fit titanium plates or scaffolds that match patient anatomy and enhance integration with host bone. Biologic augments, such as recombinant human bone morphogenetic protein (BMP-7 or BMP-2), are used adjunctively for non-unions, stimulating osteogenesis in recalcitrant cases with union rates exceeding 80% when combined with fixation.[131][132][133] Treatment decisions hinge on factors like displacement greater than 2 mm or instability, where conservative approaches risk malunion. Randomized controlled trials (RCTs) demonstrate that surgical fixation reduces malunion rates compared to conservative management, particularly in long bone shaft fractures, with operative groups showing up to 50% lower incidence in select pediatric and adult cohorts.[120][134][135]