Approach to Radiographic Evaluation of Fractures Sehar Resad, MS4 Ashley Davidoff, MD Definition
A fracture is defined as the disruption of the integrity of living bone. A fracture is caused when the force applied to the bone is greater than the integrity of the bone. Overview
Describing fractures: • Open vs Closed • Location • What bone? • Where on the bone? • Type of Fracture • Degree • Complete vs incomplete • Articular involvement • Comminution & Pattern • Intrinsic bone quality • Displacement, alignment Courtesy of GW EMED Educational Corner Open vs Closed L D
A C I D Open Fracture (aka Compound)
Open fracture defined as fracture that causes violation of the skin. They are often difficult to assess on radiograph.
AP radiograph of the right femur shows a femur fracture (red arrow) classified as open as evidenced by proximal fragment breaching skin surface (yellow dotted line).
Case courtesy of Souza C. Radiopaedia.org O Location D
Articular Involvement C I D Location
• Which bone? • Which part of the bone? • Epiphysis • Intraarticular • Extraarticular • Metaphysis • Physis • Diaphysis • Proximal • Midshaft • Distal
Image courtesy of scienceagogo.com Long Bone Anatomy
• Epiphysis – end of long bone • Intraarticular fracture: extends into articulating surface of joint • Extraarticular: no extension into joint • Metaphysis – neck of long bone, contains growth plate • Diaphysis – shaft of long bone • Further defined by location using proximal, midshaft, or distal Radiograph of Metaphyseal & Epiphyseal Fracture with Intraarticular Extension of Distal Radius
AP (a.) and lateral (b.) radiographs of the left wrist in a skeletally mature individual showing metaphyseal fracture (yellow arrow) and epiphyseal fracture (blue arrow) with intraarticular extension (red arrow).
Case courtesy of Di Muzio, B. Radiopaedia.org Radiographs of Proximal, Midshaft, and Distal Diaphyseal Fractures of the Humerus
Variations in location of diaphyseal fractures of the humerus. AP radiograph of left shoulder (a.) shows a proximal humeral shaft fracture, AP radiograph of the left humerus (b.) shows a midshaft fracture, and AP radiograph of right humerus (c.) shows a distal humeral shaft fracture.
Cases courtesy of: (a.) Davidson, L. Radiopaedia.org (b.) Knipe, H. Radiopaedia.org (c.) Weatherford, B. Orthobullets.com Radiograph of Comminuted Proximal Radius Fracture with Intraarticular Extension
Oblique (a&b) and lateral (c&d) radiographs of the proximal radius of a 38 y.o. female following blunt trauma show a comminuted fracture of the head of the radius with involvement of the joint surface (white arrow). A transverse fracture at the junction of the diaphysis with the metaphysic is seen on the lateral examination (red arrow). An avulsed fragment is shown by the green arrow, easily seen in b, but barely visible in d. Radiograph of Wrist with Subtle Intraarticular Distal Radius Fracture
Oblique view of the distal radius, with magnification (b&c), shows a simple fracture of the distal radius with involvement of the joint surface (white arrow c). Long Bone Anatomy – Children
• Physis = growth plate • Translucent, cartilaginous disc separating the epiphysis from the metaphysis • Responsible for longitudinal growth of long bones • Physeal closure occurs at different times in different long bones • Salter-Harris Classification
Courtesy of OrthoGate Remembering Salter Harris: SALTR
I: Straight across II: Above III: Lower (beLow) IV: Through R: Rammed (cRushed)
Courtesy of Int. Emergency Medicine Education Project Radiographic Assessment of Salter Harris Classification of Physeal Injuries of the Distal Radius
AP radiograph of the right wrist in 10 y.o. child demonstrating the Salter Harris Classification of physeal injuries. SH I fracture is a fracture that involves the epiphyseal plate only while SH II involves the epiphyseal plate and the epiphysis, with SH III involving the metaphysis , while SH IV involves the metaphysis, epiphysis, and epiphyseal plate and SH V is a compression fraction of the epiphyseal plate. O L Degree (Complete vs Incomplete)
A Comminution & Pattern I D Type of Fracture
• Complete = all the way through • Incomplete* = whole cortex is the bone not disrupted • Simple: 2 fragments • Torus/Buckle • Transverse • Bowing • Oblique • Greenstick • Avulsion • Spiral *more common in children • Segmental • Comminuted: >2 fragments • Butterfly Fragment Complete Simple: Transverse Fracture
AP view of the left ankle (a.) with magnified view of the fibula (b.) shows a transverse fracture (blue arrows) of the distal fibula. This fracture is classified as complete since the fracture line extends all the way across the bone (yellow dotted lines) and simple as there are only two resultant fragments. The red arrow indicates the direction of force sustained perpendicular to the fibula resulting in this fracture pattern. Complete Simple: Oblique Fracture
AP radiograph of the right hand shows a simple oblique fracture of the shaft of the 4th proximal phalanx. The fracture line is overlaid in black in image b. Complete Simple: Avulsion Fracture
Lateral radiograph of the elbow (a), magnified in (b), shows a small fragment posterior to the olecranon of the ulna (blue arrow) representing an avulsion fracture likely from traction at the insertion of the triceps. The pulling force on the bone is in the direction of the triceps contraction (red arrow figure b). Complete: Spiral Fracture
AP (a.) and lateral (b.) radiograph of the right tibia and fibula in a skeletally immature patient (as evident by presence of open physes (yellow arrows)) showing a spiral fracture of the distal tibia (white arrows). Red arrows (c.) show force sustained with rotational component with fracture line overlaid by blue dotted line.
Case courtesy of Bickle I. Radiopaedia.org Complete: Segmental Fracture
A segmental fracture is defined as a fracture composed of at least two fracture lines that together isolate a segment of bone.
AP radiograph of the right femur shows a proximal oblique fracture (red arrow) and midshaft transverse fracture (blue arrow) with resultant isolation of a portion of the femoral diaphysis (yellow overlay).
Case courtesy of Samir B. Radiopaedia.org Complete: Comminuted Fracture
Oblique radiograph of the tibia and fibula showing markedly comminuted fractures of the proximal and midshaft of the tibia and fibula (red arrows) in a patient who sustained multiple gunshot wounds. Scattered metallic bullet shrapnel throughout the fracture site is also seen (yellow arrows).
Case courtesy of Sklaski M. Radiopaedia.org Complete: Comminuted Butterfly Fragment
AP radiograph of the left tibia and fibula show transverse oblique comminuted fracture (blue arrows) with associated butterfly fragment (blue overlay) of the midshaft tibia. Figure b. illustrates how this fracture got its name. Oblique comminuted fracture also present at the proximal third of the fibular diaphysis (yellow arrows).
Case courtesy of Sklaski M. Radiopaedia.org Incomplete Fractures
Schematic of the basic interaction of bone with sudden force (red arrows) in the pediatric population. Softer bone is more elastic. If the force is an impaction force such as a fall on the outstretched arm a wrinkle, buckle or torus fracture ensues (a). In the bending or bumper type force (b and c) bowing of the bone (b) or incomplete fracture with a “T” shaped configuration ensues (c), with at least part of the fracture line occurring on the long axis of the bone. Incomplete: Torus/Buckle Fracture
AP (a&b) and lateral (c&d) radiographs of the right arm show a buckle or torus fracture (white arrows) of the distal radius in a skeletally immature patient. “Torus” is derived from the Latin word 'tori' which means swelling or protuberance. Incomplete: Bowing Fracture
AP radiograph of the left arm in a skeletally immature patient (a) shows a bowing deformity fracture of the shaft of both the radius and ulna, overlaid in green (b). Bowing fractures are caused by a force (red arrow) that causes a bending deformity without a grossly visible fracture or macroscopic break of the cortex as softer bones of children allow the bone to yield to force without fracturing. Image c shows equivalent injury to a young branch that has been subjected to a bending force. Incomplete: Greenstick Fracture
AP radiograph of left arm (b&c) showing an incomplete fracture (yellow arrow) on the side distal the deforming force (red arrow). The fracture line shows both horizontal and vertical components to the greenstick fracture (overlaid in black in c). Figure a. shows the incomplete fracture of a young branch (greenstick) that has been subjected to a bending force that was able to overcome the resiliency of the branch by which the greenstick fracture gets its name. O L D
A C I Displacement/alignment/angulation/rotation Alignment
• Describes the relationship of the longitudinal axis of one fragment to another
• Described using: • Translation • Medial vs lateral (coronal plane) • Dorsal vs volar (sagittal plane)
a. Normal bone b. Anatomically aligned fracture c. Fracture that is translated ~50% d. Fracture that is completely translated (>100%) Alignment - Maintained
AP radiograph of the right 5th metatarsal shows a simple transverse fracture (black line overlaid in b) with maintenance of anatomical alignment of the component parts. Alignment - Translation
AP (a.) and lateral (b) radiographs of the distal tibia and fibula show a transverse midshaft tibial fracture (red arrow) with lateral and dorsal translation (white arrows) of the distal segment ~50% of the shaft width.
Case courtesy of van der Plas A. Startradiology.com Displacement
• Describes the malalignment of two fracture fragments where there is loss of cortical continuity
• Described using: • Angulation • Varus vs. Valgus • Dorsal vs. Ventral • Rotation • Length • Distraction vs impaction Displacement: Angulation
• AP/Coronal Plane • Varus = (Apex Lateral) • Distal fragment is more medial than it should be • Valgus (Apex Medial) • Distal fragment is more lateral than it should be Special Vocabulary: Forearm • Lateral/Sagittal Plane & Hand • Anterior Angulation (Apex Posterior) • Distal fragment more anterior than it • Lateral = Radial should be • Medial = Ulnar • Posterior Angulation (Apex Anterior) • Anterior = Volar / Palmar • Distal fragment more posterior it should be • Posterior = Dorsal Displacement – Varus Angulation
AP radiograph of the left humerus shows an oblique midshaft fracture of the humerus (green arrow). The distal segment (blue asterisk) is more medial (white arrow) than it should be in relation to the proximal segment (dotted red line), indicating varus angulation. Overlay in image b shows apex of angulation located laterally (intersection of yellow lines). Displacement – Valgus Angulation
AP radiograph of the right tibia and fibula shows an oblique midshaft fracture of the tibia (green arrow) and transverse midshaft fracture of the fibula (orange arrow). In both, the distal segment (blue asterisk) is more lateral (white arrow) than it should be in relation to the proximal segment (dotted red line), indicating valgus angulation. Overlay in image b shows apex of angulation located medially (intersection of yellow lines). Displacement – Anterior/Ventral Angulation
Lateral radiograph of the wrist shows a distal radius fracture with ventral (anterior) angulation of the distal segment (red line in figure b). This creates an apex dorsally (posteriorly) (intersection of green & red lines in image b). This is also known as a “Smith fracture.”
Case courtesy of Gerstenmaier FJ. Radiopaedia.org Displacement – Posterior/Dorsal Angulation
Lateral radiograph of the wrist shows a distal radius fracture (yellow arrow) with dorsal (posterior) angulation of the distal segment (red line in image b). This creates an apex ventrally (anteriorly) (intersection of green & red lines in image b). This is also known as a “Colle’s fracture.” Displacement – Rotation
AP (a.) and lateral (b.) radiographs of the tibia and fibula show a spiral fracture of the distal tibia diaphysis (blue arrow) with 90o of lateral rotation of the distal segment. This is noted by the lateral projection of the ankle on the AP image (a.) and frontal projection of the ankle on the lateral image (b.) (red arrows). There is also a spiral fracture of the proximal fibula diaphysis, which is more apparent on the AP radiograph (green arrow).
Case courtesy of Hacking C. Radiopaedia.org Displacement: Length
• Impaction • Occurs when one component of a fracture is driven into the second part • Causes foreshortening of the bone • Shortening • Bayonet Apposition • Two bone fragments are aligned side-by-side rather than in end-to-end contact • Distraction • Is the longitudinal separation of the fragments • Overall lengthening of the bone Displacement – Impaction
AP (a) and oblique (b) radiographs of the distal radius and ulna show a simple transverse fracture of the distal ulna diaphysis (red arrow). Impaction of the fracture (white arrow) is evident by the ulnar shortening in relation to the radius at the wrist joint. Displacement – Bayonet Apposition
AP (a.) and lateral (b.) radiographs of the distal radius and ulna in a skeletally immature individual show simple transverse fractures of the distal radius (red arrow) and ulna (blue arrow). There is evidence of shortening in the setting of Bayonet apposition of the radial fragments (overlaid in b.). There is also dorsal angulation (apex volar) of the distal ulna (green line figure b). Case courtesy of Royal Children’s Hospital of Melbourne. rch.org.au/clinicalguide. Displacement – Distraction
Lateral radiograph of the knee shows a transverse fracture of the patella with apical distraction of the proximal segment (white arrow) due to the pulling force of the quadriceps tendon. There is no residual contact between fracture fragments (red line).
Case courtesy of Samir B. Radiopaedia.org O L D
A C Intrinsic bone quality D Intrinsic Bone Quality
• Osteopenia → Osteoporosis: Decreased bone density • Loss of normal pattern of strong interconnected plates of bone with remaining bone having a weaker rod- like structure. • Osteopetrosis: Increased bone density • Aka “stone bone” Image courtesy of Rockville. Office of the Surgeon General., 2004. • Rare inherited disorder where ones https://www.ncbi.nlm.nih.gov/books/NBK45504/figure/ch2.f5/ become sclerotic and thick, but their abnormal structure actually causes them to be weak and brittle. Osteoporosis
AP radiographs of the ankle in a normal 21 y.o. male (a) and 81 y.o. osteoporotic female (b) demonstrating the prominent trabeculae of the bone (blue arrow) and the overall density of the bone is decreased in the osteoporotic patient. Osteopetrosis
AP radiographs of the left hand (a), foot (b), and shoulder (c) in a patient with family history of osteopetrosis show diffuse areas of increased bone density (red arrows) indicating bony sclerosis, with particular involvement of the entire left proximal humerus (blue asterisk). Case courtesy of Patel MS. Radiopaedia.org Putting it all together! What bone? Where on the bone? Type of fracture? Alignment? Displacement? AP radiograph of the left hip shows a simple oblique fracture of the left proximal diaphysis of the femur with medial angulation of the distal segment (mild varus defomity).
• Simple oblique fracture = red arrow • Medial angulation = white arrow in relation to dotted blue line • Varus deformity = green line What bone? Where on the bone? Type of fracture? Alignment? Displacement? CT of the ankle in the sagittal plane shows a simple oblique fracture of the distal tibia metaphysis, physis, and epiphysis in a skeletally immature individual. The fracture line extends intraarticularly into the ankle joint. This is classified as a Salter-Harris IV. Anatomic alignment is maintained.
• Simple oblique fracture = black line • Open physis = yellow arrow • Metaphyseal component = blue overlay • Epiphyseal component = green overlay • Intraarticular extension = red line
Case courtesy of St. Vincent’s University Hospital Department of Radiology. Svuhradiology.ie. What bone? Where on the bone? Type of fracture? Alignment? Displacement? AP and oblique radiographs of the left hand shows a simple transverse midshaft fracture of the second metacarpal. On the AP view, the fracture appears in alignment with minimal impaction. On the oblique view, there is volar angulation of of the distal segment (apex dorsal).
• Transvers fracture = black line • Volar angulation = white arrow • Impaction = white arrow in relation to dotted blue line • Apex volar = intersection of green lines Special Fracture Considerations: Pathological
• Fractures that occur in abnormal bone and occur spontaneously or following minor trauma that would not otherwise fracture biomechanically normal bone. • Tumors • Primary • Secondary (metastatic) • Bone cyst • Metabolic • Osteoporosis • Paget’s disease • Hyperparathyroidism Pathologic Fracture in Setting of simple (Unicameral) Bone Cyst AP radiograph of the right humerus (a.), with magnification (b.), shows a sharply demarcated lytic lesion in the proximal humerus causing cortical expansion and thinning (blue overlay in b). There is associated pathological fracture (red arrow) with fracture fragment in dependent portion of cyst (green arrow). This is known as a “fallen fragment sign” and is highly associated with unicameral bone cysts. Case courtesy of Mudgal P. Radiopaedia.org Special Fracture Considerations: Stress Fractures
• Fractures that occur in the bone due to a mismatch of bone strength and chronic mechanical stress placed upon the bone – common in athletes • Plain radiographs • Poor sensitivity • Positive findings may take months • “Grey cortex sign” • Increasing sclerosis or cortical thickening along the fracture site • Periosteal reaction/elevation • Nuclear Medicine • Bone scans can show evidence of stress fracture within a few days of symptom onset • MRI • Most sensitive • Findings • Periosteal or adjacent soft tissue edema • Band-like bone marrow edema • T1 hypointense fracture line evident in high-grade injury Radiographic Findings Suggestive of Stress Fractures
AP radiograph of the tibia (b.) shows periosteal elevation along the anterolateral cortex of the mid-tibia (arrows). Close up of radiograph of the mid-tibia (a.) shows mature periosteal (straight arrow) and endosteal reactive changes (curved arrow) associated with focal areas of osteopenia in the cortex, known as a “grey cortex sign.”
Case courtesy of Musculoskeletalkey.com Nuclear Medicine Bone Scan of Tibial Shaft Stress Fracture b. Bone scan from a 19 y.o. male in his fourth week of basic training presenting with one week history of right anterior shin pain. Initial radiographs at presentation showed not abnormality. Bone scan shows focal linear increased up-take in the proximal one third in the tibial diaphysis (red arrow). Stress fractures on bone scintigraphy appear as foci of increased radioisotope activity ('hot spot') due to increased bone turnover at the site of new bone formation.
Case courtesy of Vawter KW. Medpix.nlm.nih.gov MRI of Calcaneal Stress Fractureb.
MRI of the right heel in a 30 y.o. male long-distance runner. T1 weighted image (a.) demonstrates dark fracture line (red arrow) with decreased signal suggesting bone marrow edema (red asterisks). T2 weighted image demonstrates fracture line (red arrow) and increased signal (red asterisks). Case courtesy of Williams P. Medpix.nlm.nih.gov References
• Image References – authors noted on slides • Dr. Ashley Davidoff, TheCommonVein.net • Radiopaedia.org • Orthobullets.com • Medpix.nlm.nih.gov • Musculoskeletalkey.com • Startradiology.com • Other Journals and Texts • Bolander S. A systematic approach to describing fractures. JAAPA. 2019 May;32(5):23-29. doi: 10.1097/01.JAA.0000554731.08786.ba. Erratum in: JAAPA. 2019 Jul;32(7):1. PMID: 30969188. • Hacking, C. (n.d.). Describing a fracture (an approach): Radiology Reference Article. Retrieved November 10, 2020, from https://radiopaedia.org/articles/describing-a-fracture-an-approach?lang=us • Meinberg E, Agel J, Roberts C, et al. Fracture and Dislocation Classification Compendium–2018, Journal of Orthopaedic Trauma. Volume 32: Number 1; Supplement, January 2018. • Themes, U. (2017, January 07). An introduction to fractures. Retrieved November 10, 2020, from https://musculoskeletalkey.com/an-introduction-to-fractures/