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Radiology of Fracture Principles Suzanne O’Hagan 18 May 2012.

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Presentation on theme: "Radiology of Fracture Principles Suzanne O’Hagan 18 May 2012."— Presentation transcript:

1 Radiology of Fracture Principles Suzanne O’Hagan 18 May 2012

2 Radiographic Principles When analysing and ordering x-rays you should remember the rule of two’s: Two views. At 90 degrees, usually anterior-posterior and lateral. Two joints. The joints above and below. Two occasions. Some fractures are not easily visible immediately after trauma. Two limbs. If required for comparison. NB: In certain injuries, ‘special’ views are required. These include Scaphoid views, Skyline views for the patello- femoral compartment of the knee and Mortise view at the ankle.

3 Recognizing an acute fracture Disruption in the continuity of all or part of the cortex of a bone Complete:cortex broken through and through, traversing the width of the bone Incomplete: part of cortex fractured. Tend to occur in bones that are “softer” such as in children or in adults with bone-softening diseases such as osteomalacia or Paget’s disease Examples of incomplete fracture in children are: -Greenstick fracture, involves only one part of the cortex - Buckle fracture, compression of cortex

4 Greenstick fracture

5 Buckle fracture

6 Fracture Lines More lucent than other lines normally found in bones such as nutrient canals Abrupt discontinuity of the cortex Straighter in their course yet more acute in their angulation than naturally occurring lines such as epiphyseal plates The edges tend to be jagged and rough

7 Pitfalls Sesamoids – Bones that form in a tendon as it passes over a joint. The patella is the largest. Accessory ossicles – These are accessory epiphyseal or apophyseal ossification centres that do not fuse with the parent bone Unlike fractures these small bones are corticated and their edges are usually smooth Sesamoids and accessory ossicles are usually bilateral and at anatomically predictable sites Old, unhealed fracture fragments – Can be confused with new fractures

8 Sesamoid bones at joints Knee – the patella (within the quadriceps tendon) Hand – two sesamoid bones commonly found in the distal portions of the first metacarpal bone (within the tendons of adductor pollicis and flexor pollicisbrevis); also distal portion of second metacarpal bone Wrist – the pisiform within the flexor carpiulnaris tendon Foot – first metatarsal bone has two sesamoids at its connection to the big toe, within the tendon of flexor hallucisbrevis (sometimes only a single sesamoid)

9 Accessory Ossicles The process of ossification progresses from a primary ossification centre, until the bone is completely ossified. Irregularly shaped bones such as the tarsal bones may develop a secondary centre and in some individuals complete ossification does not occur. The secondary centre remains separate from the rest of the bone, forming an accessory ossicle. Os trigonum – the separated posterolateral tubercle of the talus. Os tibiale externum (accessory navicular) – located posteromedial aspect of navicular where posterior tibialis tendon inserts

10 Accessory ossicles Os Peroneum In peroneusbrevis tendon Os fabella Posterior to the lateral condyle of the femur. It exists in the location of the lateral head of gastrocnemius tendon. Many more…

11 Describing fractures 4 major parameters – Number of fragments – Direction of fracture line – Relationship of fragments to each other – Communication of the fracture with the outside atmosphere

12 Number of fracture fragments 2 fragments = simple fracture >2 = comminuted fracture – Segmental fracture A portion of the shaft exists as an isolated fragment – Butterfly fragment Central fragment has a triangular shape

13 Direction of fracture lines Transverse: Fracture line perpendicular to long axis of bone (perpendicular force) Oblique: Fracture line diagonal relative to long axis (force usually applied along same direction as long axis) Spiral: Caused by a twisting force, usually unstable and often associated with soft tissue injury

14 Relationship of Fragments to each other 1. Displacement 2. Angulation 3. Shortening 4. Rotation By convention, describe the relationship of the distal fragment relative to theproximal fragment

15 Displacement Amount by which the distal fragment is offset, front to back and side to side, from the proximal fragment Described in terms of percent or fractions (e.g. 50% the width of the shaft or ½ the width of the shaft of the proximal fragment)

16 Angulation Angle between the distal and proximal fragments Described in degrees and by position – State direction of distal bone Superior, inferior, anterior, posterior, medial, lateral, volar, dorsal – State degree of angulation relative to proximal bone – Medial (varus), Lateral (valgus)

17 Colles fracture Transverse fracture of distal radius 2.5cm proximal to radiocarpal joint Dorsal displacement and volar angulation

18 Shortening How much, if any, overlap there is of the ends of the fracture fragments How much shorter the fractured bone is than it would be had it not been fractured Shortening is described in centimetres

19 Midshaft femur fracture

20 Distraction and Impaction Distraction – Increase in overall bone length Impaction – Shortening with no loss of bone alignment

21 Rotation

22 Unusual Almost always involving the long bones Describes the orientation of the joint at one end relative to the orientation of the joint at the other end of the fractured bone Eg proximal tibia oriented in frontal projection while distal tibia and ankle oriented laterally Both the joint above and below the fracture need to be included to appreciate rotation

23 Relationship of Fracture to Atmosphere Closed – More common – No communication Open/compound – Communication Best diagnosed clinically

24 Avulsion fractures Common mechanism of fracture production Avulsed fragment is pulled from its parent bone by contraction of a tendon or ligament More common in young athletes Derive many of their names from athletic activity e.g. dancer’s fracture, skier’s fracture, sprinter’s fracture Occur in anatomically predictable locations where tendons are known to insert May heal with exuberant callous formation Some may resemble a neoplastic or infectious process Some may have an aggressive appearance that may include areas of mixed lysis and sclerosis The appearance depends on whether acute, subacute or chronic

25 Avulsion fracture lesser trochanter (iliopsoas) Avulsion fracture ischialtuberosity (hamstrings) Avulsion Fractures: common in the pelvis In the pelvis, the newly formed secondary centers of ossification, the apophyses, are most likely to avulse· Apophyses tend to form at the time of puberty = time of pelvic avulsions

26 Sites and Insertions

27 Dancer fracture

28 Don’t confuse with Jone’s Fracture Jones fracture involves a fracture at the base of fifth metatarsal at metaphyseal- diaphyseal junction A Jones fracture is located within 1.5 cm distal to tuberosity of 5th metatarsal Avulsion fracture more common and affects the 5th metatarsal styloid process proximally.

29 Osgood Schlatter Caused by stress on the patellar tendon Patellar tendon attaches the quadriceps muscle to the tibial tuberosity Adolescent growth spurt, repeated stress from quadriceps contraction is transmitted through the tibial tuberosity Causes multiple subacute avulsion fractures with inflammation along the tendon leading to excess bone grwoth in the tuberosity

30 SALTER-HARRIS FRACTURES Epiphyseal plate fractures in children In growing bone, the hypertrophic zone in the growth plate (epiphyseal plate or physis) is most vulnerable to shearing injuries Account for as many as 30% of childhood fractures SH classification helps determine treatment and predict complications Represent a spectrum of accidental injuries in children

31 SALTER HARRIS CLASSIFICATION Epiphyseal plate only Epiphyseal plate + metaphysis Epiphyseal plate + epiphysis Compression fracture epiphyseal plate Epiphyseal plate + epiphysis + metaphysis

32 Prognosis Types I and II heal well Type III fractures can develop arthritic changes or asymmetric growth plate fusion Types IV and V are more likely to develop early fusion of the growth plate with angular deformities and shortening of that bone

33 Type I: Fractures of the epiphyseal plate alone Difficult to detect without comparison views SCFE is a manifestation of a SH I injury – Tall, heavy teenage boys – Bilateral in 25% – Can result in avascular necrosis due to interrupted blood supply in 15%

34 Salter Harris I “widening of the growth plate” Slipped Capital Femoral Epiphysis

35 Salter Harris I

36 Type II: Fracture of the epiphyseal plate and fracture of metaphysis Most common (75%) Seen especially in the distal radius

37 Salter Harris II Distal radius Assoc ulnar fracture “above the growth plate”

38 Type III: Fracture of the epiphyseal plate and epiphsysis Longitudinal fracture through epiphysis itself; fracture invariably enters the joint space and fractures the articular cartilage Risk of osteoarthritis later in life Can result in premature and asymmetric fusion of the growth plate with subsequent deformity

39 Salter Harris III “below the growth plate”

40 Type IV: Fracture of epiphysis and metaphysis through the epiphyseal plate Poorer prognosis – premature and possibly asymmetric closure of growth plate May lead to differences in limb length, angular deformities and secondary OA

41 Salter Harris IV “through the growth plate”

42 Salter Harris IV

43 Salter Harris V Rare Associated with vascular injury Almost always result in growth impairment through early focal fusion of the growth plate Most common in the distal femur, proximal tibia and distal tibia Difficult to diagnose on conventional radiographs until later when they complicate

44 Salter Harris V LeftRight

45 Non-accidental injury patterns Metaphyseal corner fractures Rib fractures – Especially multiple and posterior Head injuries – Skull fractures tend to be bilateral, comminuted and cross suture lines (associated subdurals, SAH, cerebral contusion)

46 CML: Classic Metaphyseal Lesion Virtually pathognomonic of abuse series of microfractures across the metaphysis the fracture line is oriented essentially parallel to the physis, although it may not travel the entire width of the bone precipitating force is a shearing injury across the bone end, the result of horizontal motion across the metaphysis, therefore not a feature of falls or blunt trauma force is generated by manual to-and-fro manipulation of the extremities (eg, holding and shaking an infant by the feet or hands or shaking the infant while he is held around the chest) CML is seen almost exclusively in children less than 2 years of age

47 CML: Corner or Bucket Handle Fracture

48 Stress Fracture Bone subjected to repeated stretching and compressive forces Numerous microfractures Conventional radiographs may initially appear normal in up to 85% Fracture may not be diagnosable until after periosteal new bone formation or healing occurs Bone scans or MRI will usually be positive earlier Common locations include the shafts of long bones, the calcaneus and the 2 nd and 3 rd metatarsals

49 Stress Fractures

50 5 MOST COMMON EPONYMS Colle’s Smith’s Jones Boxer’s March 3 in the hand, 2 in the foot

51 Colle’s Fracture Colles' fracture is a fracture of the distal metaphysis of the radius with dorsal displacement and volar angulation leading to a ’dinner fork deformity’. Colles fractures are seen more frequently with advancing age and in women with osteoporosis.

52 Smith’s Fracture Reversed Colle’s Occurs in younger patients Results from high energy trauma on the volar flexed wrist Volar displacement and dorsal angulation Intra-articular extension more common

53 Jone’s Fracture Transverse fracture of 5 th metatarsal 1.5cm from its base Caused by plantar flexion of the foot and inversion of the ankle Less common than avulsion fracture

54 Boxer’s Fracture Fracture of head of 5 th metacarpal with palmar angulation Usually results from punching a person or wall

55 March Fracture Type of stress fracture to the foot Usually shafts of 2 nd or 3 rd metatarsals

56 EASILY MISSED FRACTURES Scaphoid fractures Buckle fractures Radial head fractures Supracondylar fractures Posterior disclocation of the shoulder Hip fractures in the elderly

57 Scaphoid Fracture Tenderness in anatomical snuff box after fall on outstretched hand Hairline thin radiolucencies on scaphoid views (ulnar deviation of wrist)

58 Radial Head Fracture Common in adults Look for a positive fat pad sign: – Posterior fat pad usually invisible – Crescenticlucency of fat along the posterior aspect of the distal humerus is produced by normally invisible fat that is lifted away from the bone by swelling of the joint capsule due to haemarthrosis

59 Radial head fracture

60 Supracondylar Fracture Most common fracture of the elbow in a child Most produce posterior displacement of the humerus True lateral, anterior humeral line should bisect the middle third of the ossification centre of capitellum In most supracondylars, this line passes anterior to its normal location

61 Anterior humeral line

62 Positive Fat Pad Sign

63 Posterior Dislocation of the Shoulder “Y” view (oblique view of the shoulder), head will lie lateral to the glenoid in posterior dislocation Frontal: Humeral head fixed in internal rotation, resembles a light bulb

64 Hip Fractures in the Elderly Frequently related to osteoporosis Take x-rays with leg in internal rotation to display the neck in profile Look for angulation of the cortex and zones of increased density (impaction) Look for secondary signs MRI or bone scan will be required when indicated

65 Secondary signs of fractures Soft tissue swelling Disappearance of normal fat stripes Joint effusion Periosteal reaction (late)

66 FRACTURE HEALING Determined by many factors – Age of patient – Fracture site – Position of fracture fragments – Degree of immobilization – Blood supply – Mineralisation of bone – Medication

67 FRACTURE HEALING PROCESS Immediate: Haemorrhage into fracture site First few weeks: Osteoclasts act to remove diseased bone (fracture line may widen) Next few weeks: New bone (callus) begins to fill the fracture defect. 8 – 12 weeks: Remodelling – Mechanical forces adjust bone back to its original shape – Fast in children, slow in adults

68 COMPLICATIONS OF FRACTURE HEALING Delayed union – Fracture does not heal in expected time – Most will eventually heal if immobilisation extended Malunion – Healing occurs in a mechanically or cosmetically unacceptable position Non-union – Implies that fracture healing will never occur – Smooth, sclerotic margins with distraction of the fracture fragments – Pseudarthrosis may form – Motion at the fracture site may be demonstrated on stress views or with fluoroscopy

69 Fracture healing complications

70 Role of CT and MRI CT usually requested to obtain further detail for surgical planning especially in fractures of: – Tibial plateau – Acetabulum – Ankle (?trimalleolar) – Calcaneus – Cervical spine MRI usually cases of doubt to detect bone marrow oedema particularly in occult fractures of: – Hip – Scaphoid – Stress fractures eg tibia, metatarsal Also gives additional information regarding the soft tissue components Bone scan low specificity

71 Intertrochanteric fracture Tibial plateau fracture T1WI - stress fracture 2 nd metatarsal

72 Conclusion Radiological interpretation of fractures is a huge topic. Classifications are detailed and can sometimes be clumsy. A good starting point is to be able to describe a fracture correctly using the principles discussed in this lecture.

73 References Herring, W. Learning Radiology: Recognizing the Basics 2 nd Ed p232. Greenspan, A. Orthopaedic Imaging: A Practical Approach. Chapter 4: Radiologic Evaluation of Trauma Thompson, JC. Netters Concise Orthopaedic Anatomy ures


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