Radiology Of Fractures And Fracture Healing

sihirlifil's version from 2017-09-02 14:16


Question Answer
Causes for bone fractures (7)Abnormal metabolism
Abnormal structure
Trauma stresses bone beyond structural capacity
Weakened by other process
Sequel of stress protection (weakened bone adjacent to orthopedic plate)
Fatigue from repeated stress (e.g. metacarpals/tarsals in racing greyhounds & horses)
Defect in bone from biopsy, surgery, after plate removal
Example of indirect traumaAvulsion
Pathological fractures can occur secondary to (7)Neoplasia
Bone cyst
Diffuse osteopenia (2ry hyperPTH)
Brittle or fragile bone (Osteoperosis, osteogenesis imperfecta)
Incomplete ossification of humeral condyle
Empty screw hole from internal fixation device
Radiographic signs of fracturesDisruption of normal shape of bone, cortex, trabecular pattern; radiolucent fracture lines
What must you be careful of when you think you see a fracture line?Can be mimicked by other things!
Other things that can look like fracture lines:Nutrient foramina
Overlying fascial plane fat, skin
Gas in fascial planes (open fractures)
Normal growth plates
Skull sutures
Mach lines
Grid line artifact
What is a Mach line?Lucent lines above contour of bone when they overlap. Creates optical illusion, can be mistaken for fissures or fractures
Fracture lines can only be seen if they are ___ to the x-ray beamParallel
If a limb is painful during the healing process, what might follow-up radiographs show?Disuse osteopenia, muscle atrophy
What kinds of fracture may increase the opacity of the cortex and medulla?Folding fracture
Overriding fracture ends
Small bone fragments =Chip fracture
Chip fractures may look like?Additional centers of ossification
Multipartite sesamoid bones
Dirt, debris in soft tissue
What should you do if you suspect a chip fracture?Radiograph contralateral limb to compare
What materials could be present in a compound open fracture?Ballistics, FB, gas
Classification of fractures: (14)Closed vs open/compound
Single or comminuted
Transverse vs oblique, spiral, longitudinal, or irregular
Complete vs incomplete
Articular vs non-articular
Comminuted fracture =3 or more fragments
Segmental fracture =2 or more fracture lines in the same bone
Complete fracture =Both cortices / entire width of bone
Incomplete fracture =Only 1 cortex
Examples of incomplete fractureGreenstick (Convex side of cortex, periosteum intact)
Torus (concave side of cortex)
Chip fracture =1 or no articular margin
Slab fracture =2 articulations (e.g. carpal, tarsal)
Articular fracture =within limits of joint capsule
Avulsion fracture =Traction by soft tissue attachment (apophysis)
Fatigue/stress fracture =One cortex, repetitive minor trauma
Impaction/compression fracture =Shortening due to stress along length, one fragment into another (especially vertebrae)
Fracture (sub)luxation =Associated soft tissue injury leads to joint instability/displacement
Salter-Harris fracture =Unfused growth plates involved (shortening or abnormal angulation)
(Examples of location for avulsion fractures)Medial malleolus of tibia (medial collateral ligament involvement)
Supraglenoid tubercle of scapula (biceps brachii tendon)
Salter-Harris Type ISeparation at the level of physis, may move in horizontal plane
‘Slipped epiphysis’ =Salter-Harris Type I, when physis moves in horizontal plane
Salter-Harris Type IIFracture involves physis and metaphysis
Salter-Harris Type IIIFracture involves physis and epiphysis
Salver-Harris Type IVFracture involves physis, metaphysis and epiphasis and the joint
Salter-Harris Type VCrushed / compressed physis
Something to consider with a S-H type V?May not be visible at time of injury (retrospective diagnosis)
~May lead to abnormal growth deformity
Physeal Type VI fractureInjury to the perichondral tissue; injury to bone adjacent to the physis
Possible result of a Type IV fracture?Osseuous bridging of the margin of the physis
Physeal Type VII FRActure?Isolated injry to the epiphyseal plate (physis not involved!)
May be avulsion fracture
Pathological fractures: Features of surrounding bone (5)Cortical thinning/destruction
Medullary bone cystic/destruction
Pperiostal new bond
Unusual shape/pattern/direction of fracture line
Abnormal shape (expansile)
Sesamoid disease: possible etiologies (3)(Rottweiler predisposed)
Bipartite sesamoids (congential)
Nonunion fracture (trauma)
Modeling 2ry to osteoarthritis
Where is sesamoid bone dz usually found?Sesamoids 2 & 7 of digits 2 & 5
When referring to displacement of fragments, how do you describe?Distracted (tension on fragments), impacted, overriding
Always distal relative to proximal fragment
If joint is involved in fracture, how is prognosis affected?Worse (DJD 2ry to fracture)
Why is degree of soft tissue disruption relevant to fracture assessment?Need vascular supply for healing
How do you determine to age of a fracture?Margin
Fracture gap
Callus formation
Periosteal reaction
What does the margin of fracture fragment tell you about fracture age?Sharply delineated = acute fracture
Indistinct, rounded = chronic
What does the density of fragments tell you about fracture age?Persistent normal density = acute
Loss of density = chronic
What does the fracture gap tell you about fracture age?Initially wider, gradually bridged by callus
What does the callus formation tell you about fracture age?Absence = acute, presence = longer-standing
Radiological signs of fracture healing in orderBlurring fracture ends --> Widening fracture gap --> Peri-/Endosteal callus forms --> Bridge fracture gap --> Remodel callus --> Bone shape restored
Primary fracture healing =No callus
Bridging fracture gap by osseus tissue
Secondary fracture healing =Woven bone replaces fracture hematoma & soft tissue callus replaced by lamellar
When should follow-up radiographs be done?2-3 weeks in young, 4-6 weeks in adult
Factors that influence fracture healing (6)Patient (breed, size, age, systemic disease)
Nature of injury (type of bone involved, type of fracture, blood supply, contamination)
Stability (amount of callus formation, fixation method)
Treatment (level & quality of fracture reduction)
Post-op care (Patient & owner compliance)
Complications (Contamination, 2ry infection, delayed/mal-/nonunion)
What does the level of reduction of fragments have to be for good healing?At least 50% of contact between bone ends needed for healing
Secondary fracture healing needs to form ___ to stabilizeCallus
Example of natural splintFractured ulna healing while radius is intact
Possible complication of using stress protection to stabilizeLoss of bone underneate plate --> weakening of bone --> refracture if implant removed
Non-anatomic reduction
Types of non-anatomic reaction (4)Malunion
Hypertrophic non-union
Atrophic non-union
Delayed union
(Thing she mentioned in class as possible complication of pelvic malunion)(Dystocia)
Hypertrophic non-union looks like?Dense, plump ’Elephant foot’
No osseus bridging of fracture gap and closed medullary cavity
Oligotrophic non-union looks like?Absent/only a little callus
Defect non-union looks like?Piece of bone missing (often after comminuted fractures), no cancellous bone graft
Atrophic non-union looks like?Pointed fracture ends, no callus, no bridging fracture gap
Delayed union looks like?Persistent fracture with evidence of healing, open medullary cavity, uneven fracture edges, no sclerosis of fracture ends