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7/28/2019 17 Fracture and Dislocation
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FRACTURE AND DISLOCATION
SKELETAL TRAUMA
one of the most important aspects of orthopaedic radiology
commonest problem presented to the musculoskeletal radiologist
FRACTURE occurs when there is a break in the continuity of bone
either complete or incomplete
When a loading force is applied to bone, it initially deforms elastically, and as the load isremoved, the deformity of the bone is reversed and the bone returns to normal.
As the loading force is increased, however, the elasticity of the bone is overcome, and aplastic fiture' occurs, with the bone remaining deformed after cessation of the load.
Finally, complete failure of the bone will occur, giving rise to a true fracture.
Repetitive loading of a bone at `subfracture' levels may lead to the development ofstress fracture
TERMINOLOGIESOpen fracture
Bone fragments penetrate the skin
A comminuted fracture of the tibia, with medialdisplacement and overriding of the distal fragment. Because ofthe Proximity of the skin surface to the anteromedial aspect ofthe tibia, penetration of the skin is likely, and in fact, air is seenin the soft tissues, indicating that penetration is medialdisplacement, but lateral has occurred. There angulation of thedistal fragment. A segmental fibula fracture is noted.
Radiographic signs of open fracture Obvious prorusion of bone fragments beyond the soft tissue margins
Absence of portions of the bone
Gross soft tissue disruption extending to the bone surface
Subcutaneous gas
Foreign material within the fracture
Closed fracture
fracture remains covered with intact skin
Nature of the fracture lines three major types
o transverseo oblique oro spiralo combination
Comminuted fracture
the injury produces more than one fracture line willoften produce a minor triangular fragment of bone,known as a ` butterfly' fragment
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Segmental fracture
o one in which a segment of bone isisolated by fractures at each end
Segmental fracture of thefemur: by definition acomminuted fracture. In this
case the isolated segment isclearly malaligned
Incomplete fractures
occur most commonly in children, when bone resilience is greater, and are of
three typeso plastic fractures
occur when there is bending of the bone without cortical disruption, oracute angulation
o `torus' or ` buckle' fracture
fracture of the cortex on the compressive side of the bone with anintact cortex on the tension side (Fig. 43.4):
Torus fracture of the radius. The cortex isbuckled on the dorsal surface. Apart fromminor plastic deformity, the volar surfaceis intact.
o greenstick fracture converse of the torus fracture, occurring only on the tension side, with
cortical interception
Fractures should also be evaluated for continuity and proximity of the fracture fragments apposition position of the major fragments with respect to each other
distracted fragments which are not apposed are described as being displacementalong the long axis of the bone, or displaced, away from the long axis
o fracture should be described according to the direction of displacement of thedistal fragment relative to the proximal bone
Alignment
refers to the relationship along the axis of major fragments
described in two wayso most logical description refers to the alignment of the distal fragment with
respect to the proximal
additional advantage of following the same rules' as apply todisplacement
o describe the angulation as the direction of the apex of the angle at thefracture site
Alternative method, commonly used by orthopaedic surgeons
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Varus and valgus angulation are terms that are commonly used,particularly by orthopaedic surgeons
refer to the alignment of the distal fragment with respect to themidline of the body, with
o varus angulation of the distal fragment towards the
midlineo valgus reverse
Impaction
descriptive term for fractures in which the bone fragments are driven into each other
ASSOCIATED SOFT TISSUE ABNORMALITIESJoint effusion or hamarthrosis
fractures around a joint providing the joint capsule remains intact
useful at the elbow, where elevation of the pads, either anterior or posterior, is goodevidence of injury
Elbow effusion: elevation of the anterior fat pad (arrow).Although not pathognomonic for fracture, anterior fat pad elevationindicates significant effusion, and is frequently associated with afracture. Careful Inspection of the unfused radial head shows a minorcortical stepoff of the metaphysis, indicating a fracture
lipohamarthrosis
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fat fluid level within a joint
most commonly seen in the knee with radiograph made with a horizontal beam
firm presumptive evidence of an intra articular fracture
Fat fluid level is seen in the knee joint on this cross table view.This indicates intra-articular bone injury.
Soft-tissue swelling in the retropharyngcal space
being a reliable sign of cervical spine trauma
Compression fractures of the vertebral bodies of T7, T8and T9 with large paraspinal haematoma, which took
many months to absorb, still being visible after thefracture had consolidated.
FRACTURE HEALING
After a fracture has occurred, the process of healing begins.
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Stages of healing after a fracture
Considerable bleeding occursat the fracture. The blood liesbetween the bone ends andunder the periosteum.
In a few days a blood clot
forms. Soon the clot isinvaded by osteoblasts fromthe nearby bone and from theperiosteum.
The osteoblasts lay downnew bone which fills the gapbetween the fragments andbulges out at the sides. Thisis the callus.
Over a period of manymonths the callus is absorbedby the osteoblasts, and theymake more new bone exactlylike the original one.
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early stages of bone formation are not visible radiographically
healthy person, new bone formation is visible within 4-6 wks, with the healing processcomplete in 4-6 mos for a single fracture in a large tubular bone
delay in union may be evident by a delay in the appearance of new bone, and can occurfrom a variety of causes
EVALUATION OF SKELETAL TRAUMA
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well defined lesion of mixed signal intensity occupies the regionof the iliopsoas. The Mixed signal pattern is common inhaematoma, indicating the complexity of the haematoma, andvariations in haemoglobin, deoxyhaemoglobin, methaemoglobinand haemosiderin levels
COMPLICATION OF FRACTURE most uncomplicated fractures heal readily, in
open fractures have an increased potential for infection at the fracture site and carefulscrutiny of the healing process is warranted
tibia has long been singled out as a bone liable to delayed union or non-uniono reasons
obscure, but poor vascular supply and lack of immobilisation
due to the large number of 'high-energy' Injuries seen in the tibia,particularly from pedestrian bumper' injuries, with a large amount ofresulting necrosis of soft tissue and bone at and around the fracturesite
Causes of delayed union
Mechanical poor appositionInadequate stabilization
Pathological age-decreased osteoblastic activityDietary-vitamin deficiency (C and D)Pathological fracture (underlying abnormality:infection)
Non-uniono absence of bony union over a prolonged periodo radiographic appearance is usually of a persistent fracture line, usually with
sclerotic margins, and marked surrounding sclerosiso MRI may have a role to play in the assessment of non-union with its ability to
detect infective causes
Causes of non union1. Idiopathic (particularly tibia)2. Poor stabilization3. Infection4. Pathological fracture5. Massive initial trauma
Non-union of the tibia despite interosseousbone grafting and surgical wiring. There issclerosis around the fracture line, withoutfirm evidence of bone bridging, 1 yearafter the fracture
Maluniono fracture which heals in an unsatisfactory anatomical
position, either with excessive overlap of fragments,giving rise to shortening of the bone, or unsatisfactoryangulation or displacement of the distal fragment
Malunion of the tibial fracture, which has healed well,but shows lateral angulation of the distal fragment.
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SPECIAL TYPES OF TRAUMAStress (fatigue) fractures
result from chronic repetitive forces which by themselves are insufficient to causefracture, but over the course of time lead to the classical changes of a stress fracture
occur in many bones, and usually at characteristic sites, often as the result of athleticactivity
example: `march' fracture of the second and third metatarsal head, the stress fractureof the mid and distal tibia and fibula in long-distance runners and ballet dancers, andfractures of the proximal fibula in paratroopers
earliest diagnosis can be made by nuclear medicine scanning or MRIo show increased activity before radiographic signs appear. When radiographic
signs appear, they may take several forms, depending upon the stage of
healing or the chronicity of the stresso hairlike lucency may be seen traversing the hone. New Bone formation around
the fracture may be the only radiographic sign, or may accompany thecortical fracture
Multiple stress fractures are seen, some with obvious horizontallucencies running perpendicular to the bone cortex. The Patient was a joggerwho refused to give up jogging despite the pain
TypesSpondylolysis pars inter- articularis defects
underlying causeso congenital hypoplasia of the articular processeso degenerative change within the posterior joints
Mild degrees of spondylolisthesiso occur when there is loss of articular cartilage at the posterior intervertebral
joints as in degenerative disease More severe spondylolisthesis
o results from pars interarticularis defectso graded according to severity
Grade I up to 25% displacement of the vertebral body Grade II up to 50%
Grade III up to 75% Grade IV 100% displacement
Avulsion fractures
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occur from avulsion of bone fragments at the site of ligamentous or tendinousattachments throughout the skeleton
osteochondritis which represent avulsion fractures from chronic or repeated traumao Osgood-Schlatter disease
diagnosis is made clinically, although it can he suggestedradiographically when there is clear elevation of fragments of the tibial
tubercle separated from the underlying boneo Sindig-Larsen disease of the tibial tubercle and inferior patella respectively
Common avulsion injuries at the origin of muscle tendon insertions arc seen at theo inferior border of the ischium (hamstrings)o Anterior inferior iliac crest (rectus lemons)o lesser trochanter (iliopsoas)
Sites of avulsion fractures with muscle origin
Site of avulsion fracture Muscle originAnterior superior iliac crest SartoriusAnterior inferior iliac crest Rectus femorisIschial tuberosity HamstringsGreater trochanter GlutealsLesser trochanter IliopsoasPosterior calcaneus Achilles tendonOlecranon process TricepsSuperior patella QuadricepsInferior patella (Sinding-Larsen) Patella ligament
Tibial tuberosity (Osgood-Schlatter) Patella ligament
Pathological fractures
occur through bone that has been weakened by an underlying disease
occur through bone that is weakened by such conditions as osteoporosis orosteomalacia, bone tumours (whether benign or malignant) or even tumour-like lesions
of bone In elderly patients underlying malignancy should be considered, especially if the
fracture occurs in a site other than those usually seen in osteoporosis such as thefemoral neck, or in cases in which the severity of the injury is inappropriate to thefracture created
DISLOCATION
When a joint, instead of a bone, suffers a severe strain
No bones are broken, but one bone is pushed out of its proper place
Dislocated joints are very painful
Usually look deformed because the bones are in wrong positionFrom left to right, dislocation of theelbow,knee, and little finger.
RADIOLOGY FRACTURE AND DISLOCATION Page 10From left to right, dislocation of the elbow,knee, and little finger.
http://www.daviddarling.info/encyclopedia/E/elbow.htmlhttp://www.daviddarling.info/encyclopedia/E/elbow.htmlhttp://www.daviddarling.info/encyclopedia/K/knee.htmlhttp://www.daviddarling.info/encyclopedia/K/knee.htmlhttp://www.daviddarling.info/encyclopedia/F/finger_anatomy.htmlhttp://www.daviddarling.info/encyclopedia/E/elbow.htmlhttp://www.daviddarling.info/encyclopedia/K/knee.htmlhttp://www.daviddarling.info/encyclopedia/K/knee.htmlhttp://www.daviddarling.info/encyclopedia/F/finger_anatomy.htmlhttp://www.daviddarling.info/encyclopedia/K/knee.htmlhttp://www.daviddarling.info/encyclopedia/F/finger_anatomy.htmlhttp://www.daviddarling.info/encyclopedia/E/elbow.htmlhttp://www.daviddarling.info/encyclopedia/K/knee.htmlhttp://www.daviddarling.info/encyclopedia/F/finger_anatomy.htmlhttp://www.daviddarling.info/encyclopedia/E/elbow.html7/28/2019 17 Fracture and Dislocation
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Management
Reduction of dislocationo Process of putting the bones back into their normal positions
Anethetic is given to relax the muscles
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