Small Animal Orthopedic Radiology Lecture 4 – Fracture Complications Diseases Affecting the Joints VCA 341 Fall 2011 Andrea Matthews, DVM, Dip ACVR Assistant Professor of Radiology
Dec 25, 2015
Small Animal Orthopedic Radiology
Lecture 4 –
Fracture Complications
Diseases Affecting the Joints VCA 341 Fall 2011
Andrea Matthews, DVM, Dip ACVR Assistant Professor of Radiology
Complications of Fracture Healing
Malunion
Delayed union
Nonunion Viable Nonviable
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Complications of Fracture Healing
Malunion Healed but in an abnormal anatomic
position Malunion involving joints will lead to
osteoarthrosis Many malunions in immature dogs are
difficult to recognize after 6-12 months due to extensive remodeling
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Complications of Fracture Healing
Malunion
Complications of Fracture Healing
Delayed union
Fracture is healing but not as quickly as expected
Duration compared to similar fractures and fixation
Subjective assessment – healing is dependant on many factors
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Complications of Fracture Healing
Delayed union
Complications of Fracture Healing
Causes of delayed union
Severe soft tissue damage (poor blood supply) Distracted or over-riding fragments Improper or inadequate reduction or fixation Significant periosteal stripping Removal of large bone fragments Obstruction or destruction of blood supply by implant
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Complications of Fracture Healing
Nonunion
Fracture that has not healed with no evidence of progression to bony union
Different from delayed union in that healing will not proceed without intervention
Often muscle atrophy and lameness Fragment motion may be present pseudoarthrosis Distal radius and ulna of small breed dogs one of most
common sites
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Complications of Fracture Healing
Nonunion
Viable• Hypertrophic
• Oligotrophic Nonviable (uncommon)
• Dystrophic
• Necrotic
• Defect
• Atrophic
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Complications of Fracture Healing
Viable (reactive or vascular) nonunion1. Hypertrophic
• Excessive lysis at fracture site
• Excessive, nonbridging callus formation (“elephant” or “horse foot”)
• Sclerosis of bone fragments
• Can have angular limb deformity
2. Oligotrophic• Little to no callus - Bridging of fracture fragments with
fibrous tissue
• Difficult to differentiate from nonviable nonunions
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Hypertophic Nonunion
Note the widening of the fracture gap
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Hypertophic Nonunion
Note the excessive, non bridging callus
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Hypertophic Nonunion
Note the sclerotic fracture ends
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Oligotrophic Nonunion
Note the rounded fracture ends, sealed medullary
cavity of the distal fragment and minimal
callus formation
Clin Tech Small Anim Pract 2004; 19:168-179
Complications of Fracture Healing
Nonviable nonunion1. Dystrophic
Poor vascular supply to at least one fracture fragment Little to no callus; lucent fracture gap
2. Necrotic Lack of blood supply causes sequestrum formation Bone fragment retains sharp edges and is sclerotic
3. Defect Large fracture gap cannot be bridged by callus
4. Atrophic Usually progression from one of the other types of
nonunions Little to no callus, loss of vascularity, rounding of bone
margins
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Defect Nonunion
Note the lack of callus formation, resorption and sclerosis of the fracture margins as well as the widening of the fracture gap
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Atrophic Nonunion
Note the large fracture gap, no callus, and varying degrees
of sealing of the medullary cavities
Clin Tech Small Anim Pract 2004; 19:168-179
Diseases Affecting the
Joints
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Osteoarthrosis
Also known as Degenerative Joint Disease
A non-inflammatory disorder of synovial joints = osteoarthrosis Osteoarthritis implies inflammation
Slowly progressive degenerative condition
Occurrence Most frequent in the weight bearing joints
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Osteoarthrosis
Roentgen signs Intracapsular soft tissue swelling due to joint
effusion and/or synovial proliferation Usually first pathologic change
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Osteoarthrosis
Roentgen signs Periarticular osteophytes result from articular
cartilage proliferation in the non-weight bearing areas of the joint
Excessive cartilage proliferation outgrows its nutrient supply the cartilage dies it is invaded by vessels and replaced by bone seen radiographically
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Osteoarthrosis
Roentgen signs Joint space alteration
• Decreased size of joint space due to destruction of the articular cartilage
• Alteration in joint space width is best demonstrated on weight bearing views
Artificial narrowing of joint spaces• Obliquity of joints
• Joints that are not in the center of the film
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Osteoarthrosis
Apparent joint space narrowing
Could be real…may be an artifact
See of dogs leg is straight relative to plate to know if real…
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Osteoarthrosis
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Osteoarthrosis
Osteoarthrosis
Roentgen signs Subchondral sclerosis results from trabecular
hypertrophy, compression and collapse of weakened subchondral bone• Also called eburnation
Subchondral osteolysis caused by necrosis of the bone following loss of articular cartilage
Subchondral bone cysts are formed by proliferation of synovium invading the subchondral bone
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Osteoarthrosis
Subchondral osteolysisSubchondral osteosclerosis
Osteoarthrosis
Roentgen signs “Joint mice” or “joint bodies”
are pieces of articular cartilage that detach and are free within the joint. They are visible radiographically when mineralized
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Cranial Cruciate Ligament Rupture
Anatomy and Function Medial aspect of lateral femoral condyle to
intercondylar area of tibia Cranial cruciate ligament (CCL) prevents cranial
displacement of the tibia, limits internal rotation of the tibia and prevents hyperextension of the stifle
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Occurrence Females > males Young athletic dogs and middle age,
over-weight dogs Acute, non weight-bearing lameness
Roentgen signs Tibia may be displaced cranially
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Cranial Cruciate Ligament Rupture
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Cranial Cruciate Ligament Rupture
CCL rupture Normal
Roentgen signs Intracapsular swelling
• Effusion and/or synovial proliferation
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A – displacement of infrapatellar fat pad
B – displacement of fascial planes caudal to joint
Cranial Cruciate Ligament Rupture
Cranial Cruciate Ligament Rupture
Roentgen signs Secondary osteoarthrosis
• Osteophytes on patella, adjacent to trochlear groove of femur, margins of tibial plateau and fabellae
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Roentgen signs May seen an avulsion fracture in the cranial joint
space
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Avulsion fragment
Cranial Cruciate Ligament Rupture
Septic Arthritis
Occurrence Direct inoculation, extension from soft tissue or
bone infections or hematogenous in origin Can also occur in conjunction with other systemic
diseases (Mycoplasma, Leishmania, etc)
Roentgen signs Early infection may show only soft tissue swelling Once bony changes are apparent, the degree of
damage is significant
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Septic Arthritis
Roentgen signs Osteolysis is often seen early in the disease
process, resulting in rough or irregular articular margins
Usually multiple joint surfaces involved Degree of subchondral erosion is much more
severe than with osteoarthrosis In chronic cases, may see periosteal reaction and
osteophytes
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Septic Arthritis
Osteolysis of subchondral bone
Intracapsular swelling
Columnar periosteal reaction
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Septic Arthritis
Osteolysis of subchondral bone
and ulna
Intracapsular swelling
Erosive Polyarthritis
Etiologies Rheumatoid arthritis
• Most common type in dogs
• Small breeds, especially Shetland sheepdog and poodle
Polyarthritis of greyhounds Periosteal proliferative polyarthropathy (cats)
• Older cats
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Erosive Polyarthritis
Roentgen signs Intracapsular soft tissue swelling
only radiographic changes for first few weeks
Cyst-like lucencies in the subchondral bone at the joint capsule attachments and later at the articular margins
Destruction of joint surfaces
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Erosive Polyarthritis
Roentgen signs Narrow joints spaces due to loss
of articular cartilage Subluxation and luxation of the
joints due to destruction of the ligaments
Suspect rheumatoid arthritis radiograph both carpal and tarsal joints as well as any joint that is swollen and painful
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Erosive Polyarthritis
Non-Erosive Polyarthritis
Etiologies Systemic lupus erythematosus (SLE) Idiopathic polyarthritis Feline nonerosive polyarthritis Arthritis associated with chronic infection Polyarthritis/polymyositis syndrome Polyarthritis/meningitis syndrome Plasmacytic-lymphocytic synovitis
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Non-Erosive Polyarthritis
Roentgen signs Intracapsular swelling (joint effusion and/or
increased synovial mass) No osteolysis is noted Multiple joints involved Common sites include carpus, tarsus and stifle
joints
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Non-Erosive Polyarthritis
Neoplasia of the Joints
Occurrence Middle aged to older medium to large breed dogs Rare in the cat From undifferentiated mesenchymal cells of synovium Stifle and elbow are most commonly affected joints
Roentgen signs Early
• Intracapsular and/or extracapsular swelling Later
• Can affect both sides of the joint due to secondary bone involvement
Metastasis to regional lymph nodes and lungs
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Neoplasia of the Joints
Synovial cell sarcoma
Neoplasia of the Joints
Most common joint neoplasia Histiocytic sarcoma Synovial myxoma Synovial cell sarcoma Other neoplastic conditions that can affect the
joints• Rhabdomyosarcoma• Fibrosarcoma• Chondrosarcoma• Malignant fibrous histiocytoma• Liposarcoma• Undifferentiated sarcoma…
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The End!