1. 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

2. Complications of Fracture Healing
Malunion
Delayed union
Nonunion
Viable
Nonviable

3. 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

4. Complications of Fracture Healing
Malunion

5. 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
Given enough time and no deterioration of stabilization or other complication, the fracture should eventually heal

6. Complications of Fracture Healing
Delayed union

7. 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

8. 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

9. Complications of Fracture Healing
Nonunion
Viable
Hypertrophic
Oligotrophic
Nonviable (uncommon)
Dystrophic
Necrotic
Defect
Atrophic

10. Complications of Fracture Healing
Viable (reactive or vascular) nonunion
Hypertrophic
Excessive lysis at fracture site
Excessive, nonbridging callus formation (“elephant” or “horse foot”)
Sclerosis of bone fragments
Can have angular limb deformity
Oligotrophic
Little to no callus - Bridging of fracture fragments with fibrous tissue
Difficult to differentiate from nonviable nonunions

11. Hypertophic Nonunion
Note the widening of the fracture gap

12. Hypertophic Nonunion
Note the excessive, non bridging callus

13. Hypertophic Nonunion
Note the sclerotic fracture ends

14. 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:

15. Complications of Fracture Healing
Nonviable nonunion
Dystrophic
Poor vascular supply to at least one fracture fragment
Little to no callus; lucent fracture gap
Necrotic
Lack of blood supply causes sequestrum formation
Bone fragment retains sharp edges and is sclerotic
Defect
Large fracture gap cannot be bridged by callus
Atrophic
Usually progression from one of the other types of nonunions
Little to no callus, loss of vascularity, rounding of bone margins

16. Defect Nonunion
Note the lack of callus formation, resorption and sclerosis of the fracture margins as well as the widening of the fracture gap

17. 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:

18. Diseases Affecting the Joints

19. 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

20. Osteoarthrosis Roentgen signs
Intracapsular soft tissue swelling due to joint effusion and/or synovial proliferation
Usually first pathologic change

21. 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

22. 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

23. 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…

24. Osteoarthrosis

25. Osteoarthrosis

26. 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

27. Osteoarthrosis
Subchondral osteosclerosis
Subchondral osteolysis

28. 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

29. 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

30. Cranial Cruciate Ligament Rupture
Occurrence
Females > males
Young athletic dogs and middle age, over-weight dogs
Acute, non weight-bearing lameness
Roentgen signs
Tibia may be displaced cranially

31. Cranial Cruciate Ligament Rupture
CCL rupture
Normal

32. Cranial Cruciate Ligament Rupture
Roentgen signs
Intracapsular swelling
Effusion and/or synovial proliferation
A – displacement of infrapatellar fat pad
B – displacement of fascial planes caudal to joint

33. Cranial Cruciate Ligament Rupture
Roentgen signs
Secondary osteoarthrosis
Osteophytes on patella, adjacent to trochlear groove of femur, margins of tibial plateau and fabellae

34. Cranial Cruciate Ligament Rupture
Roentgen signs
May seen an avulsion fracture in the cranial joint space
Avulsion fragment

35. Septic Arthritis Occurrence Roentgen signs
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

36. 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

37. Septic Arthritis Osteolysis of subchondral bone
Columnar periosteal reaction
Intracapsular swelling

38. Septic Arthritis Osteolysis of subchondral bone and ulna
Intracapsular swelling

39. 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

40. 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

41. 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

42. Erosive Polyarthritis

43. 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

44. 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

45. Non-Erosive Polyarthritis

46. 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

47. Neoplasia of the Joints
Synovial cell sarcoma

48. 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…

49. The End!