VCA 341 Fall 2011 Andrea Matthews, DVM, Dip ACVR Assistant Professor of Radiology

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 http://www.boingboing.net/images/_i_pix_2007_11_03_CatXrayES2311_800x521.jpg

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

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; 19:168-179

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; 19:168-179

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 • 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 http://www.gentlegiantsrescue.com/images/sheltie%202%20800.jpg

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 http://www.vetmed.wsu.edu/courses_vm551_crd/images/dle.JPG

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!