Musculoskeletal Radiography

1. Musculoskeletal Radiography Dr. LeeAnn Pack Dipl. ACVR

2. Musculoskeletal Radiography • Permit localization and characterization of a lesion • Size, shape, margination, number, position, opacity • Normal radiographic anatomy • Diseases are often bilateral in the appendicular skeleton • Radiographic terms – use appropriately

3. Traditional - ABCD’S • Alignment • Judgment based on appropriate radiographic views • Pertains to the bone as well as joint alignment • May require “stress” views to demonstrate abnormal joint alignment • Bone • Assess size, shape, position, opacity, margin and number • Evaluate the periosteum (soft tissue border with a bright light) • Cortex, endosteum, medullary cavity (+/- cancellous bone), endosteum, cortex and periosteum • Subchondral bone plate, epiphysis, metaphysis, diaphysis, metaphysis, epiphysis, subchondral bone plate and any apophyses • Cartilage • Soft tissue opacity of both articular and physeal locations • Relies on knowledge of anticipated joint space width and physeal configuration • Devices • Implant complications • Soft tissue • Extracapsular and intracapsular soft tissues evaluated with a bright light • Opacity changes (mineralization, emphysema, foreign bodies)

4. Approach to Interpretation • Soft tissues • Intra-capsular or extra-capsular • Bones • Evaluate periosteal margins for new bone • Evaluate all cortices and subchondral bone • Evaluate the medullary cavity for changes in opacity • Joints • Evaluate joint capsule attachments • Evaluate joint spaces and peri-articular margins

5. Gas in Soft Tissues • Area of decreased opacity in the ST’s • Causes: • Open wound • Compound fracture • Gas producing organism • Iatrogenic • Post op • Needle stick

6. Mineralization of Soft Tissues • Increased opacity in the soft tissues • Causes: • Dystrophic mineralization • Metastatic mineralization • Neoplastic mineralization

7. Calcinosis Circumscripta

8. Soft Tissue Abnormalities • Intra-capsular soft tissues • Enlargement of soft tissue within the joint • Stifle, tarsus and carpus easiest to evaluate • Swelling usually conforms to joint margins • Can be caused by: • Effusion • Soft tissue proliferation • tumor

9. Intra-capsular ST Swelling

10. Intra-capsular ST Swelling Normal IC Swelling

11. Does This Dog Have Effusion?

12. Soft Tissue Abnormalities • Extra-capsular soft tissues • Enlargement of the soft tissues outside the joint • Swelling may be diffuse or focal • Great indicator of underlying bony change • Caused by • Edema, hemorrhage, tumor, inflammation

13. Bone Abnormalities • Bones response • Bone production - osteoblast • Periosteal reaction and sclerosis • Takes 12-14 days after insult • Bone loss – osteoclast • Lysis • 30-50% bone loss required to be seen on radiographs

14. Bone Loss • Generalized bone loss • Metabolic or Nutritional disease, disuse • Called  osteopenia • Radiographic findings: • Decreased bone opacity, cortical thinning, coarse trabeculation, bone deformity or pathological fractures may occur • Loss of lamina dura – 2ary HPTism

15. Generalized Bone Loss

16. Bone Loss • Localized bone loss • Trauma, infection, tumor • Easier to detect than generalized

17. Bone Loss • Determining Aggressiveness • Zone of transition • The less distinct the margin  the more aggressive the lesion

18. Bone Loss • If the cortex is destroyed, the process is more aggressive than if the cortex is allowed to remodel Intact Destroyed

19. Focal Bone Loss • Geographic Lysis • Large area of lysis • Usually less aggressive • If destroys the cortex  aggressive

20. Focal Bone Loss • Geographic lysis • Expansile appearance • Expansion of the cortex around an enlarging mass  less aggressive • Note the intact cortex in the picture

21. Bone Cyst

22. Focal Bone Loss • Moth Eaten lysis • Multiple smaller areas of lysis • Areas may become confluent • More aggressive than geographic lysis

23. Focal Bone Loss • Permeative Lysis • Numerous small and pin point areas of lysis whose margins are indistinct and fade gradually into normal bone

24. Permeative Lysis

25. Periosteal Reactions - Activity • Classification is based on sharpness of reaction margins • Active = indistinct margins • Inactive = well defined margins

26. Inactive Periosteal Reactions (well defined margins)

27. Active Periosteal Reactions(indistinct margins)

28. Periosteal Rxns - Duration • The older the lesion is  the more opaque (bone like) it becomes • The area under the periosteum is initially soft then as it matures becomes more bone like

29. Immature vs. Mature Reaction

30. Solid Periosteal Reaction • Bone completely fills in the area under the reaction • Surface can be smooth or irregular

31. Solid Periosteal Reaction • The margins are fuzzy so it is still active

32. Lamellated Periosteal Reaction • Reaction has a layered or onion skin appearance • Indicates a cyclic or intermittent process

33. Periosteal Reactions Lamellated Periosteal Reaction This is a semi-aggressive reaction Note the three layers The distal portion is fuzzy so the reaction is active The reaction is of bone opacity so it is chronic or mature

34. Spiculated Periosteal Reaction • Bone incompletely fills the area under the periosteum • More aggressive type of periosteal reaction

35. Spiculated Periosteal Reaction

36. Amorphous Periosteal Reaction • Bone is formed in a disorganized fashion • Process may destroy spicules of bone as they are being formed • This is a very aggressive process

37. Amorphous Periosteal Reaction

38. Codman’s Triangle • There is a solid periosteal reaction seen at the edge of and aggressive reaction

39. Description • Mono-ostotic vs. polyostotic vs. joint centered • Location/s • Periosteal reaction • Active or inactive • Type (solid smooth, solid irregular, spiculated, amorphous) • Duration • Lysis • Type • Cortex destruction • Zone of transition

40. Aggressive Lesions Poorly demarcated Long zone of transition Poorly marginated osteolysis Cortex interrupted Interrupted irregular periosteal reaction No surrounding sclerosis Rapid rate of change Non-aggressive Lesions Well demarcated Short zone of transition Absent or geographic osteolysis Cortex may be displaced, remodeled and thin, but not broken Solid, smooth periosteal reaction +/- surrounding sclerosis Static or slow rate of change The most aggressive feature of the lesion is how the lesion is characterized

41. Differentials • Based on aggressiveness of lesion • Location/s • Mono/ poly-ostotic / joint centered • Must assess signalment and history, location, additional tests… • Many diseases have similar radiographic appearance – may require biopsy

42. Primary Bone Tumors • Radiographic Signs: • Lesion may be primarily productive, lytic or both • Lytic or productive lesions usually have an aggressive appearance • Away from the elbow and toward the knee

43. Primary Bone Tumors • Radiographic Signs: • Typically mono-ostotic • Typically located in the metaphysis • Lesions typically do not cross joints

44. Primary Bone Tumor

45. Primary Bone Tumor

46. OSA – note the ST enlargement

47. Fungal Osteomyelitis • Radiographic Signs: • Typically lesions are seen in the metaphysis • Appear similar to primary bone tumor • Often extensive destruction when a joint is infected (septic arthritis) • Often is poly-ostotic

48. Fungal Osteomyelitis • Etiological Agents: • Blastomyces dermatitidis • Southern states, mid-west and south-west • Coccidioides immitis • Westernstates • Histoplasma capsulatum • mid-western states • Cryptococcus neoformans & Aspergillosis • Throughout the US

49. Fungal Osteomyelitis

50. Fungal