1. Imaging approach to joint diseases
Werner Harmse
July 2010

2. Arthritis Indicates an abnormality of the joint as the result of a
degenerative,
inflammatory,
infectious, or
metabolic process.
Affects articular surfaces on both sides of joint
Results in joint space narrowing

3. Classification of arthritides
Degenerative
Osteoarthritis: Primary, Secondary
Inflammatory
Rheumatoid arthritis
Seronegative spondyloarthropathies: AS, Reiter’s, Psoriasis, Enteropathic arthropathies
Connective tissue disease: Scleroderma, SLE, Dermatomyositis
Erosive OA
Metabolic
Crystal deposition: Gout, CPPD, etc
Other deposition: Hemochromatosis, Wilson’s, Alkaptonuria, Amyloidosis
Endocrine: Acromegaly, Hyper-parathyroidism
Haemophilia
Infective
Pyogenic TB
others

5. Imaging of joint disease
X-ray
Ultrasound
MRI CT
Arthrography
Nuclear medicine

6. Ultrasound Multiplanar real time soft tissue imaging
Helpful in diagnosing joint effusions especially in septic arthritis, as well as other fluid collections
Also used in evaluating for tendonitis and tendon rupture

7. CT
Computed tomography (CT) is effective in evaluating degenerative and inflammatory changes of various joints
Findings are similar to plain film radiography, only being able to demonstrate it more clearly
Multiplanar reformations can be done with MDCT
Valuable in planning of surgery
In the assessment of spinal stenosis secondary to degenerative changes, CT examination may also be performed after myelography especially if MRI is contraindicated

8. MRI Excellent contrast between soft tissues and bone.
Articular cartilage, fibrocartilage, cortex, and spongy bone can be distinguished
excellent for demonstrating synovial abnormalities in rheumatoid arthritis.
Because synovitis is often accompanied by joint effusion, this too can be effectively demonstrated by MRI
Occasionally, MRI may provide some additional information in osteoarthritis and hemophilic arthropathy
Most important role is in evaluation of the spine.
Demonstrate hypertrophy of the ligamentum flavum or the vertebral facets
Grade foraminal and spinal stenosis
Evaluate degenerative and inflammatory disc disease
Also very valuable in evaluating joint related injuries

9. Nuclear medicine
Used to evaluate the pattern of disease activity and monitor response
how many joints are affected,
which joints are the most affected,
are there unsuspected sites with disease involvement)
Investigate sites of possible infection
A negative bone scan is reassuring and confirms the absence of active arthritis, while a positive bone scan can demonstrate disease presence and activity before it becomes apparent on a radiograph.
Bone scans have been used to predict erosions in rheumatoid disease and has also been shown to be a good predictor of disease progression in osteoarthritis

10. X-rays: what to look for
Alignment
Bone
Cartilage
Distribution
Soft tissues

11. X-rays: what to look for
Alignment
Subluxation and/or dislocation
Common in RA and SLE
Bone
Osteoporosis
Periarticular osteoporosis in RA
Erosions
Aggressive with no sclerotis margin: RA, psoriasis
Non-aggressive (fine sclerotic border): gout, usually overhanging
Location: Marginal – inflammatory; Central – Erosive OA (gull wing)
Bone production
Osteophytes: at sites of cartilage loss and degeneration typical in OA
Subchondral sclerosis: typical of OA
Ankylosis: seronegative inflammatory arthropathies eg AS
Periosteal reaction: psoriasis, Reiter’s (distinguish from RA)
Subchondral cysts
OA and CPPD, also RA and AVN

12. X-rays: what to look for
Cartilage
Joint space
Normal joint space: Gout; or any early arthropathy
Eccentric narrowing: OA
Uniform narrowing: All others
Wide joint space: early inflammatory process
Calcification: CPPD

13. X-rays: what to look for
Distribution
Single joint: Infective; crystal deposition; post traumatic
Hands and feet
proximal: RA, CPPD, SLE
Distal: Reiter’s(feet), psoriasis(hands), scleroderma
Symmetrical: RA, SLE
SI joints
Asymmetrical: Reiter’s, Psoriasis
Symmetrical: AS, Enteropathic, Reiter’s, Psoriasis
Also DJD, infection, gout

14. X-rays: what to look for
Soft tissues
Swelling
Symmetrical around joint: all inflammatory, but most common in RA
Assymmetrical: most commonly d.t. osteophytes rather than true swelling in OA
Lumpy, bumpy: gout (tophus)
Entire digit: Psoriasis, Reiter’s
Calcification
Soft tissue: Gout
Cartilage: CPPD
Subcutaneous: Scleroderma, dermatomyositis

15. X-rays
First important decision to make is if arthritis is present or not
Almost all arthritides lead to joint space narrowing, except gout
Then decide if it falls in the broader degenerative or inflammatory group as most a fall in one of these two.

16. Arthritis or not
AVN
DJD

17. Inflammatory vs Degenerative
Joint inflammation is characterized by
bone erosions (marginal)
osteopenia
soft-tissue swelling
uniform joint space loss
Degenerative cause of joint space narrowing is characterized by
osteophytes
bone sclerosis
subchondral cysts or geodes
asymmetric joint space narrowing
lack of inflammatory features such as bone erosions

19. Inflammatory

20. Inflammatory Evaluate the number of joints involved
If only a single joint is involved consider infective arthritis
Features of any inflammatory arthritis
But erosions often not acutely present
Joint space may be initially widened due to effusion
Seen easily with ultrasound
Widening also seen in more indolent infections i.e. TB and fungal
Phemister triad in TB arthritis
periarticular osteoporosis,
peripherally located osseous erosions,
gradual diminution of the joint space

23. Progression of TB of the knee over 1 year

24. Inflammatory
If multiple joints are involved consider a systemic arthritis
Now evaluate hands and feet
If proximal with no bony proliferation consider rheumatoid arthritis
If distal with features of bony proliferation consider seronegative spodyloarthropathies eg. AS, Reiter’s, psoriasis and enteropathic arthropathies

25. Rheumatoid arthritis Women aged 30 – 60 Rheumatoid factor
General features of inflammatory arthritis
Additionally joint subluxation and subchondral cysts may also be present
In the hands, target sites include the MCP, PIP, midcarpal, radiocarpal, and distal radioulnar joints, with predilection for the ulnar styloid process
Involvement is usually bilateral and fairly symmetric

26. Rheumatoid arthritis Ulnar deviation occurs at the MCP joints.
Swan neck and Boutonniere deformities.
In the feet, target sites include the MTP, PIP (incl 1st IP) and intertarsal joints
Important to closely evaluate the lateral aspect of the fifth metatarsal head – often 1st site of bony erosion
Also affects tendon sheaths and bursae like the retrocalcaneal bursa:
Loss of the normal radiolucent triangle between the posterosuperior margin of the calcaneus and the adjacent Achilles tendon suggests the presence of bursal fluid, with subjacent calcaneal erosions indicating inflammation

27. Rheumatoid arthritis
Other peripheral joints also affected include the knees, the hips, the sacroiliac and glenohumeral joints.
Spinal involvement affects the C1-C2 articulation
the odontoid process may be eroded
and the anterior atlantodens interval may be abnormally widened (3 mm in adults), especially with neck flexion

29. Small erosions at the 5th MTP joint

30. a) Normal shoulder X-rays in patient with rheumatoid arthritis
a) Normal shoulder X-rays in patient with rheumatoid arthritis. (b) Ultrasound of same patient demonstrates 1.5 cm erosion.

31. Synovial enhancement with Gd-DTPA
Synovial enhancement with Gd-DTPA. (a) Three-dimensional gradient-echo image of a wrist following IV Gd-DTPA shows extensive enhancing synovitis and distention of the synovial cavity. (b) Repeat MRI with Gd-DTPA following 3 months of disease-modifying antirheumatic drug (DMARD) therapy shows marked reduction in the amount of enhancing tissue but similar distention of the synovial cavity (note the dorsally displaced extensor tendons).

32. Seronegative spondyloarhtropathies
Psoriasis, AS, Reiter’s and enteropathic arthritides.
HLA B27 usually positive
Hands and feet show more distal involvement.
Osseous attachment sites of ligaments and tendons are more involved than in RA.
Entheseal involvement leads to increased density and irregular bone proliferation (perisotitis).
Ankylosis more common

33. Psoriatic arthritis Hallmarks
signs of inflammatory arthritis combined with
periostitis, enthesitis, and a distal joint distribution in the extremities
Findings may be bilateral or unilateral and symmetric or assymmetric
Hands more than feet
Involvement of several joints in a single digit, with soft-tissue swelling, produces what appears clinically as a “sausage digit”
Aggressive erosions leading to “Pencil in cup” appearance and resorption of terminal tufts
Fuzzy/fluffy bony proliferation and periostitis
Ivory phalanx
Mouse ears: Bone production adjacent to erosions
SI joint involvement usually bilateral – may be symmetrical or not

34. Psoriatic arthritis. Dorsovolar radiograph of the hand of a 57-year-old woman shows the typical presentation of psoriatic polyarthritis. The “pencil-in-cup” deformity in the interphalangeal joint of the thumb is characteristic of this form of psoriasis.

35. Psoriatic Arthritis. A. Cartilage loss at the PIP joints of the 3rd, 4th, and 5th digits in this hand is apparent, with erosions noted most prominently in the 4th digit (arrow). These erosions are not sharply demarcated but are covered with fluffy new bone. Note also the periostitis along the shafts of each of the proximal phalanges. B. Advanced psoriatic arthritis. Fusion across the PIP joints of the 2nd to 5th digits. Several of the DIP joints are also ankylosed. Severe joint space narrowing at the metacarpophalangeal joints is noted.

36. Reactive arthritis (Reiter’s)
Sterile inflammatory arthritis following an infection at a different site
Young men aged 25-35
Similar to psoriasis in inflammation, proliferation, periostitis and ethesitis
Feet more than hands – particularly MTP joints and heels
Axial skeleton may also be affected

38. A CT scan through the SI joints shows unilateral SI joint sclerosis and erosions (arrows), typical for psoriatic arthritis or Reiter disease.

39. Ankylosing spondylitis
Idiopathic inflammatory arthritis
96% are HLA B27+, Men aged 20 – 40
More commonly affects axial skeleton
Spine involvement is characterized
by osteitis, syndesmophyte formation, facet inflammation, and eventual facet joint and vertebral body fusion.
Sacroiliac joint disease is bilateral and symmetric.
Other peripheral joints, such as the hips and glenohumeral joints, may be involved.

40. Ankylosing spondylitis
SI joints show early erosions best seen at inferior aspects
Sclerosis follows with eventual ankylosis
Spine involvement usually centered at thoracolumbar or lumbrosacral junction
Osteitis at anterior discovertebral junctions with erosions, sclerosis “shiny corner” and squaring of vertebral bodies
Syndesmophytes form with eventual fusion of the vertebral bodies (bamboo spine).
Also interspinous ligament calcification

43. Enteropathic arthritis
Occur with Crohn’s disease, Ulcerative colitis and Whipple disease
Spine and sacroiliac and peripheral joints may be affected.
Spine: squaring of the vertebral bodies and the formation of syndesmophytes are common features.
Sacroiliitis, usually bilateral and symmetric
radiographically indistinguishable from ankylosing spondylitis
In addition, patients may also exhibit a peripheral arthritis, the activity of which generally approximates the activity of the bowel disease.

45. Degenerative
Joint space narrowing, Osteophyte formation, Bone sclerosis and Subchondral cysts are seen in the absence of inflammatory changes
Consider age, joints involved and x-ray appearance to distinguish between
Typical osteoarthritis
Atypical osteoarthritis

46. Typical osteoarthritis
Result of articular cartilage damage and wear and tear from repetitive microtrauma that occurs throughout life, although genetic, hereditary, nutritional, metabolic, pre- existing articular disease, and body habitus factors may contribute in some cases. Usually after 4th or 5th decade
Typical sites
AC joints – small osteophytes from 4th decade
1st CMC joint, IP joints of hands, MCP to a lesser degree, 1st MTP
(joint space narrowing may be symmetrical in hands, unlike larger joints)
Knee – medial joint space as well as patellofemoral. Often formation of osteochondral bodies
Hip – superior migration

49. (A) Sagittal PD of pt with OA of the right knee shows involvement of the femoropatellar compartment. Note joint space narrowing, subchondral cyst (arrow), and osteophytes (open arrows). (B) Coronal T2 fatsat image shows complete destruction of articular cartilage of the lateral joint compartment (arrows), subchondral edema (open arrows), and tear of the lateral meniscus (curved arrow). (C) Sagittal T2-fatsat in another patient shows osteoarthritis of the knee complicated by multiple osteochondral bodies (arrows).

50. Atypical osteoarthritis
Osteoarthritis, but
involved joint is not one commonly affected by osteoarthritis,
the severity of the findings are excessive or unusual, or
the age of the patient is unusual,
then other less common causes for cartilage damage and osteoarthritis should be considered.
Trauma,
Crystal deposition disease,
Neuropathic joint,
Hemophilia.
Other possible causes include congenital and developmental anomalies, such as dysplasia, that disrupt normal biomechanics.

51. Atypical osteoarthritis
Trauma (injury or repetitive stresses)
most common cause,
usually relatively young patient, with marked asymmetric involvement
CPPD
Atypical in joint distribution, excessive subchondral cyst formation and calcium deposition (chondrocalcinosis)
Knee most commonly affected
Radiocarpal and 2nd & 3rd MCP joints
Chondrocalcinosis of triangular fibrocartilage and menisci (also pubic symphysis and hip labrum)

53. Atypical osteoarthritis
Haemochromatosis
Also chondrocalcinosis, with overlap of CPPD findings
More extensive MCP involvement
Metacarpal radial hooklike or drooping osteophytes are more common
Neuropathic joint
Late disease is characteristic with severe joint destruction
sclerosis, fragmentation, subluxation, heterotopic new bone formation
Early disease is similar to OA but distribution is characteristic
Midfoot and hips in DM
Bilateral shoulder joints in a syrinx or spinal tumour
Hips in tertiary syphilis

55. Lisfranc Charcot Joint
Lisfranc Charcot Joint. Dislocation of the second and third metatarsals along with joint destruction and large amounts of heterotopic new bone are present in the foot of this diabetic patient. These findings are classic for a Charcot joint

56. Atypical osteoarthritis
Haemophilia
Repetitive intra-articular haemorrhage may cause cartilage damage
Young patients
Osteophytes, sclerosis and subchondral cyst, but also erosions
Joint space narrowing is more symmetrical
Epiphyseal overgrowth
Knees – squaring of patella and widening of the intercondylar notch
Repeated hemorrhage may produce a large expansile and destructive abnormality known as hemophiliac pseudotumor, most commonly involving the femur and pelvis
overlap between of hemophilia and juvenile chronic arthritis; however, knee, ankle, and elbow involvement are more common in hemophilia.
Remember: Any cause of arthritis can eventually end in secondary or atypical osteoarthritis

57. Advanced haemophilic arthropathy in the elbow

58. Others Juvenile Idiopathic Arthritis (previously known as JRA)
Soft tissue swelling and osteopenia
Delayed joint space narrowing and erosive changes
Possible periostitis and later joint fusion
Osseous overgrowth of the epiphyses due to chronic hyperemia and
Bone undergrowth due to premature growth plate fusion.
Three sub types:
Oligo articular (Prev. pauci articular)
Poly articular
Systemic disease

59. JIA
Oligo-articular
Affects 4 or fewer joints in the first 6 months of illness.
Often ANA positive
50% of JIA cases.
Usually involves the knees, ankles, and elbows but smaller joints such as the fingers and toes may also be affected. The hip is not affected unlike polyarticular JRA.
Usually asymmetrical

60. JIA Poly-articular Systemic JIA
Affecting 5 or more joints in the first 6 months of disease.
More common in small girls to that of boys.
Usually the smaller joints are affected, such as the fingers and hands, although weight-bearing joints such as the knees, hips, and ankles may also be affected. Can include neck and jaw as well.
Usually symmetrical
Systemic JIA
Characterized by arthritis fever and rash
Affects males and females equally.
Systemic JIA may have internal organ involvement and lead to serositis

61. 11-year-old girl with juvenile idiopathic arthritis
11-year-old girl with juvenile idiopathic arthritis. Anteroposterior radiograph of both knees shows bones are osteopenic. Overgrowth of medial femoral condyles and widened intercondylar notch are both recognized features of juvenile idiopathic arthritis.
8-year-old girl with juvenile idiopathic arthritis. Right hand reveals severe changes: marked osteopenia, erosions (arrows), ankylosis of carpal bones and some interphalangeal joints, and subluxation of proximal interphalangeal joints of index and little fingers.

62. Others Erosive osteoarthritis SLE
Distribution similar to OA in hands (IP joints)
Osteophytes
Central gullwing erosions
May end in ankylosis
SLE
Joint space narrowing and erosions are rare
Commonly reducible MCP subluxations

63. Central gullwing erosions in erosive osteoarhtritis
Systemic lupus erythematosus. (A) Typical appearance of the thumb in a 43-year-old woman with systemic lupus erythematosus. Note subluxations in the first carpometacarpal and metacarpophalangeal joints without articular erosions. (B) In anther patient, a 32-year-old woman with SLE, the oblique radiograph of her left hand shows dislocation at the first carpometacarpal joint (arrow) and subluxations in the metacarpophalangeal joints of the index and middle fingers associated with swan-neck deformities (open arrows).
Central gullwing erosions in erosive osteoarhtritis

64. Others Gout Joint space narrowing only occurs late
Characteristic erosions – Punched out, overhanging edges, sclerotic margins, near joint but not specifically marginal
Marked soft tissue swelling due to tophi
Most common in 1st MTP
Also IP joints and tarsal bones
Soft tissue swelling from bursitis as in olecranon bursitis
Radiographic findings may at times be confusing and appear quite unusual, thus it may be helpful to remember, “When in doubt, think gout.”

66. Other diseases involving joints
Synovial osteochondromatosis
caused by a metaplasia of the synovium
results in deposition of foci of cartilage in the joint
mostly deposits calcify and are seen on X-ray
knee, hip, and elbow
Pigmented villonodular synovitis
rare chronic inflammatory process of the synovium that causes synovial proliferation
swollen joint with lobular masses of synovium occurs and causes pain and joint destruction
rarely calcifies
Joints with PVNS look radiographically identical to noncalcified synovial osteochondromatosis
Erosion in 50%: cyst-like defects of varying sizes are present which show sclerotic margins.
PVNS has a characteristic appearance on MR, with low-signal hemosiderin seen lining the synovium on both T1WIs and T2WIs

67. Synovial Osteochondromatosis
Synovial Osteochondromatosis. Anteroposterior view of the hip in this patient with left hip pain shows multiple calcified loose bodies in the hip joint, which is virtually diagnostic of synovial osteochondromatosis.

68. Pigmented Villonodular Synovitis (PVNS)
Pigmented Villonodular Synovitis (PVNS). Sagittal T1W (A) and fast spin-echo T2W (B) images of an ankle with PVNS show a soft tissue mass emanating from the ankle joint, which is low signal on both sequences and has very low signal hemosiderin lining parts of the synovium, which is characteristic for PVNS.

69. spondyloarthropathies
Joint space narrowing
Asymmetric
Osteophytes
Sclerosis
Symmetric
Erosions
Soft tissue swelling
Inflammatory
Degenerative
Unusual
Distribution
Severity
Age
1 joint
> 1 joint
Typical OA
Infection
Atypical OA
Distal
Bony proliferation
No bony proliferation
Proximal
Trauma
Crystal deposition
Neuropathic
Haemophilia
Seronegative
spondyloarthropathies
Rheumatoid
Arthritis
Others: JRA, Gout, SLE, erosive OA,PVNS, Synovial osteochondromatosis

70. References
Jacobson et al. Radiographic evaluation of arthritis: Inflammatory conditions. Radiology 2008; 248:378–389
Jacobson et al. Radiographic evaluation of arthritis: Degenerative Joint Disease and Variations. Radiology 2008; 248:737–747
Weisleder. Primer of Diagnostic Radiology
Brandt & Helms. Fundamentals of Diagnostic Radiology
Greenspan. Orthopaedic Imaging: A ractical approach. 4th Ed