Plain Film Diagnosis of Arthritides (The Basic Edition) Jacob Walter, M4

Four main categories of arthritis Degenerative  Osteoarthritis (OA)  Secondary – Systemic: hemochromatosis, hemophilia Inflammatory  Seropositive – rheumatoid arthritis (RA)  Seronegative – reactive arthritis, ankylosing spondylitis, psoriatic arthritis, and enteropathic arthritis (assoc with IBD) Infectious Crystal deposition  Calcium pyrophosphate deposition disease (CPPD)  Monosodium urate crystals - Gout This is not a complete list, but will hopefully get you started

When evaluating arthritis, take into account… Location – bilateral/unilateral, which joint(s) Which part of the joint is involved, even or uneven Demographics – age, gender Presence of osteophytes, erosions, new bone formation, subchondral cysts, sclerosis… Soft tissue swelling Or, ABCDE’s: Alignment, Bone proliferation, Cartilage (joint space loss), Density (bone), Erosions, soft tissues

Degenerative Osteoarthritis (OA) Secondary – Systemic: hemochromatosis, hemophilia

Degenerative - Osteoarthritis Characteristics  Uneven loss of joint space  Osteophyte formation  Normal bone mineralization  Relative absence of erosions  Subchondral cysts and new bone formation/sclerosis  Asymmetric distribution, usually hands, feet, knees and hips  Not as common in shoulders, elbows  Associated with changes d/t age, and mechanical forces

OA cont. Hand/Wrist  DIP and PIP involvement, sparing of MCP  Osteophyte formation with soft tissue swelling (Heberdon node at DIP, Bouchard at PIP)  Usually 1 st metacarpal/trapezium/navic ular involvement in wrist Feet  Most commonly 1 st MTP joint

OA cont. Knee  Medial joint involvement more common  Varus deformity of joint, lateral tibial subluxation Hip  Most often superiolateral joint involvement with loss of cartilage and osteophyte formation  Medial sclerosis/new bone formation in femoral neck cortex; buttressing STATdx Cyst Buttressing Osteophyte

Erosive OA OA with an inflammatory component Same OA distribution, but may see erosions or ankylosis Often postmenopausal women

Degenerative – Systemic Hemochromatosis Abnormal iron deposition throughout the body, including articular cartilage Demonstrates some overlap with CPPD, Fe inhibits pyrophosphatase and can lead to crystal deposition in cartilage (chondrocalcinosis) Uniform joint space loss Bilateral symmetrical distribution “Beak-like” osteophytes Subchondral cysts/sclerosis Osteoporosis

Hemochromatosis cont Most often in wrist and hand, esp. 2 nd and 3 rd MCP joints Flattened metacarpal heads Systemic disease may appear similar to CPPD, but with more indolent course and predominance of osteophytes

Degenerative - Systemic Hemophilia  Repetitive hemarthrosis and intraosseous bleeding are causative  Overgrown/ballooned epiphyses  Subchondral cysts  Tissue swelling, evidence of hemarthrosis  Osteoporosis  Late uniform space loss  Sporadic, asymmetric distribution  Late osteoarthritis changes  Knee > elbow > ankle >hip (joints most likely to receive trauma)

Hemophilia cont Pseudotumors  Bleeding in to soft tissues, subperiosteal, or intraosseous areas  May cause some bone destruction or periosteal bone formation  Do not confuse with malignancy

Inflammatory RA Seronegative  Reactive  Ankylosing Spondylitis  Psoriatic  Enteropathic

Inflammatory – Seropositive Rheumatoid Arthritis Periarticular soft tissue swelling Osteoporosis Uniform joint space loss Marginal erosions  severe subchondral erosions No bone formation (no osteophytes) Subluxations Synovial cysts Bilateral and symmetric Generally not present in axial skeleton, except C-spine Hands > feet > knees > hips > C-spine > shoulders > elbows Erosions, uniform joint spaces

RA cont In hand and wrist, often involves carpals, MCP joints and PIP joints  Ulnar subluxation of proximal phalanges and formation of swan neck and boutonniere deformities  Formation of subcutaneous rheumatoid nodules In the foot, erosion of distal metatarsals, and eventual radial subluxation of proximal phalanges  Tarsal joint spaces may also be heavily involved

RA cont Knees affected symmetrically and bilaterally  Uniform space loss  Outpouching of synovial cysts into adjacent bone, or soft tissue (Baker’s cyst) Hips affected in 50%  Uniform cartilage loss  axial or superomedial migration of femoral head  Bone erodes on joint side, and forms on pelvic side leading to acetabuli protusio (acetabulum protrudes into pelvis) STATdx Erosions and joint space loss bilaterally, no osteophytes or sclerosis Baker’s cyst Effusion

RA cont Shoulder and elbow also show bilateral, uniform joint space loss with osteoporosis and cysts formation Special consideration: RA patients are prone to developing laxity of transverse ligament between atlas and odontoid process  Normal distance between the two on lateral c-spine is 3mm in adults, 5mm in children  Increased distance may indicate need for surgical fusion to prevent cord compression during flexion

Inflammatory Arthritis – Seronegative Associated with HLA-B27 Negative RH factor Axial skeleton often involved  Sacroiliitis or spondylitis Enthesopathy  Inflammation of the insertions of tendons/ligaments

Inflammatory – Seronegative Reactive Arthritis (Reiter’s) Reiter’s included the classic triad of arthritis, conjunctivitis, and urethritis Classical model involving chlamydial infection doesn’t apply to all cases, and Reiter was a WWII war criminal, so reactive arthritis is now the preferred term Reactive arthritis may still involve chlamydial infection, but may also occur after gastroenteritis (Shigella, Salmonella, Campylobacter, Yersinia, C. defficile) Likely autoimmune reaction, joints themselves are not infected Worldwide has equal prevalence among men and women

Reactive cont Enthesopathy is prominent, with overlying tissue warmth and tenderness Soft tissue swelling (sausage digits) Uniform joint space loss Bilateral, asymmetrical Often begins with one joint, don’t confuse with septic arthritis Areas of erosion associated with periosteal reaction, new bone formation Most often in feet, ankles, knees and SI joints Less in hands, hips, spine

Reactive cont Very often involves Achilles tendon insertion, preference for MTP and 1 st IP joint in feet (vs DIP and PIP in psoriatic) In SI joint, may be on only one side or asymmetrically affect both sides (opposed to ankylosing spondylitis) May form large, asymmetric bony bridges between vertebrae (similar to psoriatic, but opposed to ankylosing spondylitis) I got tired of bone pics, so here’s some chlamydia!

Inflammatory – Seronegative Ankylosing Spondylitis Bilateral, symmetrical Ankylosis, joint fusion, is prominent Before fusion, subchondral bone formation Post fusion, generalized osteoporosis No cysts or subluxation Erosions not a prominent feature, but are present SI and spine (ascending) involvement > hips > shoulders > knees > hands > feet

AS cont Fusion of SI joints is classic Vertebral bodies initially erode at corner, reactive sclerosis occurs below this leading to squared appearance  Eventually anulus fibrosus and longitudinal ligaments become ossified (syndesmophytes)  Discs can become calcified, along with all ligaments including those between spinous processes  bamboo spine Dagger sign, fused spinous process ligaments

Inflammatory – Seronegative Psoriatic Arthritis Bilateral, asymmetrical Dramatic joint space loss +/- ankylosis (arthritis mutilans) Bone proliferation, “mouse ears” “pencil-in-cup” deformities Normal mineralization Sausage digits Hands > feet > SI > spine Usually favors DIP and PIP in hand SI involvement usually bilateral, asymmetrical Large bridging bone formation in spine, similar to reactive arthritis Sausage digits info/psoriatic-arthritis/diagnosis.html

Inflammatory – Seronegative Enteropathic Arthritis 20% of patients with inflammatory bowel disease develop arthritis Axial disease is very similar to AS with spine and SI joint involvement  Radiographically almost identical to AS  Progresses independently of IBD activity Peripheral arthritis/arthralgia waxes and wanes with IBD activity  Oligoarthritis of lower extremities  Erythema nodosum and pyoderma gangrenosa may be concurrent Whipple’s disease, pancreatic disease, cirrhosis, and infection such as Salmonella and Shigella may also be associated with arthritis

Infectious Septic arthritis

Septic arthrtitis Joint space destruction, both sides, due to release of proteolytic enzymes Joint effusion Soft tissue swelling Osteoporosis In healthy patients  Knee, hip, and elbow common  N. gonorrhoeae most common cause in young, sexually active patients IV drug users  SI joint, sternal, pubic joints TB  Hip, knee, intertarsal joints, spine  TB in vertebral disc space is Pott’s disease Staph aureus is most common cause, Streptococcus is also common Gram negatives more common in diabetics Salmonella in sickle cell patients Risk factors: Extremes of age, immunocompromised, chronic arthridities, prosthetic joints, diabetes, and IV drug use

Septic arthritis cont Uhh, do you see the problem? Pott’s

Sedona, AZ (crystals) Gout CPPD

Crystals Gout Monosodium urate crystal deposition  May deposite in cartilage to produce an OA like disease, or in soft tissues (tophaceous gout) Usually males, postmenopausal females Tophaceous gout  Tophi  Relative joint space preservation  Erosive lesions with sclerotic borders, away from joint space, with overhanging cortex  Normal mineralization  Asymmetrical, polyarticular  May present with acute, monoarticular swelling, pain, and erythema.  Feet (1 st MTP) > ankles > knees > hands > elbows

Gout cont Uwmsk.org/residentprojects/gout.html Erosion with overhanging edge. Joint space is preserved. tophus Crystal in PMN from synovial fluid, diagnostic for acute gout

Crystals CPPD Most common crystal arthropathy Disease spectrum includes:  Deposition in cartilage (chondrocalcinosis), which may lead to OA like disease or be asymptomatic Commonly develops in older population Associated with hyperparathyroidism and hemochromatosis  Pseudogout which may present with acute attacks of arthritic pain similar to gout, although it is more common in the knees than the 1 st MTP May be indistinguishable from septic arthritis without synovial fluid analysis

Chondrocalcinosis Most common in knee, pubic symphysis, and wrist (patients will be affected in at least one of these areas) Deposition of crystals in hyaline and/or fibrous cartilage Bilateral Cysts Normal mineralization Subchondral new bone formation +/- osteophytes Knees > hands > hips Shoulder and elbow involved, differentiates from OA wikipedia Uwmsk.org/residentprojects/ gout.html

Sources Bowen, Anne C. Arthritis in Black and White. Philadelphia: Saunders, 1988 Current Rheumatology Diagnosis & Treatment, Second Edition John B. Imboden, David B. Hellmann, John H. Stone. Gay, Spencer B. Woodcock, Richard J Jr. Radiology Recall. Baltimore: Lippincott, 2000 Pretorius, E. Scott. Solomon, Jeffery A. Radiology Secrets. Philadelphia: Mosby 2006 Marc Gosselin, M.D., OHSU