Differentials
Osteoarthritis (for de Quervain, flexor carpi radialis tenosynovitis)
SIGNS / SYMPTOMS
Direct tenderness over corresponding joint. No tenderness over the suspected tendon.
INVESTIGATIONS
Plain radiographs of affected hand, wrist, and thumb base: arthritic changes including sclerosis, joint space narrowing, osteophytes, and/or cystic changes.
Occult fracture (e.g., scaphoid)
SIGNS / SYMPTOMS
Direct tenderness over corresponding region of bone - at the scaphoid waist in the anatomic snuffbox, or at the volar margin of the scaphoid for tubercle fractures. No tenderness over the suspected tendon.
INVESTIGATIONS
Plain radiograph of affected hand and wrist: occult fracture lines.
CT scan and/or MRI if plain radiograph is negative: occult fracture lines.
Cellulitis
SIGNS / SYMPTOMS
Open wound may be present; acute development of signs. Macular erythema with indistinct borders, warmth, tenderness, and edema.
Diagnosis is clinical in most cases.
INVESTIGATIONS
ESR: elevated.
CRP: elevated.
Fluid Gram stain/culture: may be positive for causative bacteria.
Septic tenosynovitis
SIGNS / SYMPTOMS
Signs of infection, such as erythema, fusiform swelling, and fluctuance, may be present locally.
INVESTIGATIONS
CBC with differential: elevated WBC.
ESR: elevated.
CRP: elevated.
Fluid cell count: elevated.
Fluid Gram stain/culture: may be positive for causative bacteria.
Septic arthritis
SIGNS / SYMPTOMS
Open wound; acute development of signs of joint infection (e.g., pain with passive motion, effusion).
INVESTIGATIONS
CBC with differential: elevated WBC.
ESR: elevated.
CRP: elevated.
Fluid cell count: elevated.
Fluid Gram stain/culture: may be positive for causative bacteria.
MRI: will show a fluid collection or effusion in the joint with possible corresponding bone changes, if chronic.[42]
Rheumatoid arthritis
SIGNS / SYMPTOMS
Systemic signs and symptoms; other joint involvement; history of bilateral, symmetric pain and swelling of the small joints of the hands and feet that has lasted for more than 6 weeks; morning stiffness; rheumatoid nodules over the extensor surfaces of tendons, or vasculitic skin involvement.
INVESTIGATIONS
ESR: elevated.
CRP: elevated.
Fluid cell count: elevated.
Rheumatoid factor: positive in 70%.
Gout
SIGNS / SYMPTOMS
Swelling, effusion, warmth, erythema, and/or tenderness of the involved joint(s).
INVESTIGATIONS
Plain radiograph: degenerative changes.
Uric acid: elevated.
Joint aspirate: needle-shaped crystals strongly negative for birefringence under polarized light.
Dupuytren contracture
SIGNS / SYMPTOMS
Painless nodules in palm and digits; insidious development over months or years. Mild cases easily confused with locked trigger digit.
INVESTIGATIONS
No specific test; clinically palpable cord in palm.
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