Is the age of the patient useful in the differential diagnosis?
Patient age is extremely useful in differential diagnosis. With the exception of infection (which occurs in all age groups), some joint diseases presenting as monoarticular arthritis are more likely to occur at certain ages.
• In children, consider congenital dysplasia of the hip, slipped capital femoral epiphysis, transient synovitis of the hip, Legg–Calvé–Perthes disease, or a monoarticular presentation of juvenile idiopathic arthritis.
• In young adults, consider seronegative spondyloarthropathy, rheumatoid arthritis, or internal derangement of the joint. A septic joint in this age group is often due to gonococcal infection.
• Older adults are more likely to have crystalline arthritis, osteoarthritis, osteonecrosis, or internal derangement of the joint. A septic joint in these individuals is less likely due to gonococcal organisms.