Osteoarthritis Flashcards
What are some features of ‘atypical’ OA?
Atypical’ OA is suggested by uncommon characteristics, such as onset at a young age or an unusual joint distribution, in a patient who has usage-related pain and signs of joint damage, without inflammation. Such features should alert the clinician to the possibility of an underlying predisposing condition. Young onset monoarticular OA (<50 years old) is most commonly a result of previous major joint injury (e.g., subchondral fracture, torn meniscus, cruciate ligament tear). However, young onset pauciarticular or polyarticular arthritis that clinically, and even radiologically, appears as OA should lead to consideration of specific conditions that predispose to joint damage. Most of these have their own additional clues on enquiry and physical examination.
OA itself is a risk factor for crystal deposition (of calcium pyrophosphate (CPP) and sodium urate). Therefore, if a patient with apparent OA has an additional superimposed inflammatory component, especially with ‘flares’ of clinically overt inflammation, examination of a synovial fluid aspirate, particularly for CPP and urate, is warranted.
What are causes of ‘atypical’ OA with young onset or atypical distribution?
