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Haemarthrosis Differential — SCE Rheumatology MCQ

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EasyRheumatology EmergenciesHaemarthrosis DifferentialSCE Rheumatology

A 50-year-old man develops rapid, tense swelling of his knee after a twisting injury during a football match. Flexion is restricted. Aspiration yields uniformly bloody synovial fluid that does not become clearer in sequential collection tubes. Which group comprises recognised causes of acute traumatic knee haemarthrosis?

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Correct answer: D — Anterior cruciate ligament rupture, patellar dislocation and meniscal tear

Explanation lettering: E = shown as A · A = shown as B · D = shown as C · C = shown as D · B = shown as E

The correct answer is C. A rapid tense effusion after a twisting injury, with uniformly bloody aspirate that does not clear in sequential tubes, indicates a true traumatic haemarthrosis rather than blood introduced by the aspiration. Important causes include anterior cruciate ligament rupture, patellar dislocation and a vascular peripheral meniscal tear; osteochondral injury or intra-articular fracture should also be considered clinically. Gout, calcium pyrophosphate crystal arthritis and septic arthritis usually produce an inflammatory rather than frankly haemorrhagic effusion, although synovial-fluid microscopy and culture may still be required when infection or crystals are suspected. The conditions in D and E are extra-articular and therefore do not cause blood within the joint. Osteoarthritis and inflammatory arthritis are not typical explanations for an acute post-traumatic haemarthrosis.

Reference: Sarimo J, Rantanen J, Heikkilä J, et al. Acute traumatic hemarthrosis of the knee. Is routine arthroscopic examination necessary? A study of 320 consecutive patients. Scandinavian Journal of Surgery. 2002;91(4):361-364. https://pubmed.ncbi.nlm.nih.gov/12558087/