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Suspected occult intra-articular knee fracture — MSRA MCQ

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HardKnee InjuriesSuspected occult intra-articular knee fractureMSRA

A 46-year-old man presents to general practice 4 hours after falling from a step ladder and landing heavily on his right foot with his knee extended. He developed immediate knee pain and swelling and remains unable to bear weight. At a minor injuries unit, anteroposterior and lateral knee radiographs were reported as showing no fracture. The report notes a fat-fluid level in the suprapatellar recess consistent with lipohaemarthrosis. On review, the knee is moderately swollen and tender over the lateral tibial plateau. He can perform a straight-leg raise. There is no deformity, true locking, distal neurological deficit or vascular compromise. What is the most appropriate management today?

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Correct answer: D — Maintain non-weight-bearing, apply a splint if needed, and arrange same-day emergency orthopaedic trauma assessment

The decisive finding is traumatic lipohaemarthrosis, not the apparently normal plain radiograph. A fat-fluid level in the suprapatellar recess indicates marrow fat and blood within the joint and is highly specific for an intra-articular fracture; an occult tibial plateau fracture is particularly plausible given axial loading, inability to bear weight and focal plateau tenderness. He should therefore be managed as having a fracture pending definitive assessment: non-weight-bearing, splintage if required, and same-day orthopaedic trauma assessment for further imaging and management. A is appropriate for a stable soft-tissue knee injury without evidence of fracture. B may be relevant later for suspected internal derangement, but MRI arranged routinely from primary care would delay fracture-pathway assessment. C recognises that some fractures are initially occult, but delayed repeat radiography is inappropriate where lipohaemarthrosis already provides strong evidence of intra-articular injury. E may occasionally be considered for a tense symptomatic haemarthrosis after specialist assessment, but aspiration neither excludes nor treats the likely fracture and must not delay referral.

Reference: ED/MIU Adult (>16 yrs): Orthopaedic referral pathway (2025) — https://rightdecisions.scot.nhs.uk/media/t1uki5fm/orthopaedic-referral-pathway.pdf Lipohaemarthrosis in knee trauma: an experience of 907 cases (1994) — https://pubmed.ncbi.nlm.nih.gov/8034349/