Musculoskeletal examination and the limping child — formative SAQs

SAQ 1 (10)

A five-year-old boy is brought to the emergency department with a one-day history of a limp and refusing to walk properly. He had a viral upper respiratory infection last week. His temperature is 39.2 degrees Celsius, he holds his right hip flexed and abducted and resists any movement, and he will not bear weight on the right leg. [4] [8]

a) State the four Kocher predictors for differentiating septic arthritis from transient synovitis of the hip, and give the predicted probability of septic arthritis when all four are present. (4 marks) [4]

b) Name the additional predictor identified in the Caird prospective study, state its threshold, and explain why it strengthens the bedside prediction. (2 marks) [6]

c) Outline the immediate management of this child, naming the investigation that is both diagnostic and therapeutic and the team that must be involved. (2 marks) [7]

d) The parents ask whether this is just a viral limp that will settle. Explain in plain language why this child cannot be managed conservatively and what the risk of delay is. (2 marks) [4]

SAQ 2 (10)

A four-year-old girl presents with a three-week history of an intermittent limp and pain in her left knee. She is afebrile, walks with an antalgic gait but bears weight, and has a full range of movement at the knee. Her mother notes the limp is worse in the mornings and improves after she has been playing for half an hour. [1] [7]

a) Describe how you would perform the pGALS screen, naming the three screening questions and the four examination components. (4 marks) [1]

b) Given the morning stiffness and the chronic limp, state the diagnosis you must consider beyond transient synovitis, and name the sight-threatening complication that demands a slit-lamp examination. (2 marks) [7]

c) The knee pain has prompted the mother to ask about a knee problem. State the principle that governs examination of the hip in any child with knee pain, and explain why. (2 marks) [8]

d) Outline the age-stratified differential diagnosis of the limping child, naming one diagnosis for each of the toddler, school-age, and adolescent age bands. (2 marks) [7]