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A Positive Quadriceps Active Test, without the Quadriceps Being Active
D C Kieser1, E Savage1, P Sharplin1
1Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand.
Case:
A 55-year-old male with a chronic isolated grade 3 PCL injury who demonstrates a positive quadriceps active test without activating his quadriceps musculature.
Conclusion:
Gravity and hamstring contraction posteriorly translate the tibia into a subluxed position. Subsequent gastrocnemius contraction with the knee flexed causes an anterior tibial translation by virtue of the mass enlargement of the gastrocnemius muscular bulk, the string of a bow effect, and the anterior origin of the gastrocnemius in relation to the posterior border of the subluxed tibia aided by the normal posterior tibial slope.
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