Bicruciate lesion biomechanics, Part 1—Diagnosis: translations over 15 mm at 90° of knee flexion are indicative of a complete tear

Purpose Understanding the pathomechanics of a bicruciate injury (BI) is critical for its correct diagnosis and treatment. The purpose of this biomechanical study aims to quantify the effects of sequential sectioning of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) bundles on knee laxity. Methods Twelve cadaveric knees (six matched pairs) were used. Knee laxity measurements consisted of neutral tibial position, anterior–posterior translation, internal–external rotation, and varus–valgus angulation in different conditions: intact, ACL cut, incomplete BI (divided into two groups: anterolateral (AL) bundle intact or posteromedial (PM) bundle intact) and complete bicruciate tear. Data were collected using a Microscribe system at 0°, 30°, 60°, and 90° of knee flexion. Results In comparison to the intact knees, incomplete BI and complete BI showed a significant increase of total antero-posterior tibial translation. The largest significant increase was observed at 90° of flexion after a complete bicruciate resection ( p 15 mm, in comparison to the intact condition or the contra-lateral non-injured knee, can be used to identify a complete from an incomplete BI.