Diagnostic Accuracy and Reliability of Dynamic Handheld Ultrasound Testing in Detecting Anterior Cruciate Ligament...

Anterior cruciate ligament (ACL) injuries can go undetected in the initial encounter, and delayed diagnosis can cause instability and an elevated risk of osteoarthritis. We hypothesized that dynamic testing under handheld ultrasound assessments of ACL insufficiency offers high diagnostic accuracy and reliability.

Ten fresh-frozen knee specimens were evaluated in three conditions: (1) intact ACL, (2) complete ACL deficiency, and (3) ACL and Anterolateral ligament (ALL) deficiency. Dynamic testing under ultrasound was performed while simulating the Lachman test (tibial anterior translation with 0 and 100N, at 20 degrees knee flexion) and pivot shift test (internal rotation torque with 0 and 10Nm). The probe was placed at the anterior medial (AM) and lateral (AL) joint line, and anterior translation of the tibia (ΔD) relative to the femur was calculated. Intra-observer and inter-observer reliability were calculated, and receiver operating characteristic (ROC) curve analysis was performed for an ideal cutoff point for detecting knee instability.

From the AM view, ACL-deficient and ACL+ALL-deficient conditions significantly increased ΔD of the tibia during anterior loading compared to the intact ACL condition. The median ΔD values of the tibia in AM view with anterior drawer load were 0.64 (-0.10, 2.67) mm (intact ACL), 4.76 (2.46, 7.21) mm (ACL deficiency), and 3.88 (2.08, 7.23) mm (ACL+ALL deficiencies). The area under the ROC curve identifying ACL deficiency was 0.89 (95%CI, 0.66-0.97) in the AM view with anterior loading simulating the Lachman test. The optimal cut-off value to distinguish between the intact and ACL-deficient condition for anterior tibial translation with loading was 2.6 mm (sensitivity=80%, specificity=90%).

Dynamic examination of the knee using portable handheld ultrasound from an AM view has high sensitivity and specificity in diagnosing ACL injury.