FUNCTIONAL ULTRASOUND OF THE CRUCIATE LIGAMENTS – A SAFE METHOD TO DETECT KNEE INSTABILITY AND TO CHOOSE THE RIGHT THERAPY

Problemstellung: Trauma to the knee joint often induces ligament insufficiency, either to the anterior or the posterior cruciate ligament (ACL/PCL). Depending on the quality of history taking and physical examination an ACL/PCL insufficiency can be missed which results in chronic instability with secondary cartilage defects and arthrosis. A fixed posterior tibial position following a PCL injury is hard to treat and results after operative repair are often bad. Here we report about our technique of functional ultrasound as a screening method to detect ligament insufficiency in the knee.

Methoden: 30 patients with PCL insufficiency (group 1) and 40 patients with ACL insufficiency (group 2) were examined using the functional ultrasound examination technique described elsewhere [1]. Comparing both knee joints we measured the resting value (RV), ventral translation value (VT) and dorsal translation value (DT). Mean value, standard deviation in mm and t-test for unpaired values were compared with each group and a healthy control population.

Ergebnisse: In group 1 we could distinguish patients with fixed posterior position (PCLmfix) who showed a pathological dorsal RV (2,96mm) from patients without fixation (PCLofix,: RV=0,7mm). DT was significantly prolonged (PCLmfix: 6,4mm; PCLofix: 5,6mm) compared to healthy individuals. Group 2 showed a pathological RV (2,38mm) and a significant prolonged VT (4,19mm). 10 patients in this group had a spontaneous ventral tibia translation (RV: 3,7mm) and 10 patients with ACL insufficiency showed a normal resting value (RV: 0,88mm).

Schlussfolgerungen: Functional ultrasound examination allows us to distinguish between isolated ACL- or PCL-insufficiency and combined injuries of the cruciate ligament complex. The distance (in mm) of translation therefore can help to decide whether or not each individual patient needs operative therapy due to chronic instability. The test also can be used for repeated examination to evaluate the benefit of a primarily conservative treatment with special orthopaedic braces and physiotherapy. A PCL-Insufficiency can be separated in fixed posterior and partly reducible instability which also has impact on the therapy.