Stress radiography for quantifying posterior cruciate ligament deficiency

PURPOSE: The objective of this study was to evaluate the efficacy of different stress radiography techniques in quantifying a posterior cruciate ligament (PCL) lesion. TYPE OF STUDY: Prospective serial study. METHODS: Sixty patients with subacute or chronic PCL injuries, confirmed using magnetic resonance imaging (MRI) or arthroscopic evaluation, were enrolled in this study. The patients underwent a KT-2000 (Medmetric, San Diego, CA) examination and a series of stress radiographs that included a radiographic posterior drawer test with Telos (Telos, Weterstadt, Germany) at 90 degrees and 25 degrees of knee flexion, an active radiograph at 90 degrees of knee flexion, and an axial view radiograph. RESULTS: Stress radiography performed with Telos showed an average posterior tibial displacement of 11.54 +/- 4.93 mm and 7.97 +/- 3.16 mm at 90 degrees and 25 degrees, respectively. The active radiographs showed an average posterior tibial displacement of 11.48 +/- 5.14 mm. CONCLUSIONS: Stress radiographs were shown to be superior to arthrometric evaluation in quantifying posterior tibial translation. The techniques performed with the knee at 90 degrees of knee flexion allowed for greater posterior tibial displacement and, consequently, an easier quantification of the degree of ligament insufficiency. Stress radiographs performed through hamstring contraction gave the same results as those performed with Telos at 90 degrees of knee flexion.