Preoperative Instrumented Evaluation of Anterior and Posterior Laxity of the Knee Joint

In order to justify the diagnostic criteria for the cruciate ligament injury of the knee joint, a series of 44 Chinese patients were enrolled for retrospective analysis. There were 15 anterior cruciate ligament (ACL) and 29 posterior cruciate ligament (PCL) injuries. In addition, 80 normal volunteer subjects were recruited for the control group. Preoperatively, all the patients underwent the KT-1000 and Genucom analyses (except for 6 PCL patients without the Genucom test) of the injured and uninjured knees. Similarly, all the control subjects underwent the same assessments. In the ACL deficient group, the between-knee displacement difference in the anterior drawer test at knee flexion of 30° was 5.2 ± 3.9 mm with KT 1000, and 3.5 ± 2.1 mm with Genucom. The between knee difference of quadriceps active displacement and manual maximum displacement in KT-1000 were 4.4 ± 3.3 mm and 4.8 ± 2.3 mm, respectively. In the PCL deficient group, the between-knee displacement difference via posterior drawer test at knee flexion of 70° was 8.2 ± 3.9 mm with KT-1000, while with Genucom at knee flexion of 90°, the displacement difference was 4.6 ± 4.8 mm. Meanwhile, the quadriceps active displacement in KT-1000 was 4.9 ± 2.2 mm at knee flexion of 90°. All of the ACL deficient patients exhibited a more than 2 mm between knee difference in the manual maximum test. Among the PCL deficient knees, 97% of them in the corrected posterior drawer test and 89% in the quadriceps active displacement, exhibited a greater than 3 mm between knee difference. A significant side-to-side difference existed between the injured patient and control normal subjects (p < 0.001). The findings indicated that the between-knee difference of more than 3 mm in the corrected posterior drawer test is highly suggestive of a PCL injury; while a 2 mm in manual maximum displacement implied the existence of ACL insufficiency. These results could be useful in substantiating the clinical screening judgement of cruciate ligamentous injury of knee joints, in addition to the history and physical examinations.