The purpose of this study was to measure the strains of normal and lax anterior cruciate ligament (ACL) under serial loading using specially designed ACL strain analyzer (ASA) during arthroscopic examination.

The study is based on sixty-eight patients. Before the arthroscopic examination, all cases were divided into three groups according to their laxity based on Lachman test, KT2000 arthrometer, and magnetic resonance imaging. During arthroscopic examination, the ASA was connected with ACL using anteromedial portal with the knee flexed in 90. Under serial loading to ACL, the strains were illustrated and calculated.

A statistically significant differences had been shown in strains between normal and lax ACL. Using ANOVA test, the ASA results according to preoperatively divided groups showed no significant differences between all groups and each loads.

We had designed newly diagnostic method for estimate of ACL laxity, and measured the strains of lax ACL compared with normal ACL. This diagnostic method will be helpful to establish treatment plan for injuried ACL during arthroscopic examination.