DEVELOPMENT, VALIDITY & RELIABILITY OF LACHMANN-O-METER TO DETECT ANTERIOR CRUCIATE LIGAMENT LAXITY IN A SAW BONE MODEL: A NEW PORTABLE, AUTOMATED ATHROMETER

We developed an arthrometer to detect ACL laxity that are automated, portable, user friendly and sensitive to detect ACL laxity called Lachman-O-Meter. This study is to assess the efficiency of the newly developed Lachman-O-Meter in detecting ACL laxity in a saw knee bone model in comparable to Lachman test. This was a pre-clinical, study on a saw bone knee models representing different grading of Lachman test; three button, two button and zero button knee model. Examiners were blinded and performed Lachman test on each saw bone model and were asked to grade it as soft end point, firm end point or negative Lachman test. Then, the examiner used Lachman-O-Meter on the saw bone model and record the finding. Criterion validity were performed using correlation analysis between the results of Lachman-O-Meter and the Lachman test. The sensitivity was 100% , specificity of 80% , positive predictive value of 90.9 %, and negative predictive value of 100%, in detecting ACL laxity with firm and soft end point. In zero button model, examiner able to identify the ACL laxity using Lachman-O-Meter, with 90% accuracy in identifying Lachman test with soft end point, (r= 0.80, 95% CI: 0.29–1.22, p = <0.001). In two button model, examiner able to identify the ACL laxity using Lachman-O-Meter, with 100% accuracy in identifying Lachman test with firm end point, (r= 1, CI: 0.29–1.22, p = <0.001). Lachman-O-Meter is an efficient tool to be used in the diagnosis of different degrees of ACL laxity with high sensitivity and specificity, and excellent inter and intra-rater reliability本研究研发了一款名为Lachman-O-Meter的关节测量仪，该仪器具备自动化、便携易用、操作简便且对前交叉韧带（Anterior Cruciate Ligament, ACL）松弛度检测灵敏度高的特点，用于ACL松弛情况的检测。本研究旨在评估新型Lachman-O-Meter检测锯骨膝关节模型中ACL松弛度的效能，并与传统拉赫曼试验（Lachman test）进行对比。本研究为临床前研究，采用代表不同拉赫曼试验分级的锯骨膝关节模型，包括三按钮、双按钮及零按钮膝关节模型。采用盲法设计，由测试者对每一个锯骨膝关节模型进行拉赫曼试验，并将结果划分为软终点、硬终点或阴性拉赫曼试验三类。随后，测试者使用Lachman-O-Meter对该锯骨膝关节模型进行检测并记录结果。通过对比Lachman-O-Meter与拉赫曼试验的检测结果进行相关性分析，以验证其效标效度。在检测具有硬终点与软终点的ACL松弛情况时，该仪器的灵敏度达100%，特异度为80%，阳性预测值为90.9%，阴性预测值为100%。在零按钮模型中，测试者借助Lachman-O-Meter识别ACL松弛情况的准确率达90%，可准确区分软终点类拉赫曼试验结果（相关系数r=0.80，95%置信区间CI：0.29~1.22，p<0.001）。在双按钮模型中，测试者借助Lachman-O-Meter识别ACL松弛情况的准确率达100%，可准确区分硬终点类拉赫曼试验结果（相关系数r=1，95%置信区间CI：0.29~1.22，p<0.001）。综上，Lachman-O-Meter是一款高效的检测工具，可用于不同程度ACL松弛的诊断，具备高灵敏度与特异度，且拥有优异的评分者间与评分者内信度。