Development of Manual Measurement System with Stereo Markers for Lachman Test

The objective of this paper is to develop a manual measurement system (MMS) for the Lachman test using stereo markers. A novel calculation method that is fit for stereo markers is proposed to analyze knee joint motion in real-time based on the extraction of markers attached on the femur and tibia. In our experiments, knee extension movement and tibial translation are performed with imitation bones to evaluate the accuracy of the system. Further, a simulation of the Lachman test is performed in vivo measurement. The mean error of the knee extension movement in ten cases (range 0° to 90°) was 0.41° with a standard deviation of 0.44°. The mean error of the tibial translation was approximately 0.3 ± 0.9 mm. Experimental results confirmed the acceptable performance of the proposed measurement system, which can be considered for application in clinical manual tests.