Abstract des Autors

Stability of the knee joint may be limiting performance in sports. Especially the ACL frequently gets injured. Several testing methods are known to diagnose the stability of the knee joint. Most of them have two disadvantages: 1. Data displayed by pointer-and-scale meters are not suited for transient measurement. 2. The devices and methods can only be used, if the patient lies on the back with the knee joint muscles relaxed. We developed a device to measure the tibial translation at the knee joint. With the corresponding method, we are able to measure the drawer under functional conditions. The purpose of the study was to measure the size of the tibial translation and reflex activities of the knee joint muscles in dependence on AC-status, load of the leg and size and dynamic of the applied mechanical stimulus. We compared a group of subjects (N=12) with AC-reconstruction with a control group (N=12). In our investigations we induced an anterior drawer while the patients were standing upright with the knees slightly bend: The force, the knee joint angle and the EMGs of hamstrings and quadriceps were recorded and with the new device the anteroposterior shift of the tibia was measured. The load of the leg (loaded/unloaded), the force applied to evoke the drawer (100N/200N) and the dynamic of the applied force (slow/fast) were varied. The drawer reached a maximum of 6,0 mm under the condition leg unloaded/200N/slow. Under the condition "fast", reflex activities with a latency of about 60-70ms were recorded. We expect to measure the drawer at the knee joint exactly under functional conditions. Muscular contribution to knee joint stability can be estimated by recording reflexes of these muscles with the EMG. Verf.-Referat