Navigation system measures AP and rotational knee laxity in ACL replacement

We used a non-image-based navigation system to measure anterior and rotational laxity during anterior cruciate ligament replacement. The preoperative and postoperative navigated measurements of anterior laxity were compared with the preoperative and postoperative stress radiographs. There was a significant difference between these 2 measurements, but they were significantly correlated. Navigated anterior laxity measurement can therefore be considered reliable. The intraoperative information about the correction of the anterior laxity may have relevance in controlling the quality of the procedure and improving reproducibility. Information about rotational laxity may be helpful, but its exact significance must be more precisely defined.