Page 44 - Demo

Chapter 242DiscussionThe studies regarding ACL deficient subjects differed too much in study protocols to compare results in a proper manner. Therefore, no general conclusion can be drawn on the amount of range of tibial rotation in ACL deficient subjects. The included studies in this review report ACL reconstruction resulting in an average reduction of 17-32% of tibial rotation when comparing preand postoperative state. This finding seems to be consistent over different flexion angles. A study comparing it with a pre-injury state is yet to be designed, so whether it returns to pre-injury levels remains unclear. Studies using Pivot shift test without an objective, external measurement technique for rotational measurement were excluded. Previous work by Musahl showed a wide variation in pivot shift technique as well as clinical grading between examiners.24 Therefore the use of pivot shift as a sole measurement technique was regarded as a too subjective. Several techniques for measuring tibial rotation have been used: MRI, biplanar fluoroscopy, CAS, motion capture systems and several newly developed devices. For the purpose of this review studies using motion capture systems have been excluded. The endless possibilities in (cutting) manoeuvres make comparison between studies very hard. Newly developed devices to measure tibial rotation were excluded when no reference method (e.g. CAS) was used as a comparison. A remarkable outlier in table 1 is the study performed by Hemmerich. Hemmerich used MRI scans before and after ACLR to compare the range of tibial rotation. Reported values are out of range when comparing them to the results of the other studies reported in table 1. Most likely this is the result of a different measuring technique. As Hemmerich is the only study using the MRI technique, the authors cannot validate their outcome. Each measuring method has his own limitations. 21 When using CAS, sensors are placed on the tibia and femur which can be detected by infrared cameras. Measuring intra-operative rotation during computer assisted surgery has shown a high reliability and is easily applied and very reproducible. Skin Mark Zee.indd 42 03-01-2024 08:56