Dynamic Computed Tomography for assessment of Knee Rotational Stability after Anterior Cruciate Ligament Injury

Rationale: Anterior cruciate ligament (ACL) injury is one of the most common serious knee injuries in the young athlete. The ACL provides stability of the knee in anterior-posterior direction as well as in rotation. There has been a lot of development in ACL reconstruction surgery techniques the past decade. The reconstruction of the ACL complies two main goals, namely: restoration of anterior to posterior stability and restoration of rotational stability. Restoration of anterior to posterior stability can be achieved by reconstruction surgery of the ACL, though it is not well known what influence the ACL reconstruction has on rotational stability of the knee. One of the reasons the ACL reconstruction fails is assumed to be persistent rotational instability of the knee after ACL reconstruction. Though, we cannot measure the rotational stability of the knee reliable for there is currently no reliable technique available. New generation CT scanners (dynamic-CT) make it possible to assess moving joints in a quantitative manner, as is already been shown in the wrist carpal joints.
This technique might provide essential information of knee rotational stability before and in a later stage after ACL reconstruction and hereby, possibly prediction of patient satisfaction after ACL repair.
Objective: To assess the rotational stability of the knee using dynamic CT scanning.
Study design: A feasibility study / pilot study. It will be a cross-sectional design. There will be an internal control. A dynamic CT scan will be performed of the injured as well as the uninjured knee to assess the differences in rotations.
Study population: Patients planned for ACL reconstruction surgery, with a unilateral symptomatic ACL deficiency will be included, 18-50 years of age.
Intervention (if applicable): All participants will receive the same ‘ intervention’, one dynamic-CT scans of each knee, left and right, prior to ACL reconstruction.
Main study parameters/endpoints: Degrees of rotation (femur versus tibia) of the injured versus the uninjured knee.

It is possible to measure knee rotational stability of ACL deficient compared to ACL intact knees using dynamic-CT.

One measurement after ACL rupture

Dynamic CT of the knee