About diagnostic imaging of postoperative complication of anterior cruciate ligament (ACL) reconstruction.
This is the case of a patient the came to my observation for a palpable mass into the anterior-medial pretibial region, two years after ACL reconstruction.
Tunnel cyst formation is a rare complication after ACL reconstruction, usually occurring 1-5 years post-operatively, which may occasionally be symptomatic. The ultrasound exam in this case is not enough. The study is completed with MRI and Cone-Beam CT examination.
Why Cone-Beam CT? Same diagnostic capability of total-body CT but low radiation dose!
The computed tomography dose index (CTDI) is a commonly used radiation exposure index in X-ray computed tomography (CT); in this case 4,74 mGy was the value detected. 16.98 mGy is the estimated absorbed dose by using a total-body CT scan for the same examination.
The location of the femoral and tibial tunnels and graft position play a central role in the avoidance of impingement; the femoral tunnel should lie posterior to the intersection of Blumenstaat’s line (BL) with a line parallel to the posterior femoral cortex. This measure is well seen with conventional radiography but Mri imaging also allow to appreciate the integrity of the graft. I use all of the imaging modality in my daily practice but now my preference goes to dedicated systems; I think it’s very important to see what happens during knee flexion-extension to the reconstructed ACL.
