Unique simultaneous avulsion fracture of both the proximal and distal insertion sites of the anterior cruciate ligament

Abstract

February is a busy month for the ambulance skiing patrol at the skiing resorts in Norway and on this day, a call regarding an 11-year-old boy on one of the hills reached the team. What no one knew at that moment was that this boy had suffered a unique injury and that his X-rays would reveal something that, prior to this, had never been described in the history of mankind. This patient had suffered a simultaneous avulsion fracture of both the femoral and tibial insertion sites of the anterior cruciate ligament without suffering any other injuries to the knee. The injury was treated conservatively and at 1-year follow-up, the patient was completely recovered.

Anatomical Repair of a Femoral-Sided Avulsion Fracture of the Anterior Cruciate Ligament

“…The main mechanism of this injury is assumed to be an acute flexion of the knee combined with internal rotation and anterior displacement of the tibia relative to the femur 3,7,9 . A pivoting movement with knee valgus and external tibial rotation has also been reported to lead to this injury 19 . Both high and low energy can cause the injury as shown in Table I.…”

“…In most femoral-sided avulsion fracture cases, physical examination reveals pain and swelling of the knee, but the Lachman test is not always positive and the pivot-shift test could not be performed as a result of pain and stiffness; therefore, imaging tests are crucial for a definitive diagnosis 7,19 . An avulsion fracture may not be recognized by normal anteroposterior and lateral x-ray, but a notch or tunnel view is reported to be useful for detection [2][3][4]6,9 .…”

“…An avulsion fracture may not be recognized by normal anteroposterior and lateral x-ray, but a notch or tunnel view is reported to be useful for detection [2][3][4]6,9 . CT is the optimal tool to distinguish fragment orientation and engage in preoperative planning; however, MRI is more effective to evaluate the ligament and rule out any possibilities of concurrent femoral involvement 10,11,19 . In our case, the avulsion fracture was easily diagnosed by normal x-ray because of a displaced fragment, but CT and MRI were also needed to obtain detailed information about the fracture and ligament.…”