Broken femoral cross pin after hamstring anterior cruciate ligament reconstruction: case report

Two years after a quadrupled hamstring anterior cruciate ligament reconstruction using polylactic acid cross pin femoral fixation, a 32-year-old woman presented with symptoms of knee catching, locking, and stiffness. Diagnostic arthroscopy revealed a loose body in the anterior compartment of the knee which was determined to be part of the polylactic acid femoral fixation pin. The graft was intact and well fixed. After simple arthroscopic removal, the patient returned to full activities and resumed normal function postoperatively. We speculate that the fixation pins may have entered the notch and later degraded or fractured. Using axial magnetic resonance images, we provide preliminary data suggesting that pins angled posterior to the epicondylar axis may violate the notch. If pins are to be placed posterior to the epicondylar axis, maximum pin length can be estimated by the formula: 0.4 x the interepicondylar distance.