Delayed intra-articular migration of the IntraFix outer sheath after anterior cruciate ligament reconstruction: a case report.

We describe a case of foreign body synovitis caused by delayed intra-articular migration of the outer sheath 5 months after anterior cruciate ligament (ACL) reconstruction with a quadrupled tibialis allograft tendon using the IntraFix device for tibial fixation. The postoperative course was unremarkable. At 5 months after surgery, the patient experienced a sudden catching sensation and a slight pain without any obvious twisting or trauma. At 6 months after surgery, extension deficit was 20°. At arthroscopy, intra-articular migration of the outer sheath from the tibial tunnel and reactive synovitis were observed. The outer sheath in the joint and the inner screw in the tibial tunnel were removed successfully. The ACL graft was well incorporated under good tension. Patient was able to return to her previous level of all daily activities with no further episodes of swelling. To our knowledge, described here is the only case of foreign body synovitis due to intra-articular migration of the unbroken sheath.