Recurrent Tibial Tunnel Cyst Formation Following Anterior Cruciate Ligament Reconstruction and Interference Screw Removal

A unique case of a collegiate athlete who suffered an anterior cruciate ligament injury leading to the formation of a synovial cyst is described. The cyst, localized over the tibial tunnel, resulted from irritation caused by the removal of interference screws. The anterior cruciate ligament (ACL) is one of the four major ligaments of the knee and is regarded as the most critical stabilizer. The ACL stretches from the anterior aspect of the intercondyloid fossa of the tibia just medial and posterior to the anterior tibial spine in a superior, posterior direction to the posterior medial surface of the lateral condyle of the femur. The primary responsibility of the ACL is to prevent anteroposterior displacement of the tibia and restrict rotation of the femur upon the tibia. Although the four ligaments of the knee work as a complex unit to stabilize against various forces, an ACL sprain is considered the most serious ligament injury in the knee (Jenkins, 2002). The ACL is the most frequently ruptured ligament of the knee (Beckett, Massie, Bowers, & Stoll, 1992). The mechanism of ACL injury is often described as non-contact with 71% to 78% of ACL-injured patients describing non-contact mechanisms of injury (Woodford-Rogers, Cyphert, & Denegar, 1994). Given the severity of ACL sprains, reconstructive surgery is often warranted and is performed using autograft (tissue from one’s own body) or allograft (tissue from a cadaver). Use of a tissue graft from the semitendinosous muscle, tensor fascia latae, or, most commonly, the patellar tendon satisfactorily results in increasing stability and function (Buss, Warren, Wickiewicz, Galinat, & Panariello, 1993; Kartus, Magnusson, Stener, Brandsson, Eriksson, & Karlsson, 1999; Tierney, Wright, Smith, & Fischer, 1995). Successful outcome is a function of the graft selection, placement, fixation, and healing as well as repair of secondary restraints. The reconstruction must be able to withstand aggressive, immediate post-operative rehabilitation. As a result, numerous fixation techniques have been developed, yet controversy remains as to which one is ideal (Randall, Wolf, Heilmann, & Lotz, 1999). Most surgeons today use hardware for fixation of the graft outside [EndoButton® (Acufex Microsurgical Inc, Mansfield, MA), suture, post-screw, staple] or inside (nonresorbable and resorbable interference screws, cross pin) the drill holes (Paessler & Mastrokalos, 2003). Ultimately the goal of an ACL reconstruction is to improve the functional capacity of the knee and to prevent further damage to secondary dynamic restraints such as menisci, muscles, and tendons. ACL reconstructions have traditionally required short-stay hospitalizations for adequate pain management and nursing care. However, advances in technology and improvements in technique have reduced operative time for ACL reconstructions and decreased the risk of postoperative complications (Tierney et al., 1995). A commonplace outpatient surgery, ACL reconstruction rarely results in complications (Tierney, et al., 1995). While complications are few, when they occur they include stiffness, quadriceps weakness, bleeding, swelling, and infection (Kartus et al., 1999). Synovial cyst formation over the tibial tunnel is a rare complication after ACL reconstruction (Deie, Sumen, Ochi, Murakami, Fujimoto, & Ikuta, 2000; Feldmann, & Fanelli, 2001; Martinek & Friederich, 1999; Simonian, Wickiewicz, O’Brien, Dines, Schatz, & Warren, 1998; Victoroff, Paulos, Beck,