Pretibial Cyst Formation in ACL Reconstruction - A Case Report

Abstract

Anterior cruciate ligament (ACL) reconstruction technique was under tremendous improvement during last 10 years; anatomical versus transtibial technique gradually increased, with soft tissue graft overcoming bone-tendon-bone, and biodegradable exceeding metallic implants. Still, complications related to ACL reconstruction are reported; one of it is pretibial cyst formation. Pretibial cyst formation is reported to develop between 2 and 5 years post-operation. We report a case in which the cyst was developed at 2 years after surgery; a biocomposite screw was used for fixation on tibial site, in an ACL reconstruction done with soft tissue autograft. The MRI examination suggested the diagnostic, which was confirmed by histological examination of the cyst. The screw suffered multiple fragmentation; the remnants were retrieved and analyzed. The knee stability was not affected by the cyst development. After retrieval of the screw and appropriate rehabilitation, the patient recovery was complete. The presented case confirms that even biocomposite screw may be related to these sorts of complications, mainly related to plain biodegradable screws. The case offers a point of start for analysis of the literature. A precise ethology of this kind of complications is still unknown; a lot of theories have been developed, two of them seem to be related to our case. Technical improvement together with long time surveillance of cases in which biocomposite implants were used may improve our knowledge concerning the fate of these implants.