2015 ISAKOS Biennial Congress ePoster #1296
Bio-Interference Screw Cyst Formation in Anterior Cruciate Ligament Reconstruction – 16 Year Follow Up
Simon M. Thompson, MBBS, BSc(Hon), MSc, MD(Res), FRCS(Tr&Orth), London UNITED KINGDOM
Sebastian Fung, MD, Sydney, NSW AUSTRALIA
David G. Wood, MBBS, FRACS, FA(Orth)A, Sydney, NSW AUSTRALIA
NSOSMC and Mater Imaging, Sydney, nsw, AUSTRALIA
FDA Status Not Applicable
Summary: This study has shown that poly L-lactide bioabsorbable screws take longer to resorb than initial in vitro data suggested, and it is unclear whether ganglion formation within the tibial tunnel is related to screw resorption or the hamstring graft.
MRI examinations assessed the resorption of a poly L-lactide bioabsorbable interference screw used in anterior cruciate ligament reconstruction with a 4-strand hamstring technique.
A consecutive series of nine patients undergoing ACL reconstruction using a 4-strand hamstring technique were assessed with MRI scans at 1,2,4,7,10,12 and 16 years postoperatively.
No resorption had occurred after 1,2 and 4 years. After 7 years screw resorption was complete in 7 patients and partial in 3. The formation of a cyst occurred in 3 patients between 5 and 7 years, with half the patients demonstrating small fluid collections within the tibial tunnels. At 10 years most screws were fully resorbed, however cyst formation was common, including the development of a new cyst in the period between 7 and 10 years in one patient. One patient was lost to follow up at 16 years. 16 year results minimal changes to 10 year results. None of the patients had instability, persistent effusions, or clinically detectable adverse reactions to the screws.
This study has shown that poly L-lactide bioabsorbable screws take longer to resorb than initial in vitro data suggested. It is unclear whether ganglion formation within the tibial tunnel is related to screw resorption or the hamstring graft. The theoretical advantages of bioabsorbable screws must be weighed against these findings.