A Biomechanical Evaluation of the Tibial Cross-Pin Fixation of the Bone-Patellar-Tendon-Bone Graft Using Biointegrable CB Pins: An Experimental Study in Porcine Specimens

Cross-pin fixation of the bone-patellar tendon-bone (BTPB) graft in anterior crucial ligament (ACL) reconstruction using biointegrable CB pins derived from bovine compact bone is a novel and biological fixation method. With the cross-pin fixation, graft fixation can be performed either using two 3-mm diameter CB pins (CB 3 pins) applied across the bone plugs (transcross technique) or one 5-mm diameter CB pin (CB 5 pin) applied across the patellar tendon directly in front of the bone plugs (frontcross technique). No biomechanical data exist for these two cross-pin procedures. A 10-mm wide BPTB graft and the proximal tibia were harvested from 20 fresh pairs of porcine specimens. Transcross fixation (TCP group) and frontcross fixation (FCP group) were performed for fixation of the tibial bone plug inside the tibial tunnel. On 15 specimens in each group, the ultimate failure load was determined by means of single load failure applied parallel to the long tunnel axis. On 5 specimens in each group, bone plug displacement was determined under 1000 load cycles from 50 N to 360 N. The tibial TCP fixation of the BPTB graft using two CB 3 pins demonstrated a maximum failure strength similar to that reported for tibial bioabsorbable interference screw fixation in porcine specimens. The FCP fixation using one CB 5 pin showed a significantly higher value. The recorded bone plug displacements under cyclic loads were minimal and reversible.