Biomechanical Evaluation of Cross-Pin Versus Interference Screw Tibial Fixation Using a Soft-Tissue Graft During Transtibial Posterior Cruciate Ligament Reconstruction

Abstract

Purpose: This article reports the biomechanical demonstration of a technique for transtibial posterior cruciate ligament (PCL) reconstruction using a soft-tissue graft with cross-pin fixation in the tibia and compares this with the biomechanical properties achieved with other methods. Methods: We used 5 paired cadaveric knees and another 10 tibias. Soft-tissue grafts were randomized. The femoral side of the anterior cruciate ligament was fixed with a Bio-TransFix device (Arthrex, Naples, FL) (group I), and the tibial side of the PCL was fixed with a Bio-TransFix device (group II). In another 10 tibias, tibial fixations were performed by use of a bio-interference screw (group III). Biomechanical testing was carried out on a testing machine, and maximal failure load, stiffness, and displacement were analyzed. The lengths of the slots of the TransFix device (Arthrex) from the near cortex were measured to compare the proper length of the device. Results: Maximal mean failure loads in groups I, II, and III were 549.3 +/- 55.4 N, 570.8 +/- 96.9 N, and 371.3 +/- 106.2 N, respectively, showing a significant difference (P = .0003). Stiffnesses were 47.52 +/- 16.84 N/mm, 59.14 +/- 17.09 N/mm, and 27.60 +/- 16.73 N/mm, respectively, showing a significant difference (P = .01). Mean displacements were 19.99 +/- 5.79 mm, 19.09 +/- 8.51 mm, and 17.58 +/- 7.10 mm, respectively, showing no significant difference (P = .7535). The mean lengths of the slots of the TransFix device of the femurs and tibias were similar at 20.3 +/- 1.25 mm and 20.2 +/- 1.32 mm, respectively, showing no significant difference (P = .8637). Conclusions: The transtibial technique by use of cross-pin tibial fixation with a Bio-TransFix device in PCL reconstruction provides stable fixation that is comparable to that achieved by use of conventional bio-interference screw fixation and femoral fixation in an anterior cruciate ligament reconstruction, an already well-established technique. Clinical Relevance: Biomechanically, tibial cross-pin fixation compares favorably with interference screw fixation and is useful when a graft is short. However, safety issues have not yet been resolved.