Independent drilling outperforms conventional transtibial drilling in anterior cruciate ligament reconstruction.

BACKGROUND: Optimal tunnel placement is critical in anterior cruciate ligament reconstructive surgery, yet the method used to drill the tunnels may compromise their placement. HYPOTHESIS: An independent drilling method versus a conventional transtibial drilling method will place tunnels in different locations and produce reconstructions with different kinematics. STUDY DESIGN: Controlled laboratory study. METHODS: Ten pairs of knees had anterior cruciate ligament reconstructions produced by either a conventional transtibial drilling method or an independent drilling method. The location of the tunnels was recorded, and the knees were tested for laxity in the normal state, with the anterior cruciate ligament removed, and with the anterior cruciate ligament reconstructed. A surgical navigation system guided the placement of the independently drilled tunnels and measured joint laxity in response to various combinations of anterior force and rotational torques. RESULTS: The conventional transtibial drilling method used in this study placed tibial tunnels posterior and femoral tunnels superior relative to their footprints and resulted in more vertical grafts. In contrast, the independently drilled tibial and femoral tunnels were more anterior and central in their respective footprints, resulting in more horizontal grafts. The horizontal grafts of the independent drilling method were superior to the vertical grafts of this study's transtibial drilling method in restoring normal anterior and rotational knee laxity. CONCLUSION: An independent drilling method can produce tunnels with superior function compared with tunnels produced by a conventional transtibial drilling method. CLINICAL RELEVANCE: Single-bundle anterior cruciate ligament reconstructions will be improved if grafts are centered in their anatomical insertions by an independent drilling method versus grafts placed by a conventional transtibial drilling method.

Anatomical limitations of transtibial drilling in anterior cruciate ligament reconstruction.

BACKGROUND: Recommended techniques for transtibial drilling in anterior cruciate ligament reconstruction are based on strategies to prevent graft impingement and preserve tibial tunnel length. The limitations of this drilling technique may restrict the ability to centralize tunnels in the anterior cruciate ligament footprints. HYPOTHESIS: A transtibial drilling starting point to centralize the tibial and femoral tunnels in their respective footprints can be identified, but it will result in a short tibial tunnel. STUDY DESIGN: Descriptive laboratory study. METHODS: The femoral and tibial attachments of the anterior cruciate ligament were characterized in 12 fresh-frozen cadaveric knees. Knees were secured in 70 degrees and 90 degrees of flexion. A guide pin was drilled antegrade through the central femoral and proximal anterior cruciate ligament attachment sites through the central tibial anterior cruciate ligament attachment site to exit on the anterior tibia. RESULTS: In 90 degrees of flexion using the central femoral and tibial attachment sites, the exit point of the pin on the anterior tibia was 14.1 mm from the tibial joint line and 20.9 mm anterior to the superficial medial collateral ligament. The length of the pin in the tibia was 30.6 mm. Extending the knee to 70 degrees or directing the pin through the proximal femoral anterior cruciate ligament attachment moved the starting point less than 4 mm from this point. CONCLUSION: The transtibial technique can produce tunnels centered in the anterior cruciate ligament footprints, but a starting point close to the tibial joint line is required. This will result in a relatively short tibial tunnel. CLINICAL RELEVANCE: If tunnels centered in the anterior cruciate ligament attachment sites are desired with the transtibial drilling technique, then a short tibial tunnel is necessary. A short tibial tunnel may compromise graft fixation and graft incorporation, or it may result in a tunnel length-graft length mismatch. An alternative drilling strategy might be employed.

The Krackow stitch: a biomechanical evaluation of changing the number of loops versus the number of sutures.

PURPOSE: The purpose of this study was to biomechanically evaluate several configurations of the Krackow stitch and determine which configuration provided the best fixation with regard to load to failure and elongation. TYPE OF STUDY: Biomechanical study. METHODS: Thirty fresh-frozen porcine Achilles tendons were randomly assigned into 6 groups. For 3 of the groups, 1 suture was used (No. 5 Ethibond; Ethicon, Somerville, NJ) with 2, 4, or 6 Krackow locking loops. For the other 3 groups, 2 sutures (interlocking and at 90 degrees) with 2, 4, or 6 Krackow locking loops were used. Data were evaluated using analysis of variance. RESULTS: There were no statistical differences in peak load to failure and elongation among any of the 1-suture techniques regardless of the number of locking loops (2, 290 N; 4, 302 N; and 6, 298 N; standard deviation, 25.2, 9.0, and 28.6, respectively). Similarly, there were no statistical differences among any of the 2-suture techniques regardless of the number of locking loops (2, 534 N; 4, 492 N; and 6, 505 N; standard deviation, 42.0, 65.4, and 76.3, respectively). There was, however, a significant difference (P < .05) in peak load to failure between the 1-suture and the 2-suture groups. The mechanism of failure was suture rupture in all cases. CONCLUSIONS: Load to failure did increase with the addition of a second interlocking suture placed at 90 degrees to the first. CLINICAL RELEVANCE: Tendon fixation with gap formation or suture rupture is at risk of failure. This study identifies that increasing the number of sutures is more important than increasing the number of locking loops.