Pascal Christel

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction With Anatomic Aimers

Graft positioning is a key issue in anterior cruciate ligament (ACL) reconstruction and even more sensitive in double-bundle reconstruction, where 2 tunnels have to be drilled within the ACL footprints at both the femoral and tibial insertion sites. Specific ancillary instruments have been developed to facilitate the positioning of the 4 sockets necessary when performing anatomic double-bundle ACL reconstruction. This technical note describes the rationale and the step-by-step method of using the specific aimers developed for this purpose. However, a prerequisite for successful double-bundle ACL reconstruction is a good knowledge of ACL footprint anatomy.

Reconstruction du ligament croisé antérieur par greffe de tendons de la patte d'oie à un ou à deux faisceaux : Comparaison biomécanique sur genoux cadavériques

Resume Le ligament croise anterieur (LCA) est compose de deux faisceaux antero-medial (AM) et postero-lateral (PL) au role biomecanique distinct. Les techniques classiques de reconstruction du LCA par greffe a un faisceau ne remplacent que le faisceau AM. L’hypothese de travail est que la reconstruction du LCA par greffe a un faisceau ne restaure pas une stabilite physiologique. La reconstruction des deux faisceaux du LCA doit permettre potentiellement de retablir une laxite plus proche de la normale que la reconstruction a un faisceau. L’etude, controlee et randomisee, a ete realisee sur 16 genoux cadaveriques apparies avec randomisation de la technique de reconstruction. La subluxation anterieure du tibia a ete mesuree avec un arthrometre, le Rolimeter™, en traction manuelle maximum, a 20°, 60° et 90° de flexion, sur le genou intact, apres section du LCA et apres reconstruction arthroscopique du LCA a un faisceau 4 brins ou deux faisceaux deux brins en utilisant les tendons de la patte d’oie. La variation de longueur de chaque faisceau reconstruit a ete mesuree. Dans le groupe 1 faisceau, la variation de longueur de la greffe entre 0° et 90° de flexion etait de 0,5 ± 0,7 mm. Pour le groupe 2 faisceaux, la variation du faisceau AM etait de 0,5 ± 0,9 mm et 3,4 ± 0,5 mm pour le faisceau PL. Pour les 16 genoux etudies avec LCA intact la laxite anterieure a 20°, 60° et 90° a ete mesuree respectivement a 3,2 ± 1,1 mm, 3,5 ± 1,5 mm et, 2,6 ± 1,1 mm. Apres section du LCA la laxite augmentait de maniere significative a tous les angles etudies : 9,4 ± 3,3 mm, 6,1 ± 2,5 mm et, 6,8 ± 2,9 mm pour 20°, 60° et 90° de flexion. Apres reconstruction par greffe a un faisceau la laxite anterieure residuelle a 20°, 60° et 90° a ete mesuree respectivement a 3,7 ± 0,9 mm, 3,1 ± 1,1 mm et, 2,3 ± 1,6 mm. L’analyse statistique des resultats utilisant aussi bien les tests parametriques que non parametriques montrait l’existence d’une difference significative de laxite entre LCA sectionne et LCA reconstruit a 20°, 60° et 90° de flexion. Il existait une difference significative entre LCA intact et LCA reconstruit a 20° de flexion, la laxite residuelle etant plus importante apres reconstruction a 1 faisceau. Par contre a 60° et 90° il n’y avait pas de difference significative de subluxation anterieure du tibia que le LCA soit intact ou reconstruit. Apres reconstruction par greffe a deux faisceaux la laxite etait mesuree a 3,4 ± 1,3 mm, 2,6 ± 1,5 mm et 2,4 ± 1,2 mm respectivement pour 20°, 60° et 90° de flexion. L’analyse statistique montrait une diminution significative de laxite entre LCA sectionne et LCA reconstruit a 20°, 60° et 90° de flexion mais, sans difference significative de subluxation anterieure du tibia entre LCA intact et LCA reconstruit a 20°, 60° et 90° de flexion. La reconstruction du LCA par une greffe a deux faisceaux permet de retablir une laxite anterieure similaire a celle du LCA intact a 20°, 60° et 90° de flexion alors que la reconstruction a un faisceau retablit une laxite physiologique a 60° et 90°. Cette amelioration du controle de la laxite anterieure par la reconstruction a deux faisceaux ne represente qu’une legere amelioration par rapport a la reconstruction a un faisceau et le benefice eventuel de la technique a deux faisceaux doit plutot etre evalue au niveau de la stabilite rotatoire.PURPOSE OF THE STUDY We worked with cadaver specimens to evaluate control of anterior knee laxity after reconstruction of the anterior cruciate ligament (ACL) comparing double two-strand anterolateral and posteromedial reconstruction with the classical four-strand technique. We hypothesized that the double reconstruction would provide better control of anterior laxity in both flexion and extension. MATERIAL AND METHODS Sixteen cadaver knees were randomly assigned to reconstruction technique. Anterior tibial translation was measured with an arthrometer (Rolimeter) at maximal manual tension at 20 degrees, 60 degrees and 90 degrees flexion on the intact knee, after section of the ACL and after arthroscopic reconstruction using either the classical four-strand hamstring technique or a double two-strand anteromedial and posterolateral technique. An EndoButtonCL was used for the femoral fixation and a interference screw with staples for the tibial fixation. Variation in the length of each construct was measured between 0 degrees and 90 degrees flexion. RESULTS In the single reconstruction group, the length of the graft varied by 0.5 +/- 0.7 mm between 0 degrees and 90 degrees flexion. In the double reconstruction group, the length varied by 0.5 +/- 0.9 mm for the anteromedial construct and 3.4 +/- 0.5 mm for the posterolateral construct. When studied with an intact ACL, anterior laxity of the 16 knees was 3.2 +/- 1.1, 3.5 +/- 1.5 and 2.6 +/- 1.1 mm at 20 degrees, 60 degrees, and 90 degrees respectively. After section of the ACL, laxity increased significantly at all angles: 9.4 +/- 3.3, 6.1 +/- 2.5 and 6.8 +/- 2.9 at 20 degrees, 60 degrees, and 90 degrees respectively. After classical four-strand single graft reconstruction, the residual anterior laxity was 3.7 +/- 0.9, 3.1 +/- 1.1, and 2.3 +/- 1.6 mm at 20 degrees, 60 degrees, and 90 degrees flexion. Statistical analysis using parametric or non-parametric tests as appropriate showed a significant difference in laxity at 20 degrees, 60 degrees, and 90 degrees of flexion between knees with a cut ACL and knees with reconstructed ACL. At 20 degrees flexion, residual laxity was greater after single-construct reconstruction. At 60 degrees and 90 degrees there was no significant difference in anterior translation of the tibia in knees with intact or reconstructed ACL. After reconstruction with the dual-construct technique, laxity was 3.4 +/- 1.3, 2.6 +/- 1.5, and 2.4 +/- 1.2 mm at 20 degrees, 60 degrees and 90 degrees flexion respectively. Laxity was significantly greater with a cut ACL than after reconstruction at 20 degrees, 60 degrees, and 90 degrees flexion, but there was no significant difference in anterior translation of the tibia at 20 degrees, 60 degrees, and 90 degrees flexion between knees with an intact and a reconstructed ACL. DISCUSSION These results based on a clinical evaluation measuring anterior translation of the tibia with an arthrometer are in agreement with results in the literature using robots. Compared with the classical technique, reconstruction of the ACL with a dual-construct technique provides a statistically significant improvement in control of anterior tibial translation at 20 degrees of flexion. The advantage of the dual anteromedial and posteriolateral construct technique is thus not found in the control of anterior laxity but rather in control of rotation laxity. CONCLUSION Reconstruction of the ACL with a two-bundle graft technique provides control of anterior laxity at 20 degrees, 60 degrees, and 90 degrees flexion similar to that observed in knees with an intact ACL while the single construct technique re-establishes physiological laxity at 60 degrees and 90 degrees only. This improved control of anterior laxity with the two-bundle reconstruction is a small improvement regarding anterior laxity, the more potential advantage concerning rotational stability.