Mechanical evaluation of tibial fixation of the hamstring tendon in anterior cruciate ligament double-bundle reconstruction with and without interference screws

ABSTRACT

OBJECTIVE: The objective of this study was to compare two postero-lateral bundle (PLB) tibial fixation techniques for the reconstruction of the anterior cruciate ligament with double bundle a technique without the use of an interference screw, preserving the native tibial insertion of the tendons of the gracilis and semitendineous muscles, and a technique with the use of an interference screw and without preserving the insertion of the tendons. METHODS: A comparative study was conducted in cadavers with a universal mechanical test machine. In total, 23 cadaver knees were randomized for tibial fixation of the PLB using the two techniques Maintaining the tibial insertion of the tendons during reconstruction, without the use of an interference screw (group A, 11 cases); and fixating the graft with an interference screw, without maintaining the insertion of the tendons (group B, 12 cases). A continuous traction was performed (20 mm/min) in the same direction as the produced tunnel, and force (N), elongation (mm), rigidity (N/mm), and tension (N/mm2) were objectively determined in each group. RESULTS: Group A exhibited a maximum force (MF) of 315.4±124.7 N; maximum tension of 13.57±3.65 N/mm2; maximum elongation of 19.73±4.76 mm; force at the limit of proportionality (FLP) of 240.6±144.0 N; and an elongation at the limit of proportionality of 14.37±6.58 mm. Group B exhibited a MF of 195.7±71.8 N; maximum tension of 8.8±3.81 N/mm2; maximum elongation of 15.3±10.73 mm; FLP of 150.1±68.7 N; and an elongation at the limit of proportionality of 6.86±2.42 mm. When comparing the two groups, significant differences were observed in the variables of maximum force (p=0.016), maximum tension (p=0.019), maximum elongation (p=0.007), and elongation at the limit of proportionality (p=0.003). CONCLUSION: The use of the native insertion of the semitendineous and gracilis tendons, without an additional fixation device, presented mechanical superiority over their fixation with interference screws.