Does a lateral plasty control coupled translation during antero-posterior stress in single-bundle ACL reconstruction? An in vivo study

The objective of this study was to quantify, in vivo, the reduction of knee laxity obtained by an extra-articular procedure, added to hamstring single-bundle (SB) anterior cruciate ligament (ACL) reconstruction in controlling coupled tibial translation during the Lachman and drawer tests. Twenty-eight patients were evaluated with a computer-assisted kinematic evaluation protocol; patients with associated ligament tears or meniscal damages were not included in the study. All patients underwent an hamstring ACL with an additional extra-articular procedure. During the intervention, tibia was tracked during the Lachman and drawer tests with ACL-deficient knee, after SB fixation and after extra-articular plasty fixation, performed with the remnant part of the hamstring tendons, from end of lateral condyle to Gerdy's tubercle. Statistical analysis was performed to see whether there was a difference in knee laxity after the tests in the three steps. At 30°, the SB graft reduces AP translation of about 5 mm (P <0.05) while the extra-articular procedure controls lateral tibial compartment, reducing translation by 1.6 mm (P <0.05). At 90° the SB graft reduces AP translation more in the lateral compartment (P <0.05), while the extra-articular procedure contributes in controlling tibial translation reducing laxity by 1 mm (P <0.05) in both compartments. Result shows that, in vivo, the addition of an extra-articular procedure to single-bundle ACL reconstruction may be effective in controlling coupled tibial translation during the Lachman test and reduces AP laxity at 90° of flexion.