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Several anatomical anterior cruciate ligament (ACL) reconstruction techniques have been proposed to restore normal joint kinematics. However, the relative superiorities of these techniques with one another and traditional single-bundle reconstructions are unclear. Kinematic responses of five previously reported reconstruction techniques (single-bundle reconstruction using a bone-patellar tendon-bone graft [SBR-BPTB], single-bundle reconstruction using a hamstring tendon graft [SBR-HST], single-tunnel double-bundle reconstruction using a hamstring tendon graft [STDBR-HST], anatomical single-tunnel reconstruction using a hamstring tendon graft [ASTR-HST], and a double-tunnel double-bundle reconstruction using a hamstring tendon graft [DBR-HST]) were systematically analyzed. The knee kinematics were determined under anterior tibial load (134 N) and simulated quadriceps load (400 N) at 0°, 15°, 30°, 60°, and 90° of flexion using a robotic testing system. Anterior joint stability under anterior tibial load was qualified as normal for ASTR-HST and DBR-HST and nearly normal for SBR-BPTB, SBR-HST, and STDBR-HST as per the International Knee Documentation Committee knee examination form categorization. The analysis of this study also demonstrated that SBR-BPTB, STDBR-HST, ASTR-HST, and DBR-HST restored the anterior joint stability to normal condition while the SBR-HST resulted in a nearly normal anterior joint stability under the action of simulated quadriceps load. The medial-lateral translations were restored to normal level by all the reconstructions. The internal tibial rotations under the simulated muscle load were over-constrained by all the reconstruction techniques, and more so by the DBRHST. All five ACL reconstruction techniques could provide either normal or nearly normal anterior joint stability; however, the techniques over-constrained internal tibial rotation under the simulated quadriceps load. [ABSTRACT FROM AUTHOR]

Background: Recently, anatomic anterior cruciate ligament (ACL) reconstruction is emphasized to improve joint laxity and to potentially avert initiation of cartilage degeneration. There is a paucity of information on the efficacy of ACL reconstructions by currently practiced tunnel creation techniques in restoring normal joint laxity.Study Design: Controlled laboratory study.Hypothesis: Anterior cruciate ligament reconstruction by the anteromedial (AM) portal technique, outside-in (OI) technique, and modified transtibial (TT) technique can equally restore the normal knee joint laxity and ACL forces.Methods: Eight fresh-frozen human cadaveric knee specimens were tested using a robotic testing system under an anterior tibial load (134 N) at 0°, 30°, 60°, and 90° of flexion and combined torques (10-N·m valgus and 5-N·m internal tibial torques) at 0° and 30° of flexion. Knee joint kinematics, ACL, and ACL graft forces were measured in each knee specimen under 5 different conditions (ACL-intact knee, ACL-deficient knee, ACL-reconstructed knee by AM portal technique, ACL-reconstructed knee by OI technique, and ACL-reconstructed knee by TT technique).Results: Under anterior tibial load, no significant difference was observed between the 3 reconstructions in terms of restoring anterior tibial translation (P > .05). However, none of the 3 ACL reconstruction techniques could completely restore the normal anterior tibial translations (P < .05). Under combined tibial torques, both AM portal and OI techniques closely restored the normal knee anterior tibial translation (P > .05) at 0° of flexion but could not do so at 30° of flexion (P < .05). The ACL reconstruction by the TT technique was unable to restore normal anterior tibial translations at both 0° and 30° of flexion under combined tibial torques (P < .05). Forces experienced by the ACL grafts in the 3 reconstruction techniques were lower than those experienced by normal ACL under both the loading conditions.Conclusion: Anterior cruciate ligament reconstructions by AM portal, OI, and modified TT techniques are biomechanically comparable with each other in restoring normal knee joint laxity and in situ ACL forces.Clinical Relevance: Anterior cruciate ligament reconstructions by AM portal, OI, and modified TT techniques result in similar knee joint laxities. Technical perils and pearls should be carefully considered before choosing a tunnel creating technique. [ABSTRACT FROM AUTHOR]

Purpose: The function of the medial collateral ligament (MCL) during gait has not been investigated. Our objective was to measure the kinematics of the medial collateral ligament during the stance phase of gait on a treadmill using a combined dual fluoroscopic imaging system (DFIS) and MRI technique. Methods: Three-dimensional models of the knee were constructed using magnetic resonance images of 7 healthy human knees. The contours of insertion areas of the superficial MCL (sMCL) and deep MCL (dMCL) on the femur and tibia were constructed using the coronal plane MR images of each knee. Both the sMCL and the dMCL were separated into 3 portions: the anterior, mid, and posterior bundles. The relative elongation of the bundles was calculated using the bundle length at heel strike (or 0% of the stance phase) as a reference. Results: The lengths of the anterior bundles were positively correlated with the knee flexion angle. The mid-bundles of the sMCL and dMCL were found to function similarly in trend with the anterior bundles during the stance phase of the gait and their lengths had weak correlations with the knee flexion angles. The elongations of the posterior bundles of sMCL and dMCL were peaked at mid-stance and terminal extension/pre-swing stance phase. The lengths of the posterior bundles were negatively correlated with the knee flexion during the stance phase. Conclusion: The data of this study demonstrated that the anterior and posterior bundles of the sMCL and dMCL have a reciprocal function during the stance phase of gait. This data provide insight into the function of the MCL and a normal reference for the study of physiology and pathology of the MCL. The data may be useful in designing reconstruction techniques to better reproduce the native biomechanical behavior of the MCL. Level of evidence: IV. [ABSTRACT FROM AUTHOR]

Background: Anatomical reconstruction techniques that can restore normal joint kinematics without increasing surgical complications could potentially improve clinical outcomes and help manage anterior cruciate ligament injuries more efficiently. Hypothesis: Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft can more closely restore normal knee anterior-posterior, medial-lateral, and internal-external kinematics than can conventional single-bundle anterior cruciate ligament reconstruction. Study Design: Controlled laboratory study. Methods: Kinematic responses after single-bundle anterior cruciate ligament reconstruction and single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft were compared with the intact knee in 9 fresh-frozen human cadaveric knee specimens using a robotic testing system. Kinematics of each knee were determined under an anterior tibial load (134 N), a simulated quadriceps load (400 N), and combined torques (10 N·m valgus and 5 N·m internal tibial torques) at 0°, 15°, 30°, 60°, and 90° of flexion. Results: Anterior tibial translations were more closely restored to the intact knee level after single-tunnel double-bundle reconstruction with anatomical placement of hamstring tendon graft than with a single-bundle reconstruction under the 3 external loading conditions. Under simulated quadriceps load, the mean internal tibial rotations after both reconstructions were lower than that of the anterior cruciate ligament-intact knee with no significant differences between these 3 knee conditions at 0° and 30° of flexion (P > .05).The increased medial tibial shifts of the anterior cruciate ligament-deficient knees were restored to the intact level by both reconstruction techniques under the 3 external loading conditions. Conclusion: Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft can better restore the anterior knee stability compared with a conventional single-bundle reconstruction. Both reconstruction techniques are efficient in restoring the normal medial-lateral stability but overcorrect the internal tibial rotations. Clinical Relevance: Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft could provide improved clinical outcomes over a conventional single-bundle reconstruction. [ABSTRACT FROM AUTHOR]

Background: Anatomic double-bundle reconstruction has been thought to better simulate the anterior cruciate ligament anatomy. It is, however, a technically challenging procedure, associated with longer operation time and higher cost. Hypothesis: Double-bundle anterior cruciate ligament reconstruction using a single femoral and tibial tunnel can closely reproduce intact knee kinematics. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen human cadaveric knee specimens were tested using a robotic testing system to investigate the kinematic response of the knee joint under an anterior tibial load (130 N), simulated quadriceps load (400 N), and combined torques (5 N·m valgus and 5 N·m internal tibial torques) at 0°, 15°, 30°, 60°, and 90° of flexion. Each knee was tested sequentially under 4 conditions: (1) anterior cruciate ligament intact, (2) anterior cruciate ligament deficient, (3) single-bundle anterior cruciate ligament reconstruction using quadrupled hamstring tendon, and (4) single-tunnel-double-bundle anterior cruciate ligament reconstruction using the same tunnels and quadrupled hamstring tendon graft as in the single-bundle anterior cruciate ligament reconstruction. Results: Single-tunnel-double-bundle anterior cruciate ligament reconstruction more closely restored the intact knee kinematics than single-bundle anterior cruciate ligament reconstruction at low flexion angles (≤30°) under the anterior tibial load and simulated muscle load (P < .05). However, single-tunnel-double-bundle anterior cruciate ligament reconstruction overconstrained the knee joint at high flexion angles (?60°) under the anterior tibial load and at 0° and 30° of flexion under combined torques. Conclusion: This double-bundle anterior cruciate ligament reconstruction using a single tunnel can better restore anterior tibial translations to the intact level compared with single-bundle anterior cruciate ligament reconstruction at low flexion angles, but it overconstrained the knee joint at high flexion angles. Clinical Relevance: This technique could be an alternative for both single-bundle and double-tunnel-double-bundle anterior cruciate ligament reconstructions to reproduce intact knee kinematics and native anterior cruciate ligament anatomy. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were to determine: (1) the kinematic effect of subtotal medial meniscectomy on the anterior cruciate ligament (ACL)–deficient knee and (2) the effect of ACL reconstruction on kinematics of the knee with combined ACL deficiency and subtotal medial meniscectomy under anterior tibial and simulated quadriceps loads. Methods: Eight human cadaveric knees were sequentially tested using a robotic testing system under 4 conditions: intact, ACL deficiency, ACL deficiency with subtotal medial meniscectomy, and single-bundle ACL reconstruction using a bone–patellar tendon–bone graft. Knee kinematics were measured at 0°, 15°, 30°, 60°, and 90° of flexion under an anterior tibial load of 130 N and a quadriceps muscle load of 400 N. Results: Subtotal medial meniscectomy in the ACL-deficient knee significantly increased anterior and lateral tibial translations under the anterior tibial and quadriceps loads (P < .05). These kinematic changes were larger at high flexion (≥60°) than at low flexion angles. ACL reconstruction in knees with ACL deficiency and subtotal medial meniscectomy significantly reduced the increased anterior tibial translation, but could not restore anterior translation to the intact level with differences ranging from 2.6 mm at 0° to 5.5 mm at 30° of flexion. ACL reconstruction did not significantly affect the medial–lateral translation and internal–external tibial rotation in the presence of subtotal meniscectomy. Conclusions: Subtotal medial meniscectomy in knees with ACL deficiency altered knee kinematics, especially at high flexion angles. ACL reconstruction significantly reduced the increased tibial translation in knees with combined ACL deficiency and subtotal medial meniscectomy, but could not restore the knee kinematics to the intact knee level. Clinical Relevance: This study suggests that meniscus is an important secondary stabilizer against anterior and lateral tibial translations and should be preserved in the setting of ACL reconstruction for restoration of optimal knee kinematics and function. [Copyright &y& Elsevier]