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Abstract Background Quantitative knowledge on the anatomy of the medial collateral ligament (MCL) is important for treatment of MCL injury and for MCL release during total knee arthroplasty (TKA). The objective of this study was to quantitatively determine the morphology of the MCL of human knees. Methods 10 cadaveric human knees were dissected to investigate the MCL anatomy. The specimens were fixed in full extension and this position was maintained during the dissection and morphometric measurements. The outlines of the insertion sites of the superficial MCL (sMCL) and deep MCL (dMCL) were digitized using a 3D digitizing system. Results The insertion areas of the superficial MCL (sMCL) were 348.6 ± 42.8 mm2 and 79.7 ± 17.6 mm2 on the tibia and femur, respectively. The insertion areas of the deep MCL (dMCL) were 63.6 ± 13.4 mm2 and 71.9 ± 14.8 mm2 on the tibia and femur, respectively. The distances from the centroids of the tibial and femoral insertions of the sMCL to the tibial and femoral joint line were 62.4 ± 5.5 mm and 31.1 ± 4.6 mm, respectively. The distances from the centroids of dMCL in the tibial insertion and the femoral insertion to the tibial and femoral joint line were 6.5 ± 1.3 mm and 20.5 ± 4.2 mm, respectively. The distal portion of the dMCL (meniscotibial ligament - MTL) was approximately 1.7 times wider than the proximal portion of the dMCL (meniscofemoral ligament - MFL), whereas the MFL was approximately 3 times longer than the MTL. Conclusions The morphologic data on the MCL may provide useful information for improving treatments of MCL-related pathology and performing MCL release during TKA.

Purpose: This paper investigated the effect of graft fixation sequence on knee joint biomechanics after a double-bundle ACL reconstruction. Method: Two independently published biomechanical studies that investigated the biomechanics of double-bundle ACL reconstructions using similar robotic testing systems were compared. In each study, ten human cadaveric knees were tested under three different conditions: intact, ACL deficient, and ACL reconstructed using a double-bundle technique with the anteromedial (AM) graft fixed at 60° of flexion and the posterolateral (PL) graft fixed at full extension. In one study (Study A), the AM graft was fixed first; while in another study (Study B), the PL graft was fixed first. Knee kinematics, in situ forces of the ACL and the ACL grafts were measured under two loading conditions: an anterior tibial load of 134 N and a combined tibial torques (10 N·m valgus and 5 N·m internal tibial torques) in both studies. Result: When AM graft was fixed first, the in situ force of the AM graft was lower than the native AM bundle at all flexion angles. The in situ force in the PL graft, however, was higher than the native PL bundle at all flexion angles. When the PL graft was fixed first, the in situ force of the AM graft was higher than the native AM bundle, while the in situ forces of the PL graft were lower than the native PL bundle at all flexion angles. Both studies demonstrated that the double-bundle ACL reconstructions can closely restore the normal knee joint kinematics. Conclusion: Even though the grafts were fixed using similar initial tensions and at same flexion angles, the sequence of fixing the two grafts in a double-bundle ACL reconstruction could alter the in situ forces in the grafts and affect the knee kinematics. These data imply that in clinical application of a double-bundle ACL reconstruction, the sequence of graft fixation should be an important surgical parameter. [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: Anterior cruciate ligament (ACL) deficiency alters 6 degrees of freedom knee kinematics, yet only anterior translation and internal rotation have been the primary measures in previous studies. Purpose: To compare the 6 degrees of freedom knee kinematics and the graft forces after single- and double-bundle ACL reconstructions under various external loading conditions. Study Design: Controlled laboratory study. Methods: Ten human cadaveric knees were tested with a robotic testing system under 4 conditions: intact, ACL deficient, singlebundle reconstructed with a quadrupled hamstring tendon graft, and double-bundle reconstructed with 2 looped hamstring tendon grafts. Knee kinematics and forces of the ACL or ACL graft in each knee were measured under 3 loading conditions: an anterior tibial load of 134 N, a simulated quadriceps muscle load of 400 N, and combined tibial torques (10 N·m valgus and 5 N·m internal tibial torques) at 0°, 15°, 30°, 60°, and 90° of knee flexion. Results: The double-bundle reconstruction restored the anterior and medial laxities closer to the intact knee than the single-bundle reconstruction. However, the internal rotation of the tibia under the simulated quadriceps muscle load was significantly decreased when compared with the intact knee after both reconstructions, more so after double-bundle reconstruction (P < .05). The entire graft force of the double-bundle reconstruction was more similar to that of the intact ACL than that of the single-bundle reconstruction. However, the posterolateral bundle graft in the double-bundle reconstructed knee was overloaded as compared with the intact posterolateral bundle. Conclusion: The double-bundle reconstruction can better restore the normal anterior-posterior and medial-lateral laxities than the single- bundle reconstruction can, but an overloading of the posterolateral bundle graft can occur in a double-bundle reconstructed knee. Clinical relevance: Both single-bundle and double-bundle techniques cannot restore the rotational laxities and the ACL force distributions of the intact knee. [ABSTRACT FROM AUTHOR]

Background: The function of the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) during gait has not been reported. Hypothesis: The AM and PL bundles have distinct functional behavior during the stance phase of treadmill gait. Study Design: Descriptive laboratory study. Methods: Three-dimensional models of the knee were created by magnetic resonance images from 8 healthy subjects. The contour of the 2 bundle attachments were constructed on each model. Each bundle was represented by a straight line connecting its tibial and femoral attachment centroids. Next, the knee kinematics during the stance phase of gait was determined with a dual fluoroscopic imaging system. The relative elongation, sagittal plane elevation, coronal plane elevation, and transverse plane deviation of the 2 bundles were measured directly from heel strike to toe-off. Results: At heel strike, the AM and PL bundles had first peak elongation of 9% ± 7% and 9% ± 13%, respectively. At 50% progress of the stance phase, both bundles were maximally elongated, 12% ± 7% for the AM bundle and 13% ± 15% for the PL bundle. No significant difference was found for each bundle between 40% and ±0% of the stance phase (P > .05). With increasing knee flexion, the sagittal plane and coronal plane elevations of the 2 bundles decreased, whereas the deviation angles increased. Conclusion: Both bundles are anisometric and function in a similar manner during the stance phase of gait. They were maximally elongated throughout the midstance where they were stretched maximally to resist anterior tibial translation. Clinical relevance: This information can be useful for further improving anatomical ACL reconstructions to better reproduce the 2 bundle functions. It may also be useful for designing postoperative rehabilitation regimens to prevent overstretch of the grafts. [ABSTRACT FROM AUTHOR]

Background: The in situ forces of the anteromedial (AM) and posterolateral bundles (PL) of the anterior cruciate ligament (ACL) under simulated functional loads such as simulated muscle loads have not been reported. These data are instrumental for improvement of the anatomical double-bundle ACL reconstruction. Hypothesis: The load-sharing patterns of the 2 bundles are complementary under simulated muscle loads. Study Design: Descriptive laboratory study. Methods: Eight cadaveric knees in this study were sequentially studied using a robotic testing system. Each knee was tested under 3 external loading conditions including (1) a 134-N anterior tibial load; (2) combined rotational loads of 10 N·m of valgus and 5 N·m internal tibial torques; and (3) a 400-N quadriceps muscle load with the knee at 0°, 15°, 30°, 60°, and 90° of flexion. The in situ forces of the 2 bundles of ACL were determined using the principle of superposition. Results: Under the anterior tibial load, the PL bundle carried peak loads at full extension and concurrently had significantly lower force than the AM bundle throughout the range of flexion (P<.05). Under the combined rotational loads, the PL bundle contributed to carrying the load between 0° and 30°, although less than the AM bundle. Under simulated muscle loads, both bundles carried loads between 0° and 30°. There was no significant difference between the 2 bundle forces at all flexion angles (P >.05). Conclusion: Under externally applied loads, in general, the AM bundle carried a greater portion of the load at all flexion angles, whereas the PL bundle only shared the load at low flexion angles. The bundles functioned in a complementary rather than a reciprocal manner to each other. Clinical Relevance: The data appear to support the concept that both bundles function in a complementary manner. Thus, how to re-create the 2 bundle functions in an ACL reconstruction should be further investigated. [ABSTRACT FROM AUTHOR]

Background: Quantitative knowledge on the anatomy of the medial collateral ligament (MCL) is important for treatment of MCL injury and for MCL release during total knee arthroplasty (TKA). The objective of this study was to quantitatively determine the morphology of the MCL of human knees. Methods: 10 cadaveric human knees were dissected to investigate the MCL anatomy. The specimens were fixed in full extension and this position was maintained during the dissection and morphometric measurements. The outlines of the insertion sites of the superficial MCL (sMCL) and deep MCL (dMCL) were digitized using a 3D digitizing system. Results: The insertion areas of the superficial MCL (sMCL) were 348.6 ± 42.8 mm² and 79.7 ± 17.6 mm² on the tibia and femur, respectively. The insertion areas of the deep MCL (dMCL) were 63.6 ± 13.4 mm² and 71.9 ± 14.8 mm² on the tibia and femur, respectively. The distances from the centroids of the tibial and femoral insertions of the sMCL to the tibial and femoral joint line were 62.4 ± 5.5 mm and 31.1 ± 4.6 mm, respectively. The distances from the centroids of dMCL in the tibial insertion and the femoral insertion to the tibial and femoral joint line were 6.5 ± 1.3 mm and 20.5 ± 4.2 mm, respectively. The distal portion of the dMCL (meniscotibial ligament - MTL) was approximately 1.7 times wider than the proximal portion of the dMCL (meniscofemoral ligament - MFL), whereas the MFL was approximately 3 times longer than the MTL. Conclusions: The morphologic data on the MCL may provide useful information for improving treatments of MCL-related pathology and performing MCL release during TKA. [ABSTRACT FROM AUTHOR]

Background: Screw and suture fixations are the most commonly used methods of fixation in treatment of anterior cruciate ligament tibial avulsion fractures. Even though a few biomechanical studies have compared the stability of the 2 fixation techniques, a clinical comparison has not yet been reported. Hypothesis: The authors hypothesized that both fixations would be identical in all studied clinical outcome measures at a minimum 2-year follow-up. Study Design: Cohort study; Level of evidence, 3. Materials and Methods: Thirty-three patients treated with either screw fixation (16 patients) or suture fixation (17 patients) within 1 month of the anterior cruciate ligament tibial avulsion fracture (type II or III) without associated ligamentous injury were included. All patients were evaluated at a minimum 2-year follow-up in terms of Lysholm knee scores and return to preinjury activities. Knee stability was compared based on the Lachman test and stress radiography. Results: No significant differences were found between the 2 groups in terms of average Lysholm knee scores (91.7 in the screw group and 92.7 in the suture group, P = .413) at follow-up. All patients except 2 (1 in each group) returned to preinjury activity levels. However, flexion contractures (5° to 10°) were found in 3 patients in the screw group and 2 patients in the suture group without significant intergroup difference. Stabilities based on the Lachman test and instrumented stress radiography were also similar between the 2 groups at follow-up. However, 2 patients in the screw group and 1 in the suture group showed more than 5 mm laxity compared with the contralateral knee on stress radiographs. Conclusion: Both the screw and suture fixation techniques for the anterior cruciate ligament tibial avulsion fracture produced relatively good results in terms of functional outcomes and stability without any significant differences. However, some patients in both groups showed residual laxity or flexion contractures. [ABSTRACT FROM AUTHOR]

Background: The intent of double-bundle anterior cruciate ligament reconstruction is to reproduce the normal anterior cruciate ligament anatomy and improve knee joint rotational stability. However, no consensus has been reached on the advantages of this technique over the single-bundle technique. Hypothesis: We hypothesized that double-bundle anterior cruciate ligament reconstruction could provide better intraoperative stability and clinical outcome than single-bundle reconstruction. Type of study: Cohort study; Level of evidence, 2. Methods: Forty patients with anterior cruciate ligament injury in one knee were recruited; 20 were allocated to a double-bundle anterior cruciate ligament reconstruction group and 20 to a single-bundle anterior cruciate ligament reconstruction group. Intraoperative stabilities at 30° of knee flexion were compared between the 2 groups using a navigation system. Clinical outcomes including Lysholm knee scores, Tegner activity scores, Lachman and pivot-shift test results, and radiographic stabilities were also compared between the 2 groups after a minimum of 2 years of follow-up. Results: Intraoperative anterior and rotational stabilities after anterior cruciate ligament reconstruction in the double-bundle group were significantly better than those in single-bundle group (P = .020 and P < .001, respectively). Nineteen patients (95%) in each group were available at a minimum 2-year follow-up. Clinical outcomes including Lysholm knee and Tegner activity scores were similar in the 2 groups at 2-year follow-up (P > .05). Furthermore, stability results of the Lachman and pivot-shift tests, and radiologic findings at 2-year follow-up failed to reveal any significant intergroup differences (P > .05). Conclusion: Although double-bundle anterior cruciate ligament reconstruction produces better intraoperative stabilities than single-bundle anterior cruciate ligament reconstruction, the 2 modalities were found to be similar in terms of clinical outcomes and postoperative stabilities after a minimum of 2 years of follow-up. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to objectively evaluate whether double-bundle anterior cruciate ligament (ACL) reconstruction can better restore the normal translational and rotational laxities than the conventional single-bundle ACL reconstruction among the reported biomechanical studies., Methods: A systematic literature search was conducted to identify in vitro and in vivo (intraoperative) biomechanical studies that compared the laxities (anterior or anteroposterior or rotational) between single- and double-bundle ACL reconstructions. Because of large variability among the loading conditions and testing methods used to determine the rotational laxities among the studies, a meta-analysis of rotational laxities was not feasible., Results: Seven in vitro and three in vivo studies were included in this analysis based on the predefined inclusion criteria. The overall mean differences calculated by the random effects model in anteroposterior laxity between the single-bundle and double-bundle ACL reconstruction techniques at 0°, 30°, 60°, and 90° of flexion were 0.99 mm, 0.38 mm, 0.34 mm, and 0.07 mm, respectively. No statistically significant difference was noted between the 2 treatments at all flexion angles. Among the 9 studies that compared the rotational laxity of single-bundle and double-bundle ACL reconstructions, 4 reported that double-bundle reconstruction can provide better rotational control than single-bundle reconstruction. The other 5 studies could not identify any significant difference between the 2 reconstructions in terms of rotational laxity., Conclusions: Both single- and double-bundle treatment options for ACL injury result in similar anteroposterior knee joint laxity at time 0. No conclusive evidence on the superiority of 1 reconstruction technique over the other in terms of rotation laxity can be obtained because of several variations in the experimental protocol and the kinematics used to measure the rotational laxity among the studies., Level of Evidence: Level III, meta-analysis., (Copyright © 2011 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)