The effect of anterior cruciate ligament graft rotation on knee biomechanics

Tang

et al. 2021

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Purpose An understanding of the behavior of a new ACL graft in the femoral tunnel during knee motion and external loading can provide information pertinent to graft healing, tunnel enlargement, and graft failure. The purpose of the study was to measure the percentage of the tunnel illed by the graft and determine the amount and location of the graft-tunnel contact with knee motion and under external knee loads. Methods Single bundle anatomical ACL reconstruction was performed on six cadaveric knees. Specimens were positioned with a robotic testing system under: (1) passive lexion-extension, (2) 89-N anterior and posterior tibial loads, (3) 5-N m internal and external torques, and (4) 7-N m valgus moment. The knees were then dissected, repositioned by the robot and the geometry of the femoral tunnel and graft were digitized by laser scanning. The percentage of tunnel illed and the contact region between graft and tunnel at the femoral tunnel aperture were calculated. ResultsThe graft occupies approximately 70% of the femoral tunnel aperture and anterior tibial loading tended to reduce this value. The graft contacted about 60% of the tunnel circumference and the location of the graft-tunnel contact changed signiicantly with knee lexion. Conclusion This study found that the graft tends to rotate around the tunnel circumference during knee lexion-extension and contract under knee loading. The "windshield-wiper" and "bungee cord" efect may contribute to femoral tunnel enlargement, afect graft healing, and lead to graft failure. There can be a considerable motion of the graft in the tunnel after surgery and appropriate rehabilitation time should be allowed for graft-tunnel healing to occur. To reduce graft motion, consideration should be given to interference screw ixation or a graft with bone blocks, which may allow an earlier return to activity.

Section: Methodsmentioning

confidence: 99%

ACL graft with extra-cortical fixation rotates around the femoral tunnel aperture during knee flexion

Zhu

Tang

et al. 2021

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“…A custom MATLAB program with a multitask operating system (Math Works Inc., Natick, Massachusetts, USA) was utilized to monitor knee kinematics and calculate the in‐situ forces of the ACL and the reconstructed graft, with high test‐retest reliability. [2, 27, 29, 35, 41, 42, 44, 45] During the experiment, this testing system was operated in both the force‐ and displacement‐control modes. With the tibia was attached to the robot while the femur was secured to a fixed platform, the passive flexion–extension path from FE to 90° of knee flexion was found by minimizing the external forces and moments applied to the joint at 0.5° increments of flexion [35].…”

Section: Methodsmentioning

confidence: 99%

“…Since the focus of this study was on the lateral meniscal state and not on the ACL reconstruction, which has been well studied, the gold standard that was used was for comparison was the ACLR knee with an intact meniscus. Two different external loads were applied to the knees during testing: (1) an 89‐N anterior tibial load, a simulated KT1000 test, to test anterior tibial translation (ATT) (mm) at full extension (FE), 15°,30°, 60° and 90° of knee flexion [41, 45], (2) a combined 5.0 Nm internal tibial and 7.0 Nm valgus torque, a simulated pivot‐shift test, was applied to the specimen at full extension and at FE, 15° and 30° of knee flexion [17, 44].…”

Section: Methodsmentioning

confidence: 99%

Partial meniscectomy does not affect the biomechanics of anterior cruciate ligament reconstructed knee with a lateral posterior meniscal root tear

Tang

Wang

et al. 2020

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Purpose The purpose of this study was to determine the effects of a lateral meniscus posterior root tear, partial meniscectomy, and total meniscectomy on knee biomechanics in the setting of anterior cruciate ligament (ACL) reconstruction. Methods Thirteen fresh-frozen cadaver knees were tested with a robotic testing system under an 89.0-N anterior tibial load at full extension (FE), 15°, 30°, 60° and 90° of knee flexion and a simulated pivot-shift loading (7.0 Nm valgus and 5.0 Nm internal tibial rotation) at FE, 15° and 30° of knee flexion. Anterior tibial translation (ATT) and the in-situ force of ACL graft under the different loadings were measured in four knee states: (1) ACL reconstruction with intact lateral meniscus (Intact meniscus), (2) ACL reconstruction with lateral meniscal posterior root tear (Root tear), (3) ACL reconstruction with lateral posterior partial meniscectomy (Partial meniscectomy) and (4) ACL reconstruction with total lateral meniscectomy (Total meniscectomy). Results Under anterior tibial loading, compared with an intact meniscus, root tear significantly increased ATT at 15° and 30° of knee flexion (p < 0.05) and partial meniscectomy had almost same increased ATT as with root tear at any knee flexion between FE and 90°. Under simulated pivot-shift loading, total meniscectomy increased ATT compared with intact meniscus, root tear, partial meniscectomy at FE (p < 0.05). Conclusion Under anterior tibial and simulated pivot-shift loading, partial meniscectomy has no significant effect on the stability of ACL-reconstructed knee with lateral meniscal posterior root tear, while total meniscectomy increased laxity at less than 30° of knee flexion. Clinically, in cases of irreparable meniscal root tears or persistent pain a partial meniscectomy can be considered in the setting of ACL reconstruction.

“…The data were analyzed using one‐way repeated‐measures ANOVA (SPSS Version 24, IBM SPSS Inc.) with knee state as a factor with Bonferroni correction and statistical significance was set at p < 0.05. To determine the number of test samples, an a priori power analysis was performed (G*power 3.1.9.2) using a 2‐tailed, paired, t test and a significance level of 0.05, a power of 0.80 and a hypothesized effect size of d = 1.0 which resulted in n = 10 samples [34]. All data are given as mean and standard deviation.…”

Section: Methodsmentioning

confidence: 99%

Arthroscopic centralization restores residual knee laxity in ACL-reconstructed knee with a lateral meniscus defect

Nakamura

Linde

et al. 2019

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PurposeThe aim of this study was to evaluate the effects of knee biomechanics with an irreparable lateral meniscus defect using the centralization capsular meniscus support procedure in the setting of the ACL‐reconstructed knee in a porcine model. The hypothesis is the arthroscopic centralization will decrease the laxity and rotation of the ACL‐reconstructed knee. MethodsTwelve fresh‐frozen porcine knees were tested using a robotic testing system under the following loading conditions: (a) an 89.0 N anterior tibial load; (b) 4.0 N m internal and external rotational torques. Anatomic single‐bundle ACL reconstruction with a 7 mm‐diameter bovine extensor tendon graft was performed. A massive, middle segment, lateral meniscus defect was created via arthroscopy, and arthroscopic centralization was performed with a 1.4 mm anchor with a #2 suture. The LM states with ACL reconstruction evaluated were: intact, massive middle segment defect and with the lateral meniscus centralization procedure. ResultsThe rotation of the ACL reconstructed knee with the lateral meniscus defect was significantly higher than with the centralized lateral meniscus under an external rotational torque at 30° of knee flexion, and under an internal rotational torque at 30° and 45° of knee flexion. There were no systematic and consistent effects of LM centralization under anterior tibial translation. ConclusionsIn this porcine model, the capsular support of middle segment of the lateral meniscus using arthroscopic centralization improved the residual rotational laxity of the ACL‐reconstructed knee accompanied with lateral meniscus dysfunction due to massive meniscus defect. This study quantifies the benefit to knee kinematics of arthroscopic centralization by restoring the lateral meniscal function.