Effect of ACL graft material on anterior knee force during simulated in vivo ovine motion applied to the porcine knee: An in vitro examination of force during 2000 cycles

This study determined how anterior cruciate ligament (ACL) reconstruction affected the magnitude and temporal patterns of anterior knee force and internal knee moment during 2000 cycles of simulated gait. Porcine knees were tested using a six degree‐of‐freedom robot, examining three porcine allograft materials compared with the native ACL. Reconstructions were performed using: (1) bone‐patellar tendon‐bone allograft (BPTB), (2) reconstructive porcine tissue matrix (RTM), or (3) an RTM‐polymer hybrid construct (Hybrid). Forces and moments were measured over the entire gait cycle and contrasted at heel strike, mid stance, toe off, and peak flexion. The Hybrid construct performed the best, as magnitude and temporal changes in both anterior knee force and internal knee moment were not different from the native ACL knee. Conversely, the RTM knees showed greater loss in anterior knee force during 2000 cycles than the native ACL knee at heel strike and toe off, with an average force loss of 46%. BPTB knees performed the least favorably, with significant loss in anterior knee force at all key points and an average force loss of 61%. This is clinically relevant, as increases in post‐operative knee laxity are believed to play a role in graft failure and early onset osteoarthritis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1789–1795, 2015.     

Investigating the effects of anterior tibial translation on anterior knee force in the porcine model: Is the porcine knee ACL dependent?

This study sought to determine anterior force in the porcine knee during simulated 6‐degree‐of‐freedom (DOF) motion to establish the role of the anterior cruciate ligament (ACL). Using a 6‐DOF robot, a simulated ovine motion was applied to porcine hind limbs while recording the corresponding forces. Since the porcine knee is more lax than the ovine knee, anterior tibial translations were superimposed on the simulated motion in 2 mm increments from 0 mm to 10 mm to find a condition that would load the ACL. Increments through 8 mm increased anterior knee force, while the 10 mm increment decreased the force. Beyond 4 mm, anterior force increases were non‐linear and less than the increases at 2 and 4 mm, which may indicate early structural damage. At 4 mm, the average anterior force was 76.9 ± 10.6 N (mean ± SEM; p < 0.025). The ACL was the primary restraint, accounting for 80–125% of anterior force throughout the range of motion. These results demonstrate the ACL dependence of the porcine knee for the simulated motion, suggesting this model as a candidate for studying ACL function. With reproducible testing conditions that challenge the ACL, this model could be used in developing and screening possible reconstruction strategies. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:641–646, 2011     

In vivo kinematics of the ACL during weight-bearing knee flexion.

No study has investigated the three-dimensional morphological changes of the anterior cruciate ligament (ACL) during functional activities in vivo. The purpose of this study was to analyze the elongation, rotation (twist), and orientation of the ACL during weight-bearing flexion in five human subjects using dual-orthogonal fluoroscopic images and MR image-based computer models. The ACL consistently decreased in length with flexion. At 90 degrees , the length decreased by 10% compared to its length at full extension. The ACL twisted internally by only 20 degrees at 30 degrees of flexion. The ACL was oriented more vertically (approximately 60 degrees ) and slightly laterally (approximately 10 degrees ) at low flexion angles. These data on in vivo ligament elongation demonstrate that the ACL plays a more important role in lower flexion angles than at higher flexion angles during weight-bearing flexion. These data also suggest that successful ACL reconstruction should not only restore the ligament's elongation behavior, but also its rotational and orientation characteristics, so that normal ACL biomechanics are restored.     

Orientation changes in the cruciate ligaments of the knee during skeletal growth: A porcine model

Musculoskeletal injuries in pediatric patients are on the rise, including significant increases in anterior cruciate ligament (ACL) injuries. Previous studies have found major anatomical changes during skeletal growth in the soft tissues of the knee. Specifically, the ACL and the posterior cruciate ligament (PCL) change in their relative orientation to the tibial plateau throughout growth. In order to develop age‐specific treatments for ACL injuries, the purpose of this study was to characterize orientation changes in the cruciate ligaments of the Yorkshire pig, a common pre‐clinical model, during skeletal growth in order to verify the applicability of this model for pediatric musculoskeletal studies. Hind limbs were isolated from female Yorkshire pigs ranging in age from newborn to late adolescence and were then imaged using high field strength magnetic resonance imaging. Orientation changes were quantified from the magnetic resonance images using image segmentation software. Statistically significant increases were found in the coronal and sagittal angles of the ACL relative to the tibial plateau during pre‐adolescent growth. Additional changes were observed in the PCL angle, Blumensaat angle, intercondylar roof angle, and the aspect ratio of the intercondylar notch. Only the sagittal angle of the ACL relative to the tibial plateau experienced statistically significant changes through late adolescence. The age‐dependent properties of the ACL and PCL in the female pig mirrored results found in female human patients, suggesting that the porcine model may provide a pre‐clinical platform to study the cruciate ligaments during skeletal growth. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2725–2732, 2017.

     

Relationship between altered knee kinematics and subchondral bone remodeling in a clinically translational model of ACL injury

Abnormal joint kinematics are commonly reported in the acute and chronic stages of recovery after anterior cruciate ligament (ACL) injury and have long been mechanistically implicated as a primary driver in the development of posttraumatic osteoarthritis (PTOA). Though strongly theorized, it is unclear to what extent biomechanical adaptations after ACL injury culminate in the development of PTOA, as data that directly connects these factors does not exist. Using a preclinical, noninvasive ACL injury rodent model, our objective was to explore the direct effect of an isolated ACL injury on joint kinematics and the pathogenetic mechanisms involved in the development of PTOA. A total of 32, 16-week-old Long-Evans rats were exposed to a noninvasive ACL injury. Marker-less deep learning software (DeepLabCut) was used to track animal movement for sagittal-plane kinematic analyses and micro computed tomography was used to evaluate subchondral bone architecture at days 7, 14, 28, and 56 following injury. There was a significant decrease in peak knee flexion during walking (p < .05), which had a moderate-to-strong negative correlation (r = ?.59 to ?.71; p < .001) with subchondral bone plate porosity in all load bearing regions of the femur and tibia. Additional comprehensive analyses of knee flexion profiles revealed dramatic alterations throughout the step cycle. This occurred alongside considerable loss of epiphyseal trabecular bone and substantial changes in anatomical orientation. Knee flexion angle and subchondral bone microarchitecture are severely impacted after ACL injury. Reductions in peak knee flexion angle after ACL injury are directly associated with subchondral bone plate remodeling.     

透明质酸预防关节镜下前交叉韧带重建术后膝关节粘连的临床研究

[目的]探讨透明质酸预防关节镜下前交叉韧带重建术后发生膝关节粘连的效果.[方法]选择2009年1月～2010年12月收治的60例行关节镜下前交叉韧带重建术的患者,随机选择30例术后关节腔内注射透明质酸2.5ml作为实验组;另30例常规手术不应用透明质酸作为对照组.随访观察术后6周时膝关节的伸屈活动度,Lysholm评分总改善率及VAS评分.[结果]60例均获随访,术后6周时膝关节活动度,实验组伸屈141.25.±9.98°,对照组伸屈133.75°±8.56.,具有统计学意义(P＜0.05);Lysholm评分总改善率,实验组84.8％,对照组65.4％,具有统计学意义(P＜0.05);VAS评分,实验组4.20±1.15,对照组6.10-1.59,具有统计学意义(P＜0.05).[结论]透明质酸能有效预防前交叉韧带重建术后膝关节粘连的发生.     

智能负重机器人在前交叉韧带重建患者康复训练的应用

目的 探讨下肢智能负重机器人用于前交叉韧带重建患者康复训练的效果。方法 选取行前交叉韧带重建的96例患者作为研究对象,按照入院时间顺序分为对照组和干预组各48例。对照组实施常规康复训练,干预组实施下肢智能负复机器人康复训练,比较两组的干预效果。结果 干预后,干预组膝关节活动度、膝关节功能评分显著优于对照组,疼痛评分显著低于对照组,日常生活活动能力评分显著高于对照组（均P＜0.05）。结论 智能负重机器人应用于前交叉韧带重建术患者康复训练,能有效改善患者膝关节功能,减轻训练疼痛,有助于提高其日常生活活动能力。     

A comparison of cyclic variations in anterior knee laxity,genu recurvatum,and general joint laxity across the menstrual cycle

Changes in anterior knee laxity (AKL), genu recurvatum (GR) and general joint laxity (GJL) were quantified across days of the early follicular and early luteal phases of the menstrual cycle in 66 females, and the similarity in their pattern of cyclic variations examined. Laxity was measured on each of the first 6 days of menses (M1–M6) and the first 8 days following ovulation (L1–L8) over two cycles. The largest mean differences were observed between L5 and L8 for AKL (0.32 mm), and between L5 and M1 for GR (0.56°) and GJL (0.26) (p < 0.013). At the individual level, mean absolute cyclic changes in AKL (1.8 ± 0.7 mm, 1.6 ± 0.7 mm), GR (2.8 ± 1.0°, 2.4 ± 1.0°), and GJL (1.1 ± 1.1, 0.7 ± 1.0) were more apparent, with minimum, maximum and delta values being quite consistent from month to month (ICC_2,3 = 0.51–0.98). Although the average daily pattern of change in laxity was quite similar between variables (Spearman correlation range 0.61 and 0.90), correlations between laxity measures at the individual level were much lower (range ?0.07 to 0.43). Substantial, similar, and reproducible cyclic changes in AKL, GR, and GJL were observed across the menstrual cycle, with the magnitude and pattern of cyclic changes varying considerably among females. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1411–1417, 2010     

In vivo kinematic analysis of cruciate-retaining total knee arthroplasty during weight-bearing and non-weight-bearing deep knee bending

The purpose of the present study was to evaluate the in vivo kinematics of the posterior cruciate ligament-retaining total knee arthroplasty during weight-bearing and non-weight-bearing deep knee bending and compare these 2 different conditions. We evaluated the in vivo kinematics of the knee using fluoroscopy and femorotibial translation relative to the tibia tray by 2-dimensional/3-dimensional registration. In the weight-bearing state, the femoral component showed central pivot and bicondylar posterior rollback pattern. During non-weight-bearing, the movement anteriorly occurred on both the medial and lateral side during early flexion, whereas bicondylar femoral component rollback occurred after that. During non-weight-bearing, both the medial and lateral condyle significantly moved anteriorly compared with the weight-bearing state during early flexion. However, bicondylar femoral rollback occurred under both these conditions.     

New perspectives on ACL injury: On the role of repetitive sub‐maximal knee loading in causing ACL fatigue failure

In this paper, we review a series of studies that we initiated to examine mechanisms of anterior cruciate ligament (ACL) injury in the hope that these injuries, and their sequelae, can be better prevented. First, using the earliest in vitro model of a simulated single‐leg jump landing or pivot cut with realistic knee loading rates and trans‐knee muscle forces, we identified the worst‐case dynamic knee loading that causes the greatest peak ACL strain: Combined knee compression, flexion, and internal tibial rotation. We also identified morphologic factors that help explain individual susceptibility to ACL injury. Second, using the above knee loading, we introduced a possible paradigm shift in ACL research by demonstrating that the human ACL can fail by a sudden rupture in response to repeated sub‐maximal knee loading. If that load is repeated often enough over a short time interval, the failure tended to occur proximally, as observed clinically. Third, we emphasize the value of a physical exam of the hip by demonstrating how limited internal axial rotation at the hip both increases the susceptibility to ACL injury in professional athletes, and also increases peak ACL strain during simulated pivot landings, thereby further increasing the risk of ACL fatigue failure. When training at‐risk athletes, particularly females with their smaller ACL cross‐sections, rationing the number and intensity of worst‐case knee loading cycles, such that ligament degradation is within the ACL's ability to remodel, should decrease the risk for ACL rupture due to ligament fatigue failure. © 2018 The Authors Journal of Orthopaedic Research published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 34:2059–2068, 2016.     

Effect of the iliotibial band on knee biomechanics during a simulated pivot shift test.

The purpose of this study was to evaluate the effect of the iliotibial band (ITB) on the kinematics of anterior cruciate ligament (ACL) intact and deficient knees and also on the in situ force in the ACL during a simulated pivot shift test. A combination of 10 N-m valgus and 5 N-m internal tibial torques was applied to 10 human cadaveric knees at 15 degrees, 30 degrees, 45 degrees, and 60 degrees of flexion using a robotic/universal force-moment sensor testing system. ITB forces of 0, 22, 44, and 88 N were also applied. An 88 N ITB force significantly decreased coupled anterior tibial translation of ACL deficient knees by 32%-45% at high flexion angles, but did not have a significant effect at low flexion angles. Further, an 88 N ITB force significantly decreased in situ forces in the ACL at all flexion angles by 23%-40%. These results indicate that during the pivot shift test, the ITB can improve tibial reduction at high flexion angles while not affecting subluxation at low flexion angles. Additionally, the action of the ITB as an ACL agonist suggests that its use as an ACL graft might hinder knee stability in response to rotatory load.     

Dynamic in vivo three‐dimensional (3D) kinematics of the anterior cruciate ligament/medial collateral ligament transected ovine stifle joint

The objective of this study was to use an ovine stifle joint model to assess the impact of combined transection of the anterior cruciate and medial collateral ligaments on three‐dimensional (3D) joint motion serially over 20 weeks after transection. In vivo 3D kinematics were measured in the right hind limb of eight sheep while walking on a treadmill (accuracy, 0.4 mm ± 0.4 mm, 0.4° ± 0.4°). Five sheep received surgical ligament transection and three sheep received sham surgery without transection. At 2 weeks after transection, average joint flexion at hoof strike was significantly increased (8.9° ± 3.0°), and the tibial position was significantly shifted in the anterior direction relative to the femur during midstance (4.9 mm ± 0.9 mm). By 20 weeks after transection, joint flexion had normalized, but the tibial position was significantly adducted (0.5° ± 0.7°) and shifted in the medial (2.5 mm ± 1.2 mm), anterior (5.8 mm ± 1.9 mm), and superior directions (1.6 mm ± 0.4 mm). At 2 and 20 weeks after surgical intervention, the maximal anterior tibial position was significantly increased during mid‐stance in the transected group (4.9 mm ± 0. 9 mm and 5.8 mm ± 1.9 mm) compared to the sham operated group (0.2 mm ± 0.2 mm and ?0.1 ± 0.1 mm). Although the anterior tibial shift was observed in all transected sheep, a high degree of variability existed between sheep, in the intitial joint position, the magnitude of the early change, the change over time, and the change at 20 weeks. In this situation statistics must be interpreted carefully, and in future studies, individual changes should be assessed in the context of individual pathological changes in order to investigate potential clinical significance. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:660–672, 2008     

Effect of implant lengthening and mode of fixation on knee laxity after ACL reconstruction with an artificial ligament: a cadaveric study

An "apparent" lengthening of the ligament implant, which causes an increase in knee laxity after the reconstruction of the anterior cruciate ligament (ACL) may be due to either slippage of the implant from under the fixation devices, or tunnel migration (due to bone resorption). These two mechanisms are related to the initial ligament placement, implant tensioning, and fixation modes. This cadaveric study simulates, in a controlled experimental situation, the postoperative lengthening of artificial ACL implants, and seeks to quantify the consequent increase in joint laxity. Eight cadaveric right knees, in which the Leeds-Keio artificial ligament was implanted, were tested in a specially constructed apparatus, which allowed the knee joint six degrees of freedom. In each of the tested joints the laxity was measured under several test conditions for two final fixation modes of the implant. The difference between the fixation modes was the application (as in mode B) or not (as in mode A), of a posteriorly directed force of 50 N on the tibia, at the moment of final fixation of the ligament. In both cases a tensile load of 50 N was maintained along the implant. All measurements were taken at flexion angles of 20° and 90° and with controlled implant lengthening of up to 3 mm in 0.5-mm increments. After implantation, adopting fixation mode B resulted in the knee exhibiting an anterior laxity considerably less than the original physiological laxity, compared with that measured after using fixation mode A. Thus at 20° of knee flexion, under an anterior load of 100 N applied on the tibia, adopting fixation mode B, the joint laxity was 2.8 mm smaller than the natural laxity, whereas, for fixation mode A, it was 1.4 mm larger. At 90° of knee flexion, the situation was similar, but with smaller differences. However, the situation was overturned as the implant length was increased. Thus, at 20° of knee flexion, when the implant was lengthened in a range of 1–2 mm, the laxity observed with fixation mode B was similar to that recorded when the ACL was intact, whereas the laxity observed with fixation mode A was about 3–4 mm greater. Similar data were observed at 90° of knee flexion. It appears that fixing the implant finally by applying a tensile load on it while simultaneously pushing the tibia posteriorly could be an effective measure against the possible return of joint laxity. Received: September 12, 2000 / Accepted: January 18, 2001     

Effect of increased quadriceps tensile stiffness on peak anterior cruciate ligament strain during a simulated pivot landing

ACL injury prevention programs often involve strengthening the knee muscles. We posit that an unrecognized benefit of such training is the associated increase in the tensile stiffness of the hypertrophied muscle. We tested the hypothesis that an increased quadriceps tensile stiffness would reduce peak anteromedial bundle (AM‐)ACL relative strain in female knees. Twelve female cadaver knees were subjected to compound impulsive two‐times body weight loads in compression, flexion, and internal tibial torque beginning at 15° flexion. Knees were equipped with modifiable custom springs to represent the nonlinear rapid stretch behavior of a normal and increased stiffness female quadriceps (i.e., 33% greater stiffness). Peak AM‐ACL relative strain was measured using an in situ transducer while muscle forces and tibiofemoral kinematics and kinetics were recorded. A 3D ADAMS? dynamic biomechanical knee model was used in silico to interpret the experimental results which were analyzed using a repeated‐measures Wilcoxon test. Female knees exhibited a 16% reduction in peak AM‐ACL relative strain and 21% reduction in change in flexion when quadriceps tensile stiffness was increased by 33% (mean (SD) difference: 0.97% (0.65%), p = 0.003). We conclude that increased quadriceps tensile stiffness reduces peak ACL strain during a controlled study simulating a pivot landing. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:423–430, 2014.

     

骨洗方联合持续被动活动治疗膝关节镜下前交叉韧带重建术后关节僵硬

目的观察骨洗方联合持续被动活动（CPM）治疗膝关节前交叉韧带（ACL）重建术后关节僵硬的疗效。方法对我院2009年1月至2010年3月24例（24膝）膝关节镜下ACL重建术后关节僵硬患者,随机分为两组（A组、B组）,每组12例,A组给予中药骨洗方（由薄荷、桂枝、半枫荷、两面针、红花、宽筋藤等组成）熏洗联合CPM训练,B组仅进行CPM训练,定期随访,以Lysholm膝关节功能评估系统（0-100分）和膝关节活动度（ROM）分别评估膝关节功能。结果 24例患者均获得随访,A组随访时间6-12个月,平均随访10个月,B组随访时间7-12个月,平均10.5个月。A组ROM由治疗前78.6°±16.2°（62-95°）,提高到治疗后125.5°±12.1°（112-135°）,差别有统计学意义（t=8.035,P〈0.001）。B组由治疗前80.2°±13.7°（65-91°）提高到治疗后115.4°±10.1°（102-131°）,差别有统计学意义（t=7.164,P〈0.001）。A、B组治疗前ROM无统计学差异（t=0.261,P〉0.05）,治疗后ROM有统计学差异（t=2.220,P〈0.05）。A组Lysholm评分由治疗前74.3±5.8,提高到治疗后86.7±6.5,差别有统计学意义（t=4.931,P〈0.001）。B组Lysholm评分由治疗前72.7±6.3,提高到治疗后81.5±5.5,差别有统计学意义（t=3.645,P〈0.001）。A、B组治疗前Lysholm评分无统计学差异（t=0.647,P〉0.05）,治疗后Lysholm评分有统计学差异（t=2.116,P〈0.05）。两组无一例患者出现皮肤过敏等并发症。结论中药骨洗方熏洗联合CPM训练对膝关节镜下ACL重建术后关节僵硬患者的膝关节活动功能恢复有明显的促进作用,且效果优于单纯行CPM训练。     

The effect of tibial polyethylene insert design on range of motion: evaluation of in vivo knee kinematics by a computerized navigation system during total knee arthroplasty

Computer-assisted navigation for total knee arthroplasty offers the unique opportunity to assess in vivo knee kinematics during surgery and implement changes whenever appropriate. Using a computerized navigation system, the effect of 2 tibial polyethylene insert designs on knee kinematics in general and knee range of motion (ROM) in particular was evaluated in 37 knee arthroplasties in 30 patients. The Scorpioflex tibial insert was found to provide a significant increase in mean extension, mean flexion, and overall ROM of the knee compared with the standard tibial insert (P<.005) without affecting knee ligamentous balance. Navigation is a very effective and useful tool for intraoperative assessment of knee kinematics and accurate recording of ROM. Based on the information obtained from the navigation software, the surgeon can implement changes in selection of the knee components with beneficial effects in knee kinematics in general and knee ROM in particular. This may, in turn, translate to better clinical outcome of the knee arthroplasty.     

In situ force in the anterior cruciate ligament,the lateral collateral ligament,and the anterolateral capsule complex during a simulated pivot shift test

The role of the anterolateral capsule complex in knee rotatory stability remains controversial. Therefore, the objective of this study was to determine the in situ forces in the anterior cruciate ligament (ACL), the anterolateral capsule, the lateral collateral ligament (LCL), and the forces transmitted between each region of the anterolateral capsule in response to a simulated pivot shift test. A robotic testing system applied a simulated pivot shift test continuously from full extension to 90° of flexion to intact cadaveric knees (n = 7). To determine the magnitude of the in situ forces, kinematics of the intact knee were replayed in position control mode after the following procedures were performed: (i) ACL transection; (ii) capsule separation; (iii) anterolateral capsule transection; and (iii) LCL transection. A repeated measures ANOVA was performed to compare in situ forces between each knee state (*p < 0.05). The in situ force in the ACL was significantly greater than the forces transmitted between each region of the anterolateral capsule at 5° and 15° of flexion but significantly lower at 60°, 75°, and 90° of flexion. This study demonstrated that the ACL is the primary rotatory stabilizer at low flexion angles during a simulated pivot shift test in the intact knee, but the anterolateral capsule plays an important secondary role at flexion angles greater than 60°. Furthermore, the contribution of the “anterolateral ligament” to rotatory knee stability in this study was negligible during a simulated pivot shift test. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:847–853, 2018.