Medial collateral ligament insertion site and contact forces in the ACL-deficient knee.

The objectives of this research were to determine the effects of anterior cruciate ligament (ACL) deficiency on medial collateral ligament (MCL) insertion site and contact forces during anterior tibial loading and valgus loading using a combined experimental-finite element (FE) approach. Our hypothesis was that ACL deficiency would increase MCL insertion site forces at the attachments to the tibia and femur and increase contact forces between the MCL and these bones. Six male knees were subjected to varus-valgus and anterior-posterior loading at flexion angles of 0 degrees and 30 degrees. Three-dimensional joint kinematics and MCL strains were recorded during kinematic testing. Following testing, the MCL of each knee was removed to establish a stress-free reference configuration. An FE model of the femur-MCL-tibia complex was constructed for each knee to simulate valgus rotation and anterior translation at 0 degrees and 30 degrees, using subject-specific bone and ligament geometry and joint kinematics. A transversely isotropic hyperelastic material model with average material coefficients taken from a previous study was used to represent the MCL. Subject-specific MCL in situ strain distributions were used in each model. Insertion site and contact forces were determined from the FE analyses. FE predictions were validated by comparing MCL fiber strains to experimental measurements. The subject-specific FE predictions of MCL fiber stretch correlated well with the experimentally measured values (R2 = 0.95). ACL deficiency caused a significant increase in MCL insertion site and contact forces in response to anterior tibial loading. In contrast, ACL deficiency did not significantly increase MCL insertion site and contact forces in response to valgus loading, demonstrating that the ACL is not a restraint to valgus rotation in knees that have an intact MCL. When evaluating valgus laxity in the ACL-deficient knee, increased valgus laxity indicates a compromised MCL.     

Double-band reconstruction of the ACL using a synthetic implant: a cadaveric study of knee laxity

In this study, the anterior laxity and internal rotation of five cadaveric knee joints were compared when the anterior cruciate ligament (ACL) was intact, after its reconstruction with the anteromedial band (AMB) only, then after its reconstruction with the double band, with the posterolateral band (PLB) tensioned first at 20° and then at 90°, and finally with the ACL resected. The tests were performed using a mechanical apparatus that allowed the joint 6° of freedom and also the application of external loads and torques on the tibia. The loads used were 50, 90, and 130N for the anterior laxity test, and a torque of 2, 3, and 4Nm in the internal rotation test. In all cases, laxity with double-band reconstruction was closer to the natural value than when it was constructed with the AMB only. In some cases, double-band reconstruction imposed a higher constraint on the joint than did the natural ACL. Measurement of the residual tension on the PLB after its final anchoring was also performed during passive flexion. This test revealed a high tension on this band with the knee in hyperextension, followed by a decrease in value through to 45° and a slight increase at 90°, thus following a similar trend to that of the natural PLB.     

Roles of the anterior cruciate ligament and the medial collateral ligament in preventing valgus instability

Both the medial collateral ligament (MCL) and the anterior cruciate ligament (ACL) are reported to prevent valgus instability of the knee. In this study, the anatomical mechanisms by which these ligaments prevent valgus instability were experimentally investigated. The valgus rotation angle and the magnitude of the medial joint space opening were measured in six cadaveric knees, using biplanar photography before and after the MCL and/or the ACL were severed. A significant increase in the valgus rotation angle and a large medial joint space opening were observed when the MCL was severed. An increase in the valgus rotation angle was also observed when the ACL was severed, but only a small medial joint space opening was present. The increase in the valgus rotation angle after ACL severance was nearly parallel to the increase in the internal rotation of the tibia. Thus, we concluded that both ligaments function to prevent valgus instability, but that the anatomical reasons for their function are different. The MCL prevents valgus instability by stopping an opening in the medial joint space. The ACL, on the other hand, prevents the internal rotation of the tibia. When the ACL is severed, the internal rotation increases, and causes the valgus rotation angle to also increase, despite the presence of only a small medial joint space opening. Received: May 16, 2000 / Accepted: August 3, 2000     

ACL femoral avulsion repair using suture pull-out technique: A case series ofthirteen patients

Purpose

Anterior cruciate ligament (ACL) repair was first described in the mid 1900's. However, due to poorly selected patients led to unsatisfactory early results. We aim to study the outcome of ACL repair in a carefully selected cohort.

Differential sensitivity to NO-induced apoptosis between anterior cruciate and medial collateral ligament cells

It is well known that the anterior cruciate ligament (ACL) of the knee joint has poorer healing responses than the medial collateral ligament (MCL). Nitric oxide (NO) induces free radicals and plays a key role in the induction of apoptosis in various wound-healing models. We hypothesized that the poor healing response of the ACL may be ascribed to high susceptibility to apoptosis, and we investigated the difference in susceptibility to apoptosis between ACL and MCL cells after treatment with sodium nitroprusside, a NO donor. Apoptosis was evaluated by phase contrast microscopy, electron microscopy, DNA gel electrophoresis, and flow cytometric analysis. Although morphological changes and DNA ladders were observed in both ACL and MCL cells after 2mM sodium nitroprusside treatment, ACL cells were more prone to apoptosis at 1mM. Based on flow cytometric analysis, DNA fragmentation at 1mM sodium nitroprusside was significantly greater in ACL cells than in MCL cells (58.6% ± 1.6% vs. 11.9% ± 2.2%). Caspase-3 inhibitor (Ac-Asp-Glu-Val-Asp-CHO) and caspase-9 inhibitor (Ac-Leu-Glu-His-Asp-CHO) completely inhibited this DNA fragmentation. In conclusion, the ACL and MCL cells exhibit essential differences, and the differential sensitivity to NO-induced apoptosis between the ACL and MCL cells may be a reflection of these differences.     

驾驶摩托车致膝关节前内侧旋转不稳定的手术治疗

目的探讨手术治疗驾驶摩托车致膝关节前内侧旋转不稳定(antero-medial rotatory instability,AMRI)的效果。方法 2007年6月-2009年12月,收治32例驾驶摩托车致膝关节AMRI患者。男28例,女4例;年龄20～50岁,平均35.5岁。受伤至手术时间5～10 d,平均7 d。前交叉韧带(anterior cruciate ligament,ACL)均于胫骨髁间嵴附着点处撕脱;内侧副韧带(medial collateral ligament,MCL)损伤部位:中央部位19例,股骨内侧髁部10例,胫骨内侧髁部3例。均为闭合损伤。采用钢丝固定胫骨髁间嵴撕脱骨折块,同时修复MCL治疗。结果术后1例发生切口红肿伴少量渗液,其余患者切口均Ⅰ期愈合。5例发生膝关节创伤性关节炎,经相应处理后好转。术后患者均获随访,随访时间16～22个月,平均18.5个月。X线片检查示胫骨髁间嵴骨折均于术后5～8周愈合,平均6周。末次随访时,患者膝关节伸膝均达0°;屈膝110～170°,平均155°。采用国际膝关节文献委员会(IKDC)分级标准评价膝关节功能,获A级24例,B级6例,C级1例,D级1例。Lysholm膝关节评分为(85.93±3.76)分,明显高于术前的(37.54±3.43)分,差异有统计学意义(t=53.785,P=0.000)。结论驾驶摩托车致膝关节AMRI,采用钢丝固定胫骨髁间嵴撕脱骨折块,同时修复MCL治疗,结合术后早期功能锻炼,近期疗效满意,远期疗效尚需随访观察。     

Does the peak torque of the hamstring and quadriceps muscles affect the knee laxity measurements in male patients with anterior cruciate ligament rupture?

The aim of the study was to examine whether the peak torque of the hamstring and quadriceps muscles affects the anterior knee laxity measurements in male patients. The study comprised 45 male patients who had a chronic unilateral anterior cruciate ligament (ACL) rupture. Preoperatively, one experienced physiotherapist performed all the KT-1000 examinations. The anterior displacement was registered at 89 Newton. Immediately after the KT-1000 examination, an isokinetic concentric peak torque measurement was performed at 60°/s for both the hamstring and quadriceps muscles. The anterior displacement was significantly larger in the ACL-ruptured knees compared with the noninjured knees (p < 0.001). Patients with strong hamstring muscles on the injured side displayed significantly less knee laxity compared with patients with less strength (p = 0.018). There was an inverse correlation between the peak torque of the hamstring muscles and the KT-1000 anterior laxity measurements in the ACL-ruptured knees (rho = −0.37, p = 0.01). We conclude that male patients with strong hamstring muscles display smaller KT-1000 laxity measurements than patients with less strength. Received: 22 January 2001/Accepted: 24 January 2001     

Anterior cruciate ligament laxity related to the menstrual cycle: an updated systematic review of the literature

Objectives:

The purpose of this study was to conduct a systematic review regarding the purported differences in anterior cruciate ligament (ACL) laxity throughout the course of the menstrual cycle.

Methods:

A systematic review was performed by searching electronic databases, along with hand-searching of journals and reference tracking for any study that assessed ACL integrity throughout the menstrual cycle from 1998 until 2011. Studies that met the pre-defined inclusion criteria were evaluated using the Modified Sackett Score (MSS) instrument that assessed their methodological quality.

Results:

Thirteen articles out of a possible 28 met the inclusion criteria.

Conclusions:

This systematic review found 13 clinical trials investigating the effect of the menstrual cycle on ACL laxity. There is evidence to support the hypothesis that the ACL changes throughout the menstrual cycle, with it becoming more lax during the pre-ovulatory (luteal) phase. Overall, these reviews found statistically significant differences for variation in ACL laxity and injury throughout the menstrual cycle, especially during the pre-ovulatory phase. Female athletes may need to take precautions in order to reduce the likelihood of ACL injury. However, the quality of the assessments was low and the evidence is still very limited. More and better quality research is needed in this area.     

Posttraumatic incarceration of medial collateral ligament into knee joint with anterior cruciate ligament injury

Medial collateral ligament of the knee is an important coronal stabiliser and often injured in isolation or as combination of injuries. The article reports a case of incarcerated medial collateral ligament (MCL) injury in combination with anterior cruciate ligament (ACL) injury in 20 year old male who presented to us 4 weeks after injury. Clinical examination and MRI was correlated to complete ACL tear with torn distal MCL and incarceration into the joint. Patient was taken up for ACL hamstring graft reconstruction with mini-arthrotomy and repair of the torn MCL. Patient was followed up with dedicated rehabilitation protocol with good functional results. At one year follow-up, patient exhibited full range of motion with negative Lachman, Pivot shift and valgus stress tests. This article highlights the rare pattern of MCL tear and also reviews the literature on this pattern of injury.     

Correlation of healing capacity with vascular response in the anterior cruciate and medial collateral ligaments of the rabbit.

In clinical terms, functional recovery after anterior cruciate ligament (ACL) injury is generally poorer than after medial collateral ligament (MCL) injury. In experimental studies of injury, the early phases of ligament healing require an augmented blood supply. We hypothesized that the differences in healing properties of the ACL and MCL would be reflected in the magnitude of their vascular responses to partial injury. This study is the first to quantify and define the time course of changes in blood flow and vascular volume following hemisection of the rabbit ACL and MCL.Adult female rabbits were assigned to control, sham operation, ACL hemisection or MCL hemisection groups. Standardized ACL or MCL injuries were surgically induced. About 2, 6 or 16 weeks later, blood flow and vascular volume of the ACL and MCL were measured.The MCL of the rabbit responded to hemisection with a large significant increase in blood flow and a substantial angiogenic response associated with inflammation and scar formation. During subsequent matrix remodelling, blood flow and vascular volume returned towards control values. In contrast, the ACL showed only a 2-fold increase in vascular volume, no increase in blood flow and atrophied after hemisection. The superior capacity of the MCL to increase its blood supply through angiogenesis and increased flow is essential for ligament healing to occur, and may be the major difference in healing potential between the ACL and MCL.     

Primary repair plus intra-articular iliotibial band augmentation in the treatment of an acute anterior cruciate ligament rupture

Between September 1987 and November 1989, we treated 90 consecutive patients with an acute anterior cruciate ligament (ACL) rupture with the multiple suture technique and iliotibial band augmentation. Seventy of these patients were re-examined 2 to 5 years after the operation (mean 3.5 years), the examination consisting of a questionnaire, clinical examination, laxity tests with the KSS machine (Acufex), radiological examination and isokinetic muscle strength testing (Cybex 6000). There were 32 men and 38 women (mean age 34 years). The injury was sustained in sports in 44 (63%) cases, and the sports most frequently involved were downhill skiing (18 cases), soccer (9 cases) and volleyball (5 cases). Of the injuries, 38 were isolated ACL ruptures and 31, ACL ruptures combined with a medial CL rupture. In 9 cases, an additional meniscus injury and in one case an additional posterior CL - lateral CL rupture was found. At the follow-up, 55 patients (79%) were satisfied with the end result, and according to our objective functional criteria 55 (79%) had an excellent or good outcome. According to the Lysholm score, 53 (76%) patients were excellent or good ( 82 points). In the Lachman test, 29 knees (41%) were completely stable. The Lachman test was mildy positive in 40 knees (57%) (36 had 1+ laxity and 4, 2+ laxity), and one patient had 3+ laxity with a hard end-point. Similarly, the anterior drawer test was negative in 53 knees (76%); and the other 17 (24%) had mild laxity (16 had 1+ laxity and 1, 2+ laxity). The total anterior-posterior laxity measured with the KSS averaged 9.7 ± 3.5 mm in the injured knee and 7.3 + 3.0 mm in the uninjured knee (the laxity measured at a knee angle of 20° of flexion). Corresponding values at a knee angle of 90° of flexion were 6.1 ± 2.4 mm and 4.7 ± 1.9 mm, respectively. The pivot shift test was negative in 62 patients (89%) and l+ positive in the remaining 8 patients (11%). Fifty-eight patients (83%) had full knee extension and 40 patients (57%), full knee flexion. Compared with the uninjured knee, the operated knees showed an average 14% strength deficit in isokinetic knee extension and 6% deficit in flexion at the speed of 60°/s. At the speed of 180°/s, the corresponding deficits were 8% and 4%, respectively. Of the 44 patients who were active in sport before the injury, 40 (91%) were able to return to sports. A flexion deficit of 5° or more was associated with thigh muscle atrophy (P < 0.05) and quadriceps weakness, both at the slow speed (P < 0.05) and high speed (P < 0.001) of the isokinetic movement. In conclusion, in an acute rupture of the ACL, primary repair of the ligament with intraarticular iliotibial band augmentation seems to be a good method to restore the functional capacity of the injured knee.     

Gender differences in passive knee biomechanical properties in tibial rotation

The anterior cruciate ligament (ACL) is the most commonly injured knee ligament with the highest incidence of injury in female athletes who participate in pivoting sports. Noncontact ACL injuries commonly occur with both internal and external tibial rotation. ACL impingement against the lateral wall of the intercondylar notch during tibial external rotation and abduction has been proposed as an injury mechanism, but few studies have evaluated in vivo gender‐specific differences in laxity and stiffness in external and internal tibial rotations. The purpose of this study was to evaluate these differences. The knees of 10 male and 10 female healthy subjects were rotated between internal and external tibial rotation with the knee at 60° of flexion. Joint laxity, stiffness, and energy loss were compared between male and female subjects. Women had higher laxity (p = 0.01), lower stiffness (p = 0.038), and higher energy loss (p = 0.008) in external tibial rotation than did men. The results suggest that women may be at greater risk of ACL injury resulting from impingement against the lateral wall of the intercondylar notch, which has been shown to be associated with external tibial rotation and abduction. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:937–944, 2008     

Knee Abduction Affects Greater Magnitude of Change in ACL and MCL Strains Than Matched Internal Tibial Rotation In Vitro

Background

Anterior cruciate ligament (ACL) injures incur over USD 2 billion in annual medical costs and prevention has become a topic of interest in biomechanics. However, literature conflicts persist over how knee rotations contribute to ACL strain and ligament injury. To maximize the efficacy of ACL injury prevention, the effects of underlying mechanics need to be better understood.

Questions/purposes

We applied robotically controlled, in vivo-derived kinematic stimuli to the knee to assess ligament biomechanics in a cadaver model. We asked: (1) Does the application of abduction rotation increase ACL and medial collateral ligament (MCL) strain relative to the normal condition? (2) Does the application of internal tibial rotation impact ACL strain relative to the neutral condition? (3) Does combined abduction and internal tibial rotation increase ligament strain more than either individual contribution?

Methods

A six-degree-of-freedom robotic manipulator was used to position 17 cadaveric specimens free from knee pathology outside of low-grade osteoarthritis (age, 47 ± 8 years; 13 males, four females) into orientations that mimic initial contact recorded from in vivo male and female drop vertical jump and sidestep cutting activities. Four-degree rotational perturbations were applied in both directions from the neutral alignment position (creating an 8° range) for each frontal, transverse, and combined planes while ACL and MCL strains were continuously recorded with DVRT strain gauges implanted directly on each ligament. Analysis of variance models with least significant difference post hoc analysis were used to assess differences in ligament strain and joint loading between sex, ligament condition, or motion task and rotation type.

Results

For the female drop vertical jump simulation in the intact knee, isolated abduction and combined abduction/internal rotational stimuli produced the greatest change in strain from the neutral position as compared with all other stimuli within the ACL (1.5% ± 1.0%, p ≤ 0.035; 1.8% ± 1.3%, p ≤ 0.005) and MCL (1.8% ± 1.0%, p < 0.001; 1.6% ± 1.3%, p < 0.001) compared with all other applied stimuli. There were no differences in mean peak ACL strain between any rotational stimuli (largest mean difference = 2.0%; 95% confidence interval [CI], ?0.9% to 5.0%; p = 0.070). These trends were consistent for all four simulated tasks. Peak ACL strain in the intact knee was larger than peak MCL strain for all applied rotational stimuli in the drop vertical jump simulations (smallest mean difference = 2.1%; 95% CI, ?0.4% to 4.5%; p = 0.047).

Conclusions

Kinematically constrained cadaveric knee models using peak strain as an outcome variable require greater than 4° rotational perturbations to elicit changes in intraarticular ligaments.

Clinical Relevance

Because combined rotations and isolated abduction produced greater change in strain relative to the neutral position for the ACL and MCL than any other rotational stimuli in this cadaver study, hypotheses for in vivo investigations aimed toward injury prevention that focuses on the reduction of frontal plane knee motion should be considered. Furthermore, reduced strain in the MCL versus the ACL may help explain why only 30% of ACL ruptures exhibit concomitant MCL injuries.

     

膝内侧半月板“湾征”对内侧副韧带断裂的诊断意义

目的内侧副韧带损伤后,关节镜下可见内侧半月板上滑膜缘完全显示,类似海湾形状,称为"海湾全景征"(简称"湾征"),判断其作为诊断膝内侧副韧带断裂标志体征的可靠性及意义。方法 2007年3月-2011年3月,纳入59例MRI检查提示内侧副韧带断裂患者作为观察组,其中男38例,女21例;年龄16～39岁,平均23.2岁;单纯内侧副韧带断裂12例,合并外侧半月板损伤16例,前交叉韧带损伤27例,前、后交叉韧带损伤3例,髌骨脱位1例。68例MRI检查提示无内侧副韧带断裂患者作为对照组,其中男45例,女23例;年龄25～49岁,平均31.8岁;前交叉韧带损伤38例,前、后交叉韧带损伤4例,前交叉韧带合并外侧半月板损伤26例。两组治疗前后行关节镜探查比较"湾征"出现情况。结果观察组膝内侧副韧带修复重建前关节镜探查均见"湾征",明确内侧副韧带断裂;修复重建后"湾征"消失。对照组交叉韧带重建前后均未见"湾征"。结论 "湾征"可作为关节镜下膝内侧副韧带断裂的诊断指征,以及术中韧带修复重建成功与否的判断依据。     

Vascular physiology and long-term healing of partial ligament tears.

Functional outcomes of anterior cruciate ligament (ACL) injury are generally poorer than those of medial collateral ligament (MCL) tears. Following ligament damage, all phases of ligament healing require an adequate blood supply. We hypothesized that the differences in healing properties of the ACL and MCL would reflect their vascular responses to joint injury. This paper examines the long-term changes in blood flow and vascular volume of rabbit knee ligaments after direct injury, and under conditions of chronic joint instability induced by section of the posterior cruciate ligament (PCL). Standardized injuries were surgically induced in adult rabbit knee ligaments: partial MCL transection, partial ACL transection, or complete PCL transection (joint instability). Sixteen weeks later the blood flow and vascular volume of the ACL and MCL were measured and compared to control and sham-operated animals. Direct ligament injury induced significant increases in standardized blood flow and vascular volume of both ACL and MCL after 16 weeks; however, the vascular volume of the ACL was not higher than the control levels in the MCL. We conclude that direct injury to both the anterior cruciate and MCLs induces long-term physiological responses. Joint laxity is a common sequel to PCL injury. Chronic joint laxity failed to induce adaptive vascular responses in the ACL, while the MCL shows significant amplification of blood supply. Although both MCL and ACL showed increased weight after PCL transection, the lack of a long-term vascular response in the ACL may be a major factor in its the diminished healing potential.     

Treatment of the anterior cruciate ligament-absent knee with associated meniscal tears. Instrumented testing and clinical evaluation of two patient groups

The UCLA instrumented clinical testing apparatus was used to measure postoperative stiffness and laxity for two groups of patients with documented chronic absence of the anterior cruciate ligament (ACL) and associated meniscal tears. Group 1 consisted of 76 patients (average age, 25 years) who had undergone anterior cruciate substitution using the torn meniscus, and a second group of 34 patients (average age, 31 years) who had partial meniscectomy alone without ACL substitution. Subjective and objective evaluations were significantly higher and symptoms of pain and buckling significantly lower in the substitution group. In addition, 29% of Group 1 and only 7% of Group 2 patients were able to return to their preinjury sports without limitations, while 5% of the former and 12% of the latter could not return to any sport. At 90 degrees of flexion, there were no significant differences in stiffness or laxity between the patient groups. At 20 degrees of flexion and neutral foot rotation, the meniscal substitution group had an average of 1.4 mm less side-to-side laxity difference than the partial meniscectomy patients; 51% of the substituted patients still had an injured knee laxity that was at least 2 mm greater than the uninjured knee, as contrasted to 67% of the partial meniscectomy patients who exceeded this upper limit of the normal range. At 20 degrees, anterior stiffness of the injured knees of the substitution patients was 28% greater than the injured knees of the partial meniscectomy group; 42% of the substituted patients had an injured knee stiffness within the normal range, while only 18% of the partial meniscectomy patients fell within normal limits. There were no statistical correlations of stiffness or laxity values with clinical scores or patient symptomatology in either group.     

Pressure distribution at the knee joint

Traumata or repetitive microtraumata, malalignment with varus or valgus deviation, or chronic joint instability are discussed in the aetiology of osteoarthritis and osteochondritis dissecans of the knee. Biomechanical factors influencing the patterns of pressure distribution at the articular surface and the subchondral bone are suggested to be most important in the pathogenesis. Consequently, the patterns of pressure distribution at the femoral condyles of weight-bearing knee joints were investigated in a cadaveric biostatic model. The pressure in the articular joint space was evaluated with pressure-sensitive films of the knee in different joint positions in the coronal plane (10° varus, 10° valgus, and neutral position) without and with medial collateral ligament (MCL), lateral CL (LCL), MCL + anterior cruciate ligament (ACL) or LCL + ACL ligament division. Results demonstrated that the location of the contact area and the peak pressure depended on the joint position and stage of ligamentous division. Without ligament division, a maximum peak pressure was observed at the medial condyle in the neutral and varus positions. Only in the valgus position did the lateral condyle show a higher peak of pressure than the medial condyle. Ligament division of the LCL and LCL + ACL resulted in an increase of peak pressure at the medial condyle, particularly in the varus position. Division of the MCL and MCL + ACL ligament complex reduced the differences between the medial and lateral condyle. In the valgus position, the peak pressure was significantly higher at the lateral condyle. The absolute maximum peak pressure was measured in the varus position at the medial condyle after division of the LCL and ACL. The absolute minimum was found in the valgus position at the medial condyle after division of the MCL and ACL. No significant change of the location of the centre of peak pressure area was observed due to the different joint positions.Presented in part at the 21st Congress of the Austrian Society of Orthopaedic Surgery, 5 May–1 June 1991, Linz, Austria     

Anterior cruciate ligament reconstruction and physiological joint laxity: earliest changes in joint stability and stiffness after reconstruction

Physiological joint laxity is an important element of normal knee joint function, providing smooth joint movement. However, the objective evaluation of post-operative results after knee ligament surgery is usually based primarily on stability and range of motion, and joint laxity has been ignored. In this study, we measured the joint stiffness of 82 knees undergoing anterior cruciate ligament (ACL) reconstruction with the Leeds-Keio artificial ligament, before the operation, immediately after the operation, and finally when the full range of motion was achieved postoperatively; changes in joint laxity after the ACL reconstruction were investigated. Before the operation, joint laxity was greater than that of the normal side (P < 0.01), but immediately after the operation it diminished compared not only with that observed preoperatively, but also with that of the normal side. When the full range of motion was achieved, joint laxity was lower than that observed immediately after the operation (P < 0.01), but still remained higher than that of the normal side (P < 0.01). In other words, stability was achieved, but joint laxity was diminished through the operation. In this series, a stiffer artificial ligament than the natural ACL was used, and maximum tension was applied during the operation, aiming at better stability, but this may cause diminution of joint laxity. Received for publication on Sept. 1998; accepted on Dec. 2, 1998     

Interleukin-1 beta influences on lysyl oxidases and matrix metalloproteinases profile of injured anterior cruciate ligament and medial collateral ligament fibroblasts

Purpose

The anterior cruciate ligament (ACL) is known to have a poor healing ability, especially in comparison with the medial collateral ligament (MCL) which can heal relatively well. Interleukin-1beta (IL-1β) is considered to be an important chemical mediator in the acute inflammatory phase of ligament injury. The role of IL-1β-induced expressions of lysyl oxidases (LOXs) and matrix metalloproteinases (MMPs), which respectively facilitate extracellular matrix (ECM) repair and degradation, is poorly understood. In this study, we aim to determine the intrinsic differences between ACL and MCL by characterising the differential expressions of LOXs and MMPs in response to IL-1β in the injury process.

Methods

Semi-quantitative polymerase chain reaction (PCR), quantitative real-time PCR, Western blot, and zymography were performed.

Results

We detected high expressions of IL-1β-induced LOXs in normal ACL and MCL. Then, we found IL-1β induced injured MCL to express more LOXs than injured ACL (up to 2.85-fold in LOX, 2.58-fold in LOXL-1, 1.89-fold in LOXL-2, 2.46-fold in LOXL-3 and 2.18-fold in LOXL-4). Meanwhile, we found IL-1β induced injured ACL to express more MMPs than injured MCL (up to 1.72-fold in MMP-1, 1.95-fold in MMP-2, 2.05-fold in MMP-3 and 2.3-fold in MMP-12). The further protein results coincided with gene expressions above.

Conclusions

Lower expressions of LOXs and higher expressions of MMPs might help to explain the poor healing ability of ACL.     

前交叉韧带损伤对膝关节侧副韧带影响的运动还原在体稳定性研究

目的 对前交叉韧带(ACL)损伤膝关节侧副韧带长度变化进行运动还原在体稳定性研究.方法 2008年1月至6月收治8例单侧膝关节ACL断裂而对侧膝关节止常的患者,男6例,女2例;平均年龄25.3岁;在生理负重膝关节屈曲0°、15°、30°、60°和90°时采集相互垂直的二维(2D)图像,与三维CT(3D)图像在虚拟X线投射系统进行2D/3D图像配准,还原膝关节不同角度时股骨和胫骨的相对三维位置关系,并通过韧带止点还原的方法对内侧副韧带(MCL)、外侧副韧带(LCL)进行韧带长度分析,对比两侧膝关节侧副韧带的长度差异.结果 ACL损伤后在0°、15°和30°患膝MCL长度分别为(40.16±1.63)、(39.11±1.77)、(37.86±1.84)mm,健膝分别为(38.17±1.40)、(37.63±1.37)、(36.60±1.86)mm,健、患膝比较差异均有统计学意义(P<0.05);ACL损伤后在0°、15°和30°患膝LCL长度分别为(50.23±1.18)、(50.30±1.68)、(49.26±1.67)mm,健膝分别为(52.56±1.64)、(52.30±1.48)、(51.83±1.77)mm,健、患膝比较差异均有统计学意义(P<0.05).ACL损伤后60°和90°健、患膝MCL、LCL长度差异均无统计学意义(P>0.05).结论 通过2D/3D图像配准技术可以实现膝火节的运动还原并获得ACL损伤后生理屈曲过程中MCL和LCL的长度变化规律.在0°、15°和30°,ACL损伤后患膝MCL长度较健膝增加,而LCL长度较健膝缩短.