Subject-specific finite element analysis of the human medial collateral ligament during valgus knee loading.

The objectives of this study were (1) to develop subject-specific experimental and finite element (FE) techniques to study the three-dimensional stress-strain behavior of ligaments, with application to the human medial collateral ligament (MCL), and (2) to determine the importance of subject-specific material properties and initial (in situ) strain distribution for prediction of the strain distribution in the MCL under valgus loading. Eight male knees were subjected to varus-valgus loading at flexion angles of 0 degrees, 30 degrees, and 60 degrees. Three-dimensional joint kinematics and MCL strains were recorded during kinematic testing. Following testing, the MCL of each knee was removed to allow measurement of the in situ strain distribution and to perform material testing. A FE model of the femur-MCL-tibia complex was constructed for each knee to simulate valgus loading at each flexion angle, using subject-specific bone and ligament geometry, material properties, and joint kinematics. A transversely isotropic hyperelastic material model was used to represent the MCL. The MCL in situ strain distribution at full extension was used to apply in situ strain to each MCL FE model. FE predicted MCL strains during valgus loading were compared to experimental measurements using regression analysis. The subject-specific FE predictions of strain correlated reasonably well with experimentally measured MCL strains (R(2)=0.83, 0.72, and 0.66 at 0 degrees, 30 degrees, and 60 degrees, respectively). Despite large inter-subject variation in MCL material properties, MCL strain distributions predicted by individual FE models that used average MCL material properties were strongly correlated with subject-specific FE strain predictions (R(2)=0.99 at all flexion angles). However, predictions by FE models that used average in situ strain distributions yielded relatively poor correlations with subject-specific FE predictions (R(2)=0.44, 0.35, and 0.33 at flexion angles of 0 degrees, 30 degrees, and 60 degrees, respectively). The strain distribution within the MCL was nonuniform and changed with flexion angle. The highest MCL strains occurred at full extension in the posterior region of the MCL proximal to the joint line during valgus loading, suggesting this region may be most vulnerable to injury under these loading conditions. This work demonstrates that subject-specific FE models can predict the complex, nonuniform strain fields that occur in ligaments due to external loading of the joint.     

Deep medial collateral ligament tear during knee arthroscopy

We report herein deep medial collateral ligament (MCL) tear of the knee with application of valgus stress during arthroscopic partial medial meniscectomy. With symptomatic treatment only, the patient went on to heal this injury without incident and recovered in an expected fashion from arthroscopic surgery. There is no earlier report in the literature of deep MCL tear during knee arthroscopy. Awareness of this entity, its consequences, and optimal management are essential as arthroscopic partial meniscectomy is the most common surgery performed by orthopedic surgeons.     

Single-strand ligament reconstruction of the medial collateral ligament restores valgus elbow stability

The purpose of this study was to determine the contribution of the central portion of the anterior bundle of the medial collateral ligament (MCL) to elbow stability and to evaluate the effectiveness of a single-strand MCL reconstruction in restoring elbow stability. Testing of 11 fresh-frozen upper extremities was first performed on the intact elbow and then with the capsule, flexor-pronator muscle group, posterior bundle, anterior or posterior band, and central band cut sequentially. Next, a single-strand reconstruction of the MCL was performed. The elbow was moved passively through a full arc of flexion in both varus and valgus gravity-loaded positions. Ulnar movement with respect to the humerus was analyzed by means of an electromagnetic tracking system. Maximum varus-valgus laxity throughout the arc of supinated flexion and pronated flexion was 6.6 degree plus minus 2.4 degree and 7.4 degree plus minus 2.0 degree, respectively, for the intact specimen, 34.2 degree plus minus 5.6 degree and 37.7 degree plus minus 11.8 degree for the specimen with all of the medial valgus elbow stabilizers cut, and 9.0 degree plus minus 2.5 degree and 10.5 degree plus minus 2.7 degree for the reconstructed specimen. Maximum varus-valgus laxity was not significantly different among any of the sectioning sequences until the central band was cut (P <.0001). There was no significant difference in maximum varus-valgus laxity between the intact and reconstructed elbows (P <.05). Our results demonstrate that the central band is an important valgus stabilizer of the elbow and that a simplified single-strand reconstruction is able to restore stability to the MCL-deficient elbow.     

Repair of medial collateral ligament injury during total knee arthoplasty

Intraoperative midsubstance lacerations of the medial collateral ligament (MCL) must be addressed during surgery, and failure to obtain coronal plane stability could affect patient outcomes and satisfaction. This article reports our results of a series of patients who sustained an intraoperative MCL injury during a primary total knee arthroplasty and were treated by direct primary repair and no change in implant constraint or postoperative protocol. Over a 5-year period, 9 patients sustained this complication. We reviewed their subjective satisfaction and stability, as well as objective measures such as functional scores, physical examinations, and radiographs. Average patient age was 58 years, and mean patient body mass index was 43.3. All patients were satisfied with the procedure and demonstrated no instability on physical examination. Average Knee Society pain score was 91.5 and functional score was 73.3. No radiographic changes or signs of loosening were noted. This novel approach for intraoperative midsubstance lacerations of the MCL does not involve altering implants or postoperative protocols and has encouraging results.     

膝关节置换术中内侧副韧带损伤处理的研究进展

全膝关节置换术中发生内侧副韧带(MCL)损伤比较罕见,但该并发症确是与全膝关节置换(TKA)相关的最严重的并发症之一,且常常被医生忽视。内侧副韧带(MCL)的完整性对于正常的膝关节功能和全膝关节置换术(TKA)术后维持外翻应力的稳定性和软组织平衡至关重要。如果术中没有发现MCL损伤或内侧副韧带受损未进行特殊处理可能会导致聚乙烯衬垫磨损加速和影响假体最终生存率。这表明术中及时识别和采用合适的治疗方法至关重要。本文回顾了TKA术中MCL损伤的特点,高危因素,损伤原因,鉴别方法以及治疗方法等。     

Morphology of the medial collateral ligament of the knee

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.     

跖趾关节内侧副韧带重建术治疗外翻

目的 探讨跖趾关节内侧副韧带重建加跖趾关节成形术治疗外翻疗效.方法 采用改良跖趾关节成形术治疗外翻23例(38足),并对趾畸形的矫正程度、疼痛症状的改善及行走功能的恢复等进行充分评估.结果 本组患者外翻角(HAV)及第一、二跖骨间夹角(IMA)术前、后比较,差异有统计学意义(P<0.05).术后随访(13.6±2.3)个月,疗效优28足,良8足,可1足,差1足,总优良率达94.7%.结论 跖趾关节内侧副韧带重建加跖趾关节成形术能够治疗多种中、重度外翻及合并趾跖关节炎患者,能有效改善足部外形及症状,恢复行走功能,并发症少.     

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     

Technical tip: Reconstruction of medial collateral ligament in correction of hallux valgus deformity with primary medial collateral ligamentous insufficiency

In cases of hallux valgus deformity with primary medial collateral ligamentous insufficiency, there will be an abnormal hallux valgus angle with relatively normal intermetatarsal angle and sesamoid positions. Metatarsal osteotomies may not be effective to correct the deformity. Plication of the attenuated medial capsule may not be strong enough to provide long lasting correction of the hallux valgus deformity. We describe a minimally invasive technique of reconstruction of the medial collateral ligament by means of extensor hallucis brevis tendon graft. This can provide a stronger medial constraint to prevent recurrence of hallux valgus deformity.     

Medial collateral knee ligament healing: Combined medial collateral and anterior cruciate ligament injuries studied in rabbits

We examined the histological appearance and biochemical properties of the healing medial collateral ligament (MCL) of a rabbit knee after combined MCL and anterior cruciate ligament (ACL) injury treated with ACL reconstruction and with or without MCL repair. By so doing, we hoped to understand better our previous biomechanical observations (Ohno et al. 1995) and possibly learn where to focus future investigation into improving the quality of the healing MCL.

Ligaments were examined at 6 and 12 weeks of healing. We found healing of all ligaments with hypercellularity and fibroblast elongation along the axis of loading, as expected. Unexpected, however, was the finding of multiple osteophytes in both the repaired and nonrepaired specimens at the medial borders of the joint and at the MCL insertions. These were felt to affect possibly the biomechanics of the MCL by causing stress risers at the point where they undermine the ligament. Biochemically, we demonstrated a correlation between collagen content and hydroxypyridinium crosslinks and modulus of elasticity. While this implies that the modulus is dependent on collagen content and hydroxypyridinium crosslink density, modulus is also probably dependent on other factors such as collagen organization, type and internal structure. Overall, the detailed characterization and correlation between the histological, biochemical, and biomechanical properties of the healing MCL in the severe knee injury model provide insight into the functional behavior of the healing MCL.     

Anatomical reconstruction of the medial collateral ligament and the posterior oblique ligament of the knee

Chronic medial knee instability is frequently due to a combination of superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL) insufficiency. We present a new technique for simultaneous anatomical reconstruction of sMCL and POL, using an anterior tibialis tendon allograft with three reconstruction tunnels.     

带线锚钉治疗膝关节内侧副韧带止点断裂

膝关节内侧副韧带(medial collateral ligament,MCL)损伤临床上较为常见,其损伤后对关节的制约作用遭到破坏,造成膝关节内侧不稳定或松弛,远期还可继发骨关节炎,导致疼痛与关节功能障碍.依据损伤程度其可分为Ⅰ、Ⅱ、Ⅲ度.其中以ⅢB型韧带止点断裂部损伤治疗较为棘手,我院自2006年6月至2008年7月对20例膝关节MCL带附丽部断裂伤,应用带线锚钉修复重建,疗效满意,现报告如下.     

Stability after medial collateral ligament release in total knee arthroplasty.

Six knees from cadavers were tested for change in stability after release of the medial collateral ligament with posterior cruciate-retaining and substituting total knee replacements. Load deformation curves of the joint were recorded in full extension and 30 degrees, 60 degrees, and 90 degrees flexion under a 10 N-m varus and valgus torque, 1.5 N-m internal and external rotational torque, and a 35 N anterior and posterior force to test stability in each knee. The intact specimen and posterior cruciate ligament-retaining total joint replacement were tested for baseline comparisons. The superficial medial collateral ligament was released, followed by release of the posterior cruciate ligament. The knee then was converted to a posterior-stabilized implant. After medial collateral ligament release, valgus laxity was statistically significantly greater at 30 degrees, 60 degrees, and 90 degrees flexion after posterior cruciate ligament sacrifice than it was when the posterior cruciate ligament was retained. The posterior-stabilizing post added little to varus and valgus stability. Small, but significant, differences were seen in internal and external rotation before and after posterior cruciate ligament sacrifice. The posterior-stabilized total knee arthroplasty was even more rotationally constrained in full extension than the knee with intact medial collateral ligament and posterior cruciate ligament.     

Fastin锚钉植入修复膝内侧副韧带损伤的临床观察

随着户外活动的增加以及快速交通的发展,运动损伤和车祸伤所致的各类膝关节韧带断裂发病率逐年增高,其中膝关节内侧副韧带损伤占膝关节韧带损伤的比例很大。我科对膝内侧副韧带附着点部位韧带撕裂伤进行Fastin锚钉植入修复,创伤小,手术时间短,效果满意,现报告如下。     

Viscoelastic properties of the human medial collateral ligament under longitudinal, transverse and shear loading.

Ligament viscoelasticity controls viscous dissipation of energy and thus the potential for injury or catastrophic failure. Viscoelasticity under different loading conditions is likely related to the organization and anisotropy of the tissue. The objective of this study was to quantify the strain- and frequency-dependent viscoelastic behavior of the human medial collateral ligament (MCL) in tension along its longitudinal and transverse directions, and under shear along the fiber direction. The overall hypothesis was that human MCL would exhibit direction-dependent viscoelastic behavior, reflecting the composite structural organization of the tissue. Incremental stress relaxation testing was performed, followed by the application of small sinusoidal strain oscillations at three different equilibrium strain levels. The peak and equilibrium stress-strain curves for the longitudinal, transverse and shear tests demonstrate that the instantaneous and long-time stress-strain response of the tissue differs significantly between loading conditions of along-fiber stretch, cross-fiber stretch and along-fiber shear. The reduced relaxation curves demonstrated at least two relaxation times for all three test modes. Relaxation resulted in stresses that were 60-80% of the initial stress after 1000 s. Incremental stress relaxation proceeded faster at the lowest strain level for all three test configurations. Dynamic stiffness varied greatly with test mode and equilibrium strain level, and showed a modest but significant increase with frequency of applied strain oscillations for longitudinal and shear tests. Phase angle was unaffected by strain level (with exception of lowest strain level for longitudinal samples) but showed a significant increase with increasing strain oscillation frequency. There was no effect of test type on the phase angle. The increase in phase and thus energy dissipation at higher frequencies may protect the tissue from injury at faster loading rates. Results suggest that the long-time relaxation behavior and the short-time dynamic energy dissipation of ligament may be governed by different viscoelastic mechanisms, yet these mechanisms may affect tissue viscoelasticity similarly under different loading configurations.     

关节镜辅助下治疗膝内侧副韧带损伤

膝关节内侧副韧带损伤是常见的运动性疾病，是膝关节不稳定的重要因素，常导致股部肌肉萎缩和膝关节骨性关节炎，早期正确诊断和治疗非常重要。本科自2001年以来，共收治13例患者，均在关节镜辅助下行韧带修补重建手术，获得良好效果。     

Valgus medial collateral ligament rupture causes concomitant loading and damage of the anterior cruciate ligament

This study tested the hypothesis that application of a valgus force necessary to create a complete medial collateral ligament (MCL) injury causes damage to the anterior cruciate ligament (ACL). Twelve cadaveric knees were used to measure concomitant loading and damage to the ACL in valgus knee loading sufficient to cause a grade III MCL injury. Displacement sensors were placed on the anteromedial bundle of the ACL and posterior oblique ligament to monitor tensile strain during creation of the MCL injury. A valgus moment was applied to knees flexed at 30 degrees, displacing the joint into valgus rotation beyond MCL rupture. Following valgus loading and MCL injury, femur-ACL-tibia specimens were tested to failure to compare ACL mechanical integrity to noninjured control specimens. Average ACL strength in MCL ruptured knees (1250 +/- 90 N) was statistically lower (P < or = .05) than that for control knees (2110 +/- 50 N). Strain measurements exhibited concomitant posterior oblique ligament strain during valgus loading, whereas ACL strain increased substantially only after MCL rupture. These data indicate that the ACL can be compromised in isolated grade III MCL injuries.