Biomechanical consequences of a posterior root tear of the lateral meniscus: stabilizing effect of the meniscofemoral ligament

Purpose

The purpose of this study was to evaluate the effects of different types of lateral meniscus root tears in terms of tibiofemoral contact stress.

Methods

Ten porcine knees each underwent five different testing conditions with the menisci intact, a simulated lateral posterior root tear with and without cutting the meniscofemoral ligament and with an artificial tear of the posterior root of the medial meniscus. Biomechanical testing was performed at 30° of flexion with an axial load of 100 N. A pressure sensor (st Sensor Type S2042, Novel, Munich) was used to measure the tibiofemoral contact area and the tibiofemoral contact pressure. Data were analyzed to assess the differences in contact area and tibiofemoral peak contact pressure among the five meniscal conditions.

Results

There was no significant difference in mean contact pressure between the state with the menisci intact and an isolated posterior root tear of the lateral meniscus. In case of a root tear and a tear of the meniscofemoral ligament, the contact area decreased in comparison with the intact state of the menisci. After additional cutting of the meniscofemoral ligament, the tibiofemoral contact pressure was significantly higher in comparison with the intact state and the avulsion injury. In the medial compartment, joint compression forces were significantly increased in comparison with the intact state after cutting the posterior root of the medial meniscus (P < 0.05).

Conclusions

The consequence of a medial meniscus root tear is well known and was verified by this analysis. The results of the present study show that the biomechanical consequences of a lateral meniscus root tear depend on the state of the meniscofemoral ligament. An increase in tibiofemoral contact pressure is only to be expected in combined injuries of the meniscus root and the meniscofemoral ligaments.

Clinical relevance

Posterior lateral meniscus root tear might have a better prognosis in terms of the development of osteoarthritis when the meniscofemoral ligament is intact.     

膝关节内外侧半月板后根部撕裂的MRI诊断价值

目的:探讨MRI对膝关节内外侧半月板后根部撕裂的诊断价值。方法:回顾性分析2012年1月至2016年1月,关节镜下证实为半月板后根部撕裂的患者43例。其中男25例,女18例;年龄27~69(42.5±8.3)岁;右侧27例,左侧16例。由2名医师采用双盲法独立回顾性分析经关节镜证实的43例半月板后根部撕裂患者的MRI表现,计算MRI对半月板后根部撕裂的诊断敏感性、特异性和准确性,并计算膝关节韧带损伤及半月板脱位等伴随情况。结果:143例中,关节镜手术证实43例半月板后根部撕裂,包括内侧撕裂24例,外侧撕裂19例。医师A诊断内侧半月板后根部撕裂的敏感性、特异性、准确性分别为91.67%、86.6%、83.9%,伴内侧半月板突出19例,伴前交叉韧带撕裂2例;外侧半月板后跟部撕裂的敏感性、特异性、准确性分别为73.7%、79.9%、79%,伴外侧半月板突出4例,伴前交叉韧带撕裂16例。医师B诊断内侧半月板后根部撕裂的敏感性、特异性、准确性分别为87.5%、87.4%、87.4%,伴内侧半月板突出19例,伴前交叉韧带撕裂2例;外侧半月板后跟部撕裂的敏感性、特异性、准确性分别为78.9%、82.3%、82.5%,伴外侧半月板突出4例,伴前交叉韧带撕裂16例。2名医师采用MRI诊断内、外侧半月板后根部撕裂的一致性均好,Kappa值分别为0.81和0.67。结论 :膝关节MRI诊断内外侧半月板后跟部撕裂及其伴随征象具有较大价值,为临床医生术前诊断提供依据,值得临床推广应用。     

Posterior root tear of the medial and lateral meniscus

An avulsion of the tibial insertion of the meniscus or a radial tear close to the meniscal insertion is defined as a root tear. In clinical practice, the incidence of these lesions is often underestimated. However, several biomechanical studies have shown that the effect of a root tear is comparable to a total meniscectomy. Clinical studies documented progredient arthritic changes following root tears, thereby supporting basic science studies. The clinical diagnosis is limited by unspecific symptoms. In addition to the diagnostic arthroscopy, MRI is considered to be the gold standard of diagnosis of a meniscal root tear. Three different direct MRI signs for the diagnosis of a meniscus root tear have been described: Radial linear defect in the axial plane, vertical linear defect (truncation sign) in the coronal plane, and the so-called ghost meniscus sign in the sagittal plane. Meniscal extrusion is also considered to be an indirect sign of a root tear, but is less common in lateral root tears. During arthroscopy, the function of the meniscus root must be assessed by probing. However, visualization of the meniscal insertions is challenging. Refixation of the meniscal root can be performed using a transtibial pull-out suture, suture anchors, or side-to-side repair. Several short-term studies reported good clinical results after medial or lateral root repair. Nevertheless, MRI and second-look arthroscopy revealed high rates of incomplete or absent healing, especially for medial root tears. To date, most studies are case series with short-term follow-up and level IV evidence. Outerbridge grade 3 or 4 chondral lesions and varus malalignment of >5° were found to predict an inferior clinical outcome after medial meniscus root repair. Further research is needed to evaluate long-term results and to define evident criteria for meniscal root repair.     

关节镜下经骨隧道缝合治疗膝关节外侧半月板后根部撕裂

目的:探讨关节镜下经骨隧道缝合治疗膝关节外侧半月板后根部撕裂的临床疗效。方法:自2012年1月至2014年12月,采用关节镜下经骨隧道缝合治疗23例膝关节外侧半月板后根部撕裂患者,其中男15例,女8例;年龄19～48(25.0±4.7)岁;左膝10例,右膝13例。记录患者并发症情况,术前及术后12个月采用Lysholm评分进行临床疗效评价,并采用VAS进行疼痛评价。术后12个月通过MRI检查外侧半月板损伤愈合情况。结果:23例患者获得随访,时间13～24(17.0±4.3)个月。术后无血管神经损伤及切口感染等并发症发生。术后12个月时19例患者膝关节活动度达到正常,4例患者存在膝关节活动受限。术后12个月Lysholm评分88.52±6.48,较术前46.12±7.35明显提高(P0.05)。术后12个月VAS评分0.8±0.7,较术前4.3±1.6明显降低(P0.05)。结论:采用关节镜下经骨隧道缝合治疗膝关节外侧半月板后根部撕裂,可有效缓解疼痛,降低术后并发症,临床疗效显著。     

Symptomatic bucket handle tear of the lateral meniscus after knee arthroplasty

We report on a 67-year-old women who had pain after a knee arthroplasty in the region of the lateral meniscus. The arthroscopy showed the remainder of the posterior horn of the lateral meniscus, which luxated as a bucket handle tear into the joint. The resection led to an immediate relief. This case show the importance of meticulous removal of the entire menisci during bicondylar surface replacement.

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Résumé  Après l’implantation d’une prothèse de genou une femme, agée de 67 ans, souffrait d’une douleur sur la partie laterale de genou, dans la région du menisque. L’arthroscopie montrait une partie du menisque postérieur, qui etait situé entre les deux composants de la prothese. Après la résection du menisque la douleur avait immédiament disparue. Ce cas souligne l’importance d’une résection exacte du menisque entier dans la technique opératoire d’une prothese de genou.

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Accepted: 25 August 1999     

Use of a Caspari suture punch to repair a radial tear of the lateral meniscus

Summary: Radial meniscal injuries in young patients are challenging problems. A technique not previously described in the literature is presented for radial meniscal repair. A Caspari suture punch is used to repair the inner leaf of the radial tear followed by standard inside-out augmentation with zone-specific cannulas and No. 2.0 PDS suture. This technical note describes the technique and its result in a case report.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 2 (February), 2002: pp 206–210     

Effects of radial tears and partial meniscectomy of lateral meniscus on the knee joint mechanics during the stance phase of the gait cycle—A 3D finite element study

The purpose of the current study was to evaluate influences of radial tears and partial meniscectomy of lateral meniscus on the knee joint mechanics during normal walking by using computational modeling. A 3D geometry of a knee joint of a healthy patient was obtained from our previous study, whereas the data of normal walking were taken from the literature. Cartilage tissue was modeled as a fibril reinforced poroviscoelastic material, whereas meniscal tissue was modeled as a transverse isotropic elastic material. The realistic gait cycle data were implemented into the computational model and the effects of radial tears and partial meniscectemy of lateral meniscus on the knee joint mechanics were simulated. Middle, posterior, and anterior radial tears in lateral meniscus increased stresses by 300%, 430%, and 1530%, respectively, at the ends of tears compared to corresponding areas in the model with intact lateral meniscus. Meniscus tears did not alter stresses and strains at the tibial cartilage surface, whereas partial meniscectomy increased contact pressures, stresses, strains and pore pressures in the tibial cartilage by 50%, 44%, 21%, and 43%, respectively. Increased stresses and strains were observed primarily during the first ～50% of the stance phase of the gait cycle. The present study suggests that anterior radial tear causes the highest risk for the development of total meniscal rupture, whereas partial meniscectomy increases the risk for the development of OA in lateral tibial cartilage. Highest risks for meniscus and cartilage failures are suggested to occur during the loading response and mid‐stance of the gait cycle. In the future, the present modeling may be further developed to offer a clinical tool for aid in decision making of clinical interventions for patients with knee joint injuries. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1208–1217, 2013     

膝关节盘状半月板有限元模型的构建及生物力学分析

[目的]通过CT和MRI数据融合构建膝关节盘状半月板有限元模型,并进行有限元分析和验证,为盘状半月板研究提供可靠的有限元模型。[方法]采集包含盘状半月板膝关节CT和MRI影像数据,导入到Mimics软件中,构建膝关节骨骼、半月板等结构的三维模型。以外部标记为参照点进行模型配准,融合成膝关节整体模型。在Ansys软件中进行网格划分,构建膝关节有限元模型。通过解剖观察和测量对有限元模型进行解剖真实度评估,对其设置材料属性、建立边界条件和施加载荷,进行有限元分析,并验证。[结果]在600 N轴向压力下,股骨与胫骨软骨面发生接触,半月板传导轴向载荷。外侧盘状半月板上表面挤压应力峰值为2.21 MPa,出现在体部的中央;内侧半月板上表面挤压应力分布于前角、体部、后角的游离缘,峰值为6.61 MPa,出现后角游离缘。股骨软骨的挤压应力峰值出现在外侧髁,为0.67 MPa;股骨内侧髁挤压应力峰值为0.52 MPa。胫骨软骨的挤压应力峰值出现在内侧平台,为1.39 MPa,胫骨外侧平台挤压应力峰值为0.62MPa。[结论]通过CT和MRI影像数据融合可以构建符合解剖学特征的膝关节盘状半月板有限元整体模型,能为研究盘状半月板生物力学行为提供可靠、有效的有限元模型。     

内侧半月板后角放射状撕裂与水平撕裂的危险因素分析

 目的 比较内侧半月板后角放射状撕裂和水平撕裂的危险因素。方法 回顾性分析2011年1月至2012年12月收治的390例应用关节镜治疗的内侧半月板撕裂患者的临床资料,选取其中94例内侧半月板后角放射状撕裂患者及95例内侧半月板后角水平撕裂患者作为研究对象。记录并比较内侧半月板后角放射状撕裂与内侧半月板后角水平撕裂两组患者的年龄、性别、症状持续时间、体重指数、外伤史、胫骨后倾角、膝关节外翻角及Outerbridge软骨分级。采用多因素非条件Logistic回归分析半月板放射状撕裂的危险因素。结果 半月板后角水平撕裂和放射撕裂患者的性别（χ²=9.059,P=0.003）、体重指数（t=-2.549,P=0.012）、膝关节外翻角（t=-5.609,P=0.000）及软骨分级（χ²=42.300,P=0.000）的差异有统计学意义,而外伤史（χ²=0.368,P=0.544）、胫骨后倾角（χ²=1.021,P=0.312）、年龄（t=-1.228,P=0.221）及症状持续时间（t=0.272,P=0.786）的差异无统计学意义。多因素分析结果显示外翻角（Or=12.581,P=0.001）、年龄（Or=0.875,P=0.026）及Outerbridge软骨分级Ⅰ~Ⅳ级（Or=33.790、15.558、39.891、91.041,P=0.000）为半月板放射状撕裂的危险因素。结论 半月板后角撕裂在老年骨关节炎患者中的发生率较高,内侧半月板后角放射状撕裂与水平撕裂比较,更容易发生在膝关节内翻、软骨退变严重的老年患者中。     

Complete tear of the lateral meniscus posterior root is associated with meniscal extrusion in anterior cruciate ligament deficient knees

This study aimed to evaluate the relationship between preoperative lateral meniscal extrusion (LME) and arthroscopic findings of lateral meniscus posterior root tear (LMPRT) in knees with anterior cruciate ligament (ACL) tear. Thirty‐five knees that had LMPRTs with concomitant ACL tears on arthroscopy were evaluated. Patients were divided into two groups, partial and complete root tears, via arthroscopic findings at the time of ACL reconstruction. For comparison, we added two groups, using the same database; 20 normal knees (normal group) and 20 ACL‐injured knees without LM injury (intact LM group). We retrospectively measured preoperative LMEs using magnetic resonance imaging (MRI). Twenty‐three knees had partial LMPRTs. Complete LMPRTs were observed in 12 knees. The average LME was ?0.1 ± 0.4 mm in the normal group, 0.2 ± 0.5 mm in the intact LM group, 0.4 ± 0.8 mm in the partial LMPRT group, and 2.0 ± 0.6 mm in the complete LMPRT group. A significant difference in preoperative LMEs was observed between the complete LMPRT group and the other groups (p < 0.001). The receiver operating curve analysis, which distinguishes a partial tear from a complete tear, identified an optimal cut‐off point of 1.1 mm for preoperative LME. This LME cut‐off had a sensitivity of 100% and specificity of 83% for complete LMPRT. We found that preoperative LMEs were larger in complete LMPRTs associated with ACL injuries than in partial LMPRTs. Our results suggest that preoperative MRI‐detected LME may be a useful indicator for estimating LMPRT severity in ACL‐injured knees. Level of evidence: Retrospective comparative study level IV. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1894–1900, 2018.

     

外侧半月板撕裂关节镜术中保留不同半月板层厚膝关节功能及骨性关节炎发生的影响

目的 探讨外侧半月板撕裂关节镜术中保留不同半月板层厚对膝关节功能及骨性关节炎发生的影响.方法 回顾性分析自2013-03-2015-01采用关节镜治疗的50例膝关节外侧半月板撕裂,19例未保留半月板层厚(未保留组),16例部分保留半月板层厚(部分保留组),15例完全保留半月板层厚(完全保留组).比较3组末次随访时膝关节功能Lysholm评分、疼痛VAS评分、Kellgren-Lawrence影像学分级.结果 50例均获得平均22.7(17～32)个月随访.末次随访时,3组Lysholm评分差异有统计学意义(P＜0.05),进一步两两比较,部分保留组、完全保留组Lysholm评分明显高于未保留组,而部分保留组与完全保留组Lysholm评分差异无统计学意义(P＞0.05).3组疼痛VAS评分、Kellgren-Lawrence影像学分级差异无统计学意义(P＞0.05).结论 外侧半月板撕裂关节镜术中保留不同半月板层厚者术后早期膝关节功能恢复更好,并且保留不同层厚半月板对早期膝关节骨性关节炎发生无明显影响.     

Snapping knee caused by a popliteomeniscal fascicle tear of the lateral meniscus in a professional Taekwondo athlete

A 19-year-old male professional Taekwondo athlete presented with a 2-year history of pain-free snapping of his right knee. He reported that his right knee joint gave way during games and training and that he could induce pain-free snapping between the proximal-to-fibular head and the lateral knee joint line. None of these physical findings suggested a meniscal pathology or ligamentous instability. Routine radiographs were normal. Magnetic resonance imaging of his right knee joint showed that the shape of the lateral meniscus was normal, and no lateral meniscus tears existed. On arthroscopic examination, popliteal hiatus view showed a posterosuperior popliteomeniscal fascicle tear between the posterior horn of the lateral meniscus and the posterior joint capsule just posteromedial to the popliteus tendon. With medial traction by probing, this popliteomeniscal tear made visible the significant subluxation of the posterior horn of the lateral meniscus to the center or anterior half of the tibial plateau. Based on the diagnosis of a posterosuperior popliteomeniscal tear of the right knee, Fast-Fix (Smith & Nephew, Andover, Massachusetts) was used for the direct repair of the peripheral portion of the lateral meniscus and joint capsule, targeting the popliteomeniscal junction. At 24 months postoperatively, the patient was performing athletic exercises relevant to his profession and was taking part in Taekwondo games, with no pain or recurrence of snapping. To the authors' knowledge, this is the first report of snapping of the lateral aspect of the knee due to a popliteomeniscal fascicle tear.     

A giraffe neck sign of the medial meniscus: A characteristic finding of the medial meniscus posterior root tear on magnetic resonance imaging

Background

The posterior root ligament of the medial meniscus (MM) has a critical role in regulating the MM movement. An accurate diagnosis of the MM posterior root tear (MMPRT) using magnetic resonance imaging (MRI) is important for preventing sequential osteoarthritis following the MMPRT. However, diagnosis of the MMPRT is relatively difficult even after using several characteristic MRI findings. The aim of this study was to identify a useful meniscal body sign of the MMPRT for improving diagnostic MRI reading.

Tibiofemoral contact mechanics following a horizontal cleavage lesion in the posterior horn of the medial meniscus

The purpose of this study was to determine if a horizontal cleavage lesion (HCL) of the posterior horn of the medial meniscus would result in changes to tibiofemoral contact mechanics, as measured by peak contact pressure and contact area, which can lead to cartilage degeneration. To study this, 10 cadaveric knees were tested in a rig where forces were applied (500 N Compression, 100 N shear, 2.5 Nm Torque) and the knee dynamically flexed from ?5° to 135°, as peak contact pressure and contact area were recorded. After testing of the intact knee, a horizontal cleavage lesion was created arthroscopically and testing repeated. The Wilcoxon signed‐rank test was used to determine if there were differences in peak contact pressure and contact area between the intact knee and that with the HCL. A statistically significant increase in peak contact pressure of 13%, on average, and a decrease in contact area of 6%, on average, was noted following the HCL. This suggests that a horizontal cleavage lesion will result in small but statistically significant changes in tibiofemoral contact mechanics which may lead to cartilage degeneration. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:584–590, 2015.

     

Simultaneous avulsion fracture of the posterior medial and posterior lateral meniscus root: a case report and review of the literature

Injuries of the meniscus roots are increasingly recognized as a serious knee joint pathology. An avulsion fracture of the meniscus root is a rare variant of this injury pattern. In this article, a case of a traumatic simultaneous avulsion fracture of both the posterior medial and posterior lateral meniscus root associated with a tear of the anterior cruciate ligament is presented. Both avulsion fractures were treated by indirect arthroscopic transtibial pullout fixation of the bony fragment. Based on the findings of our literature review, root avulsion fractures seem to be more common in young male patients after an acute trauma to the knee joint.     

内外侧半月板后根部损伤有限元力学研究

[目的]探讨内外侧半月板后根部损伤对膝关节生物力学的影响。[方法]膝关节正常志愿者4例作为研究对象,采用MRI对左膝关节进行扫描,建立膝关节各部位有限元模型,在股骨部分垂直加1 150 N垂直力模拟人体正常周期中的伸直状态,测量应力分布。在完整膝关节有限元模型中同时删除内、外侧半月板根部相应单元和节点,模拟内外测半月板根部同时损伤模型;将完整膝关节模型设为对照组;分别加载1 000 N轴向压缩载荷和134 N向前剪切力,测量不同部位的最大压应力和最大剪切应力。[结果]人体正常走平路膝伸直状态时,承受应力的大小依次为:外侧半月板前部>内侧胫骨平台>股骨外侧髁>内侧半月板后部>股骨内侧髁>外侧胫骨平台>双股骨髁后部。损伤组股骨内髁、股骨外髁、内侧胫骨平台、外侧胫骨平台软骨、外侧半月板最大压应力显著高于完整组(P<0.05)。损伤组股骨内髁、股骨外髁、内侧胫骨平台、外侧胫骨平台软骨、外侧半月板最大剪切力显著高于完整组(P<0.05)。[结论]内、外侧半月板后根部同时损伤导致膝关节各部位承载应力显著增加。