Accessory lateral discoid meniscus

The lateral meniscus tends to have more developmental variation than the medial counterpart. This is a report of an accessory discoid layer of lateral meniscus. All arthroscopic, magnetic resonance imaging and histopathological views are presented.No financial support received from anybody or any commercial party.     

Roentgen anatomy of the posterior horn of the lateral meniscus.

The roentgen anatomy of the posterior horn of the lateral meniscus of the knee is presented with particular attention to the relationships between the popliteus tendon, joint capsule and meniscus. The popliteus tendon creates a tunnel as it passes obliquely through the posterior half of the meniscus creating two walls (medial and lateral) and a roof (superior attachment) and a floor (inferior attachment). The boundaries are readily visible on the double-contrast knee arthrogram. Familiarity with these relationships aids in the diagnosis of meniscal injuries.     

MRI of discoid lateral meniscus]

We retrospectively reviewed the MR examinations of 10 patients (17 knees) with surgically documented discoid lateral meniscus of the knee joint. As MRI of the knee is being used more often, the criteria for diagnosis of this entity with MRI need to be established. We tried to define MRI criteria for the detection of discoid menisci by performing numerical measurements of MR images on a display screen. The transverse diameter of the midbody of a discoid lateral meniscus averaged 21.9 mm (normal control: 8.6 mm), and its proportion to the transverse width of the tibia averaged 29.4% (normal control: 12.0%). The measurable difference in height between the discoid and the medial meniscus was negligible. The number of sagittal sections on which the anterior and posterior horns connected varied from two to five in cases of discoid lateral meniscus, and from zero to two in normal controls. Among these parameters, the transverse diameter and its proportion of the transverse width of the tibia proved to be the most reliable. We concluded that a discoid meniscus is indicated if a transverse diameter of a lateral meniscus exceeds 15 mm (proportion to the tibia: 20%).     

Locking knee caused by subluxation of the posterior horn of the lateral meniscus

The authors report a case of repetitive locking knee caused by a subluxation of the posterior horn of a normal lateral meniscus. The posterior horn was sutured to the posterior knee capsule and the athlete resumed complete sports activity 4 months after the surgery.     

Symptomatic torn discoid lateral meniscus in adults

The purposes of this study were to report degenerative changes that coexist with a symptomatic torn discoid lateral meniscus in adults and to analyze the factors associated with the accompanied degenerative changes. From 1997 to 2008, 329 knees in the 305 patients were included. Associations between the status of the meniscus and the coexisting degenerative changes on the images and the arthroscopic findings were statistically analyzed. Marginal osteophyte was seen on conventional radiography in 118 patients (36%). Ninety patients (27%) had arthroscopically confirmed chondral lesion. Age, duration of symptoms, the type of meniscus, the type of tear and the magnetic resonance image classification were associated with the formation of the marginal osteophyte and chondral lesion on univariate analysis (P < 0.05). After conducting multivariate analysis, the type of tear and magnetic resonance image classification had a statistically significant association with the severity of marginal osteophyte and chondral lesion (P < 0.05).     

MRI appearance of Wrisberg variant of discoid lateral meniscus

OBJECTIVE: A discoid lateral meniscus is a common normal variant, occurring in approximately 3-5% of the population. A subgroup of the discoid lateral meniscus known as the Wrisberg variant occurs when there is no posterior attachment of the lateral meniscus. Instead, Wrisberg's ligament becomes the only lateral meniscus posterior stabilizer, with a symptomatic hypermobile meniscus. Although it is commonly described in the orthopedics literature, to our knowledge the Wrisberg variant of the discoid lateral meniscus is not mentioned in the radiology literature. This article describes the MRI appearance of this important yet often unrecognized process. CONCLUSION: The Wrisberg variant of the discoid lateral meniscus is a rare condition with a highly suggestive clinical history. The musculoskeletal radiologist should consider this diagnosis whenever a discoid lateral meniscus is identified because making this elusive diagnosis may prove immensely useful for the orthopedic surgeon.     

MR imaging of meniscal tears with discoid lateral meniscus

Objective: To study MR findings of meniscal tears with discoid lateral menisci (DLMs) and to evaluate the incidence and accuracy of MRI compared to arthroscopical surgery. Material and methods: MR appearances of surgically proved torn discoid lateral menisci (DLM) were studied in 57 knees (40 patients). They were all performed with a 1.5T MR before surgery. MR sequences included T1- and T2* weighted images on both coronal and sagittal planes and 3D-axial images with a slice thickness of 0.7 mm. Result: Of 57 DLMs, there were 32 complete DLMs and 25 incomplete DLMs. Twenty-five of 32 complete DLMs had tears; including seven with intrasubstance tear, five with radial tear, five with other kinds of tears and eight with severe tears involving whole meniscus. On the other hand, 13 of 25 incomplete DLMs had tears; including two with intrasubstance tear, six with radial tear, four with other kinds of tears and one with severe tears. All DLMs were correctly diagnosed on MR images. Twenty-seven of 38 tears with DLM were correctly identified on conventional 2D MR images. This yielded 71.1% sensitivity, 100% specificity and 80.7% overall accuracy. When adding axial 3D MR images to 2D MR images, 36 of 38 tears were correctly diagnosed. A combination of both techniques yielded a sensitivity of 94.7% and a specificity of 100%. Ten of 11 radial tears with DLM were correctly identified on 3D axial images, where only three of them could be diagnosed on conventional 2D images. Eight of nine intrasubstance tears were correctly identified on 3D axial images, where six of them could be diagnosed on conventional 2D images. Conclusion: DLMs had a much higher incidence of meniscal tears than normally shaped lateral menisci and MR is the only modality of choice to evaluate them before surgery. Especially 3D axial MR images were quite useful in the detection of intrasubstance and radial tears often associated with DLMs.     

Arthroscopic treatment for symptomatic discoid lateral meniscus during childhood

Purpose  

The purpose of this study was to review the operative long-term results of a large cohort of children treated arthroscopically for a symptomatic discoid lateral meniscus.     

Arthroscopic reduction and internal fixation of an avulsion fracture of the posterior horn of the lateral meniscus

We report a very rare case of an avulsion fracture of the posterior horn of the lateral meniscus associated with ACL tear, which was successfully treated by arthroscopic reduction and pullout fixation of the fragment along with ACL reconstruction.     

Arthroscopic partial meniscectomy for horizontal tear of discoid lateral meniscus

A new method of arthroscopic partial meniscectomy for horizontal tear of discoid lateral meniscus was devised to preserve as much meniscal tissue as possible. To evaluate the clinical result of this method for horizontal tear of discoid lateral meniscus, 31 knees (30 patients) were reviewed at an average follow-up of 35 months (range 14-48 months). Horizontally torn discoid lateral menisci were classified as incomplete (11 cases) or complete (20 cases) by the Watanabe classification; no Wrisberg type was noted. Partial meniscectomy was performed in all cases. For the technique of a new method of partial meniscectomy, the unstable leaf of the horizontally torn meniscus was removed to the peripheral rim, but the stable one was preserved and reshaped to produce the similar appearance to the normal lateral meniscus in terms of width and thickness. It was trimmed to have a balanced rim of meniscal tissue about 6-8 mm in width. Meniscal repair was added to partial meniscectomy in one case. All the cases were rated using the Lysholm Knee Scoring Scale and were reviewed to recognize retear clinically. The scores increased after partial meniscectomy by average 20.7 (from 73.0 to 93.7). Recurrence of tear or aggravation of symptoms was not noted at the final follow-up.     

Bilateral complete discoid medial meniscus combined with posterior cyst formation

Bilateral discoid medial menisci is an extremely rare condition of the knee and it can be associated to other pathological findings, including anterior portion cyst formation. We report on the clinical features, radiographic findings, treatment and results of one patient who presented a bilateral medial discoid meniscus combined with posterior portion cyst of the left knee. To the best of the author’s knowledge, this is the first case of bilateral medial discoid meniscus associated with posterior portion cyst formation.     

膝关节外侧盘状半月板损伤与软骨损伤的相关性研究

目的探究单膝外侧盘状半月板(discoid lateral meniscus,DLM)损伤与膝关节软骨损伤的关系并分析合并单膝DLM的膝关节软骨损伤的危险因素。方法 2011年1月~2014年1月,根据纳入与排除标准笔者共收治于MRI下诊断为单膝DLM患者166例,女性103例,男性63例;年龄7~48岁,平均38岁。记录患者盘状半月板变性撕裂情况,并根据半月板损伤情况分为完整组(10例)、变性组(122例)和撕裂组(34例),利用全器官MRI评分(whole-organ magnetic resonance imaging score,WORMS)法对膝关节软骨损伤情况进行评分,记录患者性别、年龄、BMI指数,通过单因素方差分析比较三组间一般情况以及膝关节软骨损伤评分的差异。对三组患者进行多因素Logistic回归分析,探讨其膝关节软骨损伤的危险因素。结果完整组、变性组、撕裂组三组平均年龄分别为(39.8±19.5)岁、(37.9±15.5)岁、(36.3±15.6)岁,差异均无统计学意义(P0.05);BMI指数分别为23.3、23.7、24.8,差异均无统计学意义(P0.05)。膝关节软骨总体评分在三组间不全相等(P0.01),根据最小显著差异法(least significant difference,LSD)进行两两比较,撕裂组总评分高于变性组(P0.01),变性组高于完整组(P=0.005)。所有患者经多因素Logistic回归分析,性别(P=0.020;OR 1.097[0.132~3.841])、BMI指数(P0.01;OR 16.048[6.042~42.628])及DLM损伤(P=0.011;OR 6.137[1.516~24.800])均是软骨损伤的独立危险因素。结论在伴有单膝DLM的患者中,女性、BMI24kg/m2及DLM损伤为膝关节软骨损伤的独立危险因素,且DLM损伤程度越高,膝关节软骨损伤程度也越高。     

Effects of arthroscopic meniscectomy on the long-term prognosis for the discoid lateral meniscus

This study compared the long-term clinical and radiological outcomes, according to the extent of arthroscopic meniscectomy, of complete and incomplete types of the discoid lateral meniscus. A total of 125 discoid menisci (74 complete and 51 incomplete types) without significant cartilage erosion at the time of surgery were included. The extent of meniscectomy was decided along with tear patterns and the stability of the discoid meniscus. Both clinical and radiological results were evaluated after total or partial meniscectomy. In the complete type of discoid meniscus with less than 5 years of follow-up, the total meniscectomy group showed better clinical results than the partial meniscectomy group. However, with over 5 years of follow-up, there were no differences between the two groups. In the radiological results, there was no significant difference between the two groups during the first 5 years after operation. However, with more than 5 years of follow-up, the partial meniscectomy group showed better results than the total meniscectomy group. In the incomplete-type discoid meniscus, clinical results were better in the partial meniscectomy group regardless of the follow-up periods. In the radiological results, the partial meniscectomy group showed better results for only more than 5 years of follow-up. The long-term prognosis after arthroscopic meniscectomy for the torn discoid lateral meniscus was related to the volume of the meniscus removed.     

膝板股韧带附着区外侧半月板后角撕裂的MRI表现及诊断价值

目的 探讨膝板股韧带附着区外侧半月板后角（PHLM）撕裂的MRI表现及鉴别诊断价值。 方法 选取2012年12月至2018年6月因前交叉韧带（ACL）损伤在南通市通州区中医院就诊的35例膝板股韧带附着区PHLM撕裂患者作为观察组,搜集同期30例ACL损伤但非PHLM撕裂患者作为对照A组,另选取同期例行体检的30名健康者作为对照B组。3组受试者均行膝关节MRI检查,观察3组受试者的MRI表现。分别应用χ 2检验、单因素方差分析和t检验分析膝关节MRI征象的发生率、膝关节周围结构的损伤情况及膝关节线状高信号影显示的层数和长度,并采用受试者工作特征（ROC）曲线分析鉴别诊断PHLM真、假性撕裂的效能。 结果 观察组患者在MRI矢状面和横断面图像上均表现为明显的PHLM周缘部线状高信号,矢状面上可连续检出（5.75±1.38）层（称“连续线征”）,横断面上自内向外延伸（15.06±5.02）mm（称“拉链征”）,与对照A组、B组比较差异均有统计学意义（F=43.231、36.113,均P<0.05）。以“连续线征”和“拉链征”作为阳性标准,MRI诊断膝板股韧带附着区PHLM撕裂的灵敏度为85.71%、特异度为95.00%、准确率为91.58%。 结论 膝板股韧带附着区PHLM撕裂在MRI上有明显的征象,辅以“连续线征”和“拉链征”进行鉴别诊断,可明显提升诊断效果。     

The posterior horn of the lateral meniscus is a reliable novel landmark for femoral tunnel placement in ACL reconstruction

Purpose

Femoral tunnel placement is essential for good outcome in anterior cruciate ligament (ACL) reconstruction. In the past, several attempts have been made to optimize femoral tunnel placement. It was observed that the posterior horn of the lateral meniscus was always located directly below to the desired femoral ACL tunnel position, when the knee was brought to deep flexion (>?120°). The goal of the present study was to verify the hypothesis that the posterior horn of the lateral meniscus can be used as a landmark for femoral tunnel placement.

Methods

Out of a consecutive series of ACL reconstructions done by a single surgeon, 55 lateral radiographs were evaluated according to the quadrant method by Bernard and Hertel. Additionally, on anterior-posterior radiographs the femoral tunnel angle was determined.

Results

In the present case series the posterior horn of the lateral meniscus could be identified and used as a landmark for femoral tunnel placement in all cases. The mean tunnel depth was 24?±?5.1% and the mean tunnel height was 31.3?±?5.7%. The mean femoral tunnel angle was 41?±?4.9° using the anatomical axis as a reference. Compared to previous cadaver studies the data of the present study were within their anatomical range of the native ACL insertion site.

Conclusion

The suggested technique using the posterior horn of the lateral meniscus as a landmark for femoral tunnel placement showed reproducible results and matches the native ACL insertion site compared to previous cadaveric studies. In particular, non-experienced ACL surgeons will benefit from this apparent landmark and the corresponding easy-to-use ACL reconstruction method.

Level of evidence

IV.

     

A three-dimensional gradient refocussed 3D volume imaging of discoid lateral meniscus

An axial 3D volume scan with MRI was applied to the evaluation of discoid lateral meniscus of the knee. By 0.7 mm-thick thin-sliced and gapless images with volume scan, characteristically elongated appearance of discoid lateral meniscus was clearly depicted. These MR findings completely accorded with those on arthroscopy. Our conclusion is that an axial 3D volume scan was essential to the diagnosis of discoid lateral meniscus.     

Radial tears in the root of the posterior horn of the medial meniscus

The purpose of this study is to define the clinical features and characteristics of radial tears in the root of the posterior horn of the medial meniscus and to report the outcome of arthroscopic treatment. Arthroscopic meniscus surgery was performed on 7,148 knees. Of those, 722 (10.1%) were radial tear in the root of the posterior horn of the medial meniscus. We reviewed the medical records from a random sample of 67 subjects studied (mean age 55.8 years, range 38-72, mean follow-up period 56.7 months, range, 8-123), which included surgical notes and detailed arthroscopic photographs of 70 knees. All patients were treated with arthroscopic partial meniscectomy. The age distribution, preoperative physical signs, results of magnetic resonance imaging , body mass index, and surgical findings of the study subjects were analyzed and the clinical results were graded with the Lysholm knee scoring scale and a questionnaire. Radiologic evaluation consisted of preoperative and at the latest follow-up radiographs. Eighty percent of the patients were older than 50 years, and 80.6% were either obese or morbidly obese. The mean Lysholm score improved from a preoperative value of 53 to a value of 67. The average preoperative Kellgren-Lawrence radiograph grade was 2 (range 0-3 points), a value that increased to 3 (range 2-4) at the latest follow-up, which showed a significant worsening. The preoperative MRI was reevaluated after the arthroscopic confirmation of a medial meniscal root tear. A tear could be demonstrated in only 72.9% of the patients, the rest of whom demonstrated degeneration and/or fluid accumulation at the posterior horn without a visible meniscal tear. Radial tears in the root of the medial meniscal posterior horn, which may not be visible in about one-third of the preoperative MRI scans, are common. That type of meniscal tear is strongly associated with obesity and older age and is morphologically different from the degenerative tears that often occur in the posterior horn. Partial meniscectomy provides symptomatic relief in most cases but does not arrest the progression of radiographically revealed osteoarthritis.     

Quantitative analysis of the difference between an intact complete discoid lateral meniscus and a torn complete discoid meniscus on MR imaging: a feasibility study for a new classification

Objective  

To determine the quantitative difference between an intact complete discoid lateral meniscus (CDLM) and a torn CDLM on MR imaging.     

Clinical,radiologic and arthroscopic assessment and treatment of bilateral discoid lateral meniscus

The purpose of the study is to evaluate clinical, radiologic and arthroscopic features of bilateral discoid lateral meniscus and to assess the outcome of arthroscopic meniscectomy. Among the 177 arthroscopies performed for discoid lateral meniscus between January 1993 and January 2004, 12 were bilateral. The clinical and radiologic evaluation was done from the records. The type of discoid meniscus, the type of tear was assessed arthroscopically. All patients underwent arthroscopic meniscectomy. Patients were followed up for a minimum period of 2 years. All patients had pain as presenting symptom. Eight patients presented with bilateral knee pain and four patients developed pain in the opposite knee after the affected knee was treated. The classically described thud was present in 11 knees. The widening of the joint space was found in 13 knee radiographs; 14 knees had complete type, nine had incomplete type and one had ring type of discoid lateral meniscus on arthroscopic evaluation; 20 knees involving 10 complete types, all incomplete types and ring type of discoid lateral meniscus showed obvious meniscal tears. The remaining four meniscus showed softening of a portion of the meniscus. Underlying intra-substance tear was visualized arthroscopically in the softened areas on saucerisation. All but one discoid menisci underwent arthroscopic partial central meniscectomy. When followed up for an average period of 32.6 months 19 knees showed excellent results and 5 knees good results. Possibility of bilaterality should be suspected in discoid lateral meniscus. Softening of meniscus denotes underlying intra-substance tear. This finding has not been described in the literature so far. Arthroscopic partial meniscectomy gives good results in symptomatic bilateral discoid meniscus. This to our knowledge is the largest series of bilateral discoid lateral menisci.