The Impact of Posterior Root Tears of the Medial Meniscus on Meniscal Extrusion and Cartilage Degeneration

doi:10.21203/rs.3.rs-4901809/v1

Download PDF

Research Article

The Impact of Posterior Root Tears of the Medial Meniscus on Meniscal Extrusion and Cartilage Degeneration

https://doi.org/10.21203/rs.3.rs-4901809/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

Background: To explore the impact of the severity of the tear gap caused by medial meniscus posterior root (MMPR) tear on medial meniscus extrusion and bone cartilage based on magnetic resonance imaging (MRI).

Methods: A retrospective analysis was conducted on 153 patients with medial meniscus root tear who were admitted to Jinhua Central Hospital from January 1, 2020, to October 31, 2023. According to the size of the tear gap, they were divided into mild displacement (M) group (≤4mm) and extensive displacement (W) group (>4mm). The M group consisted of 73 cases (70 females, 3 males), aged 52-63 years (mean age 56 years); the W group consisted of 80 cases (75 females, 5 males), aged 55-65 years (mean age 57.5 years). There was no significant difference in age and gender between the two groups (P>0.05). The distances of medial meniscus extrusion and bone cartilage injury in the two groups were compared and analyzed.

Results: In the M group, the average extrusion distance of the medial meniscus was 3.5mm (1.5-5mm), and in the W group, the average extrusion distance of the medial meniscus was 4.53mm (2.5-7.3mm). The comparison between the two groups was statistically significant (P<0.05). The degree of femoral medial condyle cartilage degeneration was more severe in the W group, which was statistically significant compared with the M group (P<0.05). In the W group, bone hyperplasia, subchondral cyst formation, and narrowing of the medial compartment were more common, but there was no significant difference compared to the M group (P>0.05).

Conclusion: The size of the tear gap caused by medial meniscus root tear on MRI is an important risk factor for medial meniscus extrusion and bone cartilage degeneration, which can provide a good idea for predicting the progression of osteoarthritis clinically.

meniscus

root

tear

gap

extrusion

bone cartilage

Medial meniscus posterior root tear (MMPR) refers to the radial tear of the medial meniscus posterior root from the tibial attachment site or within 1cm of the posterior root attachment site, accounting for 10%-27.8% of all meniscal tears. Once the root of the meniscus is torn, the hoop effect of the meniscus disappears, losing its function of dispersing stress and stabilizing the joint.[1] After the root tear of the meniscus, it will displace peripherally to form "meniscal extrusion," and a "fissure sign" will appear on the coronal MRI. The tear gap of the medial meniscus root is the distance between the tear point and the inner surface of the displaced meniscus.[2] Theoretically, the severity of the tear gap should be positively correlated with the degree of meniscal extrusion, but there is little research in this area.[1][3] However, Kim et al. found that besides the tear gap, there are many other factors related to meniscal extrusion, such as the severity of osteoarthritis, which is closely related to meniscal extrusion.[1] Therefore, measuring the tear gap to evaluate the functional status of the medial meniscus after root tear is more reliable than evaluating meniscal extrusion. Moreover, there are few reports in the literature on the relationship between meniscal tear gap and cartilage injury.

The purpose of our study is to determine the relationship between the severity of tear gap caused by MMPR and medial meniscal extrusion, cartilage of the medial compartment of the knee joint, and bone lesions.

Case Data

Images of patients who underwent knee joint MRI examinations at our hospital for any reason between January 1, 2020, and October 31, 2023, and were found to have a meniscal root tear were re-evaluated. A total of 153 patients with a complete MMPR tear were included in the study. They were divided into mild displacement (M) group (≤ 4mm) and extensive displacement (W) group (> 4mm) based on the size of the tear gap. M group: 73 cases (70 females, 3 males), aged 52–63 years (mean 56 years); W group: 80 cases (75 females, 5 males), aged 55–65 years (mean 57.5 years). Exclusion criteria: age less than 18 years, greater than 70 years, concomitant other types of meniscal tears (such as horizontal, bucket handle, radial tears, etc.), history of previous knee joint surgery, and patients with a clear history of significant trauma.

MRI Analysis

The scanning data were obtained with a 3.0 T MRI device while the patient was in a supine position. MR images were acquired using the Picture Archiving and Communication System (PACS), and MRI assessment was performed using PACS software.

The diagnosis of MMPR tear in all cases was made by the "fissure sign" on the coronal plane and the "ghost sign" on the sagittal plane. The "fissure sign" in the coronal plane refers to the vertical high signal reaching the articular surface at the posterior root of the meniscus, showing a fissure-like change with varying widths. The "ghost sign" in the sagittal plane refers to the disappearance of the normal low signal at the posterior root of the meniscus located anterior to the tibial attachment of the posterior cruciate ligament, or obvious high signal changes. [4]

Measurement of the tear gap was performed on the coronal plane of MRI because the tibial attachment point of MMPR is most evident at this level. The tear gap of the medial meniscus root refers to the distance between the tear point and the inner surface of the displaced meniscus, recorded in millimeters (mm) (Fig. 1B). Based on the length of the tear gap, it was divided into two groups: ≤4 mm for mild displacement (M) group and > 4 mm for extensive displacement (W) group.

Meniscal extrusion was also measured on the coronal plane of MRI, with the measurement being the distance between the inner edge of the tibial plateau and the outer edge of the medial meniscus, recorded in millimeters (mm) (Fig. 1A).

On knee joint MRI, we graded the cartilage injury of the medial plateau of the tibia and the medial condyle of the femur according to the modified Outerbridge classification.[5] Grade 0: normal and intact cartilage; Grade 1: softening or blistering of cartilage with intact surface; Grade 2: superficial ulceration, scar tissue, or fissure formation involving less than 50% of the joint surface depth; Grade 3: deep ulceration, scar tissue, fissure formation, or cartilage flap involving 50% of the depth of the joint cartilage but not exposing the subchondral bone; Grade 4: full-thickness cartilage wear with exposure of subchondral bone. In the study, Grades 0, 1, and 2 were considered as low-grade cartilage injuries, while Grades 3 and 4 were considered as high-grade cartilage injuries. In addition, osteophytes, bone marrow edema, and subchondral cysts of the medial condyle of the femur and the medial plateau of the tibia were evaluated.

The evaluation of MMPR tear and other pathologies was performed by a radiologist with 20 years of experience in musculoskeletal radiology. Since our study mainly focused on medial compartment lesions, there was no assessment of fibular collateral ligament and lateral compartment osteochondral lesions.

Statistical Analysis

All data were analyzed using SPSS 20.0 software. Independent sample t-tests were used to compare the age distribution and meniscal extrusion between groups. Pearson's chi-square analysis was used to compare the frequency distribution of cartilage and bone lesions between the two groups (mild displacement group and extensive displacement group). Variables with a designated p-value < 0.05 were considered statistically significant.

The mild displacement group comprised 73 cases, including 70 females (96%) and 3 males (4%), with ages ranging from 52 to 63 years (mean age 56 years); the extensive displacement group consisted of 80 cases, including 75 females (94%) and 5 males (6%), with ages ranging from 55 to 65 years (mean age 57.5 years) (Table 1). There were no statistically significant differences in age or gender distribution between the two groups (p > 0.05).

Table 1

The absolute meniscal extrusion and lesions of cartilage and bone in mild displacement group and extensive displacement group
	Mild displacement group (n = 73 )	Extensive displacement group (n = 80)	P
Absolute meniscal extrusion (mm)	3.51 ± 0.82	4.52 ± 1.22	< 0.001
Cartilage injury of MFC			< 0.05
Low grade(Grade 1,2,3)(%)	38(52.1)	20(25)
High grade(Grade 3,4)(%)	35(47.9)	60(75)
Cartilage injury of MTP			< 0.05
Low grade(Grade 1,2,3)(%)	39(53.4)	35(43.8)
High grade(Grade 3,4)(%)	34(46.6)	45(56.2)
Bone lesions in MFC
Osteoproliferation(%)	68(93.1)	74(92.5)	>0.05
Bone marrow edema(%)	34(46.6)	45(56.2)	>0.05
Bone cyst(%)	15(20.5)	20(25)	>0.05
Bone lesions in MTP
Osteoproliferation(%)	66(90.4)	75(93.8)	>0.05
Bone marrow edema(%)	32(43.8)	43(53.8)	>0.05
Bone cyst(%)	17(23.3)	25(31.3)	>0.05
Y: YES; N: NO; MFC: medial condyle of the femur; MTP: medial plateau of the tibia.

In the mild displacement group, the mean medial meniscal extrusion distance was 3.5mm (range 1.5-5mm), while in the extensive displacement group, the mean medial meniscal extrusion distance was 4.53mm (range 2.5-7.3mm). The comparison between the two groups was statistically significant (P < 0.05). The degree of medial femoral condyle cartilage degeneration was more severe in the extensive displacement group compared to the mild displacement group, with statistical significance (P < 0.05). In the extensive displacement group, tibial cartilage degeneration, osteophyte formation, subchondral cyst formation, and narrowing of the medial compartment were more common, but there was no significant statistical difference compared to the mild displacement group (P > 0.05).

In recent years, as understanding of posterior root tears of the medial meniscus has deepened, studies have found that this type of tear can lead to meniscal extrusion, which is equivalent to total meniscectomy, accelerating the progression of knee osteoarthritis [6, 7, 8, 9]. However, there is currently little research on the relationship between MMPR tears and meniscal extrusion, and cartilage degeneration. According to the literature, the few studies available are also based on arthroscopic reports [1, 3]. This study, based on MRI imaging, analyzes the relationship between tear gap and meniscal extrusion, as well as medial compartment cartilage degeneration, which can effectively guide the prognosis and treatment of the disease.

Medial meniscal extrusion was measured on MRI images in the coronal plane. Absolute and relative extrusion values can be measured, where the absolute extrusion value refers to the horizontal distance from the inner edge of the medial meniscus to the edge of the tibial plateau, while the relative extrusion value refers to the ratio of the width of medial meniscal extrusion to the entire width of the meniscus. In our study, we chose to measure the absolute extrusion value because this method is faster, simpler, and easier to grasp. Our study found that as the amount of tear gap caused by MMPR tears increased, the absolute extrusion value of the meniscus also increased. Scholars such as Bin [10] found in studies based on arthroscopic observations of MMPR tears that compared to non-displaced MMPR tears, extensively displaced MMPR tears exhibit more severe meniscal extrusion, more severe cartilage wear, and osteoarthritic changes. Kim et al. found that in patients with MMPR tears, the mean absolute meniscal extrusion value was 4.02mm [1], Choi et al. suggested 3.8 mm [11], Kyrch et al. reported 4.4mm [12], while Ozkoc et al. found it to be 4.29mm [13]. Due to the varying reports in the studies of different scholars, among patients with posterior root tears of the medial meniscus, the average absolute meniscal extrusion value is around 4mm. In our study, we chose 4mm as the critical value to classify patients into mild displacement and extensive displacement groups. This way, we can more simply analyze the impact of meniscal extrusion on other accompanying joint pathologies. Our study found that in the mild displacement group, the mean absolute meniscal extrusion value was 3.51mm, while in the extensive displacement group, it was 4.52mm. Our average extrusion values are generally consistent with the literature. However, the absolute meniscal extrusion value in the extensive displacement group is significantly higher than that in the mild displacement group, suggesting that with larger tear gap distances, more meniscal extrusion occurs.

The meniscus mainly relies on its hoop effect to perform its shock absorption and stress dispersion functions. Once the medial meniscus root is ruptured, its function disappears as the hoop effect fails, leading to a decrease in tibiofemoral contact area and an increase in peak pressure per unit area [9, 14, 15]. Previous studies have shown that MMPR tears have biomechanical results similar to total meniscectomy, and after repair of the medial meniscus root, joint biomechanics can be restored to normal ranges [9]. These studies all indicate that after posterior root tears of the medial meniscus, stress on the medial compartment cartilage and subchondral bone tissue increases, leading to degeneration of bone and cartilage, which is closely related to the progression of osteoarthritis. Guermazi et al. reported that the relative risk of cartilage degeneration in MMPR tear patients is higher than in other degenerative medial meniscus tears [16]. Although many studies have reported on the relationship between medial meniscal extrusion and cartilage degeneration, there is currently very little direct research on the relationship between tear gaps caused by posterior root tears of the medial meniscus and cartilage damage [3, 10]. Kim et al. [3] and Bin et al. [10] found in arthroscopic observation studies that the larger the tear gap caused by MMPR tears, the more severe the medial femoral condyle cartilage damage. In our MRI-based analysis study, we also found that in the extensively displaced tear gap group, the medial femoral condyle cartilage damage was more severe than in the mild displacement group. With the prolongation of MMPR tear time, the long-term high physiological load on the knee joint may lead to an increase in tear gap and cartilage damage. In knee joint biomechanics, because the medial femoral condyle moves more frequently on the meniscus than the medial tibial plateau, medial femoral condyle cartilage damage is often more pronounced than that of the medial tibial plateau. In previous studies, medial tibial plateau cartilage damage has been considered the only cartilage characteristic associated with accelerated progression of knee joint osteoarthritis [17, 18]. Therefore, we believe that when evaluating MRI of posterior root tears of the medial meniscus, it is important to assess the area of knee joint cartilage damage.

Kim et al.[3] used 1mm as the critical value for tear gap in their study, dividing cases of MMPR tears into displacement group (≥ 1mm) and non-displacement group (< 1mm), and found that the displacement group had more severe cartilage wear and osteoarthritis. However, in our study, although osteophyte formation, subchondral cysts, and bone marrow edema were more pronounced in the extensive displacement group compared to the mild displacement group, there was no significant statistical difference between the two groups. However, the lack of significant differences between the two groups does not mean that MMPR tears are not a risk factor for subchondral bone changes, as our study did not provide a detailed scoring of cartilage damage. Our study has some limitations. It is a single-center and retrospective design. All patients in this study were degenerative MMPR tear patients, predominantly middle-aged women. Excessive effusion can cause joint capsule swelling and push the medial meniscus outward [19]. Although none of our cases had excessive effusion, the increase in intra-articular effusion may affect the position and extrusion value of the meniscus as we did not exclude cases of effusion. Another limitation is that the time from the formation of the posterior root tear of the medial meniscus to the MRI examination is not clear, and the length of this time may affect the degree of meniscal extrusion and the extent of cartilage damage.

The dimensional attributes of the tear gap engendered by medial meniscus root disruptions, as delineated via MRI, emerge as pivotal prognosticators of medial meniscus extrusion and osseous cartilaginous involution. These observations furnish clinicians with salient metrics to anticipate the trajectory of osteoarthritic evolution within a clinical context.

MMPR: medial meniscus posterior root

PACS: Picture Archiving and Communication System

MRI: magnetic resonance imaging

Acknowledgements

The authors would like to thank the patients and their families for support and cooperation.

Author contributions

Yongwei Zhou carried out the concepts, design, definition of intellectual content, literature search, data acquisition, data analysis, and manuscript preparation. Jiayu Kang provided assistance for data acquisition, data analysis, and statistical analysis. Yongwei Zhou carried out literature search, data acquisition, and manuscript editing. Qining Yang performed manuscript review. All authors have read and approved the content of the manuscript.

Funding

The study was funded by a study named “The Jinhua Science and technology research plan project (2020-4-014)” ,“The Jinhua Key Science and technology research plan project (2022-3-095)” and “Medical and Health Science and Technology Project of Zhejiang Province (2018278307)”.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Jinhua Central Hospital in accordance with the Declaration of Helsinki. All the patients included in this study provided signed informed consent.

Human Ethics and Consent to Participate declarations:

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Kim JY, Bin SI, Kim JM, Lee BS, Oh SM, Park MH. Tear gap and severity of osteoarthritis are associated with meniscal extrusion in degenerative medial meniscus posterior root tears. Orthop Traumatol Surg Res. 2019 Nov;105(7):1395-1399.
Lee YG, Shim JC, Choi YS, Kim JG, Lee GJ, Kim HK. Magnetic resonance imaging findings of surgically proven medial meniscus root tear: tear configuration and associated knee abnormalities. J Comput Assist Tomogr. 2008 May-Jun;32(3):452-7.
Kim JY, Bin SI, Kim JM, Lee BS, Oh SM, Cho WJ. A Novel Arthroscopic Classification of Degenerative Medial Meniscus Posterior Root Tears Based on the Tear Gap. Orthop J Sports Med. 2019 Mar 18;7(3):2325967119827945.
Randazzo, Elena MD; Duerr, Robert MD; Baria, Michael R. MD, MBA. Meniscus Root Tears: A Clinical Review. Current Sports Medicine Reports 21(5):p 155-158, May 2022.
Potter HG, Linklater JM, Allen AA, Hannafin JA, Haas SB. Magnetic resonance imaging of articular cartilage in the knee. An evaluation with use of fast-spin-echo imaging. J Bone Joint Surg Am. 1998 Sep;80(9):1276-84.
Sebro R, Ashok SS, Uriell M. Association between tears of the posterior root of the medial meniscus and far posterior femoral condyle osteoarthritis. Diagn Interv Radiol. 2020 Jul;26(4):349-354.
Okazaki Y, Furumatsu T, Yamaguchi T, Kodama Y, Kamatsuki Y, Masuda S, Okazaki Y, Hiranaka T, Zhang X, Ozaki T. Medial meniscus posterior root tear causes swelling of the medial meniscus and expansion of the extruded meniscus: a comparative analysis between 2D and 3D MRI. Knee Surg Sports Traumatol Arthrosc. 2020 Nov;28(11):3405-3415.
Yokoe T, Ouchi K, Yamaguchi Y, Enzaki M, Tajima T, Chosa E. Shear stress in the medial meniscus posterior root during daily activities. Knee. 2023 Aug;43:176-183.
Allaire R, Muriuki M, Gilbertson L, Harner CD. Biomechanical consequences of a tear of the posterior root of the medial meniscus. Similar to total meniscectomy. J Bone Joint Surg Am. 2008 Sep;90(9):1922-31.
Bin SI, Jeong TW, Kim SJ, Lee DH. A new arthroscopic classification of degenerative medial meniscus root tear that correlates with meniscus extrusion on magnetic resonance imaging. Knee. 2016 Mar;23(2):246-50.
Choi CJ, Choi YJ, Lee JJ, Choi CH. Magnetic resonance imaging evidence of meniscal extrusion in medial meniscus posterior root tear. Arthroscopy. 2010 Dec;26(12):1602-6.
Krych AJ, Johnson NR, Mohan R, Hevesi M, Stuart MJ, Littrell LA, Collins MS. Arthritis Progression on Serial MRIs Following Diagnosis of Medial Meniscal Posterior Horn Root Tear. J Knee Surg. 2018 Aug;31(7):698-704.
Ozkoc G, Circi E, Gonc U, Irgit K, Pourbagher A, Tandogan RN. Radial tears in the root of the posterior horn of the medial meniscus. Knee Surg Sports Traumatol Arthrosc. 2008 Sep;16(9):849-54.
Krych AJ, Johnson NR, Mohan R, Hevesi M, Stuart MJ, Littrell LA, Collins MS. Arthritis Progression on Serial MRIs Following Diagnosis of Medial Meniscal Posterior Horn Root Tear. J Knee Surg. 2018 Aug;31(7):698-704.
Chung KS, Ha JK, Ra HJ, Yu WJ, Kim JG. Root Repair Versus Partial Meniscectomy for Medial Meniscus Posterior Root Tears: Comparison of Long-term Survivorship and Clinical Outcomes at Minimum 10-Year Follow-up. Am J Sports Med. 2020 Jul;48(8):1937-1944.
Guermazi A, Hayashi D, Jarraya M, Roemer FW, Zhang Y, Niu J, Crema MD, Englund M, Lynch JA, Nevitt MC, Torner JC, Lewis CE, Felson DT. Medial posterior meniscal root tears are associated with development or worsening of medial tibiofemoral cartilage damage: the multicenter osteoarthritis study. Radiology. 2013 Sep;268(3):814-21.
Foreman SC, Liu Y, Nevitt MC, Neumann J, Joseph GB, Lane NE, McCulloch CE, Link TM. Meniscal Root Tears and Extrusion Are Significantly Associated with the Development of Accelerated Knee Osteoarthritis: Data from the Osteoarthritis Initiative. Cartilage. 2021 Dec;13(1_suppl):239S-248S.
Wluka AE, Stuckey S, Snaddon J, Cicuttini FM. The determinants of change in tibial cartilage volume in osteoarthritic knees. Arthritis Rheum. 2002 Aug;46(8):2065-72.
Miller TT, Staron RB, Feldman F, Cepel E. Meniscal position on routine MR imaging of the knee. Skeletal Radiol. 1997 Jul;26(7):424-7.

No competing interests reported.

Download PDF

Version 1

posted

You are reading this latest preprint version

The Impact of Posterior Root Tears of the Medial Meniscus on Meniscal Extrusion and Cartilage Degeneration

Status:

Version 1

Abstract

Figures

Background

Methods

Statistical Analysis

Results

Discussion

Conclusions

Abbreviations

Declarations

References

Additional Declarations

Status:

Version 1