The menisci are fibrocartilaginous structures located between the femoral condyles and tibial plateau and are essential for normal knee biomechanics. They contribute to load transmission, shock absorption, joint stability, lubrication and distribution of contact stresses across the articular surfaces. Removal or significant loss of meniscal tissue can increase focal contact stresses and may contribute to progressive cartilage degeneration. Consequently, contemporary management of meniscal injuries increasingly emphasizes preservation and repair of functional meniscal tissue whenever feasible.1-7 Meniscal tears occur following both acute traumatic events and degenerative processes. In younger individuals, tears are commonly associated with twisting injuries, sports activities and concomitant ligamentous injury, whereas degenerative meniscal pathology becomes increasingly common with advancing age and may occur in association with osteoarthritic changes.4-7 The morphology of tears is highly variable and includes longitudinal, horizontal, radial, bucket-handle, flap and complex patterns.7-10 The clinical presentation may include joint-line pain, swelling, mechanical locking, clicking and a sensation of instability. Clinical tests such as McMurray's test, joint-line tenderness and other provocative manoeuvres can support the diagnosis; however, clinical examination alone may not adequately characterize the morphology or extent of a tear.⁹ MRI therefore has an important role in the evaluation of patients with suspected internal derangement of the knee.11-14 MRI provides multiplanar visualization of the menisci and associated structures without ionizing radiation. Systematic reviews have demonstrated high diagnostic accuracy of MRI for both medial and lateral meniscal tears, supporting its role as the principal non-invasive imaging modality for suspected meniscal injury.8,12 Despite its high diagnostic accuracy for detecting meniscal tears, MRI interpretation may vary with respect to terminology and detailed morphological characterization. This is particularly relevant when determining whether a tear is suitable for repair.14-16 Standardized terminology can improve communication between radiologists and orthopaedic surgeons and may facilitate treatment planning. The International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) classification provides a standardized system for describing meniscal tears according to clinically relevant parameters, including tear pattern, depth, rim width, radial location, tissue quality and tear length.16-20 The classification was developed to improve consistency in arthroscopic documentation and communication regarding meniscal pathology.20 Previous research has demonstrated that the ISAKOS system can also be applied to MRI. Chhabra et al. evaluated MRI-based application of the ISAKOS classification and demonstrated correlation between MRI and arthroscopic assessment of meniscal tears.16,17 Other investigators have reported satisfactory intermethod and inter-rater reliability between MRI and arthroscopy, although agreement varies among individual parameters.18,19 The clinical relevance of standardized classification is considerable. A conventional MRI report that simply identifies a "meniscal tear" may provide insufficient information for surgical planning. In contrast, documentation of tear configuration, depth, location, peripheral extension, tissue quality and estimated length provides the surgeon with a more comprehensive preoperative assessment.16-20 Therefore, the present study was undertaken to evaluate the correlation between MRI and arthroscopic assessment of meniscal tears using the ISAKOS classification in patients undergoing knee arthroscopy at Hind Institute of Medical Sciences, Mau, Ataria, Sitapur, Uttar Pradesh. The objectives of the study are as below: 1. To characterize meniscal tears on MRI using the ISAKOS classification. 2. To compare MRI and arthroscopic findings with respect to tear pattern. 3. To compare tear depth, rim-width zone and radial location between MRI and arthroscopy. 4. To evaluate the correlation of MRI and arthroscopic assessment of meniscal tissue quality. 5. To compare tear-length measurements obtained by MRI and arthroscopy. 6. To determine the overall agreement between MRI and arthroscopic characterization of meniscal tears.

This prospective observational study was planned in the Department of Orthopaedics, Hind Institute of Medical Sciences, Mau, Ataria, Sitapur, Uttar Pradesh, India. The study population consisted of adult patients presenting with clinical features suggestive of meniscal pathology who underwent MRI evaluation followed by knee arthroscopy. The study protocol should be submitted to the Institutional Ethics Committee of Hind Institute of Medical Sciences, Mau, Ataria, Sitapur, Uttar Pradesh, before initiation of patient recruitment. Written informed consent should be obtained from all participants. Sample size: A total of 60 patients were included in the proposed study. The sample size was selected within the predefined range of 50–60 participants and was considered feasible for a single-centre prospective observational study. Inclusion criteria 1. Age ≥18 years. 2. Either sex. 3. Clinical suspicion of meniscal injury. 4. MRI evidence of a meniscal tear. 5. Subsequent knee arthroscopy. 6. Written informed consent. Exclusion criteria 1. Previous surgery involving the affected meniscus. 2. Inadequate MRI images or major motion/susceptibility artefacts. 3. Incomplete MRI sequences. 4. Previous major trauma resulting in severe distortion of knee anatomy. 5. Incomplete arthroscopic documentation. 6. Refusal to participate. Clinical assessment: A detailed history was obtained regarding age, sex, mechanism of injury, duration of symptoms, affected knee, pain, swelling, locking, clicking and instability. Clinical examination included assessment of range of movement, joint-line tenderness, effusion, ligamentous stability and appropriate meniscal provocative tests. MRI assessment: MRI of the affected knee was performed using standard knee MRI protocols with multiplanar sequences. The medial and lateral menisci were assessed systematically. The presence of a meniscal tear was documented when abnormal intrameniscal signal extended to an articular surface and/or when there was abnormal meniscal morphology. Each tear was characterized using the ISAKOS classification. Tear pattern Tears were categorized as: • Longitudinal • Horizontal • Radial • Bucket-handle • Horizontal flap • Complex Tear depth Tears were categorized as: • Partial • Complete • Rim width Peripheral extension was classified into: • Zone 1: <3 mm • Zone 2: 3–5 mm • Zone 3: >5 mm Radial location The tear was localized to: • Anterior • Middle/body • Posterior Tissue quality Tissue was categorized as: • Non-degenerative • Degenerative Tear length: The maximum measurable length of the tear was recorded in millimetres. For lateral meniscal tears, relationship with the popliteal hiatus was also documented. Arthroscopic assessment: All patients subsequently underwent knee arthroscopy. Standard anterolateral and anteromedial portals were used. The medial and lateral compartments were systematically examined. The menisci were inspected directly and probed to determine tear morphology, extent, stability and tissue quality. Arthroscopic findings were recorded using the same ISAKOS variables used for MRI assessment. Statistical analysis: Data were entered into a computerized database and analysed using appropriate statistical software. Continuous variables were expressed as mean ± standard deviation. Categorical variables were presented as frequencies and percentages. Agreement between MRI and arthroscopy for categorical variables was assessed using Cohen's kappa coefficient. Kappa values were interpreted as follows: • <0.20: poor • 0.21–0.40: fair • 0.41–0.60: moderate • 0.61–0.80: good • 0.80: excellent For tear length, intraclass correlation coefficient was calculated. MRI and arthroscopic measurements were compared using a paired statistical test. A p-value <0.05 was considered statistically significant.

A total of 60 patients were included. The mean age was 34.6 ± 11.7 years, with patients ranging from 19 to 62 years. The largest proportion of participants belonged to the 31–40-year age group. Male patients constituted 70.0% of the study population. The right knee was involved in 32 (53.3%) patients and the left knee in 28 (46.7%) as shown in table 1. Table 1. Demographic characteristics of study participants Characteristic Number Percentage Age group ≤20 years 3 5.0 21–30 years 17 28.3 31–40 years 22 36.7 41–50 years 11 18.3 >50 years 7 11.7 Sex Male 42 70.0 Female 18 30.0 Side involved Right 32 53.3 Left 28 46.7 Among the 60 patients, 64 meniscal tears were identified because four patients had tears involving both medial and lateral menisci. The medial meniscus accounted for 37 (57.8%) tears, while 27 (42.2%) involved the lateral meniscus. There was complete agreement between MRI and arthroscopy regarding identification of the involved meniscus in the simulated dataset (table 2). Table 2. Distribution of meniscal tears Meniscus MRI Arthroscopy Medial 37 (57.8%) 37 (57.8%) Lateral 27 (42.2%) 27 (42.2%) Total 64 (100%) 64 (100%) Longitudinal tears represented the most common tear pattern, followed by complex and radial tears. The overall agreement between MRI and arthroscopy for tear pattern was good (κ=0.74). Most discrepancies involved differentiation between longitudinal and complex tears (table 3). Table 3. Comparison of tear pattern between MRI and arthroscopy Tear pattern MRI n (%) Arthroscopy n (%) Longitudinal 14 (21.9) 15 (23.4) Complex 15 (23.4) 14 (21.9) Radial 12 (18.8) 12 (18.8) Horizontal 8 (12.5) 8 (12.5) Bucket-handle 9 (14.1) 9 (14.1) Horizontal flap 6 (9.4) 6 (9.4) Total 64 (100) 64 (100) On MRI, 19 (29.7%) tears were categorized as partial and 45 (70.3%) as complete. Arthroscopy demonstrated 21 (32.8%) partial and 43 (67.2%) complete tears. Agreement for tear depth was good (κ=0.72). Table 4. Comparison of tear depth Tear depth MRI n (%) Arthroscopy n (%) Partial 19 (29.7) 21 (32.8) Complete 45 (70.3) 43 (67.2) Total 64 (100) 64 (100) Zone 3 involvement was the most frequent category. Agreement for rim-width classification was moderate (κ=0.57). Most discrepancies occurred between adjacent zones. Table 5. Comparison of rim-width classification Rim-width zone MRI n (%) Arthroscopy n (%) Zone 1 13 (20.3) 15 (23.4) Zone 2 23 (35.9) 22 (34.4) Zone 3 28 (43.8) 27 (42.2) Total 64 (100) 64 (100) The posterior region was the most commonly affected site. The agreement for radial location was good (κ=0.79) as shown in table 6. Table 6. Comparison of radial location Location MRI n (%) Arthroscopy n (%) Anterior 10 (15.6) 11 (17.2) Middle/body 24 (37.5) 23 (35.9) Posterior 30 (46.9) 30 (46.9) Total 64 (100) 64 (100) Agreement between MRI and arthroscopy for tissue quality was moderate (κ=0.52). MRI classified fewer tears as degenerative than arthroscopy. Arthroscopy identified subtle fraying and fibrillation in several cases that were not clearly appreciated on MRI (table 7). Table 7. Comparison of tissue quality Tissue quality MRI n (%) Arthroscopy n (%) Non-degenerative 46 (71.9) 42 (65.6) Degenerative 18 (28.1) 22 (34.4) Total 64 (100) 64 (100) The mean tear length on MRI was 21.6 ± 9.8 mm compared with 20.1 ± 9.1 mm on arthroscopy. There was a statistically significant difference between MRI and arthroscopic tear-length measurements, with MRI producing slightly larger measurements. However, the ICC of 0.86 demonstrated excellent correlation (table 8). Table 8. Comparison of tear length Parameter MRI Arthroscopy Mean tear length 21.6 ± 9.8 mm 20.1 ± 9.1 mm Mean difference 1.5 mm ICC 0.86 Paired comparison p-value 0.012 The strongest correlation was observed for tear length, while the lowest agreement was observed for tissue quality (table 9). Table 9. Agreement between MRI and arthroscopy according to ISAKOS parameters Parameter Agreement statistic Interpretation Tear pattern κ=0.74 Good Tear depth κ=0.72 Good Rim width κ=0.57 Moderate Radial location κ=0.79 Good Tissue quality κ=0.52 Moderate Tear length ICC=0.86 Excellent

Meniscal tears represent an important cause of knee pain, locking, instability and functional limitation. Accurate identification of tear morphology is particularly relevant because the current treatment philosophy emphasizes preservation of meniscal tissue whenever possible. Meniscal removal may increase focal contact stress and contribute to subsequent cartilage degeneration.¹⁻⁷ Therefore, imaging methods that can reliably define tear characteristics have an important role in clinical decision-making. MRI has become an integral component of the evaluation of suspected meniscal pathology. Its major advantages include non-invasive multiplanar imaging and simultaneous evaluation of associated ligamentous, cartilage and osseous abnormalities. MRI is particularly useful for identifying the presence and general configuration of meniscal tears. Previous studies have demonstrated high diagnostic accuracy of MRI for meniscal pathology.12-19 However, the description of a meniscal tear is not always standardized. Terms such as complex tear, radial tear, horizontal tear and degenerative tear may be interpreted differently depending on the radiologist or surgeon. This lack of standardized terminology can lead to inconsistencies in communication and documentation. The ISAKOS classification was developed to address this problem by providing a structured approach to meniscal tear characterization. The present hypothetical study demonstrated good overall correlation between MRI and arthroscopy when the ISAKOS classification was used. The overall agreement for tear pattern was κ=0.78, indicating good agreement. This finding suggests that MRI can accurately identify the predominant configuration of most meniscal tears when a standardized classification system is applied. Complex tears were the most frequently observed tear pattern in the present model dataset. This is consistent with the findings reported by Shah et al., in which complex tears represented the most common tear type on both arthroscopy and MRI. In their study, complex tears accounted for 32.0% of arthroscopic findings and 35.8% of MRI findings. The high agreement observed for complex and bucket-handle tears is clinically relevant. These tear patterns frequently have important implications for operative management. Bucket-handle tears may result in displaced fragments and mechanical symptoms, whereas complex tears may require careful evaluation to determine whether repair is technically feasible. In the present model study, MRI and arthroscopy demonstrated good agreement for tear depth (κ=0.76). Determination of whether a tear is partial or complete is clinically useful because deeper tears may have greater mechanical significance and may influence surgical planning. Assessment of rim width showed only moderate agreement (κ=0.58). This finding is plausible because accurate determination of the distance of a tear from the free edge may be difficult on MRI, particularly when the tear is irregular or extends across multiple zones. The reference study similarly reported lower agreement for some rim-width categories, with particularly low agreement in certain zones. Rim width has considerable clinical importance because it provides information regarding the peripheral location of the tear and may contribute to assessment of vascularity and reparability. Nevertheless, MRI cannot completely reproduce the tactile information available during arthroscopic probing. Consequently, the final assessment of stability and tissue quality may require direct arthroscopic examination. The agreement for tissue quality in the present study was moderate (κ=0.55). This was one of the weaker areas of MRI–arthroscopy correlation. Tissue quality is inherently more difficult to assess radiologically than tear configuration. Degenerative changes may manifest as increased intrameniscal signal, irregular morphology or fibrillation, but subtle surface fibrillation and free-edge fraying may be better appreciated during arthroscopy. Shah et al. noted that myxoid signal may not be visible during arthroscopy, while free-edge fibrillation and fraying may be better identified arthroscopically. The authors therefore suggested that tissue quality and rim width may not be adequately assessed using MRI alone when planning meniscal repair. The present study demonstrated excellent agreement for radial location (κ=0.81). Posterior tears were the most frequent location. Accurate localization of a meniscal tear is important for surgical planning and for communication between the radiologist and surgeon. Posterior horn tears, particularly of the medial meniscus, are common and may be associated with other internal derangements. Tear length showed excellent correlation between MRI and arthroscopy, with an ICC of 0.88. MRI measured slightly greater tear lengths than arthroscopy. This tendency has been reported previously. Shah et al. found that medial meniscal tears were significantly larger on MRI than on arthroscopy at both 1.5 T and 3.0 T. Several factors may explain this difference. MRI provides a comprehensive view of the entire meniscus and can visualize extensions that may be difficult to inspect arthroscopically. Arthroscopy provides direct visualization but may have limitations related to the field of view, displaced fragments and access to particular areas. In addition, measuring tear length during arthroscopy may involve approximation using a surgical probe, potentially introducing measurement error. The findings reinforce the complementary nature of MRI and arthroscopy. MRI provides a comprehensive, non-invasive assessment before surgery, while arthroscopy provides direct visualization, probing and assessment of mechanical stability. MRI can therefore assist in determining the likely tear pattern and extent before surgery, while arthroscopy remains important for final assessment and treatment. The use of a standardized classification system has particular importance in this context. When MRI and arthroscopy use the same terminology, comparison between the two modalities becomes more meaningful. It also facilitates communication between radiologists and surgeons. The reference study concluded that use of ISAKOS classification could improve multidisciplinary communication and aid in patient management and longitudinal assessment. The present study also has implications for routine orthopaedic practice. In many clinical settings, MRI reports may identify a meniscal tear but may not systematically describe its depth, radial location, peripheral extension, tissue quality or length. A structured ISAKOS-based report could provide more clinically useful information. For example, a report stating simply "medial meniscus tear" provides considerably less information than a report describing a "complete longitudinal tear involving the posterior horn and body, extending through zones 2 and 3, with non-degenerative tissue and a measured length of approximately 20 mm." The latter description allows the treating surgeon to anticipate the pathology more accurately and plan the arthroscopic procedure. The reference literature also indicates that both 1.5-T and 3.0-T MRI can be used for ISAKOS classification. Shah et al. reported generally satisfactory agreement on both field strengths, with no major overall differences except for certain measurements of tear length and improved zonal identification on 3.0-T imaging. Although the present study was not designed primarily to compare MRI field strengths, its findings support the broader principle that standardized interpretation may be more important than simply increasing imaging field strength. Appropriate sequence selection, multiplanar imaging and structured interpretation remain fundamental. The study has several strengths. First, MRI findings were compared directly with arthroscopic findings, allowing evaluation against the surgical reference standard. Second, the same classification terminology was used for both modalities. Third, both categorical and continuous variables were assessed using appropriate statistical measures. Finally, the study addresses a clinically important question relevant to preoperative planning. Limitations 1. The study sample was relatively small and derived from a single institution. 2. Only patients proceeding to arthroscopy were evaluated. 3. MRI-negative patients were not included in the MRI–arthroscopy correlation analysis. 4. Tissue quality cannot be completely assessed using MRI morphology alone. 5. Rim-width classification may be affected by partial-volume effects and differences in interpretation. 6. Tear length may vary slightly according to the measurement technique used. 7. The study did not compare different MRI field strengths. 8. The results presented in this draft are simulated and must be replaced with actual patient-level calculations before submission. Despite these limitations, the findings support the use of the ISAKOS classification as a practical framework for standardized MRI reporting of meniscal tears. Larger prospective multicentric studies involving larger numbers of patients and independent radiologists and surgeons could further establish its applicability.

MRI demonstrated good agreement with arthroscopy for characterization of meniscal tear pattern, depth and radial location when the ISAKOS classification was applied systematically. Tear length showed excellent correlation between MRI and arthroscopy, although MRI demonstrated a small tendency to produce greater measurements. Rim-width classification and tissue quality showed comparatively lower agreement, indicating that these parameters may remain challenging to assess accurately using MRI alone. Arthroscopy continues to provide important information regarding tissue quality, tear stability and reparability. The ISAKOS classification provides a structured and clinically meaningful framework for MRI reporting of meniscal tears. Its routine application may improve communication between radiologists and orthopaedic surgeons, facilitate preoperative planning and provide more standardized documentation of meniscal pathology. Larger prospective multicentric studies using actual patient-level data are required to further validate the classification and establish its reproducibility across different MRI protocols and clinical settings

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