A predictive model with radiographic signs can be a useful supplementary diagnostic tool for complete discoid lateral meniscus in adults

Excellent accuracy of magnetic resonance imaging for diagnosis of discoid meniscus tears: A systematic review and meta-analysis

Purpose

The discoid meniscus (DM) is distinguished by its thickened, disc-shaped formation, which extends over the tibial plateau. The likelihood of developing osteoarthritis escalates if a DM tear remains undiagnosed and untreated. While DM tears can be diagnosed through arthroscopy, the high cost, invasive nature and limited availability of this procedure highlight the need for a better diagnostic modality. This study aims to determine the accuracy of magnetic resonance imaging (MRI) in diagnosing DM tears.

Methods

A systematic review was conducted to gather articles with at least 10 cases on the comparison of MRI and arthroscopy as the gold standard for DM tear diagnosis. Stata and MetaDisc were used to conduct the statistical analysis. The quality of the included studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool.

Results

Five diagnostic performance studies, derived from four original research papers involving 305 patients, were evaluated. Based on the pooled data, the sensitivity, specificity, diagnostic odds ratio, positive limit of detection and negative limit of detection were found to be 0.87 (95% confidence interval [CI], 0.82-0.91) and 0.84 (95% CI, 0.75-0.90), 32.88 (95% CI, 5.81-186.02), 5.22 (95% CI, 1.71-15.92) and 0.18 (95% CI, 0.09-0.38), respectively. A hierarchical summary receiver operating characteristic curve with an area under the curve of 0.92 was generated.

Conclusion

This meta-analysis demonstrates that MRI has excellent sensitivity and specificity for diagnosing DM tears. Despite its lower accuracy compared to arthroscopy, MRI can be used in symptomatic patients as a viable alternative to arthroscopy due to its inherent advantages.

Level of Evidence

Level IV.

MRI Analysis of Knee Bony Morphology Variations in Children and Adolescents With Lateral Discoid Meniscus Compared With Asymptomatic Healthy Controls

BACKGROUND

Lateral discoid meniscus accounts for most meniscal tears in children 10 years of age and younger. The role of bony morphology in discoid meniscus has been previously studied in a limited capacity using radiographs.

PURPOSE

To use magnetic resonance imaging to measure features of the femoral condyles and tibial plateaus in patients with discoid meniscus to assess potential determinants of symptoms and subsequent surgery and to compare with matched controls to investigate age-related changes in bony features.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

After institutional review board approval, detailed morphology of the femoral condyles and tibial plateau was measured in 177 patients (3-18 years of age; 56% female) with confirmed lateral discoid meniscus. Measurements from 269 participants (3-18 years of age; 55% female) with asymptomatic knees were used as controls. Two-way analysis of variance with Holm-Šídák post hoc was used to compare measurements between discoid menisci and matched controls. Independent t tests were used to compare aspects of bony morphology within the discoid meniscus cohort.

RESULTS

Compared with controls, patients with a lateral discoid meniscus had a larger bicondylar width and notch width (7- to 10-year-old and 15- to 18-year-old age groups; P < .05), larger tibial plateau width (11- to 14-year-old and 15- to 18-year-old age groups; P < .001), and smaller lateral (P < .02) and coronal (P < .02) tibial slopes across all age groups. Among patients with a discoid meniscus, larger bicondylar width, larger tibial plateau width, larger notch width, and a flatter lateral femoral condyle were associated with pain (P < .005) and lateral meniscal tears (P < .02). Larger notch width and notch width index were also associated with subsequent surgery (P < .05).

CONCLUSION

There are clinically significant abnormalities in bony morphology in patients with a discoid meniscus, including larger femoral condyles and tibial plateaus and a flatter tibial plateau. Additionally, femoral size, femoral curvature, and tibial plateau size may influence the likelihood of knee pain, meniscal tear, and need for surgery. These findings highlight the importance of bony morphology in discoid meniscus pathophysiology in children and adolescents. Such measurements may also aid radiographic detection of discoid meniscus and guide decisions regarding the timing of potential surgical intervention.

Evaluation of tibial eminence morphology using magnetic resonance imaging (MRI) in juvenile patients with complete discoid lateral meniscus

Background

Many studies have shown that hypoplasia of knee bone morphology is related to the morphological features of the discoid lateral meniscus (DLM). However, few studies have focused on hypoplasia of tibial eminence morphology in juvenile patients with complete DLM. The purpose of this study was to determine the relationship between tibial eminence morphology characteristics and complete DLM in juvenile patients.

Methods

The DLM group comprised 34 juvenile patients with complete DLM, and the control group comprised 34 juvenile individuals, each with a normal lateral meniscus based on magnetic resonance imaging (MRI) findings. All parameters, including tibial width (TW), tibial eminence width (TEW), the height of the lateral tibial spine (HLTS), the height of the medial tibial spine (HMTS), lateral slope angle of the lateral tibial eminence (LSALTE), lateral slope angle of the medial tibial eminence (LSAMTE), tibial eminence width ratio (TEWR), height of the lateral tibial spine ratio (HLTSR), and the height of the medial tibial spine ratio (HMTSR), were recorded using coronal MR images. Statistical analyses were used to determine the differences between the two groups and whether differences were significant.

Results

The TEW and TEWR were significantly greater (P < 0.05), and LSALTE and LSAMTE were significantly smaller (P < 0.05) in patients in the DLM group than in participants in the control group. Receiver operating characteristic (ROC) analysis revealed that a larger TEW, above 13.4 mm, was associated with complete DLM, with a sensitivity of 77.0% and specificity of 88.2%, and a larger TEWR, above 19.7%, was associated with complete DLM, with a sensitivity of 76.5% and specificity of 91.2%.

Conclusions

MR imaging can be used to diagnose tibial eminence hypoplasia in juvenile patients with complete DLM. Additionally, TEW and TEWR could help clinicians screen for complete DLM in juvenile patients.

A radiographic model predicting the status of the anterior cruciate ligament in varus knee with osteoarthritis

Purpose

The study aims to investigate the accuracy of different radiographic signs for predicting functional deficiency of anterior cruciate ligament (ACL) and test whether the prediction model constructed by integrating multiple radiographic signs can improve the predictive ability.

Methods

A total number of 122 patients from January 1, 2018, to September 1, 2021, were enrolled in this study. Among them, 96 patients were classified as the ACL-functional (ACLF) group, while 26 patients as the ACL-deficient (ACLD) group after the assessment of magnetic resonance imaging (MRI) and the Lachman’s test. Radiographic measurements, including the maximum wear point of the proximal tibia% (MWPPT%), tibial spine sign (TSS), coronal tibiofemoral subluxation (CTFS), hip–knee–ankle angle (HKA), mechanical proximal tibial angle (mPTA), mechanical lateral distal femoral angle (mLDFA) and posterior tibial slope (PTS) were measured using X-rays and compared between ACLF and ACLD group using univariate analysis. Significant variables (p < 0.05) in univariate analysis were further analyzed using multiple logistic regression analysis and a logistic regression model was also constructed by multivariable regression with generalized estimating models. Receiver-operating-characteristic (ROC) curve and area under the curve (AUC) were used to determine the cut-off value and the diagnostic accuracy of radiographic measurements and the logistic regression model.

Results

MWPPT% (odds ratio (OR) = 1.383, 95% confidence interval (CI) = 1.193–1.603, p < 0.001), HKA (OR = 1.326, 95%CI = 1.051–1.673, p = 0.017) and PTS (OR = 1.981, 95%CI = 1.207–3.253, p = 0.007) were shown as predictive indicators of ACLD, while age, sex, side, TSS, CTFS, mPTA and mLDFA were not. A predictive model (risk score = -27.147 + [0.342*MWPPT%] + [0.282*HKA] + [0.684*PTS]) of ACLD using the three significant imaging indicators was constructed through multiple logistic regression analysis. The cut-off values of MWPPT%, HKA, PTS and the predictive model were 52.4% (sensitivity:92.3%; specificity:83.3%), 8.5° (sensitivity: 61.5%; specificity: 77.1%), 9.6° (sensitivity: 69.2%; specificity: 78.2%) and 0.1 (sensitivity: 96.2%; specificity: 79.2%) with the AUC (95%CI) values of 0.906 (0.829–0.983), 0.703 (0.574–0.832), 0.740 (0.621–0.860) and 0.949 (0.912–0.986) in the ROC curve.

Conclusion

MWPPT% (> 52.4%), PTS (> 9.6°), and HKA (> 8.5°) were found to be predictive factors for ACLD, and MWPPT% had the highest sensitivity of the three factors. Therefore, MWPPT% can be used as a screening tool, while the model can be used as a diagnostic tool.

Symptomatic discoid lateral meniscus shows a relationship between types and tear patterns, and between causes of clinical symptom onset and the age distribution

PURPOSE

Discoid meniscus is a congenital abnormality of the lateral meniscus and is seen more frequently in East Asia. The purpose of this study was to retrospectively assess the relationship between discoid lateral meniscus (DLM) types and tear patterns and causes of age-specific clinical symptom onset.

METHODS

Of 1650 arthroscopic surgeries over a 20-year period, 138 (105 patients) were performed for DLM and were evaluated in this study. The mean age at surgery was 21.5 ± 15.8 years. The DLM type was classified by Watanabe's classification, and tear patterns were classified by the modified Bin's classification as simple horizontal, complicated horizontal, longitudinal, radial, complex, and no tear. Additionally, patients were divided by age group (< 10, 10-19, 20-39, 40-59, and ≥ 60 years) and classified according to the causes of clinical symptom onset as follows: sports activities, minor trauma in daily living, and no traumatic episode.

RESULTS

The DLM was complete in 78 (56.5%) knees and incomplete in 60 (43.5%); no Wrisberg type DLM was observed. Simple horizontal and complicated horizontal tears were significantly more frequent in complete DLM, whereas radial tears and no tears were significantly more frequent in incomplete DLM (p < 0.0001). When classified by age group, 74 (53.6%) knees with DLMs were found in teenagers. Sports activities caused symptom onset significantly more often in teenagers, no traumatic episode caused symptom onset in patients aged < 10 years, and minor trauma in daily living caused symptom onset in patients aged 40-59 years and ≥ 60 years (p < 0.0001). No relationship was found between the age distribution and tear patterns; however, the absence of tears tended to be more common in teenaged patients, and complicated horizontal tears were more common in patients over 20 years of age.

CONCLUSION

Symptomatic DLM occurred most often in teenagers. A relationship was identified between the DLM types and tear patterns, which could be helpful in preoperative planning. Causes of clinical symptom onset in patients with DLM were characterised by age group, which might help clinicians to suspect the presence of DLM.

LEVEL OF EVIDENCE

Level IV.

Evaluation of knee bone morphology in juvenile patients with complete discoid lateral meniscus using magnetic resonance imaging

PURPOSE

The characteristic two-dimensional bone morphology in patients with a discoid lateral meniscus (DLM) has been described. However, the associated three-dimensional imaging findings have not been characterized. This study was performed to identify differences in the knee bone morphology between juvenile patients with a DLM and those with a normal meniscus using magnetic resonance (MR) imaging.

METHODS

The DLM group comprised 33 consecutive juvenile patients (33 knees) with a complete DLM, and the control group comprised 24 juvenile patients (24 knees) with normal menisci on the basis of MR imaging findings. Each MR image was evaluated to determine the anterior obliquity of the lateral tibial plateau (AOLTP), posterior obliquity of the lateral tibial plateau (POLTP), lowest point of the lateral femoral condyle (LPLFC), posterior lateral condylar angle (PLCA) and posterior medial condylar angle (PMCA). Statistical analyses were performed to determine the differences between the two groups.

RESULTS

The POLTP was significantly larger, the LPLFC was significantly more lateral, and the PLCA was significantly smaller in the DLM group than in the control group (p < 0.001, p < 0.001 and p < 0.001 respectively). However, there was no statistically significant difference in the AOLTP or PMCA between the two groups (p = 0.429 and p = 0.148, respectively).

CONCLUSIONS

Hypoplasia of the lateral femoral condyle and posterior lateral tibial plateau is recognized in juvenile patients with a complete DLM on coronal and axial MRI images.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Anatomical knee variables result in worse outcomes of lateral meniscal allograft transplantation with discoid lateral menisci than with nondiscoid lateral menisci

PURPOSE

To compare the clinical results of meniscal allograft transplantation (MAT) between patients with discoid lateral meniscus (DLM) and non-DLM (NDLM) and to analyse whether anatomical deformities cause worse clinical results in DLM patients.

METHODS

Patients who underwent unilateral MAT from 2005 to 2017, including 115 patients with DLMs or NDLMs, were included in this study. Clinical outcomes [International Knee Documentation Committee (IKDC) scores, Lysholm scores, Tegner scores, and visual analogue scale (VAS) scores] and radiographic and MRI data were assessed. Clinical outcomes and anatomical knee variables were analysed by multivariate stepwise regression.

RESULTS

After more than 2 years of follow-up, 9 patients were lost to follow-up, and 59 patients with DLM and 47 patients with NDLM were included. The mean postoperative results were significantly better than the preoperative data (P < 0.05) in both the DLM and NDLM groups. In addition, postoperative IKDC, Lysholm, and VAS scores but not Tegner scores were better in the NDLM group than in the DLM group. Several anatomical knee variables differed significantly between the NDLM and DLM groups and were associated with MAT outcomes. The condylar prominence ratio of the lateral and medial femoral condyles adjacent to the intercondylar notch and squaring of the lateral femoral condyle (the distance of the straight articular condylar surface) were independent factors significantly correlated with the Lysholm scores for MAT at last follow-up.

CONCLUSION

MAT improved knee function in both patients with DLM and patients with NDLM, but patients NDLM had better clinical outcomes than patients with DLM. The condylar prominence ratio and squaring of the lateral femoral condyle may underlie this result.

LEVEL OF EVIDENCE

III.

Clinical presentation, MRI and clinical outcome scores do not accurately predict an important meniscal tear in a symptomatic discoid meniscus

PURPOSE

Discoid menisci can be symptomatic from instability or a tear. A torn discoid meniscus is likely to require repair to preserve meniscal function and should not be missed. This is the first study to evaluate a range of pre-operative methods to predict the likelihood of a torn discoid meniscus.

METHODS

A retrospective analysis of prospectively collected data was performed. Clinical, radiographic and operative data were reviewed. Patients were grouped based on the presence of a tear or not during surgery. All patients underwent MRI scans pre-operatively which were validated with arthroscopy findings to calculate sensitivity. All patients completed Pedi-KOOS and Pedi-IKDC pre-operative scores.

RESULTS

There were 32 discoid menisci in 27 patients. Mean age at surgery was 10.4 years (6-16). Nineteen patients were female. Seventeen menisci were identified as torn at time of arthroscopy (53%), 15 were unstable but not torn. Clinical findings did not differentiate between the torn or unstable menisci. MRI was only 75% sensitive and 50% specific at identifying a torn discoid meniscus. There was no statistical difference between KOOS-child (n.s.) and Pedi-IKDC (n.s.) scores between the groups.

CONCLUSION

MRI is neither sensitive nor specific at identifying tears in discoid menisci. There is no difference in pre-operative outcome scores for patients with a torn or unstable discoid meniscus; pre-operative PROMs are a poor predictor of a meniscal tear. This study emphasises that pre-operative tests and clinical findings are not conclusive for identifying a meniscal tear and the operating surgeon should be vigilant in identifying and repairing tears at the time of surgery. Pre-operative findings poorly correlate to arthroscopic findings and potential surgical interventions required. Patients and parents/carers should, therefore, be appropriately counselled prior to surgery that post-operative measures are dependent on intra-operative findings and not pre-operative findings in patients.

LEVEL OF EVIDENCE

III.

Widening of the popliteal hiatus on sagittal MRI view plays a critical role in the mechanical signs of discoid lateral meniscus

PURPOSE

This study was undertaken to elucidate the clinical significance of widening of the popliteal hiatus on magnetic resonance imaging (MRI) after a torn discoid lateral meniscus (DLM).

METHODS

Included are 125 knees with meniscal disorders after arthroscopic surgery, divided according to preoperative MRI and symptoms into group A (torn DLM with mechanical symptoms,11 knees); group B (torn DLM without mechanical symptoms,41 knees); group C (asymptomatic DLM, 19 knees); and group D (medial meniscal tears, 54 knees). Popliteal hiatus width was measured on sagittal and coronal MRI. During arthroscopy, total meniscectomy or central partial meniscectomy combined repair of the remaining part was performed in group A and group B. Outcomes were evaluated with MRI, the Tegner, Lysholm Knee Scoring Scale, and visual analog scale (VAS) scores.

RESULTS

The preoperative width of the popliteal hiatus was significantly larger in group A than in groups C and D (P < 0.05) on both views. Group A had a wider popliteal hiatus on sagittal view compared with group B (P < 0.05); group B had a wider popliteal hiatus on coronal view compared with group D (P < 0.05). The width of the popliteal hiatus on sagittal view was significantly reduced after surgery in group A (P < 0.05). In groups A and B, Lysholm and Tegner scores were improved, while VAS scores were reduced (all P < 0.05).

CONCLUSION

Widening of the popliteal hiatus on MRI was correlated with torn DLM and accompanied mechanical symptoms. Arthroscopic central partial menisectomy and stabilization of the posterior part of the middle body anterior to the popliteus tendon were effective for the treatment of torn DLM. These findings may help guide appropriate treatment for torn DLM.

LEVEL OF EVIDENCE

II.