Clinical, MRI, and Arthroscopic Findings Associated with Failure to Diagnose a Lateral Meniscal Tear on Knee MRI

Magnetic Resonance Imaging Indirect Signs for Anterior Instability of the Lateral Meniscus in Pediatric and Adolescent Patients

BACKGROUND

Anterior instability (AI) of the LM is potentially debilitating in young patients. The use of magnetic resonance imaging (MRI) to diagnose AI is limited due to the lack of reliable and accurate MRI findings. The ability to identify AI preoperatively would potentially improve the diagnosis and treatment of this pathology. This study presents a novel MRI finding ("phantom sign") for the detection of AI of the LM and demonstrates its reliability and accuracy.

METHODS

Three independent blinded reviewers performed retrospective review of preoperative MRI for all patients who underwent LM repair between July 1, 2019, and March 31, 2022, at a single center. Positive phantom sign was defined as abnormal signal intensity on MRI of the anterior horn of the LM on the coronal sequence at the anterior tibial insertion of the anterior cruciate ligament (ACL). Preoperative MRI was also evaluated for other signs of LM anterior instability. Intrarater and inter-rater reliability was assessed for rater scoring of presence of pathology on MRI. Predictive ability of each imaging finding with at least good (ICC 0.6 or above) reliability was also evaluated based on documented intraoperative findings.

RESULTS

Fifty-five preoperative MRIs of arthroscopically treated LM tears were reviewed. Median age was 15 years (range 6 to 20), and 21 patients (38.2%) were female. Twenty-seven patients (49.1%) had a discoid meniscus. LM AI was present on arthroscopy for 25 knees (45.45%), and among these, 21 had discoid morphology. Interrater reliability was substantial for phantom sign (ICC 0.71, 97.5% CI: 0.55-0.82), posterior displacement (ICC 0.71, 97.5% CI: 0.55-0.82), and posterior "megahorn" (ICC 0.76, 97.5% CI: 0.62-0.85). On predictive analysis, phantom signs were 98% sensitive and 76.7% specific for LM AI. Posterior displacement and posterior megahorn were specific for AI (both 93.34%), though with limited sensitivity (32% and 28.6%, respectively).

CONCLUSIONS

Phantom sign is a reliable and sensitive MRI finding for anterior instability, even in the absence of frank displacement on preoperative MRI. A positive finding should prompt a thorough arthroscopic evaluation of the anterior horn of the LM.

LEVEL OF EVIDENCE

Level III-case control study.

Risk factors for false positive and false negative MRI in diagnosing medial and lateral meniscal tears with concomitant ACL injury

OBJECTIVE

To determine the diagnostic performance of MRI in evaluating meniscal abnormalities in the setting of anterior cruciate ligament (ACL) injury and recognize predictors of false positive (FP) and false negative (FN) MRI diagnosis.

MATERIAL AND METHODS

Four hundred twenty patients (mean age, 27.2 years; 326 males, 94 females) who underwent arthroscopy for ACL injury between January 2017 and August 2022, and had preoperative imaging within 4 months, were retrospectively included. Images were independently interpreted by two experienced musculoskeletal radiologists, noting the presence of medial and lateral meniscal tears including tear type and location. Results were correlated with arthroscopic findings. Multivariate logistic regression was implemented to study risk factors (RF) for FP and FN MRI diagnosis.

RESULTS

The sensitivity/specificity/positive predictive value/negative predictive value/accuracy of MRI for medial meniscus tear was 97.5%/74.46%/65.63%/98.35%/82.15%; for lateral meniscus tear, it was 83.5%/93.70%/70.8%/94.55% /87.86%, with substantial interreader agreement. Female gender (odds ratio (OR), 0.434), posterior horn and posterior root tears (OR, 3.268/22.588), horizontal tear (OR, 3.134), and ramp lesion (OR, 4.964) were found RF for FP medial meniscus, and meniscal body tears (OR, 308.011) were found RF for FP lateral meniscus. RF for FN medial meniscus were meniscal tear at the posterior horn, body, and posterior root (OR, 12.371/123.000/13.045).

CONCLUSION

MRI is an effective screening tool for meniscal tears, but less accurate in detecting all medial meniscus injuries. Gender, meniscal tear location, and type increased the risk of FP medial meniscal tear on MRI, while meniscal tear location increased the risk of FP lateral meniscus and FN medial meniscus tears.

Degenerative medial and lateral menisci root tears: demographics, clinical presentation, imaging features, and associated findings

PURPOSE

(I) Characterize the demographics and clinical features of patients with meniscal root tears (MRT); (II) analyze the morphology, extent, and grade of MRT on MRI; (III) evaluate associated abnormalities on imaging; and (IV) evaluate the associations between imaging findings, demographics, clinical features, and joint structural abnormalities.

MATERIAL AND METHODS

A search was performed to identify meniscal root tears. Age, sex, BMI, and pain were recorded. Knee radiographs and MRI were reviewed. Presence, grade and morphology of MRT, meniscal extrusion, insufficiency fractures, as well as joint structural abnormalities were scored. For goals (I), (II), and (III), tabulations for categorical variables and mean for continuous variables were computed. MRT findings variables were described using percentages. For goal (IV), adjusted linear and logistic regression were employed.

RESULTS

Ninety-six patients with a mean age of 56.6 years (69 females) and mean BMI of 28.9 kg/m2 were included; 88 of the MRT were located at the posterior horn of the medial meniscus (PHMM), and 82% were radial tear. The mean tear diameter was 3.8 mm, and 78/96 tears presented with meniscal extrusion. Nineteen patients presented with subchondral insufficiency fracture (SIF), which was significantly associated with the gap of the tear (p = 0.001) and grade of the meniscal root lesion (p = 0.005).

CONCLUSION

MRT typically found in middle-aged to older overweight and obese women. Lesions were mostly radial tears and located at PHMM and were frequently associated with meniscal extrusion and SIF. Moreover, the presence of SIF was significantly associated with the gap width and grade of root tear.

Correlation of preoperative CT imaging shift parameters of the lateral plateau with lateral meniscal injury in Schatzker IV-C tibial plateau fractures

BACKGROUND

Schatzker IV-C is a high-energy tibial plateau fracture often accompanied by lateral meniscus injuries. While imaging examinations are routine preoperative measurements, the correlation between CT imaging shift parameters of the lateral plateau and lateral meniscal injury in Schatzker IV-C fractures remains uncovered.

METHODS

This retrospective study enrolled a total of 60 patients with Schatzker IV-C tibial plateau fractures at the First People's Hospital of Hefei. Prior to surgery, CT imaging was used to measure the numerical values of lateral plateau depression (LPD) and lateral plateau widening (LPW). The degree of lateral meniscus injury was confirmed based on intraoperative direct vision, with patients being classified into meniscus injury and non-meniscus injury groups. Dichotomous logistic regression was employed to evaluate the correlation between LPD, LPW, and lateral meniscus injury, while the optimal cut-off points for predicting lateral meniscal injury with LPD and LPW were determined using receiver operator characteristic (ROC) curves.

RESULTS

The meniscus injury group exhibited a mean LPD of 15.3 ± 3.5 mm, which was significantly higher than the non-meniscus injury group's mean LPD of 8.4 ± 3.4 mm (P < 0.05). Similarly, the meniscus injury group had a larger mean LPW of 9.4 ± 1.8 mm compared to the non-meniscus injury group's mean LPW of 6.9 ± 0.9 mm (P < 0.05). The optimal cut-off points for predicting lateral meniscal injury were determined to be 8.40 mm for LPD (with a sensitivity of 95%, specificity of 85%, and AUC of 0.898) and 7.90 mm for LPW (with a sensitivity of 75%, specificity of 90%, and AUC of 0.897).

CONCLUSIONS

Patients with Schatzker IV-C tibial plateau fractures are at a significantly higher risk of lateral meniscal injury when the LPD exceeds 8.40 mm and/or the LPW exceeds 7.90 mm. Our results may provide novel reference metrics for the early diagnosis of lateral meniscal injury in Schatzker IV-C tibial plateau fracture patients when the MRI examination is not available.

Analysis of Discordant Findings between 3T Magnetic Resonance Imaging and Arthroscopic Evaluation of the Knee Meniscus

Numerous studies have assessed the performance of magnetic resonance imaging (MRI) in detecting tears of the knee menisci using arthroscopy results as the gold standard, but few have concentrated on the nature of discordant findings. The purpose of this study was to analyze the discordances between 3T MRI and arthroscopic evaluation of the knee meniscus. Medical records of 112 patients who underwent 3T MRI and subsequent arthroscopy of the knee were retrospectively analyzed to determine the accuracy of diagnoses of meniscal tear. Compared with arthroscopy, there were 22 false-negative and 14 false-positive MR interpretations of meniscal tear occurring in 32 patients. Images with errors in diagnosis were retrospectively reviewed by two musculoskeletal radiologists in consensus and all errors were categorized as either unavoidable, equivocal or as interpretation error. Of 36 MR diagnostic errors, there were 16 (44%) unavoidable, 5 (14%) interpretation errors and 15 (42%) equivocal for meniscal tear. The largest categories of errors were unavoidable false-positive MRI diagnoses (71%) and equivocal false-negative MRI diagnoses (50%). All meniscal tears missed by MRI were treated with partial meniscectomy (n = 14) or meniscal repair (n = 8). Discordant findings between 3T MRI and arthroscopic evaluation of the knee meniscus remain a concern and primarily occur due to unavoidable and equivocal errors. Clinicians involved in the diagnosis and treatment of patients with meniscal tears should understand why and how the findings seen on knee MRI and arthroscopy may sometimes differ.

MR Imaging of Acute Knee Injuries: Systematic Evaluation and Reporting

Acute knee injury ranges among the most common joint injuries in professional and recreational athletes. Radiographs can detect joint effusion, fractures, deformities, and malalignment; however, MR imaging is most accurate for radiographically occult fractures, chondral injury, and soft tissue injuries. Using a structured checklist approach for systematic MR imaging evaluation and reporting, this article reviews the MR imaging appearances of the spectrum of traumatic knee injuries, including osteochondral injuries, cruciate ligament tears, meniscus tears and ramp lesions, anterolateral complex and collateral ligament injuries, patellofemoral translation, extensor mechanism tears, and nerve and vascular injuries.

Etiology of posterior meniscus root tears: medial vs. lateral

PURPOSE

The aim of this study was to generate more information on the etiology and pathogenesis of medial (MM) and lateral (LM) meniscus root tears. Our hypothesis was that root tears of the MM predominantly result from degenerative damage, whereas root injuries of the LM are mainly of traumatic origin.

METHODS

Consecutively, 53 patients with a root tear of the medial meniscus (MMRT) and 51 patients with a root tear of the lateral meniscus (LMRT) were included in this study. The diagnosis was confirmed radiologically by MRI as well as arthroscopically. In addition to patient-specific data such as age, BMI and trauma history, the leg axis was determined and accompanying injuries (ligamentous and chondrogenic) were documented.

RESULTS

The mean age of the MMRT group was 57.2 (± 11.2) years, and that of the LMRT group 33.9 (± 11.4) years. The BMI was significantly higher in the MMRT group compared to the LMRT (30.5 vs. 25.1). 82.4% of patients in the LMRT group demonstrated an accompanying anterior cruciate ligament (ACL) rupture, whereas only 5.7% of the MMRT were associated with an ACL injury. A trauma was described in only 13.2% of patients of the MMRT group in contrast to 88.2% of the LMRT group. An extrusion > 3 mm of the MM in the coronal plane of MRI images could be detected in 86.8% of patients, whereas in the LMRT group, it was 15.7%. The mechanical varus angle was 5.6° in the MMRT group and 2.4° in the LMRT group. The rate and degree of concomitant cartilage damage in the affected compartment was significantly higher in the group with medial root injuries than in the group with lateral root tears.

CONCLUSIONS

The root injuries of the MM and LM show significant differences in terms of patient age, etiology and accompanying injuries. Root injuries to the medial meniscus are mostly of non-traumatic origin and more likely to occur in the context of medial osteoarthritis and varus deformity of the knee. Lateral root tears tend to be predominantly traumatic and are frequently associated with ACL ruptures. However, in the MMRT group, a small subgroup with a traumatic etiology and in the LMRT group a small subgroup of patients with non-traumatic etiology could be identified.

LEVEL OF EVIDENCE

III.

Magnetic Resonance Imaging of Lateral Meniscus Root Tears in the Pediatric and Adolescent Knee: Is the Diagnosis Missed, Mentioned, or Made?

Background:

Failure to address meniscus root tears may place undue loads on anterior cruciate ligament (ACL) reconstructive surgery in the adult population. Because the intraoperative management of lateral meniscus posterior root tears (LMPRTs) may diverge from standard meniscal work and requires specialty items, preoperative diagnosis may be advantageous.

Purpose:

To evaluate the reliability of radiologist interpretations of preoperative knee magnetic resonance imaging (MRI) scans of lateral meniscus root pathology in a mixed pediatric and adolescent population.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

A retrospective review of medical records was performed to identify patients younger than 18 years with an arthroscopically confirmed LMPRT who underwent knee arthroscopy between March 1, 2010, and April 1, 2020. Arthroscopic findings were compared with the reading radiologist’s preoperative MRI interpretations, and patients were stratified into 2 groups: (1) LMPRT diagnosis made preoperatively or (2) diagnosis missed or only mentioned to describe pathology nonspecific to the root. Variables such as body mass index (BMI), open physes, time from injury to MRI, time from MRI to surgery, MRI magnet field strength, musculoskeletal radiologist designation, insurance type, and tear grade were assessed between groups.

Results:

Overall, 1116 knee arthroscopies were performed, with 49 LMPRTs found; all 49 LMRPTs were found concomitantly with ACL tears (49/535; 9.2%). The average patient age was 15.97 years (range, 11.52-17.97 years). There were 50 MRI scans for 49 patients. An LMPRT was diagnosed based on preoperative MRI scans in 12 of these 50 scans (24%) and mentioned or missed in 38 of the 50 scans (76%). No significant difference was seen between the diagnosis-made versus diagnosis-mentioned/missed groups in BMI, skeletal maturity, time from injury to MRI, time from MRI to surgery, MRI magnet strength, fellowship training of the reading radiologist, tear grade, or insurance type.

Conclusion:

In 76% of patients, a definitive diagnosis of LMPRT was not made on preoperative MRI scans. Notably, all LMPRTs found intraoperatively were found concomitantly with ACL tears.

Sensitivity and Specificity of MRI in Diagnosing Concomitant Meniscal Injuries With Pediatric and Adolescent Acute ACL Tears

Background:

Preoperative diagnosis of concomitant meniscal tears in pediatric and adolescent patients with acute anterior cruciate ligament (ACL) deficiency is challenging.

Purpose:

To investigate the diagnostic performance of magnetic resonance imaging (MRI) in detecting meniscal injuries for pediatric and adolescent patients with acute ACL tears.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

The authors retrospectively identified patients aged ≤18 years who underwent acute ACL reconstruction between 2006 and 2018 at 2 tertiary academic hospitals. The primary outcomes were arthroscopically confirmed medial, lateral, or any (defined as medial and/or lateral) meniscal tears. To control for chronically deficient knees, patients must have received their MRI study within 4 weeks of injury and must have undergone surgery no more than 8 weeks after their MRI study. Preoperative MRI reports were compared with the gold standard of arthroscopically confirmed tears to calculate sensitivity, specificity, positive predictive value, and negative predictive value. In a secondary analysis, patients were stratified by age into 2 groups (≤13 or ≥14 years), body mass index-for-age data from the Centers for Disease Control were used to classify patients as obese or nonobese, and differences between sensitivity and specificity proportions were analyzed using chi-square test for homogeneity.

Results:

Overall, 406 patients with a mean age of 15.4 years (range, 10-18 years) were identified. The sensitivity, specificity, positive predictive value, and negative predictive value were as follows: for lateral meniscal (LM) tears, 51.0%, 86.5%, 78.3%, and 65.0%; for medial meniscal tears, 83.2%, 80.6%, 62.3%, and 92.5%; and for any meniscal tear, 75.0%, 72.1%, 81.5%, and 63.8%, respectively. In the stratified analysis, MRI was less specific for the following diagnoses: any meniscal tear in patients aged ≤13 years (P = .048) and LM tears in obese patients (P = .020).

Conclusion:

The diagnostic ability of MRI to predict meniscal injuries present at acute ACL reconstruction was moderate. Performance was poorest at the lateral meniscus, where MRI failed to detect 97 tears that were found arthroscopically. Specificity was significantly lower in younger patients for any meniscal tear and in obese patients for LM tears.

Stay Ipsilateral: An Analysis of Tibial Tunnel Distance Between Cruciate Ligament Reconstruction and Posterior Meniscal Root Repair

Purpose

To establish mean distance or identify intersection between tibial tunnels for posterior meniscal root repair in the setting of anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) reconstruction.

Methods

Twelve cadaver knees and 12 solid foam synthetic tibiae were used. ACL and PCL tunnels were drilled for single-bundle reconstruction, and both medial and lateral posterior root repair tunnels were drilled. Specimens underwent computed tomography scanning and shortest distances between tunnels in all planes were measured by 2 readers. Distances were compared between groups using a t-test.

Results

In ACL reconstruction, the medial meniscal root tunnel was not significantly closer to the cruciate tunnel when drilled from either medial or lateral side (P = .333). The lateral meniscal root tunnel was significantly closer when drilled from medial compared to lateral side (P < .001). In PCL reconstruction, both medial (P = .037) and lateral (P = .028) meniscal root tunnels were significantly closer to the PCL tunnel when drilled from the contralateral side of the tibia.

Conclusion

This study demonstrates that posterior meniscal root repair tunnels are often placed within a few millimeters and can even intersect cruciate ligament reconstruction tunnels in the proximal tibia.

Clinical Relevance

The information in this study may assist surgeons in planning for cruciate ligament reconstruction with concomitant posterior meniscal root repair.

Lateral Meniscus Posterior Root Injury: MRI Findings in Children With Anterior Cruciate Ligament Tear

BACKGROUND. Undiagnosed and unrepaired root tears are increasingly recognized as a preventable cause of accelerated osteoarthritis. Preoperative MRI findings of lateral meniscus posterior root tears in children with concomitant anterior cruciate ligament (ACL) injury are not well described. OBJECTIVE. The purpose of this study was to investigate the performance of preoperative MRI for identifying concomitant lateral meniscus posterior root injuries in pediatric patients with ACL tears with arthroscopy as the reference standard. METHODS. Consecutively registered children who underwent MRI within 90 days before arthroscopic primary ACL reconstruction between March 2017 and December 2019 were included. Two radiologists assessed MRI examinations for direct signs involving the root proper and for findings associated with lateral meniscus posterior root tears. Kappa coefficients for MRI findings were computed. Findings in patients with root tears and intact roots were compared by independent-samples t test, Mann-Whitney U test, chi-square test, Fisher exact test, and multivariable logistic regression analysis. RESULTS. At arthroscopy, 39 children (18 boys, 21 girls; mean age, 15.2 ± 1.4 years) had lateral meniscus posterior root tears; 51 (22 boys, 29 girls; mean age, 15.7 ± 1.8 years) had intact roots. Kappa coefficients ranged from 0.65 to 0.92, aside from tears involving the entheseal segment (κ = 0.55) or popliteomeniscal fascicles (κ = 0.45). MRI findings that were predictors of arthroscopically diagnosed root tear (p < .05) were lateral meniscus root tear in any segment (odds ratio [OR], 16.8; 95% CI, 5.6-50.1), degeneration in any segment (OR, 3.9; 95% CI, 1.6-9.6), coronal cleft sign (OR, 5.7; 95% CI, 2.0-16.7), sagittal ghost sign (OR, 4.8; 95% CI, 1.2-19.1), and axial radial defect sign (OR, 7.1; 95% CI, 2.4-20.5). Tear involving any segment of the root proper had the highest PPV, 82%, with 79% NPV. The coronal cleft, sagittal ghost, and axial radial defect signs had specificities of 88%, 94%, and 88% but sensitivities of 44%, 23%, and 49%. The only significant independent predictor on preoperative MRI was root tear in any segment (OR, 15.8; 95% CI, 2.7-137.5; p = .003). CONCLUSION. Among MRI findings evaluated for preoperative diagnosis of lateral meniscus posterior root tear, tear involving any segment of the root proper had the strongest performance; associated findings had high specificity but low sensitivity. CLINICAL IMPACT. Accurate identification of lateral meniscus posterior root tears on preoperative MRI can aid in operative planning and reduce treatment delay.

High prevalence of a deep lateral femoral notch sign in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus

PURPOSE

To determine the prevalence of a deep lateral femoral notch sign (LFNS) in magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus (PLRT).

METHODS

A retrospective chart review was conducted to identify all patients undergoing ACL reconstruction between 2016 and 2018. Based on the arthroscopic appearance of the lateral meniscus, patients were assorted to one of three groups: isolated ACL tear (ACL-Group), ACL tear with concomitant lateral meniscus tear not involving the posterolateral root (Meniscus-Group), and ACL tear with concomitant PLRT (PLRT-Group). Incidence and depth of a LFNS on preoperative MRI was compared between the three cohorts.

RESULTS

115 patients (mean age: 29.5 ± 11.3 years) were included in the study, with 58 patients (50.4%) assorted to the ACL-Group, 24 patients (20.9%) to the Meniscus-Group, and 33 patients (28.7%) to the PLRT-Group. The prevalence of a LFNS was significantly higher in the PLRT-Group (39.4%), when compared to the ACL- (5.2%) or Meniscus-Groups (25.0%; p < 0.001, respectively). Additionally, logistic regression analysis demonstrated that patients with PLRT were 5.3 times more likely to have a LFNS as compared to those without a lateral root tear (p < 0.001).

CONCLUSION

In patients with ACL tears, the presence of a LFNS on preoperative MRI may be predictive for a PLRT. As the LFNS occurs in almost 40% of the patients with combined ACL tears and PLRT, the LFNS may be a useful secondary diagnostic finding in early MRI diagnostic. Identifying PLRT on MRI is clinically relevant, as it prevents misdiagnosis and facilitates surgical decision-making, thus avoiding subsequent delayed treatment.

LEVEL OF EVIDENCE

Level IV.

Vibration Stimulation as a Non-Invasive Approach to Monitor the Severity of Meniscus Tears

Musculoskeletal disorders and injuries are one of the most prevalent medical conditions across age groups. Due to a high load-bearing function, the knee is particularly susceptible to injuries such as meniscus tears. Imaging techniques are commonly used to assess meniscus injuries, though this approach suffers from limitations including high cost, need for skilled personnel, and confinement to laboratory or clinical settings. Vibration-based structural monitoring methods in the form of acoustic emission analysis and vibration stimulation have the potential to address the limits associated with current diagnostic technologies. In this study, an active vibration measurement technique is employed to investigate the presence and severity of meniscus tear in cadaver limbs. In a highly controlled ex vivo experimental design, a series of cadaver knees (n =6) were evaluated under an external vibration, and the frequency response of the joint was analyzed to differentiate the intact and affected samples. Four stages of knee integrity were considered: baseline, sham surgery, meniscus tear, and meniscectomy. Analyzing the frequency response of injured legs showed significant changes compared to the baseline and sham stages at selected frequency bandwidths. Furthermore, a qualitative analytical model of the knee was developed based on the Euler-Bernoulli beam theory representing the meniscus tear as a change in the local stiffness of the system. Similar trends in frequency response modulation were observed in the experimental results and analytical model. These findings serve as a foundation for further development of wearable devices for detection and grading of meniscus tear and for improving our understanding of the physiological effects of injuries on the vibration characteristics of the knee. Such systems can also aid in quantifying rehabilitation progress following reconstructive surgery and / or during physical therapy.

Diagnostic Accuracy of Magnetic Resonance Imaging in the Detection of Type and Location of Meniscus Tears: Comparison with Arthroscopic Findings

Magnetic resonance imaging (MRI) has been widely used for the diagnosis of meniscal tears, but its diagnostic accuracy, depending on the type and location, has not been well investigated. We aimed to evaluate the diagnostic accuracy of MRI by comparing MRI and arthroscopic findings. Preoperative 3.0-T MRI and arthroscopic findings from 2005 to 2018 were reviewed to determine the presence, type, and location of meniscus tears. In addition, subgroup analysis was performed according to anterior cruciate ligament (ACL) injury. The exclusion criteria were as follows: (1) Inflammatory arthritis, (2) other ligament injuries, (3) inability to classify meniscal tears due to degenerative arthritis, (4) over 90 days from MRI to surgery, and (5) incomplete data. Of the 2998 eligible patients, 544 were finally included. The sensitivity and specificity of MRI in determining medial and lateral meniscus tears were 91.8% and 79.9%, and 80.8% and 85.4%, respectively. The accuracy of MRI in the ACL-injured group was lower than that in the ACL-intact group (medial meniscus: 81.7% vs. 88.1%, p = 0.041; 72.9% vs. lateral meniscus: 88.0%, p < 0.001). MRI accuracy was low for the longitudinal tears of the posterior horn of the medial meniscus in the ACL-injured group. MRI could be a diagnostic tool for meniscus tears, but has limited accuracy in their classification of the type and location. Hence, care should be taken during arthroscopic assessment of ACL-injured patients due to low diagnostic accuracy of preoperative MRI.

Accuracy measures of 1.5-tesla MRI for the diagnosis of ACL, meniscus and articular knee cartilage damage and characteristics of false negative lesions: a level III prognostic study

BACKGROUND

MRI is the most accurate imaging modality for diagnosing knee pathologies. However, there is uncertainty concerning factors predicting false negative MRI, such as meniscal tear patterns as well as patient factors. The aims of this study were to report 1.5-Tesla MRI accuracy of ACL, meniscus and articular cartilage damage and characterize false negative lesions.

METHODS

Two hundred eighteen consecutive knee arthroscopies performed in our institution between 2013 and 2016 and their respective prospectively-collected MRI reports were reviewed. Inclusion criteria were age > 15 years-old, primary arthroscopy, 1.5-Tesla MRI performed at the same institution, and time interval MRI-surgery < 6 months. Exclusion criteria were revision arthroscopy and arthroscopic-assisted fracture fixation or multiligament surgery. Accuracy measures and Kappa coefficients were calculated comparing the MRI diagnosis to the arthroscopic findings. Moreover, the arthroscopic findings of false negative MRI were compared to the findings of true positive MRI using the Fisher-exact test. Pearson correlation was used for testing the correlation between MRI accuracy and patient age.

RESULTS

The highest accuracy was observed in medial meniscus and in ACL findings. For the medial meniscus sensitivity, specificity, agreement, and Kappa coefficient were 77, 92, 86%, and 0.7, and for the ACL these measures were 82, 97, 87%, and 0.73. MRI accuracy was lower in the lateral meniscus and articular cartilage with Kappa coefficient 0.42 and 0.3, respectively. More specifically, short peripheral tears in the posterior horn of the medial meniscus were characteristic of false negative findings compared to true positive findings of the MRI (p <  0.01). MRI accuracy correlated negatively compared to arthroscopic findings with patient age for the medial meniscus (r = - 0.21, p = 0.002) and for articular cartilage damage (r = - 0.45, p <  0.001).

CONCLUSION

1.5-Tesla MRI will accurately diagnose ACL and medial meniscal tears and can reliably complete the diagnostic workup following physical examination, particularly in young adults. This modality however is not reliable for diagnosing short peripheral tears at the posterior horn of the medial meniscus and partial thickness articular cartilage lesion of the femoral condyles. For these lesions, definitive diagnosis may require cartilage-specific MRI sequences or direct arthroscopic evaluation.

LEVEL OF EVIDENCE

Prognostic study, Level III.

Efficacy of Arthroscopic Treatment for Concurrent Medial Meniscus Posterior Horn and Lateral Meniscus Anterior Horn Injury: A Retrospective Single Center Study

Objective

To investigate the effectiveness of arthroscopic surgery for combined tears of the posterior horn of the medial meniscus (PHMM) and the anterior horn of the lateral meniscus (AHLM).

Methods

Between September 2009 and December 2013, a retrospective investigation was performed on 48 patients (48 knees) with combined tears of PHMM and AHLM who underwent arthroscopic surgery. All patients underwent magnetic resonance imaging (MRI) diagnosis in the outpatient department. After admission, other basic examinations were performed. PHMM was treated with partial meniscectomy and AHLM was treated with external–internal suture or partial meniscectomy. Curative effect was evaluated according to Lysholm score and IKDC score. The differences of the functions as well as Lysholm and IKDC scores pre‐ and postoperatively were compared, while the diagnostic accuracy of MRI and arthroscopy for PHMM and AHLM were compared.

Results

Seven patients with combined tears of PHMM and AHLM were misdiagnosed during MRI examination when arthroscopy was used as the gold standard. All patients were followed up for an average of 34.58 months (range 10–52 months) and all incisions healed by first intention with no obvious complication. The preoperative and postoperative Lysholm scores were 47.22 ± 2.77 and 87.36 ± 5.45, respectively. The IKDC scores are 54.73 ± 4.65 preoperatively and 89.62 ± 3.71 postoperatively. The positive rates of the diagnosis through MRI and arthroscopic surgery is 85.42% and 100%, respectively. At the last follow‐up, the patients had no pain, weakness, and instability, and tenderness in medial and lateral joint space disappeared. Mcmurray test was weakly positive in four patients. Excellent outcome was achieved in 39 cases, and a good outcome was achieved in five cases; the good to excellent rate was 91.67%.

Conclusion

MRI examination of combined tears of PHMM and AHLM may result in misdiagnosis. Arthroscopic primary repair seemed to be an effective surgical option for treatment of combined tears of PHMM and AHLM.

Injury of the Meniscus Root

Meniscus root tears biomechanically disrupt normal joint loading and lead to joint overload with the possible development of spontaneous osteonecrosis of the knee and early-onset osteoarthritis. Proper identification and treatment of meniscal root tears has been proven to restore joint loading and improve patient outcomes.

Functional MRI Mapping of Human Meniscus Functionality and its Relation to Degeneration

Meniscus pathology may promote early osteoarthritis. This study assessed human meniscus functionality (i.e. its response to loading) ex vivo based on quantitative T1, T1ρ, and T2 mapping as a function of histological degeneration and loading. Forty-five meniscus samples of variable degeneration were harvested from the lateral meniscus body region of 45 patients during total knee arthroplasties. Samples underwent serial mapping on a 3.0-T MRI scanner (Achieva, Philips) using a force-controlled and torque-inducing compressive loading device. Samples were measured at three loading positions, i.e. unloaded, loaded to 2 bar (compression force 37 N) and 4 bar (69 N). Histology (Pauli classification) and biomechanics (Elastic Modulus) served as references. Based on histology, samples were trichotomized as grossly intact (n = 14), mildly degenerative (n = 16), and moderate-to-severely degenerative (n = 15) and analyzed using appropriate parametric and non-parametric tests. For T1, we found loading-induced decreases in all samples, irrespective of degeneration. For T1ρ, zonal increases in intact (apex) and decreases in degenerative samples (base) were found, while for T2, changes were ambiguous. In conclusion, force-controlled loading and serial MR imaging reveal response-to-loading patterns in meniscus. Zonal T1ρ response-to-loading patterns are most promising in differentiating degeneration, while T1 and T2 aren’t clearly related to degeneration.and may provide an imaging-based indication of functional tissue properties.

Prevalence of abnormal findings in 230 knees of asymptomatic adults using 3.0 T MRI

OBJECTIVE

To identify abnormalities in asymptomatic sedentary individuals using 3.0 Tesla high-resolution MRI.

MATERIALS AND METHODS

The cohort comprised of 230 knees of 115 uninjured sedentary adults (51 males, 64 females; median age: 44 years). All participants had bilateral knee 3.0 T MRIs. Two senior musculoskeletal radiologists graded all intraarticular knee structures using validated scoring systems. Participants completed Knee Injury and Osteoarthritis Outcome Score questionnaires at the time of the MRI scan.

RESULTS

MRI showed abnormalities in the majority (97%) of knees. Thirty percent knees had meniscal tears: horizontal (23%), complex (3%), vertical (2%), radial (2%) and bucket handle (1%). Cartilage and bone marrow abnormalities were prevalent at the patellofemoral joint (57% knees and 48% knees, respectively). Moderate and severe cartilage lesions were common, in 19% and 31% knees, respectively, while moderate and severe bone marrow oedema in 19% and 31% knees, respectively. Moderate-intensity lesion in tendons was found in 21% knees and high-grade tendonitis in 6% knees-the patellar (11% and 2%, respectively) and quadriceps (7% and 2%, respectively) tendons being most affected. Three percent partial ligamentous ruptures were found, especially of the anterior cruciate ligament (2%).

CONCLUSION

Nearly all knees of asymptomatic adults showed abnormalities in at least one knee structure on MRI. Meniscal tears, cartilage and bone marrow lesions of the patellofemoral joint were the most common pathological findings. Bucket handle and complex meniscal tears were reported for the first time in asymptomatic knees.

Cost-Effectiveness Analysis of Needle Arthroscopy Versus Magnetic Resonance Imaging in the Diagnosis and Treatment of Meniscal Tears of the Knee

PURPOSE

To determine whether needle arthroscopy (NA) compared with magnetic resonance imaging (MRI) in the diagnosis and treatment of meniscal tears is cost-effective when evaluated over a 2-year period via patient-reported outcomes. The hypothesis is that improved diagnostic accuracy with NA would lead to less costly care and similar outcomes.

METHODS

A Markov model/decision tree analysis was performed using TreeAge Pro 2017 software. Patients were evaluated for degenerative and traumatic damage to the lateral/medial meniscus. Assumed sensitivities and specificities were derived from the medical literature. The direct costs for care were derived from the 2017 Medicare fee schedule and from private payer reimbursement rates. Costs for care included procedures performed for false-positive findings and for care for false-negative findings. Effectiveness was examined using the global knee injury and osteoarthritis outcome score (KOOS). Patients were evaluated over 2 years for costs and outcomes, including complications. Dominance and incremental cost-effectiveness were evaluated, and 1- to 2-way sensitivity analysis was performed to determine those variables that had the greatest effect. The consolidated economics evaluation and reporting standards checklist for reporting economic evaluations was used.

RESULTS

NA was less costly and had similar KOOS versus MRI for both the medial/lateral meniscus with private pay. Costs were less for both Medicare and private pay for medial meniscus, $780 to $1,862, and lateral meniscus, $314 to $1,256, respectively.

CONCLUSIONS

Based on the reported MRI incidence of false positives with the medial meniscus and false negatives with the lateral meniscus and based on assumed standards of care, more costly care is provided when using MRI compared with NA. Outcomes were similar with NA compared with MRI.

LEVEL OF EVIDENCE

Level II, economic and decision analysis.

Lateral meniscus posterior root tear contributes to anterolateral rotational instability and meniscus extrusion in anterior cruciate ligament-injured patients

PURPOSE

The purposes of this study were to investigate (1) meniscus status and clinical findings in anterior cruciate ligament (ACL)-injured patients to clarify associations between the meniscus posterior root tear (PRT) and knee instability, and (2) magnetic resonance imaging (MRI) findings of the PRT to clarify sensitivity and specificity of MRI and prevalence of meniscus extrusion.

METHODS

Three hundred and seventeen patients with primary ACL reconstruction were included. PRTs for both medial and lateral sides were confirmed by reviewing surgical records. Preoperative MRI was reviewed to evaluate sensitivity and specificity of the PRT and meniscus extrusion width (MEW). Clinical information regarding the number of giving-way episodes, preoperative KT-1000 measurements and preoperative pivot shift was also assessed.

RESULTS

Thirty-nine patients had a lateral meniscus (LM) PRT, whereas only four patients had a medial meniscus PRT. One hundred and seventeen patients had no meniscus tear (control). Twenty-eight patients (71.8%) showed positive signs of the LMPRT based on at least one view of MR images, with the coronal view showing the highest sensitivity. MEW in the LMPRT group was significantly larger than that in the control group. The preoperative pivot shift test grade in the LMPRT group was significantly greater than that in the control group. There were no significant differences in other parameters.

CONCLUSIONS

In ACL-injured patients, the LMPRT was associated with ALRI as well as with meniscus extrusion. The coronal view of MRI was useful in identifying the LMPRT, although its sensitivity was not high. Therefore, surgeons should prepare to repair PRTs at the time of ACL reconstruction regardless of MRI findings, and they should make every effort to repair the LMPRT.

LEVEL OF EVIDENCE

III.

Both Posterior Root Lateral-Medial Meniscus Tears With Anterior Cruciate Ligament Rupture: The Step-by-Step Systematic Arthroscopic Repair Technique

The occurrence of posterior root tear of both the lateral and medial menisci, combined with anterior cruciate ligament rupture, is rare. Problems may be encountered such as the difficulty to access the medial meniscal root tear, the confusing circumstances about which structure to repair first, and the possibility of the tunnel for each repair to become taut inside the tibial bone. We present the arthroscopy technique step by step to overcome the difficulties in an efficient and time-preserving manner.

Correlation of parameters on preoperative CT images with intra-articular soft-tissue injuries in acute tibial plateau fractures: A review of 132 patients receiving ARIF

INTRODUCTION

Tibial plateau fractures often occur in conjunction with soft-tissue injuries of knees. The hypothesis of this study is that parameters of CT imaging can predict intra-articular soft-tissue injuries.

PATIENTS AND METHODS

Patients who underwent arthroscopically assisted reduction and internal fixation (ARIF) for acute tibial plateau fractures performed by a single orthopedic surgeon between 2005 and 2015 were included in this retrospective study. Patients with concomitant ipsilateral femoral fractures, who had received revision surgery or who had undergone index surgery more than 30days from the event were excluded. We measured lateral plateau depression and widening, medial plateau depression and displacement, and column involvement observed on preoperative CT scans. Intra-articular soft-tissue injuries were diagnosed based on findings from knee arthroscopy. The correlation of imaging parameters with soft-tissue injuries was analyzed by the area under a receiver operating characteristic (AUROC) curve and multivariate logistic regression.

RESULTS

One-hundred and thirty-two patients were enrolled in the study. The average age was 45.7±13.1 years (range: 18-75 years). Lateral tibial plateau depressions >11mm were significantly associated with increased risk of lateral meniscus tears (p=0.001). However, there was no significant threshold of lateral tibial plateau widening that could be used to predict lateral meniscus tear. Greater risk of anterior cruciate ligament (ACL) avulsion fracture was observed in younger patients, patients with high-energy-pattern tibial plateau fractures, patients with fractures involving anteromedial or posterolateral columns, and patients with medial tibial plateau displacement >3mm (p<0.05).

CONCLUSION

Measuring lateral tibial plateau depression and column involvement on preoperative CT scans can help predict a higher risk of lateral meniscus tear and ACL avulsion fracture respectively in patients with acute tibial plateau fractures.

Ex vivo quantitative multiparametric MRI mapping of human meniscus degeneration

OBJECTIVES

To evaluate the diagnostic performance of T1, T1ρ, T2, T2*, and UTE-T2* (ultrashort-echo time-enhanced T2*) mapping in the refined graduation of human meniscus degeneration with histology serving as standard-of-reference.

MATERIALS AND METHODS

This IRB-approved intra-individual comparative ex vivo study was performed on 24 lateral meniscus body samples obtained from 24 patients undergoing total knee replacement. Samples were assessed on a 3.0-T MRI scanner using inversion-recovery (T1), spin-lock multi-gradient-echo (T1ρ), multi-spin-echo (T2) and multi-gradient-echo (T2* and UTE-T2*) sequences to determine relaxation times of quantitative MRI (qMRI) parameters. Relaxation times were calculated on the respective maps, averaged to the entire meniscus and to its zones. Histologically, samples were analyzed on a four-point score according to Williams (0-III). QMRI results and Williams (sub)scores were correlated using Spearman's ρ, while Williams grade-dependent differences were assessed using Kruskal-Wallis and Dunn's tests. Sensitivities and specificities in the detection of intact (Williams grade [WG]-0) and severely degenerate meniscus (WG-II-III) were calculated.

RESULTS

Except for T2*, significant increases in qMRI parameters with increasing Williams grades were observed. T1, T1ρ, T2, and UTE-T2* exhibited high sensitivity and variable specificity rates. Significant marked-to-strong correlations were observed for these parameters with each other, with histological WGs and the subscores tissue integrity and cellularity.

CONCLUSIONS

QMRI mapping holds promise in the objective evaluation of human meniscus. Although sufficient discriminatory power of T1, T1ρ, T2, and UTE-T2* was only demonstrated for the histological extremes, these data may aid in the future MRI-based parameterization and quantification of human meniscus degeneration.

Comparison of clinical, MRI and arthroscopic assessments of chronic ACL injuries, meniscal tears and cartilage defects

PURPOSE

The aim of this study was to compare the accuracy of clinical examination to that of MRI evaluated by two independent radiologists for the diagnosis of meniscal tears and chronic anterior cruciate ligament injuries and to assess the MRI accuracy in the diagnosis of cartilage defects.

METHODS

Seventy-six consecutive patients with suspected intra-articular knee pathology were prospectively evaluated by objective examination, 1.5 T MRI, re-examined by trained radiologist and arthroscopy. Accuracy, sensitivity, specificity, positive predictive value and negative predictive value were calculated. Agreement analysis with kappa (К) coefficient values was performed for meniscal and ACL tears.

RESULTS

No differences were found between diagnostic accuracy of clinical examination, the first and second MRI reports in diagnosis of medial meniscus (84 vs 96 vs 97 %) and anterior cruciate ligament injuries (93 vs 78 vs 89 %). For the lateral meniscal tears, the accuracy of the second radiologist was significantly higher than those of the first (96 vs 75 %; p < 0.01) and clinical examination (96 vs 86 %; p = 0.02). High diagnostic values were obtained for the diagnosis of full-thickness chondral defects with sensitivity of 100 %, specificity of 95 % and accuracy of 95 %.

CONCLUSION

Clinical and MRI evaluations have no differences in the diagnosis of medial meniscus and anterior cruciate ligament injuries. A trained radiologist obtained better sensitivity, specificity and accuracy in the diagnosis of lateral meniscus. 1.5 T MRI does not represent the technique of choice in the evaluation of chondral defect but demonstrated high diagnostic accuracy for detection of full-thickness chondral defects.

LEVEL OF EVIDENCE

Diagnostic prospective study, Level II.

Posterior meniscal root injuries

- Meniscal root tears (MRTs) are defined as radial tears within 1 cm of the meniscal root insertion, or an avulsion of the insertion of the meniscus. These injuries change joint loading due to failure of the meniscus to convert axial loads into hoop stresses, resulting in joint overloading and degenerative changes in the knee. Meniscal root repair is recommended in patients without advanced osteoarthritis (Outerbridge 3-4), in order to restore joint congruence and loading and therefore to avoid the long-term effect of joint overloading. Several techniques have been described. Improved knee function has been reported after meniscal root repair, but there are still conflicting reports on whether surgical treatment can prevent osteoarthritis.

Accuracy of MRI evaluation of meniscus tears in the setting of ACL injuries

BACKGROUND

Our purpose was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) for the pre-operative detection of meniscus tears requiring operative intervention, and identify factors that determined accuracy of diagnosing meniscus tears, in the setting of anterior cruciate ligament (ACL) reconstruction.

METHODS

Patients who underwent primary ACL reconstruction were retrospectively reviewed. A meniscus tear was classified as requiring treatment if it was debrided or repaired at the time of ACL reconstruction. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of pre-operative MRIs were determined for medial and lateral meniscus tears.

RESULTS

Sensitivity, specificity, PPV, and NPV of MRI were 0.90, 0.75, 0.58, and 0.95 for medial meniscus tears, respectively, and 0.67, 0.81, 0.65, and 0.82 for lateral meniscus tears. MRI-diagnosed medial meniscus tears were associated with a longer time interval between initial injury and imaging compared to ACL tears without concomitant meniscus injury on MRI (p=0.038). Vertical medial meniscus tears were less likely than other tear patterns to require treatment at the time of ACL reconstruction (p=0.03). MRI showed a higher diagnostic performance for lateral meniscus tears when surgery was performed within 30days of imaging.

CONCLUSIONS

This study demonstrates only moderate sensitivity and specificity of pre-operative MRI in the detection of meniscus tears requiring operative treatment in the setting of ACL injury. High rates of false diagnoses were observed, suggesting MRI may not be as accurate in predicting positive or negative meniscus findings at the time of ACL reconstruction as previously reported.

LEVEL OF EVIDENCE

Level III.

Diagnosis of ligamentous and meniscal pathologies in patients with anterior cruciate ligament injury: comparison of magnetic resonance imaging and arthroscopic findings

BACKGROUND

Magnetic resonance imaging (MRI) is routinely used to diagnose or support clinical diagnoses for meniscal or ligamentous injuries prior to offering patients arthroscopic treatment. However, the sensitivity of MRI for the detection of meniscal injury is not yet 100%. Sportsmen have occasionally returned to play with undiagnosed meniscal lesions on the basis of a normal MRI examination. This study was designed to assess the diagnostic parameters of MRI in patients with acute anterior cruciate ligament (ACL) injury.

METHODS

MRI and arthroscopic findings of 320 patients with acute ACL injury were included in this retrospective review. Patients belonged to a single surgeon from a high volume tertiary healthcare institution. All patients had either a MRI or an arthroscopic diagnosis of an acute ACL injury of one knee or both. All patients underwent therapeutic arthroscopy by the senior author routinely as part of arthroscopy-aided ACL reconstruction. Arthroscopic findings were the diagnostic reference based on which the positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and concordance strength of association of MRI were calculated for ACL, posterior cruciate ligament (PCL), medial meniscus (MM) and lateral meniscus (LM) injuries.

RESULTS

MRI was most accurate in diagnosing cruciate ligament injuries with a PPV approaching 100%. The PPV of MRI in diagnosing meniscal injuries was approximately 60%. MRI was almost 100% sensitive and specific in diagnosing ACL injuries and 82% sensitive and 100% specific in diagnosing PCL injuries. Conversely, MRI was 77% sensitive and 90% specific in diagnosing MM injuries; and 57% sensitive and 95% specific in diagnosing LM injuries.

CONCLUSIONS

MRI remains the gold standard for diagnosing soft tissue injuries of the knee. However, there is a false positive rate ranging from 6% to 11% for meniscal tears.

MR imaging-based diagnosis and classification of meniscal tears

Magnetic resonance (MR) imaging is currently the modality of choice for detecting meniscal injuries and planning subsequent treatment. A thorough understanding of the imaging protocols, normal meniscal anatomy, surrounding anatomic structures, and anatomic variants and pitfalls is critical to ensure diagnostic accuracy and prevent unnecessary surgery. High-spatial-resolution imaging of the meniscus can be performed using fast spin-echo and three-dimensional MR imaging sequences. Normal anatomic structures that can mimic a tear include the meniscal ligament, meniscofemoral ligaments, popliteomeniscal fascicles, and meniscomeniscal ligament. Anatomic variants and pitfalls that can mimic a tear include discoid meniscus, meniscal flounce, a meniscal ossicle, and chondrocalcinosis. When a meniscal tear is identified, accurate description and classification of the tear pattern can guide the referring clinician in patient education and surgical planning. For example, longitudinal tears are often amenable to repair, whereas horizontal and radial tears may require partial meniscectomy. Tear patterns include horizontal, longitudinal, radial, root, complex, displaced, and bucket-handle tears. Occasionally, meniscal tears can be difficult to detect at imaging; however, secondary indirect signs, such as a parameniscal cyst, meniscal extrusion, or linear subchondral bone marrow edema, should increase the radiologist's suspicion for an underlying tear. Awareness of common diagnostic errors can ensure accurate diagnosis of meniscal tears. Online supplemental material is available for this article.

Comparison of Medial and Lateral Meniscus Root Tears

The meniscus root plays an essential role in maintaining the circumferential hoop tension and preventing meniscal displacement. Studies on meniscus root tears have investigated the relationship of osteoarthritis and an anterior cruciate ligament tear. However, few studies have directly compared the medial and lateral root tears. To assess the prevalence of meniscal extrusion and its relationship with clinical features in medial and lateral meniscus root tears, we performed a retrospective review of the magnetic resonance imaging (MRI) results of 42 knee patients who had meniscus posterior horn root tears and who had undergone arthroscopic operations. The presence of meniscal extrusion was evaluated and the exact extent was measured from the tibial margin. The results were correlated with arthroscopic findings. Clinical features including patients’ ages, joint abnormalities, and previous trauma histories were evaluated. Twenty-two patients had medial meniscus root tears (MMRTs) and twenty patients had lateral meniscus root tears (LMRTs). Meniscal extrusion was present in 18 MMRT patients and one LMRT patient. The mean extent of extrusion was 4.2mm (range, 0.6 to 7.8) in the MMRT group and 0.9mm (range, -1.9 to 3.4) in the LMRT group. Five patients with MMRT had a history of trauma, while 19 patients with LMRT had a history of trauma. Three patients with MMRT had anterior cruciate ligament (ACL) tears, while 19 patients with LMRT had ACL tears. The mean age of the patients was 52 years (range: 29–71 years) and 30 years (range: 14–62 years) in the MMRT and LMRT group, respectively. There was a significant correlation between a MMRT and meniscal extrusion (p<0.0001), and between an ACL tear and LMRT (p<0.0001). A history of trauma was significantly common in LMRT (p<0.0001). LMRT patients were significantly younger than MMRT patients (p<0.0001). Kellgren-Lawrence (K-L) grade differed significantly between MMRT and LMRT group (p<0.0001). Meniscal extrusion is common in patients with MMRTs. However, it is rare in patients with LMRTs, which are more commonly associated with a history of trauma and ACL tears.

Quantitative MRI analysis of menisci using biexponential T2* fitting with a variable echo time sequence

PURPOSE

The goal of this study was to differentiate between normal, degenerative meniscus, and meniscal tears using monoexponentially and biexponentially calculated T2*. Meniscal disease, characterized by an altered collagen fiber matrix, might be detectable in vivo using quantitative T2* mapping.

METHODS

A 3D Cartesian spoiled gradient echo technique was adapted to enable the use of a variable echo time approach in combination with a highly asymmetric readout. T2* was calculated monoexponentially and biexponentially using three- and five-parametric non-linear fits, respectively.

RESULTS

From a total of 68 evaluated menisci, 48 were normal, 12 were degenerated, and eight had tears. Mean values for the short (T2*s) and long (T2*l) T2* components were as follows: in normal menisci, 0.82 ± 0.38/15.0 ± 5.4 ms, respectively; in degenerated menisci, 1.29 ± 0.53/19.97 ± 5.59 ms, respectively; and, in meniscal tears, 2.05 ± 0.73 and 26.83 ± 7.72 ms, respectively. Biexponentially fitted T2* demonstrated a greater ability to distinguish normal and degenerated menisci using receiver operating characteristic (ROC) analysis (higher area under curve as well as higher specificity and sensitivity).

CONCLUSION

This study suggests that biexponential fitting, used for T2* calculation in the menisci, provides better results compared to monoexponential fitting. Observed changes in T2* result from the matrix reorganization in degenerative processes in the menisci, which affects the collagen fiber orientation, as well as content.

Posterior meniscus root tears: associated pathologies to assist as diagnostic tools

PURPOSE

The purpose of this study was to investigate associated pathologies identified at arthroscopy in patients with meniscus root tears.

METHODS

This study was Institutional Review Board approved. All patients who underwent arthroscopic knee surgery where a complete meniscus root tear was identified were included in this study. Concurrent ligament tears and articular cartilage changes ≥Outerbridge grade 2 were recorded and stored in a data registry.

RESULTS

Fifty patients (28 males, 22 females) [mean age = 36.5 years (range 17.1-68.1 years)] who were diagnosed with a medial or lateral meniscus root tear at arthroscopy were included in this study out of 673 arthroscopic surgeries (prevalence 7.4 %). Twenty-three (46 %) patients had a medial meniscus root tear, 26 (52 %) patients had a lateral meniscus root tear and one (2 %) patient had both. Thirty-four per cent of patients (n = 17) underwent partial meniscectomy, while 60 % (n = 31) underwent suture repair. During arthroscopy, 60 % (n = 30) of patients were diagnosed with an anterior cruciate ligament (ACL) tear. Patients with lateral meniscus root tears were 10.3 times (95 % CI 2.6-42.5) more likely to have ACL tears than patients with medial meniscus root tears (p = 0.012). Patients who had medial meniscus root tears were 5.8 times (95 % CI 1.6-20.5) more likely to have chondral defects than patients who had lateral meniscus root tears (p = 0.044).

CONCLUSION

In this study, patients' preoperative functional scores and activity levels were low. Patients with lateral meniscal root tears were more likely to have an ACL tear. Patients with medial meniscal root tears were more likely to have an knee articular cartilage defect with an Outerbridge grade 2 or higher chondral defect. This study confirms the importance of comprehensive assessment of concurrent injuries to properly diagnose meniscus root tears.

LEVEL OF EVIDENCE

IV.

Accuracy of MRI in the diagnosis of meniscal tears in patients with chronic ACL tears

PURPOSE

This study was conducted to evaluate the accuracy of magnetic resonance imaging (MRI) in diagnosing meniscal tears in patients with anterior cruciate ligament (ACL) tears and to determine the frequency of missed meniscal tears on MRI.

METHODS

This prospective comparative study was conducted from 2009 to 2012. Patients with ACL injuries who underwent knee arthroscopy and MRI were included in the study. Two radiologists who were blinded to the clinical history and arthroscopic findings reviewed the pre-arthroscopic MR images. The presence and type of meniscal tears on MRI and arthroscopy were recorded. Arthroscopic findings were used as the reference standard. The accuracy, sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of MRI in the evaluation of meniscal tears were calculated.

RESULTS

A total of 65 patients (66 knees) were included. The sensitivity, specificity, accuracy, PPV, and NPV for the MRI diagnosis of lateral meniscal tears in our patients were 83, 97, 92, 96, and 90 %, respectively, whereas those for medial meniscus tears were 82, 92, 88, 82, and 88 %, respectively. There were five false-negative diagnoses of medial meniscus tears and four false-negative diagnoses of lateral meniscus tears. The majority of missed meniscus tears on MRI affected the peripheral posterior horns.

CONCLUSION

The sensitivity for diagnosing a meniscal tear was significantly higher when the tear involved more than one-third of the meniscus or the anterior horn. The sensitivity was significantly lower for tears located in the posterior horn and for vertically oriented tears. Therefore, special attention should be given to the peripheral posterior horns of the meniscus, which are common sites of injury that could be easily missed on MRI. The high NPVs obtained in this study suggest that MRI is a valuable tool prior to arthroscopy.

Diagnostic performance of magnetic resonance imaging and pre-surgical evaluation in the assessment of traumatic intra-articular knee disorders in children and adolescents: what conditions still pose diagnostic challenges?

BACKGROUND

Diagnosis of intra-articular lesions in children based on clinical examination and MRI is particularly challenging.

OBJECTIVE

To evaluate the diagnostic performance of MRI and pre-surgical evaluation of the knee in pediatric patients relative to arthroscopic evaluation as the gold standard. We report diagnoses frequently missed or inaccurately diagnosed pre-operatively.

MATERIALS AND METHODS

We conducted a retrospective review of MRI and pre-surgical evaluation in children and adolescents ages 1-17 years who were treated by knee arthroscopy during a 2½-year period. All MRIs were reviewed by a pediatric radiologist blinded to clinical findings. Pediatric orthopedic clinic notes were reviewed for pre-surgical evaluation (based on physical exam, radiograph, MR images and radiologist's MRI report). Arthroscopic findings were used as the gold standard. We calculated the percentages of diagnoses at arthroscopy missed on both MRI and pre-surgical evaluation. Diagnostic accuracy between children and adolescents and in patients with one pathological lesion vs. those with >1 lesion was analyzed. We performed a second review of MR images of the missed or over-called MRI diagnoses with knowledge of arthroscopic findings.

RESULTS

We included 178 children and adolescents. The most common diagnoses missed on MRI or pre-surgical evaluation but found at arthroscopy were: discoid meniscus (8/30, or 26.7% of cases); lateral meniscal tears (15/80, or 18.8% of cases); intra-articular loose bodies (5/36, or 13.9% of cases), and osteochondral injuries (9/73, or 12.3% of cases). Overall diagnostic accuracy of MRI and pre-surgical evaluation was 92.7% and 95.3%, respectively. No significant difference in diagnostic accuracy between children and adolescents was observed. When multiple intra-articular lesions were present, lateral meniscal tears were more likely to be inaccurately diagnosed (missed or over-called) on both MRI (P = 0.009) and pre-surgical evaluation (P < 0.001).

CONCLUSION

Overall diagnostic accuracy of MRI and pre-surgical evaluation was quite high. The traumatic intra-articular knee lesions that still pose a diagnostic challenge for MRI and pre-surgical evaluation are lateral discoid meniscus, lateral meniscal tears, intra-articular loose bodies and osteochondral injuries. Special attention should be given to those diagnoses when evaluating a pediatric knee MRI. In children with multiple intra-articular injuries, there is significantly more inaccuracy in pre-arthroscopic diagnosis of lateral meniscal tears on both MRI and pre-surgical evaluation.

Risk factors for posterior lateral meniscus root tears in anterior cruciate ligament injuries

PURPOSE

To identify risk factors for posterior lateral meniscus root tears (PLRT) in patients with a tear of the anterior cruciate ligament (ACL).

METHODS

A database of 268 patients undergoing primary ACL reconstruction between 2011 and 2013 was used to identify all patients with isolated ACL tears and patients with an associated PLRT. Patients with other concomitant injuries and patients who underwent surgery >6 months after the injury were excluded. Univariate analysis was performed by comparing the two groups with regard to gender, age, age groups (<30 vs. >30 years), height, weight, body mass index (BMI), BMI groups (<24.9, 25-29.9, and >30), type of injury (high-impact sports, low-impact sports, and not sports-related), and mechanism of injury (non-contact vs. contact). Multivariate logistic regression was carried out to identify independent risk factors for PLRT and to calculate odds ratios (ORs).

RESULTS

One-hundred and forty-two patients met the inclusion and exclusion criteria. Of those, 120 (85%) had an isolated ACL tear and 22 (15%) had an associated PLRT. No significant differences between patients with and without a PLRT were found for age, age groups, height, weight, BMI, BMI groups, and type of injury (p > 0.05). Univariate analysis revealed a statistically significant difference between both groups for gender distribution (p = 0.034) and mechanism of injury (p < 0.001), with male gender and a contact mechanism being more common in patients with PLRT. The sole independent risk factor for an associated PLRT identified in the multivariate logistic regression analysis was a contact mechanism with an OR of 17.52.

CONCLUSION

An associated PLRT is more common in male patients and patients who sustained a contact injury. Patients with a contact injury mechanism have an approximately 17-fold increased risk for a PLRT compared to patients with a non-contact injury. Special attention for this injury pattern is therefore necessary in those patients, and early referral to magnetic resonance imaging or arthroscopy is recommended.

LEVEL OF EVIDENCE

IV.

Diagnostic accuracy of an iPhone DICOM viewer for the interpretation of magnetic resonance imaging of the knee

OBJECTIVE

To evaluate the diagnostic performance of viewing magnetic resonance (MR) images on a handheld mobile device compared with a conventional radiology workstation for the diagnosis of intra-articular knee pathology.

DESIGN

Prospective comparison study.

SETTING

Tertiary care center.

PATIENTS

Fifty consecutive subjects who had MR imaging of the knee followed by knee arthroscopy were prospectively evaluated.

INTERVENTIONS

Two musculoskeletal radiologists independently reviewed each MR study using 2 different viewers: the OsiriX DICOM viewer software on an Apple iPhone 3GS device and eFilm Workstation software on a conventional picture archiving and communications system workstation.

MAIN OUTCOME MEASURES

Sensitivity and specificity of the iPhone and workstation interpretations was performed using knee arthroscopy as the reference standard. Intraobserver concordance and agreement between the iPhone and workstation interpretations were determined.

RESULTS

There was no statistically significant difference between the 2 devices for each paired comparison of diagnostic performance. For the iPhone interpretations, sensitivity ranged from 77% (13 of 17) for the lateral meniscus to 100% (17 of 17) for the anterior cruciate ligament. Specificity ranged from 74% (14 of 19) for cartilage to 100% (50 of 50) for the posterior cruciate ligament. There was a very high level of interobserver and intraobserver agreement between devices and readers. The iPhone reads took longer than the corresponding workstation reads, with a significant mean difference between the iPhone and workstation reads of 3.98 minutes (P < 0.001).

CONCLUSIONS

The diagnostic performance of interpreting MR images on a handheld mobile device for the assessment of intra-articular knee pathology is similar to that of a conventional radiology workstation, however, requires a longer viewing time.

CLINICAL RELEVANCE

Timely and accurate interpretation of complex medical images using mobile device solutions could result in new workflow efficiencies and ultimately improve patient care.

Meniscal injury after adolescent anterior cruciate ligament injury: how long are patients at risk?

BACKGROUND

Delay of as much as 5 months between ACL injury and surgery is known to be associated with increased risk of a medial meniscal tear, but the risk of additional meniscal tear progression with a longer delay to surgery is unclear.

QUESTIONS/PURPOSES

We determined the (1) times of injury, MRI, and surgery in adolescents with ACL tears, and whether (2) timing of surgery, or (3) initial integrity of the meniscus seen on MR images predicted development of meniscal tears.

METHODS

We reviewed 112 adolescents who were 15 ± 1 years old (mean ± SD) (range, 11-16 years) with a torn ACL. These patients underwent surgical repair from 2005 to 2011 in a Canadian city. We compared dates of injury, MRI, and surgery. A pediatric and musculoskeletal fellowship-trained radiologist reread the MR images, and meniscal injuries were graded according to severity. This was compared with surgical findings described in the operative report.

RESULTS

Time after injury to MRI and surgery averaged 77 days (range, 1-377 days) and 342 days (range, 42-1637 days), respectively. Patients with new or worsened medial meniscal tears had waited longer for surgery (445 versus 290 days; p = 0.002). Bucket handle medial meniscal tears were more common in patients with surgery more than 1 year after injury than others (15 of 34 versus 14 of 75; p = 0.013). A medial meniscal tear observed on MR images was a significant covariate for a torn meniscus at surgery (relative risk, 5.7; 95% CI, 2.8-11.6). Medial meniscal survival continued to decline sharply greater than 1 year after injury.

CONCLUSIONS

Medial meniscal tears, especially bucket handle tears, increased steadily in frequency more than 1 year after ACL injury. Timely ACL reconstruction may be warranted to reduce the risk of further medial meniscal damage even in patients whose original injury occurred more than 1 year before.

LEVEL OF EVIDENCE

Level IV, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.

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.

Parameniscal cyst formation in the knee is associated with meniscal tear size: an MRI study

BACKGROUND

The relationship between meniscal tears and parameniscal cyst formation is contentious. We investigated whether the development of a parameniscal cyst is related to the size of the meniscal tear by using magnetic resonance imaging (MRI).

METHODS

On the basis of a retrospective review of an MRI database, we identified parameniscal cysts in 34 patients with adjacent meniscal tears extending to the meniscocapsular junction. The size of the meniscal tear was measured by dividing the length of the tear along two axes: circumferential and radial. We compared parameters, such as the size of the meniscal tear, the location of the tear, the pattern of each tear, and any associated ligamentous injury and intra-articular lesion, between the 34 patients and the 30 control patients who only had meniscal tears with torn components extending to the meniscocapsular junction.

RESULTS

Compared with the controls, patients with parameniscal cysts had significantly larger meniscal tears along the circumferential axis (P<0.001). A critical size of the meniscal tear along the circumferential axis of 12mm was associated with the formation of a parameniscal cyst.

CONCLUSIONS

A larger meniscal tear extending into the meniscocapsular junction is more likely to be associated with the occurrence of a parameniscal cyst. The critical size of the meniscal tear, 12mm along the circumferential axis as identified using MRI, is a discrimination value for parameniscal cyst formation.

LEVEL OF EVIDENCE

Level III.

Magnetic resonance imaging and arthroscopic appearance of the menisci of the knee

The menisci are critical for normal function of the knee, providing shock absorption and load transmission that reduce stress on the articular cartilage. When torn, a meniscus may require surgery to restore function, reduce pain, and eliminate mechanical symptoms. Patterns of meniscal tears include longitudinal and bucket-handle, which are often reparable; and horizontal, radial, vertical flap, horizontal flap, and complex. Root tears are usually radial and occur in the posterior roots. When reviewing magnetic resonance images, one must be aware of normal variants and imaging pitfalls that may simulate pathology.

Spectrum of injuries associated with paediatric ACL tears: an MRI pictorial review

OBJECTIVE

Magnetic resonance imaging (MRI) findings in anterior cruciate ligament (ACL) injury are well known, but most published reviews show obvious examples of associated injuries and give little focus to paediatric patients. Here, we demonstrate the spectrum of MRI appearances at common sites of associated injury in adolescents with ACL tears, emphasising age-specific issues.

METHODS

Pictorial review using images from children with surgically confirmed ACL tears after athletic injury.

RESULTS

ACL injury usually occurs with axial rotation in the valgus near full extension. The MRI findings can be obvious and important to management (ACL rupture), subtle but clinically important (lateral meniscus posterior attachment avulsion), obvious and unimportant to management (femoral condyle impaction injury), or subtle and possibly important (medial meniscocapsular junction tear). Paediatric-specific issues of note include tibial spine avulsion, normal difficulty visualising a thin ACL and posterolateral corner structures, and differentiation between incompletely closed physis and impaction fracture.

CONCLUSION

ACL tear is only the most obvious sign of a complex injury involving multiple structures. Awareness of the spectrum of secondary findings illustrated here and the features distinguishing them from normal variation can aid in accurate assessment of ACL tears and related injuries, enabling effective treatment planning and assessment of prognosis.

TEACHING POINTS

• The ACL in children normally appears thin or attenuated, while thickening and oedema suggest tear. • Displaced medial meniscal tears are significantly more common later post-injury than immediately. • The meniscofemoral ligaments merge with the posterior lateral meniscus, complicating tear assessment. • Tibial plateau impaction fractures can be difficult to distinguish from a partially closed physis. • Axial MR sequences are more sensitive/specific than coronal for diagnosis of medial collateral ligament (MCL) injury.

Coronal oblique imaging of the knee: can it increase radiologists' confidence in diagnosing posterior root meniscal tears?

AIM

To investigate the utility of the coronal oblique sequence in the interrogation of posterior root meniscal lesions.

MATERIALS AND METHODS

Following international review board approval, 62 consecutive knee arthroscopy cases were referred to the musculoskeletal (MSK) radiologists from the same orthopaedic surgeon for imaging/surgical correlation of the posterior meniscal roots. Of 62 cases, 45 lateral and 46 medial menisci met the inclusion criteria. Imaging evaluation was performed with standard magnetic resonance imaging (MRI) sequences, including a coronal oblique proton density sequence. Two blinded fellowship-trained MSK radiologists independently evaluated the menisci on standard sequences indicating whether a tear was identified and then specifying a confidence score using a scale of 1-3 on each study interpreted. Immediately thereafter, the coronal oblique sequence was evaluated using the same method. Statistics were performed on meniscal lesions involving the posterior horn/root junction or isolated root tears comparing confidence scores.

RESULTS

Reader A identified nine posterior horn/root junction tears and 14 isolated root tears. Following the addition of the coronal oblique sequence, confidence scores increased in three of 14 (21.4%) isolated root tears. All three final reads were concordant with arthroscopy. Reader B identified 10 posterior horn/root junction tears and 19 isolated root tears. The confidence score increased in six cases: five of 19 (26.3%) isolated root tears and one of 10 (10%) posterior horn/root junction tears. All six final reads were concordant with arthroscopy. Kappa coefficients indicated near perfect agreement.

CONCLUSION

The coronal oblique sequence increased reader confidence in nearly 24% of the posterior root cases identified in this series.

Arthroscopic verification of objectivity of the orthopaedic examination and magnetic resonance imaging in intra-articular knee injury. Retrospective study

Introduction

Arthroscopy of the knee joint is regarded as the most objective diagnostic method in intra-articular knee joint lesions.

Aim

The purpose of this study was to assess the objectivity and diagnostic value of orthopaedic examination (OE) and magnetic resonance imaging (MRI) in reference to the arthroscopic result.

Material and methods

In a group of 113 patients treated by arthroscopic surgery for post-traumatic knee pathology between 2008 and 2010 in our department, accuracy of clinical and MRI findings that preceded surgery were studied retrospectively using a statistical method. Sensitivity, specificity, accuracy and predictive negative and positive values were the subject of analysis.

Results

In the presented trial, sensitivity values of the orthopaedic examination for injuries of the anterior cruciate ligament (ACL), meniscus medialis (MM), meniscus lateralis (ML) and chondral injuries (ChI) were 86%, 65%, 38% and 51%, respectively. Specificity values were 90%, 65%, 100% and 100%, respectively. The MR sensitivity and specificity values were 80%, 88%, 44% and 32%, and 86%, 64%, 93% and 97%, respectively.

Conclusions

Assessment of intra-articular knee joint lesions is a difficult diagnostic problem. In making a decision about arthroscopy of the knee joint, an appropriate sequence of examinations should be carried out: OE, MRI and arthroscopy. The improvement in the effectiveness of the orthopaedic examination and MRI can limit the too high frequency of diagnostic arthroscopies, which generates the risk of operation treatment and costs.

Verification bias: an under-recognized source of error in assessing the efficacy of MRI of the meniscii

RATIONALE AND OBJECTIVES

The sensitivity and specificity of magnetic resonance imaging (MRI) for diagnosis of meniscal tears has been studied extensively, with tears usually verified by surgery. However, surgically unverified cases are often not considered in these studies, leading to verification bias, which can falsely increase the sensitivity and decrease the specificity estimates. Our study suggests that such bias may be very common in the meniscal MRI literature, and illustrates techniques to detect and correct for such bias.

MATERIALS AND METHODS

PubMed was searched for articles estimating sensitivity and specificity of MRI for meniscal tears. These were assessed for verification bias, deemed potentially present if a study included any patients whose MRI findings were not surgically verified. Retrospective global sensitivity analysis (GSA) was performed when possible.

RESULTS

Thirty-nine of the 314 studies retrieved from PubMed specifically dealt with meniscal tears. All 39 included unverified patients, and hence, potential verification bias. Only seven articles included sufficient information to perform GSA. Of these, one showed definite verification bias, two showed no bias, and four others showed bias within certain ranges of disease prevalence. Only 9 of 39 acknowledged the possibility of verification bias.

CONCLUSION

Verification bias is underrecognized and potentially common in published estimates of the sensitivity and specificity of MRI for the diagnosis of meniscal tears. When possible, it should be avoided by proper study design. If unavoidable, it should be acknowledged. Investigators should tabulate unverified as well as verified data. Finally, verification bias should be estimated; if present, corrected estimates of sensitivity and specificity should be used. Our online web-based calculator makes this process relatively easy.

The clinical diagnosis of meniscal tear is not easy. Reliability of two clinical meniscal tests and magnetic resonance imaging

AIM

to clarify the reliability of two clinical meniscal tests, McMurray's and Apley's and the MRI imaging, in order to establish how to reduce unjustified arthroscopies.

METHODS

102 patients were selected out of 160. All patients were submitted to a triple clinical examination (by a young surgeon and two skilled surgeons), MRI and an arthroscopic procedure. The investigated clinical tests were McMurray's and Apley's test. The positivity or negativity of the tests and MRI were compared to arthroscopic findings. Arthroscopy is considered the gold standard for the diagnosis of meniscal lesions. We measured the length of the meniscal lesions in order to correlate it to the clinical findings.

RESULTS

From the clinical examination, we got the following data: McMurray's test: sensitivity 79.7%, specificity 78.5%, accuracy 79.4%, positive likelihood ratio 3.7, negative likelihood ratio 0.2. Apley's test: sensitivity 83.7%, specificity 71.4%, accuracy 80.3%, positive likelihood ratio 2.9, negative likelihood ratio 0.2. The composite assessment is strictly dependent on how the discordance of the two tests is evaluated. The assessment of the clinical tests was done even in relation to medial or lateral meniscal lesion. No statistical difference was found about the length of the meniscal tear. MRI gave the following results: sensitivity 78.3%, specificity 85.7%, accuracy 80.3%.

CONCLUSIONS

If we use, as diagnostic means, McMurray's and Apley's clinical tests and MRI as imaging procedure, we have an accuracy of about 80%. It is important to keep in mind that it is not possible to have the absolute certainty of make a correct diagnosis in case of meniscal lesions. Patients, too, have to be informed about the risk of a negative arthroscopy.

Footballer's Lateral Meniscus: Anterior Horn Tears of the Lateral Meniscus with a Stable Knee

This paper aimed to identify the characteristics of isolated anterior horn tear of the lateral meniscus in footballers who underwent arthroscopic surgery. We identified 8 patients with stable knee and no ligament injury, who had only isolated anterior horn tear of the lateral meniscus between 2007 and 2009. All 8 patients were footballers, comprising 7 men and 1 woman with mean age of 18.6 years. Arthroscopy revealed multiple longitudinal tears in 2 patients, longitudinal tear in 2 patients, degenerative tear in 3 patients, and flap tear in 1 patient. Two patients were treated by repair, five by partial excision, and one by rasping only. The mean Lysholm score was 65 before surgery and recovered to 89 at the last followup, on average 12 months after surgery. Anterior horn tear of the lateral meniscus in footballers with a stable knee is characterized by pain at the anterolateral aspect of the knee during knee extension, especially when kicking a ball, and pain during weight-bearing knee extension, together with MRI finding of hyperintense signal in the anterior horn of the lateral meniscus. Preoperative diagnosis may be possible based on these findings in footballers.

Magnetic resonance imaging of the knee: clinical significance of common findings

Magnetic resonance imaging (MRI) of the knee is a widely used study that accurately depicts internal derangement. However, the relevance of the findings on knee MRI to the patient's symptoms and clinical course may often be uncertain. This article discusses the clinical significance and natural history of several common findings on knee MRI examinations.