MR diagnosis of meniscal tears of the knee: analysis of error patterns

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.

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.

Suture configuration techniques have no effect on mid-term clinical outcomes of arthroscopic meniscus root repairs

BACKGROUND

The aim of this study was to evaluate the clinical and radiological outcomes of arthroscopic transtibial pullout repair (ATPR) for the medial meniscus with both two modified loop stitches (TLS) and two simple stitches (TSS) techniques.

METHODS

Between January 2013 and January 2016, 41 patients who had undergone ATPR for medial root tears with TLS and TSS techniques were retrospectively evaluated. The mean age at operation was 53 years (range 45-58). The mean follow-up period was 44.6 months (range 26-64). Lysholm knee score was used for clinical evaluation before and after surgery. For all patients, meniscal extrusion distances in the coronal plane were measured using magnetic resonance imaging and were recorded both preoperatively and at final follow-up.

RESULTS

There was no difference in terms of meniscus extrusion measurements between groups preoperatively (P > .05). Postoperative meniscus extrusion measurements were 2.1 ± 0.3 and 2.9 ± 0.6 in TLS and TSS groups, respectively. The difference between groups was statistically significant (P < .01). The increase in postoperative Lysholm score was found to be statistically significant in both groups (P < .01). Postoperative Lysholm scores were 88.8 ± 3.7 and 87.6 ± 4.8 in TLS and TSS groups, respectively. The difference between groups was statistically insignificant (P > .05).

CONCLUSIONS

There was a significant improvement in Lysholm knee scores postoperatively in patients that underwent transtibial pullout medial meniscus posterior root repair regardless of meniscus reduction level and suture configuration types. Although TLS technique was superior to TSS technique in terms of meniscus reduction, this meniscus reduction did not create any clinical difference at clinical outcome.

The International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine classification of knee meniscus tears: three-dimensional MRI and arthroscopy correlation

OBJECTIVES

To introduce MRI-based International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) classification system of meniscal tears and correlate it to the surgical findings from arthroscopy. We hypothesized that the ISAKOS classification will provide good inter-modality and inter-rater reliability for use in the routine clinical practice of radiologists and orthopedic surgeons.

METHODS

In this HIPAA-compliant cross-sectional study, there were 44 meniscus tears in 39 patients (26 males, 16 females). Consecutive arthroscopy-proven meniscal tears (March 2017 to December 2017) were evaluated by two board-certified musculoskeletal radiologists using isotropic three-dimensional (3D) MRI user-defined reconstructions. The surgically validated ISAKOS classification of meniscal tears was used to describe medial meniscus (MM) and lateral meniscus (LM) tears. Prevalence-adjusted bias-adjusted kappa (PABAK) and conventional kappa, and paired t test and intra-class correlation coefficient (ICC) were calculated for categorical and numerical variables, respectively.

RESULTS

For the MM, the PABAK for location, depth, length (ICC), pattern, quality of meniscus tissue, and zone was 0.7-1, 0.65, 0.57, 0.67, 0.78, and 0.39-0.7, respectively. For the LM, the PABAK for location, depth, length (ICC), pattern, quality of meniscus tissue, zone, and central to popliteus hiatus was 0.57-0.95, 0.57, 0.74, 0.93, 0.38, 0.52-0.67, and 0.48, respectively. The mean tear lengths were larger on MRI than on arthroscopy (mean difference MM 9.74 mm (6.66 mm, 12.81 mm; p < 0.001), mean difference LM 4.04 mm (0.31 mm, 7.76 mm; p = 0.034)).

CONCLUSIONS

The ISAKOS classification of meniscal tears on 3D MRI provides mostly moderate agreement, which was similar to the agreement at arthroscopy.

KEY POINTS

• There is a fair to good inter-method correlation in most categories of ISAKOS meniscus tear classification. • The tear lengths are significantly larger on MRI than on arthroscopy. • The inter-reader correlation on 3D MRI is moderate to excellent, with the exception of lateral meniscus tear patterns.

Common Mistakes and Pitfalls in Magnetic Resonance Imaging of the Knee

This pictorial review presents an overview of common interpretation errors and pitfalls in magnetic resonance imaging (MRI) of the knee. Instead of being exhaustive, we will emphasize those pitfalls that are most commonly encountered by young residents or less experienced radiologists.

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.

Comparison between conservative treatment and arthroscopic pull-out repair of the medial meniscus root tear and analysis of prognostic factors for the determination of repair indication

INTRODUCTION

This study was undertaken to compare the clinical outcomes between the conservative treatment and pull-out repair of the medial meniscus root tear (MMRT), and to analyze the prognostic factors of the MMRT repair for the determination of repair indication.

MATERIALS AND METHODS

38 patients, diagnosed with a MMRT between August 2010 and February 2012, were retrospectively evaluated. Among these patients, 25 patients (pull-out repair group) underwent arthroscopic pull-out repair and the remaining 13 patients (conservative treatment group) underwent conservative management. Two groups were compared using the final clinical outcomes (using Tegner and Lysholm activity scale, IKDC subjective score). For the analysis of prognostic factors of the pull-out repair, patients' factors, radiologic, and magnetic resonance imaging factors were evaluated. Degrees of varus alignment (≥5°) and cartilage status (≥outerbridge III) were employed as a cut-off value in comparing the final clinical outcomes among the subgroups.

RESULTS

In the final clinical results, the MMRT pull-out repair group had better IKDC subjective scores (p < 0.001), Tegner and Lysholm activity scale (p = 0.017). In the MMRT pull-out repair group, mild varus knee patient achieved better clinical outcome than the severe varus knee patient (p = 0.006). And the mild cartilage degenerative patient group achieved better outcomes than the severe cartilage degenerative patient group (p = 0.009). However, there was no significant difference between the severe varus alignment group and conservative treatment group (p = 0.487). Severe cartilage changes also show no significant difference (p = 0.643).

CONCLUSIONS

The MMRT pull-out repair group had better clinical results than that the conservative treatment group. However, severe varus alignment and severe degeneration of cartilage status were a poor prognostic factor, and there was no significant difference between the severe varus alignment or severe cartilage change and the conservative treatment group in the clinical results. The other optional treatment could be recommended for patients who have MMRT with a severe varus knee alignment or severe cartilage.

Low prevalence of isolated medial meniscal tears in young females with stable knees

The information regarding isolated tears of the meniscus in stable knees (ie, without cruciate ligament tears), specifically in a younger population, is scarce. Although surgical treatment is preferred for young patients with meniscal tears, the diagnosis at this age may be misled by other sources of knee pain. The purpose of this study was to report on the prevalence and sex variance of isolated meniscal tears in a younger population based on arthroscopic findings. From a database of 2425 arthroscopic knee surgeries performed over a period of 6 years, 591 patients (480 males and 111 females) younger than 40 years were included. Patients were divided into 5 age groups and subdivided according to their surgical findings. Measures included the prevalence of meniscal tears according to sex and age groups and also odds ratio calculations for the presence of meniscal tears. Of 591 arthroscopic surgeries in young patients with stable knees, only 6 females (vs 87 males) younger than 30 years had isolated medial meniscus tears. The number of stable knees without meniscal tear at arthroscopy in all age groups was relatively high. The odds ratio for having a medial meniscal tear was significantly higher in males. The results suggest a protective mechanism for isolated medial meniscal tears in younger females as opposed to other injuries of the knee. Isolated medial meniscus tears in stable knees are uncommon in females younger than 30 years; thus, young females with suspected tears should be reevaluated and treated conservatively before considering surgical solutions.

Indications requiring preoperative magnetic resonance imaging before knee arthroscopy

INTRODUCTION

Knee arthroscopy knee is gold standard in diagnosis and simultaneous treatment of knee disorders. But most patients undergo magnetic resonance imaging (MRI) before arthroscopy, although MRI results are not always consistent with arthroscopic findings. This raises the question in which suspected diagnoses MRI really has influence on diagnosis and consecutive surgical therapy.

MATERIAL AND METHODS

Preoperative MRI of 330 patients with knee disorders were compared with arthroscopic findings. The MRI were performed by 23 radiologists without specialization in musculoskeletal diagnostics. Specificity, sensitivity, negative/positive predictive value and accuracy of MRI were calculated in comparison to arthroscopic findings.

RESULTS

We found sensitivity/specificity of 58%/93% for anterior horn, 94%/46% for posterior horn of medial meniscus and 71%/81% for anterior and 62%/82% for posterior horn of lateral meniscus. Related to anterior cruciate ligament injuries we showed sensitivity/specificity of 82%/91% for grade 0 + I and 72%/96% for grade II + III. For Cartilage damage sensitivity/specificity of 98%/7% for grade I-, 89%/29% for grade II-, 96%/38% for grade III- and 96%/69% for grade IV-lesions were revealed.

CONCLUSIONS

The MRI should not be used as routine diagnostic tool for knee pain. No relevant information for meniscal lesions and anterior cruciate ligament ruptures has been gained with MRI from non-specialized outside imaging centres. The MRI should not be used as routine diagnostic tool for knee pain. No relevant information for meniscal lesions and anterior cruciate ligament ruptures has been gained with MRI from non-specialized outside imaging centres.

Correlation of histological examination of meniscus with MR images: focused on high signal intensity of the meniscus not caused by definite meniscal tear and impact on mr diagnosis of tears

Objective

To document the causes of high signal intensity of the meniscus which is not caused by definite meniscal tears on MR imaging, through correlation with histological examination.

Materials and Methods

For the correlation between the MR image and histology, we obtained prospectively 31 meniscal specimens from 21 patients. Proton density-weighted turbo spin-echo MR images were used. Minimal tear, thinning of the lamellar layer, degeneration of the central layer, and radial tie fibers were detected upon histological examination, and were correlated with the corresponding MR images.

Results

Minimal tear of the lamellar layer was seen in 60 zones out of 100 slides. On MR images, 29 (48.3%) of these 60 zones had high signal intensity. Thinning of the lamellar layer was seen in 24 zones, with 7 (29.2%) having high signal intensity. 57 central zones showed degenerative change in the central layer and high signal intensity on all corresponding MR images. Radial tie fibers in the central layer appeared as high signal intensity areas.

Conclusion

Minimal tear and thinning of the lamellar layer, degeneration and radial tie fibers of the central layer of the meniscus cause high signal intensity on MR images.

How I diagnose meniscal tears on knee MRI

OBJECTIVE

The goal of this article is to summarize the literature about the diagnosis of meniscal tears on MRI including the normal appearance of the meniscus and the appearance of the various types of meniscal tears. In addition, I discuss my experience with the causes of errors in the MR diagnosis of meniscal abnormalities and the nuances of meniscal abnormalities that can mimic a meniscal tear.

CONCLUSION

MRI is a highly accurate imaging method for diagnosing meniscal tears. To avoid errors in diagnosing meniscal tears, those interpreting MR examinations of the knee need to be aware of the attachments of the menisci and the normal variations in meniscal anatomy that may resemble a meniscal tear. In addition, by being aware of the patterns of meniscal tears, it is easier to diagnose the less common tears.

Accuracy of magnetic resonance imaging of the knee in the community setting

BACKGROUND

Magnetic resonance imaging (MRI) is routinely used in the diagnosis of sports-related knee injuries.

PURPOSE

To determine the accuracy, sensitivity, and specificity of MRI compared with clinical evaluation in the diagnosis of meniscal pathology when the MRI facility and the radiologist are not preselected.

METHODS

A total of 288 knee arthroscopies were retrospectively compared. Patients were divided into 3 groups: those who had MRI performed and interpreted at a single institution, MRI performed and interpreted at community facilities, or a clinical evaluation by a senior orthopaedic surgeon.

RESULTS

The sensitivity, specificity, and accuracy of the diagnosis of medial meniscal pathology at a single institution were 90%, 59%, 76%; in community facilities, 73%, 68%, 70%; and by a clinical evaluation, 93%, 55%, 73%, respectively. For lateral meniscal pathology, the results were as follows: single institution, 75%, 76%, 81%; community facilities, 60%, 88%, 79%; and clinical evaluation, 45%, 90%, 79%, respectively. Sensitivity for medial meniscus was greater than for lateral meniscus, but specificity of diagnosis was better for lateral meniscus by MRI and clinical evaluation. While not statistically significant, there was increased sensitivity in the diagnosis of medial meniscus and lateral meniscus at SIs, but they have less specificity than at community facilities. The number of false-positive diagnoses (ie, no intra-articular pathology) that resulted in surgery was 4 of 288 (1.39%). The overall accuracy for medial meniscus by MRI was 73% vs 73% for clinical evaluation. The overall accuracy for MRI for lateral meniscus was 78% vs 79% for clinical evaluation.

CONCLUSION

Routine MRI may not be more beneficial than clinical evaluation when there is no preselection of MRI facility and interpreting radiologist.

CLINICAL RELEVANCE

The use of MRI for diagnosing meniscal pathology should be reserved for those cases where the orthopaedic clinical examination is ambiguous.

Chiropractic management of a medial meniscus tear in a patient with tibiofemoral degeneration: a case report

OBJECTIVE

The purpose of this case report is to describe and discuss the clinical diagnosis of a medial meniscus tear in an older patient using a multimodal management approach provided by a chiropractor.

CLINICAL FEATURES

A 60-year-old woman reported to a chiropractic clinic with left knee pain and swelling. The history and physical examination findings suggested a medial meniscus tear, which was confirmed with magnetic resonance imaging.

INTERVENTION AND OUTCOME

Treatment consisted of therapeutic ultrasound; rest, ice, compression, and elevation protocol; soft tissue therapy using effleurage and lymphatic drainage; chiropractic mechanically assisted adjusting techniques to the left knee using a handheld mechanical thrusting instrument; sports taping applied to assist facilitation of the vastus medialis obliquus; and a specific rehabilitation program aimed at strengthening this musculature. The patient's pain was assessed using a quadruple numeric pain scale. Function of the left knee was examined using McMurray, Apley, and a variation of Helfet orthopedic tests, as well as joint line tenderness. Monitoring was done at the initial consultation and at the sixth and 12th treatments. The patient reported being able to walk, swim, and ride a bicycle asymptomatically. Her pain score at the concluding visit was 16.7%, indicating low-intensity pain.

CONCLUSION

This case indicated that conservative management of a meniscus tear through a chiropractic multimodal treatment approach provided an alternative or adjunctive therapy to routine orthopedic surgery for this patient.

Arthroscopic pullout suture repair of posterior root tear of the medial meniscus: radiographic and clinical results with a 2-year follow-up

PURPOSE

This study was undertaken to document the short-term clinical efficacy of arthroscopic pullout suture repair in treating posterior root tears of the medial meniscus.

METHODS

From March 2004 to August 2006, 26 patients (27 knees) with posterior root tears of the medial meniscus were treated with arthroscopic pullout suture repair surgery by the senior author. Of these, 20 consecutive patients (21 knees) with a minimum of 2 years' follow-up treated by arthroscopic pullout suture repair were analyzed. Clinical results by use of the Lysholm knee and Hospital for Special Surgery scores and radiographic grade were evaluated, both preoperatively and at final follow-up. In addition, the second-look arthroscopic findings for 10 knees were analyzed.

RESULTS

A radiographic evaluation using the criteria of Kellgren and Lawrence at final follow-up showed an increase in radiographic grade by 1 grade in only 1 knee. On the second-look arthroscopies performed in 10 knees (47.6%), all repaired menisci had healed completely without additional chondral lesions in the knee. The mean Hospital for Special Surgery scores improved from 61.1 preoperatively to 93.8 at final follow-up (P < .0001), and the mean preoperative Lysholm knee scores improved from 57.0 to 93.1 at final follow-up (P < .0001). Retear was found in 1 knee at the 6-month follow-up, and reoperation was performed with the same procedure used for the index surgery.

CONCLUSIONS

Arthroscopic pullout suture repair is an effective treatment for alleviating meniscal symptoms in patients with a symptomatic posterior root tear of the medial meniscus with degenerated articular cartilage of less than grade III. In addition, no discernable degenerative arthritic changes were found in terms of radiographic features with our limited short-term follow-up.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

The role of preoperative MRI in knee arthroscopy: a retrospective analysis of 2,000 patients

The aim of this study was to investigate, to what extent routine preoperative MRI scans could set the indications for knee arthroscopies and reduce the number of diagnostic arthroscopies. For this retrospective cohort study, 1,000 patients who had knee arthroscopies documented in 1994/1995 were compared with 1,000 patients that were treated in 2004/2005. The preoperative diagnoses that gave indications for knee arthroscopy were compared with the intraoperative findings. The congruence of preoperative diagnosis with the intraoperative findings was evaluated comparing both study populations. The number of patients who were referred to orthopaedic trauma surgeons with MRI increased from 24% to 56%. A high congruence of preoperative diagnosis and intraoperative findings was found in 49% in 1994/1995 and 55% in 2004/2005. However, regarding the most important outcome parameter, the number of diagnostic arthroscopies, no improvement was found (3% in both periods). The presented data suggests that MRI scans are not routinely necessary as an indication for knee arthroscopy, as clinical examination and plain radiograph are sufficient. However, MRI scans do allow a more detailed characterization of the expected findings and can therefore be helpful in therapy planning.

MR diagnosis of posterior root tears of the lateral meniscus using arthroscopy as the reference standard

OBJECTIVE

The purpose of our study was to determine whether tears of the posterior root of the lateral meniscus can be diagnosed using standard MR criteria of a meniscal tear in the presence or absence of an anterior cruciate ligament (ACL) tear.

MATERIALS AND METHODS

From a series of 559 knee MR examinations with arthroscopic correlation, we selected all 16 proven tears isolated to the posterior root of the lateral meniscus for retrospective blinded review, along with 45 cases of arthroscopically intact lateral meniscal posterior roots. The reviewers categorized whether there was a torn, possibly torn, or intact root based on three specific coronal and three specific sagittal image locations.

RESULTS

When all possibly torn roots were considered as torn, the sensitivity and specificity for diagnosis of a root tear were 93% and 89%, respectively. The observers' overall diagnosis of a tear based on all images gave a higher combined sensitivity and specificity than if the diagnosis of a tear had been based on one or any combination of the three coronal and three sagittal locations. Root tears were significantly more common in the presence of an ACL tear (p < 0.0001), but the presence or absence of an ACL tear did not change MR diagnostic accuracy.

CONCLUSION

The standard MR criteria of meniscal distortion and signal to the surface can be used to diagnose lateral meniscal root tears. The presence or absence of an ACL tear did not change diagnostic accuracy.

MRI of the knee: how do field strength and radiologist's experience influence diagnostic accuracy and interobserver correlation in assessing chondral and meniscal lesions and the integrity of the anterior cruciate ligament?

Accuracy of MRI reports is taken for granted. In this paper the inter-observer reliability in the interpretation of meniscal lesions, degree of chondropathy, and integrity of the ACL was analyzed while taking the radiologist's experience and field strength into account. Fifty-two MRI studies of knees were interpreted by 11 radiologists independently. Twenty-two were acquired on 1.0-T, 20 on 1.5-T, and 10 on 3.0-T systems. Four of the radiologists had more than 5 years and seven had 3 to 5 years of experience in interpreting MRI studies. The findings were compared with the intra-operative findings. Inter-observer variance, specificity, and sensitivity were evaluated for each field strength. Inter-observer correlation ranged between 0.370 for cartilage lesions and 0.597 for meniscal tears. Correlation values did not increase with experience or field strength. The number of false reports was dependent on the observer, but not on field strength. The rate of false interpretations was significantly higher for most criteria in the less experienced group. In conclusion, inter-observer correlation was low, although the diagnostic criteria were defined. The use of the classification scheme should be standardized by uniform training. Radiologist experience seems to be more important than field strength.

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

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

Comparison of image quality in magnetic resonance imaging of the knee at 1.5 and 3.0 Tesla using 32-channel receiver coils

We examined to what degree the visualization of anatomic structures in the human knee is improved using 3.0-T magnetic resonance imaging (MRI) and many element RF receive coils as compared to 1.5 T. We imaged 20 knees at 1.5 and 3.0 T using T2-weighted STIR, T2-weighted gradient echo, T1-weighted spin-echo, true-FISP and T2-weighted fast spin echo techniques in conjunction with 32-element RF coil arrays. The 3.0-T examination was considerably faster than its 1.5-T counterpart. A superior subjective visibility at 3.0 T vs 1.5 T was found in 27 of 50 evaluated structures (meniscus, ligaments) with the exception of true-FISP techniques. The 3.0-T examination provided a better visibility (evaluated by blinded consensus-reading by two radiologists) of small structures such as the ligamentum transversum genu. Also, cartilage was better delineated at 3.0 T. A 23% increased average signal-to-noise ratio as assessed using a temporal filter was observed at 3.0 T as compared to 1.5 T. At 3.0 T, imaging of the human knee is faster and results in a subjective visibility of anatomic structures that is superior to and competitive with 1.5 T.