Clinical,radiologic and arthroscopic assessment and treatment of bilateral discoid lateral meniscus

The purpose of the study is to evaluate clinical, radiologic and arthroscopic features of bilateral discoid lateral meniscus and to assess the outcome of arthroscopic meniscectomy. Among the 177 arthroscopies performed for discoid lateral meniscus between January 1993 and January 2004, 12 were bilateral. The clinical and radiologic evaluation was done from the records. The type of discoid meniscus, the type of tear was assessed arthroscopically. All patients underwent arthroscopic meniscectomy. Patients were followed up for a minimum period of 2 years. All patients had pain as presenting symptom. Eight patients presented with bilateral knee pain and four patients developed pain in the opposite knee after the affected knee was treated. The classically described thud was present in 11 knees. The widening of the joint space was found in 13 knee radiographs; 14 knees had complete type, nine had incomplete type and one had ring type of discoid lateral meniscus on arthroscopic evaluation; 20 knees involving 10 complete types, all incomplete types and ring type of discoid lateral meniscus showed obvious meniscal tears. The remaining four meniscus showed softening of a portion of the meniscus. Underlying intra-substance tear was visualized arthroscopically in the softened areas on saucerisation. All but one discoid menisci underwent arthroscopic partial central meniscectomy. When followed up for an average period of 32.6 months 19 knees showed excellent results and 5 knees good results. Possibility of bilaterality should be suspected in discoid lateral meniscus. Softening of meniscus denotes underlying intra-substance tear. This finding has not been described in the literature so far. Arthroscopic partial meniscectomy gives good results in symptomatic bilateral discoid meniscus. This to our knowledge is the largest series of bilateral discoid lateral menisci.     

Arthroscopic management of lateral meniscal cysts

This study presents seven cases of lateral meniscal cysts treated arthroscopically. All were noted to have meniscal lesions at the time of surgery; there were five flap tears and two radial tears. Partial arthroscopic meniscectomy was performed and the contents of the cysts were manipulated into the joint in six of seven cases. One patient underwent open cyst excision in addition to partial arthroscopic meniscectomy. Followup ranged from 18 months to 4 years with an average of 28 months. There were no cyst recurrences. The pathologic basis of the meniscal cyst is controversial, but recent work suggests the etiology is infiltration of joint fluid through micro and macro tears in the meniscus. Partial meniscectomy retains valuable meniscal function while minimizing the likelihood of cyst reformation. We found arthroscopic partial meniscectomy with manipulation of the contents of the cyst into the joint to be a successful alternative to complete open meniscectomy.     

Healed meniscal tears in unstable knees. A long-term followup of seven years

Peripheral vertical ruptures of the medial (N = 24) and the lateral (N = 4) meniscus were repaired in 28 patients (mean age, 27 years). They all had an ACL lesion, combined in 26 cases with a MCL tear. These injuries were reconstructed or sutured during the same session as the meniscus repairs. Approximately 1 year later, meniscal healing was proven arthroscopically in 20 and the other 8 had no clinical signs of meniscal rerupture. All patients were reexamined between 6 to 8 years after the initial repair. Instrumented stability testing, the Lysholm knee function score and an activity score (Tegner) were used. The patients' subjective evaluations were also recorded. In spite of the previous reconstruction, all knees were quite unstable (mean +5 mm increased laxity compared with the uninjured side). At followup, 3 of the 28 repaired menisci (11%) had reruptured in connection with a minor trauma during sports or daily activity. The knee function score averaged 88 points, the activity level dropped 2 steps compared with activities before injury (from 7 to 5). Twenty patients were satisfied with the results, 5 partly satisfied, and 3 not satisfied. A healed meniscal tear has a good chance of survival in an unstable knee. The most critical period of meniscal repair probably lies in the healing period just after surgery.     

Imaging of meniscal cyst of the knee in three cases

Three cases of solitary meniscal cyst in the knee have recently been diagnosed in our departments using ultrasound and nuclear magnetic resonance (MRI). Two cysts involved the lateral and one the medial meniscus. The appearance of these lesions on ultrasound and MR images is shown. All three cysts had low intensity on T1-weighted images and high intensity on T2-weighted images and clearly communicated with a large horizontal tear in the meniscus. Ultrasonography showed a relatively hypoechoic lesion and, in the two cases of lateral meniscal cyst, focal areas of relatively increased echoes which are probably due to meniscal debris. Ultrasound showed the abnormal meniscus in both of these cases. MRI is the best way of showing the cyst and an accompanying meniscal tear but, where MRI is not available, ultrasound may be an easy and inexpensive way of making a diagnosis whether or not it is used in conjunction with positive contrast arthrography.     

T-Fix anchor sutures for arthroscopic meniscal repair

The results of arthroscopically repaired meniscal tears with the T-Fix system in a short-term follow-up of 6 months was assessed in a non-comparative, prospective study. The T-Fix device consists of a short, rigid Delrin T attached to a braided, non-absorbable, polyester suture which is preloaded inside and deployed through a delivery (spinal) needle. The T grabs inside the tissue and provides an anchor for the suture. Twenty menisci in 20 patients (mean age 29 years) were repaired. Sports-related injuries were documented in 18 patients. In 15 patients, meniscus tears were repaired 6 months or more after injury. Half of the patients had isolated meniscus injuries. Associated injuries included anterior cruciate ligament (ACL), medial or lateral collateral ligament ruptures. These were not treated at the time of meniscal surgery except for an ACL reconstruction. All tears were longitudinal and positioned mainly in the posterior horn of the medial meniscus. A total of 70 T-Fixes were used with an average of 3 per patient (range 2–7). Only 4 T-Fixes (6%) were unsuccessfully placed, and this occurred early on in the series in 4 patients. In 90% of the patients, the postoperative activity levels returned to preoperative levels, and the clinical symptoms had either resolved or were experienced at a higher level of activity. The T-Fix device was relatively easy to use and could be reliably placed in the meniscus. Postoperatively, there were no complications directly associated with the device. However, further studies are needed to confirmed these results in a long-term follow-up in a larger patient population.     

Arthroscopy alone or in association with open cystectomy: in treatment of lateral meniscal cysts

We retrospectively the results in 27 knees (26 patients) with cysts of the lateral meniscus. All patients had a meniscal tear (20 horizontal, 7 transverse) and pain over the lateral joint line with a palpable mass. The pathology was in the middle or anterior one-third of the meniscus. Arthroscopic surgery was performed in 22 knees, consisting of partial excision of meniscal tear, leaving a peripheral rim, coupled with débridement of the cyst; open cystectomy was performed in the remaining 5 knees. Average follow-up was 58 months (range 9-110). All patients but two were satisfied with the results.     

Comparison of two procedures for meniscal cysts. A report of 35 patients with a mean follow-up of 33 months

BACKGROUND: The cause, pathogenesis, and appropriate treatment of meniscal cysts remain controversial. PURPOSE: We wanted to evaluate the results of treatment of meniscal cysts with two different operative procedures. STUDY DESIGN: Prospective cohort study. METHODS: Two different operative procedures were compared. Sixteen patients (group 1) had an open excision of the cyst performed in addition to arthroscopic examination of the knee. Nineteen patients (group 2) were treated entirely arthroscopically. The postoperative treatment course was the same for both groups. The mean length of follow-up was 33 months. RESULTS: The results were excellent or good in 86% of the patients (30 of 35) and were equally good for both procedures. Patients with degenerative changes of the knee joint seemed to have a less favorable outcome. CONCLUSIONS: Good or excellent results can be expected from either open or arthroscopic treatment of meniscal cysts.     

Popliteal cysts in adults. Prevalence, associated intraarticular lesions, and results after arthroscopic treatment.

The objective of this prospective study was to determine the prevalence of popliteal cysts and the associated intraarticular lesions in a group of 100 patients scheduled for arthroscopic surgery of the knee and to evaluate the results of arthroscopic treatment for these intraarticular lesions without removal of the cyst. One hundred patients without any knee complaints served as a control group. The diagnosis of a popliteal cyst was made on the basis of ultrasonography. The prevalence of popliteal cysts was 20% in the study group and 0% in the control group. Patients with a popliteal cyst had a significantly higher prevalence of medial meniscal tears (70% versus 19%) and of chondral lesions (85% versus 28%). Tears of the lateral meniscus, however, were more evenly distributed (20% versus 36%). Sixteen of 20 patients with a popliteal cyst were available for a follow-up examination 1 to 3 years after the arthroscopic procedure. Eleven popliteal cysts had persisted. Chondral lesions were the most relevant prognostic factor; all patients with persisting cysts had grade III or grade IV lesions. We conclude that the popliteal cyst is a secondary phenomenon and that treatment should address the underlying intraarticular lesions. In cases of osteoarthritis it may be impossible to treat the chondral lesion successfully in terms of eliminating the effusion.     

Decline in clinical scores at long-term follow-up of arthroscopically treated discoid lateral meniscus in children

Purpose

The purpose of this study was to examine the long-term clinical outcomes of arthroscopic partial meniscectomy for the treatment of discoid lateral meniscus in children.

Methods

A previous study identified 34 consecutive patients that underwent arthroscopic meniscal saucerization by one of the two surgeons between 1997 and 2002. Patients were asked to complete several outcomes questionnaires and were given the opportunity to receive a knee exam performed by their treating surgeon.

Results

Of the 34 eligible patients, 21 agreed to participate. Seventeen patients (19 knees) had greater than 2-year follow-up, with an average follow-up of 11.0 years (range 3.4–16.6 years). Average age at the time of surgery was 9.3 years. Average IKDC, Kujala, and Lysholm scores at follow-up were 82.8?±?28.9, 86.6?±?15.2, and 83.7?±?18.6, respectively. In addition, median Marx and Tegner scores were 5 (range 0–14) and 6 (range 3–8), respectively. Stratifying the Lysholm scores revealed outcomes that were 45.4% “excellent”, 16.7% “good”, 25.0% “fair”, and 16.7% “poor”. In total, 36.8% (7 of 19) of knees underwent at least one subsequent surgical procedure. There were no significant associations between outcome scores and discoid type, meniscal stability, location of instability, or age at time of surgery.

Conclusions

The results of the current study suggest that clinical outcome scores decline over time in patients treated arthroscopically for symptomatic discoid meniscus. Compared to our previous study with 2-year follow-up, there is an increased incidence of knee pain and mechanical/functional limitations. The overall modest, long-term results of this study illustrate the need for improved operative treatments for symptomatic discoid meniscus in children to prevent progressive, long-term clinical decline in these patients.

     

Meniscal cysts

Meniscal cysts are cysts that occur as a direct extension, or within the substance of the meniscus. The incidence varies in reports from 1% to 20% and are much more common laterally. They usually present as joint-line pain, swelling, or both in young adult men, and are often associated with meniscal tears. The exact etiology of meniscal cysts is unknown. A myxoid degenerative process is identified histologically. There is often a history of precedent trauma. Diagnosis is often suspected clinically and can be confirmed by arthrogram, CT, or MRI when necessary. Conservative treatment in the patient with few symptoms is recommended. Should the cyst become significantly symptomatic, it is necessary to treat the meniscal pathology to prevent a cyst recurrence. At the present time it is our recommendation that this be done by arthroscopically resecting the meniscus back to normal meniscus and either aspirating and injecting the cyst with steroid or local cyst excision if the aspiration and injection fails. If no meniscal tear is documented at arthroscopy, exploration and excision of the cyst are recommended.     

Symptomatic ring-shaped lateral meniscus: magnetic resonance imaging and arthroscopy

A ring-shaped lateral meniscus is a very rare entity within the spectrum of abnormalities of lateral meniscus. We present the second case in the literature of a symptomatic ring-shaped lateral meniscus in combination with a meniscal cyst and in association with an osteochondritis dissecans lesion of the medial femoral condyle. A potential pitfall of magnetic resonance imaging (i.e., displaced meniscal tear) is addressed in the diagnosis of this entity, as well as the role of magnetic resonance imaging in revealing associated abnormalities.     

Characteristics of displaceable and nondisplaceable meniscal tears at kinematic MR imaging of the knee

PURPOSE: To prospectively determine if kinematic magnetic resonance (MR) imaging of the knee may demonstrate displacement of menisci with tears and, if so, to characterize displaceable and nondisplaceable meniscal tears. MATERIALS AND METHODS: The study was approved by the hospital's review board, and informed consent was obtained. Forty-two patients (30 men, 12 women; mean age, 36.9 years) with 43 arthroscopically documented meniscal tears visible at 1.5-T MR imaging underwent kinematic MR imaging with an open-configuration 0.5-T MR imager with their knees in supine neutral, supine with 90 degrees flexion and external or internal rotation, and upright weight-bearing positions. Analysis of meniscal movement was performed in different knee positions in the coronal MR imaging plane. Meniscal displacement--that is, meniscal movement of 3 mm or more (in the medial direction for the medial meniscus, in the lateral direction for the lateral meniscus)--was compared with the patient's pain level as assessed with a visual analog scale by using analysis of variance. RESULTS: Between the different knee positions, meniscal displacement of 3 mm or more (displaceable meniscal tears) was noted in 18 (42%) of 43 menisci with tears. Simultaneous occurrence of grade II or III ipsilateral collateral ligament lesions was present in all 18 displaceable meniscal tears, whereas a normal-appearing collateral ligament or collateral ligament lesion (grade I) was present in 22 of 25 nondisplaceable tears (P < .05). Displaced menisci most commonly had complex, radial, or longitudinal tear configurations (16 of 18, 89%). Patients with displaceable meniscal tears had significantly more pain than did patients with nondisplaceable meniscal tears (P < .001), independent of the concomitant knee abnormalities. CONCLUSION: Displaceable meniscal tears usually have longitudinal, radial, or complex configurations; such tears are associated with substantial ipsilateral collateral ligament lesions and pain.     

Analysis of meniscal and chondral lesions accompanying anterior cruciate ligament tears: relationship with age,time from injury,and level of sport

The purposes of this multi-center study were: (a) to document the location and type of meniscal and chondral lesions that accompany anterior cruciate ligament (ACL) tears, and (b) to test for possible relationships between these lesions and patient age, time from initial injury (TFI), and sports level (i.e., recreation, amateur, professional, and national). The cases of 764 patients with ACL tears who underwent arthroscopy for the first time were retrospectively analyzed. The group included 684 males and 80 females of mean age 27 years (range 14–59 years). The mean TFI was 19.8 months (range 0.2–360 months). Eighty-seven percent of the group engaged in regular sporting activity. Thirty-seven percent had medial meniscal tears, 16% had lateral meniscal tears, and 20% had tears of both menisci. The most common tear types were longitudinal tears in the posterior and middle horns of both menisci. Tears of the lateral meniscus were more centrally located than those of the medial meniscus. Incomplete tears and radial tears were significantly more common in the lateral meniscus. Nineteen percent of the knees had one or more chondral lesions. Sixty percent of the chondral lesions were located in the medial tibio-femoral compartment. Patient age was statistically associated with presence of a medial meniscal tear, presence of a grade 3 or 4 chondral lesion, and presence of a complex tear of the medial meniscus. Sports level was not statistically related to any of the parameters studied. The odds of having a medial meniscal tear at 2 to 5 years TFI were 2.2 times higher than the odds in the first year post-injury, and the odds at >5 years were 5.9 times higher than at 0 to 12 months TFI. The frequency of lateral meniscal tear remained fairly constant at 2 years TFI. The odds of having a grade 3 or 4 chondral lesion were 2.7 times greater at 2 to 5 years TFI than they were at 1 year post-injury, and these odds increased to 4.7 when patients at >5 years TFI were compared to those in the 2 to 5 years category. Multivariate analysis demonstrated that TFI and age were equally important predictors of lateral meniscal tears and of grade 3 or 4 chondral lesions; however, TFI was the better predictor of medial meniscal tear.This multi-center study was performed by the Turkish Society of Sports Traumatology, Arthroscopy and Knee Surgery. It was presented as a poster at the ESSKA 2000 Congress in London, UK     

Arthroscopic meniscus repair: inside-out technique vs. Biofix meniscus arrow

A retrospective study evaluated meniscal suturing using an inside-out technique vs. an all-inside technique (Biofix meniscus Arrow). Fifty-five knees in 55 patients who underwent closed meniscus repair between 1985 and 1995 were divided in two groups: 20 managed by an inside-out technique; and 35 managed by an all-inside technique. All patients underwent the same postoperative program of partial weight bearing, immediate motion, and rehabilitation of the knee. They were subjected to a clinical examination using Hospital for Special Surgery knee rating system. The mean follow-up was 13 years, 2 months (11 years, 11 months–15 years, 4 months) in the inside-out group and 6 years, 5 months (6 years–6 years 10 months) in the Biofix Arrow group. Sixteen patients also had an anterior cruciate ligament injury, of which six were repaired at the time of meniscus repair and one 6 years after meniscal repair. Thirty-nine patients had an excellent or good result (87% satisfactory outcome), three had a fair result, and three had a poor result. Meniscal suturing thus provides good clinical long-term results. The advantages of an all-inside technique include short operating time, superfluous capsular exposure, easier technique, and potentially lower risk of neurovascular lesions, especially when posterior horns are involved.     

Arthroscopic evaluation of meniscal repairs after anterior cruciate ligament reconstruction and immediate motion

Sixty-six patients who had meniscal repair at the same time as an ACL reconstruction were followed-up with arthroscopy at an average of 12 months postoperatively. All patients underwent immediate postoperative range of motion from 20 degrees to 90 degrees and began partial weightbearing between the 1st and 3rd postoperative weeks. The rate of meniscal healing was classified as complete, partial, or failed. We statistically analyzed the effect of rim width, length of the tear, type of meniscus, age of patient, length of time between injury and repair, length of time between surgery and follow-up arthroscopy, and open versus arthroscopically assisted surgical procedure on the rate of meniscal healing. The overall results showed that 63 (80%) of the menisci completely healed, 11 (14%) partially healed, and 5 (6%) failed. The only factor that had a statistically significant impact on the rate of healing was rim width. Repairs in the outer one-third region had a higher incidence of healing (98% retained menisci) than those in the central one-third region (79% retained menisci, P less than 0.01). Still, the ability to repair a majority of central one-third meniscus tears that occur in the avascular zone (including flap tears and double longitudinal tears) suggest repair be considered when clinical grounds warrant preserving the meniscus. There were no complications, nor were there any deleterious effects from immediate knee motion or early weightbearing on the meniscal repairs. This allows an aggressive, immediate motion program to be followed with ACL reconstruction when concomitant meniscus repair is performed.     

MRI在半月板囊肿诊断中的应用

目的 探讨MRI在半月板囊肿临床诊断中的应用价值.方法 对18例经手术证实的膝关节半月板囊肿病例的MRI检查进行分析.结果 本组18例半月板囊肿发生于右膝11例,左膝7例.其中位于外侧半月板15例,内侧半月板3例.半月板囊肿的形态呈圆形、类圆形、三角形和不规则形,边界清楚,信号大致均匀,在T1加权像上为低或等信号,在T2加权像上为等或高信号,水激发序列图像上呈高信号.合并半月板损伤或退行性改变14例,其中Ⅲ°损伤9例.半月板囊肿起源于半月板前角15例,体部1例,后角2例.根据半月板囊肿与半月板的关系可以分为如下类型:半月板旁型14例,半月板内型1例,滑膜囊肿型2例.结论 半月板囊肿具有典型的影像学特征,MRI做为一种无创伤性影像学手段,可很好地显示半月板囊肿及其相关病变,为临床治疗提供全面的影像学信息.     

Discoid lateral meniscus and the frequency of meniscal tears

Objective. To use MRI to determine the incidence of discoid lateral menisci in a large study population, and to compare those patients with those without a discoid meniscus in order to assess the impact of a discoid lateral meniscus on the frequency of meniscal tears. Design and patients. Results of 1250 knee MRI studies were retrospectively reviewed. Using the criterion of three or more meniscal body segments on sequential sagittal images, 56 patients were found to have a discoid lateral meniscus. After exclusion of patients with prior knee surgery, 49 patients with a discoid lateral meniscus were compared with 1146 patients without a discoid meniscus. Patients were categorized as having tears of the medial meniscus, lateral meniscus, or both menisci. Results. In our study population, there was a 4.5% incidence of discoid lateral meniscus. Seventy-one percent of patients with a discoid lateral meniscus had one or more meniscal tears, compared with 54% of the comparison group (P=0.01). The frequency of solitary lateral meniscal tears in the discoid group was also higher than in the comparison group: 20%.versus 11% (P=0.03). The frequency of solitary medial meniscal tears and concomitant tears of both menisci were not significantly different between the two groups. Conclusions. The discoid lateral meniscus is an uncommon variant, but not as rare as once believed. Compared with the normal semilunar meniscus, the discoid lateral meniscus has a higher frequency of meniscal tears, and solitary tears of the lateral meniscus are more common in the discoid variant. The frequency of medial meniscal tears is not altered by the presence of a discoid lateral meniscus. Received: 17 August 2000 Revision requested: 11 December 2000 Revision received: 15 January 2001 Accepted: 16 January 2001     

MR of the knee: the significance of high signal in the meniscus that does not clearly extend to the surface

On MR images of the knee it is sometimes impossible to determine with confidence if a focus of high signal in the meniscus is confined to the substance of the meniscus or if it extends to involve the surface. This is a critical differentiation because the latter represents meniscal tears that can be found and treated at arthroscopy, whereas the former represents degeneration, tears, or perhaps normal variants that cannot be detected or treated arthroscopically. We make an equivocal diagnosis of a tear when it is difficult to decide if signal in a meniscus involves the meniscal surface. We studied MR scans of the knee in 142 consecutive patients for the presence of such equivocal tears. Their prevalence was 14% (20/142); 17 were in the posterior horn of the lateral meniscus and three were in the posterior horn of the medial meniscus. In 13 cases with arthroscopy/arthrotomy correlation, no tears were found. In one of the 20 patients in whom the meniscus was removed during arthroplasty, histologic examination of the meniscus showed separation of collagen bundles, which was caused by meniscal degeneration confined to the substance of the meniscus. These results suggest that a meniscal tear is unlikely when MR scans show a focus of high signal in a meniscus that does not unequivocally extend to involve the surface of the meniscus.     

Pericruciate meniscal cysts arising from tears of the posterior horn of the medial meniscus: MR imaging features that simulate posterior cruciate ganglion cysts.

OBJECTIVE: The purpose of this study is to describe MR imaging features of an unusual type of meniscal cyst arising from tears of the posterior horn of the medial meniscus in 10 patients. MATERIALS AND METHODS: Retrospective review of MR examinations of the knee was performed of 10 patients (nine men, one woman; mean age, 39 years) in whom evidence of a meniscal tear and a cyst-like structure around the posterior cruciate ligament (PCL) was seen. RESULTS: An oval mass with low signal intensity on T1-weighted MR images and increased signal intensity on T2-weighted MR images posterior to the PCL, simulating a PCL ganglion cyst, was seen in all 10 patients. A tear of the posterior horn of the medial meniscus was also seen in all patients. The sites of communication between the cyst and meniscal tear were observed in sagittal MR images in eight patients. Septation within the cyst and associated joint effusion were seen in eight and four patients, respectively. Arthroscopy in eight patients and transmeniscal needle drainage in the other two patients confirmed both the meniscal tear and the pericruciate meniscal cyst. CONCLUSION: Pericruciate meniscal cysts cause fluid collections posterior to the PCL, simulating a PCL ganglion cyst. Careful analysis of the posterior horn of the medial meniscus should be performed when a cyst-like structure is seen adjacent to the PCL.     

Contribution of thin-slice (1 mm) axial proton density MR images for identification and classification of meniscal tears: correlative study with arthroscopy

Objective To evaluate the diagnostic efficacy of thin-slice (1 mm) axial proton density-weighted (PDW) MRI of the knee for meniscal tear detection and classification. Methods We prospectively assessed pre-operative MR images of 58 patients (41 males, 17 females; age range 18-62 years) with arthroscopically confirmed meniscal tear. First, we evaluated the performance of the sagittal and thin-slice axial MR images for the diagnosis of meniscal tears. Second, we compared the correlation of tear types presumed from sagittal and axial MRI with arthroscopy and tear classification from axial MRI. Tears were classified on the sagittal plane and the axial plane separately. The diagnostic performance and tear classification were compared statistically with arthroscopy results, which is accepted as the standard of reference. Results 8 of 58 patients were removed from the study group because they had complex or degenerative tears. A total of 62 tears were detected with arthroscopy in 50 patients. On the sagittal images, sensitivity and specificity values were 90.62% and 70.37%, respectively, for medial meniscus tears and 72.73% and 77.14%, respectively, for lateral meniscus tears. The corresponding values for axial images were 97.30% and 84.00%, respectively, for medial meniscus tears and 95.65% and 80.50%, respectively, for lateral meniscus tears. There was no significant difference in tear classification between the arthroscopy results and the thin-slice axial PDW MRI results (p>0.05). Conclusion thin-slice axial PDW MRI increases the sensitivity and specificity of meniscal tear detection and especially classification, which is important for surgical procedure decisions.