Meniscal Width Research Articles

Magnetic-field induced flattening of evaporating ferro-nanofluid meniscus for enhanced cooling

This work envisages applying magnetic fields to flatten thin ferro-nanofluid film meniscus for enhanced heat transfer during evaporative cooling process. Experiments are conducted to examine the shape of the evaporating extended meniscus of ferro-nanofluid (Fe304 nanoparticles in water suspension 0.01% v/v) under axisymmetric vertical magnetic fields (∼10−2T) generated by solenoid placed below the heated substrate. The study includes measuring the thickness profile of the meniscus evaporating region using high nano-scale resolution reflectometry and theoretically interpreting meniscus shape in terms of flow and film heat transfer. Profile measurements reveal an increasing influence of magnetic fields in thinning of the adsorbed region and stretching of the transition region, which effectively reduce the thermal resistance across meniscus width. Data reduction based on thickness as well as the derived curvature profiles yields a high-pressure gradient driving flow along the evaporating thin film region. The results imply additional suction induced by disjoining pressure of thinner adsorbed layer which sustains replenishment of lost evaporative mass across a longer transition region interface. Subsequent heat transfer analysis reveals up to 156 % enhancement in overall heat flux and 101 % in average heat transfer with increasing magnetic field intensity. The findings establish proof of concept of applying magnetic field to augment film-based cooling.

Pediatric meniscus morphology varies with age: a cadaveric study.

In adolescent patients, meniscal tear injury can occur either in isolation (e.g., discoid lateral meniscus tears) or in association with other traumatic injuries including tibial eminence fracture or ACL tear. Damage to meniscal integrity has been shown to increase contact pressure in articular cartilage, increasing risk of early onset osteoarthritis. In symptomatic patients failing conservative management, surgical intervention via meniscus repair or meniscus transplant is indicated. The purpose of this study was to evaluate the radial dimensions of pediatric menisci throughout development. The hypothesis was that the average radial meniscus dimensions will increase as specimen age increases, and mean medial and lateral region measurements will increase at a linear rate. Seventy-eight skeletally immature knee cadaver specimens under age 12years were included in this study. The meniscal specimens were photographed in the axial view with ruler in the plane of the tibial plateau and analyzed using computer-aided design (CAD) software (Autodesk Fusion 360). Measurements were taken from inner to outer meniscus rims at five 45 degree intervals using the clockface as a reference (12:00, 1:30, 3:00, 4:30, 6:00), and total area of meniscus and tibial plateau was recorded. Generalized linear models were used to evaluate the associations of radial width measurements with age, tibial coverage, and lateral vs. medial meniscus widths. All radial width measurements increased significantly with specimen age (p ≤ 0.002), and all lateral-medial meniscal widths increased (p < 0.001). The anterior zones of the meniscus were found to increase at the slowest rate compared to other regions. Tibial plateau coverage was found to not significantly vary with age. Meniscus radial width and lateral-medial meniscus width are related to age. The anterior width of the meniscus varied least with age. Improved anatomic understanding may help surgeons more effectively plan for meniscus repair, discoid resection/saucerization/repair, and also support appropriate selection of meniscus allograft for transplantation.

The "Bankart knee": high-grade impression fractures of the posterolateral tibial plateau lead to increased translational and anterolateral rotational instability of the ACL-deficient knee.

The aim of this biomechanical cadaver study was to evaluate the effects of high-grade posterolateral tibia plateau fractures on the kinematics of anterior cruciate ligament (ACL)-deficient joints; it was hypothesized that, owing to the loss of the integrity of the osseous support of the posterior horn of the lateral meniscus (PHLM), these fractures would influence the biomechanical function of the lateral meniscus (LM) and consequently lead to an increase in anterior translational and anterolateral rotational (ALR) instability. Eight fresh-frozen cadaveric knees were tested using a six-degree-of-freedom robotic setup (KR 125, KUKA Robotics, Germany) with an attached optical tracking system (Optotrack Certus Motion Capture, Northern Digital, Canada). After the passive path from 0 to 90° was established, a simulated Lachman test and pivot-shift test as well as external rotation (ER) and internal rotation (IR) were applied at 0°, 30°, 60° and 90° of flexion under constant 200 N axial loading. All of the parameters were initially tested in the intact and ACL-deficient states, followed by two different types of posterolateral impression fractures. The dislocation height was 10mm, and the width was 15mm in both groups. The intraarticular depth of the fracture corresponded to half of the width of the posterior horn of the lateral meniscus in the first group (Bankart 1) and 100% of the meniscus width in the second group (Bankart 2). There was a significant decrease in knee stability after both types of posterolateral tibial plateau fractures in the ACL-deficient specimens, with increased anterior translation in the simulated Lachman test at 0° and 30° of knee flexion (p = 0.012). The same effect was seen with regard to the simulated pivot-shift test and IR of the tibia (p = 0.0002). In the ER and posterior drawer tests, ACL deficiency and concomitant fractures did not influence knee kinematics (n.s.). This study demonstrates that high-grade impression fractures of the posterolateral aspect of the tibial plateau increase the instability of ACL-deficient knees and result in an increase in translational and anterolateral rotational instability.

Reliability of MRI Interpretation of Discoid Lateral Meniscus: A Multicenter Study.

Discoid lateral meniscus (DLM) has a varied and complex morphology that can be challenging to assess and treat. Preoperative magnetic resonance imaging (MRI) is frequently used for diagnosis and surgical planning; however, it is not known whether surgeons are reliable and accurate in their interpretation of MRI findings when defining the pathomorphology of DLM. Surgeons experienced in treating DLM are able to reliably interpret DLM pathology using MRI. Cohort study (diagnosis); Level of evidence, 3. Knee MRI scans from 44 patients (45 knees) were selected from a pool of surgically treated patients with DLM. Five reviewers (fellowship-trained pediatric sports medicine surgeons) performed independent review of each MRI scan using the PRiSM Discoid Meniscus Classification. Inter- and intraobserver reliability of the rating factors-primary (width, height, presence of peripheral instability or tear) and secondary (location of instability or tear, tear type)-was assessed using the Fleiss κ coefficient, designed for multiple readers with nominal variables (fair reliability, 0.21-0.40; moderate, 0.41-0.60; substantial, 0.61-0.80; excellent, 0.81-1.00). Reliability is reported as κ (95% CI). Interobserver reliability in assessing most primary and secondary characteristics ranged from substantial (meniscal width) to moderate (peripheral instability, anterior instability, posterior instability, and posterior tear). Intraobserver reliability for most characteristics ranged from substantial (peripheral instability, presence of tear, anterior instability, posterior instability, and posterior tear) to moderate (meniscal width, anterior tear, and tear type). Notable exceptions were presence of tear, anterior tear, and tear type-all with fair interobserver reliability. Height had poor interobserver reliability and fair intraobserver reliability. Orthopaedic surgeons reliably interpret MRI scans using the PRiSM Discoid Meniscus Classification for the majority of DLM characteristics but vary in their assessment of height and presence and type of tear. MRI evaluation may be helpful to diagnose discoid by width and identify the presence of instability: 2 major factors in the decision to proceed with surgery. Arthroscopic evaluation should be used in conjunction with MRI findings for complete DLM diagnosis.

Biomechanical effects of medial meniscus radial tears on the knee joint during gait: A concurrent finite element musculoskeletal framework investigation.

The biomechanical variation in the knee during walking that accompanies medial meniscal radial tears stemming from knee osteoarthritis (OA) has not been explored. This study introduced a finite element musculoskeletal model using concurrent lower limb musculoskeletal dynamics and knee joint finite element analysis in a single framework and expanded the models to include knees with medial meniscal radial tears and total medial meniscectomy. The radial tears involved three locations: anterior horn, midbody, and posterior horn with grades of 33%, 50%, and 83% of the meniscus width. The shear and hoop stresses of the tear meniscus and tibial cartilage contact load, accompanying tears, and postmeniscectomy were evaluated during the stance phase of the gait cycle using the models. In the 83% width midbody tear group, shear stress at the end of the tear was significantly greater than in the intact meniscus and other tear groups, and the maximum shear stress was increased by 310% compared to the intact meniscus. A medial meniscus radial tear has a much smaller effect on the tibial cartilage load (even though in the 83% width tear, the cartilage/total load ratio increased by only 9%). However, the contact force on the tibial cartilage with total postmeniscectomy was increased by 178.93% compared with a healthy intact meniscus, and the peak contact pressure after meniscectomy increased from 11.94 to 12.45 MPa to 17.64 and 13.76 MPa, at the maximum weight acceptance and push-off, respectively. Our study shows that radial tears with larger medial meniscus widths are prone to high stress concentrations at the end of the tears, leading to the potential risk of complete meniscal rupture. Furthermore, although the tears did not change the cartilage load distribution, they disrupted the circumferential stress-transmitting function of the meniscus, thus greatly increasing the likelihood of the onset of knee OA. The significant increase in the tibial cartilage load with total postmeniscectomy indicates a potential risk of OA flare-ups. This study contributes to a better understanding of meniscal tear-induced OA biomechanical changes during human activities and offers some potential directions for surgical guidance of meniscectomies and the prophylaxis and treatment of OA.

Finite element study of a partial meniscectomy of a complete discoid lateral meniscus in adults.

Incidence of osteoarthritis and genu valgus is higher after partial meniscectomy of the discoid lateral meniscus. We aimed to provide a biomechanical reference for slowing the development of osteoarthritis and genu valgus after complete discoid lateral meniscus (CDLM) surgery. Computed tomography and magnetic resonance images of the knee were used to establish a finite element model of the knee. The discoid lateral meniscus model was cut at 2-mm intervals to obtain 10 lateral meniscus models of different widths (2-20mm). The instantaneous stress peak and knee valgus angle were obtained by finite element analysis under the same coaxial load. When the residual width of the lateral meniscus was greater than 12mm, the peak stress of the knee joint and angle of genu valgus did not significantly change from preoperative levels. The contact stress peak increased slightly as the width decreased from 12 to 8mm. When the width was reduced from 8 to 0mm, the contact stress peak increased significantly. For partial meniscectomy in CDLM patients, meniscus width of 8-10mm provides a better biomechanical environment. This may reduce risk of early knee degeneration and valgus from excessive meniscectomy in conventional surgery.

Comprehensive Arthroscopic Characterization of Discoid Meniscus Tears and Instability Using the PRiSM Discoid Meniscus Classification

The discoid meniscus is a congenital abnormality, with the vast majority occurring in the lateral meniscus. More commonly seen in pediatric populations, patients present with acute or chronic knee symptoms such as joint line pain, audible or palpable mechanical symptoms, and the inability to achieve terminal extension. The classic discoid classification system by Watanabe excludes anterior and horizontal instability and tearing that commonly occur with this pathology. A comprehensive classification, the Pediatric Research in Sports Medicine (PRiSM) Discoid Meniscus Classification, was developed to include these characteristics. To complement this classification system, we describe a complete arthroscopic examination of the discoid meniscus, assessing meniscal width, height, instability, and tearing. For thorough anterior assessment, the importance of medial portal viewing with lateral portal probing is highlighted. Assessment of the meniscus for tearing and instability should be performed before and after saucerization. Consistent use of a comprehensive classification system and a diagnostic arthroscopic exam will improve the understanding, treatment, and quality of research in the discoid meniscus.

Magnetic Resonance Image (Mri) Measurements of Lateral Discoid Meniscus (Ldm) in Pediatric Patients Match Adult Lateral Discoid Meniscus Definitions

Background:Commonly cited lateral discoid meniscus (LDM) imaging definitions are based upon adult MRI measurements: >70% tibial plateau coverage on the sagittal, >20% tibial plateau coverage on the coronal and >3 bowtie signs. This pathology more commonly presents in pediatric populations and it is unknown if these measurements apply to a pediatric population. Therefore, it is important to understand the Magnetic Resonance Image (MRI) measurements of LDM in a pediatric population.Hypothesis/Purpose:The purpose of this study is to define LDM measurements on MRI in a pediatric population. Authors hypothesize there is a wide variation in LDM characteristics on MRI.Methods:100 MRIs on LDM patients who are skeletally immature were evaluated and 91 included in this study. Demographics were recorded. Two study authors independently reviewed MRIs measuring meniscal height and width on sagittal and coronal images, tear presence, number of “bowties” on sagittal images, as well as tibial sagittal and coronal width. One study author repeated measurements a minimum of 4 weeks after initial review. Figure 1 describes each measurement. Statistical analysis was performed using fisher’s exact test for differences, as well as multinomial, linear and logistic regression models with clustered robust standard errors.Results:Average age at MRI was 12.3 ± 3.4 years, 51% male, 56% left knees. Table 1 reports gender comparison of MRI measurements. Table 2 reports gender comparison of bowtie sign and ratios of meniscal width to tibial width on coronal and sagittal images. Tears were reported in 72 MRIs (80%). Genders of patients with tears were not statistically different (Female: N=33; 73%, Male: N=39; 87%, p=0.16). Sagittal anterior (p=0.005) meniscal width, anterior to posterior meniscal width (p<0.001), and # of bowtie signs (p=0.043) were significantly associated with tear presence.Conclusion:MRI characteristics can aide in accuracy of LDM diagnosis. Pediatric patients with diagnosed discoid meniscus had >3 bowtie signs, >70% tibial plateau coverage on the sagittal, and >20% tibial plateau coverage on the coronal consistent with adult reported definitions of discoid meniscus.Figure 1.Description of MRI measurementsMeasurements of the lateral meniscus on the (a) sagittal plane and (b) coronal plane. Sagittal plane image in the mid-condylar slice shows: (4) total anterior to posterior meniscus distance, (5) anterior horn height, (6) posterior horn height, and (7) sagittal tibial width. Coronal plane image shows: (9) meniscus coronal width, (10) meniscus coronal height, and (11) coronal tibial width.Table 1.Gender comparison of MRI measurementsTable 2.Gender comparison of bowtie sign and ratios of meniscal width to tibial width

Reliability of Magnetic Resonance Imaging Interpretation of Lateral Discoid Meniscus: A Multicenter Study

Background:Lateral discoid meniscus (LDM) often present with complex morphology that can be challenging to assess and treat arthroscopically. Preoperative magnetic resonance imaging (MRI) is frequently used for diagnosis and surgical planning, however it is not known whether surgeons are reliable and consistent in their interpretation of MRI findings.Hypothesis/Purpose:We hypothesize that surgeons experienced in treating LDM are able to reliably interpret discoid pathology using MRI, with the exception of evaluating dynamic factors (i.e. instability).Methods:Forty five discoid meniscus MRI selected from a pool of surgical discoid meniscus cases were included in this review. Five reviewers (experienced pediatric sports medicine surgeons) who were not involved in the MRI selection process performed independent review of each MRI to determine discoid meniscus classification. More than 4 weeks later, a second reading was performed by 3 of the 5 reviewers. Interobserver and intraobserver reliability of the primary (width, presence of instability or tear) and secondary (location of instability or tear, tear type) rating factors was assessed using the Fleiss κ coefficient, designed for multiple readers with nominal variables (reliability: fair, 0.21–0.40; moderate, 0.41–0.60; substantial, 0.61–0.80; excellent, 0.81–1.00). Reliability is reported as κ (95% CI).Results:Interobserver reliability of assessment of meniscal width was substantial 0.67 (0.58-0.76), and intraobserver was moderate 0.52 (0.35-0.69). Assessment of presence of peripheral instability had moderate interobserver reliability 0.54 (0.45-0.63) and substantial intraobserver 0.61 (0.44-0.78). Presence of tear had fair interobserver reliability 0.39 (0.29–0.48) and substantial intraobserver 0.68 (0.51-0.85). When identifying location of instability or tear, interobserver reliability was moderate while intraobserver agreement was substantial for assessment of anterior instability (0.47 (0.37-0.56) and 0.68 (0.51-0.85), respectively); posterior instability (0.56 (0.47-0.65) and 0.62 (0.45-0.79), respectively); and posterior tear (0.41 (0.32-0.50) and 0.69 (0.52-0.86), respectively). The exception was identifying anterior tear, with fair interobserver reliability 0.33 (0.23-0.42) and moderate intraobserver 0.56 (0.39-0.73); Interobserver reliability was fair for tear type 0.34 (0.28-0.41) and intraobserver reliability moderate 0.55 (0.43-0.67).Conclusion:Orthopaedic surgeons experienced in the treatment of LDM vary from each other in their classification using MRI, especially with regard to assessment of meniscus tears. MRI evaluation may be helpful to diagnose discoid by width and identify presence of instability, two major factors in the decision to proceed with surgery. However, definitive treatment should be guided by a comprehensive arthroscopic evaluation.

Reliability of a New Arthroscopic Discoid Lateral Meniscus Classification System: A Multicenter Video Analysis

Background: The discoid lateral meniscus (DLM) is one of the most common congenital anomalies of the knee. The pathomorphology of DLM varies. Current classification systems are inadequate to describe the spectrum of abnormality. Purpose: A study group of pediatric orthopaedic surgeons from 20 academic North American institutions developed and tested the reliability of a new DLM classification system. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: After reviewing existing classifications, we developed a comprehensive DLM classification system. Four DLM features were evaluated: meniscal width, meniscal height, peripheral stability, and meniscal tear. Stepwise arthroscopic examination using anteromedial and anterolateral viewing portals was established for evaluating these features. Three senior authors who were not observers selected 50 of 119 submitted videos with the best clarity and stepwise examination for reading. Five observers performed assessments using the new classification system to assess interobserver reliability, and a second reading was performed by 3 of the 5 observers to assess intraobserver reliability using the Fleiss κ coefficient (fair, 0.21-0.40; moderate, 0.41-0.60; substantial, 0.61-0.80; excellent, 0.81-1.00). Results: Interobserver reliability was substantial for most rating factors: meniscal width, meniscal height, peripheral stability, tear presence, and tear type. Interobserver reliability was moderate for tear location. Intraobserver reliability was substantial for meniscal width and meniscal height and excellent for peripheral stability. Intraobserver agreement was moderate for tear presence, type, and location. Conclusion: This new arthroscopic DLM classification system demonstrated moderate to substantial agreement in most diagnostic categories analyzed.

Radial Width of the Lateral Meniscus at the Popliteal Hiatus: Relevance to Saucerization of Discoid Lateral Menisci

Background: A discoid lateral meniscus (DLM) is a congenital anomaly of the knee in which the lateral meniscus has an “O” shape and contains irregular, abnormal collagenous tissue. A DLM can cause mechanical symptoms and pain. Treatment of a symptomatic DLM is arthroscopic saucerization to reshape the meniscus to a more normal contour. Enough tissue must be removed to eliminate mechanical symptoms but not too much to create instability. The residual width of the meniscus is crucial at the popliteus hiatus because here the peripheral rim is unattached at the capsule. Reports in the literature recommend a residual width of 6 to 8 mm. Purpose/Hypothesis: The purpose of this research was to determine the width of the lateral meniscus at the popliteal hiatus in normal specimens. Our null hypothesis was that a residual width of 6 to 8 mm will be sufficient to approximate normal anatomy. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We made direct measurements of the radial width of the lateral meniscus from the outer rim at the popliteal hiatus to the inner edge in 19 specimens (age, 2-120 months.) We measured one 4-year-old specimen with a bilateral complete DLM. We also measured 39 digital images of specimens (age, 1-132 months) using ImageJ. Finally, we made direct arthroscopic measurements of 8 skeletally mature specimens. Results: The average width of specimens <3 years old was 5.5 mm. The average width of the 10-year-old specimens was 12 mm. The average width of the skeletally mature specimens was 16 mm. A 4-year-old DLM specimen measured 19 mm. Conclusion: We rejected our null hypothesis. Direct measurements suggest that a residual width of 6 to 8 mm is insufficient for children ≥8 years old. A width of at least a full centimeter approximates the normal for 8-year-olds and at least 15 mm for adolescents.

Arthroscopic Saucerization With Inside-Out Repair and Anterocentral Shift of a Discoid Lateral Meniscus With Retention of Adequate Volume of Residual Meniscus

AbstractPreservation of the meniscus has been shown to influence the progression of osteoarthritic changes in the knee. Discoid lateral meniscus (DLM) is classified on the basis of the presence and location of instability resulting from deficient capsular attachments. Recently, meniscal stabilization after saucerization was recommended in cases of DLM to preserve the meniscus shape and avoid the progression of osteoarthritis. However, it is difficult to identify the accurate resection volume and residual meniscal width during surgery, especially when there is an anterocentral shift of the DLM. This Technical Note describes an arthroscopic technique for an anterocentral shift of the DLM in which we highlight the resection point and confirm the methods of retaining an adequate volume of residual meniscus to restore and maintain the shape and function of the meniscus. Level of EvidenceLevel 1, Knee; Level 2, Meniscus.

Effect of 1.5 mm biter-width meniscectomy on cadaveric knee pressure, peak pressure, force, and contact area

This study investigated the immediate biomechanical effects of a biter-width partial medial meniscectomy. Small tears on the free edge of the meniscus are occasionally discovered during arthroscopic knee procedures. Removal of these tears often requires no more width than that of a biter from the edge. While past cadaveric partial meniscectomy studies have reported on the effects of meniscectomies from resection of one-third to three-quarters of meniscal width, the biomechanical sequelae of substantially smaller meniscectomies remain unknown. This study was performed to determine how single-biter-width meniscectomies affect the pressure distribution and peak pressure on the tibial plateau, as these parameters are correlated with increased likelihood of development of osteoarthritis. Eight cadaveric knees were instrumented with a thin-film pressure sensor underneath the menisci while retaining the major ligaments and most of the capsule. Knees were loaded to 1000 N at angles of flexion of 0, 15, 30, and 45 in normal tibio-femoral angles and in 7° of varus. Pressure, peak pressure, force and contact area were recorded. Afterwards, biter-width meniscectomies were performed, and measures repeated. There were significant changes in contact area at most flexion and tibio-femoral angles. There were no changes in the amount of force that was transmitted through the medial compartment. The overall pressure on the tibial plateau did not change in most knee conditions and peak pressure did not change significantly in any condition. The changes in contact area were consistent with our expectations. Similarly, the lack of change in force was also expected. However, the lack of significant changes in pressure and peak pressure represent findings indicating that a biter sized meniscectomy may have clinically insignificant effects on biomechanics.

Morphological Changes in the Residual Meniscus After Reshaping Surgery for a Discoid Lateral Meniscus

Background: Arthroscopic reshaping surgery is the first treatment option for a symptomatic discoid lateral meniscus (DLM) to preserve the peripheral rim. However, the degree of postoperative morphological change in the residual meniscus is unclear. Purpose/Hypothesis: The purpose of this study was to measure the meniscus after reshaping surgery for a DLM, to verify when the morphological change occurred, and to examine the related risk factors. The hypothesis was that the residual meniscal width would decrease throughout the postoperative course. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively reviewed the medical records of patients who underwent reshaping surgery for a symptomatic DLM and had undergone follow-up for ≥2 years. Magnetic resonance imaging (MRI) was routinely performed preoperatively and at 3, 6, 12, and 24 months postoperatively, and the width, height, and extrusion of the residual meniscus were measured. According to the width of the midbody on final MRI scans, we compared the preoperative and postoperative data for the preserved group (≥5 mm) and decreased group (<5 mm). The associated risk factors for a decreased meniscal width (<5 mm) of the midbody were analyzed on final MRI scans. Results: We included 61 knees of 54 patients in this study. The mean age at the time of surgery was 11.7 years. The intraobserver and interobserver reliabilities of the midbody width were 0.937 and 0.921, respectively. The width of the anterior horn, midbody, and posterior horn decreased significantly from 3 to 24 months after surgery (from 9.1 to 8.6 mm [P < .001], from 7.5 to 6.1 mm [P < .001], and from 9.5 to 8.9 mm [P = .001], respectively). Meniscal extrusion of the midbody did not change significantly (from 1.2 to 1.5 mm; P = .062). Overall, 46 knees (n = 20/32 in the preserved group and n = 26/29 in the decreased group) had longitudinal tears that required meniscal repair. Clinical outcomes did not differ significantly between the 2 groups. Multivariate logistic analysis showed that intrameniscal degeneration (odds ratio, 4.36; P = .023) significantly increased the risk of a decreased meniscal width. Conclusion: The width of the anterior horn, midbody, and posterior horn decreased significantly from 3 to 24 months after surgery. In particular, the average decrease rate of the midbody was 19%. No clinical difference was seen in patients with a decreased width and height or with peripheral extrusion. Increased intrameniscal signals on preoperative MRI scans were associated with an increased risk of a decreased meniscal width. Surgeons should consider this result to determine the amount of resection.

Diagnostic Value of Ultrasound in Children with Discoid Lateral Meniscus Using Either an Intracavitary Convex Array Probe or a Linear Array Probe

This prospective study aimed to assess the usefulness of an intracavitary convex array probe (ICAP) in visualizing the lateral meniscus (LM) and improving the diagnostic utility of ultrasound (US) when diagnosing or screening for discoid lateral meniscus (DLM) in children. We included 105 knees (66 patients) that had symptomatic or asymptomatic DLM. We extracted and retrospectively reviewed data regarding patient demographics, medical records, magnetic resonance imaging (MRI), ultrasonographic features and arthroscopic findings. The inner edge of the LM visualized using an ICAP was significantly clearer than that visualized using a linear array probe, and the difference was significant (p < 0.01). The edges were better visualized in patients aged <8 y than in those aged >8 y, and the difference was significant (p < 0.001). The average widths of the LM body using an ICAP and MRI were 19.85 ± 3.63 and 24.46 ± 4.94 mm, respectively, and the wider the meniscal width, the greater was the deviation between the US and MRI measurements, which were positively correlated (r = 0.612, p < 0.001). With the use of MRI measurements and an ICAP, meniscal widths in poorly visualized LMs were greater than those in clearly visualized LMs, but this difference was not significant (p = 0.161). US scans using an ICAP and MRI were highly consistent in assessing the shape of the menisci (κ = 0.849, p < 0.001). US scan using an ICAP is a non-invasive, convenient and low-cost modality for diagnosing or screening for DLM in the pediatric population, especially in children aged <8 y.

GROWTH OF THE PEDIATRIC KNEE MENISCUS: A CADAVERIC STUDY

Background:The menisci of the knee play a critical role in maintaining structural integrity, as well as in load bearing and shock absorption. In adolescent patients, meniscal tear is a very common sports injury, and is frequently associated with concomitant traumatic injuries including tibial eminence fracture or ACL tear. The incidence of pediatric meniscal tears is increasing, and anatomic studies to guide repair, saucerization and transplantation do not exist.Hypothesis/Purpose:This study’s purpose was to evaluate meniscus dimensions in the developing meniscus and provide anatomic parameters for repair, saucerization, resection, transplantation.Methods:From images of 29 dissected cadaveric knee specimens between 1 month and 132 months of age obtained on a copy stand (14 left knee, 15 right knee), we made direct length measurements from the inner to outer meniscus rim at 45 degree intervals (12, 1:30/10:30, 3:00/9:00, 4:30/7:30 o’clock, 6 o’clock) using Autodesk Fusion 360 software (Figure 1.1). We also measured width between the outer medial and lateral meniscus rims, as well as CT measurements of coronal and sagittal width of the tibial plateau using OsiriX DICOM software. Generalized linear models were used to evaluate the associations of meniscal length measurements with age, tibial width, and meniscal width measurements. All statistical analyses were completed with a two-sided level of significance of 0.05.Results:All radial length measurements were predicted to increase significantly with age (p < 0.01), as coronal tibial width increases (p < 0.05), and as lateral-medial meniscal width increases (p < 0.001) (Figure 1.2). Other than the lateral 3 o’clock measurement (p = 0.119), all radial measurements were predicted to increase significantly as sagittal tibial width increases (p < 0.05). The posterior zones of the medial meniscus (6:00, 4:30/7:30) were found to increase in radial length at a faster rate than the anterior zones. The anterior zones of the medial meniscus (12:00, 1:30/10:30) had the slowest rate of growth.Discussion/Conclusion:Meniscus radial length is related to age, tibial plateau width, and lateral-medial meniscus width. Radial dimensions from normal lateral menisci may allow the surgeon to obtain ideal size of resection, saucerization of discoid menisci. The growth of medial meniscus posterior zones is greater than the anterior zones. This may be attributed to increased posterior region load bearing which increases with ambulation in the developing child. Improved anatomic understanding may help surgeons plan for discoid resection/saucerization/repair, and also support appropriate selection of meniscus allograft for transplantation.Figure 1.1.Figure 1.2.

Changes in Medial Meniscal Three-Dimensional Position and Morphology As Predictors of Knee Replacement in Rapidly Progressing Knee Osteoarthritis: Data From the Osteoarthritis Initiative.

To assess whether quantitative changes in the meniscus predict progression from early knee osteoarthritis (OA) to knee replacement (KR). A nested case-control study was conducted among Osteoarthritis Initiative participants: all 35 case knees with baseline Kellgren/Lawrence (K/L) grade ≤2 that had KR between 36 and 60 months were matched 1:1 by age, sex, and baseline K/L grade to 35 control knees without subsequent KR. Quantitative 3-dimensional medial meniscus position and morphologic measures were determined from magnetic resonance imaging at the visit just before KR and 2 years before. Paired t-tests and case-control odds ratios (ORs, standardized per SD of change in controls) were used to compare changes between groups. Cases (52% women, age 65 ± 7 years, body mass index [BMI] 30 ± 4 kg/m2 , K/L grades 0/1/2: 5/8/22 participants, respectively) and controls (52% women, age 64 ± 7 years, BMI 30 ± 5 kg/m2 , K/L grades 0/1/2: 9/4/22 participants, respectively) were similar. Compared to control knees, KR case knees displayed longitudinal changes, specifically, a decrease in tibial plateau coverage, an increase in meniscal extrusion, and a decrease in meniscal width. The odds for KR increased with greater reduction in the percentage of tibial plateau coverage (OR 2.28 [95% CI confidence interval (95% CI) 1.43, 3.64]), a greater increase in maximal extrusion (OR 1.40 [95% CI 1.12, 1.75]), and a greater reduction of mean meniscal width (OR 2.01 [95% CI 1.23, 3.26]). The odds for KR increased with medial compartment cartilage thickness loss (OR 2.86 [95% CI 1.51, 5.41]) for comparison. Quantitative measures of meniscal position and morphology are associated with subsequent KR in knees with rapidly progressing knee OA. These findings show that structural changes of the meniscus are related to an important clinical and economic outcome of knee OA.

Variations of cross-sectional meniscal morphology between similar-sized menisci: implications on donor selection for meniscal allograft transplantation.

This study aimed to investigate the morphological variations in the cross-sectional anatomy of the meniscus between similar-sized matched menisci. Knee MRI of 329 patients with intact menisci were retrospectively reviewed, and the meniscal length (ML), meniscal width (MW), and cross-sectional dimensions (meniscal height and width) of the anterior, posterior horns, and the corpus were measured. Patients with similar-sized menisci who had less than 1mm difference in ML and MW were matched. 330 male-to-male medial menisci (MM), 623 male-to-male lateral menisci (LM), 82 female-to-female MM, 233 female-to-female LM, 176 cross-gender MM, and 265 cross-gender LM unique combination of ideally matched pairs (total: 1709) were generated. The disparity in the cross-sectional dimensions, absolute difference, and the paired percent differences was statistically analyzed. The ML and MW in all groups were statistically similar, with a predefined absolute difference of 1mm both for ML and MW (paired percent difference < 5%). The cross-sectional segmental meniscal dimensions were similar within all groups, but the paired percent differences showed high variations between a mean of 12.1-21.5% and up to 150.9%. The paired percent difference of MM in each segmental dimension was similar among different gender combinations. However, segmental paired percent differences of LM showed statistical differences in anterior horn width (AHW) (p: 0.001) and posterior horn width (PHW) (p: 0.001). In subgroup comparisons, the paired percent difference of AHW was higher in the female-to-female group compared to cross-gender (p: 0.023) and male-to-male groups (p: 0.001). The paired percent difference of PHW was smaller in the male-to-male group compared to female-to-female and cross-gender groups (p: 0.001 for both). Segmental cross-sectional anatomy showed wide variations despite strict matching in ML and MW. These variations were present in all gender combinations. The meniscal 3D shape is unique, but acceptable limits of similarity need further research. Retrospective study, Level III.

Radiographic Methods Are as Accurate as Magnetic Resonance Imaging for Graft Sizing Before Lateral Meniscal Transplantation

Background: Accurate allograft matching is deemed critical for meniscal transplantation; thus, precise measurements are essential to correctly calculate meniscal size. Several methods for meniscal sizing have been described, but there remains a discussion on which is the most accurate for the lateral meniscus. Purpose: To compare the accuracy of radiographic, anthropometric, and magnetic resonance imaging (MRI) methods of determining width and length of the lateral meniscus with actual dimensions after anatomic dissection. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen human cadaveric knees without any evidence of meniscal or ligamentous injury were primarily imaged using radiography and MRI and subsequently underwent dissection to assess the anatomic size of each meniscus. Four methods were used to predict the size of the lateral menisci: anthropometric, radiographic (Pollard and Yoon), and MRI. Absolute differences in length and width between actual and predicted sizes were determined. Results: The anatomic lateral meniscal width and length were 33.01 ± 4.25 mm (mean ± SD; range, 24.84-40.18 mm) and 31.41 ± 5.06 mm (range, 25.2-40.05 mm), respectively. Regarding width, the anthropometric method demonstrated an absolute difference from anatomic measurement significantly greater when compared with the Pollard technique and MRI (P = .002). Regarding length, the Pollard method presented an absolute difference significantly greater than all other techniques (P = .003). In terms of the ability to measure width and length, MRI accurately predicted meniscal size within 10% of the anatomic size in 65% of measurements, the Yoon method in 54%, and the Pollard method in 20% (P = .01). Radiographs tended to overestimate the true size of the lateral meniscus, while the anthropometric technique overestimated width in all specimens. Conclusion: This study demonstrated that MRI and the Yoon radiographic method are comparable in terms of accuracy for graft sizing before lateral meniscal transplantation. While MRI is useful, a contralateral MRI is required, which makes the Yoon radiographic method recommended given the ease and cost advantage. The original Pollard technique and the anthropometric method are not recommended. Clinical Relevance: Over- and undersizing of meniscal transplants has been implicated in graft failure. Therefore, increasing the reliability of preoperative meniscal measurements is deemed important for the success of meniscal allograft transplantation.

The postoperative shorter meniscal width was the risk factor of lateral meniscal extrusion in the middle portion for juvenile and adolescent knees with discoid lateral meniscus.

The study aim was to clarify the risk factors for postoperative meniscal extrusion in a middle portion in juvenile and adolescent knees with DLM. Forty-six patients with symptomatic DLM who underwent surgery were retrospectively assessed. Inclusion criteria were set as follows: (1) aged ≤ 17years with an open growth plate, (2) preoperative and postoperative follow-up MRI, and 3) reshaping surgeries comprising of saucerization alone or with meniscal repair. Average (95%CI) age during surgery, body mass index (BMI), and follow-up duration were 12years (11-13), 19.9kg/m2 (18.7-21.0), and 26.4months (19.5-33.3), respectively. Age, sex, sports activities, BMI, postoperative rehabilitation, preoperative shift of DLM by Ahn's classification, surgical procedures, postoperative meniscal width of all portions, and meniscal healing were analyzed. Postoperatively, eight knees in the no-extrusion group and 38 knees in the extrusion group were observed. In the univariate logistic regression analysis, shorter meniscal width in a middle portion (OR = 1.580, p = 0.006), shorter minimum width of all portions (OR = 1.674, p = 0.024), and meniscal healing (OR = 0.160, p = 0.028) were the risk factors for meniscal extrusion in a middle portion. Multiple logistic regression analysis demonstrated that shorter meniscal width in a middle portion was the risk factor. As the clinical relevance, to prevent postoperative meniscal extrusion of the middle portion with DLM, surgeons are necessary to pay attention to maintain the adequate meniscal width for juvenile and adolescent knees. III.