Meniscal Extrusion Research Articles

High Tibial Osteotomy With Medial Meniscal Posterior Root Tear Reconstruction Yields Improved Radiographic and Functional Outcomes and Healing Rates Compared With Osteotomy Alone

PurposeTo compare pre- and post-operative clinical and radiological outcomes between patients undergoing high tibial osteotomy (HTO) with medial meniscus posterior root tear (MMPRT) reconstruction using gracilis tendon graft versus those without reconstruction MMPRT. MethodsPatients with MMPRT who underwent HTO between January 2018 and December 2021 with minimum 2-year follow-up were included. All the patients were divided into 2 groups based on whether underwent meniscus root reconstruction with tendon graft, HTO alone (33 cases) and HTO with reconstruction MMPRT (21 cases). Clinical evaluation included Lysholm score, international knee documentation committee (IKDC) score, and visual analogue scale (VAS) score. The functional recovery and radiologically outcome of the knee were evaluated preoperatively and at the latest follow-up. Meniscus root healing rates and medial meniscal extrusion (MME) according to the second MRI were compared between the two groups at the latest follow-up. ResultsThe results showed a statistically significant improvement in the postoperative Lysholm score, IKDC score, and VAS score in both groups at the latest follow-up (P<0.001). The analysis of Minimal Clinically Important Difference (MCID) for postoperative outcomes revealed that the percentage of patients who reached MCID thresholds was 100% for Lysholm, 100% for IKDC, and 100% for VAS in the HTO with reconstruction MMPRT group. In comparison, the percentages were 87.9% for Lysholm, 90.9% for IKDC, and 100% for VAS in the HTO alone group. Additionally, compared with the HTO alone group, the HTO with medial meniscus posterior root reconstruction using gracilis tendon graft significantly improved the meniscus root healing rates (Complete healing 85.7% vs. 45.4%, 95%CI: 0.003-0.007, P=0.001) and functional recovery (P<0.005 ) at the final follow-up. Additionally, the HTO with reconstruction MMPRT had a significantly better change in K-L grade (improved knees K-L grade: 10/21 vs. 6/33, P=0.033) and MME (2.1±1.0mm vs. 3.1±1.6mm, 95%CI: 0.3-1.7, P=0.007) compared to the HTO alone group. ConclusionsHTO with reconstruction of the meniscal root using a tendon graft resulted in improved radiographic and patient-reported outcomes as well as improved healing rates compared to the HTO alone.

Joint line convergence angle is the most associated alignment factor with the severity of medial knee osteoarthritis.

The purpose of this study was to evaluate the relationship between the joint line convergence angle (JLCA) and the severity of medial knee osteoarthritis (OA). We hypothesise that JLCA is the most associated factor with the severity of medial knee OA. This retrospective study included a total of 202 knees that underwent either high tibial osteotomy or medial meniscus repair/partial resection. Kellgren-Lawrence grade and hip-knee-ankle angle (HKAA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA) and JLCA were assessed from preoperative radiographs. Medial meniscus extrusion (MME) was measured using preoperative magnetic resonance imaging. The International Cartilage Research Society (ICRS) grade on the medial femoral condyle and medial tibial plateau were also assessed. The relationships between JLCA and Kellgren-Lawrence grades and MME and ICRS grades were analysed using Spearman's correlation test and regression analysis. The JLCA was correlated with the Kellgren-Lawrence grade (R = 0.765, p < 0.001), MME (R = 0.638, p < 0.001), ICRS grade on the MFC (R = 0.586, p < 0.001) and the MTP (R = 0.586, p < 0.001). Regression analysis showed that age (p = 0.002) and JLCA (p < 0.001) were associated with Kellgren-Lawrence grade. Furthermore, JLCA was related to ICRS grade on the MFC (p < 0.001) and MTP (p < 0.001). The JLCA, reflecting radiological severity, meniscus status, and cartilage lesion, was the most associated alignment parameter in the severity of medial knee OA. The JLCA may be beneficial for quantitative assessment of medial knee OA. Level III, retrospective cohort study.

The association of the medial meniscus covering ratio with knee cartilage thickness at 15 medial compartment subregions as found by three-dimensional analysis using MRI.

The correlation of cartilage thickness measured by three-dimensional (3D) magnetic resonance imaging (MRI) and the medial meniscal coverage ratio (MMCR), which presented pathology of the medial meniscus extrusion (MME) in 3D MRI, has not yet been elucidated. The study's purpose was to retrospectively verify whether the average cartilage thickness calculated by the automatic MRI 3D analysis system for each subregion was correlated with MMCR. A total of 60 patients underwent medial meniscus repair or high tibial osteotomy to treat their medial knee osteoarthritis. Cartilage thickness and MMCR were automatically calculated using 3D MRI software. The MMCR was defined as the ratio of the area covered by the meniscus within the medial tibial cartilage area to the total medial tibial cartilage area. The association between MMCR and the average cartilage thickness at 15 subregions in the medial femoral condyle (MFC) and medial tibial plateau (MTP) was evaluated using Spearman's rank correlation coefficient. Kellgren-Lawrence grade exhibited a negative correlation with MMCR and a positive correlation with MME width. Cartilage thickness in the MTP had a moderately positive correlation with MMCR at four subregions and a weakly positive correlation at another subregion. Cartilage thickness in the MFC showed a moderately positive correlation with MMCR at five subregions and a weakly positive correlation at one subregion. Cartilage thickness calculated by automatic MRI 3D analysis system had a positive correlation with MMCR for all subregions of the anterior and middle subregions in the MFC and for five regions of nine subregions of the anterior and middle subregions in the MTP. Level II, cross-sectional study (diagnosis).

Preoperative Medial Meniscus Extrusion on Magnetic Resonance Imaging Is Associated With a Tendency Toward Varus Shifting of Open-Wedge High Tibial Osteotomy: A Minimum 5-Year Follow-Up Study

PurposeTo investigate serial changes in postoperative alignment over 5 years after open-wedge high tibial osteotomy (OWHTO) and to identify risk factors associated with alterations in the postoperative weight-bearing line WBL ratio. MethodsPatients who underwent OWHTO during 2011–2017 were retrospectively reviewed. Inclusion criteria were (1) follow-up duration ≥5 years and (2) serial postoperative long-standing hip-to-ankle radiographs to evaluate alignment alterations. The WBL ratio was measured preoperatively and at 3 months, 6 months, 1 year, and 5 years postoperatively to evaluate serial changes. Alterations in the WBL ratio were analyzed using a linear mixed model, considering potential risk factors including International Cartilage Repair Society (ICRS) grades of each compartment, and medial meniscus extrusion (≥3 mm). Clinical outcomes were assessed using the Knee Society (KS) objective and functional scores, and the correlations between clinical outcomes and alignment alteration were examined. ResultsA total of 78 knees were investigated. During the study period, the overall WBL ratio decreased by 5.5 ± 7.2%, signifying varus shifting, from 58.6 ± 11.5% at 3 months post-surgery to 51.5 ± 12.7% at 5 years post-surgery. Based on univariate regression analyses, ICRS grade of the medial compartment and medial meniscus extrusion were included in a linear mixed model regarding alignment alteration. The model identified medial meniscus extrusion as a significant risk factor after adjusting for time (p <0.001). Medial meniscus extrusion also had a significant interaction with time (p <0.001), indicating greater alignment alteration in cases of medial meniscus extrusion. The extrusion was noted in 68 out of 78 knees. ConclusionIn the midterm following OWHTO, the overall alignment had a tendency toward varus shifting. A linear mixed model found that preoperative medial meniscus extrusion on magnetic resonance imaging is associated with the tendency.

High Tibial Osteotomy Alone Does Not Decrease Medial Meniscus Extrusion in the Setting of Medial Meniscus Posterior Root Tear: A Cadaveric Study

PurposeThis study investigated whether inducing valgus alignment and shifting the load laterally through high tibial osteotomy (HTO) alone decreases the extent of medial meniscus extrusion (MME) in the setting of medial meniscus posterior root tear(MMPRT) using ultrasound evaluation. MethodsEight fresh-frozen human cadaveric knee specimens were tested using a six-degree-of-freedom robotic testing system and ultrasound. Each specimen was tested in five conditions: (1) intact, (2) MMPRT, (3) medial meniscus repair (MMR), (4) combined medial open-wedge HTO + MMR, and (5) HTO + MMPRT. Measurements were obtained over the medial collateral ligament (MCL, central image) and posterior to the MCL (posterior image) with a 250 N axial load at 0°, 30°, and 90° of knee flexion. Statistical analysis was performed using a two-factor repeated-measures ANOVA. ResultsMME was significantly greater in HTO + MMPRT(0°: 2.44 ± 0.41mm, 30°: 2.47 ± 0.37mm, 90°: 2.41 ± 0.28mm) than HTO + MMR in central images (mean difference +0.83 mm, p < .001). No significant difference was found between HTO + MMPRT and MMPRT in MME . MMR had significantly less MME than MMPRT (mean difference -0.58mm, p < .001, posterior image at 0°and central image at 90°, p=.002). HTO + MMR showed significantly less MME than MMR alone at 30° and 90° knee flexion in central image (30°: -0.38 ± 0.05mm, 90°: -0.45 ± 0.06mm, p < .001) and 90° knee flexion in posterior image (-0.38 ± 0.08mm, p = .004). ConclusionHTO alone did not decrease MME in the setting of MMPRT, while MMR alone decrease MME after MMPRT. Additionally, HTO + MMR decreases MME aftrer MMPRT compared to MMR alone, although the clinical significance was uncertain. Clinical RelevanceThe findings of this study provide clinicians with valuable insights for improving MME. HTO alone does not decrease MME in cases of MMPRT.

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

(I) Characterize the demographics and clinical features of patients with meniscal root tears (MRT); (II) analyze the morphology, extent, and grade of MRT on MRI; (III) evaluate associated abnormalities on imaging; and (IV) evaluate the associations between imaging findings, demographics, clinical features, and joint structural abnormalities. A search was performed to identify meniscal root tears. Age, sex, BMI, and pain were recorded. Knee radiographs and MRI were reviewed. Presence, grade and morphology of MRT, meniscal extrusion, insufficiency fractures, as well as joint structural abnormalities were scored. For goals (I), (II), and (III), tabulations for categorical variables and mean for continuous variables were computed. MRT findings variables were described using percentages. For goal (IV), adjusted linear and logistic regression were employed. Ninety-six patients with a mean age of 56.6years (69 females) and mean BMI of 28.9kg/m2 were included; 88 of the MRT were located at the posterior horn of the medial meniscus (PHMM), and 82% were radial tear. The mean tear diameter was 3.8mm, and 78/96 tears presented with meniscal extrusion. Nineteen patients presented with subchondral insufficiency fracture (SIF), which was significantly associated with the gap of the tear (p = 0.001) and grade of the meniscal root lesion (p = 0.005). MRT typically found in middle-aged to older overweight and obese women. Lesions were mostly radial tears and located at PHMM and were frequently associated with meniscal extrusion and SIF. Moreover, the presence of SIF was significantly associated with the gap width and grade of root tear.

A Novel Ultrasound Method of Evaluating Dynamic Extrusion of Lateral Meniscus in Healthy Population: Different Patterns of Dynamic Extrusion Revealed Between Lateral and Medial Meniscus.

To establish a reliable ultrasound (US) method of evaluating dynamic extrusion of lateral meniscus in healthy population, and to investigate the pattern of dynamic meniscus extrusion (ME) in lateral meniscus under loading conditions. The lateral ME was examined via US method in unloaded, double-leg standing, and single-leg standing positions. Two different US measurement methods were compared to the magnetic resonance imaging (MRI) results to determine the optimal measurement methods. The US results obtained by different researchers were tested for interobserver consistency and the results obtained by the same researcher on two separate days were tested for intraobserver consistency. The patterns of dynamic extrusion were compared between medial and lateral sides. A total of healthy 44 volunteers were included in the study, with 86 knees assessed by US, and 25 knees evaluated by MRI. The US evaluation of dynamic lateral ME demonstrated excellent interobserver and intraobserver reliability. The US measurements using method A were consistent with the MRI results with no significant difference (P = .861, intraclass correlation coefficient [ICC] = 0.868), while method B underestimated the lateral ME compared to MRI (P = .001, ICC = 0.649). Lateral ME decreased slightly from unloaded (1.0 ± 0.8 mm) to single-leg standing position (0.8 ± 0.8 mm), whereas medial ME increased significantly in both double-leg and single-leg standing positions (2.4 ± 0.7 mm, 2.6 ± 0.7 mm). A novel US evaluation method of lateral ME was established with reliable and accurate results compared to the MRI. Lateral ME in healthy populations decreased slightly as the loadings increased, which was different from the pattern of dynamic extrusion in medial meniscus.

Association between medial meniscal extrusion and knee structural progression in adults with symptomatic knee osteoarthritis - a prospective cohort study.

To examine the association between medial meniscal extrusion and structural progression in adults with symptomatic knee osteoarthritis (OA). This prospective cohort study examined 176 participants with symptomatic knee OA recruited into a randomised controlled trial. The participants underwent magnetic resonance imaging (MRI) of the study knee at baseline and approximately 2years later. Meniscal extrusion, tibial cartilage volume, and tibiofemoral bone marrow lesions (BMLs) were measured from MRI using validated methods. Participants with medial meniscal extrusion ≥ 3mm had a higher prevalence of lateral tibiofemoral BMLs at baseline (OR = 2.21, 95% CI 1.06-4.61, p = 0.035), and those with medial meniscal extrusion 2-3mm had a higher likelihood of lateral BML worsening over 2years (OR = 3.76, 95% CI 1.35-10.52, p = 0.011), compared with those with medial meniscal extrusion < 2mm. Participants with stable medial meniscal extrusion had a lower likelihood of lateral BML worsening compared with those with regression of medial meniscal extrusion over 2years (OR = 0.20, 95% CI 0.07-0.56, p = 0.002). There were no associations between medial meniscal extrusion and tibial cartilage volume or medial tibiofemoral BMLs. Our study showed associations between medial meniscal extrusion and baseline prevalence and worsening over 2years of lateral tibiofemoral BMLs in people with symptomatic knee OA. Although the reasons for the lack of associations in the medial compartment are not clear, our results suggest a role of medial meniscal extrusion in predicting structural progression in lateral knee OA and that meniscal extrusion might be a potential target in the management of knee OA.

Association between progression of knee osteoarthritis pathology and gait changes over two years: Data from the IMI-APPROACH cohort

ObjectiveGait alterations in knee osteoarthritis (OA) patients are potentially related to structural progression of joint tissues, of which some are modifiable. The current objective was to determine whether progression in individual OA pathologies is related to gait kinematic parameters in knee OA patients, and whether these changes are influenced by pain. DesignRange of motion (ROM) during gait, joint tissue pathologies and morphology from index knee radiographs and MRI, and WOMAC pain were collected at baseline and at two-years in the IMI-APPROACH clinical knee OA cohort. Principal component (PC) analysis was performed on two-year change in gait parameters; the resulting (first) PC was compared between progressors and non-progressors for each structural parameter. When the PC indicated differences between groups (p < 0.1), individual gait parameters were compared for that structural outcome. Statistically significant differences in individual gait parameters were corrected for pain change. Results191 patients (age 66.5 ± 6.7; BMI 27.5 ± 4.8; 76 % female; 51 % Kellgren-Lawrence grade ≥2) were analyzed. The gait change PC differed between progressors and non-progressors for meniscal extrusion, bone marrow lesions (BMLs), and patellofemoral cartilage lesions. Further, meniscal extrusion progressors showed significantly more knee ROM and calf ROM decrease, BML progressors worsened more in thigh ROM, and patellofemoral cartilage lesion progressors improved in knee ROM. BML results were no longer significant after pain change adjustment (p = 0.054). ConclusionsMeniscal extrusion and BML progression are associated with gait worsening, though for BMLs the effect might be influenced by pain.

Management of Meniscus Pathology with Concomitant Anterior Cruciate Ligament Injury.

The purpose of this review is to summarize current clinical knowledge on the prevalence and types of meniscus pathology seen with concomitant anterior cruciate ligament (ACL) injury, as well as surgical techniques, clinical outcomes, and rehabilitation following operative management of these pathologies. Meniscus pathology with concomitant ACL injury is relatively common, with reports of meniscus pathology identified in 21-64% of operative ACL injuries. These concomitant injuries have been associated with increased age and body mass index. Lateral meniscus pathology is more common in acute ACL injury, while medial meniscus pathology is more typical in chronic ACL deficiency. Meniscus tear patterns associated with concomitant ACL injury include meniscus root tears, lateral meniscus oblique radial tears of the posterior horn (14%), and ramp lesions of the medial meniscus (8-24%). These meniscal pathologies with concomitant ACL injury are associated with increased rotational laxity and meniscal extrusion. There is a paucity of comparative studies to determine the optimal meniscus repair technique, as well as rehabilitation protocol, depending on specific tear pattern, location, and ACL reconstruction technique. There has been a substantial increase in recent publications demonstrating the importance of meniscus repair at the time of ACL repair or reconstruction to restore knee biomechanics and reduce the risk of progressive osteoarthritic degeneration. Through these studies, there has been a growing understanding of the meniscus tear patterns commonly identified or nearly missed during ACL reconstruction. Surgical management of meniscal pathology with concomitant ACL injury implements the same principles as utilized in the setting of isolated meniscus repair alone: anatomic reduction, biologic preparation and augmentation, and circumferential compression. Advances in repair techniques have demonstrated promising clinical outcomes, and the ability to restore and preserve the meniscus in pathologies previously deemed irreparable. Further research to determine the optimal surgical technique for specific tear patterns, as well as rehabilitation protocols for meniscus pathology with concomitant ACL injury, is warranted.

MR imaging methods to study meniscal position and mechanics

ObjectiveMeniscal mechanics have been studied widely due to the high prevalence of meniscal injuries and their strong association with knee degeneration. Computational models and cadaver studies have contributed to our understanding of the menisci but require assumptions to extrapolate to living people. Imaging modalities provide the ability to make key measurements in vivo. In particular, magnetic resonance imaging (MRI) provides the three-dimensional (3D) visualization of the menisci required to make important measurements related to mechanical function. This mini review summarizes MR approaches that have been used to make measurements related to meniscal mechanics, including morphology, position, movement, shape, and extrusion. DesignA literature search was performed using PubMed and Google Scholar, with search terms including “meniscus” and “MRI” in combination with “mechanics”, “position”, “shape”, “movement”, “size”, “loaded”, and “unloaded”. Articles were manually reviewed and selected by consensus between the authors as constituting the most important examples of work required to illustrate the breadth of measurement and imaging approaches used in research on meniscal function. ResultsMRI has been used for quantitative 3D analyses of the morphology and position of the menisci. Morphological analyses included measurements of meniscal volume, thickness, width, and bulging. Positional analyses included measurements of the overlap between the meniscal surface and tibial joint surface, the amount of extrusion, and the percentage of joint surface area and meniscal area that were covered or uncovered. Open MR scanners have been used to measure the movement of the menisci from full extension to deep flexion. MR compatible loading devices have been used to study the effect of loading on meniscal morphology and extrusion. Studies using these methods have found that there are differences in meniscal morphology between healthy and osteoarthritic participants, that the lateral meniscus and anterior horns have greater movement throughout flexion, and that meniscal extrusion increases under load. ConclusionsMRI has improved our insight into meniscal mechanics. Simulated weightbearing, open imaging through the range of knee flexion, and image processing to yield 3D measurements have all contributed to this progress. These approaches have strong potential to explore clinically motivated research questions related to meniscal mechanics.

The mediating role of synovitis in meniscus pathology and knee osteoarthritis radiographic progression

Meniscus pathologies (damage, extrusion) and synovitis are associated with knee osteoarthritis (KOA); however, whether synovitis mediates the relationship between meniscus pathologies and KOA radiographic progression remains unclear. We conducted an observational study in the Osteoarthritis Initiative (OAI) cohort, with a 48-month follow-up. Meniscus pathology and synovitis were measured by MRI osteoarthritis knee score (MOAKS) at baseline and 24 months, and a comprehensive synovitis score was calculated using effusion and Hoffa synovitis scores. The knee osteoarthritis radiographic progression was considered that Kellgren–Lawrence (KL) grade and joint space narrowing (JSN) grade at 48 months were increased compared to those at baseline. This study included a total of 589 participants, with KL grades mainly being KL1 (26.5%), KL2 (34.1%), and KL3 (30.2%) at baseline, while JSN grades were mostly 0 at baseline. A logistic regression model was used to analyze the relationship between meniscus pathology, synovitis, and KOA progression. Mediation analysis was used to evaluate the mediation effect of synovitis. The average age of the participants was 61 years old, 62% of which were female. The medial meniscus extrusion was longitudinally correlated with the progression of KL (odds ratio [OR]: 2.271, 95% confidence interval [CI]: 1.412–3.694) and medial JSN (OR: 3.211, 95% CI: 2.040–5.054). Additionally, the longitudinal correlation between medial meniscus damage and progression of KOA (OR: 1.853, 95% CI: 1.177–2.941) and medial JSN (OR: 1.655, 95% CI: 1.053–2.602) was significant. Synovitis was found to mediate the relationship between medial meniscus extrusion and KL and medial JSN progression at baseline (β: 0.029, 95% CI: 0.010–0.053; β: 0.022, 95% CI: 0.005–0.046) and beyond 24 months (β: 0.039, 95% CI: 0.016–0.068; β: 0.047, 95% CI: 0.020–0.078). However, we did not find evidence of synovitis mediating the relationship between meniscal damage and KOA progression. Synovitis mediates the relationship between medial meniscus extrusion (rather than meniscus damage) and KOA progression.

Reduced physiological extrusion of the medial meniscus in axial load-bearing condition in anterior cruciate ligament deficiency.

In this study, ultrasonography was used to measure medial meniscus (MM) extrusion under weight-bearing and nonweight-bearing conditions in both anterior cruciate ligament (ACL)-deficient and ACL-intact knee groups. This study aimed to determine the possible differences between these groups with an eventual impact on meniscal tears in ACL-deficient knees. A total of 107 patients who underwent ACL reconstructive surgery between June 2022 and April 2023 were enroled. After applying exclusion criteria, 37 patients met the conditions for inclusion in the study and formed the ACL deficiency group (Group D). Of the 141 patients presenting to an outpatient clinic who agreed to have ultrasonography conducted on their nondiscomforting contralateral knee, 37 patients matched for age, sex, hip-knee-ankleangleand body mass indexwith Group D patients were selected for the ACL intact group (Group I). Ultrasonography was used to measure MM extrusion in weight-bearing and nonweight-bearing conditions for all participants. Seventy-four patients were included in the study (n = 37 per group). The supine position showed an MM extrusion of 1.2 ± 0.7 mm in Group I and 1.2 ± 0.7 mm in Group D (not significant). In the standing position, MM extrusion measured 2.0 ± 0.6 mm in Group I and 1.3 ± 0.8 mm in Group D. The difference in extrusion (Δextrusion) between the two positions was 0.8 ± 0.6 in Group I and 0.1 ± 0.2 in Group D, with statistical significance (p < 0.01). A consistent reduction in MM extrusion during weight-bearing was observed in patients with ACL deficiency, irrespective of the duration of ACL deficiency, age, sexand BMI. ACL deficiency did not significantly impact MM extrusion during nonweight-bearing conditions; however, less MM extrusion was observed in response to axial loading conditions. These findings indicate altered MM biomechanics due to increased anterior-posteriormeniscal motion and rotational instability after ACL injury. Level III.

High incidence of medial meniscus root/radial tears and extrusion in 253 patients with subchondral insufficiency fractures of the knee.

The demographic and radiological risk factors of subchondral insufficiency fractures of the knee (SIFK) continue to be a subject of debate. The purpose of this study was to associate patient-specific factors with SIFK in a large cohort of patients. Inclusion criteria consisted of patients with SIFK as verified on magnetic resonance imaging (MRI). All radiographs and MRIs were reviewed to assess characteristics such as meniscus tear presence and type, subchondral oedema presence and location, location of SIFK, mechanical limb alignment, osteoarthritis as assessed by Kellgren-Lawrence grade and ligamentous injury. A total of 253 patients (253 knees) were included, with 171 being female. The average body mass index (BMI) was 32.1 ± 7.0 kg/m2. SIFK was more common in patients with medial meniscus tears (77.1%, 195/253) rather than tears of the lateral meniscus (14.6%, 37/253) (p < 0.001). Medial meniscus root and radial tears of the posterior horn were present in 71.1% (180/253) of patients. Ninety-one percent (164/180) of medial meniscus posterior root and radial tears had an extrusion ≥3.0 mm. Eighty-one percent (119/147) of patients with SIFK on the medial femoral condyle and 86.8% (105/121) of patients with SIFK on the medial tibial plateau had a medial meniscus tear. Varus knees had a significantly increased rate of SIFK on the medial femoral condyle in comparison to valgus knees (p = 0.016). In this large cohort of patients with SIFK, there was a high association with medial meniscus root and radial tears of the posterior horn, meniscus extrusion ≥3.0 mm as well as higher age, female gender and higher BMI. Additionally, there was a particularly strong association of medial compartment SIFK with medial meniscus tears. As SIFK is frequently undiagnosed, identifying patient-specific demographic and radiological risk factors will help achieve a prompt diagnosis. Level IV.

The Usefulness of Posterior Shiny Corner Lesions in the Early Diagnosis of Medial Meniscus Posterior Root Tears.

Posterior shiny corner lesions (PSCLs) have been reported to be useful for the early diagnosis of medial meniscus posterior root tears (MMPRTs) in surgical patients. However, the usefulness of PSCLs in outpatients, particularly regarding the optimal timing of magnetic resonance imaging (MRI) examinations after injury, remains unknown. We hypothesized that PSCLs would normally be observed in patients with MMPRTs within one month of injury. This study included 144 patients with knee pain who visited our hospital between January 2021 and May 2023. MRI findings within and after one month were examined. Fisher's exact test was performed for PSCLs, cleft signs, ghost signs, radial tear signs, bone cysts, and medial meniscus extrusion (MME), which are findings used for the diagnosis of MMPRTs. Time-dependent receiver operating characteristic (ROC) curve analysis was performed for each MRI finding. A binomial logistic regression analysis was performed for age, sex, PSCL, ghost sign, and MME. PSCLs were observed on 82.6% of the MRI scans within one month, but the positivity rate decreased after one month. After one month, a high percentage of patients had cleft signs and ghost signs. The results of a time-dependent ROC curve analysis showed that the PSCL had better diagnostic ability than the cleft sign, ghost sign, radial tear sign, and MME at a relatively early stage. Additionally, the area under the curve (AUC) of PSCL peaks around 35 days and then declines, reaching 0.8 or less around 40 days. On the other hand, the AUC of the cleft sign and ghost sign began to increase around 30 days after injury, and it exceeded 0.8 after approximately 100 days. The results of the binomial logistic regression analysis revealed significant PSCLs and ghost signs. Independent associations between the PSCL, or ghost sign, and the MMPRT were demonstrated. This study suggests that PSCLs have a superior diagnostic capability for MMPRT during the early stages of injury compared with other MRI findings in outpatients. In particular, PSCLs have a high positivity rate within one month after injury and a high diagnostic capacity up to 40 days after injury.

Review of the Development of Meniscus Centralization.

With an aging population, extending healthy life expectancy is a global challenge. Maintaining healthy knee joint function is one of the essential factors to preserve the ability to walk and extend healthy life expectancy. Meniscus centralization was introduced in 2012 as a procedure for meniscus extrusion, one of the causes of knee osteoarthritis (OA). Initially, it was performed only for lateral meniscus (LM) extrusion, and favorable 2-year results were reported in 2016. Gradually, basic studies supporting the effectiveness of meniscus centralization have been reported, and it has also been performed for medial meniscus (MM) extrusion, with some positive results reported. Although the surgical procedures vary among the institutions, the basic concept is to reattach the loosened meniscotibial ligament to the edge of the tibial plateau to re-tension it. This review will discuss the history of development and the current status of meniscus centralization. Current research shows that meniscus centralization is not performed in isolation but is often used as an augmentation along with the conventional repair of meniscus injuries, particularly posterior root tears. Biomechanical studies demonstrated that MM centralization with a posteromedial anchor can better restore meniscus function. Despite its relatively short publication history of just over ten years, meniscus centralization has shown potential as a treatment to curb the progression of knee OA and extend a healthy life. While more evidence is needed, this conclusion underscores the promising role for meniscus centralization, making it a topic of significant interest for knee surgeons and researchers.

More than 3 mm of preoperative medial meniscal extrusion is identified as a key risk factor for varus progression in limb alignment after arthroscopic repair of medial meniscus posterior root tear.

To investigate the risk factors for varus progression after arthroscopic medial meniscal posterior root tear (MMPRT) repair and to compare the clinical outcomes between two groups: one with more varus progression and the other with less varus progression. Patients who underwent isolated arthroscopic repair of MMPRT between 2015 and 2020 were enroled, and 2-year follow-up data were collected. Participants were categorized into two groups based on preoperative values of the weight-bearing line (WBL) ratio: group A with <5.9% increase and group B with ≥5.9% increase. Various factors, including demographic features and radiological findings, were analysed and compared between the two groups. Intra-meniscal signal intensity, meniscal healing, medial meniscal extrusion (MME), and articular cartilage grade were assessed preoperatively and 1-year postoperatively using coronal magnetic resonance imaging. The final cohort consisted of 34 patients in group A and 46 in group B, with a mean age of 55.8 ± 11.2 and 59.8 ± 6.6 years, respectively. Preoperative WBL ratio and cartilage lesions in the medial compartment did not differ between the groups. Preoperative MME were significantly lower in group A than those in group B (2.6 ± 0.6 mm in group A and 3.5 ± 0.7 mm in group B, p < 0.05). Patient-reported outcomes at the 2-year follow-up did not differ between the two groups (n. s.). In a logistic analysis, the odds ratio of MME was 2.1 (p < 0.05), and the cutoff value of MME was 3.02 mm. Preoperative MME is a risk factor for varus progression. However, no differences in patient-reported outcomes were observed at 2-year follow-up, even in the group with greater varus progression. Level IV.

Accurate tibial tunnel position in transtibial pullout repair for medial meniscus posterior root tears delays the progression of medial joint space narrowing.

This study aimed to evaluate the association between the progression of medial joint space (MJS) narrowing, medial meniscus extrusion (MME) and clinical scores and the tibial tunnel position in pullout repairs for medial meniscus posterior root tears (MMPRTs). This retrospective study examined 54 patients. Changes in MJS (ΔMJS), MME (ΔMME) and clinical scores and their relationship with the tibial tunnel position were evaluated using correlation coefficients. The distance from the anatomical to technical attachment position in the tibial tunnel position was measured in the anterior and medial directions, and the direct distance was measured using the Pythagorean theorem. The mean ΔMJS and ΔMME were 0.6 ± 0.8 and 1.3 ± 1.3 mm, respectively, and the mean anterior, medial and direct distances were 1.4 ± 2.3, 2.2 ± 1.7 and 3.4 ± 1.7 mm, respectively. ΔMJS had a significant positive correlation with the medial (r = 0.580, p < 0.001) and direct (r = 0.559, p < 0.001) distances, while ΔMME had a significant positive correlation with direct distance (r = 0.295, p = 0.030). Several clinical scores were significantly negatively correlated with these distances. In transtibial pullout repair for MMPRTs, accurate tibial tunnel position delayed the progression of MJS narrowing and MME, leading to improved clinical outcomes. The progression of MJS narrowing was associated with the mediolateral direction of the tibial tunnel position, while the clinical scores were associated with the anteroposterior direction of the tibial tunnel position. These findings indicate the need to orient the tip of the guide in a more posterolateral direction when creating the tibial tunnel. Level IV.

Medial meniscus extrusion is associated with meniscus tears in US and MRI: A case control study.

To study the medial meniscus extrusion (MME) in subjects with and without medial meniscal tears on magnetic resonance imaging (MRI), supine ultrasound (US), and weight-bearing US. Forty-seven cases (mean age 43.7 years) with medial meniscus tears and 53 healthy controls (mean age 36.6 years) were assessed. Two experienced sonographers performed the US evaluations, and a fellowship-trained musculoskeletal radiologist assessed the menisci on MRI. Independent and paired T-tests and ICC were used for statistical analyses. On supine US, the mean MME was 3.9 mm for the cases and 2.3 mm for the controls (p < 0.001). On weight-bearing US, the values were 4.2 and 2.8 mm (p < 0.001), and on MRI 3.0 and 2.0 mm (p < 0.001), respectively. The mean difference between supine and weight-bearing US extrusion was 0.38 mm for the cases and 0.49 mm for the controls (p = 0.291). Correlation between supine US and MRI MME measurements was good (ICC = 0.660, CIs [0.533-0.758]). MME can be assessed using US with good correlation to MRI. US-observed extrusion was significantly increased in supine and standing positions for medial meniscus tears. The mean difference between examination positions was reduced with medial meniscus tears although this result was statistically insignificant.

Meniscal healing status after medial meniscus posterior root repair negatively correlates with a midterm increase in medial meniscus extrusion.

The second-look arthroscopic score of pullout repair for medial meniscus posterior root tears (MMPRTs) is associated with contemporaneous clinical scores and progression of cartilage damage. However, the relationship among these scores, midterm clinical scores and magnetic resonance imaging (MRI) evaluations is unknown. The relationship between the second-look arthroscopic score at 1 year and the clinical scores or MRI at 3 years was evaluated. Sixty-three patients were included. Medial meniscus extrusion (MME) was evaluated preoperatively and at 3 years postoperatively. Clinical scores were evaluated preoperatively, and 1 and 3 years postoperatively. Meniscal healing status was assessed using the semiquantitative second-look arthroscopic score at 1 year postoperatively. Correlation coefficients between patient characteristics, postoperative clinical scores or second-look arthroscopic score and the change in MME (ΔMME) were evaluated. Multiple regression analysis was performed on the ΔMME to evaluate the effects of patient characteristics and second-look arthroscopic scores. No significant correlation was observed between patient characteristics and ΔMME. In contrast, a significant correlation was found between the second-look arthroscopic score and ΔMME (p < 0.001) and visual analogue scale pain score (p = 0.016) at 3 years postoperatively. In the subitems of the second-look arthroscopic score, width (p < 0.001) and stability (p = 0.009) scores also showed significant correlations with ΔMME. Multiple regression analysis showed a significant association between the second-look arthroscopic score and ΔMME (p = 0.001). The second-look arthroscopic score at 1 year postoperatively correlated with the ΔMME and clinical score at 3 years postoperatively. Second-look arthroscopic scores predict midterm meniscal function after pullout repair of MMPRTs. Level IV.