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Purpose: 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)., Methods: 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., Results: 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., Conclusion: 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 of Evidence: Level IV., (© 2024 The Authors. Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Objectives: This study aimed to investigate whether the initial suture tension when pullout sutures are fixed affects postoperative clinical outcomes following medial meniscus posterior root repair., Methods: The data of 48 patients who underwent transtibial pullout repair using two simple stitches (outer and inner sutures) with an additional all-inside posteromedial pullout were retrospectively investigated. The patients were sequentially divided into two groups to compare the clinical efficacy of the initial pullout tension (N) when pullout sutures were fixed: the 30 N Group (April 2019 to September 2019, 24 patients) and the 15 N group (October 2019 to February 2020, 24 patients). The rate of suture breakage (suture cutout or rupture) at the second-look arthroscopy at 1 year postoperatively and clinical outcomes at 2 years postoperatively were compared between the two groups., Results: In both groups, each clinical score significantly improved at 2 years postoperatively. At the second-look arthroscopy, the rate of posteromedial suture breakage was significantly higher in the 30 N group (19 patients, 79 ​%) than in the 15 N group (10 patients, 42 ​%); the rate of outer suture breakage was also higher in the 30 N group (five patients, 21 ​%) than in the 15 N group (no patients). On comparing 2 years of preoperative clinical scores between the groups categorized according to posteromedial suture breakage, the pain score was significantly higher in the suture breakage group., Conclusions: The initial tension of pullout repair of the medial meniscus posterior root tear is related to suture breakages. To prevent suture breakage, 15 N is a more initially suitable condition than 30 N., Level of Evidence: Level III., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Only a few studies have assessed signal intensity after pullout repair for medial meniscus posterior root (MMPR) tears (MMPRTs) based on mid-term magnetic resonance imaging (MRI) evaluations. Therefore, this study aimed to assess the quantitative signal intensity of repaired posterior roots over time, up to 3 years postoperatively, and the related factors., Methods: This study included 36 patients who underwent pullout repair for MMPRTs and MRI examinations using the same MRI system. The signal intensity of the repaired posterior roots was quantitatively evaluated using the signal-to-noise quotient (SNQ). Medial meniscus extrusion (MME), the SNQ for MMPR, and clinical scores were assessed over 3 years postoperatively., Results: MME progressed over time until 3 years postoperatively, and its progression during this period was 1.61 ± 1.44 mm. The SNQ for MMPR decreased over time until 3 years postoperatively, and the change in the SNQ from 3 months to 3 years postoperatively (ΔSNQ) was 2.69 ± 1.69. All clinical scores significantly improved (p < 0.001). ΔSNQ was significantly correlated with body weight (correlation coefficient = -0.424, p = 0.010) and body mass index (correlation coefficient = -0.330, p = 0.050). However, ΔSNQ was not significantly correlated with preoperative or postoperative clinical scores., Conclusion: After pullout repair for MMPRTs, MME progressed to 3 years postoperatively. However, the signal intensity of the repaired posterior roots decreased, and clinical scores improved over time until 3 years postoperatively. Patient weight and body mass index were significantly correlated with the reduced signal intensity of the repaired posterior roots, suggesting that weight assessment in patients with MMPRTs is crucial., Level of Evidence: IV., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: We aimed to evaluate the longitudinal changes in medial meniscus extrusion (MME) and clinical scores at multiple time points up to 3 years after pullout repair for medial meniscus posterior root tears (MMPRTs)., Methods: This retrospective case series study included 64 patients who underwent pullout repair for MMPRTs and four MRI evaluations (preoperatively and at 3 months, 1 year, and 3 years postoperatively). MME was measured during the same time points. Clinical scores were assessed four times: preoperatively and at 1, 2, and 3 years postoperatively. Additionally, a multivariate analysis was performed on the change in MME (ΔMME) from the preoperative measurement point to 3 years postoperatively., Results: The ΔMME per month from the preoperative measurement point to 3 months postoperatively, from 3 months to 1 year postoperatively, and from 1 to 3 years postoperatively were 0.30, 0.05, and 0.01 mm/month, respectively. All clinical scores significantly improved 3 years postoperatively (p < 0.001). In a multiple regression analysis for ΔMME from the preoperative measurement point to 3 years postoperatively, sex significantly affected the outcome (p = 0.039)., Conclusion: Following pullout repair for MMPRTs with well-aligned lower extremities, although MME progression could not be entirely prevented, the rate of progression decreased over time, and clinical scores improved. In particular, MME progressed markedly during the first 3 months postoperatively. Additionally, sex had a significant influence on MME progression, suggesting that males may be able to expand the indications of pullout repair for MMPRTs., (© 2024. The Author(s).)

Background: Despite good clinical results, repair of medial meniscus (MM) posterior root tears (MMPRTs) may not completely prevent knee osteoarthritis progression. This study evaluated changes in the medial joint space (MJS) during the first and second years after repair, compared to narrowing in the contralateral knee, using fixed-flexion view (FFV) radiographs., Methods: Fifty-four patients who underwent pull-out repair for a unilateral MMPRT were included. FFV radiographs were obtained pre-operatively and at the 1- and 2-year post-repair timepoints to evaluate changes in the MJS and Kellgren-Lawrence grade bilaterally. Clinical outcomes were also evaluated., Results: The change in the MJS was greater in MMPRT knees than in contralateral knees during the first year (0.48 ± 0.80 mm vs. 0.09 ± 0.49 mm, p < 0.001), but this difference lessened in the second year (0.09 ± 0.36 mm vs. 0.07 ± 0.38 mm, p = 0.285). Kellgren-Lawrence grade progression in MMPRT knees was less in the second year. Clinical outcomes significantly improved at both 1 and 2 years post-repair than the pre-operative values (p < 0.001), with continued improvement in clinical outcomes in the second year. There was no significant correlation between patient characteristics and the change in the MJS from preoperatively to 2 years postoperatively., Conclusion: Pull-out repair for MMPRTs did not completely prevent MJS narrowing, but the rate of narrowing decreased in the second year (mean, 0.09 mm) compared to that in the first year (mean, 0.48 mm). MJS narrowing in the second year after MM posterior root repair was comparable to that of the contralateral knee. Clinical outcomes further improved over the second year after repair., Level of Evidence: IV., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The use of various strategies for arthroscopic meniscal repairs to save the meniscus and prevent the progression of knee osteoarthritis has gradually increased. We investigated the frequency of various arthroscopic treatments and the short-term clinical outcomes of symptomatic isolated medial meniscus (MM) injuries. This retrospective observational study included 193 patients (197 knees) who underwent arthroscopic meniscal treatment for isolated MM injuries between January 2016 and April 2019. Arthroscopic meniscal repairs were divided into two groups: transtibial pullout repairs of MM posterior root tears (MMPRTs) and arthroscopic meniscal repairs for other types of MM injuries. MMPRT pullout repair, other meniscal repairs, and partial meniscectomy were performed in 71.0%, 16.8%, and 12.2% of the knees, respectively. The ratio of women to men and the patient age were higher in the pullout-repair group than the meniscal-repair group. The Preoperative Knee Injury and Osteoarthritis Outcome Score subscale (as an index of daily living activities) was significantly lower in the pullout-repair group than the meniscus-repair group. However, no significant differences were observed in these scores among the two groups postoperatively. Our results suggest that familiarity with the diagnosis and treatment of MMPRTs is necessary for orthopedic surgeons to manage isolated MM injuries., Competing Interests: No potential conflict of interest relevant to this article was reported.

Purpose: This study investigated the impact of weight change on the success of transtibial pullout repair for medial meniscus (MM) posterior root tears (MMPRTs)., Methods: The study included 129 patients diagnosed with MMPRTs who had undergone transtibial pullout repair. The patients were screened between July 2018 and November 2021. Patient-reported outcomes were assessed preoperatively and at 12 months postoperatively using the Knee injury and Osteoarthritis Outcome Score (KOOS). MM extrusion (MME) and ΔMME (postoperative MME - preoperative MME) were calculated preoperatively and at 12 months postoperatively using magnetic resonance imaging., Results: Patients were divided into weight loss (body mass index [BMI] decrease of at least 0.5 kg/m 2 after primary repair; n = 63) and weight gain (BMI increase of at least 0.5 kg/m 2 ; n = 66) groups. Both groups had similar demographic variables and preoperative clinical scores; patient-reported outcomes significantly improved postoperatively. The weight loss group had significantly greater improvement in KOOS-quality of life (weight loss, 29.4 ± 23.7; weight gain, 23.9 ± 27.6; p = 0.034), lower postoperative MME (weight loss, 3.9 ± 1.7 mm; weight gain, 4.2 ± 1.2 mm; p = 0.043) and lower ΔMME (weight loss, 0.8 ± 0.8 mm; weight gain, 1.2 ± 0.9 mm; p = 0.002) than the weight gain group. Total arthroscopic healing scores (weight loss, 7.6 ± 1.0; weight gain, 7.2 ± 1.5; p = 0.048) and associated subscales, including anteroposterior bridging tissue width (weight loss, 4.0 ± 0.0; weight gain, 3.8 ± 0.7; p = 0.004) and MM posterior root stability (weight loss, 2.6 ± 0.7; weight gain, 2.4 ± 0.7; p = 0.041), significantly differed between the groups., Conclusions: Weight loss was associated with better meniscal healing and less MME progression after MMPRT repair, highlighting the significance of weight management in individuals undergoing meniscal surgery. These findings provide valuable insights into the clinical significance of weight loss in the success of transtibial pullout repair for MMPRTs., Level of Evidence: Level III., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: This retrospective study aimed to investigate the relationship between intercondylar notch width (ICNW), osteophyte width (OW), and the healing of medial meniscus posterior root tears (MMPRTs) following arthroscopic pullout repair., Methods: The study included 155 patients diagnosed with MMPRTs who underwent transtibial pullout repair. Meniscal healing status was evaluated on second-look arthroscopy using a previously reported meniscus healing score. Patients were divided into two groups based on this score: the high healing score (group HH, healing score ≥ 8 points) and suboptimal healing score (group SO, healing score ≤ 6 points) groups. Computed tomography scans were performed on patients 1 week postsurgery. ICNW and OW widths were measured and relatively evaluated based on their ratio to the intercondylar distance (ICD), represented as the ICNW/ICD ratio (%) and OW/ICD ratio (%), respectively. Patient-reported outcomes were assessed preoperatively and on second-look arthroscopy using the Knee injury and Osteoarthritis Outcome Score (KOOS) and visual analogue scale (VAS)., Results: There were no significant demographic differences between the SO and HH group (n = 35 and 120 patients, respectively). Regarding radiographic measurements, significant differences were observed in the ICNW/ICD ratio (group SO, 24.2%; group HH, 25.2%; p = 0.024), OW (group SO, 2.6 mm; group HH, 2.0 mm; p < 0.001), and OW/ICD ratio (group SO, 3.5%; group HH, 2.7%; p < 0.001). Both groups had similar preoperative clinical scores, but postoperative clinical scores, including KOOS-activities of daily living (group SO, 83.4; group HH, 88.7; p = 0.035) and VAS (group SO, 19.1; group HH, 11.3; p = 0.005), were significantly better in group HH., Conclusion: The study suggests that ICNW and OW may play a crucial role in MMPRT healing following arthroscopic pullout repair, as evidenced by the worse clinical outcomes associated with a narrower ICNW and wider OW. These findings highlight the potential significance of ICNW and OW assessments when evaluating meniscal repair indications., Level of Evidence: Level III., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Background: Transtibial pullout repair yields beneficial clinical outcomes in patients with medial meniscus (MM) posterior root tear. However, the relationship between repaired meniscal root healing status and postoperative clinical outcomes remains unclear. We aimed to evaluate changes in articular cartilage damage and clinical scores after pullout repair using two simple stitches (TSS)., Methods: Thirty-three patients who underwent pullout repair using TSS were assessed. Healing status was assessed by a semi-quantitative second-look arthroscopic scoring system comprising three evaluation criteria (width of bridging tissues, stability of the repaired root, and synovial coverage), 1 year postoperatively. MM medial extrusion (MMME) and cartilage damage were assessed preoperatively and 1 year postoperatively. The medial compartment was divided into 8 zones (A-H) for comparison of preoperative and 1-year postoperative cartilage damage. Clinical outcomes were evaluated using the Knee Injury and Osteoarthritis Outcome score, Lysholm score, International Knee Documentation Committee scores, and visual analogue scale pain score., Results: Although cartilage damage did not aggravate significantly in most medial compartment areas, MMME progressed at 1 year postoperatively. No statistical differences were observed in cartilage damage between the central-to-medial area of the medial femoral condyle and the medial tibial plateau area at 1 year postoperatively. Regarding semi-quantitative healing scores, the stability score was significantly correlated with the International Cartilage Repair Society grade at 1 year postoperatively. All 1-year and 2-year clinical scores significantly improved compared with the preoperative scores., Conclusion: Regarding TSS repair, stability of repaired meniscal root negatively correlated with cartilage damage in the medial compartment loading area. All 1-year and 2-year clinical scores significantly improved than those of the preoperative scores. Achieving MM stability is crucial for suppressing cartilage degeneration., Level of Evidence: IV case series study., Competing Interests: Conflict of interest The authors report no conflicts of interest., (Copyright © 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Recently, transtibial pullout repair of the medial meniscus (MM) posterior root tear (PRT) has become widely accepted and provides satisfactory clinical outcomes. Widening after cyclic loading or ultimate failure load using different suture materials and configurations has been studied. However, no study has compared the clinical outcomes using different suture materials. This study aimed to evaluate the clinical outcomes after performing MMPRT pullout repair using different suture materials. We hypothesized that better clinical outcomes would be achieved using ultra-high molecular weight polyethylene (UHMWPE) tape compared with a normal polyester suture. Thirty-seven patients who underwent MM posterior root repair between November 2019 and May 2020 were retrospectively investigated. Pullout repair was performed using a hollow no. 0 polyester suture ( n  = 14) and UHMWPE tape ( n  = 23). Clinical outcomes were assessed preoperatively and at 1 year postoperatively, using the Lysholm knee score, Knee Injury and Osteoarthritis Outcome Score, and visual analogue scale (VAS) pain score. The meniscal healing status was assessed using an arthroscopic scoring system (range: 0-10). All clinical scores were improved significantly in both groups. However, significantly higher meniscal healing scores and decreased VAS pain scores were observed in the UHMWPE group (7.3 ± 0.9 and 7.7 ± 11.3, respectively) than in the polyester group (5.6 ± 2.1 and 18.4 ± 18.6, respectively; p  < 0.01). Suture cut-out and loss of the root continuity were observed in some cases (three cases [21.4%] in the polyester suture group and one case [4.3%] in the UHMWPE tape group). Both suture materials led to satisfactory clinical outcomes at 1 year postoperatively, whereas the UHMWPE tape was useful for obtaining good meniscal healing and decreasing the VAS pain score., Competing Interests: None declared., (Thieme. All rights reserved.)

Purpose: The aim of this study was to compare the clinical outcomes of different subtypes of type 2 medial meniscus posterior root tears following transtibial pullout repair., Methods: In total, 147 patients (mean age: 66.2 ± 8.3 years) who were diagnosed with type 2 medial meniscus posterior root tears and underwent transtibial pullout repair were included. Patients were divided into 2A (n = 31), 2B (n = 90), and 2C (n = 26) groups according to tear type. Clinical outcomes were assessed pre-operatively and at second-look arthroscopy using the Knee injury and Osteoarthritis Outcome Score. The meniscal healing status was evaluated at second-look arthroscopy. Medial meniscus extrusion was calculated using magnetic resonance imaging pre-operatively and at second-look arthroscopy., Results: No significant differences in pre-operative or post-operative clinical scores were observed between each subtype, although clinical scores improved post-operatively for each subtype. Significant differences were noted in the anteroposterior width of the bridging tissues at second-look arthroscopy (2A, 7.1 ± 1.2; 2B, 6.2 ± 1.7; and 2C, 6.2 ± 1.7 mm; p = 0.045); type 2A tears were the widest. There was a significant difference in post-operative medial meniscus extrusion (2A, 3.2 ± 0.9; 2B, 4.0 ± 1.2; and 2C, 4.0 ± 1.4 mm; p = 0.004) and its progression (2A, 0.7 ± 0.6; 2B, 1.2 ± 0.8; and 2C, 1.2 ± 0.8 mm; p = 0.008), and type 2A tears were the shortest., Conclusion: Although there was no significant difference in the post-operative clinical scores among different type 2 tears in the short term, type 2A tears showed better healing and medial meniscus extrusion progression prevention, thus indicating the usefulness of classifying tear type in estimating post-operative outcomes., Level of Evidence: III., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: Medial meniscus (MM) posterior root tears (PRTs) lead to abnormal kinematic changes in the knee and may induce pathological external rotation of the tibia during knee flexion. This study aimed to investigate changes in the length and inclination of the anterior cruciate ligament (ACL) after MM posterior root repair using magnetic resonance imaging (MRI)., Methods: This retrospective study included 44 patients who underwent MM posterior root repair between 2016 and 2019. Clinical outcomes were evaluated before and after surgery. MRI examinations were performed at 10°/90° of knee flexion preoperatively and 3 months postoperatively. The ACL length, proximal angle, and distal angle were determined using the sagittal view. MM extrusion and ACL inclination angle were determined using the coronal view., Results: Clinical outcomes significantly improved 1 year after surgery. The postoperative ACL length (29.7 ± 2.4 mm) and proximal angle (47.0 ± 7.4°) at 90° of knee flexion decreased relative to the preoperative values (31.5 ± 2.3 mm and 51.8 ± 8.7°, P < 0.01). The postoperative ACL inclination (64.9 ± 5.6°) at 10° of knee flexion decreased relative to the preoperative value (69.7 ± 5.6°, P < 0.01)., Conclusion: Pathologically-stretched linear ACL at 90° of knee flexion and a steep ACL inclination at 10° of knee flexion could be reduced after MM posterior root repair. This suggests that pullout repair could restore MM function as a secondary stabilizer, thereby preventing meniscal and cartilage degeneration., (© 2022. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Purpose: Medial meniscus posterior root tears (MMPRTs) occur most frequently in middle-aged and older adults. However, this serious condition can also occur in younger patients. The purpose of this study was to compare anterior cruciate ligament (ACL) degeneration and sagittal medial tibial slope in young adults with and without MMPRT., Methods: Eighteen healthy volunteers, 18 young patients (20-49 years of age), and 30 middle-aged and older patients (50-70 years of age) with MMPRT repair were included in the study. Sex, body mass index (BMI), femorotibial angle, ACL degeneration, and medial tibial slope angle were compared among the groups. ACL degeneration and medial tibial slope angle were assessed using magnetic resonance imaging., Results: In the healthy volunteer group, the young patient group, and the older patient group, the medial tibial slopes were 3.5° ± 1.4°, 6.1° ± 2.7°, and 7.2° ± 1.9°, respectively, and the ACL degeneration rates were 5.6%, 38.9%, and 43.3%, respectively. Young patients with MMPRT had significantly steeper medial tibial slopes and ACL degeneration compared to those of the healthy volunteers (P < 0.05). The parameters of young patients were similar to those of older patients with MMPRT. In the multivariate logistic regression analysis, BMI, medial tibial slope, and ACL degeneration were significantly associated with MMPRT in young patients., Conclusion: BMI, steep medial tibial slope, and ACL degeneration contribute to MMPRT development in younger patients., Level of Evidence: Level III., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: Different methods are available to assess the healing status of repaired root for medial meniscus posterior root tears (MMPRT) using second-look arthroscopy. However, few studies are comparing them or validating their usefulness. Therefore, it was hypothesized that the semi-quantitative arthroscopic score might correlate more with 1-year clinical outcomes in patients with MMPRT than the qualitative evaluation., Methods: Data of 61 patients who underwent MMPRT pullout repair and second-look arthroscopy were retrospectively evaluated. The semi-quantitative arthroscopic scoring system was divided into three evaluation criteria: scores from 0 to 10 points include the width of the bridging tissue, stability of the repaired root, and synovial coverage. The qualitative evaluation was classified into 4 status; complete healing, lax healing, scar tissue healing, and failed healing according to the stability and mobility of the repaired root. Multivariate linear regression analyses were used to identify predictors of 1-year postoperative clinical outcomes, including Knee Injury and Osteoarthritis Outcome, Lysholm, or International Knee Documentation Committee scores. Spearman's correlation analysis was used to analyze the correlation between second-look arthroscopic score/qualitative evaluation and 1-year postoperative clinical outcomes. In addition, the optimal cutoff point of semi-quantitative arthroscopic score was determined by receiver operating characteristic (ROC) curve. The Mann-Whitney U test was used to compare clinical outcomes between patients with semi-quantitative arthroscopic scores ≥8 and scores <8., Results: All clinical scores significantly improved at 1 year postoperatively. A good correlation was observed between the semi-quantitative score and clinical scores, but none between qualitative evaluation and clinical scores. The optimal cutoff point of semi-quantitative second-look arthroscopic score was 8 points. Significantly, better clinical outcomes were observed in patients with semi-quantitative scores ≥8 points., Conclusions: All 1-year postoperative clinical scores were significantly improved. The semi-quantitative arthroscopic scores correlate more with 1-year clinical outcomes in patients with MMPRT than the qualitative evaluation., Level of Evidence: IV case series study., (Copyright © 2021 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Purpose: This study aimed to evaluate changes in the cleft width, defined as the distance between the lateral edge of the medial tibial plateau and that of the medial meniscus (MM) posterior root, using open magnetic resonance imaging (MRI) in patients with MM posterior root tear (MMPRT)., Methods: This study included 25 patients (20 women and 5 men; mean age: 65.2 years) who were diagnosed with MMPRT and underwent pullout repair. Upon coronal imaging, the cleft width was evaluated at the 10° and 90° flexed knee positions. The difference in the cleft width (defined as the cleft width at 90° minus the cleft width at 10°) was also calculated. Upon sagittal imaging, the MM posterior extrusion (MMPE) at 90° was also evaluated. Separate univariate linear regression models were used to determine the association between the time from injury to MRI and radiographic measurements., Results: The mean cleft width at 10° and 90° was 4.9 ± 2.6 mm and 7.4 ± 3.7 mm, respectively; the mean difference in cleft width was 2.5 ± 1.5 mm, and the mean MMPE at 90° was 3.7 ± 1.3 mm. There was a significant difference in cleft width at 10° and 90° (p < 0.001). The time from injury to MRI was significantly associated with the cleft width at 10° (R = 0.42; p = 0.023), cleft width at 90° (R = 0.59; p = 0.002), the difference in the cleft width (R = 0.62; p = 0.008), and MMPE at 90° (R = 0.53; p = 0.008)., Conclusion: This study demonstrates that the cleft width is significantly larger during knee flexion than during knee extension. Increased cleft width during knee flexion ("graben" sign) may help diagnose MMPRT, especially in cases where the cleft sign is unclear during knee extension., Level of Evidence: III., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: Transtibial pullout repair of medial meniscus posterior root tears (MMPRTs) cannot prevent the progression of knee osteoarthritis. Conversions of knee arthroplasties are occasionally required following MMPRT repair. However, other knee-related surgical treatments following MMPRT repair are unclear. This study was aimed at investigating the midterm clinical outcomes and knee-related surgical events following MMPRT repair., Methods: Patients with MMPRT underwent pullout repair using FasT-Fix modified Mason-Allen (F-MMA) suturing with an all-inside meniscal repair device. Thirty-two patients with follow-up duration >2 years were enrolled. We assessed the clinical outcomes and postoperative surgical treatment of both knees., Results: F-MMA pullout repair improved all clinical evaluation scores in patients with MMPRT at a mean follow-up of 36.1 months. Postoperative arthroscopic debridement was required for one patient. An additional MMPRT repair was performed in one patient on second-look arthroscopy. None of the patients required ipsilateral knee arthroplasty. In the contralateral knees, one pullout repair of a newly developed MMPRT and two knee arthroplasties were performed., Conclusions: This study demonstrated that F-MMA pullout repair yielded satisfactory clinical outcomes. However, subsequent knee-related surgeries were observed in 6.3% of the pullout-repaired knees and 9.4% of the contralateral knees. Our results suggest that surgeons should be aware of the worsening and/or occurrence of contralateral knee joint disease, even when the postoperative clinical outcomes are satisfactory following MMPRT repair., Level of Evidence: IV., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Purpose: Transtibial pullout repairs using two simple stitches (TSS) and a combination of TSS with posteromedial pullout repair (TSS + PMP) using an all-inside meniscal repair device have been reported previously for the treatment of medial meniscus (MM) posterior root tears. This study aimed to investigate the postoperative clinical outcomes of these techniques including MM extrusion (MME)., Methods: Fifty-two patients who underwent transtibial pullout repair were investigated and divided into TSS (n = 27) and TSS + PMP (n = 25) groups. The clinical outcomes were assessed using the Lysholm knee score and Knee Injury and Osteoarthritis Outcome Score 1 year postoperatively and compared between two groups. MME was measured using magnetic resonance imaging at 1 year postoperatively and compared between two groups., Results: A significant improvement in each clinical score was observed in both groups, and no significant difference was seen in clinical outcomes. Moreover, no significant difference in postoperative MME was observed in both groups (TSS and TSS + PMP: 3.5 mm and 3.8 mm, respectively). Though no significant progression of MME was observed in TSS group, a significant progression of it was observed in TSS + PMP group postoperatively., Conclusions: This study demonstrated that both techniques improved clinical outcomes in the short-term postoperative period. However, MME was progressed significantly in TSS + PMP group 1 year postoperatively, which indicated that PMP might not be a useful additional procedure for reducing the postoperative MME., (© 2021. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Purpose/aim of the Study: Previous studies have noted distinctions between medial meniscus posterior root and horn cells. However, the characteristics of root remnant cells have not been explored in detail. The purpose of this study was to evaluate the gene expression levels, proliferation, and resistance to mechanical stress of remnant and horn cells., Materials and Methods: Medial meniscus tissue samples were obtained from patients who underwent total or uni-compartmental knee arthroplasty. Cellular morphology, sry-type HMG box 9, type II collagen, and chondromodulin-I gene expression levels were analyzed. Collagen synthesis was assessed by immunofluorescence staining. Proliferation analysis after 4 h-cyclic tensile strain was performed., Results: Horn cells displayed triangular morphology, whereas root remnant cells appeared fibroblast-like. sry-type HMG box 9 mRNA expression levels were similar in both cells, but type II collagen and chondromodulin-I mRNA expressions were observed only in horn cells. The ratio of type II collagen-positive cells in horn cells was about 10-fold higher than that in root remnant cells, whereas the ratio of sry-type HMG box 9-positive cells was similar. A significant increase in proliferation was observed in root remnant cells compared to that in horn cells. Further, under cyclic tensile strain, the survival rate was higher in root remnant cells than in horn cells., Conclusions: Medial meniscus root remnant cells showed higher proliferation and resistant properties to cyclic tensile strain than horn cells and showed no chondromodulin-I expression. Preserving the medial meniscus posterior root remnant during pullout repair surgery might maintain mechanical stress-resistant tissue and support healing.

Background: During transtibial pullout repair of medial meniscus (MM) posterior root tears (MMPRTs), accurate tibial tunnel creation within the anatomic MM posterior root attachment seems critical. This study aimed to evaluate the tibial tunnel position created by a newly-developed Precision guide during pullout repair of MMPRTs., Methods: In 40 patients who underwent transtibial pullout repairs, the tibial tunnel was created using the Unicorn Meniscal Root (UMR) (n = 20) or Precision guide (n = 20). Three-dimensional computed tomography images of the tibial surface were evaluated postoperatively, using Tsukada's measurement method. The expected anatomic center of the MM posterior root attachment was defined as the center of three tangential lines corresponding to anatomic bony landmarks. The expected anatomic center (AC) and the tibial tunnel center (TC) were evaluated using the percentage-based posterolateral location on the tibial surface. The difference in the mediolateral and anteroposterior percentage distance between the AC and TC was calculated, as was the absolute distance between the AC and TC., Results: The mean AC was located 77.4% posterior and 40.1% lateral. The mean TC was similar in the UMR and Precision guide groups. There was no significant difference in the mediolateral percentage distance (UMR 3.9% vs. Precision 3.6%, p = 0.405), but a significant difference was observed in the anteroposterior percentage distance (UMR 3.5% vs. Precision 2.6%, p = 0.031). The mean absolute distance between the AC and TC was 3.9 mm and 3.5 mm (UMR and Precision guide groups, respectively) (p = 0.364)., Conclusions: The new Precision guide can create tibial tunnel in an optimal and stable position during pullout repair of MMPRTs., Competing Interests: Declaration of competing interest None., (Copyright © 2021 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Bone marrow edema (BME) after meniscus injury and risk factors for subchondral insufficiency fracture of the knee (SIFK) have been reported. However, their association with medial meniscus posterior root tear (MMPRT) remains unknown. We investigated the association of BME volume (BME-V), posterior shinycorner lesion (PSCL), and SIFK with MMPRT to examine the correlations between BME-V and medial meniscus extrusion (MME), PSCL and duration from injury to the time of magnetic resonance imaging (duration), and SIFK and duration. Twenty-nine patients who underwent surgery for MMPRT were included (mean age, 59.2; range, 39-84). The presence of PSCL, femoral BME-V (cm3), and SIFK grade (1-4) were evaluated. Preoperative factors, such as MME (mm) and duration (weeks), were investigated using multivariate linear/ logistic regression analyses. Multivariate linear regression analysis revealed duration as a significant factor for high-grade SIFK (p<0.01). Multivariate logistic regression analysis revealed duration as a significant factor for the presence of PSCL (odds ratio=0.94, p<0.05). A long duration of MMPRT leads to severe MME and highgrade SIFK (3 and 4), often resulting in knee arthroplasty. Early diagnosis of MMPRT and pullout repair can prevent severe MME and high-grade SIFK., Competing Interests: No potential conflict of interest relevant to this article was reported.

Purpose: The purpose of this study was to evaluate the influence of tibial rotation on the postoperative healing status of the medial meniscus (MM) following pullout repair of the MM posterior root tear (MMPRT)., Methods: Ninety-one patients (68 women and 23 men; mean age 63.3 ± 8.8 years) who had undergone transtibial pullout repair of MMPRT were enrolled in the study. The tibial external rotation angle (ERA) in each patient was measured postoperatively using computed tomography in the extended knee position. The meniscal healing status following transtibial pullout repair was assessed by second-look arthroscopy (mean postoperative period 12 months) using a previously published scoring system (range 0-10). The association between the ERA and the meniscal healing score was investigated using univariate linear regression models. The ERA cut-off for improved meniscal healing score (≥ 7) was determined using receiver-operating characteristic analysis., Results: The ERA and the meniscal healing score were significantly associated, confirming that increased ERAs were correlated with worse meniscal healing status (R =  - 0.28; P < 0.001). The optimum ERA cut-off value was 0.5°, with a sensitivity of 68% and a specificity of 63%. The mean meniscal healing scores were 7.3 and 6.2 among patients with ERAs < 0.5° and those with ERAs ≥ 0.5°, respectively (P < 0.001)., Conclusion: This study demonstrated that the ERA was significantly correlated with the postoperative meniscal healing status. Postoperative tibial rotation could be one of the factors affecting postoperative outcomes of pullout repair of MMPRT. Controlling the tibial rotation may possibly improve meniscal healing., Level of Evidence: III., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: The medial meniscus (MM) translates posteriorly and extrudes severely from the medial tibial plateau (MTP) during knee flexion in the MM posterior root tear (PRT) knee. Transtibial pullout repair of the MMPRT has been performed to regulate MM extrusion. This study aimed to evaluate pullout suture translation during knee flexion before and after posterior anchoring during pullout repair. We hypothesized that suture translation after posterior anchoring would be significantly decreased relative to that before posterior anchoring., Methods: Thirty-five patients who underwent MM posterior root repair were prospectively investigated. Pullout repair was performed using two cinch sutures (outer and inner sutures) and posterior anchoring through the MM posterior horn and an additional bone tunnel on the MTP. The translation of the outer suture from 0° to 90° of knee flexion was measured and compared before and after posterior anchoring intraoperatively. The MM morphologic features were measured using preoperative magnetic resonance imaging, and the correlation between these values and outer suture translation was evaluated., Results: The average outer suture translation after posterior anchoring (1.6 ± 1.5 mm) was significantly decreased relative to that before posterior anchoring (2.5 ± 1.7 mm, P < 0.01). No significant correlations were observed between the MM morphological features and outer suture translation., Conclusions: The posterior anchoring method with an MM posterior root repair is useful in decreasing posterior translation of the pullout suture during knee flexion, which might have an advantage in preventing suture pullout from the repaired MM, leading to good clinical outcomes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Backgrounds: Medial meniscus (MM) posterior root tear (PRT) results in joint overloading and degenerative changes in the knee, and pullout repair is recommended to prevent subsequent osteoarthritis. Diagnosing MMPRT is sometimes difficult, especially in the case of an incomplete tear. A posterior shiny-corner lesion (PSCL) is reported to be useful for diagnosis, although the association between MMPRT and PSCL is unknown. This study aimed to investigate the properties of PSCL, such as the location, volume, and duration from injury to the time of MRI (duration). We hypothesized that PSCL is observed in the early phase after the MMPRT onset., Methods: T2-weighted fat-suppression magnetic resonance imaging (MRI) was obtained from 55 patients with MMPRT preoperatively. The prevalence of the PSCL; giraffe neck, cleft, and ghost signs; severe MM extrusion (> 3 mm); and the PSCL volume were evaluated. The PSCL lesion elliptical volume (mm 3 ) was calculated by measuring the anteroposterior, transverse, and craniocaudal dimensions., Results: PSCL was observed in 34 (62%) cases. The mean volume of the PSCL was 102.0 mm 3 . A significantly shorter duration was observed in the PSCL-positive group (5.6 weeks) than that in the PSCL-negative group (40.9 weeks, P < 0.01), although no significant correlation was observed between the PSCL volume and duration. The sensitivity for the MMPRT was 90.5% when the cut-off duration value was 3 weeks and 81.8% when the cut-off value was 8 weeks., Conclusions: MRI examination may detect PSCL if it is performed early following MMPRT onset. Detecting PSCL may be useful in diagnosing MMPRT with high sensitivity., (© 2021. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Background: Medial meniscus (MM) posterior root repairs lead to favorable clinical outcomes in patients with MM posterior root tears (MMPRTs). However, there are few comparative studies in evaluating the superiority among several pullout repair techniques such as modified Mason-Allen suture, simple stitch, and concomitant posteromedial pullout repair. We hypothesized that an additional pullout suture at the MM posteromedial part would have clinical advantages in transtibial pullout repairs of the MMPRTs. The aim of this study was to compare the clinical usefulness among several types of pullout repair techniques in patients with MMPRTs., Methods: Eighty-three patients who underwent arthroscopic pullout repairs of the MMPRTs were investigated. Patients were divided into three groups using different pullout repair techniques: a modified Mason-Allen suture using FasT-Fix all-inside meniscal repair device (F-MMA, n = 28), two simple stitches (TSS, n = 30), and TSS concomitant with posteromedial pullout repair using all-inside meniscal repair device (TSS-PM, n = 25). Postoperative clinical outcomes and semi-quantitative arthroscopic meniscal healing scores (0-10 points) were evaluated at second-look arthroscopies., Results: No significant differences among the three groups were observed in patient demographics and preoperative clinical scores, except for preoperative Lysholm scores. At second-look arthroscopies, there were no significant differences among the three techniques in postoperative clinical outcomes and meniscal healing scores., Conclusions: This study demonstrated that the TSS-PM pullout repair technique did not show better scores in postoperative clinical outcomes and meniscal healings compared with the F-MMA and TSS techniques. Our results suggest that the concomitant posteromedial pullout suture may have no clinical advantage in the conventional pullout repairs for the patients with MMPRTs., Competing Interests: Declaration of competing interest The authors have no conflict of interest., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Purpose: The volume of medial meniscus (MM) extrusion at 10° and 90° knee flexions using three-dimensional (3D) magnetic resonance imaging (MRI) and assessed relevant clinical outcomes at 1-year follow-up were evaluated., Methods: Twenty-four patients who underwent MM posterior root repair were retrospectively reviewed. At 10° and 90° knee flexions, the meniscal extrusion distance and volume were measured using 3D meniscus models constructed by SYNAPSE VINCENT®. The correlation between Knee Injury and Osteoarthritis Outcome Score, Lysholm, International Knee Documentation Committee scores, Tegner activity, and pain visual analog scales and changes in MM extrusion were assessed., Results: No significant differences in the MM medial extrusion were observed between 10° and 90° knee flexions postoperatively. MM posterior extrusion (MMPE) decreased significantly at 10° and 90° knee flexions postoperatively. At 90° knee flexion, the meniscus volume at the intra-tibial surface increased at 3 and 12 months postoperatively. The MM extrusion volume increased slightly at 10° knee flexion; however, the volume decreased significantly at 90° knee flexion postoperatively. The change in MMPE significantly correlated with clinical scores. All 12-month clinical scores were significantly improved compared to preoperative scores., Conclusions: The progression of meniscus posterior extrusion and reduction of its volume at 90° knee flexion can be suppressed by MM posterior root repair. Postoperative clinical scores correlated with reductions of the posterior extrusion. Regarding clinical relevance, the dynamic stability of the meniscus can be maintained by MM posterior root repair, which is an effective therapeutic method for improving its clinical status., Level of Evidence: Level IV., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: A medial meniscus posterior root tear results in the loss of meniscal circumferential hoop stress and causes a pathological posteromedial extrusion of the medial meniscus. Although creating a tibial tunnel in the anatomic place improves postoperative medial meniscus posterior extrusion, no studies have evaluated the relationship between tibial tunnel position and clinical outcomes. This study aimed to evaluate how tibial tunnel positioning of medial meniscus posterior root pullout repair affects meniscal healing status and clinical outcomes., Methods: Sixty-two patients with 64 medial meniscus posterior root tears (mean age 62.8 ± 7.9 years) who had undergone pullout repairs and second-look arthroscopies were included. All 62 patients were Lachman test negative. Three-dimensional computed tomography images of the tibial surface were evaluated using a rectangular measurement grid to assess the tibial tunnel centre and medial meniscus posterior root attachment centre. Spearman's rank correlation analysis was undertaken to determine displacement distance from the medial meniscus posterior root attachment centre to the tibial tunnel centre and a meniscal healing score, as well as clinical outcomes at 1 year post-repair., Results: Tibial tunnel centres were located more anteriorly and medially than the medial meniscus posterior root attachment centre (mean distance 5.0 ± 2.2 mm). The mean meniscal healing score was 6.7 ± 1.8 of 10 possible points. The 1-year postoperative clinical scores showed significant improvement compared with preoperative scores for all the items. There was a significant negative correlation in the absolute distance between the medial meniscus posterior root attachment centre and the tibial tunnel centre with the meniscal healing score (ρ =  - 0.39, p = 0.002). Furthermore, there were significant positive correlations between the distance between the medial meniscus posterior root attachment centre and the tibial tunnel centre in the mediolateral direction and patient-based clinical outcomes (ρ = 0.25-0.43, p < 0.05)., Conclusion: Accurate placement of a tibial tunnel, especially in the mediolateral direction, significantly improved meniscal healing and clinical outcomes at 1 year following medial meniscus posterior root repair. Surgeons should create a medial meniscus posterior root tibial tunnel at the anatomic attachment with particular attention to the mediolateral position., Level of Evidence: Level IV., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: Medial meniscus posterior root tear (MMPRT) causes medial meniscus extrusion (MME) and leads to subchondral insufficiency fracture of the knee (SIFK). However, the progression of SIFK after MMPRT pullout repair remains unknown. This study aimed to investigate the progression of SIFK and compare clinical outcomes in patients with SIFK to those without SIFK after MMPRT pullout repair. We hypothesized that the progression of SIFK would be prevented by MMPRT pullout repair, and clinical outcomes would improve in all patients., Methods: The SIFK grade (1-4) was evaluated using T2-fat suppression magnetic resonance imaging. Thirty-eight patients without SIFK (n = 22) and with low-grade SIFK (1 and 2; n = 16) who underwent MMPRT pullout repair were included. Preoperative factors, such as the duration from injury to the time of magnetic resonance imaging/surgery (weeks), femorotibial angle (degree), MME (mm), and clinical outcomes were evaluated, as well as the progression of SIFK., Results: SIFK was identified in only 9 patients (grade 1) postoperatively. Significantly improved clinical outcomes were observed in all patients. Preoperative femorotibial angle, MME, and duration from injury to the time of magnetic resonance imaging/surgery were 177.1 ± 1.5°, 3.2 ± 1.6 mm, and 6.4 ± 7.0/10.1 ± 7.5 weeks, respectively. No significant difference in preoperative factors and clinical outcomes was observed between patients with SIFK and those without SIFK., Conclusions: MMPRT pullout repair prevented the progression of low-grade SIFK and improved clinical outcomes in all patients, although bone contusions (grade 1 SIFK) were not completely healed within 1 year. MMPRT pullout repair could be a good treatment option for optimizing clinical outcomes in patients with low-grade SIFK., Competing Interests: Declaration of competing interest None., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Purpose : Medial meniscus (MM) posterior root (PR) tear leads to severe MM posterior extrusion (PE), resulting in rapid knee cartilage degeneration. MMPR repairs are recommended to reduce MMPE, especially during knee flexion. However, the difference in MMPE between different repair techniques remains unknown. This study aimed to investigate preoperative and postoperative MMPE following several pullout repair techniques. We hypothesized that a technique using two simple stitches (TSS) would be more useful than FasT-Fix-dependent modified Mason-Allen suture (F-MMA) to prevent the progression of MMPE in knee extension. Methods : This retrospective study included 35 patients who underwent MMPR repair. To compare MMPE, patients were divided into two groups according to the use of F-MMA while grasping the posterior capsule and TSS without grasping it. Open magnetic resonance imaging was performed at 10° and 90° knee flexion preoperatively, and at 3 and 12 months postoperatively, and the MMPE of both groups was evaluated. Results : A significant difference was observed between preoperative and 3-month postoperative MMPE at 90° knee flexion in both groups ( p < .01). A significant difference was observed in 3- and 12-month postoperative MMPE at 10° knee flexion between both groups ( p = .04/.02), whereas no significant difference in the preoperative MMPE at 10° knee flexion was observed between them ( p = .45). Conclusions : Both repairs were found to be useful to reduce MMPE in knee flexion. Further, F-MMA repair increased MMPE in knee extension, unlike TSS repair. These findings suggest that TSS might have more advantages for load distribution when standing or walking.

Purpose: To assess the effects of transtibial pullout repair for medial meniscus posterior root tears (MMPRTs) among patients with early osteoarthritis of the knee as measured by the meniscus healing score and to determine whether the meniscus healing score correlates with the International Cartilage Repair Society (ICRS) grade progression., Methods: Forty-seven patients with mild osteoarthritic knees (Kellgren-Lawrence grade ≤ 2 and varus alignment < 5°) who underwent transtibial pullout repair less than 3 months after MMPRT onset were assessed. The association between meniscus healing scores at 1 year postoperatively and cartilage damage of the medial compartment (medial femoral condyle [MFC] and medial tibial plateau [MTP]) were evaluated. The MFC was divided into six zones (A to F) and the MTP into two zones (G and H). The mean ICRS grade for each zone was compared between the primary surgery and second-look arthroscopy. The correlation between cartilage damage and meniscus healing status at the time of second-look arthroscopy in each zone was analysed., Results: The mean time interval from injury to surgery was 63 days, and all clinical scores showed significant improvement. There were no significant differences in the extent of cartilage damage in areas B, C, E, or F (n.s.) for MFC or in areas G and H (n.s.) for MTP. The meniscus healing score and cartilage damage were correlated in the loading areas (B, C, E, and H; - 0.53, - 0.45, - 0.33, and - 0.38, respectively; p < 0.05)., Conclusion: Transtibial pullout repair of MMPRTs among patients with mild osteoarthritic knees improved the clinical outcomes and showed a negative correlation between high meniscus healing scores and ICRS grades in the medial compartment loading area. This study suggests that early surgery should be undertaken for patients with mild osteoarthritic knee who develop MMPRTs., Level of Evidence: Level IV., (© 2020. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: Medial meniscus posterior root tears (MMPRTs) can cause severe medial extrusion of the medial meniscus (MMME) and the progression of knee degenerative changes, inducing a high signal intensity of the meniscus on magnetic resonance imaging (MRI). Although MMME and intrameniscal signal intensity (IMSI) reportedly decreased within 3 months after MMPRT repair, no previous studies have reported these changes after a 1-year follow-up. This study aimed to investigate the 1-year postoperative changes in MMME and IMSI on MRI after using different suture techniques., Methods: Overall, 33 patients with MMPRT were evaluated, 22 underwent FasT-Fix-dependent modified Mason-Allen suture (F-MMA) repair, and 11 underwent two simple stitches (TSS) repair. MRI examinations were performed preoperatively and 1 year postoperatively. MMME and IMSI were determined using MRI., Results: A significant decrease in postoperative MMME was observed in the TSS group (4.1 ± 1.0) relative to that in the F-MMA group (5.1 ± 1.4, P = 0.03). A significant decrease in postoperative IMSI (0.75 ± 0.14) was observed relative to preoperative IMSI in the TSS group (P < 0.01), whereas postoperative IMSI (0.94 ± 0.25) was similar to preoperative IMSI in the F-MMA group (P = 0.06). Furthermore, a significant decrease in postoperative IMSI was observed in the TSS group relative to that in the F-MMA group (P < 0.01)., Conclusions: The most important finding of this study is that TSS repair yielded a greater decrease in MMME and IMSI than F-MMA repair in patients with MMPRT. These results suggest that TSS repair is more useful for restoring loading stress to the posterior horn of the medial meniscus., (© 2020. Springer-Verlag France SAS, part of Springer Nature.)

The treatment of medial meniscus posterior root tears (MMPRTs) has evolved to include a variety of repair strategies. This study investigated the location of the articular cartilage degeneration during second-look arthroscopy after transtibial pullout repair with a modified Mason-Allen suture using FasT-Fix (F-MMA) in 22 patients with MMPRTs. Second-look arthroscopy was performed approximately 1 year postoperatively to eval-uate the healing status of the medial meniscus (MM). Articular cartilage degeneration was assessed using the International Cartilage Repair Society grade at primary surgery and again at second-look arthroscopy. Articular surfaces of the medial/lateral femoral condyles, the medial/lateral tibial plateaus, the patella and the trochlea were divided into several subcompartments (MF 1-9, LF 1-9, MT 1-5, LT 1-5, P 1-9, T 1-3). Clinical evaluations used the Japanese Knee Injury and Osteoarthritis Outcome, Lysholm, and International Knee Documentation Committee scores. Second-look arthroscopic findings showed complete healing of the MM posterior root in all patients. Significant differences between pullout repair and second-look arthroscopy were observed for MF 2 and 4, LF 7, and P 7. All clinical outcomes were improved. Our results indicate that this technique improves clinical outcomes postoperatively and may prevent the progression of cartilage degenera-tion on the loading surface of the medial knee compartment., Competing Interests: No potential conflict of interest relevant to this article was reported.

Background: Severe chondral lesions and varus knee alignment are associated with poor outcomes following transtibial pullout repair for medial meniscus posterior root tears and meniscus tear is strongly associated with body mass index. The prognostic factors in well-aligned knees (femorotibial angle < 180°) with mild chondral lesions are unknown. Therefore, we investigated the prognostic factors in these patients. We hypothesized that high body mass index would lead to poor clinical outcomes following pullout repair of medial meniscus posterior root tears., Methods: We retrospectively reviewed the files of 28 patients who had undergone pullout repair of medial meniscus posterior root tears between October 2016 and December 2017. We recorded the baseline characteristics (age, gender, height, weight, and body mass index) and the time between injury and surgery. We recorded the International Knee Documentation Committee scores, Knee injury and Osteoarthritis Outcome Scores, and pain visual analog scale scores. Using magnetic resonance imaging preoperatively and 1 year after surgery, we measured the medial meniscus body width and absolute and relative medial meniscus extrusion. Pearson correlation and multivariate linear regression analyses were used to assess potential associations between these factors and clinical outcomes., Results: Age positively correlated (coefficient = 0.49, P < 0.01) and body mass index negatively correlated with the postoperative International Knee Documentation Committee score (coefficient = -0.64, P < 0.01). In multivariate linear regression analysis, body mass index was a significant factor leading to poor postoperative International Knee Documentation Committee score (R 2  = 0.29, P < 0.05)., Conclusions: Body mass index > 30 kg/m 2 is a risk factor for unfavorable clinical outcomes following pullout repair of medial meniscus posterior root tears in well-aligned knees., Level of Evidence: III, Comparative retrospective study., Competing Interests: Declaration of competing interest None., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Purpose: The purpose of this study was to evaluate the influence of tibial tunnel position in pullout repair for a medial meniscus (MM) posterior root tear (MMPRT) on postoperative MM extrusion., Methods: Thirty patients (median age 63 years, range 35-72 years) who underwent transtibial pullout repairs for MMPRTs were included. Three-dimensional computed tomography images of the tibial surface were evaluated using a rectangular measurement grid for assessment of tibial tunnel position and MM posterior root attachment. Preoperative and postoperative MM medial extrusion (MMME) and posterior extrusion (MMPE) at 10° and 90° knee flexion were measured using open magnetic resonance imaging., Results: Tibial tunnel centers were located more anteriorly and more medially than the anatomic center (median distance 5.8 mm, range 0-9.3 mm). The postoperative MMPE at 90° knee flexion was significantly reduced after pullout repair, although there was no significant reduction in MMME or MMPE at 10° knee flexion after surgery. In the correlation analysis of the displacement between the anatomic center to the tibial tunnel center and improvements in MMME, and MMPE at 10° and 90° knee flexion, there was a significant positive correlation between percentage distance and improvement of MMPE at 90° knee flexion., Conclusion: This study demonstrated that the nearer the tibial tunnel position to the anatomic attachment of the MM posterior root, the more effective the reduction in MMPE at 90° knee flexion. Our results emphasize that an anatomic tibial tunnel should be created in the MM posterior root to improve the postoperative MMPE and protect the articular cartilage in a knee flexion position. Placement of an anatomic tibial tunnel significantly improves the MMPE at 90° of knee flexion after MM posterior root pullout repair., Level of Evidence: IV.

Purpose: Contralateral medial meniscus posterior root tear (MMPRT) can sometimes occur after primary surgeries for MMPRT and lead to unsatisfactory outcomes. The incidence rate and risk factors for contralateral MMPRT have not been well investigated, despite their clinical importance. Therefore, the incidence and predictors of bilateral MMPRT were aimed to be evaluated., Methods: Fourteen patients with bilateral MMPRT (group B) and 169 patients with unilateral MMPRT (group U) were enrolled in this study. Sex, age, body mass index, time between injury and surgery, and medial tibial slope angle (MTSA) were compared between the groups. MTSA was measured using lateral radiographs., Results: The incidence rate of bilateral MMPRT was 6.2% among all patients with MMPRTs. Multivariate logistic regression analysis showed that a prolonged time between injury and surgery (odds ratio [OR], 1.0; 95% confidence interval [CI] 1.00-1.01; P < 0.05) and steeper MTSA (OR, 1.85; 95% CI 1.21-2.64; P < 0.01) were significantly associated with the development of bilateral MMPRT. Receiver operating characteristic curve analysis showed that MTSA > 10.0° was associated with bilateral MMPRT, with a sensitivity of 93% and specificity of 69%., Conclusion: A longer time between injury and surgery and steeper MTSA were risk factors for the development of bilateral MMPRT. Surgeons need to pay close attention to the contralateral knee in addition to the primary injured knees when treating knees with steep MTSA. Besides, early meniscal repair of primary MMPRT would be important to prevent the events of contralateral MMPRT., Level of Evidence: III.

Background: Many histological, mechanical, and clinical studies have been performed on the medial meniscus posterior root attachment, as it often tears in patients with osteoarthritic knee. Medial meniscal root repair is recommended in clinical situations; however, to date, no studies have examined the differences between meniscal root and horn cells. The aim of this study was, therefore, to investigate the morphology, reaction to cyclic tensile strain, and gene expression levels of medial meniscal root and horn cells., Methods: Meniscal samples were obtained from the medial knee compartments of 10 patients with osteoarthritis who underwent total knee arthroplasty. Root and horn cells were cultured in Dulbecco's modified Eagle's medium without enzymes. The morphology, distribution, and proliferation of medial meniscal root and horn cells, as well as the gene and protein expression levels of Sry-type HMG box 9 and type II collagen, were determined after cyclic tensile strain treatment., Results: Horn cells had a triangular morphology, whereas root cells were fibroblast-like. The number of horn cells positive for Sry-type HMG box 9 and type II collagen was considerably higher than that of root cells. Although root and horn cells showed similar levels of proliferation after 48, 72, or 96 h of culture, more horn cells than root cells were lost following a 2-h treatment with 5% and 10% cyclic tensile. Sry-type HMG box 9 and α1(II) collagen mRNA expression levels were significantly enhanced in both cells after 2- and 4-h cyclic tensile strain (5%) treatment., Conclusions: Medial meniscal root and horn cells have distinct morphologies, reactions to mechanical stress, and cellular phenotypes. Our results suggest that physiological tensile strain is important to activate extracellular matrix production in horn cells., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Medial meniscus (MM) posterior root repairs show favorable clinical outcomes in patients with MM posterior root tears (MMPRTs). However, there is no useful magnetic resonance imaging (MRI) finding to determine a functionally good meniscal healing following MM posterior root repairs. We hypothesized that a characteristic postoperative MRI finding can predict a good meniscal healing following pullout repairs. The aim of this study was to investigate a clinical usefulness of several MRI findings for estimating an actual meniscal healing following MMPRT repairs., Methods: Fifty eight patients who had a posteromedial painful popping of the injured knee and underwent an arthroscopic pullout repair for the MMPRT were included. Arthroscopic meniscal healing was assessed according to the Furumatsu scoring system at 1 year postoperatively. We evaluated postoperative MRI-based meniscal healing using signal intensity, continuity, suspension bridge-like sign of the MM posterior root, and MM medial extrusion on coronal images. Postoperative clinical outcome evaluations were performed at second-look arthroscopy., Results: Twenty three patients showed good arthroscopic healing scores (≥7 points). Thirty five patients had moderate/poor arthroscopic healing scores (<7 points). At 1-year follow-up period, clinical outcome scores were significantly higher in the good healing group than in the moderate/poor healing group. A characteristic meniscal shape, termed "suspension bridge sign", was highly observed in the good meniscal healing group (83%) compared with in the moderate/poor healing group (26%, P < 0.001). High signal intensity and continuity of the MM posterior root and MM medial extrusion showed no differences between both groups., Conclusions: Our study demonstrated that the MRI-based suspension bridge sign can predict an arthroscopically favorable meniscal healing following the MM posterior root repair. The suspension bridge-like MRI finding of the MM would be a useful indicator to evaluate the actual meniscal healing in patients who underwent pullout repairs for MMPRTs., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Purpose: Bone morphological factors are important for menisci. Their association with medial meniscus posterior root tears, however, has not yet been studied. This study aimed to compare sagittal medial tibial slope and medial tibial plateau depth between knees with and without medial meniscus posterior root tears., Methods: Nine healthy volunteers, 24 patients who underwent anterior cruciate ligament reconstruction, and 36 patients who underwent medial meniscus posterior root pullout repair were included. Magnetic resonance imaging examinations were performed in the 10°-knee-flexed position. The medial tibial slope and medial tibial plateau depth were compared among the groups., Results: In healthy volunteers, the anterior cruciate ligament reconstruction group, and the medial meniscus posterior root tear group, the medial tibial slopes were 3.5° ± 1.4°, 4.0° ± 1.9°, and 7.2° ± 1.9°, respectively, and the medial tibial plateau depths were 2.1 ± 0.7 mm, 2.2 ± 0.6 mm, and 1.2 ± 0.5 mm, respectively. Patients with medial meniscus posterior root tears had a significantly steep medial tibial slope and shallow medial tibial plateau concavity compared to those of healthy volunteers (P < 0.01) and the anterior cruciate ligament group (P < 0.01). In the multivariate logistic regression analysis, body mass index, medial tibial slope, and medial tibial plateau depth were significantly associated with medial meniscus posterior root tears., Conclusions: A steep posterior slope and a shallow concave shape of the medial tibial plateau are risk factors for medial meniscus posterior root tear., Level of Evidence: Level III: Case-control study.

Background: Medial meniscus (MM) translates and extrudes posteriorly during knee flexion in MM posterior root tear (MMPRT) knees, and transtibial pullout repair of MMPRT has been performed to regulate the MM extrusion. This study aimed to calculate each suture translation during knee flexion in transtibial pullout repair of MMPRT, and to investigate the morphologic features of the MM that lead to longer suture translations during knee flexion., Methods: Thirty patients with MMPRT who met the operative indication of pullout repair were enrolled and investigated prospectively. Pullout repair was performed by using two simple stitches (outer and inner sutures) and an all-inside suture in the posteromedial part of the MM. Each suture's translation from 0° to 90° of knee flexion was measured intraoperatively. The MM morphologic features, including MM medial extrusion (MMME) and MM posterior height (MMPH), were measured using preoperative magnetic resonance imaging, and the correlation between these values and each suture translation was evaluated., Results: The average outer, inner, and all-inside suture translations were 4.8 mm, 3.9 mm, and 1.3 mm, respectively. Significant correlations were observed between the outer suture translation and MMME, and MMPH (p < 0.001 and <0.01, respectively). The thresholds for preoperative MMME and MMPH for longer outer suture translations (≥6 mm) were 2.1 mm and 5.4 mm, respectively., Conclusions: Preoperative longer MMME and higher MMPH were associated with longer meniscus translations during knee flexion during MMPRT repair., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Purpose: To investigate changes in meniscal extrusion during knee flexion before and after pullout fixation for medial meniscus posterior root tear (MMPRT) and determine whether these changes correlate with articular cartilage degeneration and short-term clinical outcomes., Methods: Twenty-two patients (mean age 58.4 ± 8.2 years) diagnosed with type II MMPRT underwent open magnetic resonance imaging preoperatively, 3 months after transtibial fixation and at 12 months after surgery, when second-look arthroscopy was also performed. The medial meniscus medial extrusion (MMME) and the medial meniscus posterior extrusion (MMPE) were measured at knee 10° and 90° flexion at which medial meniscus (MM) posterior translation was also calculated. Articular cartilage degeneration was assessed using International Cartilage Research Society grade at primary surgery and second-look arthroscopy. Clinical evaluations included Knee Injury and Osteoarthritis Outcome Score, International Knee Documentation Committee subjective knee evaluation form, Lysholm score, Tegner activity level scale, and pain visual analogue scale., Results: MMPE at 10° knee flexion was higher 12 months postoperatively than preoperatively (4.8 ± 1.5 vs. 3.5 ± 1.2, p = 0.01). MMPE at 90° knee flexion and MM posterior translation were smaller 12 months postoperatively than preoperatively (3.5 ± 1.1 vs. 4.6 ± 1.3, 7.2 ± 1.7 vs. 8.9 ± 2.0, p < 0.01). Articular cartilage degeneration of medial femoral condyle correlated with MMME in knee extension (r = 0.5, p = 0.04). All clinical scores significantly improved 12 months postoperatively. However, correlations of all clinical scores against decreased MMPE and increased MMME were not detected., Conclusions: MMPRT transtibial fixation suppressed the progression of MMPE and cartilage degeneration and progressed MMME minimally in knee flexion position at 1 year. However, in the knee extension position, MMME progressed and correlated with cartilage degeneration of medial femoral condyle. MMPRT transtibial fixation contributes to the dynamic stability of the MM in the knee flexion position., Level of Evidence: IV.

Objectives: To identify the diagnostic performance of magnetic resonance imaging (MRI) in the knee-flexed position for the detection of meniscal ramp lesions in patients with anterior cruciate ligament tears., Materials and Methods: Forty-three patients (mean age 24.5 ± 9.5 years; 21 males, 22 females) with an arthroscopically proven anterior cruciate ligament tear were included in this retrospective study. The presence of the following two important features on MRI was recorded: irregularity of the medial meniscus at the posterior margin, and complete fluid filling between the posterior horn of the medial meniscus and the capsule margin. Findings obtained in arthroscopy served as the reference standard. The diagnostic sensitivity, specificity, and inter-observer agreement were calculated., Results: Sixteen ramp lesions were noted on arthroscopy (37.2%). With an irregularity of the medial meniscus at the posterior margin on MRI, the sensitivity and specificity were 87.5 and 59.3% at 10° knee flexion and 93.8 and 85.2% at 90° flexion, respectively. The complete fluid filling sign on MRI showed sensitivity and specificity of 31.3 and 100% at 10° knee flexion and 87.5 and 100% at 90° flexion, respectively. The concordance between the two observers for the two MRI features was very good (k = 0.70-0.88)., Conclusion: MRI with the knee in the flexed position improves the diagnostic performance of the detection of meniscal ramp lesions compared with MRI with the knee in the extended position.

Purpose: Transtibial repair of a medial meniscus posterior root tear (MMPRT) can improve clinical outcomes, although meniscal extrusion remains. However, few studies have investigated the volume of meniscal extrusion. This study aimed to evaluate the effect of transtibial repair in reducing the volume using three-dimensional (3D) magnetic resonance imaging, at 10° and 90° knee flexion., Methods: Twenty patients with MMPRTs and 16 volunteers with normal knees participated. The 3D models of meniscus were constructed using SYNAPSE VINCENT ® . The meniscal extrusion and its volume were measured at 10° and 90° knee flexion. Differences between the pre- and postoperative examinations were assessed using the Wilcoxon signed-rank test. The postoperative parameters were compared to those in patients with normal knees., Results: There were no significant pre- and postoperative differences in any parameter at 10° knee flexion. At 90° knee flexion, the posterior extrusion and its meniscal volume were decreased significantly after transtibial repair (p < 0.05), even though these parameters were larger than in the normal knees. On the other hand, intra-articular meniscal volume calculated by the extrusion volume was increased to the level of the normal knee., Conclusions: This study demonstrated that transtibial repairs improved the intra-articular/intra-tibial surface volume of the medial meniscus by reducing the posteromedial extrusion during knee flexion. This 3D analysis is clinically relevant in evaluating that, while transtibial root repair has a limited ability to reduce meniscal extrusion, it can restore the functional volume of the medial meniscus which contributes to the shock absorber postoperatively., Level of Evidence: IV.

Purpose: This study aimed to clarify the advantages of three-dimensional (3D) magnetic resonance imaging (MRI) over two-dimensional (2D) MRI in measuring the size of the medial meniscus (MM) and to analyse the volumes of MM and the extruded meniscus in patients with MM posterior root tear (MMPRT), at 10° and 90° knee flexion., Methods: This study included 17 patients with MMPRTs and 15 volunteers with uninjured knees. The MMs were manually segmented for 3D reconstruction; thereafter, the extruded part separated from the tibial edge was determined. The length, width, height, and extrusion of MM were measured by the 2D and 3D methods, and compared. The MM volume, extruded meniscus volume, and their ratio were also calculated using 3D analysis software in the two groups., Results: The estimated length and posterior height of MM were larger with 3D MRI than with 2D MRI measurements. The MM volume was significantly greater in MMPRT knees than in normal knees, with increasing MM height. In MMPRT knees, the mean volume of the extruded meniscus and its ratio significantly increased by 304 mm 3 (p = 0.02) and 9.1% (p < 0.01), respectively, during knee flexion., Conclusions: This study demonstrated that 3D MRI could estimate the precise MM size and that MMPRT caused swelling of the meniscus due to the increased thickness in the posteromedial part. The clinical significance of this study lies in its 3D evaluation of MM volume, which should help the surgeon understand the biomechanical failure of MM function and improve MMPRT repair technique., Level of Evidence: III.

Background: Two types of repair techniques, FasT-Fix modified Mason-Allen (F-MMA) and two simple stitches (TSS), for the treatment of a medial meniscus posterior root tear (MMPRT) were previously reported. However, whether these techniques could prevent postoperative medial meniscus extrusion (MME) progression is unknown. This study investigated and compared postoperative MME of the two repair techniques., Methods: Forty-seven knees that had undergone pullout repair for MMPRT were retrospectively reviewed. These knees were divided into two groups as follows: In 26 knees, MMPRT was treated using the F-MMA technique and fixed with the knee flexed at 45° and 20 N of tension [F-MMA (45°-20 N) group], and in 21 knees, MMPRT was treated using the TSS technique and fixed with the knee flexed at 20° and 30 N of tension [TSS (20°-30 N) group]. The medial meniscus body width (MMBW), absolute MME (aMME), and relative MME (rMME = absolute MME/MMBW) were measured and compared using magnetic resonance imaging 3 months postoperatively. The Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales for clinical outcomes were compared between the two groups at 6 months postoperatively., Results: At 3 months postoperatively, the aMME and rMME significantly decreased in the TSS (20°-30 N) compared to the F-MMA (45°-20 N) group. The TSS (20°-30 N) group had better KOOS subscale scores than the F-MMA (45°-20 N) group at 6 months postoperatively., Conclusions: The TSS technique with appropriate tibial fixation can decrease MME soon after surgery. This may prevent osteoarthritis progression and improve clinical outcomes.

Background: Transtibial pullout repair of a medial meniscus posterior root tear (MMPRT) is a commonly used procedure, and several techniques have been reported. We hypothesised that pull-out repairs using two simple stitches (TSS) would have similar postoperative outcomes as those using the modified Mason-Allen suture with FasT-Fix (F-MMA). We aimed to investigate the clinical outcomes of these techniques, including the meniscal healing status and osteoarthritic change., Methods: The data of 68 patients who underwent transtibial pull-out repair were retrospectively investigated. The patients were divided into two groups of 41 and 27 patients using F-MMA and TSS, respectively. The clinical outcomes were assessed preoperatively and at second-look arthroscopy (the mean period from surgery was one year) using the Knee injury and Osteoarthritis Outcome Score. The meniscal healing status, evaluated at second-look arthroscopy, was compared between the two groups. The cartilage damage was graded as per the classification of the International Cartilage Repair Society and compared at the primary surgery and second-look arthroscopy., Results: Both groups showed significant improvement in each clinical score. No significant difference was seen in the clinical outcome scores and the meniscal healing status between the two groups at second-look arthroscopy. Moreover, no significant progression of cartilage damage was observed in both groups. Fourteen patients in the F-MMA group developed a complication of suture bar failures postoperatively; however, there were no complications in the TSS group., Conclusions: The TSS and F-MMA techniques showed favourable clinical outcomes and would be established as clinically useful techniques for the MMPRT treatment., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: To investigate the relationship between tibial tunnel aperture location and postoperative meniscal healing., Methods: We enrolled 25 patients (20 women and five men, mean age: 62.5 years) who underwent transtibial pullout repair for medial meniscus (MM) posterior root repair. The expected MM posterior root attachment center (AC) and tibial tunnel center (TC) were identified using three-dimensional computed tomography, and the minimum AC-TC distance was calculated. The meniscal healing status following transtibial pullout repair was assessed by second-look arthroscopy (mean postoperative period: 15 months) using a previously reported scoring system (meniscal healing score; range: 0-10). The association between AC-TC distance and meniscal healing score was investigated using univariate linear regression models. The optimal AC-TC distance cut-off for improved MM healing score (≥7) was determined using receiver operating characteristic analysis., Results: The AC-TC distance and meniscal healing score were significantly associated (y = -0.42x + 9.48, R 2  = 0.342; P = 0.002), with the optimum AC-TC distance being 5.8 mm. This cut-off had a sensitivity of 100% and specificity of 53%., Conclusions: This study demonstrates that AC-TC distance is significantly correlated with postoperative meniscal healing. Anatomical repair within 5.8 mm of the AC may result in improved meniscal healing., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Lateral meniscus (LM) posterior root tear (PRT) is often associated with anterior cruciate ligament (ACL) injury and can result in rotational instability, joint overloading, and degenerative changes in the knee. Improved rotational stability and kinematics have been reported after LMPRT repair. However, it is unclear what repair technique can achieve the greatest reduction in LM extrusion (LME)., Hypothesis: We hypothesized that transtibial pullout repair would decrease LME to a greater extent than other repair techniques., Patients and Methods: Seventeen patients with ACL injury and complete LMPRT were evaluated. Nine underwent ACL reconstruction (ACLR) and transtibial pullout repair, and eight underwent ACLR and other repairs such as inside-out suturing. Double-bundle ACLR was performed using hamstring tendons, and LMPRT pullout repair was performed through the bone tunnel for the posterolateral bundle. Magnetic resonance imaging was performed immediately preoperatively and at>6 months postoperatively, and LME was measured from coronal images only., Results: A significantly greater decrease in the value of LME from pre- to postoperative measurement was observed in the transtibial pullout repair group (-0.5±0.7mm) than in the other-repair group (1.0±0.9mm, p<0.01). Pre- and postoperative LME measurements were not significantly different between the two groups., Discussion: The most important finding of this study was that transtibial pullout repair resulted in a greater decrease in LME than other repair techniques in patients with ACL injury and LMPRT. This technique might be useful for restoring hoop tension by decreasing LME., Level of Evidence: III, comparative retrospective study., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Background: Medial meniscus (MM) medial extrusion in the coronal plane does not always improve, even after repair. This study aimed to determine the extent of posteromedial extrusion of the MM during knee flexion before and after MM pullout repair using three-dimensional magnetic resonance imaging (MRI)., Methods: Data from 14 patients (mean age, 63.4 years; 86% female) who had undergone MM pullout repair at the current institution between August 2017 and October 2018 were retrospectively reviewed. The MRIs were performed pre-operatively and ≥3 months postoperatively. Three-dimensional MRIs of the tibial surface and MM were evaluated using Tsukada's measurement method before and after pullout repair. The expected center of MM posterior root attachment (point A), the point on the extruded edge of the MM farthest away from point A (point E), and the point of intersection of a line through the posteromedial corner of the medial tibial plateau and a line connecting points A and E (point I) were identified. Subsequently, the pre-operative and postoperative AE and IE distances were calculated and compared., Results: Point E was laterally shifted by the pullout repair, whereas point I showed no significant change. The postoperative IE distance (6.7 mm) was significantly shorter than the pre-operative one (9.1 mm, P < 0.01). The postoperative AE distance (29.3 mm) was significantly shorter than the pre-operative one (31.5 mm, P < 0.01)., Conclusions: The AE and IE distances significantly decreased after MM posterior root repair, suggesting that transtibial pullout repair may be useful in reducing posteromedial extrusion of the MM., Competing Interests: Declaration of competing interest None., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Medial meniscus posterior root tear causes rapid knee cartilage degradation by inducing posteromedial displacement of the medial meniscus. We evaluated medial meniscus posterior extrusion before and after pullout repair for medial meniscus posterior root tear using magnetic resonance images. Twenty-eight patients with symptomatic medial meniscus posterior root tear were included. The inclusion criteria were: acute (< 3 months) or chronic (≥3 months) medial meniscus posterior root tear after painful popping events. The exclusion criteria were: other meniscus and anterior cruciate ligament injuries. We measured medial meniscus posterior extrusion and medial meniscus anteroposterior interval at knee flexion angles of 10° and 90° preoperatively and at 3 months postoperatively. The posterior extrusion at 90° knee flexion decreased from 4.42±1.38 mm preoperatively to 3.09±1.06 mm (p<0.001) postoperatively, while at 10° knee flexion it was -4.17±1.63 mm preoperatively and -3.77±1.72mm postoperatively, showing no significant change. The anteroposterior interval at 10° knee flexion increased from 19.74±4.27 mm preoperatively to 22.15±5.10 mm postoperatively (p<0.001); at 90° knee flexion, it increased from 16.81±4.51 mm preoperatively to 19.20±4.30 mm postoperatively (p<0.001). Medial meniscus posterior extrusion and movement decreased after pullout repair. Pullout repair for medial meniscus posterior root tear improves medial meniscus posterior extrusion, especially at 90° knee flexion., Competing Interests: No potential conflict of interest relevant to this article was reported.

The medial meniscus (MM) posterior root has important functions in preventing an excessive loading stress during knee motion and degeneration of the articular cartilage. Although the transtibial pullout repair has become the gold standard for MM posterior root tears (MMPRTs), MM extrusion remains. In addition, during knee extension to deep flexion, the MM posterior segment in the MMPRT knee has been shown to translate toward the posteromedial direction, causing a notable MM posterior extrusion. Thus, the reduction in the MM posteromedial extrusion is one of the important postoperative outcomes to restore the meniscal function and eventually prevent the progression of knee osteoarthritis. The present technical note describes an arthroscopic technique addition to the pullout repair, in which an all-inside suture is inserted into the posteromedial part of the MM to reduce the MM posteromedial extrusion.