Male sex, revision surgery, low volume of anterior cruciate ligament remnant, and significant instability are risk factors for Posterior Root Tear of the Lateral Meniscus in patients undergoing Anterior Cruciate Ligament Reconstruction.

PURPOSE: This multicenter study aimed to determine the incidence of lateral meniscus posterior root tears (LMPRTs) in patients undergoing ACL reconstruction and identify associated risk factors. METHODS: We conducted a retrospective, multicenter study using data from the Francophone Arthroscopic Society's registry. The study included all the patients in the registry who underwent ACL reconstruction surgery between June 2020 and June 2023, we excluded incomplete data. We compared delay from injury to surgery between LMPRTs group and No LMPRTs group. Variables investigated as potential risk factors for LMPRTs included age, sex, nature of surgery (primary or revision), pivot shift test result, side-to-side laxity under anesthesia, presence of ACL remnant, occurrence of medial meniscal tear, and presence of collateral ligament injury. Risk factors were analyzed using a logistic regression model. RESULTS: Among the 5359 patients analyzed, LMPRTs occurred in 7.0% (n=375) of cases during ACL reconstruction. Mean age at surgery was 29.3 +/- 10.3 years old [11-77]. Concerning delay to surgery, the mean time was 8.4 +/- 23.1 weeks [0.0-347.2] in the No LMPRTs group and 6.5 +/- 10.2 weeks [0.2-61.6] in the LMPRTs group (p = 0.109). Univariate analysis revealed that male sex (p < 0.001), revision surgery (p < 0.001), medial meniscal injury (p = 0.007), ACL remnant (0% vs > 70%, <10% vs > 70%, 10 to 30% vs > 70%, 30 to 50% vs > 70%, 50 to 70% vs > 70%; p < 0.001) and higher pivot shift grade (p = 0.011) were significantly associated with a presence of LMPRTs. Age, side-to-side laxity, and collateral ligament injury were not found to be significant risk factor In multivariate analysis : male sex, revision surgery, pivot shift test result and a low volume of ACL remnant remained significant. Side to side laxity was also a significant factor in multivariate analysis. CONCLUSION: This study identified male sex, revision surgery, low volume of ACL remnant, side to side laxity and higher grade of pivot shift as significant risk factors for LMPRTs during ACL reconstruction.

Seven tesla knee MRI T2*-mapping detects intrasubstance meniscus degeneration in patients with posterior root tears.

Background: Medial meniscus root tears often lead to knee osteoarthritis. The extent of meniscal tissue changes beyond the localized root tear is unknown. Purpose: To evaluate if 7 Tesla 3D T2*-mapping can detect intrasubstance meniscal degeneration in patients with arthroscopically verified medial meniscus posterior root tears (MMPRTs), and assess if tissue changes extend beyond the immediate site of the posterior root tear detected on surface examination by arthroscopy. Methods: In this prospective study we acquired 7 T knee MRIs from patients with MMPRTs and asymptomatic controls. Using a linear mixed model, we compared T2* values between patients and controls, and across different meniscal regions. Patients underwent arthroscopic assessment before MMPRT repair. Changes in pain levels before and after repair were calculated using Knee Injury & Osteoarthritis Outcome Score (KOOS). Pain changes and meniscal extrusion were correlated with T2* using Pearson correlation (r). Results: Twenty patients (mean age 53 ± 8; 16 females) demonstrated significantly higher T2* values across the medial meniscus (anterior horn, posterior body and posterior horn: all P < .001; anterior body: P = .007), and lateral meniscus anterior (P = .024) and posterior (P < .001) horns when compared to the corresponding regions in ten matched controls (mean age 53 ± 12; 8 females). Elevated T2* values were inversely correlated with the change in pain levels before and after repair. All patients had medial meniscal extrusion of ≥2 mm. Arthroscopy did not reveal surface abnormalities in 70% of patients (14 out of 20). Conclusions: Elevated T2* values across both medial and lateral menisci indicate that degenerative changes in patients with MMPRTs extend beyond the immediate vicinity of the posterior root tear. This suggests more widespread meniscal degeneration, often undetected by surface examinations in arthroscopy.

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

INTRODUCTION:  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. MATERIALS AND METHODS:  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. RESULTS: 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. CONCLUSION:  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.

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

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.

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.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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 OF EVIDENCE: Level IV.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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 OF EVIDENCE: Level IV.

Differences Between Traumatic and Degenerative Medial Meniscus Posterior Root Tears: A Systematic Review.

BACKGROUND: Intact meniscus roots are a prerequisite for normal meniscal function, including even distribution of compressive forces across the knee joint. An injury to the root disrupts the hoop strength of the meniscus and may lead to its extrusion and the development of osteoarthritis. A medial meniscus posterior root tear (MMPRT) is often thought to have a primary degenerative pathogenesis. However, there is mention of some cases of MMPRTs where the patients have a solely traumatic injury to a previously healthy meniscus. PURPOSE: To describe a subpopulation of patients with traumatic MMPRT. STUDY DESIGN: Systematic review; Level of evidence, 5. METHODS: The Web of Science database (www.webofscience.com) was queried using the Medical Subject Headings term "medial root tear." Articles were reviewed, and those evaluated for MMPRTs in a degenerative meniscus were excluded. A total of 25 articles describing cases of acute traumatic causes were included in this study. For these articles, the patient characteristics, injury mechanisms, and concomitant injuries evaluated were recorded and pooled. RESULTS: The search revealed 660 articles, and 25 were selected for inclusion. A total of 113 patients with a traumatic MMPRT were identified and included in this review. The study population had a mean age of 27.1 years and a high share of men (64%). Also, this review displays how most patients with traumatic MMPRTs also suffer concomitant injuries (68%). CONCLUSION: The findings in this review support our hypothesis that there is a unique subgroup with acute traumatic MMPRTs that have unique patient characteristics, injury mechanisms, and combined injuries, compared with previously published reviews on MMPRTs.

Biomechanical Performance of Transtibial Pull-Out Posterior Horn Medial Meniscus Root Repair Is Improved With Knotless Adjustable Suture Anchor-Based Fixation.

Background: While posterior medial meniscus root (PMMR) techniques have evolved, there remains a need to both optimize repair strength and improve resistance to cyclic loading. Hypothesis: Adjustable tensioning would lead to higher initial repair strength and reduce displacement with cyclic loading compared with previously described transtibial pull-out repair (TPOR) fixation techniques. Study Design: Controlled laboratory study. Methods: A total of 56 porcine medial menisci were used. Eight intact specimens served as a control for the native meniscus. For the others, PMMR tears were created and repaired with 6 different TPOR techniques (8 in each group). Fixed PMMR repairs were executed using 4 different suture techniques (two No. 2 cinch sutures, two cinch tapes, two No. 2 simple sutures, and two No. 2 sutures in a Mason-Allen configuration) all tied over a cortical button. Adjustable PMMR repairs using Mason-Allen sutures were fixed with an adjustable soft tissue anchor fixation tensioned at either 80 N or 120 N. The initial force, stiffness, and relief displacement of the repairs were measured after fixation. Repair constructs were then cyclically loaded, with cyclic displacement and stiffness measured after 1000 cycles. Finally, the specimens were pulled to failure. Results: The PMMR repaired with the 2 cinch sutures fixed technique afforded the lowest (P < .001) initial repair load, stiffness, and relief displacement. The adjustable PMMR repairs achieved a higher initial repair load (P < .001) and relief displacement (P < .001) than all fixed repairs. The 2 cinch sutures fixed technique showed an overall higher cyclic displacement (P < .028) and was completely loose compared with the native meniscus functional zone. Repairs with adjustable intratunnel fixation showed displacement with cyclic loading similar to the native meniscus. With cyclic loading, the Mason-Allen adjustable repair with 120 N of tension showed less displacement (P < .016) than all fixed repairs and a stiffness comparable to the fixed Mason-Allen repair. The fixed Mason-Allen technique demonstrated a higher ultimate load (P < .007) than the adjustable Mason-Allen techniques. All repairs were less stiff, with lower ultimate failure loads, than the native meniscus root attachment (P < .0001). Conclusion: Adjustable TPOR led to considerably higher initial repair load and relief displacement than other conventional fixed repairs and restricted cyclic displacement to match the native meniscus function. However, the ultimate failure load of the adjustable devices was lower than that of a Mason-Allen construct tied over a cortical button. All repair techniques had a significantly lower load to failure than the native meniscus root. Clinical Relevance: Knotless adjustable PMMR repair based on soft anchor fixation results in higher tissue compression and less displacement, but the overall clinical significance on healing rates remains unclear.

Item-Specific Knee Injury and Osteoarthritis Outcome Score Characterization of Patients With Medial Meniscus Root Tear.

Background: Most studies regarding medial meniscus posterior root tear (MMPRT) report total Knee injury and Osteoarthritis Outcome Score (KOOS) subscale values as important patient-reported outcomes, but there are few symptom-specific characterizations of patients with MMPRT. Purpose/Hypothesis: The purpose of this study was to characterize the prevalence and severity of symptoms and functional limitations among patients with MMPRT based on item-level KOOS responses. It was hypothesized that patients with MMPRT would show similar symptoms to those of other meniscal tear types, with items from the KOOS pain subscale forming a majority of the most severe and prevalent symptoms. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The records of 1466 patients with medial meniscus root tear between January 2017 and December 2021 at a single institution were reviewed. KOOS subscale scores and item-specific responses from initial evaluation were collected for each patient. Each KOOS item was scored on a scale from 1 (none/least severe) to 5 (extreme/most severe). Median and mean item-level responses were calculated and ranked in order of most to least severe. For statistical analysis, item-level prevalence rates were calculated as the proportion of patients reporting at least mild symptoms and ranked from most to least prevalent. Results: Included were 61 patients with MMPRT verified on magnetic resonance imaging (MRI). The most severe items according to item-level KOOS response were as follows: awareness of knee problem (mean, 4.62 [95% CI, 4.47-4.78]), difficulty jumping (mean, 4.06 [95% CI, 3.73-4.39]), difficulty twisting or pivoting (mean, 4.04 [95% CI, 3.76-4.32]), difficulty kneeling (mean, 3.98 [95% CI, 3.65-4.31]), and modification of lifestyle (mean, 3.94 [95% CI, 3.69-4.20]). The most prevalent items were knee stiffness later in the day, pain going up- or downstairs, difficulty ascending stairs, difficulty getting in and out of the car, difficulty twisting or pivoting, awareness of knee problem, and modification of lifestyle, with all patients reporting at least mild symptoms for each. Of the 11 most severe and prevalent symptoms, 8 came from the KOOS-Pain item-specific responses. Conclusion: Pain-related items made up a majority of the most severe and most prevalent symptoms as identified by the item-specific KOOS responses. However, meniscal symptoms commonly seen in other tear types, such as clicking and knee stiffness, were still quite prevalent in patients with MMPRT.

Medial Meniscus Posterior Root Reconstruction and Open-Wedge High-Tibial Osteotomy for Medial Meniscus Posterior Root Tear With Varus Knee Alignment: A Retrospective Study on Short-Term Outcomes.

PURPOSE: We describe 13 cases of medial meniscus posterior root tear (MMPRT) with varus knee alignment treated with medial meniscus posterior root reconstruction (MMPR-R) and open-wedge high-tibial osteotomy (OWHTO) to identify an optimal MMPRT treatment. METHODS: We retrospectively reviewed 13 patients (mean age: 66.3 ± 8.0 years) who underwent MMPR-R and OWHTO. The Knee Injury and Osteoarthritis Outcome Score (KOOS), femorotibial angle (FTA), percentage mechanical axis (%MA) on radiography, and medial meniscus extrusion (MME) on magnetic resonance imaging (MRI) between the preoperative period and last follow-up were compared. Moreover, meniscus healing status and the International Cartilage Repair Society (ICRS) classification of the medial femoral condyle and medial tibial plateau on arthroscopy between the initial surgery and second-look arthroscopy were compared. RESULTS: The mean follow-up duration was 12.8 ± 2.2 months. At the last follow-up, the KOOS significantly improved (P < 0.01). Based on the FTA and %MA, the varus alignment was predominantly corrected at the last follow-up (P < 0.01). The MME was increased in nine (62.9%) patients, and the mean MME significantly increased at the last follow-up (P = 0.04). Second-look arthroscopy revealed improvements in the ICRS grade for the medial femoral condyle and medial tibial plateau in six (46.2%) patients. However, the results did not significantly differ. Regarding meniscus healing, four (30.8%) patients presented with complete healing, eight (57.1%) with partial healing, and one (7.7%) with failed healing. CONCLUSIONS: The MMPRT with varus knee alignment significantly improved with MMPR-R and OWHTO. However, the MME and meniscus healing were unsatisfactory.

Reconstruction of medial meniscus posterior portion deficiency in pigs with an autologous patellar tendon graft: an experimental study.

OBJECTIVE: This study was performed to investigate the effectiveness of two surgical procedures, autologous patellar tendon graft reconstruction and trans-tibial plateau pull-out repair, using a pig model. The primary focus was to assess the repair capability of medial meniscus posterior portion (MMPP) deficiency, the overall structural integrity of the meniscus, and protection of the femoral and tibial cartilage between the two surgical groups. The overall aim was to provide experimental guidelines for clinical research using these findings. METHODS: Twelve pigs were selected to establish a model of injury to the MMPP 10 mm from the insertion point of the tibial plateau. They were randomly divided into three groups of four animals each: reconstruction (autologous tendon graft reconstruction of the MMPP), pull-out repair (suture repair of the MMPP via a trans-tibial plateau bone tunnel), and control (use of a normal medial meniscus as the negative control). The animals were euthanized 12 weeks postoperatively for evaluation of the meniscus, assessment of tendon bone healing, and gross observation of knee joint cartilage. The tibial and femoral cartilage injuries were evaluated using the International Society for Cartilage Repair (ICRS) grade and Mankin score. Histological and immunohistochemical staining was conducted on the meniscus-tendon junction area, primary meniscus, and tendons. The Ishida score was used to evaluate the regenerated meniscus in the reconstruction group. Magnetic resonance imaging (MRI) was used to evaluate meniscal healing. RESULTS: All 12 pigs recovered well after surgery; all incisions healed without infection, and no obvious complications occurred. Gross observation revealed superior results in the reconstruction and pull-out repair groups compared with the control group. In the tibial cartilage, the reconstruction group had ICRS grade I injury whereas the pull-out repair and control groups had ICRS grade II and III injury, respectively. The Mankin score was significantly different between the reconstruction and control groups; histological staining showed that the structure of the regenerated meniscus in the reconstruction group was similar to that of the original meniscus. Immunohistochemical staining showed that the degree of type I and II collagen staining was similar between the regenerated meniscus and the original meniscus in the reconstruction group. The Ishida score was not significantly different between the regenerated meniscus and the normal primary meniscus in the reconstruction group. MRI showed that the MMPP in the reconstruction and pull-out repair groups had fully healed, whereas that in the control group had not healed. CONCLUSION: Autologous patellar tendon graft reconstruction of the MMPP can generate a fibrocartilage-like regenerative meniscus. Both reconstruction and pull-out repair can preserve the structural integrity of the meniscus, promote healing of the MMPP, delay meniscal degeneration, and protect the knee cartilage.

High-resolution magnetic resonance imaging can predict osteoarthritic progression after medial meniscus posterior root injury: randomized in vivo experimental study in a rabbit model.

IMPORTANCE: The field of meniscal root preservation has undergone significant advancement over the past decades; however, the challenge remains to fully understand whether meniscal root repair can ultimately arrest or delay osteoarthritic changes. OBJECTIVE: To assess longitudinal changes in articular cartilage, subchondral bone, and progression to meniscal extrusion (ME) using high-resolution magnetic resonance imaging (MRI). METHODS: Medial meniscus posterior root tear was surgically induced in 39 New Zealand white rabbits. Animals were randomly assigned into three experimental groups: partial meniscectomy after root tear (PM, n â€‹= â€‹13); root tear left in situ (CT, n â€‹= â€‹13); and transtibial root repair (RR, n â€‹= â€‹13). Contralateral limbs were used as healthy controls. High resolution 4.7 Tesla MRI of the knee joint was performed at baseline, after 2-, and 4-months of post-surgery. Cartilage thickness was calculated in medial and lateral compartments. In addition, the evaluation of ME, subchondral bone edema and healing potential after root repair were assessed too. RESULTS: Progressive cartilage thinning, ME, and subchondral bone edema were evident in all 3 study groups after 4-months of follow-up. The mean cartilage thickness in the PM group was 0.53 â€‹mm (±0.050), 0.57 â€‹mm (±0.05) in the CT group, and 0.60 â€‹mm (±0.08) in the RR group. The PM group exhibited significantly higher cartilage loss when compared to the CT and RR groups (p â€‹< â€‹0.001). Moreover, progressive ME and subchondral bone edema were associated with a more severe cartilage loss at the final follow-up. CONCLUSION: Meniscal root repair did not halt but rather reduced the progression of osteoarthritis (OA). Degenerative changes worsened at a rapid rate in the PM group compared to the RR and CT groups. Early cartilage swelling, persistent subchondral edema, and progressive ME predicted a more severe progression to knee OA in the CT and RR groups. LEVEL OF EVIDENCE: II.

Association of Increased Lateral Femoral Condylar Ratio With Lateral Meniscus Posterior Root Tear in Noncontact ACL Injury.

Background: In the setting of anterior cruciate ligament (ACL) injury, lateral meniscus posterior root tears (LMPRTs) are less readily diagnosed on preoperative magnetic resonance imaging (MRI). Therefore, to predict LMPRTs in ACL injuries, it is necessary to understand the risk factors associated with them. Purpose/Hypothesis: The purpose of this study was to investigate the association of lateral femoral condylar ratio (LFCR) with LMPRTs in ACL injuries. It was hypothesized that an increased LFCR would be associated with LMPRTs in noncontact ACL injuries. Study Design: Cohort study; Level of evidence, 3. Methods: Enrolled were consecutive patients who underwent primary acute (<6 weeks from injury) ACL reconstruction after noncontact injury and had LMPRT confirmed on preoperative MRI and arthroscopically (combined group; n = 62) as well as patients who underwent isolated acute ACL reconstruction (isolated group; n = 80) who were matched to the combined group by age, height, and body mass index (BMI). All patients underwent surgery between January 1999 and November 2021. LFCR and posterior tibial slope (PTS) were measured and compared between the isolated and combined groups. The area under the receiver operating characteristic curve (AUC) was calculated to determine the cutoff for detecting increased risk of LMPRTs. Results: The demographic characteristics of the 2 groups did not differ significantly, nor did the PTS. The LFCR was a significant factor (odds ratio [OR], 1.23; P = .001) associated with LMPRT. Patient age, height, BMI, and PTS were not associated with LMPRT. The AUC (0.66; 95% CI, 0.57-0.75) for LFCR had a sensitivity of 39% and specificity of 90% to predict LMPRT. The calculated cutoff associated with an increased risk for LMPRT when compared with the isolated group was 67.0% (OR, 4.98; 95% CI, 2.10-11.79). Conclusion: Increased LFCR was associated with the presence of LMPRTs in patients with acute ACL injuries. The LFCR may provide surgeons with additional information regarding the risk of having a concomitant LMPRT when planning ACL reconstructions.

[Research progress on pathological mechanism and clinical correlation between medial meniscus posterior root tear and tibial rotation].

Objective: To summarize the current research progress on the concept, clinical presentation, diagnosis, biomechanical changes, and pathological mechanisms of the medial meniscus posterior root tear (MMPRT), and its clinical correlations with tibial rotation. Methods: The research literature on MMPRT and its relationship with tibial rotation at home and abroad in recent years was extensively consulted and summarized. Results: MMPRT is a specific and common type of medial meniscus injury of the knee joint. The occurrence of posterior medial pumping pain events following low-energy trauma in patients provides important clues for the diagnosis of this injury, with MRI being the preferred imaging modality. The biomechanical effects generated by MMPRT are similar to those caused by total removal of the medial meniscus. And this injury is usually associated with tibial rotation. MMPRT induces pathological external rotation of the tibia, which can be restored by timely medial meniscus posterior root repair. Furthermore, changes in tibial rotation are related to the healing status after medial meniscus posterior root repair. Conclusion: MMPRT is closely related to tibial rotation. Understanding the biomechanics, pathological mechanisms, and clinical correlations between the two is of great significance for improving the diagnosis and treatment strategies.

[Meniscus update]. / Update Meniskus.

Meniscus tears are classified as horizontal, longitudinal, radial, and complex tears. Flap tears are a specific form in which a portion of the meniscus is displaced from a horizontal or longitudinal tear. The question of whether it is possible to preserve the meniscus by meniscus repair is of crucial therapeutic importance. It is therefore important to specify not only the configuration of the tear but also its extent and location as precisely as possible. Cooper's zonal classification should also be used for this purpose. Lesions of the meniscus roots are of high clinical relevance. On the posterior horn of the medial meniscus, root lesions are usually degenerative; on the posterior horn of the lateral meniscus, they are often traumatic. It is important to familiarize oneself with the normal appearance and anatomical location of the meniscal roots. Ramp lesions have received particular attention in recent years, especially in patients with anterior cruciate ligament tears. Therefore, particularly the integrity of the attachment of the posterior horn of the medial meniscus to the tibial plateau must be analyzed. If the meniscotibial ligament tears along its course or at the insertion to the meniscus or if it avulses with a meniscus fragment, this is a ramp lesion.

Favorable early outcomes of medial unicompartimental knee arthroplasty in active patients presenting a degenerative medial meniscus root tear with meniscal extrusion and mild radiographic osteoarthritis.

INTRODUCTION: There is only limited literature available evaluating the preferable treatment for active mid-age or elderly patients presenting with a degenerative medial meniscus root tear (d-MMRT) with medial meniscal extrusion (MME) and early-phase radiographic osteoarthritis (OA), failing to provide solid evidence. The aim of this study was to evaluate early outcomes of medial unicompartimental arthroplasty (mUKA) in active patients presenting a d-MMRT with meniscal extrusion and mild radiographic OA of the knee. To prove this claim we hypothesized that (1) patients with a d-MMRT with initial grade 1-3 KL OA of the medial compartment of the knee present the same pre-operative symptoms as patients with an end-stage grade 4 K-L OA, and that (2) those patients with d-MMRT and low-grade OA achieve the same early clinical and functional outcomes when treated with mUKA compared to patients with end-stage medial OA. METHODS: We reviewed the prospectively collected data of 185 patients undergoing robotic-assisted image-based mUKA from January 2021 to July 2022 at a single Institution. We identified two different cohorts of non-consecutive patients: a group of 24 patients undergoing mUKA surgery following d-MMRT combined with K-L grades 1-3 OA (group 1), and a group of 161 patients who underwent mUKA but presenting with an end-stage bone-on-bone K-L grade 4 OA (group 2). Preoperative and postoperative clinical assessments at one-year follow-up included the Oxford Knee Score (OKS), 5-level EQ-5D version (EQ-5D-5L score), and a standard weight-bearing X-ray protocol. The paired t-test was used to compare clinical outcomes and radiologic values of the two cohorts and in-between the two cohorts. Statistical significance was set at p < 0.05. RESULTS: The mean follow-up for group 1 was 16.4 ± 2.5 months, and the mean age at the time of operation was 63 ± 8.6 years with a mean time from diagnosis to intervention of 53 ± 47.5 days. Preoperative impairment was greater in group 1 compared to group 2, but with no significant difference. Postoperatively, both groups showed excellent mean outcomes at 1-year follow-up, with no significant difference. The mean preoperative HKA, mPTA, and LDFA were 176.3 ± 3.1, 88.1 ± 2.3, and 86.6 ± 1.7 respectively. The mean postoperative HKA, coronal femoral component angle, and coronal tibial component angle were 179.1 ± 2.6, 87.2 ± 2.3, and 87.2 ± 3.3. No difference was found between preoperative age, BMI, between the two cohorts. CONCLUSIONS: Favorable early clinical outcomes were obtained after mUKA in active mid-age and elderly patients presenting with degenerative medial meniscus root tear and mild isolated medial OA. Patients with mild no bone-on-bone OA but with degenerative medial meniscus root tear and medial meniscal extrusion presented the same or worse pre-operative symptoms as patients with end-stage medial OA and benefit the same from mUKA.

Signal intensity of repaired posterior roots after transtibial pullout repair for medial meniscus posterior root tears in stable knees: Magnetic resonance imaging evaluations at 3 years postoperatively.

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.

Longitudinal changes in medial meniscus extrusion and clinical outcomes following pullout repair for medial meniscus posterior root tears: a 3-year evaluation.

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.

Assessing the Frequency and Effectiveness of Various Arthroscopic Treatments in the Management of Symptomatic Isolated Medial Meniscus Injuries Including Medial Meniscus Posterior Root Tear: A Retrospective Observational Cohort Study.

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.

Superior outcomes of pullout repairs for medial meniscus posterior root tears in partial tear compared to complete radial tear.

PURPOSE: To reveal the outcomes of partial medial meniscus posterior root tears following transtibial pullout repair compared with the outcomes of complete radial meniscus posterior root tears. MATERIALS AND METHODS: We retrospectively evaluated 15 consecutive patients (male/female, 5/10; average age, 64.4 years) who underwent transtibial pullout repair for partial medial meniscus posterior root tears and compared their results with those of 86 consecutive patients who underwent the same surgery for complete medial meniscus posterior root tears. All patients underwent second-look arthroscopy on average 1 year postoperatively, and a semi-quantitative meniscal healing score (anteroposterior width, stability, and synovial coverage, total 10 points) was evaluated. Medial meniscus extrusion was evaluated preoperatively and at second-look arthroscopy. RESULTS: Postoperative clinical scores were not significantly different in the short term. However, second-look arthroscopy revealed a significant difference in repaired meniscal stability (partial tear; 3.3 points, complete tear; 2.3 points, p < 0.001) and total meniscal healing scores (partial tear; 8.3 points, complete tear; 7.1 points, p < 0.001). Medial meniscus extrusion progression was significantly different (partial tear; 0.4 mm, complete tear; 1.0 mm, p < 0.001). CONCLUSION: Partial medial meniscus posterior root tears showed better meniscal healing and less medial meniscus extrusion progression following pullout repair than complete medial meniscus posterior root tears.