Meniscal Root Attachment Research Articles

Medial meniscal posterior root tear – A current concept review

Menisci are crucial structures in the knee joint for the adequate distribution of hoop stresses. Their significance in preventing early knee osteoarthritis has been acknowledged due to the rapid progression of osteoarthritis in knees following meniscectomy. The anatomy of menisci has been studied in detail with an increased understanding of the importance of meniscal root attachments. This review aims to provide an evaluated summary of the anatomical, biochemical, and functional aspects that are relevant in the clinical context of meniscus root attachments, alongside contemporary strategies for accurately diagnosing and treating common injuries affecting these attachments. We also propose an algorithm for managing medial meniscus root tears which may be beneficial for the readers. We did an up-to-date literature search on PubMed, Scopus, and Google Scholar database, using the keywords ‘meniscus’, ‘meniscal root’, ‘sports injury’, and ‘arthroscopy’ in April 2024 and filtered out the relevant literature for this review on the articles that were published in English. The management of root tears requires a high level of suspicion which is crucial for diagnosis, identifying subtle signs on radiology, and employing specific methods for root repair. The tears or avulsions within one centimeter of the tibial attachment of the medial meniscus posterior root are called medial meniscus posterior root tears. These injuries cause a functional meniscal deficiency, resulting in knee problems unfavorable to biomechanics. Numerous methods have been created to tackle meniscus root tears., with many demonstrating promising outcomes in terms of complete healing.

MENISCAL ANOMALIES IN CONGENITAL CRUCIATE LIGAMENT DEFICIENCY: EXPERIENCE IN A TERTIARY CHILDREN'S KNEE UNIT

ObjectivesCongenital cruciate ligament deficiency is a rare condition that may occur in isolation or in association with longitudinal limb deficiencies such as fibular hemimelia or proximal femoral focal deficiency. Often anomalies of the menisci and their attachments can be very abnormal and impact on surgical management by standard techniques. Arthroscopic surgical knee reconstruction is undertaken to improve symptomatic instability and/or to stabilise and protect the knee for future planned limb lengthening surgery.The aim of this study is to evaluate the arthroscopic findings of patients undergoing surgery for congenital cruciate ligament deficiency, and specifically to determine the frequency and types of meniscal anatomical variations seen in these cases.MethodsPatients undergoing surgery for congenital cruciate ligament deficiency were identified from a prospectively collated database. Diagnosis was confirmed through review of the clinical notes and imaging. Operative notes and 4K saved arthroscopic images and video recordings for these cases were reviewed.ResultsOver a six-year period (July 2017 – September 2023), 42 patients underwent surgery for congenital ligament deficiency and tibiofemoral instability (45 surgical episodes). Median age of patients at time of surgery was 10 years (range 4 – 17 years). The most frequent diagnosis was congenital longitudinal limb deficiency syndromes in 27 cases, with the most frequent being fibular hemimelia. Isolated congenital ligament deficiency without any other associated extra-articular manifestations occurred in 11 cases. Absence of meniscal root attachments or hypertrophy of meniscofemoral ligaments acting as ‘pseudo-cruciates’ were seen in over 25% of patients. In isolated ACL deficiency these were injured causing onset of instability symptoms and pain following trauma. Often these abnormal structures required addressing to allow surgical reconstruction.ConclusionsOur findings demonstrate that there are often meniscal variations seen in association with congenital absence or hypoplasia of the cruciate ligaments. In these patients hypertrophied meniscofemoral ligaments may act as cruciate-like structures and play a role in providing a degree of sagittal plane stability to the knee. However, when the knee becomes unstable to the point that cruciate ligament reconstruction is indicated, these meniscal variants may often require stabilisation using complex meniscal root repair techniques or variations to standard cruciate ligament reconstruction techniques to accommodate the variant anatomy.

A balance between native footprint coverage and overlap of the anterolateral meniscal root in tibial tunnel positioning during anterior cruciate ligament reconstruction: A 3D MRI study

BackgroundTibial footprint of anterior cruciate ligament (ACL) is situated close to the anterior lateral meniscal root (ALMR) attachment. PurposeTo investigate the impact of the size and location of the tibial tunnel for ACL reconstruction on the ACL footprint coverage and overlap to the ALMR. Study designControlled laboratory study. MethodsTwenty knee MRI scans from twenty healthy subjects were recruited, and three-dimensional (3D) tibia models were created to show the tibial attachment sites of ACL and ALMR. Surgical simulation of the tibial tunnel drilling was performed on each 3D model, entering the joint at an angle set at 60 degrees from the tibial plateau plane and 55 degrees from the posterior tibial condylar axis, with analysis for six different drill sizes; 7.5, 8, 8.5, 9, 9.5 and 10 mm; and nine locations; the center of the ACL attachment and eight locations 2% of the tibial width apart surrounding it. The width of the tibial plateau, the distance between ACL and ALMR attachment centers, and the size and location of the potential tibial tunnel were evaluated to determine association with the area of the ACL footprint coverage and ALMR overlap using a linear mixed effects model. ResultsA large tunnel (p <.001), a central and anterior location (p <.029), and small tibial width (p =.015) were all associated with larger coverage of the ACL footprint. A large tunnel (p <.001), posteriorly and laterally located (p ≤ 0.001), and a small distance between the ACL and ALMR centers (p =.001) were significantly associated with a larger ALMR overlap. The association of the tunnel size to ALMR overlap reduced with a medial tunnel location. ConclusionsThe short distance between the centers of the ALMR attachment and native ACL footprint suggests that the ALMR will always be susceptible to overlap when the tibial tunnel is drilled in ACL reconstruction. Small alterations in tunnel location can lead to a statistically significant alteration with the amount of ALMR overlap. To minimize this overlap, whilst maintaining acceptable coverage of the ACL footprint, a tibial tunnel positioned in a medial or anteromedial location from the center of the ACL footprint is recommended.

Arthroscopic Medial Meniscus Root Repair With Transtibial Ripstop Technique

Background: Meniscal root tears are radial tears occurring at or within 1 cm of the meniscal root attachment. These injuries have been shown to be the biomechanical equivalent of a total meniscectomy and are thought to be responsible for a rapid progression of osteoarthritis if left untreated. Indications: Meniscal root repair is indicated if possible, with the exception of patients who have diffuse Outerbridge 3-4 osteoarthritis of the ipsilateral compartment, those who are poor surgical candidates due to age or medical comorbidity, or in whom nonsymptomatic tears are found incidentally. Technique Description: Standard 2-portal arthroscopy is performed. Once a medial root tear has been identified and concomitant pathology has been addressed, we typically begin the repair by trephinating the deep medial collateral ligament with an 18-gauge needle to enhance visualization and avoid iatrogenic cartilage injury. Arthroscopic shaver is used to debride the meniscal root as needed. A meniscal root guide is introduced into the joint and an incision is made on the anteromedial tibia for outside-in drilling of a transosseous tunnel. Drilling is performed with a 5-mm retroreaming device, and a 10-mm socket is created. Nonabsorbable suture is then passed through the meniscus using a self-capture device in an inverted mattress configuration, following by 2 cinch stitches. The sutures are then shuttled into the transosseous tunnel, and the meniscal root is reduced and tensioned in full extension, with the sutures being fixated into a suture anchor on the anteromedial tibia. Results: A recent large systematic review of 1086 patients undergoing treatment of meniscal root tear via either debridement or nonoperative management compared with meniscal repair found that conversion to total knee arthroplasty occurred in 11% to 54% of those managed via debridement or nonoperative care versus 0% to 1% for those with root repair. Discussion/Conclusion: Currently, meniscal root repair offers the greatest improvement and lowest risk of conversion to arthroplasty following meniscal root tear. The present technique offers a durable repair that we believe combines ease of execution with decreased risk of suture pull-out, by creating a ripstop-type construct. Long-term outcome studies are needed for this and other root repair techniques.

The effects of different repair methods for a posterior root tear of the lateral meniscus on the biomechanics of the knee: a finite element analysis

PurposeTo explore the impact of different repair methods for a lateral meniscus posterior root tear on the biomechanics of the knee joint using finite element analysis.MethodsFinite element models of a healthy knee were established on the basis of MRI data from a volunteer using Mimics software, and the validity of the models was tested. The changes in the contact mechanics and kinematics of these finite element models under different repair approaches were then analyzed and compared.ResultsThe normal meniscus had the maximum joint contact area, the minimum contact pressure, and the minimum contact stress. When total meniscectomy of the lateral meniscus was performed, the lateral compartment had the minimum joint contact area, the maximum contact pressure and the maximum contact stress. When complete avulsions of the posterior root of the lateral meniscus occurred, the maximum values of contact pressure and contact stress were between those of an intact meniscus and those of a meniscus treated with total meniscectomy. Lateral meniscal root attachment reconstruction by the single-stitch and double-stitch techniques resulted in a significant decrease in joint contact pressure and contact stress, leading to values comparable to those of a normal knee joint, and the double-stitch technique performed better than the single-stitch technique.ConclusionsRepair surgery for lateral meniscal posterior root avulsions can effectively restore the contact mechanics and kinematics of the knee joint, and the double-stitch technique can result in better clinical outcomes than the single-stitch technique.

The PCL Envelope Lack Sign (PELS) Is a Direct Arthroscopic Sign of Chronic Posterior Cruciate Ligament Insufficiency

Purpose: To present the arthroscopic “PCL envelope lack sign” (PELS) and to calculate its diagnostic characteristics in chronic PCL insufficiency. Methods: Recordings of knee arthroscopies performed in a single clinic between April 2015 to March 2020 were retrospectively evaluated, searching for the “PCL envelope”. It was defined as a “soft tissue cuff coursing around the PCL tibial attachment, visible with the arthroscope positioned between the PCL, medial femoral condyle and posterior horn of the medial meniscus at the level of its shiny white fibers”. PELS was defined as “the PCL adhering to the proximal tibia adjacent to the medial meniscal posterior root attachment, inability to observe the normal space between the PCL and posterior tibia and no soft tissue cuff around the PCL tibial attachment”. Inclusion criteria were possibility to evaluate the PELS presence on recordings. Patients who underwent PCL reconstruction were assigned to the study group. The rest of the patients were controls. Criteria to operate on symptomatic PCL patients were at least 5 mm of posterior instability in physical examination and at least 6 months post-injury. Results: Out of 614 available recordings, 592 patients (205 females, 387 males; mean age 45.2 years, SD = 14.36, range 14–81) were included: 38 in the study group and 554 in the control group. In the study group, PELS was positive in 36 of 38 cases (94.7%). In the control group, PELS was negative in 554 PCL-efficient patients (100%). Calculated PELS sensitivity was 94.7%, specificity 100%, positive predictive value 100%, negative predictive value 99.6%. The PELS was present significantly more often in PCL-insufficient patients, p &lt; 0.001. Conclusions: The PCL envelope lack sign was found to be a highly effective tool to arthroscopically confirm chronic PCL insufficiency, and should be considered a direct sign of chronic posterior knee instability.

Degeneration Affects Three-Dimensional Strains in Human Menisci: In situ MRI Acquisition Combined With Image Registration.

Degenerative changes of menisci contribute to the evolution of osteoarthritis in the knee joint, because they alter the load transmission to the adjacent articular cartilage. Identifying alterations in the strain response of meniscal tissue under compression that are associated with progressive degeneration may uncover links between biomechanical function and meniscal degeneration. Therefore, the goal of this study was to investigate how degeneration effects the three-dimensional (3D; axial, circumferential, radial) strain in different anatomical regions of human menisci (anterior and posterior root attachment; anterior and posterior horn; pars intermedia) under simulated compression. Magnetic resonance imaging (MRI) was performed to acquire image sequences of 12 mild and 12 severe degenerated knee joints under unloaded and loaded [25%, 50% and 100% body weight (BW)] conditions using a customized loading device. Medial and lateral menisci as well as their root attachments were manually segmented. Intensity-based rigid and non-rigid image registration were performed to obtain 3D deformation fields under the respective load levels. Finally, the 3D voxels were transformed into hexahedral finite-element models and direction-dependent local strain distributions were determined. The axial compressive strain in menisci and meniscal root attachments significantly increased on average from 3.1% in mild degenerated joints to 7.3% in severe degenerated knees at 100% BW (p ≤ 0.021). In severe degenerated knee joints, the menisci displayed a mean circumferential strain of 0.45% (mild: 0.35%) and a mean radial strain of 0.41% (mild: 0.37%) at a load level of 100% BW. No significant changes were observed in the circumferential or radial directions between mild and severe degenerated knee joints for all load levels (p > 0.05). In conclusion, high-resolution MRI was successfully combined with image registration to investigate spatial strain distributions of the meniscus and its attachments in response to compression. The results of the current study highlight that the compressive integrity of the meniscus decreases with progressing tissue degeneration, whereas the tensile properties are maintained.

Three-dimensional computed tomography confirmed that the meniscal root attachments and meniscofemoral ligaments are morphologically consistent.

To clarify the characteristic features of the meniscal root attachments, meniscofemoral ligaments (MFLs), and related osseous landmarks on three-dimensional images using computed tomography. Twenty-eight non-paired, formalin-fixed human cadaveric knees were evaluated in this study. The meniscal root attachments were identified and marked. Three-dimensional images were obtained after applying a contrast agent to the entire meniscal surfaces and MFLs, then the morphology of the meniscal root attachments and MFLs, and their positional relationships with osseous landmarks, were analyzed. Parsons' knob divided the medial meniscal anterior root attachment and lateral meniscal anterior root attachment on the anterior portion of the tibial plateau. The medial meniscal posterior root attachment was near the medial intercondylar tubercle. The lateral meniscal posterior root attachment (LMPRA) was closer to the lateral intercondylar tubercle. Both root attachments were near the posterior intercondylar fossa. The positional relationships between the meniscal root attachments and related osseous landmarks were consistent in all specimens. The MFLs originated from the lateral meniscus posterior horn, and the anterior MFL was closer to the LMPRA than the posterior MFL. The posterior MFL originated at approximately the midpoint between the LMPRA and the most posterior margin of the lateral meniscus. This study showed that the relationships between the characteristic features of the meniscal root attachments, MFLs, and related osseous landmarks were consistent. The clinical relevance of this study is that it improved understanding of the anatomy of the meniscal root attachments and MFLs.

The distance between the tibial tunnel aperture and meniscal root attachment is correlated with meniscal healing status following transtibial pullout repair for medial meniscus posterior root tear

BackgroundTo investigate the relationship between tibial tunnel aperture location and postoperative meniscal healing. MethodsWe 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. ResultsThe AC–TC distance and meniscal healing score were significantly associated (y = −0.42x + 9.48, R2 = 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%. ConclusionsThis 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.

Knotless Anchor Fixation for Transosseous Meniscal Root Repair Using Suture Tape Is Inferior Compared With Button or Screw Fixation: A Biomechanical Study.

Background:A 2 mm–wide ultrahigh-molecular-weight polyethylene (UHMWPE) tape improves the contact pressure at root repair sites compared with high-strength suture and provides a stronger repair construct. UHMWPE tape is commonly used in rotator cuff repair, and fixation is often achieved with knotless suture anchors. The optimal method for tape fixation for meniscal root repair has not been established.Hypothesis:The use of suture anchors for the tibial fixation of 2-mm UHMWPE tape transosseous root repairs will lead to better biomechanical performance compared with other fixation methods.Methods:The medial meniscal posterior root attachment in 25 porcine knees was divided, and a standardized transtibial root repair was performed using 2-mm UHMWPE tape. The testing was performed by cyclic loading followed by load to failure. Tibial fixation was randomized to 5 tibial fixation types: (1) cortical fixation button, (2) pound-in suture anchor with screw-down interference suture locking, (3) tap-in suture anchor with inner locking plug, (4) postscrew, and (5) postscrew and washer.Results:There was no difference in displacement during cyclic loading between tibial fixation groups except for a highly significant difference in the maximum load at failure. Repairs in both suture anchor fixation groups all failed by tape slippage at relatively low loads (median, 145 and 116 N, respectively). Repairs tied over a cortical button, postscrew, or screw and washer failed by tape breakage at loads of 431, 405, and 528 N.Conclusion:For meniscal root repairs with 2-mm UHMWPE tape, use of suture anchors offers weaker fixation compared with tying over a button or postscrew/washer. While suture anchor fixation may be adequate for nonweightbearing postoperative protocols, it may not allow for more accelerated weightbearing.

Meniscus Root Repair

Meniscal root tears defined as bony or soft tissue root avulsion injuries or radial tears within 1cm of the meniscal root attachment. If it is not treated properly can cause early development of osteoarthritis. The meniscal root tears leading to compromised hoop stress and decreased tibiofemoral contact area and increased contact pressures in the involved compartment. To confirm the diagnosis is through arthroscopic as a diagnostic and treatment and through magnetic resonance imaging. Not all meniscal root tears can be treated surgically, especially if they have multiple comorbidities or advanced age, severe osteoarthritis, non-symptomatic chronic meniscal root tears and significant mal-alignment of the affected compartment then the treatment of choice is to give a symptomatic treatment like non-steroid anti-inflammatory drug, and activity modification. Meniscectomy has been found to induce a high rate of arthritis progression postoperatively. There are two most common meniscal root repair techniques which are trans-tibial pullout repair and suture anchor repair that now preferred over meniscectomy. The most important thing to consider when repairing the meniscal root is the right anatomically repair. It has been proven that non-anatomical meniscal root repair will not able to restore to the normal function because the conversion of femorotibial loads into circumferential tension may be altered, with functional impairment of the knee. Anchor suture technique shows a greater degree of healing and better biomechanical outcome. The suture anchor technique uses “all-inside" fixation and avoids the need for a distal fixation which potentially places abrasive forces on the sutures used. The trans-tibial pullout repair can restore the attachment and contact pressure near normal value, also the tunnel drilling stimulating growth factors and progenitor cells from bone marrow and facilitate the ability of meniscus to convert axial load into hoop stress. The concern of trans-tibial pullout repair is its ‘bungee effect’ and repetitive loading resulted in the displacement of this repair complex and might compromise healing because of decreased stiffness and micromotion of the meniscus-suture complex.

Quantitative and Qualitative Assessment of the Posterior Medial Meniscus Anatomy: Defining Meniscal Ramp Lesions

Background: Meniscal ramp lesions have been defined as a tear of the peripheral attachment of the posterior horn of the medial meniscus (PHMM) at the meniscocapsular junction or an injury to the meniscotibial attachment. Precise anatomic descriptions of these structures are limited in the current literature. Purpose: To quantitatively and qualitatively describe the PHMM and posteromedial capsule anatomy pertaining to the location of a meniscal ramp lesion with reference to surgically relevant landmarks. Study Design: Descriptive laboratory study. Methods: Fourteen male nonpaired fresh-frozen cadavers were used. The locations of the posteromedial meniscocapsular and meniscotibial attachments were identified. Measurements to surgically relevant landmarks were performed with a coordinate measuring system. To further analyze the posteromedial meniscocapsular and meniscotibial attachments, hematoxylin and eosin and alcian blue staining were conducted on a separate sample of 10 nonpaired specimens. Results: The posterior meniscocapsular attachment had a mean ± SD length of 20.2 ± 6.0 mm and attached posteroinferiorly to the PHMM at a mean depth of 36.4% of the total posterior meniscal height. The posterior meniscotibial ligament attached on the PHMM 16.5 mm posterior and 7.7 mm medial to the center of the posterior medial meniscal root attachment. The meniscotibial ligament tibial attachment was 5.9 ± 1.3 mm inferior to the articular cartilage margin of the posterior medial tibial plateau. The posterior meniscocapsular attachment converged with the meniscotibial ligament at the most posterior point of the meniscocapsular junction in all specimens. Histological staining of the meniscocapsular and meniscotibial ligament PHMM attachments showed similar structure, cell density, and fiber directionality, with no qualitative difference in the makeup of their collagen matrices across all specimens. Conclusion: The anatomy of the area where a medial meniscal ramp tear occurs revealed that the 2 posterior meniscal attachments merged at a common attachment on the PHMM. Histological analysis validated a shared attachment point of the meniscocapsular and meniscotibial attachments of the PHMM. Clinical Relevance: The findings of this study provide the anatomic foundation for an improved understanding of the meniscocapsular and meniscotibial attachments of the PHMM, which may help provide a more precise definition of a meniscal ramp lesion.

The Lateral Meniscus Posterior Root and Meniscofemoral Ligaments are Stabilizing Structures in the ACL Deficient Knee: A Biomechanical Study

The lateral meniscus posterior root was a significant primary stabilizer of the knee for internal rotation and anterior tibial translation during pivoting activities at lower flexion angles and internal rotation at higher flexion angles. The menisci have an important role in stabilizing the knee joint. The biomechanical effects of lateral meniscal posterior root tears with versus without meniscofemoral ligament (MFL) tears in anterior cruciate ligament (ACL) deficient knees have not been studied in detail. To determine the biomechanical effects of the lateral meniscus (LM) posterior root tear in anterior cruciate (ACL) - intact and ACL-deficient knees. In addition, the biomechanical effects of disrupting the meniscofemoral ligaments (MFLs) in ACL deficient knees with meniscal root tears was evaluated. It was hypothesized that disruption of the posterior horn lateral meniscal root attachment would cause a significant increase in internal rotation during simulated pivot shift and internal rotation tests in the ACL-deficient knee, both with and without intact meniscofemoral ligaments. In addition, it was hypothesized that disruption of the LM root and MFLs would significantly increase internal rotation at high flexion angles. Controlled laboratory study. Ten paired (n = 20) fresh-frozen cadaveric knees were mounted in a 6 degree-of-freedom robot for testing and divided into two sequential cutting groups. The sectioning order for group 1 was (1) ACL, (2) LM posterior root, (3) MFLs, and for group 2 was (1) LM posterior root, (2) ACL, and (3) MFLs. For each cutting state, displacements and rotations of the tibia were measured and compared to the intact state following a simulated pivot shift test (5 Nm internal rotation torque combined with a 10 Nm valgus torque) at 0°, 20°, 30°, 60° and 90° of knee flexion; an anterior translation load (88 N) at 0°, 30°, 60° and 90° of knee flexion; and internal rotation (5-Nm) at 0°, 30°, 60°, 75° and 90° of knee flexion. Cutting the LM root and MFLs significantly increased ATT during a simulated pivot shift test at 20° and 30° when compared to the ACL cut state (both p<0.05). Cutting the LM root in ACL intact knees significantly increased internal rotation by between 0.7° ± 0.3° and 1.3° ± 0.9° (all p<0.05), except at 0° (p=0.136). When the ACL + LM root cut state was compared to the ACL cut state, the increase in internal rotation was significant at higher flexion angles of 75° and 90° (both p<0.05) but not between 0°- 60° (all p>0.2). For an anterior translation load, cutting the LM root in ACL deficient knees significantly increased ATT only at 30° (p=0.007). The LM posterior root was a significant stabilizer of the knee for anterior tibial translation during a simulated pivot shift test at lower flexion angles, and internal rotation at higher flexion angles. Increased knee instability due to lateral meniscal root deficiency may contribute to increased functional limitations in patients and potentially to increased loads on ACL reconstruction grafts.

The LM Posterior Root Stabilizes the ACL Deficient Knee

Objectives:The menisci have an important role in stabilizing the knee joint. The biomechanical effects of lateral meniscal posterior root tears with or without meniscofemoral ligament (MFL) tears in anterior cruciate ligament (ACL) deficient knees have not been studied in detail. The aim of this study was to determine the biomechanical effects of disruption of the lateral meniscus posterior root attachment in ACL-intact and ACL-deficient knees. It was hypothesized that disruption of the posterior horn lateral meniscal root attachment would cause a significant increase in both anterior tibial translation (ATT) and internal rotation during a simulated pivot shift and also in internal rotation tests in the ACL-deficient knee, both with and without intact meniscofemoral ligaments.Methods:Ten paired (n = 20) fresh-frozen cadaveric knees were mounted in a 6 degree-of-freedom robot for testing and divided into two sequential cutting groups. The sectioning order for group 1 was (1) ACL, (2) lateral meniscus posterior root and (3) MFL. The sectioning order for group 2 was (1) lateral meniscus posterior root, (2) ACL, and (3) MFL. For each cutting state, displacements and rotations of the tibia were measured and compared to the intact state following a simulated pivot shift test (5 Nm internal rotation torque combined with a 10 Nm valgus torque) at 0°, 20°, 30°, 60° and 90° of knee flexion; an anterior translation load (88 N) at 0°, 30°, 60° and 90° of knee flexion; and internal and external rotation (5-Nm) at 0°, 30°, 60°, 75° and 90° of knee flexion.Results:Cutting the LM root and MFLs significantly increased ATT during a simulated pivot shift test at 20° and 30° when compared to the ACL cut state (p<0.05) (Figure 1). Cutting the LM root in ACL intact knees significantly increased internal rotation by between 0.4° ± 0.4° and 1.3° ± 0.9° (p<0.05), except at 0° (p=0.136). When the ACL + LM root cut state was compared to the ACL cut state, the increase in internal rotation was significant (p<0.05) at higher flexion angles (75° and 90°) but not between 0°- 60°. For an anterior translation load, cutting the LM root in ACL deficient knees significantly increased ATT at 30° (p<0.05).Conclusion:The LM posterior root was a significant primary stabilizer of the knee for internal rotation and anterior tibial translation during pivoting activities at lower flexion angles and internal rotation at higher flexion angles. Lateral meniscal posterior root tears should be repaired concurrently with ACL reconstruction. Increased knee instability due to lateral meniscal root deficiency may contribute to increased functional limitations in patients and potentially to ACL reconstruction graft failure.

Simplified Arthroscopic Lateral Meniscal Root Repair Involving the Use of 2 Cinch-Loop Sutures

The meniscal root attachments are critical for meniscal function by securing the menisci in place and allowing optimal shock absorption in the knee. Successful meniscal root repair has been shown to restore the knee's tibiofemoral contact pressure to the same state as an intact meniscus. Although there have been multiple different repair techniques described, there is no report in the literature regarding the use of 2 simple cinch-loop sutures for a meniscal root repair. This article presents an arthroscopic lateral meniscal root repair technique involving the use of 2 simple cinch-loop configuration sutures and tibial suture anchor fixation.

Tibiofemoral Contact Mechanics with Horizontal Cleavage Tear and Resection of the Medial Meniscus in the Human Knee.

The meniscus is known to increase the contact area and decrease contact pressure in the tibiofemoral compartments of the knee. Radial tears of the meniscal root attachment along with partial resections of the torn meniscal tissue decrease the contact area and increase pressure; however, there is a lack of information on the effects of a horizontal cleavage tear (HCT) and partial leaf meniscectomy of such tears on tibiofemoral contact pressure and contact area. Twelve fresh-frozen human cadaveric knees were tested under 10 conditions: 5 serial conditions of posterior medial meniscectomy (intact meniscus, HCT, repaired HCT, inferior leaf resection, and resection of both inferior and superior leaves), each at 2 knee flexion angles (0° and 60°) under an 800-N axial load. Tekscan sensors (model 4000) were used to measure the contact pressure and contact area. HCT and HCT repair resulted in small changes in the contact area and an increase in contact pressure compared with the intact condition. Resection of the inferior leaf resulted in significantly decreased contact area (to a mean 82.3% of the intact condition at 0° of flexion and 81.8% at 60° of flexion; p < 0.05) and increased peak contact pressure (a mean 36.3% increase at 0° flexion and 43.2% increase at 60° flexion; p < 0.05) in the medial compartment. Further resection of the remaining superior leaf resulted in additional significant decreases in contact area (to a mean 60.1% of the intact condition at 0° of flexion and 49.7% at 60° of flexion; p < 0.05) and increases in peak contact pressure (a mean 79.2% increase at 0° of flexion and 74.9% increase at 60° of flexion; p < 0.05). Resection of meniscal tissue forming the inferior leaf of an HCT resulted in substantially decreased contact area and increased contact pressure. Additional resection of the superior leaf resulted in a further significant decrease in contact area and increase in contact pressure in the medial compartment. Repair or minimal resection of meniscal tissue of an HCT may be preferred to complete leaf resection to maintain knee tibiofemoral contact mechanics.

Posterior Root Meniscal Tears: Preoperative, Intraoperative, and Postoperative Imaging for Transtibial Pullout Repair.

The menisci play an important biomechanical role in axial load distribution of the knees by means of hoop strength, which is contingent on intact circumferentially oriented collagen fibers and meniscal root attachments. Disruption of the meniscal root attachments leads to altered biomechanics, resulting in progressive cartilage loss, osteoarthritis, and subchondral edema, with the potential for development of a subchondral insufficiency fracture. Identification of meniscal root tears at magnetic resonance (MR) imaging is crucial because new arthroscopic surgical techniques (transtibial pullout repair) have been developed to repair meniscal root tears and preserve the tibiofemoral cartilage of the knee. An MR imaging classification of posterior medial meniscal root ligament lesions has been recently described that is dedicated to the posterior root of the medial meniscus. An arthroscopic classification of meniscal root tears has been described that can be applied to the anterior and posterior roots of both the medial meniscus and the lateral meniscus. This arthroscopic classification includes type 1, partial stable root tears; type 2, complete radial root tears; type 3, vertical longitudinal bucket-handle tears; type 4, complex oblique tears; and type 5, bone avulsion fractures of the root attachments. Knowledge of these classifications and the potential contraindications to meniscal root repair can aid the radiologist in the preoperative reporting of meniscal root tear types and the evaluation of the tibiofemoral cartilage. As more patients undergo arthroscopic repair of meniscal root tears, familiarity with the surgical technique and the postoperative radiographic and MR imaging appearance is important to adequately report the imaging findings. ©RSNA, 2016.

Meniscal Root Repairs.

Meniscal root tears are substantial injuries that usually require surgical management. If left untreated, meniscal root tears can lead to the rapid onset of osteoarthritis similar to that seen after a total meniscectomy. Meniscal root tears often go unnoticed on magnetic resonance imaging and arthroscopy, in large part because meniscal root anatomy and its biomechanical importance have been defined only recently. In a transtibial meniscal root repair, the current clinical standard of care, the root is reattached to its native attachment site on the tibial plateau, restoring tibiofemoral contact mechanics. While this video article shows a posterior medial root repair technique, the same anatomic, biomechanical, and surgical principles apply to a posterior lateral meniscal root attachment. The principal steps in this procedure include (1) verifying the presence of a posterior medial meniscal root tear with arthroscopic visualization and probing, (2) inspecting the root tear and debriding the root attachment site to bone with a curet, (3) arthroscopic release of any adhesions that cause retraction of the meniscal root to a nonanatomic position, (4) drilling of two separate transtibial tunnels that extend down to the anteromedial portion of the tibia, (5) placing an accessory portal to pass the sutures, (6) placing two simple sutures through the torn meniscal root and shuttling them down the tibial tunnels, and (7) tying the sutures over a surgical button on the anteroproximal portion of the tibia with the knee flexed 90°. Postoperatively, patients remain non-weight-bearing for six weeks. Passive knee flexion from 0° to 90° is allowed for the first two weeks. After two weeks, motion is increased as tolerated. Patients initiate weight-bearing at postoperative week six and commence the use of a stationary bicycle. Resistive exercises are slowly progressed, and the patient should avoid squatting as well as squatting and lifting for four months. Patients are expected to return to normal physical activity within four to six months postoperatively.

Recent Advances in Posterior Meniscal Root Repair Techniques

Posterior root avulsions of the medial and lateral menisci result in decreased areas of tibiofemoral contact and increased tibiofemoral contact pressures. These avulsions may lead to the development of osteoarthritis. Therefore, two surgical techniques, the transtibial pullout repair and the suture anchor repair, have recently been developed to restore the native structure and function of the meniscal root attachment. Compared with the historical alternative of partial or total meniscectomy, these techniques allow for meniscal preservation and anatomic reduction of the meniscal roots, with the goal of preventing the development and progression of osteoarthritis. However, early biomechanical and clinical studies have reported conflicting results on the effectiveness of both techniques with regard to resisting displacement and facilitating healing. Although there is currently a lack of consensus on which is the superior technique, transtibial pullout and suture anchor repairs are increasingly used in clinical practice.

Consequences of Tibial Tunnel Reaming on the Meniscal Roots During Cruciate Ligament Reconstruction in a Cadaveric Model, Part 1

Background: The current standard for treating complete tears of the anterior cruciate ligament (ACL) is reconstruction, which requires reaming a tibial tunnel. Based on recent anatomic and biomechanical studies, this reconstruction tunnel may cause injuries to the anterior meniscal root attachments. Purpose/Hypothesis: The purpose was to determine if injuries occurred to the anteromedial (AM) and anterolateral (AL) meniscal root attachments because of reaming a tibial reconstruction tunnel in the anatomic center of the ACL footprint. It was hypothesized that tibial tunnel reaming for ACL reconstruction would result in significant decreases in the attachment area and in ultimate failure strength for the AL root. Study Design: Controlled laboratory study. Methods: Twelve matched pairs of human cadaveric knees were tested. One knee from each pair remained intact, while the contralateral knee was reamed with a tibial tunnel for an anatomic ACL reconstruction. The attachment areas of the anterior meniscal roots were measured with a coordinate measuring device before and after tunnel reaming. The anterior meniscal roots were then pulled to failure with a dynamic tensile testing machine. Results: There was a significant mean decrease in the attachment area for the AL root (%Δ, 38%; 95% CI, 25-51) after ACL tunnel reaming compared with the intact state (P = .003). The mean ultimate failure strength of the native AL root (mean, 610 N; 95% CI, 470-751) was significantly stronger (P = .015) than that of the AL root with a reamed ACL reconstruction tunnel (mean, 506 N; 95% CI, 353-659). Tunnel reaming did not significantly affect the AM root attachment area or ultimate failure strength. Conclusion: Tibial tunnel reaming during anatomic single-bundle ACL reconstruction significantly decreased the AL meniscal root attachment area and ultimate failure strength. The AM root was not significantly affected by reaming of the ACL reconstruction tunnel. Future studies should investigate the clinical importance of these iatrogenic injuries to the AL root. Clinical Relevance: The ACL reconstruction tunnels reamed in the center of the ACL tibial footprint caused a significant decrease in the attachment area and ultimate strength of the AL meniscal root attachment. Clinically, repositioning guide pins placed in the lateral aspect of the ACL attachment before tibial tunnel reaming may minimize iatrogenic injuries to the AL meniscal root attachment.