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.

Younger patients, lower BMI, complete meniscus root healing, lower HKA degree and shorter preoperative symptom duration were the independent risk factors correlated with the good correction of MME in patients with repaired MMPRTs.

PURPOSE: To evaluate the clinical and radiological outcomes of arthroscopically assisted tendon graft anatomic reinforced reconstruction of the medial meniscus posterior root tears (MMPRTs) and identify relevant factors affecting the correction of medial meniscal extrusion (MME). METHODS: Fifty-three MMPRTs patients who underwent arthroscopically assisted tendon graft reconstruction of the meniscal root between 2018 and 2020 were evaluated retrospectively. the patients were divided into 2 groups according to the correction of MME (maintained MME group: 32 cases vs. increased MME group: 21 cases). The clinical and radiological outcomes of arthroscopically assisted tendon graft reconstruction of the meniscal root, including postoperative correction of MME and functional recovery of the knee were assessed in this study, and potential independent risk factors that could influence the correction of MME were also evaluated. RESULTS: The functional recovery of the knee was significantly improved at the end of follow-up (P < 0.001; respectively), furthermore, a comparison of the final functional outcomes between the groups showed that the mean Lysholm score and IKDC score of the maintained MME group were significantly improved than those of increased MME group. 60.4% had good correction of MME, and patients with complete healing had better extrusion correction than those with partial healing and non-healing. Binary logistic regression models analysis indicated that the age (OR = 1.053, P = 0.048), BMI (OR = 1.376, P = 0.004), meniscus root healing status (OR = 7.701, P = 0.005), HKA degree (OR = 1.891, P = 0.011) and preoperative symptom duration (OR = 1.055, P = 0.013) were the independent risk factors correlated with correction of MME. Additionally, the ROC curve demonstrated the cut-off values of the Age, BMI, HKA degree and preoperative symptom duration were 46.0 years, 22.5 kg/m2, 3.2° and 9.5 months, respectively, CONCLUSIONS: The arthroscopically assisted tendon graft anatomic reinforced reconstruction of the meniscal root showed clinical improvement and prevented the progression of postoperative MME. Additionally, younger patients, lower BMI, complete meniscus root healing, lower HKA degree and shorter preoperative symptom duration were the independent risk factors correlated with the good correction of MME in patients with repaired MMPRTs. LEVEL OF EVIDENCE: Level IV.

Concomitant posterior anchoring further reduces posterior meniscal extrusion during pullout repair of medial meniscus posterior root tears: a retrospective study.

PURPOSE: Transtibial pullout repair improves the clinical outcomes of medial meniscus (MM) posterior root tears (PRTs); however, reducing MM extrusion remains challenging. Thus, the purpose of this study was to examine the role of additional posterior anchoring (PA) during pullout repair in reducing the severity of MM extrusion compared to pullout repair alone. METHODS: Patients who underwent pullout repair with two-cinch stitches (TCS) only or TCS combined with PA (TCS-PA)-deployment of an additional suture anchor in the posteromedial corner of MM-were included retrospectively. MM medial and posterior extrusion (MMME and MMPE), MM extrusion and remaining volume (MMEV and MMRV), and corresponding ratios were evaluated pre-operatively and three months post-operatively using a three-dimensional meniscal model at 10° and 90° of knee flexion and compared within and between groups. RESULTS: A total of 15 and 16 patients treated with TCS and TCS-PA, respectively, were enrolled. At 90° knee flexion, both techniques significantly reduced MMPE (TCS: 4.2 ± 0.7 mm to 3.5 ± 0.6 mm, p < 0.05; TCS-PA: 3.7 ± 0.8 mm to 2.8 ± 0.7 mm, p < 0.05) at three months post-operatively. TCS-PA reduced MMPE more significantly than TCS alone (p < 0.05). Only TCS-PA significantly improved the MMEV and MMRV ratios (39.6 ± 8.9% to 28.1 ± 6.0%, p < 0.05 and 60.4 ± 8.9% to 71.9 ± 6.0%, p < 0.05, respectively). Significance was not found in all other comparisons. CONCLUSIONS: Both techniques improved MMPE at knee flexion at the three month follow-up, with TCS-PA providing significantly superior results. Our findings support the evidence that the application of PA may be an effective surgical option for alleviating persistent MMPE.

Medial meniscus posterior root tear reconstructed with gracilis autograft improve healing rate and patient reported outcome measures.

BACKGROUND: Many surgeries have not reversed or prevented progressive symptomatic knee arthritis, and there is no consensus regarding the ideal repair or reconstruction technique for meniscal root treatment. Additionally, there is a lack of studies comparing the clinical efficacy evaluation of different repair techniques. The aim of the present study is to compare the clinical efficacy and healing rates of meniscus root in the treatment of medial meniscus posterior root tear (MMPRT) with the arthroscopically assisted meniscus root reconstruction with gracilis autograft and transtibial pull-out technique. METHODS: Patients with MMPRT (type II) who received treatment of posterior meniscus root attachment point through the tibial tunnel between January 2018 and April 2019 were included in this study. Patients were divided into 2 groups (arthroscopically assisted gracilis autograft reconstruction technique: 29 cases; transtibial pull-out technique group: 35 cases) according to the different treatment methods. The mean follow-up period was 26.9 ± 2.3 months. The demographics, functional recovery of the knee, and meniscus root healing rates (assessed using knee magnetic resonance imaging (MRI) at the final follow-up) were compared between the two groups. RESULTS: There was a statistically significant improvement in the Lysholm score, international knee documentation committee (IKDC) score, and visual analogue scale (VAS) score (P < 0.001 in both groups). Additionally, compared with the transtibial pull-out repair group, the arthroscopically assisted reconstruction with gracilis autograft showed significant improvement in the meniscus root healing rates, Lysholm score, and IKDC score at the end of follow-up (P < 0.05). CONCLUSIONS: Compared with the transtibial pull-out technique, the arthroscopically assisted meniscus root reconstruction with gracilis autograft was advantageous for treating these patients with superior clinical outcome and higher meniscus root healing rates. LEVEL OF EVIDENCE: Level III.

Evidence-based rationale for treatment of meniscal lesions in athletes.

Meniscal injuries in elite athletes are a common cause of missed game time and even have the potential to be career shortening. In this patient group, care must be paid not only to the pathology, but also to a player's contract status, time in the season, specific demands of his/her sport and position on the field, and future consequences. Successful treatment requires the clinician to understand the player's goals and needs, communicate effectively between all stakeholders, and a have knowledge of the challenges posed by the different types of meniscal tear seen in this population. Paramount is the distinction between injuries to the medial and lateral meniscus. Deficiency of the lateral meniscus, as a result of a tear or a meniscectomy, leads to frequent early problems and inexorably to chondral degeneration thereby affecting an athlete's ability to perform. Therefore, it is strongly recommended to repair the majority of lateral meniscal tears. Medial meniscal tears pose a more challenging treatment dilemma, as the success of partial meniscectomy in achieving reproducible, early return to play must be balanced against the long-term degenerative consequences. Many meniscal tears are correctly treated non-operatively.Level of evidence V.

Magnetic resonance imaging of the meniscal roots.

The meniscal roots and supporting structures anchor the menisci to the tibial plateau and resist hoop stress, thereby preventing radial displacement of the menisci and secondary degenerative tibiofemoral compartment changes that may occur if this is compromised. The anatomy of the four meniscal roots and their supporting structures on magnetic resonance imaging (MRI) will be outlined in this review article, as well as the imaging appearances of meniscal root-related pathology, namely meniscal root degeneration and tears, meniscal extrusion and tibial plateau cystic lesions.

Meniscal root tears occur frequently in multi-ligament knee injury and can be predicted by associated MRI injury patterns.

PURPOSE: The frequency of meniscal root tears in association with multi-ligament knee injury has not been established but adds to the complexity of surgical reconstruction and may have long-term consequences. Therefore, identifying root tears, on preoperative imaging, is important. The aim of this study was to identify the frequency of meniscal root tears, on preoperative magnetic resonance imaging, following multi-ligament injury and distinguish associated injury patterns that may aid detection. METHODS: Cases were identified from a prospectively collected institutional database. The magnetic resonance imaging of 188 multi-ligament injuries [median age 31 years (range 16-64)] was retrospectively reviewed by three musculoskeletal radiologists with the presence of meniscal injuries recorded alongside the ligament injury pattern and intra-articular fractures. Assessment of injury pattern was solely made on this imaging. RESULTS: 38 meniscal root injuries were identified in 37 knees (overall frequency = 20.2%; medial = 10.6%; lateral = 9.6%). The frequency of meniscal root tears was not increased in higher grade injuries (21.5% vs. 17.0%, n.s.). Valgus injury patterns were associated with lateral root tears (p < 0.05) and varus patterns were associated with medial root tears (p < 0.05). Further, fractures in the same compartment were associated with both medial and lateral root tears (p < 0.05). CONCLUSIONS: Meniscal root tears occur more frequently in multi-ligament knee injury than previously reported with isolated anterior cruciate rupture. Root tears can be predicted by ligament injury patterns and fractures sustained (suggestive of a compressive force). In multi-ligament cases, the preoperative magnetic resonance imaging can be used to detect these tears and associated patterns of injury. LEVEL OF EVIDENCE: IV.

The role of suture cutout in the failure of meniscal root repair during the early post-operative period: a biomechanical study.

PURPOSE: To assess the role of suture cutout in the mechanics of failure of the repaired posterior meniscal root during the early post-operative period when using sutures of different shape. METHODS: Twenty medial porcine menisci were randomized in two groups depending on the suture shape used to repair the posterior root: thread or tape. The sutured menisci were subjected to cyclic loading (1000 cycles, (10, 30) N) followed by load-to-failure testing. Residual displacements, stiffness, and ultimate failure load were determined. During tests, the tissue-suture interface was recorded using a high-resolution camera. RESULTS: In cyclic tests, cutout progression at the suture insertion points was not observed for any specimen of either group and no differences in residual displacements were found between use of thread or tape. In load-to-failure tests, suture cutout started in all menisci at a load close to the ultimate failure and all specimens failed by suture pullout. Suture tape had a greater ultimate load with no other differences. CONCLUSIONS: In a porcine model of a repaired posterior meniscal root subjected to cyclic loads representative of current rehabilitation protocols in the early post-operative period under restricted loading conditions, suture cutout was not found as a main source of permanent root displacement when using suture thread or tape. Suture cutout progression started at high loading levels close to the ultimate load of the construct. Tape, with a meniscus-suture contact area larger than thread, produced higher ultimate load.

Complete posterolateral meniscal root tear is associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament injuries.

PURPOSE: The purpose of this study was to investigate whether the complete posterolateral meniscal root tear (PLMRT) would be associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament (ACL) injuries. METHODS: From 2013 to 2015, a total of 1095 consecutive patients were diagnosed as having noncontact ACL injuries and underwent primary ACL reconstructions. Among them, 140 patients were arthroscopically verified to have concomitant PLMRTs. Application of the exclusion criteria finally left 74 patients who were finally allocated into high-grade pivot-shift (grades II and III) group (n = 51) and low-grade pivot-shift (grades 0 and I) group (n = 23) according to the results of pre-operative pivot-shift tests performed under anesthesia. Predictors of high-grade pivot-shift phenomenon, including degree of PLMRTs, integrity of posterior MFLs, status of lateral meniscal extrusion, age, sex, body mass index (BMI), and KT-1000 arthrometer side-to-side difference (SSD), were assessed by multivariable logistic regression analysis. RESULTS: The proportion of patients with complete PLMRT in high-grade pivot-shift group was significantly larger than that in low-grade pivot-shift group. In addition, complete PLMRT was significantly [odds ratio (OR) 4.044; 95% CI 1.125-14.534; P = 0.032] associated with high-grade pivot-shift phenomenon in noncontact ACL injury, especially for those with a time from injury to surgery of ≥12 weeks (OR 16.593; 95% CI 1.073-56.695; P = 0.014). However, no significant association was identified between neither the integrity of posterior MFLs nor the status of lateral meniscal extrusion and the high-grade pivot-shift phenomenon. CONCLUSION: Complete PLMRT is identified to be an independent risk factor of high-grade pivot-shift phenomenon in noncontact ACL injuries, particularly for those with a time from injury to surgery of ≥12 weeks. LEVEL OF EVIDENCE: IV.

Influence of lateral meniscal posterior root avulsions and the meniscofemoral ligaments on tibiofemoral contact mechanics.

PURPOSE: The purpose of this study was to investigate the effect of lateral meniscal posterior root avulsions combined with intact meniscofemoral ligaments (MFLs), deficient MFLs, anterior cruciate ligament (ACL) tears and reconstructions, and root repairs using an established tibiofemoral contact mechanics testing protocol. METHODS: Ten fresh-frozen cadaveric knees were tested with six knee conditions (1: intact; 2: lateral meniscal posterior root avulsion; 3: root avulsion and deficient MFLs; 4: condition 3 with ACL tear; 5: condition 4 with ACL reconstruction; 6: ACL reconstruction with root repair) at five flexion angles (0°, 30°, 45°, 60°, and 90°), under a 1000-N axial load. Contact area and pressure were measured with Tekscan sensors. RESULTS: Compared to the intact state, condition 2 did not significantly change lateral compartment contact area or pressure. Changes in contact mechanics were greater at increased flexion angles; for condition 3 at 0° and 90°, contact area decreased 37 and 52 % [95 % CI (21-53) and (39-66), respectively] and mean contact pressure increased 55 and 87 % [95 % CI (33-76) and (59-114), respectively]. Root repair with ACL reconstruction was not significantly different from the intact state. CONCLUSIONS: The MFLs protect the lateral compartment from changes in contact mechanics in the setting of a lateral meniscal posterior root avulsion, whereas a combination of lateral meniscal root avulsion and deficient MFLs leads to significant changes. Concurrent ACL reconstruction and lateral meniscal root repair restore mean contact pressure and area to the intact state and are recommended in this combined injury to prevent or slow the development of lateral compartment arthritis.

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.

Developing an experimental model of early knee osteoarthritis after medial meniscus posterior root release: an in vivo study.

PURPOSE: To develop a predictable and reproducible model of knee osteoarthritis after medial meniscus posterior root release. METHODS: Posteromedial meniscal root tears were created in 12 White New Zealand rabbit knees. The contralateral limbs were used as healthy controls. The animals were euthanized at 16 weeks postoperatively; tissue samples of femoral and tibial articular cartilage were collected and processed for macro and microscopic analyses to detect signs of early degeneration. Clinical evaluation of the weight-bearing status on the affected knee was conducted at 0-, 4-, 8-, and 16-weeks postoperatively. RESULTS: Early and severe osteoarthritic changes were the hallmark and the main findings after 16-weeks post-surgery. Macroscopically, extensive osteoarthritic changes were observed across the femoral condyle and tibial plateau. Microscopic finding included ulcerations, fissures, fibrillations, pitting, and loss of the superficial layer. Cellularity was diminished, the normal pattern of distribution in columns was lost, and subchondral bone exposure was also evident. CONCLUSIONS: This study describes a novel model of knee osteoarthritis that may guide the development of tailored interventions to delay or prevent knee osteoarthritis. This knowledge could shift the current treatment paradigm toward more conservative and knee salvageable treatment options and increase surgeons' awareness of this injury pattern. Such considerations may have a positive impact on clinical decision-making and subsequent patient-reported clinical outcomes. DESIGN: Controlled laboratory study. LEVEL OF EVIDENCE: II.

Subchondral insufficiency fracture of the knee: review of current concepts and radiological differential diagnoses.

Subchondral insufficiency fracture of the knee (SIFK) is a common cause of knee joint pain in older adults. SIFK is a type of stress fracture that occurs when repetitive and excessive stress is applied to the subchondral bone. If the fracture does not heal, the lesion develops into osteonecrosis and results in osteochondral collapse, requiring surgical management. Because of these clinical features, SIFK was initially termed "spontaneous osteonecrosis of the knee (SONK)" in the pre-MRI era. SONK is now categorized as an advanced SIFK lesion in the spectrum of this disease, and some authors believe the term "SONK" is a misnomer. MRI plays a significant role in the early diagnosis of SIFK. A subchondral T2 hypointense line of the affected condyle with extended bone marrow edema-like signal intensity are characteristic findings on MRI. The large lesion size and the presence of osteochondral collapse on imaging are associated with an increased risk of osteoarthritis. However, bone marrow edema-like signal intensity and osteochondral collapse alone are not specific to SIFK, and other osteochondral lesions, including avascular necrosis, osteochondral dissecans, and osteoarthritis should be considered. Chondral lesions and meniscal abnormalities, including posterior root tears, are also found in many patients with SIFK, and they are considered to be related to the development of SIFK. We review the clinical and imaging findings, including the anatomy and terminology history of SIFK, as well as its differential diagnoses. Radiologists should be familiar with these imaging features and clinical presentations for appropriate management.

Current concepts on meniscal repairs.

The specific meniscus injury pattern were divided into many patterns. Nowadays, the meniscus root injury, radial tear meniscus, bucket handle tear meniscus and Ramp lesion were particularly focused on many way to manage and still controversial a lot of issues. Meniscus root tears (MRTs) and Ramp lesion are the most ignored, or misdiagnosed causes of chronic knee pain. Most patients delayed seeking treatment, consequently resulting in cartilage loss, and leading to the condition progressing to osteoarthritis knee. This has resulted in the rate of MR and Ramp repair increase significantly. The bucket handle meniscus tear trend to strong saving the anatomical meniscus and avoid to menisectomy. This article, on the other hand, will reveal you how to save and secure a nearly native meniscus fixation. In case of the radial meniscus, the partial meniscectomy is still used to treat this type of injury today, but it does not prevent degenerative changes from occurring, which can lead to unfavorable outcomes. Meniscal repair is a popular procedure for treating radial tears as an alternative to surgery. However, this pattern of meniscus tear can be difficult to repair and has a high failure rate, the arthroscopic meniscus repair techniques are published.

Meniscal Repair Techniques.

The menisci play a vital role in knee joint stability, load distribution, and lubrication, protecting the joint surfaces from degenerative change. Meniscal repair protects the joint from increased loading and when successful reduces progression of osteoarthritis. Successful repair involves accurate surgical techniques, guarded postoperative rehabilitation, and potential use of additional biologics to promote healing. An integrated approach to meniscal surgery is required as part of an overall strategy to preserve and restore knee function, preserving meniscal tissue whenever possible. This article reviews the repair techniques: procedures, indications, and rehabilitation for meniscal repair.

A novel surgical technique for arthroscopic repair of type II posterior lateral meniscal root tear.

BACKGROUND: Several suture repair techniques have been reported for radial tear close to the posterior lateral meniscal root (type II PLMRT). However, no study has evaluated the clinical results after repair using the FasT-Fix system. This paper describes a novel H-plasty surgical repair technique and reports its clinical results. METHODS: From January 2015 to January 2017, 47 patients underwent repair of type II PLMRT with concomitant anterior cruciate ligament reconstruction and were included in this study. Assessments performed preoperatively and at final follow-up included the Lysholm score, subjective International Knee Documentation Committee (IKDC) score, and knee stability assessments (pivot-shift test, Lachman test, KNEELAX arthrometer side-to-side difference). Magnetic resonance imaging was used to compare the lateral meniscal extrusion pre- versus postoperatively. Second-look arthroscopy was performed to evaluate the meniscal healing in 38 cases. RESULTS: Forty-seven patients were followed up for an average of 30.7 months (range 18-46 months). No patients experienced meniscal mechanical symptoms. At final follow-up, there were significant improvements in the Lysholm score, IKDC score, knee stability assessments, and lateral meniscal extrusion compared with the preoperative values. In the 38 of 47 patients that underwent second-look arthroscopy after an average of 17.5 months (range 14-19 months), all repairs (100%) were completely healed. CONCLUSIONS: The novel H-plasty repair using the FasT-Fix system was an effective surgical treatment for type II PLMRT. Considering the satisfactory clinical results and the convenience of the surgery, H-plasty repair is recommended to be used preferentially.

Utilization of Transtibial Centralization Suture Best Minimizes Extrusion and Restores Tibiofemoral Contact Mechanics for Anatomic Medial Meniscal Root Repairs in a Cadaveric Model.

BACKGROUND: Although posterior medial meniscal root (PMMR) repairs are often successful, postoperative meniscal extrusion after a root repair has been identified as a potential clinical problem. PURPOSE/HYPOTHESIS: The purpose was to quantitatively evaluate the tibiofemoral contact mechanics and extent of meniscal extrusion after a PMMR repair. It was hypothesized that the addition of a centralization suture (into the posterior medial tibial plateau) would help restore normal joint load-bearing characteristics and restore the native amount of meniscal extrusion after a root tear. Furthermore, we hypothesized that the amount of meniscal extrusion would be greatest in loaded and flexed knees when measured at the posterior border of the medial collateral ligament (MCL). STUDY DESIGN: Controlled laboratory study. METHODS: Meniscal extrusion and tibiofemoral contact mechanics were measured using 3-dimensional digitization and pressure sensors in 10 nonpaired, human cadaveric knees. The PMMR of each knee was tested under 6 states: (1) intact; (2) type 2A PMMR tear; (3) anatomic transtibial pull-out root repair; (4) anatomic transtibial pull-out repair with centralization; (5) nonanatomic transtibial pull-out repair; and (6) nonanatomic transtibial pull-out repair with centralization, with randomization of the order of conditions 3 and 4, and 5 and 6. The testing protocol loaded knees with a 1000-N axial compressive force at 4 flexion angles (0°, 30°, 60°, 90°) in each state. Meniscal extrusion was measured with a 3-dimensional coordinate digitizer at 0° and 90° in both the loaded and unloaded states and calculated from the difference from the articular margin of the tibia to the periphery of the meniscus. Peak contact pressure, contact area, and total contact pressure were also recorded for all states at all flexion angles. Statistical analysis investigated the independent effects of flexion, state, and loading using 3 distinct 2-factor models. RESULTS: Differences in the contact mechanics between repair techniques were most notable at higher flexion angles, demonstrating significantly higher average and peak contact pressures for nonanatomic repair states when compared with anatomic repairs with and without centralization (all P < .05). In unloaded knees at full extension, the magnitude of medial meniscal extrusion was significantly higher at the posterior border of the MCL compared with the posterior medial tibia ( P < .001) and adjacent to the root attachment on the tibia locations ( P < .001). Both anatomic repair states had no significant difference in the degree of extrusion when compared with the intact state. CONCLUSION: The anatomic transtibial pull-out root repair and the anatomic transtibial pull-out root repair with centralization techniques best restored contact mechanics of the knee and meniscal extrusion when compared with root tear and nonanatomic repair states at time zero. There were no significant differences in contact pressure or magnitude of extrusion between the anatomic repair state and the anatomic repair with centralization state. We found that extrusion is best measured in the coronal plane at the posterior border of the MCL for unloaded knees. However, the degree of extrusion increased as the knee was loaded and flexed to 90°. CLINICAL RELEVANCE: When there are concerns about meniscal extrusion with a medial meniscal root repair, the addition of a centralization suture may be beneficial for patients in reducing pathologic meniscal extrusion and restoring joint contact mechanics.

Different Suture Materials for Arthroscopic Transtibial Pull-out Repair of Medial Meniscal Posterior Root Tears: A Human Biomechanical Study.

BACKGROUND: Transtibial pull-out repair of the medial meniscal posterior root (MMPR) has been largely assessed through biomechanical studies. Biomechanically comparing different suture types would further optimize MMPR fixation and affect clinical care. PURPOSE/HYPOTHESIS: The purpose of this study was to determine the optimal suture material for MMPR fixation. It was hypothesized that ultra high-molecular weight polyethylene (UHMWPE) suture tape would be biomechanically superior to UHMWPE suture and standard suture. STUDY DESIGN: Controlled laboratory study. METHODS: The MMPR attachment was divided in 24 human cadaveric knees and randomly assigned to 3 repair groups: UHMWPE suture tape, UHMWPE suture, and standard suture. Specimens were dissected down to the medial meniscus, and the posterior root attachments were sectioned off the tibia. Two-tunnel transtibial pull-out repair with 2 sutures, as determined by the testing group, was performed. The repair constructs were cyclically loaded between 10 and 30 N at 0.5 Hz for 1000 cycles to mimic the forces experienced on the medial meniscus during postoperative rehabilitation. Displacement was recorded at 1, 50, 100, 500, and 1000 cycles. Ultimate failure load, displacement at failure, and load at 3 mm of displacement (clinical failure) were also recorded. RESULTS: UHMWPE suture tape had significantly less displacement of the medial meniscus when compared with standard suture at 1 (-0.22 mm [95% CI, -0.41 to -0.02]; P = .025) and 50 (-0.35 mm [95% CI, -0.67 to -0.03]; P = .029) cycles. There were no other significant differences observed in displacement between groups at any number of cycles. UHMWPE suture tape had significantly less displacement at the time of failure than standard suture (-3.71 mm [95% CI, -7.17 to -0.24]; P = .034). UHMWPE suture tape had a significantly higher load to reach the clinical failure displacement of 3 mm than UHMWPE suture (15.64 N [95% CI, 0.02 to 31.26]; P = .05). There were no significant differences in ultimate failure load between groups. CONCLUSION: The meniscal root repair construct with UHMWPE suture tape may be stronger and less prone to displacement than that with standard suture or UHMWPE suture. CLINICAL RELEVANCE: UHMWPE suture tape may provide better clinical results compared with UHMWPE suture and standard suture.

Early Osteoarthritis After Untreated Anterior Meniscal Root Tears: An In Vivo Animal Study.

BACKGROUND: Meniscal root tears cause menisci and their insertions to inadequately distribute loads and potentially leave underlying articular cartilage unprotected. Untreated meniscal root tears are becoming increasingly recognized to induce joint degradation; however, little information is known about anterior meniscal root tears and how they affect joint tissue. PURPOSE: To observe the early degenerative changes within the synovial fluid, menisci, tibial articular cartilage, and subchondral bone after arthroscopic creation of untreated anterior meniscal root tears. STUDY DESIGN: Controlled laboratory study. METHODS: Anterolateral meniscal root tears were created in 1 knee joint of 5 adult Flemish Giant rabbits, and anteromedial meniscal root tears were created in 4 additional rabbits. The contralateral limbs were used as nonoperated controls. The animals were euthanized at 8 weeks postoperatively; synovial fluid was aspirated, and tissue samples of menisci and tibial articular cartilage were collected and processed for multiple analyses to detect signs of early degeneration. RESULTS: Significant changes were found within the synovial fluid, meniscal tissue, and tibial subchondral bone of the knees with anterior meniscal root tears when compared with controls. There were no significant changes identified in the tibial articular cartilage when comparing the tear groups with controls. CONCLUSION: This study demonstrated early degenerative changes within the synovial fluid, menisci, and tibial subchondral bone when leaving anterior meniscal root tears untreated for 8 weeks. The results suggest that meniscal tissue presents measurable, degenerative changes prior to changes within the articular cartilage after anterior meniscal root tears. Anterior destabilization of the meniscus arthroscopically may lead to measurable degenerative changes and be useful for future in vivo natural history and animal repair studies. CLINICAL RELEVANCE: The present study is the first to investigate various tissue changes after anterior meniscal root tears of both the medial and lateral menisci. The results from this study suggest that degenerative changes occur within the synovial fluid, meniscus, and tibial subchondral bone prior to any measurable changes to the tibial articular cartilage. Further studies should expand on this study to evaluate how these components continue to progress when left untreated for long periods.

Rehabilitation Following Meniscal Root Repair: A Clinical Commentary.

SYNOPSIS: There is a growing body of evidence surrounding the pathology and treatment of meniscal root tears. As surgical techniques are being developed and refined, rehabilitation protocols for meniscal root repairs must be defined and tested. Little information has been published regarding specific rehabilitation parameters for meniscal root repairs through all phases of rehabilitation. The goal of this commentary is to describe a rehabilitation program for meniscal root repairs that is founded on anatomical, physiological, and biomechanical principles with criteria-based progressions.