Meniscal repair: The current state and recent advances in augmentation

Injectable decellularized Wharton's jelly hydrogel containing CD56+ umbilical cord mesenchymal stem cell-derived exosomes for meniscus tear healing and cartilage protection

Traditional meniscectomy or suture for meniscal tear usually leads to failed self-healing, cartilage degeneration and worse osteoarthritis. The strategies that facilitate the healing process of torn meniscus and safeguard knee cartilage against degeneration will be promising for clinical therapy. The CD56+ umbilical cord mesenchymal stem cells (UCSCs) (CD56+UCSCs) were sorted from Wharton's jelly using flow cytometer. Then, the modified decellularized Wharton's Jelly hydrogel (DWJH) was combined with isolated CD56+Exos from CD56+UCSCs to fabricate DWJH/CD56+Exos. The in vitro studies were performed to characterize the DWJ (decellularized Wharton's Jelly). The injectability and rheological properties were assessed by shear rate and frequency sweep analysis. The biocompatibility and chondrogenic differentiation inducibility of DWJH/CD56+Exos were performed on human bone marrow mesenchymal stem cells (hBMSCs) and RAW 264.7 cells. The release dynamics was evaluated in vitro and in vivo experiments. As for the in vivo experiments, the operated rats that subjected to a 2 mm full-thickness longitudinal tear in right medial anterior meniscus were injected a single dose of DWJH/CD56+Exos. At 4 and 8 weeks postoperatively, torn meniscus healing and articular cartilage degeneration were evaluated by hematoxylin and eosin (H&E), safranin O/fast green (SO&FG), and Sirius red staining. In in vitro experiments, the injectable DWJH/CD56+Exos demonstrated excellent biocompatibility, exosome releasing efficiency, injectable property and chondrogenic inducibility. The results of in vivo experiments revealed that DWJH/CD56+Exos degraded over time, promoted meniscal chondrogenesis, organized meniscal extracellular matrix remodeling, safeguard articular cartilage and inhibited secondary cartilage degeneration, which accelerated further facilitated torn meniscus healing. The novel injectable DWJH/CD56+Exos promoted meniscal tear healing by promoting meniscal chondrogenesis, safeguarding articular cartilage, and inhibiting secondary cartilage degeneration.

Diagnosis and Treatment Strategies of Meniscus Root Tears: A Scoping Review

Background

Meniscus root tears comprise 10% to 21% of all meniscal tears. These tears alter knee biomechanics, elevating contact pressure, akin to a meniscectomy. Consequently, they are linked to advanced joint degeneration and cartilage damage in the affected compartment.

Purpose

To systematically evaluate and relate the current literature describing the diagnosis and treatment strategies for meniscus root tears.

Study Design

Scoping review; Level of evidence, 4.

Methods

This review was conducted following the guidelines of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) extension for scoping reviews. Inclusion criteria encompassed English-language clinical and preclinical research, technical notes, and narrative reviews on meniscus root tears. Exclusion criteria were studies on patellar tendon rupture, studies on medial patellofemoral ligament rupture with additional knee joint ligament injuries, studies of patients <16 years old, and studies involving open fractures. The data were summarized using a descriptive analysis and a thematic analysis.

Results

After 1425 articles were identified, 461 studies were included; 17% (n = 78) were case reports or case series, 15% (n = 71) were technical notes, 9% (n = 41) addressed aspects of diagnosis, 7% (n = 32 ) were narrative reviews, and 5% (n = 21) were systematic reviews or meta-analyses. Studies presenting original data comprised 57% (n = 262) of all included studies, and 97% of the studies were of evidence levels 3 to 5. Contributions were mainly from the United States (n = 123; 27%), Republic of Korea (n = 102; 22%), and Japan (n = 99; 21%). Many studies (n = 216; 47%) focused on the treatment and outcomes of meniscus root tears. A significant chronological surge in the quantity of studies addressing the diagnosis and treatment of meniscus root tears was evident, particularly over the past 3 years. Consensus was found regarding the definition of meniscus root tears, the advantages of early repair, and postoperative rehabilitation protocols. The variations in surgical techniques and operative strategies created the greatest amount of contention, along with clinical assessment and imaging modalities.

Conclusion

High-level evidence studies for diagnosing and managing meniscus root tears were scarce. A consensus has yet to be reached regarding the role of concomitant osteotomy, comparison of repair techniques, the use of a centralization stitch, patient factors affecting outcomes, and long-term outcomes of nonoperative management.

Clinical Outcomes of Exercise Rehabilitation for Degenerative Tibial Meniscal Tears: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective

This study aims to comprehensively evaluate the effectiveness of exercise rehabilitation therapy for patients with Degenerative Meniscal Lesions of the Tibia (DMLT), providing more effective and safer treatment options for DMLT patients and offering more reliable evidence-based medical recommendations.

Methods

Adhering to the PRISMA guidelines, this research conducted a literature search through databases such as PubMed, Web of Science, EMBASE, EBSCOhost, and Cochrane, with the search cut-off date being January 2024. Following the PICOS principles, a comprehensive search was conducted. Two researchers independently screened the literature and extracted data. Using R software, effect size analyses were conducted on indicators such as pain, knee joint function, lower limb muscle strength, and physical function in DMLT patients, with the significance level set at P<0.05, aiming to comprehensively assess the impact of exercise therapy on the rehabilitation outcomes for DMLT patients.

Results

The study included 12 randomized controlled trials, encompassing 1336 DMLT patients. Based on the quality assessment using the modified Jadad scale, the overall quality of the included studies was determined to be moderate.The meta-analysis showed that exercise therapy significantly reduced pain (WMD=-5.50, P<0.05), improved lower limb muscle strength (SMD=0.05, P<0.05), and enhanced physical function (SMD=0.65, P<0.05). Subgroup analyses revealed that, compared to surgery alone, exercise therapy combined with surgery had a significant effect on improving muscle strength and physical function. Functional training and home-based exercises showed more pronounced effects on specific indicators. The study results indicate that exercise therapy alone has limited effectiveness in improving knee joint function, and combining exercise with surgery does not show a significant advantage (P > 0.05). Additionally, subgroup analysis revealed no significant impact of intervention duration, exercise type, or patient age on functional improvement.

Conclusion

Exercise therapy has shown potential in alleviating pain, enhancing lower limb muscle strength, and improving mobility in patients with degenerative meniscal lesions of the tibia (DMLT). Functional training and varied rehabilitation exercises may provide effective pathways for long-term recovery in these patients.

Registration

This study has been registered in a prospective registry platform with the registration number: CRD42024518643.

Cellular senescence contributes to spontaneous repair of the rat meniscus

Cellular senescence, traditionally associated with aging and chronic diseases, has recently been identified as a potential facilitator of tissue regeneration via a senescence-associated secretory phenotype (SASP). In rodents, the meniscus is known to regenerate spontaneously from the surrounding synovium, but the mechanism, and especially its relationship to cellular senescence, remains unclear. This study investigated the contribution of cellular senescence to spontaneous repair of the rat meniscus. We created a rat partial medial meniscectomy (pMx) model to evaluate time-course changes in regenerative tissue. Immunohistochemistry revealed marked increases in p16 expression and senescence-associated beta-galactosidase (SA-β-gal) activity in the regenerating tissue at the early phase after pMx surgery. RNA sequencing of regenerating tissues identified the upregulation of genes related to aging, extracellular matrix organization, and cell proliferation. Fluorescence staining identified high expression of SOX9, a master regulator of cartilage/meniscus development, adjacent to p16-positive cells. In vitro investigations of the effect of SASP factors on synovial fibroblasts (SFs) demonstrated that conditioned medium from senescent SFs stimulated the proliferation and chondrogenic differentiation of normal SFs. In vivo histological evaluation to determine whether selective elimination of senescent cells with a senolytic drug (ABT-263) retarded spontaneous repair of meniscus in vivo confirmed that ABT-263 decreased the meniscus score and expression of SOX9, aggrecan, and type 1 collagen. Our findings indicate that transient senescent cell accumulation and SASP in regenerating tissues beneficially contribute to spontaneous repair of the rat meniscus. Further research into the molecular mechanism will provide a novel strategy for meniscus regeneration based on cellular senescence.

Unveiling the mechanical role of radial fibers in meniscal tissue: Toward structural biomimetics

The meniscus tissue is crucial for knee joint biomechanics and is frequently susceptible to injuries resulting in early-onset osteoarthritis. Consequently, the need for meniscal substitutes spurs ongoing development. The meniscus is a composite tissue reinforced with circumferential and radial collagenous fibers; the mechanical role of the latter has yet to be fully unveiled. Here, we investigated the role of radial fibers using a synergistic methodology combining meniscal tissue structure imaging, a computational knee joint model, and the fabrication of simple biomimetic composite laminates. These laminates mimic the basic structural units of the meniscus, utilizing longitudinal and transverse fibers equivalent to the circumferential and radial fibers in meniscal tissue. In the computational model, the absence of radial fibers resulted in stress concentration within the meniscus matrix and up to 800 % greater area at the same stress level. Furthermore, the contact pressure on the tibial cartilage increased drastically, affecting up to 322 % larger areas. Conversely, in models with radial fibers, we observed up to 25 % lower peak contact pressures and width changes of less than 0.1 %. Correspondingly, biomimetic composite laminates containing transverse fibers exhibited minor transverse deformations and smaller Poisson's ratios. They demonstrated structural shielding ability, maintaining their mechanical performance with the reduced amount of fibers in the loading direction, similar to the ability of the torn meniscus to carry and transfer loads to some extent. These results indicate that radial fibers are essential to distribute contact pressure and tensile stresses and prevent excessive deformations, suggesting the importance of incorporating them in novel designs of meniscal substitutes. STATEMENT OF SIGNIFICANCE: The organization of the collagen fibers in the meniscus tissue is crucial to its biomechanical function. Radially oriented fibers are an important structural element of the meniscus and greatly affect its mechanical behavior. However, despite their importance to the meniscus mechanical function, radially oriented fibers receive minor attention in meniscal substitute designs. Here, we used a synergistic methodology that combines imaging of the meniscal tissue structure, a structural computational model of the knee joint, and the fabrication of simplistic biomimetic composite laminates that mimic the basic structural units of the meniscus. Our findings highlight the importance of the radially oriented fibers, their mechanical role in the meniscus tissue, and their importance as a crucial element in engineering novel meniscal substitutes.

Efficacy and Long-Term Outcomes of Arthroscopic Meniscus Repair: A Systematic Review and Meta-Analysis

The objective of this systematic review and meta-analysis was to evaluate the efficacy and long-term outcomes of arthroscopic meniscus repair, focusing on success, failure, and reoperation rates. A comprehensive literature search was conducted across PubMed, EMBASE, Cochrane Library, and Scopus, including studies that involved patients undergoing arthroscopic meniscus repair with a minimum follow-up of two years. The quality of the included studies was assessed using the Cochrane Risk of Bias Tool for randomized controlled trials and the Newcastle-Ottawa Scale for observational studies. Meta-analyses were conducted using RStudio 4.3.1 software (RStudio Inc., Boston, MA), with pooled risk ratios (RR) and 95% confidence intervals (CIs) calculated for dichotomous outcomes using a random effects model. The meta-analysis included 10 studies totaling 1,004 patients. The pooled success rate for arthroscopic meniscus repair was 83% (95% CI: 77%-89%), while the pooled failure rate was 20% (95% CI: 15%-25%), and the pooled reoperation rate was 21% (95% CI: 17%-25%). Significant heterogeneity was observed across studies (I² > 50%). Subgroup analyses based on suture techniques and concurrent anterior cruciate ligament (ACL) reconstruction did not reveal significant outcome differences. Arthroscopic meniscus repair demonstrates high success rates and acceptable failure and reoperation rates, supporting its continued use in clinical practice. However, the variability in study quality and significant heterogeneity highlight the need for more rigorous, high-quality studies to refine techniques and better explore long-term outcomes.

Precision Repair of Zone-Specific Meniscal Injuries Using a Tunable Extracellular Matrix-Based Hydrogel System

Meniscus injuries present significant therapeutic challenges due to their limited self-healing capacity and diverse biological and mechanical properties across meniscal tissue. Conventional repair strategies neglect to replicate the complex zonal characteristics within the meniscus, resulting in suboptimal outcomes. In this study, we introduce an innovative, age- and stiffness-tunable meniscus decellularized extracellular matrix (DEM)-based hydrogel system designed for precision repair of heterogeneous, zonal-dependent meniscus injuries. By synthesizing age-dependent DEM hydrogels, we identified distinct cellular responses: fetal bovine meniscus-derived DEM promoted chondrogenic differentiation, while adult meniscus-derived DEM supported fibrochondrogenic phenotypes. The incorporation of methacrylate hyaluronic acid (MeHA) further refined the mechanical properties and injectability of the DEM-based hydrogels. The combination of age-dependent DEM with MeHA allowed for precise stiffness tuning, influencing cell differentiation and closely mimicking native tissue environments. In vivo tests confirmed the biocompatibility of hydrogels and their integration with native meniscus tissues. Furthermore, advanced 3D bioprinting techniques enabled the fabrication of hybrid hydrogels with biomaterial and mechanical gradients, effectively emulating the zonal properties of meniscus tissue and enhancing cell integration. This study represents a significant advancement in meniscus tissue engineering, providing a promising platform for customized regenerative therapies across a range of heterogeneous fibrous connective tissues.

Age and anatomical region-related differences in vascularization of the porcine meniscus using microcomputed tomography imaging

Meniscal lesions in vascularized regions are known to regenerate while lack of vascular supply leads to poor healing. Here, we developed and validated a novel methodology for three-dimensional structural analysis of meniscal vascular structures with high-resolution microcomputed tomography (µCT). We collected porcine medial menisci from 10 neonatal (not-developed meniscus, n-) and 10 adults (fully developed meniscus, a-). The menisci were cut into anatomical regions (anterior horn (n-AH and a-AH), central body (n-CB and a-CB), and posterior horn (n-PH and a-PH). Specimens were cut in half, fixed, and one specimen underwent critical point drying and µCT imaging, while other specimen underwent immunohistochemistry and vascularity biomarker CD31 staining for validation of µCT. Parameters describing vascular structures were calculated from µCT. The vascular network in neonatal spread throughout meniscus, while in adult was limited to a few vessels in outer region, mostly on femoral side. n-AH, n-CB, and n-PH had 20, 17, and 11 times greater vascular volume fraction than adult, respectively. Moreover, thickness of blood vessels, in three regions, was six times higher in adults than in neonatal. a-PH appeared to have higher vascular fraction, longer and thicker blood vessels than both a-AH and a-CB. Overall, neonatal regions had a higher number of blood vessels, more branching, and higher tortuosity compared to adult regions. For the first time, critical point drying-based µCT imaging allowed detailed three-dimensional visualization and quantitative analysis of vascularized meniscal structures. We showed more vascularity in neonatal menisci, while adult menisci had fewer and thicker vascularity especially limited to the femoral surface.

Meniscal Allograft versus Synthetic Graft in Treatment Outcomes of Meniscus Repair: A Mini-review and Meta-analysis

Meniscal injuries are highly correlated with osteoarthritis (OA) onset and progression. Although meniscal allograft transplantation (MAT) is a therapeutic option to restore meniscal anatomy, a shortage of donor material and the donor-derived infectious risk may be concerns in clinics. This review summarizes the literature reporting meniscus repair status in preclinical models and clinical practice using allografts or synthetic grafts. The advantages and limitations of biodegradable polymer-based meniscal scaffolds, applied in preclinical studies, are discussed. Then, the long-term treatment outcomes of patients with allografts or commercial synthetic scaffolds are compared. A total of 47 studies are included in our network meta-analysis. Compared with the meniscal allografts, the commercial synthetic products significantly improved clinical treatment outcomes in terms of the Knee Injury and Osteoarthritis Outcome Score (KOOS), Visual Analog Scale (VAS) scores, and Lysholm scores. In addition, development strategies for the next generation of novel synthetic scaffolds are proposed through optimization of structural design and fabrication, and selection of cell sources, external stimuli, and active ingredients. This review may inspire researchers and surgeons to design and fabricate clinic-orientated grafts with improved treatment outcomes.

Decreasing Incidence of Partial Meniscectomy and Increasing Incidence of Meniscus Preservation Surgery From 2010 to 2020 in the United States

PURPOSE

To characterize the incidence of meniscus surgery from 2010 to 2020 in the United States, using the metrics of age, sex, type of meniscus surgery, and Charlson Comorbidity Index (CCI).

METHODS

A retrospective analysis was performed using the PearlDiver national insurance claims database from 2010 to 2020. Meniscus surgeries were identified using Current Procedural Terminology codes. Patients were stratified by procedure type, age, biological sex, and CCI scores. Compound annual growth rate analysis and analysis of variance were performed to analyze the trends and demographic variables between cohorts.

RESULTS

Of 2,053,884 meniscus surgeries, 94.7% were meniscectomies, 0.3% were open repairs, 4.9% were arthroscopic repairs, and 0.1% were meniscal transplantations. Compound annual growth rate analysis displayed a 4.0% decrease per year in total meniscus surgery. For individual procedure types, the largest decrease was in meniscectomy, and the largest increase was in open repair. Patients undergoing meniscal transplantation were youngest, with the lowest CCI. Meniscectomy patients were oldest, and open repair patients had the highest average CCI. Most procedures were performed on female patients (52.4%) and patients in the 50- to 59-year age group (30.4%).

CONCLUSIONS

There was a sustained decrease in the incidence of total meniscus surgeries from 2010 to 2020. Meniscectomy was the procedure with the highest incidence, but it showed the most significant decline in usage over the study period. Conversely, meniscal repair and transplantation procedures increased during the study period.

LEVEL OF EVIDENCE

Level IV, epidemiologic study.

Corticosteroid injection of the knee within one month prior to meniscus repair increases the risk of repair failure requiring meniscectomy

OBJECTIVE

Meniscal tears are common knee injuries with limited endogenous healing capacity. This study aimed to investigate the association between the timing and administration of preoperative intra-articular corticosteroid injections (CSIs) and the risk of subsequent meniscectomy following meniscus repair.

METHODS

Using a national insurance claims database, patients aged 18-40 years undergoing meniscus repair within six months of tear diagnosis were studied. Patients were categorized based on whether they received preoperative CSIs within three intervals prior to repair. Multivariable logistic regression was used to analyze the risk of follow-up meniscectomy while controlling for various patient-related variables.

RESULTS

Among 5,390 patients meeting inclusion criteria, 201 received preoperative CSIs. The CSI group was older and had higher rates of diabetes, obesity, and knee osteoarthritis. The overall rate of follow-up meniscectomy did not differ between groups. However, CSIs performed within one month prior to repair were associated with significantly higher odds of subsequent meniscectomy compared to CSIs performed between three and six months prior. Obesity, tobacco use, and knee osteoarthritis were also independently associated with higher risk, while increasing age was associated with lower risk.

CONCLUSION

The study highlights an increased risk of repair failure requiring follow-up meniscectomy for patients receiving intra-articular CSIs within one month prior to meniscus repair. These findings suggest caution when considering CSIs as a treatment option for patients scheduled for meniscus repair. Further research is needed to establish optimal timing guidelines for CSIs in relation to meniscus repair and to understand the underlying mechanisms.

Biologic Augmentation of Isolated Meniscal Repair

PURPOSE OF REVIEW

The limited blood supply and intrinsic healing capacity of the meniscus contributes to suboptimal tissue regeneration following injury and surgical repair. Biologic augmentation techniques have been utilized in combination with isolated meniscal repair to improve tissue regeneration. Several innovative strategies such as Platelet-Rich Plasma (PRP), fibrin clots, mesenchymal stem cells (MSCs), bone marrow stimulation, meniscal scaffolds, and meniscal wrapping, are being explored to enhance repair outcomes. This article provides a comprehensive review of recent findings and conclusions regarding biologic augmentation techniques.

RECENT FINDINGS

Studies on PRP reveal mixed outcomes, with some suggesting benefits in reducing failure rates of isolated meniscal repair, while others question its efficacy. Fibrin clots and PRF (Platelet-rich fibrin), although promising, show inconsistent results and lack sufficient evidence for definitive conclusions. MSCs demonstrate potential in preclinical studies, but clinical trials have been limited and inconclusive. Bone marrow stimulation appears effective in certain contexts, but its broader applicability remains uncertain. Meniscal scaffolds, including CMI (Collagen Meniscal Implants) and Actifit (polyurethane scaffolds), show encouraging short- and mid-term outcomes but have not consistently surpassed traditional methods in the long term. Meniscal wrapping is infrequently studied but demonstrates positive short-term results with certain applications. The review reveals a diverse range of outcomes for biologic augmentation in meniscal repair. While certain techniques show promise, particularly in specific scenarios, the overall efficacy of these methods has yet to reach a consensus. The review underscores the necessity for standardized, high-quality research to establish the definitive effectiveness of these biologic augmentation methods.

Short-term outcomes of 43 dogs treated with arthroscopic suturing for meniscal tears associated with cranial cruciate ligament disease

OBJECTIVE

To describe short-term outcomes and complications in dogs receiving meniscal suturing and concurrent tibial plateau leveling osteotomy (TPLO) with or without augmentation with an extracapsular suture.

STUDY DESIGN

Retrospective case series.

ANIMALS

Forty-three client-owned dogs submitted for cruciate ligament disease.

METHODS

Dogs were included if meniscal suturing was performed during or after a TPLO procedure. Criteria included an unstable medial meniscus without evidence of a tear, a caudal vertical longitudinal tear with or without displacement, or if a bucket-handle tear was debrided and the remaining rim was unstable. Stifle stabilization was performed by either a standard TPLO or an augmented TPLO (TPLO + internal brace [IB]). Outcome measures included physical examination findings, radiographs, subjective gait examination, Liverpool Osteoarthritis in Dogs (LOAD) scores, and second-look arthroscopy.

RESULTS

Forty-four meniscal repairs were performed in 43 dogs. Five types of meniscal tears were treated employing eight suture materials. Complications were documented in 15 cases (34%). The stabilization technique had a significant impact on the outcome (p = .049): TPLO + IB had a 93.3% success rate and the success rate was 71.4% in the TPLO-only group.

CONCLUSION

Five types of meniscal pathology were addressed successfully in the study, indicating that currently accepted criteria for meniscal suturing in dogs may be overly conservative. The majority of complications were not related to the meniscal suturing itself and did not compromise the outcome. The stifle stabilization technique had an impact on outcome.

CLINICAL SIGNIFICANCE

The authors found arthroscopic meniscal suturing to be practical and successful in this patient population. Postoperative stifle stability had an impact on successful treatment.

Superior load-to-failure in an all-suture anchor system for all-inside meniscal repair compared to a PEEK-cage anchor system in an experimental cadaveric test setting

Purpose

The purpose of this study was to compare the biomechanical properties of a latest generation all-suture anchor repair device (ASARD) for meniscal repair with that of a latest generation PEEK-cage anchor repair device (PCARD) in an experimental setting using cadaveric menisci.

Methods

Twenty-six menisci were obtained from the knees of fresh body donors. Artificially created meniscal lesions were treated randomly, using a single stitch with either an ASARD or a PCARD. Cyclic biomechanical testing, utilising a universal material testing machine and following an established protocol, was carried out and load-to-failure (LTF), displacement, stiffness, and mode-of-failure (MOF) reported.

Results

Mean LTF was found to be 61% higher in the ASARD group at 107.10 N (standard deviation [SD], 42.34), compared to 65.86 N (SD, 27.42) in the PCARD group with statistical significance (p = 0.022). The ASARD exhibited a trend towards higher stiffness (10.35 N; SD, 3.92 versus 7.78 N; SD; 3.59) and higher displacement at cycles one, 100, and 499 (1.64, 3.27, and 4.17 mm versus 0.93, 2.19, and 2.83 mm) compared to the PCARD. Cheese wiring was the most common mode-of-failure in both groups (76.9%).

Conclusions

This study demonstrates that an ASARD shows a higher mean LTF than a PCARD when compared in an experimental biomechanical setting.

Level of evidence

Level III.

Meniscal Repair With Iliotibial Band Grafting and Collagen Membrane Wrapping Augmentation

This work contains a description of the modified Henning operation. This technique can be proven especially useful in difficult cases of damaged meniscus (complex injuries). It consists of three stages: stable suturing of the meniscus, placement of the graft from the iliotibial band on the meniscus, and covering the graft with a collagen membrane. Stitching the meniscus provides initial stabilization, the graft from the iliotibial band provides scaffolding for the reconstructed tissue, and the collagen membrane provides biological stimulation for healing.

Segond fracture: an indicator for increased risk of lateral meniscus injury in patients with acute anterior cruciate ligament ruptures

PURPOSE

The purpose of this study was to investigate the incidence and anatomic distribution of meniscus injury in patients who have sustained acute ACL injuries with and without concomitant Segond fracture. We hypothesized that patients who have sustained a torn ACL with a concomitant Segond fracture would have a higher incidence of lateral meniscal injuries than patients with an isolated ACL injury.

METHODS

Patients who underwent ACL reconstruction from 2012 to 2022 were retrospectively reviewed. Segond fractures were identified on knee radiographs. Inclusion criteria were age 18-40, injury during sports activity, and reconstruction within 90 days of injury. Sports activity, anatomic location of meniscus injury, and meniscus treatment were documented. Multivariable regression was used to identify predictors of meniscus injury/treatment.

RESULTS

There were 25 of 603 (4.1%) patients who had an ACL tear with concomitant Segond fracture. The incidence of lateral meniscus injury in the Segond group (72%) was significantly higher than in the non-Segond cohort (49%; p = 0.024). A significantly smaller proportion of medial meniscus injuries among patients with Segond fractures were repaired (23.1%) compared to the non-Segond group (54.2%; p = 0.043). Multivariate analysis found patients with Segond fractures to have increased odds of lateral meniscus injury (OR 2.68; [1.09, 6.60], p = 0.032) and were less likely to have medial meniscus injuries repaired (OR 0.35; [0.15, 0.81], p = 0.014). Additionally, males had increased odds of lateral meniscus injury (OR 1.54; [1.08 - 2.91], p = 0.017), which were more likely to require repair (OR 1.48; [1.02, 2.14], p = 0.038).

CONCLUSIONS

Among acute ACL injuries, the incidence of lateral meniscus injury is greater among patients with Segond fractures. Patients with Segond fracture were less likely to undergo repair of medial meniscal injuries.

Double-Needle Technique for Temporary Stabilization of Unstable Meniscal Tear During All-Inside Meniscal Repair

Meniscus tears are common in patients with primary or revision anterior cruciate ligament injuries. Given their important mechanical role in the joint, efforts are being made to repair as much of the meniscus tear as possible. However, all-inside repair might be challenging in case of an unstable tear due to the dislocation of the meniscal flap after deploying the first anchor. Therefore, we describe the details of our technique that allows the surgeon to stabilize the meniscal tear before all-inside repair, ensuring the reduction of the tear throughout the entire procedure.

Factors that influence medical students' decision to pursue a career in orthopaedics: a comprehensive analysis

PURPOSE

Selecting a postgraduate medical or surgical specialty is a significant decision for medical students, influenced by factors such as demographics, academic performance, satisfaction, work environments, personal aspirations, passion for a specific specialty, exposure to different fields during medical education, lifestyle considerations, financial factors, job market conditions, and prospects. Our research focused on orthopaedic surgery, a highly competitive specialty with many applicants and a low acceptance rate. We aimed to investigate the factors that contribute to the sustained interest in this specialty despite the challenges of securing a residency position. Hence, this study aims to examine the potential factors that influence students' decision to pursue a career as an orthopaedic surgeon.

METHODS

This cross-sectional study explores the perspectives and attitudes of 211 fifth-year medical students towards orthopaedic surgery after completing their clinical rotation at Mutah University's School of Medicine in 2022. The inclusion criteria for the study were limited to fifth-year medical students who successfully finished the orthopaedic rotation. A questionnaire was employed to evaluate students' firm commitment to orthopaedics as a prospective career and the degree of their current interest in the specialty.

RESULTS

The study involved 210 participants, with 99 selecting orthopaedics as their specialty and 111 pursuing alternatives. Furthermore, 41.4% expressed the intention to apply for orthopaedic residencies. Factors impacting orthopaedics selection included family/peer input (p = 0.002), prestige (p = 0.002), research prospects (p = 0.005), leadership potential (p = 0.011). Chi-square analysis showed associations between choosing orthopaedics and male gender (p = 0.028), parental occupation in musculoskeletal fields (p = 0.038), and elective rotations (p = 0.016).

CONCLUSION

This study examines the factors that influence medical students' career preferences in orthopaedic surgery, highlighting the significance of familial and peer influences, job prestige perceptions, gender considerations, parental involvement, elective rotations, research and teaching potential assessments, and aspirations for leadership roles. These findings reveal the complex array of factors that guide medical students toward orthopaedic surgery.

Silk fibroin hydrogel adhesive enables sealed-tight reconstruction of meniscus tears

Despite orientationally variant tears of the meniscus, suture repair is the current clinical gold treatment. However, inaccessible tears in company with re-tears susceptibility remain unresolved. To extend meniscal repair tools from the perspective of adhesion and regeneration, we design a dual functional biologic-released bioadhesive (S-PIL10) comprised of methacrylated silk fibroin crosslinked with phenylboronic acid-ionic liquid loading with growth factor TGF-β1, which integrates chemo-mechanical restoration with inner meniscal regeneration. Supramolecular interactions of β-sheets and hydrogen bonds richened by phenylboronic acid-ionic liquid (PIL) result in enhanced wet adhesion, swelling resistance, and anti-fatigue capabilities, compared to neat silk fibroin gel. Besides, elimination of reactive oxygen species (ROS) by S-PIL10 further fortifies localized meniscus tear repair by affecting inflammatory microenvironment with dynamic borate ester bonds, and S-PIL10 continuously releases TGF-β1 for cell recruitment and bridging of defect edge. In vivo rabbit models functionally evidence the seamless and dense reconstruction of torn meniscus, verifying that the concept of meniscus adhesive is feasible and providing a promising revolutionary strategy for preclinical research to repair meniscus tears.

Utility of Platelet-Rich Plasma Therapy in the Management of Meniscus Injuries: A narrative review

Menisci are crucial for knee joint functions and meniscal tears are common injuries, especially in sports activities. Platelet-rich plasma (PRP), which enhances healing, has emerged as a promising additive treatment for meniscus injuries, utilizing the regenerative properties of platelets and growth factors for improved clinical outcomes. In studies with a follow-up period of less than one year, the use of platelet-rich plasma (PRP) therapy for meniscus injuries showed significant improvements in knee symptoms and daily activity. Patients experienced enhanced outcomes in terms of pain reduction and increased sports activity, with MRI scans indicating stable meniscus conditions after six months. Studies with a follow-up of more than one year, however, did not find significant differences between groups treated with PRP and groups not treated with PRP in terms of various outcome measures, including pain and knee function. The vascularization of the menisci is vital for their proper function, and insufficient blood supply can affect healing of meniscal injuries. PRP therapy is used to enhance meniscal healing by introducing growth factors and anti-inflammatory agents. PRP therapy may enable athletes with meniscal tears to return to sports more quickly and has less rehabilitation duration. While PRP seems promising as an alternative to failed treatment or as an adjunct to treatment in the short term, its long-term effectiveness remains inconclusive. Patient preferences, commitment to therapy rehabilitation, and cost should all be considered on an individual basis.

Single-Dose Radial Extracorporeal Shock Wave Therapy Modulates Inflammation During Meniscal Tear Healing in the Avascular Zone

BACKGROUND

Extracorporeal shock wave therapy (ESWT) promotes tissue healing by modulating inflammation, which has implications for meniscal tear healing in the avascular zone.

PURPOSE

To evaluate the effects of a single dose of radial ESWT on the healing process and inflammation of the meniscus and knee joints after meniscal tears in the avascular zone.

STUDY DESIGN

Controlled laboratory study.

METHODS

Avascular tears were induced in the medial meniscus (MM) of 72 Sprague-Dawley rats. One week postoperatively, the rats received a single session of radial ESWT with a Power+ handpiece (ESWT group; n = 36) or with a fake handpiece (sham-ESWT group; n = 36). The rats were then euthanized at 2, 4, or 8 weeks postoperatively. The MMs were harvested for analysis of healing (hematoxylin-eosin, safranin O-Fast Green, and collagen type 2 staining) and inflammation (interleukin [IL]-1β and IL-6 staining). Lateral menisci and synovia were obtained to evaluate knee joint inflammation (enzyme-linked immunosorbent assay of IL-1β and IL-6). Cartilage degeneration was assessed in the femurs and tibial plateaus using safranin O-Fast Green staining.

RESULTS

The ESWT group showed significantly better meniscal healing scores than the sham-ESWT group at 4 (P = .0066) and 8 (P = .0050) weeks postoperatively. The IL-1β level was significantly higher in the sham-ESWT group than in the ESWT group at 2 (MM: P = .0009; knee joint: P = .0160) and 8 (MM: P = .0399; knee joint: P = .0001) weeks. The IL-6 level was significantly lower in the sham-ESWT group than in the ESWT group at 2 (knee joint: P = .0184) and 4 (knee joint: P = .0247) weeks but higher at 8 weeks (MM: P = .0169; knee joint: P = .0038). The sham group had significantly higher osteoarthritis scores than the ESWT group at 4 (tibial plateau: P = .0157) and 8 (femur: P = .0048; tibial plateau: P = .0359) weeks.

CONCLUSION

A single dose of radial ESWT promoted meniscal tear healing in the avascular zone, modulated inflammatory factors in the menisci and knee joints in rats, and alleviated cartilage degeneration.

CLINICAL RELEVANCE

Radial ESWT can be considered a potential option for improving meniscal tear healing in the avascular zone because of its ability to modulate inflammation.

Prevalence and Predictors of Concomitant Meniscal Surgery During Pediatric and Adolescent ACL Reconstruction: Analysis of 4729 Patients Over 20 Years at a Tertiary-Care Regional Children's Hospital

Background

The rate of concomitant meniscal procedures performed in conjunction with anterior cruciate ligament (ACL) reconstruction is increasing. Few studies have examined these procedures in high-risk pediatric cohorts.

Hypotheses

That (1) the rates of meniscal repair compared with meniscectomy would increase throughout the study period and (2) patient-related factors would be able to predict the type of meniscal operation, which would differ according to age.

Study Design

Cohort study (prevalence); Level of evidence, 2.

Methods

Natural language processing was used to extract clinical variables from notes of patients who underwent ACL reconstruction between 2000 and 2020 at a single institution. Patients were stratified to pediatric (5-13 years) and adolescent (14-19 years) cohorts. Linear regression was used to evaluate changes in the prevalence of concomitant meniscal surgery during the study period. Logistic regression was used to determine predictors of the need for and type of meniscal procedure.

Results

Of 4729 patients (mean age, 16 ± 2 years; 54.7% female) identified, 2458 patients (52%) underwent concomitant meniscal procedures (55% repair rate). The prevalence of lateral meniscal (LM) procedures increased in both pediatric and adolescent cohorts, whereas the prevalence of medial meniscal (MM) repair increased in the adolescent cohort (P = .02). In the adolescent cohort, older age was predictive of concomitant medial meniscectomy (P = .031). In the pediatric cohort, female sex was predictive of concomitant MM surgery and of undergoing lateral meniscectomy versus repair (P≤ .029). Female sex was associated with decreased odds of concomitant LM surgery in both cohorts (P≤ .018). Revision ACLR was predictive of concomitant MM surgery and of meniscectomy (medial and lateral) in the adolescent cohort (P < .001). Higher body mass index was associated with increased odds of undergoing medial meniscectomy versus repair in the pediatric cohort (P = .03).

Conclusion

More than half of the young patients who underwent ACLR had meniscal pathology warranting surgical intervention. The prevalence of MM repair compared with meniscectomy in adolescents increased throughout the study period. Patients who underwent revision ACLR were more likely to undergo concomitant meniscal surgeries, which were more often meniscectomy. Female sex had mixed effects in both the pediatric and adolescent cohorts.

Semitendinosus Autograft Transplant for Medial Meniscus

Treatment of meniscal tears has evolved over the last few decades, and preservation has now become the gold standard of treatment. Advancements in repair technique have extended the indication of repair. However, meniscectomy has to be performed in some situations. In these situations, meniscal allograft transplantation is considered the gold standard. But allografts are not available in every part of the world. Collagen implants and synthetic polymers are also advocated. But again, its limited research, availability, and high cost have restricted its widespread use. Many authors have advocated autograft transplantation, but there are no long-term results, and there is a lack of uniform surgical techniques. There is a technique described for lateral meniscus, but a medial meniscus autograft transplant technique is not very well elaborated. In this report, we aimed to describe a medial meniscus replacement technique using a hamstring autograft.

An Update on Orthobiologics: Cautious Optimism

Orthobiologics are rapidly growing in use given their potential to augment healing for multiple musculoskeletal conditions. Orthobiologics consist of a variety of treatments including platelet-rich plasma and stem cells that provide conceptual appeal in providing local delivery of growth factors and inflammation modulation. The lack of standardization in nomenclature and applications within the literature has led to a paucity of high-quality evidence to support their frequent use. The purpose of this review was to describe the current landscape of orthobiologics and the most recent evidence regarding their use.

Biomechanical Comparison of the Simple Suture Technique, Meniscal Matrix-Assisted Repair, and a Novel Meniscus Cap Suture Technique for Complex Meniscal Repair

Background

Meniscal repair is the gold standard for simple morphology tears. However, when the morphology and chronicity of the tear are less favorable, the success of the standard techniques is reduced.

Purpose/Hypothesis

To compare meniscal repair augmented by a new bioresorbable implant (Meniscus Cap) versus a traditional simple suture technique and the currently available augmented repair collagen matrix meniscus wrapping technique. It was hypothesized that the Meniscus Cap suture technique would increase ultimate failure load and less displacement during cyclic loading.

Study Design

Controlled laboratory study.

Methods

A total of 80 fresh porcine menisci were harvested. Complex tears were created in 60 menisci, and 20 intact menisci were tested as the control group. Repairs were performed on the 60 meniscal tears using 1 of the 3 techniques (20 menisci each): an inside-out H-suture group (SS), the collagen matrix wrapping technique (CMW), and the Meniscus Cap bioresorbable implant group (CM). The menisci were subjected to 500 loading cycles from 4 to 20 N at a frequency of 1 Hz, and the total displacement was recorded. Then, the specimens underwent load to failure testing at a rate of 3.15 mm/s, and the failure mode was noted.

Results

After 500 cycles of cyclic loading, there were no significant differences in displacement between the controls and CM group (0.524 vs 0.448 mm; P = .95). The displacement after the CM was significantly smaller compared with the CMW and the SS (0.448 vs 1.077 mm [P = .0009] and 0.448 vs 0.848 mm [P = .04], respectively). The ultimate load to failure was significantly greater for the controls and the CM group compared with the SS and CMW groups (controls, 1278.7 N and CM, 628.5 N vs CMW, 380.1 N and SS, 345.1 N; P < .05). The failure mode was suture breakage (suture failure) for all repairs.

Conclusion

In a porcine specimen meniscal repair model, the biomechanical properties of a novel Meniscus Cap repair technique were superior to that of the simple suture and CMW techniques.

Clinical Relevance

The results suggest that the Meniscal Cap repair technique may provide sufficient primary stability of the meniscal fixation even in the cases of complex meniscal tears.

Repair of a Radial Tear of the Meniscus Augmented With a Biocomposite Scaffold

Meniscal tears are a common musculoskeletal pathology in the United States, affecting 61 in every 100,000 people. Surgical repair is indicated for certain tear patterns to reduce the risk of joint degeneration, normalize contact forces in the knee, and help restore normal knee kinematics. However, radial meniscus tear repairs fail to completely heal 38% of the time due to tear characteristics, biology, surgical technique, and inadequate rehabilitation. Recent efforts have incorporated biological augmentation to enhance the healing potential of the meniscus. The BioBrace is a biocomposite scaffold designed to mechanically reinforce tissue and biologically enhance healing. The purpose of this article is to describe an all-inside, meniscal radial tear repair augmented with BioBrace.

Comparing Surgical Techniques for Meniscal Tears: A Systematic Review of Radiographic and Functional Outcomes

Meniscal tears are a common orthopedic injury. The management approaches for meniscal tears include both surgical and non-surgical procedures; however, the majority of the surgeons opt for various surgical interventions. This systematic review aimed to compare the outcomes of different surgical techniques for meniscal tears. The systemic search was carried out in various databases including PubMed, Web of Science, CINAHL, and Scopus. Studies that investigated surgical techniques for meniscal repair and published between 2010 to 2023 were included. Out of the 7,421 potential studies identified from databases and Google Scholar search, only 17 studies were included in our systemic review. The follow-up periods ranged from 6 weeks to 123 months. Adverse effects were reported in some studies, including joint line tenderness, swelling, and loss of flexion, while others reported no significant adverse events. Pull-out repair and refixation techniques demonstrated better clinical outcomes and slower arthritic progression than partial meniscectomy. Mason-Allen stitches and simple stitches yielded comparable results, and both inside-out and all-inside techniques had similar clinical and functional outcomes. This systematic review provides valuable insights into the outcomes of different surgical techniques for meniscal tears. Further studies with longer follow-up periods may help assess the long-term effectiveness of these surgical techniques.

Integrin α10β1-Selected Mesenchymal Stem Cells Reduce Pain and Cartilage Degradation and Increase Immunomodulation in an Equine Osteoarthritis Model

OBJECTIVE

Integrin α10β1-selected mesenchymal stem cells (integrin α10-MSCs) have previously shown potential in treating cartilage damage and osteoarthritis (OA) in vitro and in animal models in vivo. The aim of this study was to further investigate disease-modifying effects of integrin α10-MSCs.

DESIGN

OA was surgically induced in 17 horses. Eighteen days after surgery, horses received 2 × 107 integrin α10-MSCs intra-articularly or were left untreated. Lameness and response to carpal flexion was assessed weekly along with synovial fluid (SF) analysis. On day 52 after treatment, horses were euthanized, and carpi were evaluated by computed tomography (CT), MRI, histology, and for macroscopic pathology and integrin α10-MSCs were traced in the joint tissues.

RESULTS

Lameness and response to carpal flexion significantly improved over time following integrin α10-MSC treatment. Treated horses had milder macroscopic cartilage pathology and lower cartilage histology scores than the untreated group. Prostaglandin E2 and interleukin-10 increased in the SF after integrin α10-MSC injection. Integrin α10-MSCs were found in SF from treated horses up to day 17 after treatment, and in the articular cartilage and subchondral bone from 5 of 8 treated horses after euthanasia at 52 days after treatment. The integrin α10-MSC injection did not cause joint flare.

CONCLUSION

This study demonstrates that intra-articular (IA) injection of integrin α10-MSCs appears to be safe, alleviate pathological changes in the joint, and improve joint function in an equine post-traumatic osteoarthritis (PTOA) model. The results suggest that integrin α10-MSCs hold promise as a disease-modifying osteoarthritis drug (DMOAD).

Bioprinting of scaled-up meniscal grafts by spatially patterning phenotypically distinct meniscus progenitor cells within melt electrowritten scaffolds

Meniscus injuries are a common problem in orthopedic medicine and are associated with a significantly increased risk of developing osteoarthritis. While developments have been made in the field of meniscus regeneration, the engineering of cell-laden constructs that mimic the complex structure, composition and biomechanics of the native tissue remains a significant challenge. This can be linked to the use of cells that are not phenotypically representative of the different zones of the meniscus, and an inability to direct the spatial organization of engineered meniscal tissues. In this study we investigated the potential of zone-specific meniscus progenitor cells (MPCs) to generate functional meniscal tissue following their deposition into melt electrowritten (MEW) scaffolds. We first confirmed that fibronectin selected MPCs from the inner and outer regions of the meniscus maintain their differentiation capacity with prolonged monolayer expansion, opening their use within advanced biofabrication strategies. By depositing MPCs within MEW scaffolds with elongated pore shapes, which functioned as physical boundaries to direct cell growth and extracellular matrix production, we were able to bioprint anisotropic fibrocartilaginous tissues with preferentially aligned collagen networks. Furthermore, by using MPCs isolated from the inner (iMPCs) and outer (oMPCs) zone of the meniscus, we were able to bioprint phenotypically distinct constructs mimicking aspects of the native tissue. An iterative MEW process was then implemented to print scaffolds with a similar wedged-shaped profile to that of the native meniscus, into which we deposited iMPCs and oMPCs in a spatially controlled manner. This process allowed us to engineer sulfated glycosaminoglycan and collagen rich constructs mimicking the geometry of the meniscus, with MPCs generating a more fibrocartilage-like tissue compared to the mesenchymal stromal/stem cells. Taken together, these results demonstrate how the convergence of emerging biofabrication platforms with tissue-specific progenitor cells can enable the engineering of complex tissues such as the meniscus.

Continuous Vertical Inside-Out Versus Traditional Vertical Inside-Out Meniscal Repair: A Biomechanical Comparison

Background

Biomechanical assessment of meniscal repairs is essential for evaluating different meniscal suturing methods and techniques. The continuous meniscal suture technique is a newer method of meniscal repair that may have biomechanical differences compared with traditional techniques.

Purpose

To evaluate the displacement, stiffness after cyclical loading, and load to failure for a continuous vertical inside-out meniscal suture versus a traditional vertical inside-out meniscal suture in a porcine medial meniscus.

Study Design

Controlled laboratory study.

Methods

A total of 28 porcine knees were acquired and divided into 2 test groups of 14 medial meniscus each. A 2.0-cm longitudinal red-white zone cut was made in the body of the medial meniscus for each knee. The continuous suture (CS) group received 4 vertical stitches performed with a continuous vertical meniscal suture technique, and the inside-out suture (IO) group received a traditional vertical suture with 4 stitches. Two traction tapes were passed between the sutures and positioned in the biomechanical testing fixture device. Each specimen underwent load-to-failure testing at 5 mm/s, and displacement, system stiffness, and maximum load to failure were compared between the groups.

Results

The displacement after the cyclic test was 0.53 ± 0.12 and 0.48 ± 0.07 mm for the CS and IO groups, respectively. There was no significant difference between the groups (P = .2792). The stiffness at the ultimate load testing was 36.3 ± 1.9 and 35.3 ± 2.4 N/mm for groups CS and IO, respectively, with no significant difference between the groups (P = .2557). In the load-to-failure test, the ultimate load was 218.2 ± 63.9 and 238.3 ± 71.3 N in the CS and IO groups, respectively, with no significant group differences (P = .3062).

Conclusion

A continuous vertical meniscal suture created a configuration for treating longitudinal meniscal lesions that was beneficial and biomechanically similar to a traditional vertical suture technique.

Clinical Relevance

The study findings indicate that use of the continuous vertical inside-out meniscal suture technique is a possible therapeutic option.

Allografts for partial meniscus repair: an in vitro and ex vivo meniscus culture study

The purpose of this study was to evaluate the treatment potential of a human-derived demineralized scaffold, Spongioflex® (SPX), in partial meniscal lesions by employing in vitro models. In the first step, the differentiation potential of human meniscal cells (MCs) was investigated. In the next step, the ability of SPX to accommodate and support the adherence and/or growth of MCs while maintaining their fibroblastic/chondrocytic properties was studied. Control scaffolds, including bovine collagen meniscus implant (CMI) and human meniscus allograft (M-Allo), were used for comparison purposes. In addition, the migration tendency of MCs from fresh donor meniscal tissue into SPX was investigated in an ex vivo model. The results showed that MCs cultured in osteogenic medium did not differentiate into osteogenic cells or form significant calcium phosphate deposits, although AP activity was relatively increased in these cells. Culturing cells on the scaffolds revealed increased viability on SPX compared to the other scaffold materials. Collagen I synthesis, assessed by ELISA, was similar in cells cultured in 2D and on SPX. MCs on micro-porous SPX (weight >0.5 g/cm3) exhibited increased osteogenic differentiation indicated by upregulated expression of ALP and RUNX2, while also showing upregulated expression of the chondrogen-specific SOX9 and ACAN genes. Ingrowth of cells on SPX was observed after 28 days of cultivation. Overall, the results suggest that SPX could be a promising biocompatible scaffold for meniscal regeneration.

Modulating pentenoate-functionalized hyaluronic acid hydrogel network properties for meniscal fibrochondrocyte mechanotransduction

Knee meniscus tears are one of the most common musculoskeletal injuries. While meniscus replacements using allografts or biomaterial-based scaffolds are available, these treatments rarely result in integrated, functional tissue. Understanding mechanotransducive signaling cues that promote a meniscal cell regenerative phenotype is critical to developing therapies that promote tissue regeneration rather than fibrosis after injury. The purpose of this study was to develop a hyaluronic acid (HA) hydrogel system with tunable crosslinked network properties by modulating the degree of substitution (DoS) of reactive-ene groups to investigate mechanotransducive cues received by meniscal fibrochondrocytes (MFCs) from their microenvironment. A thiol-ene step-growth polymerization crosslinking mechanism was employed using pentenoate-functionalized hyaluronic acid (PHA) and dithiothreitol to achieve tunability of the chemical crosslinks and resulting network properties. Increased crosslink density, reduced swelling, and increased compressive modulus (60-1020 kPa) were observed with increasing DoS. Osmotic deswelling effects were apparent in PBS and DMEM+ compared to water; swelling ratios and compressive moduli were decreased in the ionic buffers. Frequency sweep studies showed storage and loss moduli of hydrogels at 1 Hz approach reported meniscus values and showed increasing viscous response with increasing DoS. The degradation rate increased with decreasing DoS. Lastly, modulating PHA hydrogel surface modulus resulted in control of MFC morphology, suggesting relatively soft hydrogels (E = 60 ± 35 kPa) promote more inner meniscus phenotype compared to rigid hydrogels (E = 610 ± 66 kPa). Overall, these results highlight the use of -ene DoS modulation in PHA hydrogels to tune crosslink density and physical properties to understand mechanotransduction mechanisms required to promote meniscus regeneration.

How Efficient Is ChatGPT in Accessing Accurate and Quality Health-Related Information?

Background and objective The field of artificial intelligence (AI) is advancing at a rapid pace, impacting all aspects of human life. Chat Generative Pre-trained Transformer (ChatGPT), which represents one of AI's most recent and remarkable achievements, has garnered significant attention and popularity in the academic community. ChatGPT, a language model-based chatbot developed by OpenAI, responds quickly and provides answers to the questions put to it. This chatbot has the ability to gather content from a variety of sources on the internet. However, its success in providing correct information has not yet been comprehensively analyzed. In light of this, this study aimed to engage in a comparative content analysis of health-related information provided by ChatGPT and a few selected websites. Methods We performed a qualitative analysis of data obtained from various information sources by using the DISCERN score and the Journal of the American Medical Association (JAMA) benchmark criteria. In addition, readability levels of the content were measured by using the Flesch-Kincaid grade level, Gunning Fog Index, and Simple Measure of Gobbledygook (SMOG) index. Results Based on our findings, there was no statistically significant difference between the websites and ChatGPT in DISCERN scores. However, the JAMA score was statistically significantly higher for websites. With regard to the Flesch-Kincaid grade level, Gunning Fog Index, and SMOG index values, the data obtained from the websites had higher readability. Conclusion Although AI is starting to play a significant role in our everyday lives, it has yet to surpass traditional methods of accessing information in terms of readability and reliability.

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.

Platelet-Rich Plasma and Marrow Venting May Serve as Cost-Effective Augmentation Techniques for Isolated Meniscal Repair: A Decision-Analytical Markov Model-Based Analysis

PURPOSE

To evaluate the cost-effectiveness of 3 isolated meniscal repair (IMR) treatment strategies: platelet-rich plasma (PRP)-augmented IMR, IMR with a marrow venting procedure (MVP), and IMR without biological augmentation.

METHODS

A Markov model was developed to evaluate the baseline case: a young adult patient meeting the indications for IMR. Health utility values, failure rates, and transition probabilities were derived from the published literature. Costs were determined based on the typical patient undergoing IMR at an outpatient surgery center. Outcome measures included costs, quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratio (ICER).

RESULTS

Total costs of IMR with an MVP were $8,250; PRP-augmented IMR, $12,031; and IMR without PRP or an MVP, $13,326. PRP-augmented IMR resulted in an additional 2.16 QALYs, whereas IMR with an MVP produced slightly fewer QALYs, at 2.13. Non-augmented repair produced a modeled gain of 2.02 QALYs. The ICER comparing PRP-augmented IMR versus MVP-augmented IMR was $161,742/QALY, which fell well above the $50,000 willingness-to-pay threshold.

CONCLUSIONS

IMR with biological augmentation (MVP or PRP) resulted in a higher number of QALYs and lower costs than non-augmented IMR, suggesting that biological augmentation is cost-effective. Total costs of IMR with an MVP were significantly lower than those of PRP-augmented IMR, whereas the number of additional QALYs produced by PRP-augmented IMR was only slightly higher than that produced by IMR with an MVP. As a result, neither treatment dominated over the other. However, because the ICER of PRP-augmented IMR fell well above the $50,000 willingness-to-pay threshold, IMR with an MVP was determined to be the overall cost-effective treatment strategy in the setting of young adult patients with isolated meniscal tears.

LEVEL OF EVIDENCE

Level III, economic and decision analysis.

[Research progress of knee meniscal repair techniques]

Objective

To review the research progress of meniscus repair in recent years, in order to provide help for the clinical decision-making of meniscus injury treatment.

Methods

The domestic and foreign literature related to meniscal repair in recent years was extensively reviewed to summarize the reasons for the prevalence of meniscal repair, surgical indications, various repair methods and long-term effectiveness, the need to deal with mechanical structural abnormalities, biological enhancement repair technology, rehabilitation treatment, and so on.

Results

In order to delay the occurrence of osteoarthritis, the best treatment of meniscus has undergone an important change from partial meniscectomy to meniscal repair, and the indications for meniscal repair have been expanding. The mid- and long-term effectiveness of different meniscal repair methods are ideal. During meniscus repair, the abnormality of lower limb force line and meniscus protrusion should be corrected at the same time. There are controversies about the biological enhancement technology to promote meniscus healing and rehabilitation programs, which need further study.

Conclusion

Meniscal repair can restore the normal mechanical conduction of lower limbs and reduce the incidence of traumatic osteoarthritis, but the poor blood supply and healing ability of meniscal tissue bring difficulties to meniscal repair. Further development of new biological enhanced repair technology and individualized rehabilitation program and verification of its effectiveness will be an important research direction.

Clinical, Radiographic, and MRI Evaluation of All-Inside Medial Meniscus Posterior Root Repair via Suture Fixation to the Posterior Cruciate Ligament Versus Partial Meniscectomy: Results at 3-Year Follow-up

Background

Medial meniscus posterior root tears (MMPRTs) disrupt the integrity and hoop tension of the meniscus, leading to cartilage degeneration and accelerated osteoarthritis (OA) progression. The management of patients with MMPRT is controversial, and the efficacy of different treatment options is unclear.

Purpose

To compare the clinical, radiographic, and magnetic resonance imaging (MRI) outcomes of patients with MMPRT between trans-posterior cruciate ligament (trans-PCL) all-inside repair and partial meniscectomy.

Study Design

Cohort study; Level of evidence, 3.

Methods

We identified patients with MMPRT who underwent trans-PCL all-inside repair (group AR) or partial meniscectomy (group PM) between 2015 and 2019 at a single institution. The trans-PCL all-inside repair was performed by suturing the torn meniscus root to the PCL fibers. Patient-reported outcomes as well as radiographic and MRI outcomes were collected at baseline and final follow-up. Clinical failure was defined as conversion to total knee arthroplasty (TKA), and Kaplan-Meier survival analysis was used to investigate the survival rates of patients with different surgical procedures.

Results

Included were 29 patients in group AR and 31 patients in group PM (mean age, 62.69 and 60.68 years, respectively; mean follow-up, 2.91 ± 1.33 and 3.45 ± 1.50 years, respectively). There were no differences in baseline patient characteristics between the groups. All patient-reported outcome scores improved significantly in both groups at the final follow-up. When we compared final outcomes between the groups, group AR had less joint space narrowing (P = .010), less Kellgren-Lawrence OA grade progression (P = .002), and less medial meniscal extrusion (MME; P = .002) than group PM. In addition, group AR showed less progression of bone marrow lesions and cartilage lesions (P < .05) than group PM. The rate of conversion to TKA was 6.90% in group AR and 29.0% in group PM. The 5-year survival rates in the AR and PM groups were 82.6% and 59.8%, respectively (P = .153).

Conclusion

Trans-PCL all-inside repair for MMPRTs was associated with greater improvement in clinical function, better radiographic results, less MME and cartilage degeneration, and a lower rate of subsequent TKA compared with partial meniscectomy.

Suspension bath bioprinting and maturation of anisotropic meniscal constructs

Due to limited intrinsic healing capacity of the meniscus, meniscal injuries pose a significant clinical challenge. The most common method for treatment of damaged meniscal tissues, meniscectomy, leads to improper loading within the knee joint, which can increase the risk of osteoarthritis. Thus, there is a clinical need for the development of constructs for meniscal repair that better replicate meniscal tissue organization to improve load distributions and function over time. Advanced three-dimensional bioprinting technologies such as suspension bath bioprinting provide some key advantages, such as the ability to support the fabrication of complex structures using non-viscous bioinks. In this work, the suspension bath printing process is utilized to print anisotropic constructs with a unique bioink that contains embedded hydrogel fibers that align via shear stresses during printing. Constructs with and without fibers are printed and then cultured for up to 56 din vitroin a custom clamping system. Printed constructs with fibers demonstrate increased cell and collagen alignment, as well as enhanced tensile moduli when compared to constructs printed without fibers. This work advances the use of biofabrication to develop anisotropic constructs that can be utilized for the repair of meniscal tissue.

Diagnostic Accuracy of 128-Slice Single-Source CT for the Detection of Dislocated Bucket Handle Meniscal Tears in the Setting of an Acute Knee Trauma—Correlation with MRI and Arthroscopy

(1) Background: Meniscal tears are amongst the most common knee injuries. Dislocated bucket handle meniscal tears in particular should receive early intervention. The purpose of this study was to evaluate the diagnostic performance of CT in detecting dislocated bucket handle meniscal tears compared with the gold-standard MRI and arthroscopy. (2) Methods: Retrospectively, 96 consecutive patients underwent clinically indicated CT of the knee for suspected acute traumatic knee injuries (standard study protocol, 120 kV, 90 mAs). Inclusion criteria were the absence of an acute fracture on CT and a timely MRI (<6 months). Corresponding arthroscopy was assessed. Two experienced musculoskeletal radiologists analyzed the images for dislocated bucket handle meniscal tears, associated signs thereof (double posterior cruciate ligament sign, double delta sign, disproportional posterior horn sign), and subjective diagnostic confidence on a 5-point-Likert scale (1 = ‘non-diagnostic image quality’, 5 = ‘very confident’). (3) Results: Dislocated bucket handle meniscal tears were detected on CT by standard three-plane bone kernel reconstructions with a sensitivity of 90.7% and a specificity of 99.3% by transferring the knowledge of established MRI signs. The additional use of soft-tissue kernel reconstructions in three planes increased the sensitivity by 4.0% to 94.7%, specificity to 100%, inter-rater agreement to 1.0, and the diagnostic confidence of both readers improved to a median 4/5 (‘confident’) in both readers. (4) Conclusions: Trauma CT scan of the knee with three-plane soft-tissue reconstructions delivers the potential for the detection of dislocated bucket handle meniscal tears with very high diagnostic accuracy.

Efficacy and safety of arthroscopic surgery combined with hyaluronic acid for meniscal injuries: A systematic review and meta-analysis of randomized controlled studies

OBJECTIVE

The efficacy and safety of arthroscopic surgery combined with hyaluronic acid in the treatment of meniscal injuries were evaluated by Meta-analysis to provide an evidence-based basis for the selection of clinical treatment options.

METHODS

PubMed, Cochrane Library, EMBASE, Scopus, Web of Science English databases, and Chinese databases of China National Knowledge Infrastructure, WAN FANG, VIP, and China SinoMed had been searched up to June 2021. Quality evaluation was performed concerning the Cochrane Systematic Evaluation Tool. The obtained data were analyzed using the statistical software Review Manager 5.3.

RESULTS

Eleven randomized controlled trials with a total of 955 patients were eventually included, 473 in the arthroscopic combined with hyaluronic acid group (combined treatment group) and 482 in the arthroscopy alone group (surgery group). The results of the study revealed that the excellent treatment [OR = 3.44, 95% CI (2.10, 5.65), p < .00,001], the VAS score [MD = -0.99, 95% CI (-1.50, -0.48), p = .0002], the Lysholm score [MD = 9.70, 95% CI (6.41, 12.99), p < .00,001] and the joint mobility [MD = 6.31, 95% CI (0.84, 11.78), p = .02] of the combined treatment group were significantly better than the surgery group, the difference was statistically significant. The complications rate was comparable in both groups [OR = 0.86, 95% CI (0.29, 2.53), p = .78], with no statistically significant difference.

CONCLUSION

Arthroscopic surgery combined with hyaluronic acid for meniscal injury can improve the efficiency of treatment compared with arthroscopic surgery alone, as well as the efficacy in relieving joint pain and improving joint function and mobility, without increasing the incidence of complications. Arthroscopic surgery combined with hyaluronic acid administration has good effectiveness and safety profile. Therefore, hyaluronic acid supplementation is recommended after arthroscopic surgery when treating meniscal injuries.

Mapping knowledge structure and research trends of knee osteoarthritis with meniscus in two decades: A bibliometric analysis

BACKGROUND

Knee osteoarthritis (KOA) is a chronic degenerative disease that is closely related to the meniscus. Currently, no bibliometric studies have jointly analyzed KOA and the meniscus. This study aimed to provide a comprehensive analysis of the knowledge structure of KOA and the meniscus across two decades and to identify the emerging research trends from a bibliometric perspective.

METHODS

All articles reporting KOA and the meniscus from 2001 to 2021 were obtained from the Web of Science Core Collection. R software, CiteSpace, VOS Viewer, and Microsoft Excel were used to analyze the publications including the authors, cited authors, journals, cited journals, country of research, institutions, and research focus. These data were used to generate visual knowledge maps of the outputs.

RESULTS

A total of 3,218 articles were retrieved. Guermazi was identified as the author who had contributed the most to the field and Osteoarthritis and Cartilage was identified as the most productive research journal. The United States is the global leader in the field and the center for international cooperation with less international collaboration occurring in Eastern Asia. Boston University was the most prolific institution. According to the data, "articular-cartilage," "meniscectomy," "follow-up," "anterior cruciate ligament," and "cartilage" were identified as research hotspots in the field. "Consequences," "prognostic-factors," and "receptor" were predicted as future hot topics of research.

CONCLUSIONS

This study is the first comprehensive bibliometric study to jointly analyze KOA and the meniscus. Our data enable a better understanding of research trends and identify research hotspots and gaps in knowledge across the field. Our findings provide practical information for researchers to better understand the key research areas and identify the research frontiers and future hot topics.

The role of patient characteristics and the effects of angiogenic therapies on the microvasculature of the meniscus: A systematic review

BACKGROUND

Considerable interindividual variation in meniscal microvascularization has been reported. The purpose of this review was to identify which patient characteristics affect meniscal microvascularization and provide a structured overview of angiogenic therapies that influence meniscal neovascularization.

METHODS

A systematic literature search was undertaken using PubMed, Embase, Web of Science, Cochrane library and Emcare from inception to November 2021. Studies reporting on (1) Patient characteristics that affect meniscal microvascularization, or (2) Therapies that induce neovascularization in meniscal tissue were included. Studies were graded in quality using the Anatomical Quality Assessment (AQUA) tool. The study was registered with PROSPERO(ID:CRD42021242479).

RESULTS

Thirteen studies reported on patient characteristics and eleven on angiogenic therapies. The influence of Age, Degenerative knee, Gender, and Race was reported. Age is the most studied factor. The entire meniscus is vascularized around birth. With increasing age, vascularization decreases from the inner to the peripheral margin. Around 11 years, blood vessels are primarily located in the peripheral third of the menisci. There seems to be a further decrease in vascularization with increasing age in adults, yet conflicting literature exists. Degenerative changes of the knee also seem to influence meniscal vascularization, but evidence is limited. Angiogenic therapies to improve meniscal vascularization have only been studied in preclinical setting. The use of synovial flap transplantation, stem cell therapy, vascular endothelial growth factor, and angiogenin has shown promising results.

CONCLUSION

To decrease failure rates of meniscal repair, a better understanding of patient-specific vascular anatomy is essential. Translational clinical research is needed to investigate the clinical value of angiogenic therapies.

Treatment strategies for meniscal lesions: from past to prospective therapeutics

Menisci play an important role in the biomechanics of knee joint function, including loading transmission, joint lubrication, prevention of soft tissue impingement during motion and joint stability. Meniscal repair presents a challenge due to a lack of vascularization that limits the healing capacity of meniscal tissue. In this review, the authors aimed to untangle the available treatment options for repairing meniscal tears. Various surgical procedures have been developed to treat meniscal tears; however, clinical outcomes are limited. Consequently, numerous researchers have focused on different treatments such as the application of exogenous and/or autologous growth factors, scaffolds including tissue-derived matrix, cell-based therapy and miRNA-210. The authors present current and prospective treatment strategies for meniscal lesions.

Effects of proprioceptive training in the recovery of patients submitted to meniscus surgery: systematic review and meta-analysis

OBJECTIVE

To evaluate the effects of proprioceptive training on rehabilitation of knee after arthroscopic partial meniscectomy (APM).

DESIGN

PubMed, EMBASE, The Cochrane Library, Web of Science, China National Knowledge Infrastructure, Technology Periodical Database, WanFang Data and China Biology Medicine were searched until December 2021 for randomised controlled trials.

PARTICIPANTS

Patients who have undergone APM for meniscus injury caused by traumatic tear.

RESULTS

A total of 9 studies with 453 patients were included in this study for meta-analysis, and 2/9 with high quality, 6/9 with moderate quality. Based on very low quality evidence, the pooled effect showed significant improvement for proprioceptive training group in proprioception test (p<0.05, I²=18%), knee extensor muscle strength (p<0.05, I²=29%), knee flexor muscle strength (p<0.05, I²=0%) and knee function score (p<0.05, I²=0%) compared with conventional training group in patients after APM.

CONCLUSION

Based on very low quality, adding proprioceptive training to conventional rehabilitation programmes might be beneficial to promote functional recovery for patients after APM. It is necessary to carry out more samples and higher quality large-scale studies to provide high evidence in the future.

PROSPERO REGISTRATION NUMBER

CRD42020213201.

Knee Joint Menisci Are Shock Absorbers: A Biomechanical In-Vitro Study on Porcine Stifle Joints

The aim of this biomechanical in vitro study was to answer the question whether the meniscus acts as a shock absorber in the knee joint or not. The soft tissue of fourteen porcine knee joints was removed, leaving the capsuloligamentous structures intact. The joints were mounted in 45° neutral knee flexion in a previously validated droptower setup. Six joints were exposed to an impact load of 3.54 J, and the resultant loss factor (η) was calculated. Then, the setup was modified to allow sinusoidal loading under dynamic mechanical analysis (DMA) conditions. The remaining eight knee joints were exposed to 10 frequencies ranging from 0.1 to 5 Hz at a static load of 1210 N and a superimposed sinusoidal load of 910 N (2.12 times body weight). Forces (F) and deformation (l) were continuously recorded, and the loss factor (tan δ) was calculated. For both experiments, four meniscus states (intact, medial posterior root avulsion, medial meniscectomy, and total lateral and medial meniscectomy) were investigated. During the droptower experiments, the intact state indicated a loss factor of η = 0.1. Except for the root avulsion state (−15%, p = 0.12), the loss factor decreased (p &lt; 0.046) up to 68% for the total meniscectomy state (p = 0.028) when compared to the intact state. Sinusoidal DMA testing revealed that knees with an intact meniscus had the highest loss factors, ranging from 0.10 to 0.15. Any surgical manipulation lowered the damping ability: Medial meniscectomy resulted in a reduction of 24%, while the resection of both menisci lowered tan δ by 18% compared to the intact state. This biomechanical in vitro study indicates that the shock-absorbing ability of a knee joint is lower when meniscal tissue is resected. In other words, the meniscus contributes to the shock absorption of the knee joint not only during impact loads, but also during sinusoidal loads. The findings may have an impact on the rehabilitation of young, meniscectomized patients who want to return to sports. Consequently, such patients are exposed to critical loads on the articular cartilage, especially when performing sports with recurring impact loads transmitted through the knee joint surfaces.

The prevalence and parameters of fabella and its association with medial meniscal tear in China: a retrospective study of 1011 knees

Background

Fabella is a sesamoid bone of knee that has potential biomechanical function. We aimed to examine the fabellar prevalence and parameters in Chinese population and test the hypothesis that fabellar presence and morphology were associated with meniscus tear or ligament injury.

Methods

A total of 1011 knee magnetic resonance imaging scans from 979 patients with knee pain were analyzed retrospectively. The exclusion criteria are postsurgical scans, difficulty in fabella discrimination, conditions not suitable for measurement, and unsatisfied image. The fabellar presence and its parameters (length, width and thickness) were documented. The association between fabellar presence and meniscus tear or ligament injury were assessed by chi-square test, in all knees and subgroups (age, gender, side, lesion part). The correlation of fabellar presence and parameters with advancing age was assessed by Spearman correlation analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to investigate whether factors related with meniscus tear or ligament injury. Diagnostic performance of risk factors was assessed by receiver operating characteristic (ROC) analysis.

Results

The overall prevalence of fabellae was 39.8% (402/1011 knees) and increased with the increasing age (r = 0.237, P < 0.001). The size of the fabellae differed according to genders, age, and presence of articulating grooves. Fabella presented more often in knees with medial meniscus (MM) tears (66.7% vs 33.8%; P < 0.001) with a multivariate OR of 2.960 (95% CI, 1.853–3.903). The association remained in all tear parts (anterior, middle, and posterior), and in younger (age < 50 years) and older patients (age ≥ 50 years). Age, fabellar length, width, length/thickness ratio and width/thickness ratio yielded an area under the ROC curve (AUC) of 0.604–0.766 to predict an MM tear. In combination with age, fabellar width and length/thickness ratio, the AUC was improved 0.791 (95% CI, 0.744–0.837), with a sensitivity of 73.0% and a specificity of 74.6%.

Conclusion

The presence of fabellae, increased fabellar length and width as well as flatter fabellar morphology, are significantly associated with an increased risk for MM tear. These findings might aid clinicians in identifying patients at risk for a MM tear and informing them.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05092-4.

Fibronectin Adherent Cell Populations Derived From Avascular and Vascular Regions of the Meniscus Have Enhanced Clonogenicity and Differentiation Potential Under Physioxia

The meniscus is composed of an avascular inner region and vascular outer region. The vascular region has been shown to contain a progenitor population with multilineage differentiation capacity. Strategies facilitating the isolation and propagation of these progenitors can be used to develop cell-based meniscal therapies. Differential adhesion to fibronectin has been used to isolate progenitor populations from cartilage, while low oxygen or physioxia (2% oxygen) enhances the meniscal phenotype. This study aimed to isolate progenitor populations from the avascular and vascular meniscus using differential fibronectin adherence and examine their clonogenicity and differentiation potential under hyperoxia (20% oxygen) and physioxia (2% oxygen). Human vascular and avascular meniscus cells were seeded onto fibronectin-coated dishes for a short period and monitored for colony formation under either hyperoxia or physioxia. Non-fibronectin adherent meniscus cells were also expanded under both oxygen tension. Individual fibronectin adherent colonies were isolated and further expanded, until approximately ten population doublings (passage 3), whereby they underwent chondrogenic, osteogenic, and adipogenic differentiation. Physioxia enhances clonogenicity of vascular and avascular meniscus cells on plastic or fibronectin-coated plates. Combined differential fibronectin adhesion and physioxia isolated a progenitor population from both meniscus regions with trilineage differentiation potential compared to equivalent hyperoxia progenitors. Physioxia isolated progenitors had a significantly enhanced meniscus matrix content without the presence of collagen X. These results demonstrate that combined physioxia and fibronectin adherence can isolate and propagate a meniscus progenitor population that can potentially be used to treat meniscal tears or defects.