Diagnostic accuracy of point-of-care knee ultrasound for evaluation of meniscus and collateral ligaments pathology in comparison with MRI.

BACKGROUND: Although magnetic resonance imaging (MRI) is often the "gold standard" for diagnosing knee problems, it has many limitations. Therefore, ultrasonography has been suggested as an effective rapid alternative in many knee abnormalities, especially after injuries of the meniscus and collateral ligaments. PURPOSE: To determine the diagnostic accuracy of point-of-care ultrasound (POCUS) in detecting injuries of the meniscus and collateral ligament compared to MRI. MATERIAL AND METHODS: An observational cross-sectional blinded study was conducted of 60 patients with clinically suspicious meniscus and collateral ligament injuries who were planned for an arthroscopy and or operative procedure. These patients underwent both blinded POCUS and MRI of the knees before the intervention procedure and results of both imaging modalities were compared according to the operative and arthroscopic findings. RESULTS: The preoperative reliability of POCUS compared to MRI for the assessment of meniscus injuries was sensitivity (92.9% vs. 90.5%), specificity (88.9% vs. 83.3%), positive predictive value (PPV; 95.1% vs. 92.7%), negative predictive value (NPV; 84.2% vs. 79%), and overall accuracy (91.7% vs. 88.3%). However, for diagnosing collateral ligament injures, POCUS versus MRI assessed sensitivity (92.3% vs. 88.5%), specificity (100% vs. 97.1%), PPV (100% vs. 95.8%), NPV (94.4% vs. 91.7%), and overall accuracy (96.7% vs. 93.3%). CONCLUSION: Ultrasonography is a useful screening tool for the initial diagnosis of meniscal and collateral ligament pathology compared to or even with potential advantages over MRI, especially when MRI is unavailable or contraindicated. As newly advanced portable ultrasonography becomes available, it could be considered as a point-of-injury diagnostic modality.

Acute changes in knee cartilage and meniscus following long-distance running in habituate runners: a systematic review on studies using quantitative magnetic resonance imaging.

OBJECTIVE: Running is among the most popular recreational activities; nonetheless, the acute post-race changes of cartilage or meniscus have rarely been determined. The current study aimed to review the acute changes in knee cartilage and meniscus among habituate runners following long-distance running detected by using quantitative magnetic resonance imaging (MRI). MATERIALS AND METHODS: Systematic literature search was performed on those dominate clinical databases which including MEDLINE, Cochrane, Embase, ScienceDirect, and Web of Science. Included studies should be conducted on healthy marathon runners, and the participants should be examined before and after running by using MRI. Intervention studies were excluded. RESULTS: A total number of 14 studies were finally included in this review which all examined the cartilage or meniscus by using MRI functional sequences. Among them, six studies quantitatively measured the changes regarding volume of the knee cartilage or/and meniscus. Five studies found that the volume would decrease initially after running. Ten studies reported T2 (T2*) would decrease after running and returned to the baseline in a short term, while T1ρ may remain increased in months. Five studies measured subareas for T2 (T2*) value, and found that the superficial and medial subarea changed more vastly than other regions after running. CONCLUSION: Runners experience transient changes in the volume and signals of knee cartilage and meniscus after long-distance running. A liquid exchange and material interaction in cartilage and meniscus was observed after running. Superficial and medial areas of knee cartilage and meniscus might be more susceptible to mechanical loading.

SDF-1 preconditioned HPC scaffolds mobilize cartilage-derived progenitors and stimulate meniscal fibrocartilage repair in human explant tissue culture.

Purpose: The purpose of this study was to characterize the influence of SDF-1 on cell migration/adhesion and temporal gene expression of human cartilage mesenchymal progenitor cells (C-PCs); and to utilize SDF-1 conditioned mesenchymal progenitors to stimulate reintegration of human meniscus fibrocartilage breaks.Materials and Methods: Characterization of SDF-1-induced cell migration was achieved using hydroxypropyl cellulose (HPC) scaffolds pretreated with SDF-1. Fluorescence microscopy and cell counting were used to visualize and quantify the extent of cell migration into scaffolds, respectively. Relative mRNA expression analysis was used to characterize the temporal effects of SDF-1 on C-PCs. Tissue reintegration experiments were conducted using cylindrical human meniscal tissue punches, which were then placed back together with an HPC scaffold embedded with C-PCs. Tensile testing was used to evaluate the extent of tissue reintegration stimulated by human mesenchymal progenitors.Results: C-PCs migrate into scaffolds in response to SDF-1 with the same efficiency as mesenchymal progenitors from human marrow (BM-MSCs). SDF-1 treatment of C-PCs did not significantly alter the expression of early and late stage chondrogenic differentiation genes. Scaffolds containing SDF-1 pre-conditioned C-PCs successfully adhered to fibrocartilage breaks and migrated from the scaffold into the tissue. Tensile testing demonstrated that SDF-1 preconditioned C-PCs stimulate reintegration of fibrocartilage tears.Conclusion: C-PCs migrate in response to SDF-1. Exposure to SDF-1 does not significantly alter the unique mRNA profile of C-PCs that make them desirable for cartilaginous tissue repair applications. SDF-1 pretreated mesenchymal progenitors successfully disperse into injured tissues to help facilitate tissue reintegration.

Human Knee Meniscus Regeneration Strategies: a Review on Recent Advances.

PURPOSE OF REVIEW: Lack of vascularity in the human knee meniscus often leads to surgical removal (total or partial meniscectomy) in the case of severe meniscal damage. However, complete recovery is in question after such removal as the meniscus plays an important role in knee stability. Thus, meniscus tissue regeneration strategies are of intense research interest in recent years. RECENT FINDINGS: The structural complexity and inhomogeneity of the meniscus have been addressed with processing technologies for precisely controlled three dimensional (3D) complex porous scaffold architectures, the use of biomolecules and nanomaterials. The regeneration and replacement of the total meniscus have been studied by the orthopedic and scientific communities via successful pre-clinical trials towards mimicking the biomechanical properties of the human knee meniscus. Researchers have attempted different regeneration strategies which contribute to in vitro regeneration and are capable of repairing meniscal tears to some extent. This review discusses the present state of the art of these meniscus tissue engineering aspects.

Viable Vitreous Grafts of Whole Porcine Menisci for Transplant in the Knee and Temporomandibular Joints.

The shortage of suitable donor meniscus grafts from the knee and temporomandibular joint (TMJ) impedes treatments for millions of patients. Vitrification offers a promising solution by transitioning these tissues into a vitreous state at cryogenic temperatures, protecting them from ice crystal damage using high concentrations of cryoprotectant agents (CPAs). However, vitrification's success is hindered for larger tissues (>3 mL) due to challenges in CPA penetration. Dense avascular meniscus tissues require extended CPA exposure for adequate penetration; however, prolonged exposure becomes cytotoxic. Balancing penetration and reducing cell toxicity is required. To overcome this hurdle, a simulation-based optimization approach is developed by combining computational modeling with microcomputed tomography (µCT) imaging to predict 3D CPA distributions within tissues over time accurately. This approach minimizes CPA exposure time, resulting in 85% viability in 4-mL meniscal specimens, 70% in 10-mL whole knee menisci, and 85% in 15-mL whole TMJ menisci (i.e., TMJ disc) post-vitrification, outperforming slow-freezing methods (20%-40%), in a pig model. The extracellular matrix (ECM) structure and biomechanical strength of vitreous tissues remain largely intact. Vitreous meniscus grafts demonstrate clinical-level viability (≥70%), closely resembling the material properties of native tissues, with long-term availability for transplantation. The enhanced vitrification technology opens new possibilities for other avascular grafts.

Biomechanical Comparison of All-Suture, All-Inside Meniscus Repair Devices in a Human Cadaveric Meniscus Model.

OBJECTIVE: Newer all-suture, all-inside meniscus repair devices utilize soft suture anchors. The purpose of this study was to compare the biomechanical performance of 4 meniscus repair devices in human cadaver menisci: the JuggerStitch (all-suture, all-inside), the FiberStitch (all-suture, all-inside), a polyether ether ketone (PEEK) all-inside, and an inside-out device. DESIGN: Forty human cadaver menisci were tested after creating 20 mm longitudinal tears in the posterior meniscus. Each knee was randomized to 1 of 4 meniscus repair groups: JuggerStitch (all-suture, all-inside), FiberStitch (all-suture, all-inside), FAST-FIX 360 (PEEK-based anchor all-inside), and inside-out (with BroadbandTM tape meniscus needles). For each meniscus, 2 devices were used to prepare vertical mattress repair construct. The specimens were tested by pre-conditioning 20 cycles between 5 N and 30 N and then the tear diastasis was measured, followed by distraction to failure phase after imposing a displacement at a rate of 0.5 mm/s. RESULTS: Ten menisci were tested in each of the 4 groups. After pre-conditioning, there was no significant difference in the gap formation among groups (P = 0.212). The average failure load for the JuggerStitch, FiberStitch, PEEK all-inside, and inside-out was 384 N, 311 N, 207 N, and 261 N, respectively, with a significant difference between groups (P = 0.034). Post hoc analysis showed the JuggerStitch failure load was higher than the PEEK all-inside and inside-out (P = 0.005, and P = 0.045, respectively). There was no significant difference between the failure load of the JuggerStitch and FiberStitch (P = 0.225). CONCLUSION: The JuggerStitch all-suture device, FiberStitch all-suture device, PEEK all-inside, and inside-out devices have similar biomechanical properties for gapping and stiffness. The JuggerStitch all-suture, all-inside device has superior failure load compared with the PEEK all-inside and inside-out repair for longitudinal meniscus tear repair.

Prognostic Factors on Preoperative MRI for Patient-Reported Outcomes After Posterior Medial Meniscus Root Repair.

Background: Repair of posterior medial meniscus root (PMMR) tears has demonstrated favorable outcomes and may prevent rapid progression of knee osteoarthritis; however, there is a paucity of data regarding prognostic factors affecting postoperative outcomes. Purpose/Hypothesis: The purpose of this study was to identify factors on preoperative magnetic resonance imaging (MRI) that predict postoperative outcomes after PMMR repair. It was hypothesized that patients with increasing levels of degenerative changes as evaluated through semiquantitative preoperative MRI scans would have worse postoperative patient-reported outcome (PRO) scores. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent PMMR repair between 2012 and 2020 and had minimum 2-year follow-up data were enrolled. Pre- and postoperative visual analog scale pain scores and postoperative PRO surveys including the Patient-Reported Outcomes Measurement Information System-Physical Function, Lysholm knee score, and Knee injury and Osteoarthritis Outcome Score (KOOS) were collected. Patients who achieved the Patient Acceptable Symptom State (PASS) on the KOOS subscales were reported. Two fellowship-trained musculoskeletal radiologists reviewed preoperative MRIs and calculated the Whole-Organ Magnetic Resonance Imaging Score for meniscus, cartilage, bone marrow edema-like lesions (BMELL), and meniscal extrusion. Statistical analysis was performed using the 2-sample t test, Mann-Whitney test, and Fisher exact test for categorical variables. Results: A total of 29 knees in 29 patients were evaluated (22 female, 7 male; mean age at surgery, 52.3 ± 9.9 years; body mass index, 27.6 ± 5.6 kg/m2; mean follow-up, 59.6 ± 26.5 months). Visual analog scale for pain scores decreased significantly from preoperatively (4.9 ± 2.0) to final follow-up (1.6 ± 1.9) (P < .001), and the percentage of patients meeting the PASS ranged from 44.8% for KOOS Sport and Recreation to 72.4% for KOOS Pain and KOOS Quality of Life. Patients with medial tibial BMELL (MT-BMELL) had significantly lower KOOS Symptoms scores (76.1 ± 17.3 vs 88.4 ± 9.7 without MT-BMELL; P = .032). Cartilage quality and presence of meniscal extrusion were not associated with outcomes. Conclusion: Patients with MT-BMELL on their preoperative MRI in the setting of PMMR tear were found to have worse KOOS Symptoms scores after PMMR repair.

Current advances in engineering meniscal tissues: insights into 3D printing, injectable hydrogels and physical stimulation based strategies.

The knee meniscus is the cushioning fibro-cartilage tissue present in between the femoral condyles and tibial plateau of the knee joint. It is largely avascular in nature and suffers from a wide range of tears and injuries caused by accidents, trauma, active lifestyle of the populace and old age of individuals. Healing of the meniscus is especially difficult due to its avascularity and hence requires invasive arthroscopic approaches such as surgical resection, suturing or implantation. Though various tissue engineering approaches are proposed for the treatment of meniscus tears, three-dimensional (3D) printing/bioprinting, injectable hydrogels and physical stimulation involving modalities are gaining forefront in the past decade. A plethora of new printing approaches such as direct light photopolymerization and volumetric printing, injectable biomaterials loaded with growth factors and physical stimulation such as low-intensity ultrasound approaches are being added to the treatment portfolio along with the contemporary tear mitigation measures. This review discusses on the necessary design considerations, approaches for 3D modeling and design practices for meniscal tear treatments within the scope of tissue engineering and regeneration. Also, the suitable materials, cell sources, growth factors, fixation and lubrication strategies, mechanical stimulation approaches, 3D printing strategies and injectable hydrogels for meniscal tear management have been elaborated. We have also summarized potential technologies and the potential framework that could be the herald of the future of meniscus tissue engineering and repair approaches.

Predictors of Long-term Patient-Reported Outcome Measures After Collagen Meniscal Implant for Partial Meniscal Defects.

Background: Collagen meniscal implant (CMI) is considered an effective procedure for reducing knee pain and improving knee function after previous meniscectomy. Nevertheless, the current knowledge regarding long-term patient reported-outcome measures after CMI is limited. Purpose: To evaluate clinical outcomes, reoperations, and failures of CMI at a minimum 10-year follow-up. Study Design: Case series; Level of evidence, 4. Methods: Consecutive patients who underwent CMI at a single institution were screened for eligibility. Inclusion criteria for the present study were (1) medial or lateral CMI; (2) isolated or combined procedure with anterior cruciate ligament reconstruction, knee osteotomy, or cartilage treatment; and (3) follow-up between 10 and 15 years. Demographics and surgical details were obtained via chart review. Patients were asked if they were satisfied with the procedure and were evaluated with the Lysholm score, Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale for pain, and Tegner score at the final follow-up. Cases requiring partial or total scaffold removal for any reason (including scaffold breakage, infection, or surgery for osteoarthritis progression) were considered surgical failure. Survival analysis was performed with Kaplan-Meier curve, and clinical scores were analyzed based on the Patient Acceptable Symptom State (PASS). Results: A total of 92 patients (mean age, 42.2 years were included in the analysis. A significant improvement in all clinical scores was reported between the preoperative evaluation and the last follow-up. A chondropathy with Outerbridge grade ≥3 was associated with significantly overall lower clinical scores, while a timing from meniscectomy to CMI of ≥5 years determined more pain at rest and reduced Quality of Life in the KOOS subscale. No significant difference was found in terms of clinical scores between patients undergoing isolated and combined procedures. At the final follow-up, the mean Lysholm score was 76.3 points. In total, 12 cases (13%) were considered surgical failures. Sixteen patients (17%) did not reach PASS for the Lysholm score, with a total of 28 cases (30%) classified as clinical failures. Overall, 19% (KOOS Pain) and 40% (KOOS Symptoms) of patients did not achieve the PASS in the KOOS subscales. Chondropathy with Outerbridge grade ≥3 was associated with a higher risk of not achieving the PASS in all the KOOS subscales, while age at surgery of ≥45 years resulted in a lower risk of not achieving PASS in the Pain subscale. At the last follow-up, 63% of patients were still involved in sports activity, with 41% at the same or higher level. Finally, 80% of the patients were satisfied with the procedure. Conclusion: Up to 10 years after surgery, around 70% of the patients who underwent CMI reported satisfactory clinical results, with clinical subjective scores still higher compared with the preoperative evaluation. Overall, 30% of cases were considered clinical failures, with 13% considered surgical failures and 17% not meeting the PASS for the Lysholm score. In addition, cartilage status and time from meniscectomy were shown to have a negative impact on the outcomes, while an age ≥45 years was associated with less pain. There was no clinical difference between patients who underwent isolated CMI or combined procedures.

Influence of cartilage and menisci on the sagittal slope of the tibial plateaus.

We analyzed the magnetic resonance studies of the knee in 80 subjects, 45 men and 35 women with a mean age of 38.9 years, who showed no pathological condition of the joint. Using an imaging visualization software, the sagittal longitudinal axis of the tibia was identified. The angle between this axis and a line tangent to the bone profile of the tibial plateau (bone slope) and to the superior border of the menisci (meniscal slope) were calculated. Thickness of anterior and posterior portion of menisci and underlying cartilage were also measured. The bone slope averaged 8° and 7.7° on the medial and lateral sides, respectively. The mean meniscal slope was 4.1° and 3.3° on the medial and lateral sides, respectively, with a significant difference compared with the bone slope. Menisci and underlying cartilage were significantly thicker in their posterior than their anterior portion (7.6 and 5.2 mm, respectively, in the medial compartment; 8.6 and 5.2 mm, respectively, in the lateral compartment). The presence of cartilage and menisci implies a significant decrease in the posterior tibial slope. In the lateral compartment, the greater the bone slope, the larger the difference between bone and meniscal slope, which means that a marked posterior tilt of the lateral tibial plateau is decreased by the cartilage and meniscus. These findings should be taken into account in planning surgical procedures which affect the slope of the articular tibial surface.

Advanced bioactive glue tethering Lubricin/PRG4 to promote integrated healing of avascular meniscus tears.

Meniscus injuries are extremely common with approximately one million patients undergoing surgical treatment annually in the U.S. alone, but no regenerative therapy exist. Previously, we showed that controlled applications of connective tissue growth factor (CTGF) and transforming growth factor beta 3 (TGFß3) via fibrin-based bio-glue facilitate meniscus healing by inducing recruitment and stepwise differentiation of synovial mesenchymal stem/progenitor cells. Here, we first explored the potential of genipin, a natural crosslinker, to enhance fibrin-based glue's mechanical and degradation properties. In parallel, we identified the harmful effects of lubricin on meniscus healing and investigated the mechanism of lubricin deposition on the injured meniscus surface. We found that the pre-deposition of hyaluronic acid (HA) on the torn meniscus surface mediates lubricin deposition. Then we implemented chemical modifications with heparin conjugation and CD44 on our bioactive glue to achieve strong initial bonding and integration of lubricin pre-coated meniscal tissues. Our data suggested that heparin conjugation significantly enhances lubricin-coated meniscal tissues. Similarly, CD44, exhibiting a strong binding affinity to lubricin and hyaluronic acid (HA), further improved the integrated healing of HA/lubricin pre-coated meniscus injuries. These findings may represent an important foundation for developing a translational bio-active glue guiding the regenerative healing of meniscus injuries.

A Comparison of All-inside and Inside-out Meniscal Repair in Elite Athletes.

BACKGROUND: The popularization of all-inside (AI) meniscal repair devices has led to a shift away from the historical gold standard of inside-out (IO) meniscal repair without comparative studies to support the change. PURPOSE: To compare the failure rate and time to failure of AI and IO meniscal repair performed in elite athletes. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective review was performed of all professional and national- and international-level amateur athletes who underwent meniscal repair, with a minimum of 2-year follow-up between January 2013 and September 2019. Meniscal repair was classified as AI or IO depending on the surgical technique performed. Treatment failure was defined as patients having to undergo subsequent surgery to address a persistent meniscal tear after repair. Cox proportional hazards modeling was used to determine if meniscal repair failure rates differed by the location and technique of meniscal repair. Models were controlled for known risk factors such as age, sex, sport, and concurrent cruciate ligament reconstruction. RESULTS: A total of 192 (135 lateral and 57 medial) meniscal repairs were performed in elite athletes during the study period. Overall, 41 (21%) meniscal repairs met the criteria for failure. Medial meniscal tears repaired with the AI technique failed at a significantly higher rate (18/31 [58%]) than medial meniscal tears repaired with the IO technique (6/26 [23%]) or lateral meniscal tears repaired with the AI (9/76 [12%]) or IO (8/59 [14%]) technique (P < .001). Cox proportional hazards modeling revealed that a medial meniscal tear repaired with the AI technique had an almost 8 times greater hazard of failure than a lateral meniscal tear repaired with the AI technique (P < .001). At 1 year postoperatively, 8% of lateral meniscal repairs had failed (regardless of technique), while medial meniscal tears failed at a rate of 16% with the IO technique and 42% with the AI technique. By 2 years, 53% of medial meniscal tears repaired with the AI technique had failed, and by 5 years, 63% had failed. CONCLUSION: AI repair of medial meniscal tears led to a higher rate of failure than IO repair of medial or lateral meniscal tears in elite athletes. Medial meniscal repair failed at a higher rate than lateral meniscal repair.

Clinical efficacy of platelet-rich plasma combined with arthroscopic meniscal plasty on pain, function and physiologic indicators in elderly patients with knee meniscus injury: a retrospective observational study.

OBJECTIVE: To explore the clinical efficacy of platelet-rich plasma (PRP) combined with arthroscopic meniscal plasty on meniscus injury of the knee joint in the elderly. METHODS: Fifty-six elderly patients with meniscus injuries were evaluated, including 28 patients who underwent arthroscopic meniscal repair and 28 patients who underwent arthroscopic meniscus repair combined with PRP injection. Primary outcomes included visual analogue scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lysholm score, Lequesne index, Range of motion (ROM), and secondary outcomes included bone gla-protein (BGP), insulin-like growth factor-1 (IGF-1), and matrix metalloproteinase-1 (MMP-1). The primary and secondary measurement outcomes were assessed for each patient before and after the 12 weeks of treatment. RESULTS: The VAS, WOMAC, Lysholm, Lequesne, and ROM were more improved in the PRP group compared to the control group (all P < 0.05). BGP, IGF-1, and MMP-1 were more reduced in the PRP group compared to the control group (all P < 0.05). CONCLUSION: The treatments of PRP combined with arthroscopic meniscal plasty can significantly improve the pain, function, and physiologicindicators in elderly patients.

Yucatan Minipig Knee Meniscus Regional Biomechanics and Biochemical Structure Support its Suitability as a Large Animal Model for Translational Research.

Knee meniscus injuries are the most frequent causes of orthopedic surgical procedures in the U.S., motivating tissue engineering attempts and the need for suitable animal models. Despite extensive use in cardiovascular research and the existence of characterization data for the menisci of farm pigs, the farm pig may not be a desirable preclinical model for the meniscus due to rapid weight gain. Minipigs are conducive to in vivo experiments due to their slower growth rate than farm pigs and similarity in weight to humans. However, characterization of minipig knee menisci is lacking. The objective of this study was to extensively characterize structural and functional properties within different regions of both medial and lateral Yucatan minipig knee menisci to inform this model's suitability as a preclinical model for meniscal therapies. Menisci measured 23.2-24.8 mm in anteroposterior length (33-40 mm for human), 7.7-11.4 mm in width (8.3-14.8 mm for human), and 6.4-8.4 mm in peripheral height (5-7 mm for human). Per wet weight, biochemical evaluation revealed 23.9-31.3% collagen (COL; 22% for human) and 1.20-2.57% glycosaminoglycans (GAG; 0.8% for human). Also, per dry weight, pyridinoline crosslinks (PYR) were 0.12-0.16% (0.12% for human) and, when normalized to collagen content, reached as high as 1.45-1.96 ng/µg. Biomechanical testing revealed circumferential Young's modulus of 78.4-116.2 MPa (100-300 MPa for human), circumferential ultimate tensile strength (UTS) of 18.2-25.9 MPa (12-18 MPa for human), radial Young's modulus of 2.5-10.9 MPa (10-30 MPa for human), radial UTS of 2.5-4.2 MPa (1-4 MPa for human), aggregate modulus of 157-287 kPa (100-150 kPa for human), and shear modulus of 91-147 kPa (120 kPa for human). Anisotropy indices ranged from 11.2-49.4 and 6.3-11.2 for tensile stiffness and strength (approximately 10 for human), respectively. Regional differences in mechanical and biochemical properties within the minipig medial meniscus were observed; specifically, GAG, PYR, PYR/COL, radial stiffness, and Young's modulus anisotropy varied by region. The posterior region of the medial meniscus exhibited the lowest radial stiffness, which is also seen in humans and corresponds to the most prevalent location for meniscal lesions. Overall, similarities between minipig and human menisci support the use of minipigs for meniscus translational research.

The Functionally Grading Elastic and Viscoelastic Properties of the Body Region of the Knee Meniscus.

The knee meniscus is a highly porous structure which exhibits a grading architecture through the depth of the tissue. The superficial layers on both femoral and tibial sides are constituted by a fine mesh of randomly distributed collagen fibers while the internal layer is constituted by a network of collagen channels of a mean size of 22.14 [Formula: see text]m aligned at a [Formula: see text] inclination with respect to the vertical. Horizontal dog-bone samples extracted from different depths of the tissue were mechanically tested in uniaxial tension to examine the variation of elastic and viscoelastic properties across the meniscus. The tests show that a random alignment of the collagen fibers in the superficial layers leads to stiffer mechanical responses (E = 105 and 189 MPa) in comparison to the internal regions (E = 34 MPa). All regions exhibit two modes of relaxation at a constant strain ([Formula: see text] to 7.7 s, [Formula: see text] = 49.9 to 59.7 s).

Forces at the Anterior Meniscus Attachments Strongly Increase Under Dynamic Knee Joint Loading.

BACKGROUND: The anatomic appearance and biomechanical and clinical importance of the anterior meniscus roots are well described. However, little is known about the loads that act on these attachment structures under physiological joint loads and movements. HYPOTHESES: As compared with uniaxial loading conditions under static knee flexion angles or at very low flexion-extension speeds, more realistic continuous movement simulations in combination with physiological muscle force simulations lead to significantly higher anterior meniscus attachment forces. This increase is even more pronounced in combination with a longitudinal meniscal tear or after total medial meniscectomy. STUDY DESIGN: Controlled laboratory study. METHODS: A validated Oxford Rig-like knee simulator was used to perform a slow squat, a fast squat, and jump landing maneuvers on 9 cadaveric human knee joints, with and without muscle force simulation. The strains in the anterior medial and lateral meniscal periphery and the respective attachments were determined in 3 states: intact meniscus, medial longitudinal tear, and total medial meniscectomy. To determine the attachment forces, a subsequent in situ tensile test was performed. RESULTS: Muscle force simulation resulted in a significant strain increase at the anterior meniscus attachments of up to 308% (P < .038) and the anterior meniscal periphery of up to 276%. This corresponded to significantly increased forces (P < .038) acting in the anteromedial attachment with a maximum force of 140 N, as determined during the jump landing simulation. Meniscus attachment strains and forces were significantly influenced (P = .008) by the longitudinal tear and meniscectomy during the drop jump simulation. CONCLUSION: Medial and lateral anterior meniscus attachment strains and forces were significantly increased with physiological muscle force simulation, corroborating our hypothesis. Therefore, in vitro tests applying uniaxial loads combined with static knee flexion angles or very low flexion-extension speeds appear to underestimate meniscus attachment forces. CLINICAL RELEVANCE: The data of the present study might help to optimize the anchoring of meniscal allografts and artificial meniscal substitutes to the tibial plateau. Furthermore, this is the first in vitro study to indicate reasonable minimum stability requirements regarding the reattachment of torn anterior meniscus roots.

Engineering self-assembled neomenisci through combination of matrix augmentation and directional remodeling.

Knee meniscus injury is frequent, resulting in over 1 million surgeries annually in the United States and Europe. Because of the near-avascularity of this fibrocartilaginous tissue and its intrinsic lack of healing, tissue engineering has been proposed as a solution for meniscus repair and replacement. This study describes an approach employing bioactive stimuli to enhance both extracellular matrix content and organization of neomenisci toward augmenting their mechanical properties. Self-assembled fibrocartilages were treated with TGF-ß1, chondroitinase ABC, and lysyl oxidase-like 2 (collectively termed TCL) in addition to lysophosphatidic acid (LPA). TCL + LPA treatment synergistically improved circumferential tensile stiffness and strength, significantly enhanced collagen and pyridinoline crosslink content per dry weight, and achieved tensile anisotropy (circumferential/radial) values of neomenisci close to 4. This study utilizes a combination of bioactive stimuli for use in tissue engineering studies, providing a promising path toward deploying these neomenisci as functional repair and replacement tissues. STATEMENT OF SIGNIFICANCE: This study utilizes a scaffold-free approach, which strays from the tissue engineering paradigm of using scaffolds with cells and bioactive factors to engineer neotissue. While self-assembled neomenisci have attained compressive properties akin to native tissue, tensile properties still require improvement before being able to deploy engineered neomenisci as functional tissue repair or replacement options. In order to augment tensile properties, this study utilized bioactive factors known to augment matrix content in combination with a soluble factor that enhances matrix organization and anisotropy via cell traction forces. Using a bioactive factor to enhance matrix organization mitigates the need for bioreactors used to apply mechanical stimuli or scaffolds to induce proper fiber alignment.

Prevalence of Asymptomatic Intra-articular Changes of the Knee in Adult Professional Soccer Players.

BACKGROUND: Currently, there are few data on the association between participation in soccer and the condition of the knee joints in adult professional players. HYPOTHESIS: A high percentage of professional soccer players will have asymptomatic intra-articular changes of the knee. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: The condition of the intra-articular structures (osteophytes, cartilage, and menisci) in 94 knee joints of 47 adult professional soccer players (mean ± SD age, 25.7 ± 4.6 years; body mass index, 22.8 ± 1.4 kg/m2) was analyzed. A 1.5-T magnetic resonance imaging scanner was used to perform the imaging, and the anonymized data were analyzed by 2 experienced radiologists. RESULTS: Cartilage of both knee joints was affected in 97.9% of soccer players. Meniscal lesions were detected in 97.8% of joints, affecting both joints in 93.6% of athletes. Grade 2 cartilage lesions were the most prevalent (36%-60% depending on the lesion site), and grade 4 lesions were detected in 12.7% of joints. The medial femoral condyle and medial tibial plateau were most frequently affected by cartilage lesions (85.1%). Among meniscal lesions, grade 2 lesions were the most prevalent, being detected in 71% of the cases. Grade 3 lesions were detected in 13.8% of the joints. The posterior horn of the lateral meniscus was the most common site of meniscal lesions (affected in 95.7% of the joints). Osteophytes were detected in 4.2% of joints. CONCLUSION: The prevalence of asymptomatic cartilage and meniscal lesions in the knees of adult professional soccer players is extremely high and is not associated with the reduction of sports involvement. This research should promote the correct interpretation of magnetic resonance imaging data obtained from soccer players with acute trauma and the reduction of the number of unwarranted surgical procedures.

Platelet-Rich Plasma Reduces Failure Risk for Isolated Meniscal Repairs but Provides No Benefit for Meniscal Repairs With Anterior Cruciate Ligament Reconstruction.

BACKGROUND: The effect of platelet-rich plasma (PRP) on the risk of meniscal repair failure is unclear. Current evidence is limited to small studies without comparison between isolated repairs and meniscal repairs with concomitant anterior cruciate ligament (ACL) reconstruction. It is also unclear whether the efficacy of PRP differs between preparation systems in the setting of meniscal repair. PURPOSE: (1) To determine whether intraoperative PRP affects the risk of meniscal repair failure. (2) To determine whether the effect of PRP on meniscal failure risk is influenced by ACL reconstruction status or by PRP preparation system. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The study entailed 550 patients (mean ± SD age, 28.8 ± 11.2 years) who underwent meniscal repair surgery with PRP (n = 203 total; n = 148 prepared with GPS III system, n = 55 prepared with Angel system) or without PRP (n = 347) and with (n = 399) or without (n = 151) concurrent ACL reconstruction. The patients were assessed for meniscal repair failure within 3 years. The independent effect of PRP on the risk of meniscal repair failure was determined by multivariate Cox proportional hazards modeling with adjustment for age, sex, body mass index, ACL status, tear pattern, tear vascularity, repair technique, side (medial or lateral), and number of sutures or implants used. RESULTS: Failures within 3 years occurred in 17.0% of patients without PRP and 14.6% of patients with PRP (P = .60) (Angel PRP, 15.9%; GPS III PRP, 14.2%; P = .58). Increased patient age was protective against meniscal failure regardless of ACL or PRP status (per 5-year increase in age: adjusted hazard ratio [aHR], 0.90; 95% CI, 0.81-1.0; P = .047). The effect of PRP on meniscal failure risk was dependent on concomitant ACL injury status. Among isolated meniscal repairs (20.3% failures at 3 years), PRP was independently associated with lower risk of failure (aHR, 0.18; 95% CI, 0.03-0.59; P = .002) with no difference between PRP preparation systems (P = .84). Among meniscal repairs with concomitant ACL reconstruction (14.1% failures at 3 years), PRP was not independently associated with risk of failure (aHR, 1.39; 95% CI, 0.81-2.36; P = .23) with no difference between PRP preparation systems (P = .78). CONCLUSION: Both PRP preparations used in the current study had a substantial protective effect in terms of the risk of isolated meniscal repair failure over 3 years. In the setting of concomitant ACL reconstruction, PRP does not reduce the risk of meniscal repair failure.

Changing MRI after subchondroplasty with partial meniscectomy for knee osteoarthritis.

A 54-year old woman with primary osteoarthritis and a tibial bone marrow lesion underwent subchondroplasty with injectable calcium phosphate. Post-operatively, the patient's symptoms worsened, and she lost the ability to bear weight. Follow-up MRI revealed previously absent, diffuse STIR hyperintensity in the tibia extending far beyond the surgical site. Twelve months post-operatively, symptoms spontaneously resolved. As the prevalence of subchondroplasty grows it will be important to recognize potential complications. To the authors' best knowledge this is the first report of significantly worsening pain and difficulty bearing weight corresponding with diffuse hyperintense T2 signal in the tibia after a calcium phosphate subchondroplasty.