Comparison of Clinical Efficacy Between Arthroscopically Assisted Gracilis Autograft With Suture Reinforcement Technique and Transtibial Pull-out Technique in Treating Medial Meniscus Posterior Root Tears

Background: To compare the short-term efficacy of the transtibial pull-out technique and gracilis autograft with suture reinforcement technique in the treatment of medial meniscus posterior root tears. Methods: A total of 64 patients with medial meniscus posterior root tears received reconstruction of the posterior root of the meniscus attachment point through the tibial tunnel between June 2018 and April 2019 were included in this study, patients were divided into 2 groups (transtibial pull-out technique group: 35 cases; gracilis autograft with suture reinforcement technique group: 29 cases) according to the different posterior meniscus root tear repair methods. Clinical outcomes were evaluated by the visual analogue scale (VAS) and Lysholm score and IKDC score, and the demographics and functional recovery of the knee were compared between the two groups.Results: Intraoperative and postsurgical complications such as infection were not found in the two groups, and there was a statistically significant improvement in the Lysholm score，IKDC score and VAS score (P<0.001; respectively). All the patients were very satisfied with the function of their knee at the last follow-up. However, compared with the transtibial pull-out repair group, the reinforced medial meniscal root reconstruction technique with gracilis autograft group were significant improvement in the meniscus healing rates and Lysholm score, IKDC score and VAS score at the end of follow-up (P<0.05; respectively).Conclusions: Compared with the transtibial pull-out technique, the reinforced medial meniscal root reconstruction technique with gracilis autograft is advantageous for treating these patients because it is a minimally invasive procedure with superior clinical outcome and meniscus healing rates.Levels of Evidence: Ⅲ, Case-control study Retrospective comparative study

Characterization of Macroporous Polycaprolactone/Silk Fibroin/Gelatin/Ascorbic Acid Composite Scaffolds and In Vivo Results in a Rabbit Model for Meniscus Cartilage Repair

Objective Meniscus injuries in the inner avascular zone have weak intrinsic self-healing capacity and often progress to osteoarthritis. This study focused on evaluating the effects of polycaprolactone/silk fibroin/gelatin/ascorbic acid (PCL/SF/Gel/AA) composite scaffolds seeded with adipose-derived mesenchymal stem cells (ASCs), in the meniscus repair. Design To this end, composite scaffolds were cross-linked using N-hydroxysuccinimide and 1-ethyl-3-(3-dimethyl-aminopropyl)-1-carbodiimide hydrochloride. Scaffolds were then characterized by scanning electron microscope, mechanical tests, total antioxidant capacity, swelling, and toxicity tests. Results The PCL/SF/Gel/AA scaffolds exhibited suitable mechanical properties. Furthermore, vitamin C rendered them the highest antioxidant capacity. The PCL/SF/Gel/AA scaffolds also showed good biocompatibility and proliferation for chondrocytes. Moreover, the PCL/SF/Gel/AA scaffold seeded with allogeneic ASCs was engrafted in New Zealand rabbits who underwent unilateral punch defect in the medial meniscus of the right knee. After 2 months postimplantation, macroscopic and histologic studies for new meniscus cartilage were performed. Conclusions Our results indicated that the PCL/SF/Gel/AA composite scaffolds seeded with allogeneic ASCs could successfully improve meniscus healing in damaged rabbits.

Repair of a Complete Radial Tear of the Lateral Meniscus

Background: Recognizing and repairing a lateral meniscus complete radial tear is critical, as this tear pattern makes the meniscus nonfunctional for load sharing of axial forces, and the convex shape of the lateral tibial plateau increases contact pressure. Indications: The diagnosis of a lateral meniscus complete radial tear was supported by joint effusion, lateral joint line tenderness, positive McMurray test, and magnetic resonance imaging findings. Arthroscopy confirmed the complete radial tear. Technique Description: During the procedure, a self-capturing suture passer was used to pass a size 0 high-strength suture through the meniscus. To start the repair, the free ends of the suture were passed from top to bottom on both sides of the tear. These free ends were then crossed on the bottom of the meniscus to create an X configuration and passed from the bottom to top slightly further back from the first suture passes. A spinal needle and a chia were used from outside-in to create a side-to-side suture across the tear to reinforce the repair, and a knot was then tied on the outer capsule. The chia was used once again to shuttle the size 0 sutures to the exterior portion of the knee and the knots were tied on top of the capsule. Results: Postoperatively, patients are 25% weightbearing with a 0° to 90° range of motion restriction for 6 weeks, with no deep squatting for 3 months. With an isolated radial tear repair, the patient can expect to return to sport by 5 months. Radial tear repair outcomes demonstrate reduced lateral meniscus extrusion, complete meniscus healing in 86.4% of patients, and significantly improved International Knee Documentation Committee, Lysholm, and Tegner scores. Discussion/Conclusion: Repairing a complete radial tear of the lateral meniscus restores the function of the meniscus. This surgical technique provides a high rate of complete meniscus healing and excellent patient satisfaction.

Intra-Articular Injection of Stromal Cell-Derived Factor 1α Promotes Meniscal Healing via Macrophage and Mesenchymal Stem Cell Accumulation in a Rat Meniscal Defect Model

The stromal-cell-derived factor-1α (SDF-1) is well-known for playing important roles in the regeneration of tissue by enhancing cell migration. However, the effect of SDF-1 in meniscal healing remains unknown. The purpose of this study is to investigate the effects of intra-articular injection of SDF-1 on meniscus healing in a rat meniscal defect model. The intra-articular SDF-1 injection was performed at meniscectomy and one week later. Macroscopic and histological assessments of the reparative meniscus were conducted at one, two and six weeks after meniscectomy in rats. In the macroscopic evaluation, the SDF-1 group showed an increase in the size of the reparative meniscus at six weeks after meniscectomy compared to the phosphate-buffered saline (PBS) injection (no-treatment) group. Histological findings showed that intra-articular injection of SDF-1 enhanced the migration of macrophages to the site of the regenerative meniscus at one and two weeks after meniscectomy. CD68- and CD163-positive cells in the SDF-1 group at one week after meniscectomy were significantly higher than in the no-treatment group. CD163-positive cells in the SDF-1 group at two weeks were significantly higher than in the no-treatment group. At one week after meniscectomy, there were cells expressing mesenchymal-stem-cell-related markers in the SDF-1 group. These results indicate the potential of regenerative healing of the meniscus by SDF-1 injection via macrophage and mesenchymal stem cell accumulation. In the present study, intra-articular administration of SDF-1 contributed to meniscal healing via macrophage, CD90-positive cell and CD105-positive cell accumulation in a rat meniscal defect model. The SDF-1–CXCR4 pathway plays an important role in the meniscal healing process. For potential clinical translation, SDF-1 injection therapy seems to be a promising approach for the biological augmentation in meniscal injury areas to enhance healing capacity.

MAGNETIC RESONANCE QUANTIFICATION OF MENISCUS VASCULARITY IN PEDIATRIC VERSUS ADULT KNEES

Background: Despite advances in surgical techniques, implant technology, and biological augmentation, one innate limitation to meniscus healing is lack of vascularity. Ability to quantify meniscal vascularity has been limited with previous techniques, and minimal data exists describing differential vascular zones in the skeletally immature meniscus. Purpose/Hypothesis: The objective of this study is to use quantitative contrast-enhanced magnetic resonance imaging (MRI) to compare meniscal vascularity in pediatric cadaveric specimens to adults. We hypothesize that the developing meniscus has greater and more uniform vascularity throughout all zones. Methods: We utilized 10 fresh-frozen human cadaveric knees (5 immature knees, age 0-6 months; 5 mature knees, age 34-67 years). Gadolinium-enhanced MRI was performed using a previously established vascularity quantification protocol. Regions of interest corresponding to peripheral and central zones of the meniscus were identified on pre-contrast coronal images, and signal enhancement (normalized against background tissue) was compared between pre-and post-contrast images (Figure 1). Results: Quantitative MRI demonstrated increased perfusion in the peripheral zones compared to the central zones (2.3:1 in immature knees and 3:1 in mature knees) in the medial and lateral menisci separately, and both menisci aggregated. Overall, the medial and lateral menisci had similar levels of perfusion in all specimens (45.9% ± 8.3% medial vs. 54.1% ± 8.3% lateral in immature knees; 50.5% ± 11.3% medial vs. 49.5% ± 11.3% lateral in mature knees). Immature specimens demonstrated greater overall normalized meniscal signal uptake, with the 0-month specimen demonstrating the greatest proportional signal enhancement. Conclusion: While blood flow to peripheral zones is greater than to central zones in both immature and adult menisci, younger menisci receive proportionally greater overall blood flow compared to adults, including greater blood flow to the inner zone, challenging the conventional wisdom of the central zone being avascular. As younger patients become increasingly active in sports, thorough understanding of the immature meniscus is required. Greater overall vascularity, including centrally, to the developing meniscus suggests improved healing potential following injury, and further encourages meniscal preservation when possible. [Figure: see text][Figure: see text]

A novel full-reduced HMGB1 and kartogenin-containing bio-active scaffold for meniscus regeneration

A novel bio-active scaffold for enhancing wounded meniscus healing has been developed by combination of High mobility group box 1 protein (HMGB1) and kartogenin (KGN) with alginate gel. The properties of the bio-active scaffold were also investigated using an in vitro cell culture model and in vivo rat wounded meniscus healing model. This HMGB1-KGN-containing bioactive scaffold released HMGB1 and KGN into wound area and kept high concentrations of HMGB1 and KGN in the system for more than two weeks. This HMGB1-KGN-containing bioactive scaffold also activated rat bone marrow stem cells (BMSCs) from G0 to GAlert stage and promoted cell proliferation as evidenced by 5-bromo-2-deoxyuridine (BrdU) incorporation testing. Our results also demonstrated that the HMGB1-KGN-containing bioactive scaffold induced cell migration in vitro and recruited the cells to wound area to promote wounded rat meniscus healing in vivo.

Biological augmentation to promote meniscus repair: from basic science to clinic application—state of the art

Meniscus tears range from acute tears during physical activity to chronic degenerative tears. The role of the meniscus in knee stability, load distribution, knee proprioception and arthritis prevention has been well established, and successful repair of meniscus tears has better clinical outcomes and protection from increased degenerative changes. Advancements in surgical techniques have demonstrated meniscus repair is possible in tears previously deemed unsalvageable. In addition, the use of biological augmentation has improved rates of meniscal healing, and the use of biologics is an active area of investigation. In this article, we review current methods of biological augmentation to promote meniscus healing, including biological injections, concomitant procedures and biological membranes.

Meniscus-Derived Matrix Bioscaffolds: Effects of Concentration and Cross-Linking on Meniscus Cellular Responses and Tissue Repair

Meniscal injuries, particularly in the avascular zone, have a low propensity for healing and are associated with the development of osteoarthritis. Current meniscal repair techniques are limited to specific tear types and have significant risk for failure. In previous work, we demonstrated the ability of meniscus-derived matrix (MDM) scaffolds to augment the integration and repair of an in vitro meniscus defect. The objective of this study was to determine the effects of percent composition and dehydrothermal (DHT) or genipin cross-linking of MDM bioscaffolds on primary meniscus cellular responses and integrative meniscus repair. In all scaffolds, the porous microenvironment allowed for exogenous cell infiltration and proliferation, as well as endogenous meniscus cell migration. The genipin cross-linked scaffolds promoted extracellular matrix (ECM) deposition and/or retention. The shear strength of integrative meniscus repair was improved with increasing percentages of MDM and genipin cross-linking. Overall, the 16% genipin cross-linked scaffolds were most effective at enhancing integrative meniscus repair. The ability of the genipin cross-linked scaffolds to attract endogenous meniscus cells, promote glycosaminoglycan and collagen deposition, and enhance integrative meniscus repair reveals that these MDM scaffolds are promising tools to augment meniscus healing.