Verdonk, Peter

Abstract Purpose The aim of this systematic review and meta‐analysis was to quantify and compare the evidence on the results obtained with the surgical treatments for meniscal lesions in athletes. Methods A literature search was conducted on PubMed, Cochrane and Web of Science in August 2025 according to the PRISMA guidelines. Inclusion criteria were clinical studies (randomised controlled trials [RCTs], non‐randomised comparative studies and case series), ≥6 patients, in the English language, on the surgical treatment of meniscal lesions in athletes. A meta‐analysis was conducted on the rate of patients returning to sport, the time to return to sport, and the rate of patients returning to the pre‐injury level of sport. Patient‐reported outcome measures, adverse events, failures and reoperation rates, as well as risk of bias and quality of evidence, were also documented. The risk of bias was assessed using the Cochrane RoB 2.0 tool, the Cochrane ROBINS‐I tool, and the JBI Critical appraisal checklist. The quality of evidence was assessed using a modified Coleman score and the GRADE tool. Result The mean time to return to sport was 2.1 months for meniscectomy, 5.8 months for meniscal repair, and 8.9 months for meniscal allograft transplantation (MAT). Statistically significant differences were observed between meniscectomy and repair and between meniscectomy and MAT (both p < 0.001). Meniscectomy showed a return to sport rate of 98.2%, meniscal repair of 96.9%, and MAT of 94.2%, while return to the same pre‐injury level of sport was reported as 84.4% for meniscectomy, 81.3% for meniscal repair, and 77.4% for MAT, with no statistically significant differences between groups. The mean modified Coleman Methodology Score for the included studies was 66.6 ± 7.0. Conclusion Meniscectomy, meniscal repair, and MAT are all able to provide high rates of return to sport in athletes. In the investigated treatment cohorts, meniscectomy presented the shortest pooled time to return to sport, followed by meniscal repair and MAT. Importantly, all treatments offered good rates of return to the same level of athletic performance. The treatment choice should be guided by an individualised, multidisciplinary approach aimed at providing a patient‐tailored treatment strategy to optimise both athletic recovery and joint preservation. Level of Evidence Level I.

Objective This proof-of-concept study investigated an improved cell-based injection therapy combining mesenchymal stem cells (MSCs) and meniscus cells (MCs) to support superior meniscus allograft repopulation and early revival compared to injecting MSCs alone. Design In this controlled laboratory study, frozen meniscus allograft samples were injected vertically with a cell suspension containing different ratios of MSCs and MCs or control (lactated ringers) and cultured for 28 days. Samples were analyzed weekly for cell viability, migration, and metabolism using histological and biochemical assays. Tissue medium was analyzed for matrix metalloproteinase (MMP) expression using zymography. Results Cellular repopulation of frozen allografts injected with different cell suspensions was validated by immunohistochemistry. Significant higher DNA content was evidenced in grafts treated with suspensions of MCs or MC:MSC (1:4 ratio). Cell metabolic activity was significantly different between all treated groups and control group after 1 week. Allografts injected with MCs showed significantly more cell proliferation than injections with MSCs. MMP2 activity was detected in medium of all grafts cellularized with MCs with or without MSCs. Scanning electron microscopy (SEM) analysis showed resolution of the needle puncture, but not in the control group. Cell labeling of MCs upon injection of mixed MC:MSC suspensions revealed a gradual increase in the cell ratio. Conclusions The findings of this study establish that injection of MCs with or without MSCs enhances the cellularity of meniscus allograft to support early graft revival and remodeling.

Background: Fresh-frozen allografts are the current standard in meniscal allograft transplant (MAT) surgery, due to their availability, ease of preservation, and affordability. However, fresh-frozen grafts are associated with several clinical challenges such as graft shrinkage and extrusion, among many others. Purpose: To present the current knowledge on the use of fresh meniscal allografts, presenting whether benefits associated with fresh grafts provide sufficient evidence to support their use in clinical practice. Study Design: Systematic review; Level of evidence, 5. Methods: A comprehensive search was conducted with keywords listed below. After an initial screening on title and abstract, full-text articles were assessed with the inclusion criteria. Results: A total of 78 studies matched the inclusion criteria. Literature and preclinical studies indicated that fresh meniscal allografts are beneficial for maintaining mechanical properties, graft ultrastructure, and matrix metabolism due to the presence of viable cells. Therefore, fresh allografts may address common complications associated with fresh-frozen MAT. To overcome challenges associated with both fresh-frozen and fresh allografts, a group has studied treating fresh-frozen allografts with a cell-based injection therapy. Conclusion: Fresh meniscal allografts pose several challenges including limited availability, demanding preservation procedures, and high costs. Although the role of viable cells within meniscal allografts remains controversial, these cells may be vital for maintaining tissue properties.

AbstractMeniscus allograft transplantations (MATs) represent established surgical procedures with proven outcomes. Yet, storage as frozen specimens and limited cellular repopulation may impair graft viability. This proof‐of‐concept study tests the feasibility of injecting allogeneic mesenchymal stromal/stem cells (MSCs) in meniscus allograft tissue. We investigated the injectable cell quantity, survival rate, migration, and proliferation ability of MSCs up to 28 days of incubation. In this controlled laboratory study, seven fresh‐frozen human allografts were injected with human allogeneic MSCs. Cells were labeled and histological characteristics were microscopically imaged up to 28 days. Mock‐injected menisci were included as negative controls in each experiment. Toluidine blue staining demonstrated that a 100‐µl volume can be injected while retracting and rotating the inserted needle. Immediately after injection, labeled MSCs were distributed throughout the injection channel and eventually migrated into the surrounding tissues. Histological assessment revealed that MSCs cluster in disc‐like shapes, parallel to the intrinsic lamination of the meniscus and around the vascular network. Quantification showed that more than 60% of cells were present in horizontally injected grafts and more than 30% were observed in vertically injected samples. On Day 14, cells adopted a spindle‐shaped morphology and exhibited proliferative and migratory behaviors. On Day 28, live/dead ratio assessment revealed an approximately 80% cell survival. The study demonstrated the feasibility of injecting doses of MSCs (>0.1 million) in meniscus allograft tissue with active cell proliferation, migration, and robust cell survival.