Tibiofemoral Contact Mechanics After Horizontal or Ripstop Suture in Inside-Out and Transtibial Repair for Meniscus Radial Tears in a Porcine Model

Animal models used in meniscal repair research from ex vivo to in vivo: A systematic review

This systematic review, registered with Prospero, aims to identify an optimal animal model for meniscus repair research, moving from ex vivo experimentation to in vivo studies. Data sources included PubMed, Medline, all Evidence-Based Medicine Reviews, Web of Science, and Embase searched in March 2023. Studies were screened using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Extracted data including animal model, type of experiment, type of tear, surgical techniques, and measured outcomes, were recorded, reviewed, and analyzed by four independent reviewers. The SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) Rob tool was used for critical appraisal and risk of bias assessment. Out of 11,719 studies, 72 manuscripts were included for data extraction and analysis; 41 ex vivo extra-articular studies, 20 ex vivo intra-articular studies, and only 11 in vivo studies. Six animal models were employed: porcine, bovine, lapine, caprine, canine, and ovine. Longitudinal lesions were the most frequently studied tear pattern and sutures the most common repair technique. Studied outcomes focused mainly on biomechanical assessments and gross observations. This systematic review can guide researchers in their choice of animal model for meniscus repair research; it highlighted the strengths of the porcine, caprine, and bovine models for ex vivo cadaveric studies, while the porcine and caprine models were found to be more suited to in vivo studies due to their similarities with human anatomy. Research teams should familiarize themselves with the advantages and disadvantages of various animal models before initiating protocols to improve standardization in the field.

Selective Extracellular Matrix Guided Mesenchymal Stem Cell Self-Aggregate Engineering for Replication of Meniscal Zonal Tissue Gradient in a Porcine Meniscectomy Model

Degenerative meniscus tears (DMTs) are prevalent findings in osteoarthritic knees, yet current treatment is mostly limited to arthroscopic partial meniscectomy rather than regeneration, which further exacerbates arthritic changes. Translational research regarding meniscus regeneration is hindered by the complex, composite nature of the meniscus which exhibit a gradient from inner cartilage-like tissue to outer fibrous tissue, as well as engineering hurdles often requiring growth factors and cross-linking agents. Here, a meniscus zonal tissue gradient is proposed using zone-specific decellularized meniscus extracellular matrix (DMECM) and autologous synovial mesenchymal stem cells (SMSC) via self-aggregation without the use of growth factors or cross-linking agents. Combination with zone-specific DMECM during self-aggregation of MSCs forms zone-specific meniscus tissue that reflects the respective DMECM harvest site. The implantation of these constructs leads to the regeneration of meniscus tissue resembling the native meniscus, demonstrating inner cartilaginous and outer fibrous characteristics as well as recovery of native meniscal microarchitecture in a porcine partial meniscectomy model at 6 months. In all, the findings offer a potential regenerative therapy for DMTs that may improve current partial meniscectomy-based patient care.

Several Techniques Exist With Favorable Biomechanical Outcomes in Radial Meniscus Tear Repair-A Systematic Review

PURPOSE

To compare biomechanical properties of various radial tear repair techniques in the medial and lateral menisci.

METHODS

A search was performed for key words regarding mechanical properties of repair of radial meniscal tears in PubMed, Embase, CINAHL, Scopus, and Cochrane databases, yielding 1791 articles. Articles were screened using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines against inclusion criteria and underwent Methodological Index for Non-Randomized Studies (MINORS) methodologic quality assessment. Repair constructs evaluated were classified based on repair technique, use of a transtibial augmentation, and the number, orientation, and pattern of stitches. Results published across different studies were compared but not subjected to meta-analysis due to variability in testing procedures and heterogeneity of repair methods.

RESULTS

We identified 20 studies that performed mechanical testing on 21 different radial meniscal tear repair techniques. The greatest reported mean load-to-failure (LtF) were the transtibial 2-tunnel + 4 horizontal inside-out sutures (191.2 N ± 17.3, cadaver) and all-inside double vertical repair (146.3 N ± 36.2, porcine). The transtibial technique improved LtF and displacement of an inside-out (IO) horizontal repair. All-inside vertical repairs demonstrated greater LtF, stiffness, and displacement compared with IO horizontal repairs in 2 studies. Compared with IO double horizontal repairs, all-inside double vertical or IO double horizontal repairs with reinforcing stitches parallel to the tear exhibited greater LtF in 3 studies and stiffness in 2 studies. Two studies reported that parallel reinforcing stitches significantly reduced suture tear-through compared with similar, nonreinforced repairs. Mean MINORS score for all studies analyzed was 19.88 ± 1.47 points.

CONCLUSIONS

A systematic review demonstrated that there may be alternatives to traditional IO horizontal repairs for radial meniscus tears. Less-invasive all-inside vertical techniques reinforced with suture parallel to the tear instead of standard IO horizontal sutures may improve strength of repair. In addition, transtibial 2-tunnel augmentation may also increase strength of radial meniscus tear repairs.

CLINICAL RELEVANCE

There may be alternatives to IO horizontal repairs for radial meniscus tears.

Two Uncommon Complications Related to Suture Knots After Meniscal All-Inside Suture Repair: A Case Report

CASE

A 17-year-old male patient suffered a radial lateral meniscus tear and underwent an arthroscopic all-inside suture repair. After 7 months, the patient experienced catching. Magnetic resonance imaging and computed tomography revealed an intra-articular loose body without calcification, which was removed surgically. The excised specimen was histopathologically confirmed to be a necrotic meniscus fragment with a suture knot. In addition, cartilage damage because of suspected impingement by a residual suture knot was observed. After removing the loose body and knot, the patient's symptoms were relieved, and he returned to sports.

CONCLUSION

Suture knot-related complications should be considered while performing meniscal repairs.

Repair Technique for Displaced Meniscal Flap Tears Indicated by MRI Comma Sign

The meniscus comma sign has been described for displaced flap tears of the meniscus. These meniscus tears are displaced into the tibia or femoral recesses and can be often difficult to diagnose intraoperatively. We describe the technique of diagnosis and treatment of a large displaced lateral meniscus flap tear, presenting as a meniscus comma sign. The identification of the meniscus comma sign on consecutive magnetic resonance imaging (MRI) cuts suggest a flap tear of a significant size that indicates reparability. The technique would be to lift the meniscus flap from the meniscotibial recess, reduce it and then repair it with an all-inside meniscus repair or by hybrid meniscus repair techniques.

Editorial Commentary: Efforts to Heal Meniscal Radial Tears Are Ongoing

Meniscal radial tears are equivalent to the meniscectomized state. However, successful healing rates by current repair methods for meniscal radial tears are still not satisfactory. Several suture configurations that could approximate the tear gap and stabilize meniscal tissue have been developed to overcome the shortcomings of simple horizontal stitches and cross stitches. The hybrid stitch method, composed of horizontal stitches and vertical stitches, has been introduced. This method can provide stable fixation because the vertical stitches suture the bundle of circumferential fibers, and the vertical stitches act as rip stops for the horizontal stitches. However, it is still challenging to heal meniscal radial tears in avascular areas or complex tears. In treating radial tears, it is important not only to improve suture mechanics but also to promote biologic healing potential.