Biomaterials and Meniscal Lesions: Current Concepts and Future Perspective

Menisci are crucial structures for knee homeostasis. After a meniscal lesion, the golden rule, now, is to save as much meniscus as possible; only the meniscus tissue that is identified as unrepairable should be excised, and meniscal sutures find more and more indications. Several different methods have been proposed to improve meniscal healing. They include very basic techniques, such as needling, abrasion, trephination and gluing, or more complex methods, such as synovial flaps, meniscal wrapping or the application of fibrin clots. Basic research of meniscal substitutes has also become very active in the last decades. The aim of this literature review is to analyze possible therapeutic and surgical options that go beyond traditional meniscal surgery: from scaffolds, which are made of different kind of polymers, such as natural, synthetic or hydrogel components, to new technologies, such as 3-D printing construct or hybrid biomaterials made of scaffolds and specific cells. These recent advances show that there is great interest in the development of new materials for meniscal reconstruction and that, with the development of new biomaterials, there will be the possibility of better management of meniscal injuries

Second-Look Arthroscopic Evaluation of Healing Rates After Arthroscopic Repair of Meniscal Tears: A Systematic Review and Meta-analysis

Background: Evaluation of meniscal healing status after repair is important, as it allows the surgeon to inform patients whether they can increase their activities or return to sports. Purpose: To identify the healing rates after arthroscopic repair of meniscal tears via second-look arthroscopic evaluation. Study Design: Systematic review; Level of evidence, 4. Methods: Searches of PubMed, Embase, Scopus, and the Cochrane databases were conducted to identify relevant studies published before June 1, 2020. Studies were eligible for this meta-analysis if they provided data regarding healing status of the meniscus at second-look arthroscopy. Random-effects meta-analyses were generated to provide pooled meniscal healing estimates. We further performed subgroup analysis to investigate the healing rates of the meniscus under different situations. Results: A total of 41 studies with 1908 individuals were included in the study. The pooled analysis showed the complete healing rate was 74% (95% confidence interval [CI], 67%-80%), the partial healing rate was 10% (95% CI, 6%-16%), and the failure rate was 12% (95% CI, 10%-15%) for arthroscopic repair of meniscal tears via second-look arthroscopic evaluation. Sensitivity analysis demonstrated that no individual study affected the overall healing rate by >1%. Subgroup analysis found higher meniscal healing rates in patients with the following characteristics: age <40 years, male, body mass index <26, red-red tear location, tear in posterior horn, vertical tear, outside-in technique, repair concomitant with anterior cruciate ligament reconstruction, weight-restricted rehabilitation, and time interval from meniscal repair to second-look arthroscopy >12 months. Conclusion: In this systematic review, the complete healing rate was 74%, the partial healing rate was 10%, and the failure rate was 12% for arthroscopic repair of meniscal tears via second-look arthroscopic evaluation.

Association Between Transtibial Meniscus Root Repair and Rate of Meniscal Healing and Extrusion on Postoperative Magnetic Resonance Imaging: A Prospective Multicenter Study

Background: Prospective studies evaluating second-look imaging of meniscus root repair using a transtibial pull-out technique are limited; therefore, optimal surgical indications and the technique for meniscus root repair remain uncertain. Hypothesis: It was hypothesized that there would be a high rate of healing, improvement in meniscal extrusion, and prevention of articular cartilage degeneration and subchondral bone abnormalities after meniscus root repair. Study Design: Case series; Level of evidence, 4. Methods: Consecutive patients undergoing transtibial root repair were prospectively enrolled at 2 orthopaedic centers between March 2017 and January 2019. Pre- and postoperative magnetic resonance imaging (MRI) scans were reviewed by a musculoskeletal radiologist in a blinded fashion for meniscal healing, quantification of extrusion, articular cartilage grade, subchondral bone changes, and coronary/meniscotibial ligament abnormalities. Given persistent extrusion observed on postoperative MRI scans, an additional 10 patients gave consent and were enrolled for immediate (before weightbearing) postoperative MRI scans. Results: A total of 45 patients (16 male, 29 female; mean ± standard deviation age, 42.3 ± 12.9 years; body mass index, 31.6) were prospectively enrolled in the study; there were 47 meniscus root repairs: 29 medial and 18 lateral (2 with both). Postoperative MRI was obtained at an average of 6.3 months (range, 5.1-8 months); 98% of meniscal repairs had evidence of healing. Mean extrusion increased significantly, from 1.9 ± 1.5 mm preoperatively to 2.6 ± 1.4 mm postoperatively ( P = .03). There was no significant progression of chondromalacia grade, subchondral edema, insufficiency fracture, subchondral cysts, or subchondral collapse. In the additional 10-patient cohort, the mean preoperative extrusion (1.6 ± 1.2 mm) was not significantly different from that immediately postoperatively (2.0 ± 1.0 mm; P = .23). Conclusion: Prospective MRI analysis of transtibial meniscus root repair confirmed a high rate of meniscal healing and no observable progression of cartilage degeneration or subchondral bone abnormalities at the short-term follow-up. However, meniscal extrusion worsened in the first 6 months after surgery. Registration: NCT03037242 ( ClinicalTrials.gov identifier).

Effect of concurrent repair of medial meniscal posterior root tears during high tibial osteotomy for medial osteoarthritis during short-term follow-up: a systematic review and meta-analysis

Background Medial meniscal posterior root tears (MMPRTs) are frequently associated with medial compartment osteoarthritis, leading to loss of meniscal hoop tension. This study aimed to evaluate the efficacy of concurrent MMPRT repair during high tibial osteotomy (HTO) compared to HTO alone in patients with medial osteoarthritis and MMPRTs. Methods The MEDLINE/PubMed, EMBASE, and Cochrane Library databases were searched for studies reporting on concurrent MMPRT repair during HTO. Pre- and postoperative data were pooled to investigate the treatment effects of concurrent MMPRT repair during HTO, and compare postoperative clinical, radiological, and arthroscopic outcomes including cartilage status and healing event rates according to the arthroscopic classification of MMPRT healing (complete, partial [lax or scar tissue], or failed healing) between HTO patients with and without concurrent MMPRT repair. The random-effect model was used to pool the standardized mean differences, odds ratios (ORs), 95% confidence intervals (CIs), and event rates. Results Seven patient subgroups in six articles divided according to meniscal repair techniques were included in the final analysis. Concurrent MMPRT repair during HTO significantly improved the Lysholm score, while no intergroup differences were observed in the postoperative Lysholm and WOMAC scores, as well as radiological and arthroscopic outcomes. Those who underwent concurrent MMPRT repair showed a higher rate of complete meniscal healing (OR: 4.792, 95% CI, 1.95–11.79), with a pooled rate of complete meniscal healing of 0.327 (95% CI, 0.19–0.46). Conclusion Concurrent MMPRT repair during HTO for medial osteoarthritis with MMPRTs has little benefits on the clinical, radiological, and arthroscopic outcomes during short-term follow-up. Further accumulation of evidence is needed for long-term effects.

Clinical Outcomes of Meniscus Repair with or without Multiple Intra-Articular Injections of Platelet Rich Plasma after Surgery

Preservation of the meniscal volume is crucial in meniscus repair. The goal of this study was to evaluate the clinical outcome of repeated intra-articular platelet-rich plasma (PRP) injections after arthroscopic repair of a traumatic meniscal tear. We retrospectively reviewed 61 primary meniscal repairs in 61 patients (PRP group: 30; non-PRP: 31) from 2017 to 2018. Patients in the PRP group received repeated intra-articular PRP injections in week 2,4,6 after the primary meniscus repair. Subsequent meniscal repair treatment or meniscectomy, knee arthroplasty, and IKDC changes of less than 11.5 points were defined as healing failures. After following up for at least 24 months, the IKDC score was 75.1 ± 13.6, and the Lysholm score was 80.6 ± 14.9 in the PRP group and 72.6 ± 15.8 (IKDC) and 77.7 ± 17.2 (Lysholm) in the non-PRP group. Healing rates of the PRP and the non-PRP groups were 93.3% (Kaplan-Meier 91.6%) and 87.1% (Kaplan-Meier 84.7%), respectively (log rank test p = 0.874). Our study is the first to use multiple intra-articular PRP injections to facilitate meniscal healing after meniscal repair. Though selection bias may be present in this study, the PRP group had similar functional outcome and healing rate compared to non-PRP group.

Isolated meniscus injuries in skeletally immature children and adolescents: state of the art

The prevalence of isolated meniscal injuries in children and adolescents is low; however, we see an increase mainly due to intensified sports-related activities at an early age. A meniscal repair should be attempted whenever possible as children present with increased meniscal healing potential. The diagnosis and management of meniscal tears involve both patient factors and tear characteristics: size, anatomical location and associated injuries. Special attention should be given to the feature of discoid menisci and related tears as they require a specific management plan. This state-of-the-art review highlights the most recent studies on clinical evaluation, surgical techniques, tips and tricks, pitfalls, outcomes, return-to-sports, geographical differences and future perspectives related to meniscal injuries in children and adolescents.

Development of a novel meniscal sheet scaffold and its effectiveness for meniscal regeneration in a rabbit defect model

This study evaluated the biomechanical strength of a novel two-layer meniscal sheet scaffold (MSS) consisting of polyglycolic acid and poly-Llactic acid/caprolactone and investigated meniscal healing using wrapping treatment for meniscal defect model in a rabbit. The ultimate failure load of the MSS was determined using a tensile testing machine, in vitro. A 2-mm cylindrical defects were created at the medial meniscus of rabbit knees (n = 40). Each knee was assigned to one of two groups. The defect group was not treated and the MSS group underwent wrapping treatment with MSS. Menisci were harvested at 2, 4, 8, and 12 weeks post-implantation. The regenerated meniscus and defect size were evaluated using macrophotographs. Ishida scores for regenerated tissue were determined using Safranin-O/Fast Green staining. Immunohistochemical analysis of Ki-67 for cell proliferation, anti-type I and II collagen antibodies for structure of the regenerated tissue was elucidated. Medial femoral cartilage was stained with Safranin-O/Fast Green and evaluated with Osteoarthritis Research Society International (OARSI) scores. The strength of MSS was maintained over 90% from initial time point to 4 weeks after hydrolysis and over 60% of the strength remained at 8 weeks. The surface area of the meniscus was larger and the defect size smaller in the MSS group than in the defect group at 8 and 12 weeks. Ishida scores revealed that the MSS group improved significantly compared to that of the defect group at all postsurgery time points evaluated. Ki-67 positive cell ratio was significantly higher in the MSS group. OARSI score of the defect group was significantly higher and the defect group showed progressive degeneration in the articular cartilage from 8 to 12 weeks. Overall, wrapping meniscus defects with MSS was useful for accelerating meniscal healing from an early stage and beneficial for tissue regeneration and promoting extracellular matrix maturation.