Biological enhancement of meniscus repair and replacement

Regeneration of meniscal avascular zone using autogenous meniscal fragments in a rabbit model

Background

To investigate the effects of autologous meniscus fragment (AMF) implantation on injury in the meniscal avascular zone in mature rabbits.

Methods

Adult New Zealand white rabbits were randomly divided into two groups. Massive one-piece meniscus tissue was implanted in situ as control. In the experimental group, AMF was used to repair the meniscal injury in the avascular zone. Meniscal damage was assessed by gross observation of the degree of healing and histological semi-quantitative evaluation within 12 weeks postoperatively. The healing of meniscus interface was assessed by gross observation semiquantitative scoring and microscopic examination hematoxylin and eosin (H&E) staining at 2, 4, 8, and 12 weeks after surgery. The expressions of proliferating cell nuclear antigen (PCNA), collagen type I (COL1A1), and collagen type II (COL2) were detected by immunohistochemical staining.

Results

The degree of healing in the AMF group showed a significant increase over time (P < 0.05); the AMF group showed higher gross scores than the control group at 4, 8, and 12 weeks after surgery (P < 0.05). The histological scores in the AMF group were significantly higher than those in the control group at 4, 8, and 12 weeks after surgery (P < 0.05). The protein expression of PCNA in the AMF group was greater than that in the control group at 2, 4, and 8 weeks after surgery (P < 0.05). In addition, compared with the control group, the protein levels of COL1A1 and COL2 were significantly upregulated at each time-point. At 2 and 4 weeks after surgery, the expression level of COL1A1 increased in both groups followed by a gradual decrease after 8 weeks (P < 0.05). At 2, 4, 8, and 12 weeks after surgery, the expression levels of COL2 showed a gradual decrease in both groups (P < 0.05).

Conclusions

Our study demonstrated that the AMF method can promote the repair of rabbit meniscal injury in the avascular zone, and this method may potentially be used for clinical application.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-022-01663-3.

Development of a Micronized Meniscus Extracellular Matrix Scaffold for Potential Augmentation of Meniscal Repair and Regeneration

Decellularized scaffolds composed of extracellular matrix (ECM) hold promise for repair and regeneration of the meniscus, given the potential for ECM-based biomaterials to aid in stem cell recruitment, infiltration, and differentiation. The objectives of this study were to decellularize canine menisci to fabricate a micronized, ECM-derived scaffold and to determine the cytocompatibility and repair potential of the scaffold ex vivo. Menisci were decellularized with a combination of physical agitation and chemical treatments. For scaffold fabrication, decellularized menisci were cryoground into a powder and the size and morphology of the ECM particles were evaluated using scanning electron microscopy. Histologic and biochemical analyses of the scaffold confirmed effective decellularization with loss of proteoglycan from the tissue but no significant reduction in collagen content. When washed effectively, the decellularized scaffold was cytocompatible to meniscal fibrochondrocytes, synoviocytes, and whole meniscal tissue based on the resazurin reduction assay and histologic evaluation. In an ex vivo model for meniscal repair, radial tears were augmented with the scaffold delivered with platelet-rich plasma as a carrier, and compared to nonaugmented (standard-of-care) suture techniques. Histologically, there was no evidence of cellular migration or proliferation noted in any of the untreated or standard-of-care treatment groups after 40 days of culture. Conversely, cellular infiltration and proliferation were noted in scaffold-augmented repairs. These data suggest the potential for the scaffold to promote cellular survival, migration, and proliferation ex vivo. Further investigations are necessary to examine the potential for the scaffold to induce cellular differentiation and functional meniscal fibrochondrogenesis.

Meniscal Preservation is Important for the Knee Joint

Native joint preservation has gained importance in recent years. This is mostly to find solutions for limitations of arthroplasty. In the knee joint, the menisci perform critical functions, adding stability during range of motion and efficiently transferring load across the tibiofemoral articulation while protecting the cartilage. The menisci are the most common injury seen by orthopedicians, especially in the younger active patients. Advances in technology and our knowledge on functioning of the knee joint have made meniscus repair an important mode of treatment. This review summarizes the various techniques of meniscus tear repair and also describes biological enhancements of healing.

Effect of Microfracture on Meniscal Tear Healing in a Goat (Capra hircus) Model

Meniscal injuries are an extremely common cause of knee pain. Meniscal repairs performed with concomitant anterior cruciate ligament reconstruction appear to heal at a higher rate than meniscal repairs performed in isolation. This may be due in part to the release of marrow elements into the knee and the time of meniscal repair. In cases of isolated meniscal repair, some orthopedic surgeons use microfracture to release marrow elements into the joint as an adjunct to enhance meniscal healing. This study evaluated rates of meniscal tear healing with or without the performance of microfracture in a goat (Capra hircus) model. Forty castrated young adult male goats underwent either a horizontal or a longitudinal 1.0-cm meniscal tear with or without microfracture. All procedures were performed open, in a bloodless field. Meniscal tears were created in the peripheral half of the body of the medial meniscus. The goats were euthanized at 6 months, and meniscal tears were analyzed and classified as complete healing, partial healing, or no healing by direct visualization. A probe was used as an aid to evaluate and classify the meniscal tears. Twenty (87%) of 23 goat meniscal tears showed at least partial healing when performed with concomitant microfracture. Only 5 (29%) of 17 menisci showed any healing in goats that did not receive microfracture. This difference in healing rates was statistically significant (P<.001). Fifteen (65%) meniscal tears accomplished with microfracture were completely healed, whereas only 2 (12%) menisci showed complete healing without microfracture (P<.001). The results of this study suggest that the release of bone marrow elements into the knee by microfracture improves meniscal healing rates.

Repair of isolated horizontal meniscal tears with all-inside suture materials using the overlock method: outcome study with a minimum 2-year follow-up

Background

This study aimed to consider the use of a meniscal repair in patients in order to close the horizontal cleavage extending up to the avascular zone. The hypothesis was to examine the clinical and arthroscopic outcomes following meniscal repair of degenerative horizontal cleavage tears with new-generation all-inside suture materials using the overlock method.

Methods

We retrospectively reviewed a consecutive series of 55 patients which had a horizontal pattern, and finally, 27 patients with a horizontal tear only which required no additional intra-articular surgical intervention were included in the study. Arthroscopic meniscal repair was performed using the overlock method. Functional outcomes were evaluated using Lysholm knee scoring scale, Cincinnati scores, subjective International Knee Documentation Committee (IKDC) criteria and Tegner activity scale. Assessment of meniscal healing was evaluated clinically by the presence of meniscal signs. The preoperative and postoperative MRIs were examined.

Results

The mean follow-up period was 29 months (range, 24–38). The mean Lysholm score improved significantly from 59.5 ± 12.4 points preoperatively to 90.0 ± 4.7 points postoperatively (P < 0.0001). The Cincinnati score increased from 14.8 ± 5.3 to 26.9 ± 1.6 (P < 0.0001). The Tegner activity score increased from 3.7 ± 1.4 to 6.4 ± 1.6 (P < 0.0001). The mean IKDC subjective score also improved significantly from 48.5 ± 9.8 preoperatively to 90.4 ± 5.0 postoperatively (P < 0.0001).

Conclusion

Meniscal repair of degenerative horizontal tears using the overlock method resulted in improved Lysholm and IKDC subjective scores. With careful selection of the patients and the horizontal meniscus tears, the success of the meniscus repairs increases. Repair can be recommended for all horizontal meniscus tears which can be repaired arthroscopically.

Arthroscopic repair of horizontal meniscal cleavage tears with marrow-stimulating technique

PURPOSE

The purpose of this study was to evaluate patients after arthroscopic repair of meniscal horizontal tears with a marrow-stimulating technique through clinical signs and second-look arthroscopy.

METHODS

We retrospectively reviewed a consecutive series of 32 meniscal repairs with horizontal cleavage tears and evaluated them through clinical assessment and second-look arthroscopic examinations. Arthroscopic meniscal repair and a marrow-stimulating technique were performed. Functional outcomes were evaluated using the visual analog scale (VAS) pain score, Lysholm knee scoring scale, and Tegner activity scale. Assessment of meniscal healing was evaluated clinically by the presence of meniscal signs; second-look arthroscopy was performed in 11 patients. Correlation between chronicity of a meniscal lesion (time from initial symptom [TFIS]) and meniscal healing was evaluated.

RESULTS

The mean follow-up period was 45.6 ± 13.9 months. Improvements in mean VAS scores from 6.7 to 1.9 (P < .001) were observed. The Lysholm score increased from 48.0 ± 14.4 to 92.0 ± 6.3 (P < .001). The Tegner activity score increased from 3.3 ± 1.1 to 6.8 ± 0.8 (P < .001). At the last follow-up, 29 of 32 patients (91%) were evaluated as healing in the clinical assessment. Of the 11 patients who underwent second-look arthroscopy, 8 (73%) showed complete healing, 2 (18%) had incomplete healing, and 1 (9%) failed to heal. Correlation between TFIS and meniscal healing was clinically significant (P = .001) but arthroscopically insignificant (P = .085) on second-look arthroscopy.

CONCLUSIONS

The meniscal repair procedure for horizontal cleavage tears in the present study suggests an alternative treatment option to approach the treatment of meniscal tears extending into the avascular zone and degenerative tissue. The marrow-stimulating technique using a cannulated reamer can be considered as an alternative method for the augmentation of meniscal healing.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

The Role of Cells in Meniscal Guided Tissue Regeneration: A Proof of Concept Study in a Goat Model

OBJECTIVE

Successful repair of defects in the avascular zone of meniscus remains a challenge in orthopedics. This proof of concept study aimed to investigate a guided tissue regeneration approach for treatment of tears in meniscus avascular zone in a goat model.

DESIGN

Full-depth longitudinal tear was created in the avascular zone of the meniscus and sutured. In the two treatment groups, porcine collagen membrane was wrapped around the tear without (CM) or with injection of expanded autologous chondrocytes (CM+cells), whereas in the control group the tear remained only sutured. Gait recovery was evaluated during the entire follow-up period. On explantation at 3 and 6 months, macroscopic gross inspection assessed healing of tears, degradation of collagen membrane, potential signs of inflammation, and osteoarthritic changes. Microscopic histology scoring criteria were developed to evaluate healing of tears, the cellular response, and the inflammatory response.

RESULTS

Gait recovery suggested protective effect of collagen membrane and was supported by macroscopical evaluation where improved tear healing was noted in both treated groups. Histology scoring in CM compared to suture group revealed an increase in tear margins contact, newly formed connective tissue between margins, and cell formations surrounded with new matrix after 3 months yet not maintained after 6 months. In contrast, in the CM+cells group these features were observed after 3 and 6 months.

CONCLUSIONS

A transient, short-term guided tissue regeneration of avascular meniscal tears occurred upon application of collagen membrane, whereas addition of expanded autologous chondrocytes supported more sustainable longer term tear healing.

Why menisci show higher healing rate when repaired during ACL reconstruction? Growth factors release can be the explanation

PURPOSE

Healing rate of meniscus repair is higher when the suture is associated with anterior cruciate ligament reconstruction. A possible explanation can be a different pattern of release of growth factors between anterior cruciate ligament reconstruction and isolated meniscus surgery. Hypothesis of this study is that the concentrations of bFGF, TGF-β and platelet-derived growth factor (PDGF) in joint fluid, immediately after single-bundle anterior cruciate ligament reconstruction and arthroscopic partial meniscectomy, can be different.

METHODS

Twenty consecutive patients underwent partial medial meniscectomy and twenty consecutive patients underwent single-bundle anterior cruciate ligament reconstruction with hamstring grafts were enrolled in the study. Thirty minutes after the end of the surgical procedure, a sample of joint fluid, as well of venous blood, was collected from all the patients. Concentrations of growth factors were determined by enzyme-linked immunosorbent assay.

RESULTS

The peripheral blood concentration of TGF-β, bFGF and PDGF was comparable between partial meniscectomy and anterior cruciate ligament reconstruction groups. No differences between the two surgical techniques were also found in term of TGF-β and bFGF joint fluid concentration, whereas joint PDGF concentration of anterior cruciate ligament reconstruction patients was significantly higher than the one found in partial meniscectomy patients.

CONCLUSIONS

A significant growth factors release was detected in the knee joint during arthroscopic surgery. PDGF concentration was significantly higher in anterior cruciate ligament reconstructed knee than in the meniscectomy group. PDGF can play an important role enhancing the healing response of meniscus suture and can be one of the biological reasons of the higher meniscal healing rate in anterior cruciate ligament reconstructed knee.

Bonding and fusion of meniscus fibrocartilage using a novel chondroitin sulfate bone marrow tissue adhesive

The weak intrinsic meniscus healing response and technical challenges associated with meniscus repair contribute to a high rate of repair failures and meniscectomies. Given this limited healing response, the development of biologically active adjuncts to meniscal repair may hold the key to improving meniscal repair success rates. This study demonstrates the development of a bone marrow (BM) adhesive that binds, stabilizes, and stimulates fusion at the interface of meniscus tissues. Hydrogels containing several chondroitin sulfate (CS) adhesive levels (30, 50, and 70 mg/mL) and BM levels (30%, 50%, and 70%) were formed to investigate the effects of these components on hydrogel mechanics, bovine meniscal fibrochondrocyte viability, proliferation, matrix production, and migration ability in vitro. The BM content positively and significantly affected fibrochondrocyte viability, proliferation, and migration, while the CS content positively and significantly affected adhesive strength (ranged from 60±17 kPa to 335±88 kPa) and matrix production. Selected material formulations were translated to a subcutaneous model of meniscal fusion using adhered bovine meniscus explants implanted in athymic rats and evaluated over a 3-month time course. Fusion of adhered meniscus occurred in only the material containing the highest BM content. The technology can serve to mechanically stabilize the tissue repair interface and stimulate tissue regeneration across the injury site.