The potential of using semitendinosus tendon as autograft in rabbit meniscus reconstruction

Development of a novel approach for restoration of the meniscus using silk-elastin in a rabbit meniscus injury model

BACKGROUND

Limited healing potential of the meniscus remains a burden for the successful repair of meniscus injuries in the orthopaedic fields. Silk-elastin (SE) is a novel recombinant protein with favorable properties for wound healing. This proof-of-concept study aimed to investigate the therapeutic effect of silk-elastin in a rabbit meniscal defect model.

METHODS

A migration assay using rabbit meniscus and synovial cells with various concentrations of SE in a culture medium was conducted to investigate the mechanism of meniscal healing by SE. Additionally, cylindrical defects with a 1.5 mm diameter were created at the anterior horn of the medial meniscus of rabbits. The animals were divided into three groups: 1) the Blank group; defect only, 2) the Col I group; implantation of type I atelocollagen sponge, and 3) the SE group; implantation of SE (150 mg/ml) sponge. Whole medial menisci were harvested at 4, 8, 12, and 24 weeks after surgery. Histological analyses including immunohistochemical staining were performed to assess meniscal healing.

RESULTS

In vitro study, Migration assay demonstrated a significantly higher number of migrated cells only in synovial cells. Especially, the SE concentration of 10 µg/mL demonstrated the highest number of migrated cells compared with other concentrations. In vivo study, the SE group exhibited significantly higher Ishida scores than other groups at all time points. Furthermore, the SE group showed higher synovial coverage scores than the Col I group at 4 and 8 weeks. Immunohistochemical staining demonstrated higher type II collagen staining in the SE group compared to other groups at 12 weeks. Implanted SE was efficiently replaced by safranin-O staining positive tissue within 8 weeks.

CONCLUSIONS

SE could effectively repair a meniscal defect by inducing coverage of synovial cells. SE has the potential to be a useful material for meniscal repair.

Reconstruction of medial meniscus posterior portion deficiency in pigs with an autologous patellar tendon graft: an experimental study

OBJECTIVE

This study was performed to investigate the effectiveness of two surgical procedures, autologous patellar tendon graft reconstruction and trans-tibial plateau pull-out repair, using a pig model. The primary focus was to assess the repair capability of medial meniscus posterior portion (MMPP) deficiency, the overall structural integrity of the meniscus, and protection of the femoral and tibial cartilage between the two surgical groups. The overall aim was to provide experimental guidelines for clinical research using these findings.

METHODS

Twelve pigs were selected to establish a model of injury to the MMPP 10 mm from the insertion point of the tibial plateau. They were randomly divided into three groups of four animals each: reconstruction (autologous tendon graft reconstruction of the MMPP), pull-out repair (suture repair of the MMPP via a trans-tibial plateau bone tunnel), and control (use of a normal medial meniscus as the negative control). The animals were euthanized 12 weeks postoperatively for evaluation of the meniscus, assessment of tendon bone healing, and gross observation of knee joint cartilage. The tibial and femoral cartilage injuries were evaluated using the International Society for Cartilage Repair (ICRS) grade and Mankin score. Histological and immunohistochemical staining was conducted on the meniscus-tendon junction area, primary meniscus, and tendons. The Ishida score was used to evaluate the regenerated meniscus in the reconstruction group. Magnetic resonance imaging (MRI) was used to evaluate meniscal healing.

RESULTS

All 12 pigs recovered well after surgery; all incisions healed without infection, and no obvious complications occurred. Gross observation revealed superior results in the reconstruction and pull-out repair groups compared with the control group. In the tibial cartilage, the reconstruction group had ICRS grade I injury whereas the pull-out repair and control groups had ICRS grade II and III injury, respectively. The Mankin score was significantly different between the reconstruction and control groups; histological staining showed that the structure of the regenerated meniscus in the reconstruction group was similar to that of the original meniscus. Immunohistochemical staining showed that the degree of type I and II collagen staining was similar between the regenerated meniscus and the original meniscus in the reconstruction group. The Ishida score was not significantly different between the regenerated meniscus and the normal primary meniscus in the reconstruction group. MRI showed that the MMPP in the reconstruction and pull-out repair groups had fully healed, whereas that in the control group had not healed.

CONCLUSION

Autologous patellar tendon graft reconstruction of the MMPP can generate a fibrocartilage-like regenerative meniscus. Both reconstruction and pull-out repair can preserve the structural integrity of the meniscus, promote healing of the MMPP, delay meniscal degeneration, and protect the knee cartilage.

Risk factors of incomplete healing following medial meniscus posterior root tear repair with gracilis tendon

To evaluate the clinical efficacy and meniscus healing rates of the arthroscopically assisted tendon graft fixation of the medial meniscus posterior root tears (MMPRTs), and to identify some independent risk factors correlated with meniscal root healing status. We conducted a retrospective study with 129 patients who received arthroscopically assisted tendon graft fixation of the MMPRTs between January 2018 and September 2021. Functional recovery of the knee was evaluated and meniscal root healing status was assessed. The associations between different clinical factors and meniscal root healing status were analyzed. 98 (76.0%) patients had complete meniscal root healing with a minimum 2-year follow-up, and the Lysholm score, international knee documentation committee score, and visual analogue scale score were significantly improved at final follow-up (P < 0.001; respectively). Binary logistic regression models analysis and the receiver operating characteristic curve was performed to detect independent risk factors for incomplete healing, and these results indicated that age (OR = 1.095, P = 0.039), body mass index (BMI) (OR = 1.259, P = 0.018), preoperative meniscus extrusion (OR = 5.181, P < 0.001) and varus degree (OR = 7.764, P < 0.001) were the independent risk factors correlated with incomplete healing in patients with repaired MMPRTs. In conclusion, the arthroscopically assisted tendon graft fixation of the MMPRTs can provide good clinical and radiological outcome. Additionally, we identified age > 37.5 years, BMI > 24.5 kg/m2, preoperative meniscus extrusion > 2.7 mm and varus degree > 3.3° as independent risk factors correlated with incomplete meniscus root healing status.

Younger patients, lower BMI, complete meniscus root healing, lower HKA degree and shorter preoperative symptom duration were the independent risk factors correlated with the good correction of MME in patients with repaired MMPRTs

PURPOSE

To evaluate the clinical and radiological outcomes of arthroscopically assisted tendon graft anatomic reinforced reconstruction of the medial meniscus posterior root tears (MMPRTs) and identify relevant factors affecting the correction of medial meniscal extrusion (MME).

METHODS

Fifty-three MMPRTs patients who underwent arthroscopically assisted tendon graft reconstruction of the meniscal root between 2018 and 2020 were evaluated retrospectively. the patients were divided into 2 groups according to the correction of MME (maintained MME group: 32 cases vs. increased MME group: 21 cases). The clinical and radiological outcomes of arthroscopically assisted tendon graft reconstruction of the meniscal root, including postoperative correction of MME and functional recovery of the knee were assessed in this study, and potential independent risk factors that could influence the correction of MME were also evaluated.

RESULTS

The functional recovery of the knee was significantly improved at the end of follow-up (P < 0.001; respectively), furthermore, a comparison of the final functional outcomes between the groups showed that the mean Lysholm score and IKDC score of the maintained MME group were significantly improved than those of increased MME group. 60.4% had good correction of MME, and patients with complete healing had better extrusion correction than those with partial healing and non-healing. Binary logistic regression models analysis indicated that the age (OR = 1.053, P = 0.048), BMI (OR = 1.376, P = 0.004), meniscus root healing status (OR = 7.701, P = 0.005), HKA degree (OR = 1.891, P = 0.011) and preoperative symptom duration (OR = 1.055, P = 0.013) were the independent risk factors correlated with correction of MME. Additionally, the ROC curve demonstrated the cut-off values of the Age, BMI, HKA degree and preoperative symptom duration were 46.0 years, 22.5 kg/m2, 3.2° and 9.5 months, respectively, CONCLUSIONS: The arthroscopically assisted tendon graft anatomic reinforced reconstruction of the meniscal root showed clinical improvement and prevented the progression of postoperative MME. Additionally, younger patients, lower BMI, complete meniscus root healing, lower HKA degree and shorter preoperative symptom duration were the independent risk factors correlated with the good correction of MME in patients with repaired MMPRTs.

LEVEL OF EVIDENCE

Level IV.

Autologous semitendinosus meniscus graft significantly improves knee joint kinematics and the tibiofemoral contact after complete lateral meniscectomy

PURPOSE

The purpose of this study was to investigate the potential of a doubled semitendinosus (ST) and a single gracilis tendon (GT) lateral meniscus autograft to restore the knee joint kinematics and tibiofemoral contact after total lateral meniscectomy (LMM).

METHODS

Fourteen human knee joints were tested intact, after LMM and after ST and GT meniscus autograft treatment under an axial load of 200 N during full range of motion (0°-120°) and four randomised loading situations: without external moments, external rotation, valgus stress and a combination of external rotation and valgus stress using a knee joint simulator. Non-parametric statistical analyses were performed on joint kinematics and on the tibiofemoral contact mechanics.

RESULTS

LMM led to significant rotational instability of the knee joints (p < 0.02), which was significantly improved after ST autograft application (p < 0.04), except for knee joint flexions > 60°. The GT autograft failed to restore the joint kinematics. LMM significantly increased the tibiofemoral contact pressure (p < 0.03), while decreasing the contact area (p < 0.05). The ST autograft was able to restore the contact mechanics after LMM (p < 0.02), while the GT replacement displayed only an improvement trend.

CONCLUSION

The doubled ST lateral meniscus autograft improved the knee joint kinematics significantly and restored the tibiofemoral contact mechanics almost comparable to the native situation. Thus, from a biomechanical point of view, ST meniscus autografts might be a potential treatment alternative for patients who are indicated for meniscus allograft transplantation.

Medial meniscus posterior root tear reconstructed with gracilis autograft improve healing rate and patient reported outcome measures

BACKGROUND

Many surgeries have not reversed or prevented progressive symptomatic knee arthritis, and there is no consensus regarding the ideal repair or reconstruction technique for meniscal root treatment. Additionally, there is a lack of studies comparing the clinical efficacy evaluation of different repair techniques. The aim of the present study is to compare the clinical efficacy and healing rates of meniscus root in the treatment of medial meniscus posterior root tear (MMPRT) with the arthroscopically assisted meniscus root reconstruction with gracilis autograft and transtibial pull-out technique.

METHODS

Patients with MMPRT (type II) who received treatment of posterior meniscus root attachment point through the tibial tunnel between January 2018 and April 2019 were included in this study. Patients were divided into 2 groups (arthroscopically assisted gracilis autograft reconstruction technique: 29 cases; transtibial pull-out technique group: 35 cases) according to the different treatment methods. The mean follow-up period was 26.9 ± 2.3 months. The demographics, functional recovery of the knee, and meniscus root healing rates (assessed using knee magnetic resonance imaging (MRI) at the final follow-up) were compared between the two groups.

RESULTS

There was a statistically significant improvement in the Lysholm score, international knee documentation committee (IKDC) score, and visual analogue scale (VAS) score (P < 0.001 in both groups). Additionally, compared with the transtibial pull-out repair group, the arthroscopically assisted reconstruction with gracilis autograft showed significant improvement in the meniscus root healing rates, Lysholm score, and IKDC score at the end of follow-up (P < 0.05).

CONCLUSIONS

Compared with the transtibial pull-out technique, the arthroscopically assisted meniscus root reconstruction with gracilis autograft was advantageous for treating these patients with superior clinical outcome and higher meniscus root healing rates.

LEVEL OF EVIDENCE

Level III.

Arthroscopic Medial Meniscal Root Reconstruction With Gracilis Autograft Is Safe and Improves 2-Year Postoperative Patient-Reported Outcomes

Purpose

To describe patient-reported clinical outcomes and complications of anatomic medial meniscal root reconstruction with gracilis autograft.

Methods

Data on patients who underwent arthroscopic medial meniscal root reconstruction with gracilis autograft were prospectively collected between 2017 and 2021 and retrospectively reviewed. The inclusion criteria were symptomatic posterior medial meniscal LaPrade type 2 root tears with no more than Outerbridge grade 2 chondrosis of any knee compartment with a minimum follow-up period of 1 year. Patients with ligamentous instability and those with Workers’ Compensation status were excluded. Patient-reported outcomes (12-item Short Form Survey [SF-12], visual analog scale [VAS], Western Ontario and McMaster Universities Arthritis Index [WOMAC], and Lysholm scores) were collected prospectively and analyzed retrospectively and were scored and recorded both preoperatively and at postoperative intervals. Data were analyzed using cubic spline regression models. The study was approved by the University of South Carolina Institutional Review Board.

Results

A consecutive series of 27 patients treated by a single surgeon were evaluated. Twenty-one patients were included for data analysis (4 were excluded per criteria and 2 were lost to follow-up) with an average age of 48.1 years (range, 16-63 years). There were 18 female and 3 male patients. The average follow-up time was 25.2 months (range, 12-42 months). At the postoperative time points captured by the data examined, improvements in Lysholm, WOMAC, VAS, and SF-12 physical component summary scores were found to be statistically significant (P < .001, 95% confidence interval). Improvements in SF-12 mental component summary scores, however, did not reach the level of statistical significance (P = .262). Body mass index greater than 35 and age greater than 50 years were not found to be negative predictors of outcomes. Average patient-reported outcomes at 2 years’ follow-up improved from preoperatively as follows: Lysholm score, from 50 to 82.9; WOMAC score, from 53.9 to 87.4; and VAS score, from 5.1 to 1.2. No serious complications were observed.

Conclusions

Patients undergoing posterior medial meniscal root reconstruction showed statistically significant improvements in Lysholm, WOMAC, SF-12 physical component summary, and VAS scores but not SF-12 mental component summary scores at short-term follow-up. No serious complications or clinical failures occurred, and no patients required revision surgery.

Level of Evidence

Level IV, case series.

Meniscus repair: up-to-date advances in stem cell-based therapy

The meniscus is a semilunar fibrocartilage between the tibia and femur that is essential for the structural and functional integrity of the keen joint. In addition to pain and knee joint dysfunction, meniscus injuries can also lead to degenerative changes of the knee joint such as osteoarthritis, which further affect patient productivity and quality of life. However, with intrinsic avascular property, the tearing meniscus tends to be nonunion and the augmentation of post-injury meniscus repair has long time been a challenge. Stem cell-based therapy with potent regenerative properties has recently attracted much attention in repairing meniscus injuries, among which mesenchymal stem cells were most explored for their easy availability, trilineage differentiation potential, and immunomodulatory properties. Here, we summarize the advances and achievements in stem cell-based therapy for meniscus repair in the last 5 years. We also highlight the obstacles before their successful clinical translation and propose some perspectives for stem cell-based therapy in meniscus repair.

Mesenchymal Stem Cells From Different Sources in Meniscus Repair and Regeneration

Meniscus damage is a common trauma that often arises from sports injuries or menisci tissue degeneration. Current treatment methods focus on the repair, replacement, and regeneration of the meniscus to restore its original function. The advance of tissue engineering provides a novel approach to restore the unique structure of the meniscus. Recently, mesenchymal stem cells found in tissues including bone marrow, peripheral blood, fat, and articular cavity synovium have shown specific advantages in meniscus repair. Although various studies explore the use of stem cells in repairing meniscal injuries from different sources and demonstrate their potential for chondrogenic differentiation, their meniscal cartilage-forming properties are yet to be systematically compared. Therefore, this review aims to summarize and compare different sources of mesenchymal stem cells for meniscal repair and regeneration.

Arthroscopic Medial Meniscus Posterior Root Reconstruction and Pull-Out Repair Combined Technique for Root Tear of Medial Meniscus

Repair of medial meniscus posterior root tear is important in preventing rapid progression of knee osteoarthritis. There are many repair techniques for medial meniscus posterior root tears, and good clinical results have been reported. Conversely, in terms of improving extrusion and healing meniscal injuries, sufficient results have not been obtained. Reconstruction of the medial meniscus posterior root can restore meniscal hoop action and normal knee biomechanics. Moreover, pull-out repair technique provides strong traction. We describe arthroscopic medial meniscus posterior root reconstruction and pull-out repair technique combined technique for medial meniscus root tear.

Advances in the Mechanisms Affecting Meniscal Avascular Zone Repair and Therapies

Injuries to menisci are the most common disease among knee joint-related morbidities and cover a widespread population ranging from children and the general population to the old and athletes. Repair of the injuries in the meniscal avascular zone remains a significant challenge due to the limited intrinsic healing capacity compared to the peripheral vascularized zone. The current surgical strategies for avascular zone injuries remain insufficient to prevent the development of cartilage degeneration and the ultimate emergence of osteoarthritis (OA). Due to the drawbacks of current surgical methods, the research interest has been transferred toward facilitating meniscal avascular zone repair, where it is expected to maintain meniscal tissue integrity, prevent secondary cartilage degeneration and improve knee joint function, which is consistent with the current prevailing management idea to maintain the integrity of meniscal tissue whenever possible. Biological augmentations have emerged as an alternative to current surgical methods for meniscal avascular zone repair. However, understanding the specific biological mechanisms that affect meniscal avascular zone repair is critical for the development of novel and comprehensive biological augmentations. For this reason, this review firstly summarized the current surgical techniques, including meniscectomies and meniscal substitution. We then discuss the state-of-the-art biological mechanisms, including vascularization, inflammation, extracellular matrix degradation and cellular component that were associated with meniscal avascular zone healing and the advances in therapeutic strategies. Finally, perspectives for the future biological augmentations for meniscal avascular zone injuries will be given.

Biosynthetic scaffolds for partial meniscal loss: A systematic review from animal models to clinical practice

Acute or degenerative meniscus tears are the most common knee lesions. Meniscectomy provides symptomatic relief and functional recovery only in the short- to mid-term follow-up but significantly increases the risk of osteoarthritis. For this reason, preserving the meniscus is key, although it remains a challenge. Allograft transplants present many disadvantages, so during the last 20 years preclinical and clinical research focused on developing and investigating meniscal scaffolds. The aim of this systematic review was to collect and evaluate all the available evidence on biosynthetic scaffolds for meniscus regeneration both in vivo and in clinical studies. Three databases were searched: 46 in vivo preclinical studies and 30 clinical ones were found. Sixteen natural, 15 synthetic, and 15 hybrid scaffolds were studied in vivo. Among them, only 2 were translated into clinic: the Collagen Meniscus Implant, used in 11 studies, and the polyurethane-based scaffold Actifit®, applied in 19 studies. Although positive outcomes were described in the short- to mid-term, the number of concurrent procedures and the lack of randomized trials are the major limitations of the available clinical literature. Few in vivo studies also combined the use of cells or growth factors, but these augmentation strategies have not been applied in the clinical practice yet. Current solutions offer a significant but incomplete clinical improvement, and the regeneration potential is still unsatisfactory. Building upon the overall positive results of these “old” technologies to address partial meniscal loss, further innovation is urgently needed in this field to provide patients better joint sparing treatment options.

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Animal studies employed natural, synthetic and hybrid natural/synthetic scaffolds.

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Only in a few animal studies scaffold augmentation with cells or GFs was tested.

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Only two meniscal scaffolds have reached clinical application: CMI and Actifit.

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Clinical results are promising, but complete meniscus regeneration has not been achieved.

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There is urgent need for technological innovation in the field of meniscal regeneration.

Effect of atelocollagen on the healing status after medial meniscal root repair using the modified Mason-Allen stitch

INTRODUCTION

Addition of collagen during medial meniscal root repair (MMRR) may improve meniscal root healing minimising fibrous scar tissue formation. The purpose of this study was to verify the effect of atelocollagen on MMRR using the modified Mason-Allen stitch when compared with that of the conventional pullout repair by assessing the clinical and radiological outcomes.

HYPOTHESIS

It was hypothesised that atelocollagen would enhance the healing effect on the meniscal root following MMRR. Moreover, we presumed that MMRR with atelocollagen application might reduce meniscal extrusion by promoting healing.

MATERIALS AND METHODS

A total of 47 patients who underwent MMRR using the modified Mason-Allen stitch between 2015 and 2016 were included, and they were divided into group A (atelocollagen application; n=25) and group R (MMRR without atelocollagen application; n=22). The postoperative clinical outcomes, radiological outcomes, and meniscal root healing and medial compartment cartilage status on follow-up magnetic resonance imaging (MRI) were compared between the two groups.

RESULTS

Mean follow-up duration was 26.4±4.8 months in group A and 27.1±5.2 months in group R (p=0.598). Mean duration from surgery to follow-up MRI was 12.5±1.4 months in group A and 12.7±1.2 months in group R (p=0.604). The subjective knee scores improved significantly in both groups at the last follow-up (all, p<0.001). The Kellgren-Lawrence (K-L) grade progressed in 16% and 22.7% in group A and group R, respectively (p=0.351). Follow-up MRI showed progression of cartilage loss in the medial compartment in 28% and 40.9% in group A and group R, respectively (p=0.355). In terms of meniscal root healing, 18 (72%) and 12 (54.5%) patients had complete healing, and 6 (24%) and 8 (36.4%) patients had partial healing in groups A and R, respectively. The mean value of the intra-meniscal signal intensity (IMSI) of the meniscal root based on MRI in group A was significantly lower than that in group R (p<0.001). The medial meniscal extrusion in groups A and R decreased by 0.2±0.1mm and 0.1±0.3mm following MMRR without significant differences (p=0.056 and p=0.229, respectively). The IMSI presented significant negative correlations with the root healing status and significant positive correlations with K-L grade progression (p<0.05).

DISCUSSION

Atelocollagen application during MMRR yielded lower IMSIs, suggesting better healing, than did conventional pullout root repair. However, this technique could not demonstrate beneficial effects on meniscal extrusion.

LEVEL OF EVIDENCE

III, retrospective case-control study.

Anatomic Reinforced Medial Meniscal Root Reconstruction With Gracilis Autograft

Meniscal root tears, left untreated, result in accelerated progression of arthritis. Numerous techniques to repair medial meniscus posterior root tears have been presented in the literature. Direct repair of the meniscus to bone without reconstructive tissue may result in a nonanatomic and biologically weak construct with a significant number of structural repair failures. Re-creation of the ligament-like structures that fix the meniscal root to bone is critical to restoring normal knee biomechanics. We present an arthroscopic reconstructive technique using gracilis autograft with suture reinforcement for medial meniscus posterior root tears.

Native tissue-based strategies for meniscus repair and regeneration

Meniscus injuries appear to be becoming increasingly common and pose a challenge for orthopedic surgeons. However, there is no curative approach for dealing with defects in the inner meniscus region due to its avascular nature. Numerous strategies have been applied to regenerate and repair meniscus defects and native tissue-based strategies have received much attention. Native tissue usually has good biocompatibility, excellent mechanical properties and a suitable microenvironment for cellular growth, adhesion, redifferentiation, extracellular matrix deposition and remodeling. Classically, native tissue-based strategies for meniscus repair and regeneration are divided into autogenous and heterogeneous tissue transplantation. Autogenous tissue transplantation is performed more widely than heterogeneous tissue transplantation because there is no immunological rejection and the success rates are higher. This review first discusses the native meniscus structure and function and then focuses on the use of the autogenous tissue for meniscus repair and regeneration. Finally, it summarizes the advantages and disadvantages of heterogeneous tissue transplantation. We hope that this review provides some suggestions for the future design of meniscus repair and regeneration strategies.