Scaffold-based repair for cartilage healing: a systematic review and technical note

Atelocollagen-Induced Chondrogenesis Versus Microfracture Alone for Osteochondral Lesions of the Talus: Surgical Technique and a 1-Year Clinical Outcome Study

Osteochondral lesions of the talus (OLTs) are a common cause of post-traumatic ankle pain and disability. Atelocollagen-induced chondrogenesis (ACIC) aims to encourage the development of hyaline cartilage, which is biomechanically superior to fibrocartilage. This single-center, retrospective database study assessed patients who underwent arthroscopic microfracture with or without atelocollagen scaffold augmentation for OLT. Between 2010 and 2019, 87 patients underwent microfracture only and 31 patients underwent ACIC. Propensity score matching was used to match the ACIC group in a 1:2 ratio to a corresponding microfracture-only group using logistic regression. American Orthopaedic Foot & Ankle Society (AOFAS) scores, 100-mm Visual Analog Scale (VAS), Short Form-36 (SF-36), and satisfaction were assessed at preoperative, 3-, 6-, and 12-month intervals. There were no differences in baseline characteristics between groups after matching (P > .05). Both groups had similar improvements to VAS, AOFAS, and SF-36 scores up to 12 months (P > .05). Both groups had significant 1-year improvements to physical functioning, physical limitations in usual role activities, pain, and social functioning domains, but the ACIC group additionally had significant improvements to general health, vitality, and mental health. Patients in the ACIC group were also more satisfied than the microfracture group at all time points. Patients with OLTs who underwent ACIC reported superior satisfaction and improvements to quality of life, although clinical outcomes were similar to those who underwent microfracture alone at 1 year.Level of Evidence: Level III: Cohort study.

Human Osteoblasts' Response to Biomaterials for Subchondral Bone Regeneration in Standard and Aggressive Environments

Osteochondral lesions, when not properly treated, may evolve into osteoarthritis (OA), especially in the elderly population, where altered joint function and quality are usual. To date, a collagen/collagen-magnesium-hydroxyapatite (Col/Col-Mg-HAp) scaffold (OC) has demonstrated good clinical results, although suboptimal subchondral bone regeneration still limits its efficacy. This study was aimed at evaluating the in vitro osteogenic potential of this scaffold, functionalized with two different strategies: the addition of Bone Morphogenetic Protein-2 (BMP-2) and the incorporation of strontium (Sr)-ion-enriched amorphous calcium phosphate (Sr-ACP) granules. Human osteoblasts were seeded on the functionalized scaffolds (OC+BMP-2 and OC+Sr-ACP, compared to OC) under stress conditions reproduced with the addition of H2O2 to the culture system, as well as in normal conditions, and evaluated in terms of morphology, metabolic activity, gene expression, and matrix synthesis. The OC+BMP-2 scaffold supported a better osteoblast morphology and stimulated scaffold colonization, cell activity, and extracellular matrix secretion, especially in the stressed culture environment but also in normal culture conditions, with increased expression of genes related to osteoblast differentiation. In conclusion, the incorporation of BMP-2 into the Col/Col-Mg-HAp scaffold also represents an improvement of the osteochondral scaffold in more challenging conditions, supporting further preclinical studies to optimize it for use in clinical practice.

Treatment of Chondral Lesions in the Knee

Articular cartilage injuries are common and lead to early joint deterioration and osteoarthritis. Articular cartilage repair techniques aim at forming a cartilaginous neo-tissue to support the articular load and prevent progressive degeneration. Several techniques are available for this purpose, such as microfracture and chondrocyte transplantation. However, the procedural outcome is often fibrocartilage, which does not have the same mechanical resistance as cartilaginous tissue. Procedures with autologous osteochondral graft have a morbidity risk, and tissue availability limits their use. As such, larger lesions undergo osteochondral transplantation using fresh or frozen grafts. New techniques using minced or particulate cartilage fragments or mesenchymal stem cells are promising. This paper aims to update the procedures for treating chondral lesions of the knee.

Computational model of articular cartilage regeneration induced by scaffold implantation in vivo

Computational models allow to explain phenomena that cannot be observed through an animal model, such as the strain and stress states which can highly influence regeneration of the tissue. For this purpose, we have developed a simulation tool to determine the mechanical conditions provided by the polymeric scaffold. The computational model considered the articular cartilage, the subchondral bone, and the scaffold. All materials were modeled as poroelastic, and the cartilage had linear-elastic oriented collagen fibers. This model was able to explain the remodeling process that subchondral bone goes through, and how the scaffold allowed the conditions for cartilage regeneration. These results suggest that the use of scaffolds might lead the cartilaginous tissue growth in vivo by providing a better mechanical environment. Moreover, the developed computational model demonstrated to be useful as a tool prior experimental in vivo studies, by predicting the possible outcome of newly proposed treatments allowing to discard approaches that might not bring good results.

Gene Therapy for Regenerative Medicine

The development of biological methods over the past decade has stimulated great interest in the possibility to regenerate human tissues. Advances in stem cell research, gene therapy, and tissue engineering have accelerated the technology in tissue and organ regeneration. However, despite significant progress in this area, there are still several technical issues that must be addressed, especially in the clinical use of gene therapy. The aims of gene therapy include utilising cells to produce a suitable protein, silencing over-producing proteins, and genetically modifying and repairing cell functions that may affect disease conditions. While most current gene therapy clinical trials are based on cell- and viral-mediated approaches, non-viral gene transfection agents are emerging as potentially safe and effective in the treatment of a wide variety of genetic and acquired diseases. Gene therapy based on viral vectors may induce pathogenicity and immunogenicity. Therefore, significant efforts are being invested in non-viral vectors to enhance their efficiency to a level comparable to the viral vector. Non-viral technologies consist of plasmid-based expression systems containing a gene encoding, a therapeutic protein, and synthetic gene delivery systems. One possible approach to enhance non-viral vector ability or to be an alternative to viral vectors would be to use tissue engineering technology for regenerative medicine therapy. This review provides a critical view of gene therapy with a major focus on the development of regenerative medicine technologies to control the in vivo location and function of administered genes.

Scaffolds: a biomaterial engineering in targeted drug delivery for osteoporosis

Osteoporosis is an increasingly common condition that causes low bone density, porous bone, and increased fracture risk. Treatments for osteoporosis are divided into two categories: (a) antiresorptive and (b) anabolic. To decrease side effects of drug and dosage level variations caused by several consecutive administrations, various drug delivery systems have been proposed. Among them, scaffolds are one of the drug delivery systems that led to drug impart with high loading and suitable efficiency to specific sites which retain active agents at acceptable therapeutic levels. The purpose of this review was to explain the role of scaffolds in targeted drug delivery to bone tissue for the treatment of osteoporosis.

Clinical and Magnetic Resonance Imaging Outcomes After Microfracture Treatment With and Without Augmentation for Focal Chondral Lesions in the Knee: A Systematic Review and Meta-analysis

BACKGROUND

Focal cartilage lesions represent a common source of knee pain and disability, with the potential for the development and progression of osteoarthritis. Currently, microfracture (MFx) represents the most utilized first-line surgical treatment for small, focal chondral lesions. Recent investigations have examined methods of overcoming the limitations of MFx utilizing various augmentation techniques.

PURPOSE

To perform a systematic review and meta-analysis evaluating clinical and radiographic outcomes in patients undergoing isolated MFx versus MFx augmented with orthobiologics or scaffolds for focal chondral defects of the knee.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

A systematic review was performed to identify studies evaluating outcomes and adverse events in patients undergoing isolated MFx versus augmented MFx for focal chondral defects in the knee from 1945 to June 1, 2021. Data were extracted from each article that met the inclusion/exclusion criteria. Meta-analyses were performed for all outcomes reported in a minimum of 3 studies.

RESULTS

A total of 14 studies were identified, utilizing 7 different types of injectable augmentation regimens and 5 different scaffolding regimens. Across the 14 studies, a total of 744 patients were included. The mean patient age was 46.8 years (range, 34-58 years), and 58.3% (n = 434/744) of patients were women. The mean final follow-up time was 26.7 months (range, 12-60 months). The mean chondral defect size ranged from 1.3 to 4.8 cm². A post hoc analysis comparing mean improvement in postoperative outcomes scores compared with preoperative values found no significant differences in the improvement in the visual analog scale (VAS), International Knee Documentation Committee (IKDC), or Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores between patients undergoing isolated MFx and those undergoing MFx + augmentation. Patients undergoing MFx + augmentation reported significantly greater improvements in the Lysholm score and postoperative MOCART (magnetic resonance observation of cartilage repair tissue) scores compared with the isolated MFx group.

CONCLUSION

Patients undergoing combined MFx + augmentation reported significant improvements in mean Lysholm and MOCART scores, without significant improvements in VAS, IKDC, or WOMAC scores when compared with patients undergoing isolated MFx.

Mussel-inspired injectable chitosan hydrogel modified with catechol for cell adhesion and cartilage defect repair

Repairing articular cartilage defects is a great challenge due to the poor self-regenerative capability of cartilage. Hydrogel-based tissue engineering has been considered an effective strategy. In this study, inspired by mussel chemistry, catechol-modified chitosan (CS-C) hydrogel was prepared under the catalysis of horseradish peroxidase/hydrogen peroxide (HRP/H₂O₂) for cartilage defect repair in a rat model. The rheological and swelling properties and biodegradation behavior of the CS-C hydrogel were investigated. Besides, the chondrogenic effect of bone mesenchymal stem cells (BMSCs) within the CS-C hydrogel was also assessed in vitro. Moreover, after injecting in rat cartilage defects, the capability of cartilage repair of the BMSC-laden CS-C hydrogel was evaluated in vivo. The results showed that the rheological property, swelling property and biodegradation behavior of the CS-C hydrogel changed with the concentration of CS-C macromolecules. Besides, the CS-C hydrogel had good biocompatibility with BMSCs and could promote the proliferation and chondrogenic differentiation of BMSCs in vitro. As for cartilage defect repair in vivo, through the evaluation of gross observation and histology, the BMSC-laden CS-C hydrogel showed better reconstruction of hyaline cartilage than the untreated group and CS-C hydrogel only. Therefore, CS-C hydrogel laden with BMSC might be a promising strategy for repairing cartilage defects.

Cell-Free Scaffolds in Cartilage Knee Surgery: A Systematic Review and Meta-Analysis of Clinical Evidence

OBJECTIVE

To evaluate current evidence and results of cell-free scaffold techniques for knee chondral lesions.

DESIGN

A systematic review was conducted on 3 medical electronic databases according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, and the methodological quality was assessed with a modified Coleman Methodology Score. A meta-analysis was performed on the articles reporting results for visual analogue scale (VAS), Lysholm, and International Knee Documentation Committee (IKDC) scores. In order to investigate the clinical results improvement over time of cell-free cartilage scaffold implantation, all scores were reported and analyzed as improvement from basal scores at 1, 2, and ≥3 years' follow-up.

RESULTS

A total of 23 studies involving 521 patients were included in the qualitative data synthesis. The Coleman score showed an overall poor study quality with the majority of studies reporting results at short-/mid-term follow-up. Sixteen studies were included in the meta-analysis, showing a significant improvement from basal score at 1, 2, and ≥3 years' follow-up. The improvement reached at 1 year remained stable up to the last follow-up for all scores.

CONCLUSIONS

The current literature suggests that cell-free scaffolds may provide good clinical short-/mid-term results; however, the low evidence of the published studies and their short mean follow-up demand further evidence before more definitive conclusions can be drawn on their real potential over time and on their advantages and disadvantages compared to the cell-based strategies for the treatment of cartilage lesions.

Long-Term Evaluation of Allogenic Chondrocyte-Loaded PVA-PCL IPN Scaffolds for Articular Cartilage Repair in Rabbits

OBJECTIVE

This study tested the long-term efficacy of two synthetic scaffolds for osteochondral defects and compare the outcomes with that of an established technique that uses monolayer cultured chondrocytes in a rabbit model.

METHODS

Articular cartilage defect was created in both knees of 18 rabbits and divided into three groups of six in each. The defects in first group receiving cells loaded on Scaffold A (polyvinyl alcohol-polycaprolactone semi-interpenetrating polymer network (Monophasic, PVA-PCL semi-IPN), the second on Scaffold B (biphasic, PVA-PCL incorporated with bioglass as the lower layer), and the third group received chondrocytes alone. One animal from each group was sacrificed at 2 months and the rest at 1 year. O'Driscoll's score measured the quality of cartilage repair.

RESULTS

The histological outcome had good scores (22, 20, and 19) for all three groups at 2 months. At 1-year follow-up, the chondrocyte alone group had the best scores (mean 20.0 ± 1.4), while the group treated by PVA-PCL semi-IPN scaffolds fared better (mean 15 ± 4.2) than the group that received biphasic scaffolds (mean 11.8 ± 5.9). In all three groups, defects treated without cells scored less than the transplant.

CONCLUSION

These results indicate that while these scaffolds with chondrocytes perform well initially, their late outcome is disappointing. We propose that for all scaffold-based tissue repairs, a long-term evaluation should be mandatory. The slow degrading scaffolds need further modifications to improve the milieu for long-term growth of chondrocytes and their hyaline phenotype for the better incorporation of tissue-engineered constructs.

Arthroscopic microfracture with atelocollagen augmentation for osteochondral lesion of the talus: a multicenter randomized controlled trial

BACKGROUND

We aimed to evaluate whether arthroscopic microfracture with atelocollagen augmentation could improve the clinical outcomes and quality of regenerated cartilage in patients with osteochondral lesion of the talus (OLT). We hypothesized that the clinical outcomes and quality of the regenerated cartilage would be superior in patients undergoing arthroscopic microfracture with atelocollagen augmentation compared to those undergoing arthroscopic microfracture alone.

METHODS

In this multicenter, randomized controlled trial, 60 patients were randomly allocated to two groups: arthroscopic microfracture with atelocollagen augmentation (group 1, n = 31) and arthroscopic microfracture alone (group 2, n = 29). Mean 100-mm visual analog scale (VAS), Hannover scoring system (HSS), and American Orthopedic Foot and Ankle Society (AOFAS) scores were assessed 2 years postoperatively and compared between the groups. The quality of the regenerated cartilage was assessed according to the Magnetic Resonance Observation of CArtilage Repair Tissue (MOCART) score based on magnetic resonance imaging.

RESULTS

Forty-six patients (22 in group 1, 23 in group 2) completed the 2-year follow-up. The quality of the regenerated cartilage assessed based on the MOCART score was significantly superior in group 1 compared to group 2 (64.49 ± 18.27 vs 53.01 ± 12.14, p = 0.018). Clinical outcomes in terms of 100-mm VAS (17.25 ± 20.31 vs 19.37 ± 18.58, p = 0.72), HSS (93.09 ± 13.64 vs 86.09 ± 13.36, p = 0.14), and AOFAS (91.23 ± 8.62 vs 86.91 ± 10.68, p = 0.09) scores were superior in group 1 compared to group 2, but the differences were not statistically significant. Both groups showed significant improvements in clinical outcomes compared with the preoperative values.

CONCLUSION

The quality of the regenerated cartilage was superior after arthroscopic microfracture with atelocollagen augmentation compared to that after microfracture alone in patients with OLT. Clinical outcomes assessed 2 years postoperatively were superior in patients who underwent arthroscopic microfracture with atelocollagen augmentation compared to those who underwent arthroscopic microfracture alone, although the differences were not statistically significant. A long-term study of the cohort is required to confirm these findings.

TRIAL REGISTRATION

ClinicalTrials.gov ( NCT02519881 ), August 11, 2015.

Photocrosslinked natural hydrogel composed of hyaluronic acid and gelatin enhances cartilage regeneration of decellularized trachea matrix

Repair of long segmental trachea defects is always a great challenge in the clinic. The key to solving this problem is to develop an ideal trachea substitute with biological function. Using of a decellularized trachea matrix based on laser micropore technique (LDTM) demonstrated the possibility of preparing ideal trachea substitutes with tubular shape and satisfactory cartilage regeneration for tissue-engineered trachea regeneration. However, as a result of the very low cell adhesion of LDTM, an overly high concentration of seeding cell is required, which greatly restricts its clinical translation. To address this issue, the current study proposed a novel strategy using a photocrosslinked natural hydrogel (PNH) carrier to enhance cell retention efficiency and improve tracheal cartilage regeneration. Our results demonstrated that PNH underwent a rapid liquid-solid phase conversion under ultraviolet light. Moreover, the photo-generated aldehyde groups in PNH could rapidly react with inherent amino groups on LDTM surfaces to form imine bonds, which efficiently immobilized the cell-PNH composite to the surfaces of LDTM and/or maintained the composite in the LDTM micropores. Therefore, PNH significantly enhanced cell-seeding efficiency and achieved both stable cell retention and homogenous cell distribution throughout the LDTM. Moreover, PNH exhibited excellent biocompatibility and low cytotoxicity, and provided a natural three-dimensional biomimetic microenvironment to efficiently promote chondrocyte survival and proliferation, extracellular matrix production, and cartilage regeneration. Most importantly, at a relatively low cell-seeding concentration, homogeneous tubular cartilage was successfully regenerated with an accurate tracheal shape, sufficient mechanical strength, good elasticity, typical lacuna structure, and cartilage-specific extracellular matrix deposition. Our findings establish a versatile and efficient cell-seeding strategy for regeneration of various tissue and provide a satisfactory trachea substitute for repair and functional reconstruction of long segmental tracheal defects.

Long-term Results of Arthroscopic Matrix-Assisted Autologous Chondrocyte Transplantation: A Prospective Follow-up at 15 Years

BACKGROUND

Matrix-assisted autologous chondrocyte transplantation (MACT) procedures have been developed to overcome some of the limits of first-generation autologous chondrocyte implantation. However, while good autologous chondrocyte implantation results have been documented over time, data are scarce on the long-term MACT results.

PURPOSE

To evaluate long-term clinical results of a large cohort of patients treated with hyaluronic acid-based MACT for articular cartilage defects of the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A long-term evaluation of 113 patients was performed (91 men, 22 women; mean ± SD age, 29.0 ± 10.6 years) for 115 knees affected by chondral and osteochondral lesions of the femoral condyles and trochlea. Of these, 61 knees had undergone previous surgery, while other procedures were combined during the same operation in 48 knees. These patients were prospectively evaluated before surgery and at 2, 5, and 10 years after surgery, as well as at a final mean follow-up of 15 years (range, 12-18 years), with various clinical scores: International Knee Documentation Committee (IKDC), EuroQol visual analog scale (EQ-VAS), and Tegner. Both surgical and clinical failures were documented.

RESULTS

The IKDC subjective score increased from the basal level of 39.9 ± 14.6 (mean ± SD) to 77.3 ± 20.5 (P < .0005) at 2 years; results remained stable up to the 15-year follow-up (76.9 ± 20.5). EQ-VAS and Tegner scores showed a statistically significant improvement up to 10 years, with a further significant improvement at the final follow-up. A failure rate of 15.0% was documented, which increased to 21.7% when clinical failures were also considered. A worse outcome was found for older age (P < .0005), female sex (P = .002), degenerative lesions (P < .0005), longer duration of symptoms (P = .005), and previous surgery (P < .0005).

CONCLUSION

Arthroscopic MACT offered good and long-lasting results that were stable over time and resulted in a limited number of failures and reinterventions for up to 15 years of follow-up. Several factors were identified as having a prognostic value: a worse outcome could be expected in older patients, female patients, those affected by lesions with a degenerative cause, those having a longer duration of symptoms, and patients who underwent previous surgery.

Comparison of Chitosan-Based Liquid Scaffold and Hyaluronic Acid-Based Soft Scaffold for Treatment of Talus Osteochondral Lesions

BACKGROUND

The aim of this study was to evaluate the clinical and radiologic results of 2 different scaffolds with hyaluronan or chitosan-based structure used in the treatment of talus osteochondral lesions.

METHODS

Eighty-one patients who underwent chondral lesion repair with hyaluronan (n = 42) or chitosan-based (n = 39) scaffold were included. American Orthopaedic Foot & Ankle Society (AOFAS) and visual analog scale (VAS) scores were evaluated within and between groups preoperatively and at the 3rd, 12th, and 24th month postoperatively. In all patients, magnetic resonance imaging was performed between the 12 and 18th month postoperatively and compared with magnetic resonance observation of cartilage repair tissue (MOCART) scoring.

RESULTS

Within-group evaluations revealed significant improvements in AOFAS and VAS scores at postoperative 3 and 12 months. The postoperative 24th-month results of AOFAS scores in any group did not differ significantly from the 12th-month results. There was no significant difference between the groups in comparison of AOFAS, VAS, and MOCART scores at any time period.

CONCLUSION

Both scaffolds were found to be effective in cartilage healing but had no clinical or radiologic superiority to each other. This is the first study to compare the use of different cell-free scaffold types in osteochondral defects of the talus.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Cartilage Regeneration with Cell-free Type 1 Collagen Matrix - Past, Present and Future (Part 1 - Clinical Aspects)

Cartilage regeneration with cell-free matrices has developed from matrix-associated autologous cartilage cell transplantation (MACT) over ten years ago. Adjustments to the legal framework and higher hurdles for cell therapy have led to the procedures being established as an independent alternative to MACT. These procedures, which can be classified as matrix-induced autologous cartilage regeneration (MACR), all rely on the chemotactic stimulus of a cross-linked matrix, which mostly consists of collagens. Given the example of a commercially available type I collagen hydrogel, the state of clinical experience with MACR shall be summarized and an outlook on the development of the method shall be provided. It has been demonstrated in the clinical case series summarized here over the past few years that the use of the matrix is not only safe but also yields good clinical-functional and MR-tomographic results for both small (~ 10 mm) and large (> 10 mm) focal cartilage lesions. Depending on the size of the defect, MACR with a collagen type I matrix plays an important role as an alternative treatment method, in direct competition with both: microfracture and MACT.

Nano-porous anodic alumina: fundamentals and applications in tissue engineering

Recently, nanomaterials have been widely utilized in tissue engineering applications due to their unique properties such as the high surface to volume ratio and diversity of morphology and structure. However, most methods used for the fabrication of nanomaterials are rather complicated and costly. Among different nanomaterials, anodic aluminum oxide (AAO) is a great example of nanoporous structures that can easily be engineered by changing the electrolyte type, anodizing potential, current density, temperature, acid concentration and anodizing time. Nanoporous anodic alumina has often been used for mammalian cell culture, biofunctionalization, drug delivery, and biosensing by coating its surface with biocompatible materials. Despite its wide application in tissue engineering, thorough in vivo and in vitro studies of AAO are still required to enhance its biocompatibility and thereby pave the way for its application in tissue replacements. Recognizing this gap, this review article aims to highlight the biomedical potentials of AAO for applications in tissue replacements along with the mechanism of porous structure formation and pore characteristics in terms of fabrication parameters.

Reconstruction of Large Osteochondral Defects Using a Hemicondylar Aragonite-Based Implant in a Caprine Model

PURPOSE

To investigate the safety and regenerative potential of a hemicondylar aragonite-based scaffold in the reconstruction of large osteochondral lesions occupying an extensive portion of the medial femoral condyle in a goat model.

METHODS

Eight Saanen goats were treated by the implantation of an aragonite-based scaffold (size: 19 × 8 × 8 mm) on a previously prepared hemicondylar osteochondral defect located in the right medial femoral condyle of the knee. Goats were euthanized after 12 months and the specimens underwent X-ray imaging, macroscopic, micro-computed tomography, histology, and immunohistochemistry evaluations to assess subchondral bone and cartilage regeneration.

RESULTS

In all 8 goats, no adverse event or persistent inflammation was observed. The evaluations performed showed integration of the scaffold, which almost completely resorbed at 12 months. In all animals, no signs of osteoarthritis progression were seen. Concurrent regeneration of the osteochondral unit was observed, with trabecular bone tissue replacing the implant and restoring the subchondral layer, and the formation of an overlying hyaline cartilage surface, well integrated within the surrounding native tissue, also was observed.

CONCLUSIONS

The use of the hemicondylar biphasic aragonite-based implant in the treatment of osteochondral defects in the goat model proved to be technically feasible and safe. The scaffold degraded and was replaced by regenerated tissue within the 12-month study period, restoring the osteochondral unit both at the level of the cartilaginous layer and the subchondral bone.

CLINICAL RELEVANCE

The present animal study describes a scaffold-based procedure for the treatment of large condylar defects, which often require massive allograft or unicompartmental replacement. The aragonite-based implant promoted a regeneration of both cartilage and subchondral bone, and its use as a "biologic" unicondylar prosthesis might be feasible also in the clinical setting.

Microfractures Versus a Porcine-Derived Collagen-Augmented Chondrogenesis Technique for Treating Knee Cartilage Defects: A Multicenter Randomized Controlled Trial

PURPOSE

The purpose of this study was to evaluate the clinical efficacy and safety of treating patients with a cartilage defect of the knee with microfractures and porcine-derived collagen-augmented chondrogenesis technique (C-ACT).

METHODS

One hundred participants were randomly assigned to the control group (n = 48, microfracture) or the investigational group (n = 52, C-ACT). Clinical and magnetic resonance imaging (MRI) outcomes were assessed 12 and 24 months postoperatively for efficacy and adverse events. Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) assessment was used to analyze cartilage tissue repair. MRI outcomes for 50% defect filling and repaired tissue/reference cartilage (RT/RC) ratio were quantified using T2 mapping. Clinical outcomes were assessed using the visual analogue scale (VAS) for pain and 20% improvement, minimal clinically important difference (MCID), and patient acceptable symptom state for Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee score.

RESULTS

MOCART scores in the investigation group showed improved defect repair and filling (P = .0201), integration with the border zone (P = .0062), and effusion (P = .0079). MRI outcomes showed that the odds ratio (OR) for ≥50% defect filling at 12 months was statistically higher in the investigation group (OR 3.984, P = .0377). Moreover, the likelihood of the RT/RC OR becoming ≥1 was significantly higher (OR 11.37, P = .0126) in the investigation group. At 24 months postoperatively, the OR for the VAS 20% improvement rate was significantly higher in the investigational group (OR 2.808, P = .047). Twenty-three patients (52.3%) in the control group and 35 (77.8%) in the investigation group demonstrated more than the MCID of KOOS pain from baseline to 1 year postoperatively, with a significant difference between groups (P = .0116).

CONCLUSION

In this multicenter randomized trial, the addition of C-ACT resulted in better filling of cartilage defect of the knee joint.

LEVEL OF EVIDENCE

Level Ⅰ, Multicenter Randomized Controlled Trial.

The five year outcome of a clinical feasibility study using a biphasic construct with minced autologous cartilage to repair osteochondral defects in the knee

PURPOSE

Autologous minced cartilage has been used to repair cartilage defects. We have developed a biphasic cylindrical osteochondral construct for such use in human knees, and report the five year post-operative outcomes.

METHODS

Ten patients with symptomatic osteochondral lesion at femoral condyles were treated by replacing pathological tissue with the osteochondral composites, each consisted a _DL-poly-lactide-co-glycolide chondral phase and a _DL-poly-lactide-co-glycolide/β-tricalcium phosphate osseous phase. A flat chamber between the two phases served as a reservoir to house double-minced (mechanical pulverization and enzymatical dissociation) autologous cartilage graft. The osteochondral lesion was drill-fashioned a pit of identical dimensions as the construct. Graft-laden construct was press fit to the pit. Post-operative outcome was evaluated using Knee Injury and Osteoarthritis Outcome Score (KOOS) up to five years. Regenerated tissue was sampled with arthroscopic needle biopsy for histology at one year, and imaged with magnetic resonance at one, three, and five years to evaluate the neocartilage with MOCART chart. Subchondral bone integration was evaluated with computed tomography at three and five years.

RESULTS

Nine patients completed the five-year follow-up. Post-operative mean KOOS, except that of the "symptom" subscale, had been significantly higher than pre-operation from one year and maintained to five years. The change of MOCRAT scores of the regenerated cartilage paralleled the change of KOOS. The osseous phase remained mineralized during the five-year period, yet did not fully integrate with the host bone.

CONCLUSIONS

This novel construct for chondrocyte implantation yielded promising mid-term outcome. It repaired the osteochondral lesion with hyaline-like cartilage durable for at least five years.

Boron-assisted dual-crosslinked poly (γ-glutamic acid) hydrogels with high toughness for cartilage regeneration

Although mesenchymal stem cells (MSCs) encapsulated with bionic scaffolds have been widely used in treating trauma induced cartilage defects, challenges still persist for these hydrogel scaffolds to create suitable shelters for the MSCs and guide their behaviors. In this work, novel biomimetic hydrogel scaffolds were prepared by thiol-ene Michael addition between glycidyl methacrylate (GMA)-modified poly (γ-glutamic acid) (γ-PGA-GMA) and DL-1,4-Dithiothreitol (DTT) for cartilage tissue engineering. Sodium tetraborate decahydrate was added into the system to connect with DTT through hydrogen-bond interaction and served as catalyst for thiol-ene Michael addition to strengthen the intensity of the hydrogel. The hydrogels could be compressed to nearly a 90% strain, with 0.95 MPa compression stresses which was better than that of most hydrogels in mechanical property. Additionally, this hydrogel has other properties: fast and controlled gel-forming speed, adjustable swelling ration, suitable interior structure and so on. Above all, hydrogels have excellent cyto/tissue-compatibility. Cells cultured in hydrogels in vitro exhibited good proliferation and adhesion abilities and the hydrogels scaffolds contained stem cells immensely accelerated the regeneration of auricular cartilage of rabbits in vivo versus control group. The overall results approved that this bionic hydrogel may be a promising biomaterial for cartilage regeneration in the future.

Experimental Investigation and Optimal 3D Bioprinting Parameters of SA-Gel Porous Cartilage Scaffold

The main aim of this paper is to achieve the suitable SA-GEL (sodium alginate and gelatin) porous cartilage scaffold by 3D printing technology with optimal prediction parameters. Firstly, the characteristics of SA-GEL were analyzed, the influence of calcium chloride on the gel was explored, and the optimal cross-linking concentration and gelation temperature were determined. Secondly, a prediction model of the extrusion line width of SA-GEL was established, in which the printing pressure, the moving speed of the needle and the fiber interval were the important parameters affecting the printing performance of the SA-GEL composite material. Thirdly, the SA-GEL composite scaffolds were printed on the Bio-plotter platform, the C5.18 chondrocytes cells were cultured in the SA-GEL biomaterial scaffold, and the results show that the cells could survive well. These results show that, under the control of the printing parameters pressure 1.8 bar, moving speed 10.7 mm/s and the internal structure parameters of the scaffold is 0/45-1.2 (Printing interval: 1.2 mm, angle value: 45 degree), SA-GEL scaffold printing results can be obtained which have good mechanical properties and biocompatibility.

Dynamic Compressive Loading Improves Cartilage Repair in an In Vitro Model of Microfracture: Comparison of 2 Mechanical Loading Regimens on Simulated Microfracture Based on Fibrin Gel Scaffolds Encapsulating Connective Tissue Progenitor Cells

BACKGROUND

Microfracture of focal chondral defects often produces fibrocartilage, which inconsistently integrates with the surrounding native tissue and possesses inferior mechanical properties compared with hyaline cartilage. Mechanical loading modulates cartilage during development, but it remains unclear how loads produced in the course of postoperative rehabilitation affect the formation of the new fibrocartilaginous tissue.

PURPOSE

To assess the influence of different mechanical loading regimens, including dynamic compressive stress or rotational shear stress, on an in vitro model of microfracture repair based on fibrin gel scaffolds encapsulating connective tissue progenitor cells.

STUDY DESIGN

Controlled laboratory study.

METHODS

Cylindrical cores were made in bovine hyaline cartilage explants and filled with either (1) cartilage plug returned to original location (positive control), (2) fibrin gel (negative control), or (3) fibrin gel with encapsulated connective tissue progenitor cells (microfracture mimic). Constructs were then subjected to 1 of 3 loading regimens: (1) no loading (ie, unloaded), (2) dynamic compressive loading, or (3) rotational shear loading. On days 0, 7, 14, and 21, the integration strength between the outer chondral ring and the central insert was measured with an electroforce mechanical tester. The central core component, mimicking microfracture neotissue, was also analyzed for gene expression by real-time reverse-transcription polymerase chain reaction, glycosaminoglycan, and double-stranded DNA contents, and tissue morphology was analyzed histologically.

RESULTS

Integration strengths between the outer chondral ring and central neotissue of the cartilage plug and fibrin + cells groups significantly increased upon exposure to compressive loading compared with day 0 controls (P = .007). Compressive loading upregulated expression of chondrogenesis-associated genes (SRY-related HGMG box-containing gene 9 [SOX9], collagen type II α1 [COL2A1], and increased ratio of COL2A1 to collagen type I α1 [COL1A1], an indicator of more hyaline phenotype) in the neotissue of the fibrin + cells group compared with the unloaded group at day 21 (SOX9, P = .0032; COL2A1, P < .0001; COL2A1:COL1A1, P = .0308). Fibrin + cells constructs exposed to shear loading expressed higher levels of chondrogenic genes compared with the unloaded condition, but the levels were not as high as those for the compressive loading condition. Furthermore, catabolic markers (MMP3 and ADAMTS 5) were significantly upregulated by shear loading (P = .0234 and P < .0001, respectively) at day 21 compared with day 0.

CONCLUSION

Dynamic compressive loading enhanced neotissue chondrogenesis and maturation in a simulated in vitro model of microfracture, with generation of more hyaline-like cartilage and improved integration with the surrounding tissue.

CLINICAL RELEVANCE

Controlled loading after microfracture may be beneficial in promoting the formation of more hyaline-like cartilage repair tissue; however, the loading regimens applied in this in vitro model do not yet fully reproduce the complex loading patterns created during clinical rehabilitation. Further optimization of in vitro models of cartilage repair may ultimately inform rehabilitation protocols.

Clinical and radiographic outcomes of chitosan-glycerol phosphate/blood implant are similar with hyaluronic acid-based cell-free scaffold in the treatment of focal osteochondral lesions of the knee joint

PURPOSE

To determine the clinical and radiographic efficacy of chitosan-glycerol phosphate/blood implant versus hyaluronic acid-based cell-free scaffold in patients with focal osteochondral lesion of the knee joint.

METHODS

Clinical data of 46 patients surgically treated using either chitosan-glycerol phosphate/blood implant (25 patients, Group 1) or hyaluronic acid-based cell-free scaffold (21 patients, Group 2) in combination with microfracture were retrospectively evaluated. All lesions were Outerbridge grade III or IV with a mean lesion size of 3.3 ± 0.7 cm². The mean follow-up time was 24.4 months. Visual analogue scale (VAS), Lysholm knee score, and Tegner activity scale were the instruments to evaluate the clinical status. Magnetic resonance observation of cartilage repair tissue (MOCART) system was used to analyze the characteristics of repair tissue.

RESULTS

No significant differences were detected between the groups regarding VAS, Lysholm, and Tegner scores at any time interval during the whole follow-up. The mean post-operative VAS and Lysholm scores at the latest follow-up was significantly better in cases with the lesion size ≤ 3 cm² in Group 1 (p = 0.001, p < 0.001, respectively). However, no significant differences according to the lesion size were detected in Group 2 (n.s.). Complete repair with the filling of the defect was achieved in 7 (28%) of the knees in Group 1 and it was 7 (33.3%) of the knees in Group 2 according to MOCART system at the latest follow-up.

CONCLUSION

Single-stage regenerative cartilage surgery using chitosan-glycerol phosphate/blood implant combined to microfracture for focal osteochondral lesions of the knee revealed similar clinical and radiographic outcomes with hyaluronic acid-based cell-free scaffold at short-term follow-up. However, clinical outcomes of hyaluronan scaffold were less sensitive to defect size than chitosan. With the advantages of no hypertrophic repair tissue formation as well as no need to arthrotomy during surgery, chitosan is an effective choice especially in patients with the lesion size ≤ 3 cm².

LEVEL OF EVIDENCE

III.

Minimally Invasive and Regenerative Therapeutics

Advances in biomaterial synthesis and fabrication, stem cell biology, bioimaging, microsurgery procedures, and microscale technologies have made minimally invasive therapeutics a viable tool in regenerative medicine. Therapeutics, herein defined as cells, biomaterials, biomolecules, and their combinations, can be delivered in a minimally invasive way to regenerate different tissues in the body, such as bone, cartilage, pancreas, cardiac, skeletal muscle, liver, skin, and neural tissues. Sophisticated methods of tracking, sensing, and stimulation of therapeutics in vivo using nano-biomaterials and soft bioelectronic devices provide great opportunities to further develop minimally invasive and regenerative therapeutics (MIRET). In general, minimally invasive delivery methods offer high yield with low risk of complications and reduced costs compared to conventional delivery methods. Here, minimally invasive approaches for delivering regenerative therapeutics into the body are reviewed. The use of MIRET to treat different tissues and organs is described. Although some clinical trials have been performed using MIRET, it is hoped that such therapeutics find wider applications to treat patients. Finally, some future perspective and challenges for this emerging field are highlighted.

Reconstructing Bone with Natural Bone Graft: A Review of In Vivo Studies in Bone Defect Animal Model

Bone defects caused by fracture, disease or congenital defect remains a medically important problem to be solved. Bone tissue engineering (BTE) is a promising approach by providing scaffolds to guide and support the treatment of bone defects. However, the autologous bone graft has many defects such as limited sources and long surgical procedures. Therefore, xenograft bone graft is considered as one of the best substitutions and has been effectively used in clinical practice. Due to better preserved natural bone structure, suitable mechanical properties, low immunogenicity, good osteoinductivity and osteoconductivity in natural bone graft, decellularized and demineralized bone matrix (DBM) scaffolds were selected and discussed in the present review. In vivo animal models provide a complex physiological environment for understanding and evaluating material properties and provide important reference data for clinical trials. The purpose of this review is to outline the in vivo bone regeneration and remodeling capabilities of decellularized and DBM scaffolds in bone defect models to better evaluate the potential of these two types of scaffolds in BTE. Taking into account the limitations of the state-of-the-art technology, the results of the animal bone defect model also provide important information for future design of natural bone composite scaffolds.

StarPEG/heparin-hydrogel based in vivo engineering of stable bizonal cartilage with a calcified bottom layer

Repaired cartilage tissue lacks the typical zonal structure of healthy native cartilage needed for appropriate function. Current grafts for treatment of full thickness cartilage defects focus primarily on a nonzonal design and this may be a reason why inferior nonzonal regeneration tissue developed in vivo. No biomaterial-based solutions have been developed so far to induce a proper zonal architecture into a non-mineralized and a calcified cartilage layer. The objective was to grow bizonal cartilage with a calcified cartilage bottom zone wherein main tissue development is occurring in vivo. We hypothesized that starPEG/heparin-hydrogel owing to the glycosaminoglycan heparin contained as a building-block would prevent mineralization of the upper cartilage zone and be beneficial in inhibiting long-term progression of calcified cartilage into bone. MSCs were pre-cultured as self-assembling non-mineralized cell discs before a chondrocyte-seeded fibrin- or starPEG/heparin-hydrogel layer was cast on top directly before ectopic implantation. Bizonal cartilage with a calcified bottom-layer developed in vivo showing stronger mineralization compared to in vitro samples, but the hydrogel strongly determined outcome. Zonal fibrin-constructs lost volume and allowed non-organized expansion of collagen type X, ALP-activity and mineralization from the bottom-layer into upper regions, whereas zonal starPEG/heparin-constructs were of stable architecture. While non-zonal MSCs-derived discs formed bone over 12 weeks, the starPEG/heparin-chondrocyte layer prevented further progression of calcified cartilage into bone tissue. Conclusively, starPEG/heparin-hydrogel-controlled and cell-type mediated spatiotemporal regulation allowed in vivo growth of bizonal cartilage with a stable calcified cartilage layer. Altogether our work is an important milestone encouraging direct in vivo growth of organized cartilage after biofabrication.

Composite Cellularized Structures Created from an Interpenetrating Polymer Network Hydrogel Reinforced by a 3D Woven Scaffold

Biomaterial scaffolds play multiple roles in cartilage tissue engineering, including controlling architecture of newly formed tissue while facilitating growth of embedded cells and simultaneously providing functional properties to withstand the mechanical environment within the native joint. In particular, hydrogels-with high water content and desirable transport properties-while highly conducive to chondrogenesis, often lack functional mechanical properties. In this regard, interpenetrating polymer network (IPN) hydrogels can provide mechanical toughness greatly exceeding that of individual components; however, many IPN materials are not biocompatible for cell encapsulation. In this study, an agarose and poly(ethylene) glycol IPN hydrogel is seeded with human mesenchymal stem cells (MSCs). Results show high viability of MSCs within the IPN hydrogel, with improved mechanical properties compared to constructs comprised of individual components. These properties are further strengthened by integrating the hydrogel with a 3D woven structure. The resulting fiber-reinforced hydrogels display functional macroscopic mechanical properties mimicking those of native articular cartilage, while providing a local microenvironment that supports cellular viability and function. These findings suggest that a fiber-reinforced IPN hydrogel can support stem cell chondrogenesis while allowing for significantly enhanced, complex mechanical properties at multiple scales as compared to individual hydrogel or fiber components.

Lyophilized Scaffolds Fabricated from 3D-Printed Photocurable Natural Hydrogel for Cartilage Regeneration

Repair of cartilage defects is highly challenging in clinical treatment. Tissue engineering provides a promising approach for cartilage regeneration and repair. As a core component of tissue engineering, scaffolds have a crucial influence on cartilage regeneration, especially in immunocompetent large animal and human. Native polymers, such as gelatin and hyaluronic acid, have known as ideal biomimetic scaffold sources for cartilage regeneration. However, how to precisely control their structure, degradation rate, and mechanical properties suitable for cartilage regeneration remains a great challenge. To address these issues, a series of strategies were introduced in the current study to optimize the scaffold fabrication. First, gelatin and hyaluronic acid were prepared into a hydrogel and 3D printing was adopted to ensure precise control in both the outer 3D shape and internal pore structure. Second, methacrylic anhydride and a photoinitiator were introduced into the hydrogel system to make the material photocurable during 3D printing. Finally, lyophilization was used to further enhance mechanical properties and prolong degradation time. According to the current results, by integrating photocuring 3D printing and lyophilization techniques, gelatin and hyaluronic acid were successfully fabricated into human ear- and nose-shaped scaffolds, and both scaffolds achieved shape similarity levels over 90% compared with the original digital models. The scaffolds with 50% infill density achieved proper internal pore structure suitable for cell distribution, adhesion, and proliferation. Besides, lyophilization further enhanced mechanical strength of the 3D-printed hydrogel and slowed its degradation rate matching to cartilage regeneration. Most importantly, the scaffolds combined with chondrocytes successfully regenerated mature cartilage with typical lacunae structure and cartilage-specific extracellular matrixes both in vitro and in the autologous goat model. The current study established novel scaffold-fabricated strategies for native polymers and provided a novel natural 3D scaffold with satisfactory outer shape, pore structure, mechanical strength, degradation rate, and weak immunogenicity for cartilage regeneration.

Tailoring the Interface of Biomaterials to Design Effective Scaffolds

Tissue engineering (TE) is a multidisciplinary science, which including principles from material science, biology and medicine aims to develop biological substitutes to restore damaged tissues and organs. A major challenge in TE is the choice of suitable biomaterial to fabricate a scaffold that mimics native extracellular matrix guiding resident stem cells to regenerate the functional tissue. Ideally, the biomaterial should be tailored in order that the final scaffold would be (i) biodegradable to be gradually replaced by regenerating new tissue, (ii) mechanically similar to the tissue to regenerate, (iii) porous to allow cell growth as nutrient, oxygen and waste transport and (iv) bioactive to promote cell adhesion and differentiation. With this perspective, this review discusses the options and challenges facing biomaterial selection when a scaffold has to be designed. We highlight the possibilities in the final mold the materials should assume and the most effective techniques for its fabrication depending on the target tissue, including the alternatives to ameliorate its bioactivity. Furthermore, particular attention has been given to the influence that all these aspects have on resident cells considering the frontiers of materiobiology. In addition, a focus on chitosan as a versatile biomaterial for TE scaffold fabrication has been done, highlighting its latest advances in the literature on bone, skin, cartilage and cornea TE.

Patellofemoral Cartilage Repair

Purpose of Review

This review provides an overview of well-established and newly developed cartilage repair techniques for cartilage defects in the patellofemoral joint (PFJ). An algorithm will be presented for approaching cartilage defects considering the distinct anatomy of both the patellar and trochlear articular surfaces.

Recent Findings

Recent studies on cartilage repair in the PFJ have demonstrated improved outcomes in an attempt to delay or obviate the need for arthroplasty, and improve symptoms in young patients. While autologous chondrocyte implantation shows good and excellent outcomes for chondral lesions, osteochondral defects are adequately addressed with osteochondral allograft transplantation. In case of patellar malalignment, concomitant tibial tubercle osteotomy can significantly improve outcomes. Particulated cartilage and bone marrow aspirate concentrate are potential new alternative treatments for cartilage repair, currently in early clinical studies.

Summary

Due to the frequency of concomitant anatomic abnormalities in the PFJ, a thorough clinical examination combined with careful indication for each procedure in each individual patient combined with meticulous surgical technique is central to achieve satisfying outcomes. Additional comparative studies of cartilage repair procedures, as well as investigation of newer techniques, are needed.

[Preparation and in vitro evaluation of tissue engineered osteochondral integration of multi-layered scaffold]

Objective

The tissue engineered osteochondral integration of multi-layered scaffold was prepared and the related mechanical properties and biological properties were evaluated to provide a new technique and method for the repair and regeneration of osteochondral defect.

Methods

According to blend of different components and proportion of acellular cartilage extracellular matrix of pig, nano-hydroxyapatite, and alginate, the osteochondral integration of multi-layered scaffold was prepared by using freeze-drying and physical and chemical cross-linking technology. The cartilage layer was consisted of acellular cartilage extracellular matrix; the middle layer was consisted of acellular cartilage extracellular matrix and alginate; and the bone layer was consisted of nano-hydroxyapatite, alginate, and acellular cartilage extracellular matrix. The biological and mechanics characteristic of the osteochondral integration of multi-layered scaffold were evaluated by morphology observation, scanning electron microscope observation, Micro-CT observation, porosity and pore size determination, water absorption capacity determination, mechanical testing (compression modulus and layer adhesive strength), biocompatibility testing [L929 cell proliferation on scaffold assessed by MTT assay, and growth of green fluorescent protein (GFP)-labeled Sprague Dawley rats' bone marrow mesenchumal stem cells (BMSCs) on scaffolds].

Results

Gross observation and Micro-CT observation showed that the scaffolds were closely integrated with each other without obvious discontinuities and separation. Scanning electron microscope showed that the structure of the bone layer was relatively dense, while the structure of the middle layer and the cartilage layer was relatively loose. The pore structures in the layers were connected to each other and all had the multi-dimensional characteristics. The porosity of cartilage layer, middle layer, and bone layer of the scaffolds were 93.55%±2.90%, 93.55%±4.10%, and 50.28%±3.20%, respectively; the porosity of the bone layer was significantly lower than that of cartilage layer and middle layer ( P<0.05), but no significant difference was found between cartilage layer and middle layer ( P>0.05). The pore size of the three layers were (239.66±35.28), (153.24±19.78), and (82.72±16.94) μm, respectively, showing significant differences between layers ( P<0.05). The hydrophilic of the three layers were (15.14±3.15), (13.65±2.98), and (5.32±1.87) mL/g, respectively; the hydrophilic of the bone layer was significantly lower than that of cartilage layer and middle layer ( P<0.05), but no significant difference was found between cartilage layer and middle layer ( P>0.05). The compression modulus of the three layers were (51.36±13.25), (47.93±12.74), and (155.18±19.62) kPa, respectively; and compression modulus of the bone layer was significantly higher than that of cartilage layer and middle layer ( P<0.05), but no significant difference was found between cartilage layer and middle layer ( P>0.05). The osteochondral integration of multi-layered scaffold was tightly bonded with each layer. The layer adhesive strength between the cartilage layer and the middle layer was (18.21±5.16) kPa, and the layer adhesive strength between the middle layer and the bone layer was (16.73±6.38) kPa, showing no significant difference ( t=0.637, P=0.537). MTT assay showed that L929 cells grew well on the scaffolds, indicating no scaffold cytotoxicity. GFP-labeled rat BMSCs grew evenly on the scaffolds, indicating scaffold has excellent biocompatibility.

Conclusion

The advantages of three layers which have different performance of the tissue engineered osteochondral integration of multi-layered scaffold is achieved double biomimetics of structure and composition, lays a foundation for further research of animal in vivo experiment, meanwhile, as an advanced and potential strategy for osteochondral defect repair.

Autologous chondrocyte implantation in the knee: systematic review and economic evaluation

BACKGROUND

The surfaces of the bones in the knee are covered with articular cartilage, a rubber-like substance that is very smooth, allowing frictionless movement in the joint and acting as a shock absorber. The cells that form the cartilage are called chondrocytes. Natural cartilage is called hyaline cartilage. Articular cartilage has very little capacity for self-repair, so damage may be permanent. Various methods have been used to try to repair cartilage. Autologous chondrocyte implantation (ACI) involves laboratory culture of cartilage-producing cells from the knee and then implanting them into the chondral defect.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of ACI in chondral defects in the knee, compared with microfracture (MF).

DATA SOURCES

A broad search was done in MEDLINE, EMBASE, The Cochrane Library, NHS Economic Evaluation Database and Web of Science, for studies published since the last Health Technology Assessment review.

REVIEW METHODS

Systematic review of recent reviews, trials, long-term observational studies and economic evaluations of the use of ACI and MF for repairing symptomatic articular cartilage defects of the knee. A new economic model was constructed. Submissions from two manufacturers and the ACTIVE (Autologous Chondrocyte Transplantation/Implantation Versus Existing Treatment) trial group were reviewed. Survival analysis was based on long-term observational studies.

RESULTS

Four randomised controlled trials (RCTs) published since the last appraisal provided evidence on the efficacy of ACI. The SUMMIT (Superiority of Matrix-induced autologous chondrocyte implant versus Microfracture for Treatment of symptomatic articular cartilage defects) trial compared matrix-applied chondrocyte implantation (MACI^®) against MF. The TIG/ACT/01/2000 (TIG/ACT) trial compared ACI with characterised chondrocytes against MF. The ACTIVE trial compared several forms of ACI against standard treatments, mainly MF. In the SUMMIT trial, improvements in knee injury and osteoarthritis outcome scores (KOOSs), and the proportion of responders, were greater in the MACI group than in the MF group. In the TIG/ACT trial there was improvement in the KOOS at 60 months, but no difference between ACI and MF overall. Patients with onset of symptoms < 3 years' duration did better with ACI. Results from ACTIVE have not yet been published. Survival analysis suggests that long-term results are better with ACI than with MF. Economic modelling suggested that ACI was cost-effective compared with MF across a range of scenarios.

LIMITATIONS

The main limitation is the lack of RCT data beyond 5 years of follow-up. A second is that the techniques of ACI are evolving, so long-term data come from trials using forms of ACI that are now superseded. In the modelling, we therefore assumed that durability of cartilage repair as seen in studies of older forms of ACI could be applied in modelling of newer forms. A third is that the high list prices of chondrocytes are reduced by confidential discounting. The main research needs are for longer-term follow-up and for trials of the next generation of ACI.

CONCLUSIONS

The evidence base for ACI has improved since the last appraisal by the National Institute for Health and Care Excellence. In most analyses, the incremental cost-effectiveness ratios for ACI compared with MF appear to be within a range usually considered acceptable. Research is needed into long-term results of new forms of ACI.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014013083.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Treatment of Knee Osteochondritis Dissecans With a Cell-Free Biomimetic Osteochondral Scaffold: Clinical and Imaging Findings at Midterm Follow-up

BACKGROUND

Osteochondritis dissecans (OCD) is a developmental condition of subchondral bone that may result in secondary separation and instability of the overlying articular cartilage, which in turn may lead to degeneration of the overall joint and early osteoarthritis. Biphasic scaffolds have been developed to address defects of the entire osteochondral unit by reproducing the different biological and functional requirements and guiding the growth of both bone and cartilage.

PURPOSE

To evaluate midterm clinical and imaging results after cell-free osteochondral scaffold implantation for the treatment of knee OCD.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-seven patients (8 women, 19 men; mean age, 25.5 ± 7.7 years) were treated for knee OCD, with International Cartilage Repair Society (ICRS) grade 3 to 4 lesions with a mean size of 3.4 ± 2.2 cm² (range, 1.5-12 cm²), and prospectively evaluated for up to 5 years using the ICRS classification system and the Tegner score. Eighteen patients underwent magnetic resonance imaging (MRI) at 24 and 60 months of follow-up, and the graft was evaluated using the magnetic resonance observation of cartilage repair tissue (MOCART) score for the cartilage layer, while a specific score was used for subchondral bone.

RESULTS

All patients significantly improved their clinical scores at each follow-up until their final evaluation. The mean International Knee Documentation Committee (IKDC) subjective score improved from 48.4 ± 17.8 to 82.2 ± 12.2 at 2 years ( P < .0005), and it then remained stable for up to 5 years postoperatively (90.1 ± 12.0). The mean Tegner score increased from 2.4 ± 1.7 preoperatively to 4.4 ± 1.6 at 2 years ( P = .001), with a further increase up to 5.0 ± 1.7 at 5 years of follow-up ( P < .0005 vs preoperatively), reaching almost the preinjury level (5.7 ± 2.2). The MOCART score showed stable results between 24 and 60 months, whereas the subchondral bone status significantly improved over time. No correlation was found between MRI findings and clinical outcomes.

CONCLUSION

This 1-step cell-free scaffold implantation procedure showed good and stable results for up to 60 months of follow-up for the treatment of knee OCD. MRI showed abnormalities, in particular at the subchondral bone level, but there was an overall improvement of features over time. No correlation was found between imaging and clinical findings.

The Utility of Biologics, Osteotomy, and Cartilage Restoration in the Knee

The management of complex cartilage and meniscal pathology in young, athletic patients is extremely challenging. Joint preservation surgery is most difficult in patients with concomitant knee pathologies, including cartilage defects, meniscal deficiency, malalignment, and/or ligamentous insufficiency. Clinical decision making for these patients is further complicated by articular cartilage lesions, which often are incidental findings; therefore, treatment decisions must be based on the confirmed contribution of articular cartilage lesions to symptomatology. Surgical management of any of the aforementioned knee pathologies that is performed in isolation typically results in acceptable patient outcomes; however, concomitant procedures for the management of concomitant knee pathologies often are essential to the success of any single procedure. The use of biologic therapy as an alternative to or to augment more conventional surgical management has increased in popularity in the past decade, and indications for biologic therapy continue to evolve. Orthopaedic surgeons should understand knee joint preservation techniques, including biologic and reconstructive approaches in young, high-demand patients.

Scaffolds based therapy for osteochondral lesions of the talus: A systematic review

AIM

To clarify the effectiveness of scaffold-based therapy for osteochondral lesions of the talus (OLT).

METHODS

A systematic search of MEDLINE and EMBASE databases was performed during August 2016 and updated in January 2017. Included studies were evaluated with regard to the level of evidence (LOE) and quality of evidence (QOE) using the Modified Coleman Methodology Score. Variable reporting outcome data, clinical outcomes, and the percentage of patients who returned to sport at previous level were also evaluated.

RESULTS

Twenty-eight studies for a total of 897 ankles were included; 96% were either LOE III or IV. Studies were designated as either of poor or fair quality. There were 30 treatment groups reporting six different scaffold repair techniques: 13 matrix-induced autologous chondrocyte transplantation (MACT), nine bone marrow derived cell transplantation (BMDCT), four autologous matrix-induced chondrogeneis (AMIC), and four studies of other techniques. The categories of general demographics (93%) and patient-reported outcome data (85%) were well reported. Study design (73%), imaging data (73%), clinical variables (49%), and patient history (30%) were also included. The weighted mean American Orthopaedic Foot and Ankle Society (AOFAS) score at final follow-up was: 86.7 in MACT, 88.2 in BMDCT, and 82.3 in AMIC. Eight studies reported that a weighted mean of 68.3% of patients returned to a previous level of sport activity.

CONCLUSION

Scaffold-based therapy for OLT may produce favorable clinical outcomes, but low LOE, poor QOE, and variability of the data have confounded the effectiveness of this treatment.

Collagen Augmentation Improves the Quality of Cartilage Repair After Microfracture in Patients Undergoing High Tibial Osteotomy: A Randomized Controlled Trial

BACKGROUND

The quality of cartilage repair after marrow stimulation is unpredictable. To overcome the shortcomings of the microfracture technique, various augmentation techniques have been developed. However, their efficacies remain unclear.

HYPOTHESIS

The quality of cartilage repair and clinical outcomes would be superior in patients undergoing high tibial osteotomy (HTO) with microfracture and collagen augmentation compared to those undergoing HTO with microfracture alone without collagen augmentation for the treatment of medial compartment osteoarthritis (OA) of the knee.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Twenty-eight patients undergoing HTO were randomized into 2 groups: microfracture alone (group 1, n = 14) or microfracture with collagen augmentation (group 2, n = 14). At 1 year postoperatively, second-look arthroscopic surgery and biopsy of repaired cartilage were performed at the time of HTO plate removal. Biopsy specimens were graded using the International Cartilage Repair Society Visual Assessment Scale II (ICRS II). In addition, imaging outcomes in terms of the magnetic resonance observation of cartilage repair tissue (MOCART) score were assessed based on magnetic resonance imaging (MRI). Finally, clinical outcomes in terms of the visual analog scale (VAS) for pain score, Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, and Tegner activity scale score were evaluated.

RESULTS

The mean ICRS II score in group 2 was significantly higher than that in group 1 (1053.2 vs 885.4, respectively; P = .002). Group 2 showed greater improvement in tissue morphology, cell morphology, surface architecture, middle/deep zone assessment, and overall assessment compared with group 1 ( P < .050 for all comparisons). Imaging outcomes based on the MOCART score were superior in group 2 compared to those in group 1 on MRI at 1 year postoperatively (64.6 vs 45.4, respectively; P = .001). The degree of defect repair was better in group 2 than in group 1 ( P = .040). Clinical outcomes in terms of the VAS for pain score, KOOS, IKDC score, and Tegner activity scale score were improved in both groups without between-group differences ( P > .100 for all comparisons).

CONCLUSION

The quality of cartilage repair after microfracture with collagen augmentation was superior to that after microfracture alone in patients undergoing HTO. Clinical results after 1 year did not reflect this difference in tissue repair. Therefore, a longer follow-up of the cohort is needed to answer this question.

Terapias Celulares y Productos de Ingeniería de Tejidos para el Tratamiento de Lesiones Condrales de Rodilla

El cartílago articular es un tejido vulnerable a las lesiones de diferente etiología; siendo uno de los más afectados,  el cartílago de la rodilla. Aunque la mayoría de los tratamientos convencionales reducen los síntomas, generalmente conducen a la formación de fibrocartílago; el cual, posee características diferentes a las del cartílago hialino de las articulaciones.  Son pocas las aproximaciones terapéuticas que promueven el  reemplazo del tejido dañado por cartílago hialino funcional; las más exitosas son las denominadas terapias avanzadas, que aplican células y  productos de ingeniería de tejidos con el fin de estimular la regeneración del cartílago. La mayoría de ellas se basan en colocar soportes  hechos con biomateriales de diferente origen, que sembrados o no con células exógenas o endógenas, reemplazan al cartílago dañado y promueven su regeneración. Este  trabajo revisa algunas de las aproximaciones terapéuticas enfocadas en la regeneración del cartílago articular de rodilla; así como, los biomateriales más empleados en la elaboración de soportes para terapia celular e ingeniería de tejido cartilaginoso.

Host cell recruitment patterns by bone morphogenetic protein-2 releasing hyaluronic acid hydrogels in a mouse subcutaneous environment

Aim: This study aimed to identify host cell recruitment patterns in a mouse model in response to rhBMP-2 releasing hyaluronic acid hydrogels and influence of added nano-hydroxyapatite particles on rhBMP-2 release and pattern of bone formation. Materials & methods: Implanted gels were retrieved after implantation and cells were enzymatically dissociated for flow cytometric analysis. Percentages of macrophages, progenitor endothelial cells and putative mesenchymal stem cells were measured. Implants were evaluated for BMP-2 release by ELISA and by histology to monitor tissue formation. Results & conclusion: Hyaluronic acid+BMP-2 gels influenced the inflammatory response in the bone healing microenvironment. Host-derived putative mesenchymal stem cells were major contributors. Addition of hydroxyapatite nanoparticles modified the release pattern of rhBMP-2, resulting in enhanced bone formation.

Failure of Autologous Chondrocyte Implantation

Long-term results of autologous chondrocyte implantation and matrix-assisted autologous chondrocyte transplantation in the knee are satisfying, but not enough attention has been paid to the evaluation of failures. Thus, a systematic review of the literature was performed, underlining a failure rate in the 58 included articles of 14.9% among 4294 patients, most of them occurring in the first 5 years after surgery, and with no difference between autologous chondrocyte implantation and matrix-assisted autologous chondrocyte transplantation. Failures are very heterogenously defined in the current literature. A widely accepted definition is needed, and a comprehensive definition taking into consideration the patient's perception of the outcome, not just the surgeon's or researcher's point of view, would be advisable. Finally, there is no agreement on the most appropriate treatment of failures, and further studies are needed to give better indications to properly manage patients failed after cartilage procedures.

LEVEL OF EVIDENCE

Level IV.

Surgical treatments of cartilage defects of the knee: Systematic review of randomised controlled trials

BACKGROUND

The aim of this systematic review was to identify high quality randomised controlled trials (RCTs) and to provide an update on the most appropriate surgical treatments for knee cartilage defects.

METHODS

Two reviewers independently searched three databases for RCTs comparing at least two different treatment techniques for knee cartilage defects. The search strategy used terms mapped to relevant subject headings of MeSH terms. Strict inclusion and exclusion criteria were used to identify studies with patients aged between 18 and 55 years with articular cartilage defects sized between one and 15cm². Risk of bias was performed using a Coleman Methodology Score. Data extracted included patient demographics, defect characteristics, clinical outcomes, and failure rates.

RESULTS

Ten articles were included (861 patients). Eight studies compared microfracture to other treatment; four to autologous chondrocyte implantation (ACI) or matrix-induced ACI (MACI); three to osteochondral autologous transplantation (OAT); and one to BST-Cargel. Two studies reported better results with OAT than with microfracture and one reported similar results. Two studies reported superior results with cartilage regenerative techniques than with microfracture, and two reported similar results. At 10years significantly more failures occurred with microfracture compared to OAT and with OAT compared to ACI. Larger lesions (>4.5cm²) treated with cartilage regenerative techniques (ACI/MACI) had better outcomes than with microfracture.

CONCLUSIONS

Based on the evidence from this systematic review no single treatment can be recommended for the treatment of knee cartilage defects. This highlights the need for further RCTs, preferably patient-blinded, using an appropriate reference treatment or a placebo procedure.

Microfracture combined with functional pig peritoneum-derived acellular matrix for cartilage repair in rabbit models

Due to avascular and hypocellular nature of cartilage, repair of articular cartilage defects within synovial joints still poses a significant clinical challenge. To promote neocartilage properties, we established a functional scaffold named APM-E7 by conjugating a bone marrow-derived mesenchymal stem cell (BM-MSC) affinity peptide (E7) onto the acellular peritoneum matrix (APM). During in vitro culture, the APM-E7 scaffold can support better proliferation as well as better differentiation into chondrocytes of BM-MSCs. After implanting into cartilage defects in rabbits for 24weeks, compared with microfracture and APM groups, the APM-E7 scaffolds exhibited superior quality of neocartilage without transplant rejection, according to general observations, histological assessment, synovial fluid analysis, magnetic resonance imaging (MRI) and nanomechanical properties. This APM-E7 scaffold provided a scaffold for cell attachment, which was crucial for cartilage regeneration. Overall, the APM-E7 is a promising biomaterial with low immunogenicity for one-step cartilage repair by promoting autologous connective tissue progenitor (CTP) attachment.

STATEMENT OF SIGNIFICANCE

We report the one-step transplantation of functional acellular peritoneum matrix (APM-E7) with specific mesenchymal stem cell recruitment to repair rabbit cartilage injury. The experimental results illustrated that the APM-E7 scaffold was successfully fabricated, which could specifically recruit MSCs and fill the cartilage defects in the femoral trochlear of rabbits at 24weeks post-surgery. The repaired tissue was hyaline cartilage, which exhibited ideal mechanical stability. The APM-E7 biomaterial could provide scaffold for MSCs and improve cell homing, which are two key factors required for cartilage tissue engineering, thereby providing new insights into cartilage tissue engineering.