BST-CarGel® Treatment Maintains Cartilage Repair Superiority over Microfracture at 5 Years in a Multicenter Randomized Controlled Trial

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.

Two-Year Follow-Up and Remodeling Kinetics of ChonDux Hydrogel for Full-Thickness Cartilage Defect Repair in the Knee

OBJECTIVE

To determine performance and repair kinetics of the ChonDux hydrogel scaffold for treating focal articular cartilage defects in the knee over 24 months.

DESIGN

This assessor-blinded trial evaluates ChonDux hydrogel scaffold implantation in combination with microfracture in 18 patients across 6 sites. Male and female patients 18 to 65 years of age with full-thickness femoral condyle defects 2 to 4 cm² in area were enrolled. Eligible patients received ChonDux treatment followed by rehabilitation. Defect volume fill was evaluated after 3, 6 (primary outcome), 12, 18, and 24 months by assessor blinded magnetic resonance imaging (MRI) analysis. Secondary outcomes were T2-weighted MRI relaxation time and patient surveys via visual analogue scale (VAS) pain and International Knee Documentation Committee (IKDC) knee function scoring.

RESULTS

ChonDux maintained durable tissue restoration over 24 months with final defect percent fill of 94.2% ± 16.3% and no significant loss of fill volume at any time points. Tissues treated with ChonDux maintained T2 relaxation times similar to uninjured cartilage between 12 and 24 months. VAS pain scoring decreased between 1 and 6 weeks, and IKDC knee function scores improved by approximately 30.1 with ChonDux over 24 months.

CONCLUSION

ChonDux treatment is a safe adjunct to microfracture therapy and promotes stable restoration of full thickness articular cartilage defects for at least 24 months.

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.

Exquisite design of injectable Hydrogels in Cartilage Repair

Cartilage damage is still a threat to human beings, yet there is currently no treatment available to fully restore the function of cartilage. Recently, due to their unique structures and properties, injectable hydrogels have been widely studied and have exhibited high potential for applications in therapeutic areas, especially in cartilage repair. In this review, we briefly introduce the properties of cartilage, some articular cartilage injuries, and now available treatment strategies. Afterwards, we propose the functional and fundamental requirements of injectable hydrogels in cartilage tissue engineering, as well as the main advantages of injectable hydrogels as a therapy for cartilage damage, including strong plasticity and excellent biocompatibility. Moreover, we comprehensively summarize the polymers, cells, and bioactive molecules regularly used in the fabrication of injectable hydrogels, with two kinds of gelation, i.e., physical and chemical crosslinking, which ensure the excellent design of injectable hydrogels for cartilage repair. We also include novel hybrid injectable hydrogels combined with nanoparticles. Finally, we conclude with the advances of this clinical application and the challenges of injectable hydrogels used in cartilage repair.

Autologous Fractionated Adipose Tissue as a Natural Biomaterial and Novel One-Step Stem Cell Therapy for Repairing Articular Cartilage Defects

Articular cartilage damage remains a tough challenge for clinicians. Stem cells have emerged promising biologics in regenerative medicine. Previous research has widely demonstrated that adipose-derived mesenchymal stem cells (ADSCs) can promote cartilage repair due to their multipotency. However, enzymatic isolation and monolayer expansion of ADSCs decrease their differentiation potential and limit their clinical application. Here, a novel adipose tissue-derived product, extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel), was obtained by simple mechanical shifting and centrifugation to separate the fat oil and concentrate the effective constituents. This study aimed to evaluate the therapeutic effect of this natural biomaterial on the repair of articular cartilage defects. Scanning electron microscopy showed that the fibrous structure in the ECM/SVF-gel was preserved. ADSCs sprouted from the ECM/SVF-gel were characterized by their ability of differentiation into chondrocytes, osteoblasts, and adipocytes. In a rabbit model, critical-sized cartilage defects (diameter, 4 mm; depth, 1.5 mm) were created and treated with microfracture (MF) or a combination of autologous ECM/SVF-gel injection. The knee joints were evaluated at 6 and 12 weeks through magnetic resonance imaging, macroscopic observation, histology, and immunohistochemistry. The International Cartilage Repair Society score and histological score were significantly higher in the ECM/SVF-gel group than those in the MF-treated group. The ECM/SVF-gel distinctly improved cartilage regeneration, integration with surrounding normal cartilage, and the expression of hyaline cartilage marker, type II collagen, in comparison with the MF treatment alone. Overall, the ready-to-use ECM/SVF-gel is a promising therapeutic strategy to facilitate articular cartilage regeneration. Moreover, due to the simple, time-sparing, cost-effective, enzyme-free, and minimally invasive preparation process, this gel provides a valuable alternative to stem cell-based therapy for clinical translation.

Effect of autologous adipose-derived mesenchymal stem cell therapy in the treatment of an osteochondral lesion of the ankle

Osteochondral lesions (OCLs) of the talus are rare but can be associated with significant morbidity and may lead to the development of osteoarthritis. An improved understanding of the action of mesenchymal stem cells (MSCs) has seen renewed interest in their role in cartilage repair, with early preclinical and clinical research showing benefits in symptomatic and structural improvement. A 42-year-old man presented with an unstable OCL of the talus and onset of early osteoarthritis with a history of multiple previous ankle arthroscopies for ankle impingement. The patient underwent arthroscopic removal of the OCL in combination with adipose-derived MSC therapy. The patient reported progressive improvement as measured by the validated Foot and Ankle Disability Index. Repeat MRI with additional T2 mapping techniques showed successful regeneration of hyaline-like cartilage. This case is the first to show the successful use of MSC therapy in the management of an ankle OCL. Trial registration: Australian New Zealand Clinical Trials Registry - ACTRN12617000638336.

Better Clinicoradiological Results of BST-CarGel Treatment in Cartilage Repair Compared With Microfracture in Acetabular Chondral Defects at 2 Years

BACKGROUND

BST-CarGel (CarGel) is an injectable chitosan scaffold that is mixed with fresh, autologous blood and injected into the site of microfracture (MF) to physically stabilize clots and enhance cartilage repair.

PURPOSE

To evaluate short-term clinicoradiological outcomes of patients treated arthroscopically for acetabular chondral defects with CarGel in conjunction with MF compared with those treated with MF alone.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All patients who underwent hip arthroscopy and received MF with or without CarGel for acetabular chondral defects between 2014 and 2018 with a minimum 2-year clinicoradiological follow-up were included. Intraoperative details, postoperative complications, and clinical outcome scores, including the international Hip Outcome Tool-33 (iHOT-33), Hip Outcome Score (HOS)-Activities of Daily Living (HOS-ADL), and Hip Outcome Score-Sports Profile, were analyzed. Serial plain radiographs were assessed independently by 2 blinded observers. A survival analysis was performed to identify the number of cases converted to total hip arthroplasty (THA) in both groups, which was correlated with the cartilage defect size at the time of surgery.

RESULTS

Eighty patients (54 CarGel and 26 MF) were evaluated, including 56 men (70%) and 48 right hips (60%). Three patients were lost to follow-up. There were no major adverse events in either group. The average defect size was 3.63 and 4.97 cm² in MF and CarGel, respectively (P = .002). There was a statistically significant improvement in iHOT-33 (from 43.24 to 60.17 in MF and from 41.13 to 58.39 in CarGel) and HOS-ADL (from 62.25 to 76.75 in MF and from 44.69 to 79.16 in CarGel) scores. There was no difference between the 2 groups in the outcome scores after adjusting for covariates. Survival analysis showed 34.6% of MF cases and 5.9% of CarGel cases were converted to THA (P = .001). The mean defect size of the failure group was higher in CarGel than in MF (8.83 and 3.72 cm², respectively). Mean joint space reduction was 1.41 mm in MF and 0.19 mm in CarGel (P < .001).

CONCLUSION

Two-year clinicoradiological results were promising in these lesions that are difficult to treat. Arthroscopic treatment of chondral acetabular defects with CarGel demonstrated a significant decrease in progressive loss of joint space and conversion to THA compared with MF as an isolated procedure.

The effects of small-needle-knife therapy on pain and mobility from knee osteoarthritis: a pilot randomized-controlled study

OBJECTIVE

To investigate the effect of small needle-knife therapy in people with painful knee osteoarthritis.

DESIGN

Pilot randomised, controlled trial.

SETTING

Rehabilitation hospital.

SUBJECTS

In-patients with osteo-arthritis of the knee.

INTERVENTIONS

Either 1 to 3 small needle-knife treatments over seven days or oral Celecoxib. All patients stayed in hospital three weeks, receiving the same mobility-focused rehabilitation.

MEASURES

Oxford Knee Score (OKS), gait speed and kinematics were recorded at baseline, at three weeks (discharge) and at three-months (OKS only). Withdrawal from the study, and adverse events associated with the small needle knife therapy were recorded.

RESULTS

83 patients were randomized: 44 into the control group, of whom 10 were lost by three weeks and 12 at 3 months; 39 into the experimental group of whom eight were lost at three weeks and three months. The mean (SE) OKS scores at baseline were Control 35.86 (1.05), Exp 38.38 (0.99); at three weeks 26.64 (0.97) and 21.94 (1.23); and at three months 25.83 (0.91) and 20.48 (1.14) The mean (SE) gait speed at baseline was 1.07 (0.03) m/sec (Control) and 0.98 (0.03), and at three weeks was 1.14 (0.03) and 1.12 (0.03) (P < 0.05). Linear mixed model statistical analysis showed that the improvements in the experimental group were statistically significant for total OKS score at discharge and three months.

CONCLUSIONS

Small needle-knife therapy added to standard therapy for patients with knee osteoarthritis, was acceptable, safe and reduced pain and improved global function on the Oxford Knee Score. Further research is warranted.

CARGEL Bioscaffold improves cartilage repair tissue after bone marrow stimulation in a minipig model

Purpose

To gain knowledge of the repair tissue in critically sized cartilage defects using bone marrow stimulation combined with CARGEL Bioscaffold (CB) compared with bone marrow stimulation (BMS) alone in a validated animal model.

Methods

Six adult Göttingen minipigs received two chondral defects in each knee. The knees were randomized to either BMS combined with CB or BMS alone. The animals were euthanized after 6 months. Follow-up consisted of histomorphometry, immunohistochemistry, semiquantitative scoring of the repair tissue (ICRS II), and μCT of the trabecular bone beneath the defect.

Results

There was significantly more fibrocartilage (80% vs 64%, p = 0.04) and a trend towards less fibrous tissue (15% vs 30%, p = 0.05) in the defects treated with CB. Hyaline cartilage was only seen in one defect treated with CB and none treated with BMS alone.

For histological semiquantitative score (ICRS II), defects treated with CB scored lower on subchondral bone (69 vs. 44, p = 0.04). No significant differences were seen on the other parameters of the ICRS II. Immunohistochemistry revealed a trend towards more positive staining for collagen type II in the CB group (p = 0.08). μCT demonstrated thicker trabeculae (p = 0.029) and a higher bone material density (p = 0.028) in defects treated with CB.

Conclusion

Treatment of cartilage injuries with CARGEL Bioscaffold seems to lead to an improved repair tissue and a more pronounced subchondral bone response compared with bone marrow stimulation alone. However, the CARGEL Bioscaffold treatment did not lead to formation of hyaline cartilage.

Current solutions for the treatment of chronic articular cartilage defects in the knee

Chondral and osteochondral defects in the knee are common and may lead to degenerative joint disease if treated inappropriately.

Conventional treatments such as microfracture often result in fibrocartilage formation and are associated with inferior results. Additionally, microfracture is generally unsuitable for the treatment of defects larger than 2–4 cm².

The osteochondral autograft transfer system (OATS) has been shown to produce superior clinical outcomes to microfracture but is technically difficult and may be associated with donor-site morbidity. Osteochondral allograft use is limited by graft availability and failure of cartilage incorporation is an issue.

Autologous chondrocyte implantation (ACI) has been shown to result in repair with hyaline-like cartilage but involves a two-stage procedure and is relatively expensive.

Rehabilitation after ACI takes 12 months, which is inconvenient and not feasible for athletic patients.

Newer methods to regenerate cartilage include autologous stem cell transplantation, which may be performed as a single-stage procedure, can have a shorter rehabilitation period and is less expensive than ACI. Longer-term studies of these methods are needed.

Cite this article: EFORT Open Rev 2020;5:156-163. DOI: 10.1302/2058-5241.5.190031

Surgical Techniques for Knee Cartilage Repair: An Updated Large-Scale Systematic Review and Network Meta-analysis of Randomized Controlled Trials

PURPOSE

The aim of this study was to investigate the most appropriate surgical interventions for patients with knee articular cartilage defects from the level I randomized clinical trials.

METHODS

We searched five databases for level I randomized clinical trials. Treatments were compared if reported in more than one study using network meta-analysis to boost the number of included studies per comparison.

RESULTS

We studied 21 articles that included 891 patients. Traumatic lesion was the most common cause in the included patients. There were significantly higher failure rates in the microfracture (MF) group compared to autologous chondrocyte implantation (ACI) group at 10-year follow-up. Moreover, osteochondral autograft transplantation (OAT) showed significantly more excellent or good results at > 3-year follow-up compared to MF, whereas MF showed significantly more poor results versus ACI and matrix-induced autologous chondrocyte implantation (MACI). Furthermore, OAT showed significantly more poor results than MACI at 1-year follow-up. Similarly, patients who underwent OAT had higher return-to-activity rates than those with MF. It is noteworthy that the Knee injury and Osteoarthritis Outcome Score was higher in patients who underwent characterized chondrocyte implantation or MACI compared to MF. Finally, there were no significant differences among the various interventions regarding reintervention, biopsy types or adverse events. According to the P scores for interventions ranking, there was a disagreement concerning the best intervention; however, MF was always ranked as the last.

CONCLUSIONS

Cartilage repair techniques, rather than MF, provide higher quality repair of tissue and have lower failure and higher return-to-activity rates. Moreover, OAT had significantly more excellent or good results compared to MF, whereas MF had significantly more poor results than ACI and MACI. Future studies need to have longer follow-up periods and more representative populations to investigate the efficacy and safety of these interventions.

LEVEL OF EVIDENCE

Level I: meta-analysis of Level I studies.

In-Situ Forming pH and Thermosensitive Injectable Hydrogels to Stimulate Angiogenesis: Potential Candidates for Fast Bone Regeneration Applications

Biomaterials that promote angiogenesis are required for repair and regeneration of bone. In-situ formed injectable hydrogels functionalised with bioactive agents, facilitating angiogenesis have high demand for bone regeneration. In this study, pH and thermosensitive hydrogels based on chitosan (CS) and hydroxyapatite (HA) composite materials loaded with heparin (Hep) were investigated for their pro-angiogenic potential. Hydrogel formulations with varying Hep concentrations were prepared by sol-gel technique for these homogeneous solutions were neutralised with sodium bicarbonate (NaHCO3) at 4 °C. Solutions (CS/HA/Hep) constituted hydrogels setting at 37 °C which was initiated from surface in 5-10 minutes. Hydrogels were characterised by performing injectability, gelation, rheology, morphology, chemical and biological analyses. Hydrogel solutions facilitated manual dropwise injection from 21 Gauge which is highly used for orthopaedic and dental administrations, and the maximum injection force measured through 19 G needle (17.191 ± 2.296N) was convenient for manual injections. Angiogenesis tests were performed by an ex-ovo chick chorioallantoic membrane (CAM) assay by applying injectable solutions on CAM, which produced in situ hydrogels. Hydrogels induced microvascularity in CAM assay this was confirmed by histology analyses. Hydrogels with lower concentration of Hep showed more efficiency in pro-angiogenic response. Thereof, novel injectable hydrogels inducing angiogenesis (CS/HA/Hep) are potential candidates for bone regeneration and drug delivery applications.

Therapeutic effects and adaptive limits of an acellular technique by ultrapurified alginate (UPAL) gel implantation in canine osteochondral defect models

Background

The aim of this study was to clarify the objective therapeutic effects of an acellular technique by ultrapurified alginate (UPAL) gel implantation in canine osteochondral defect models.

Methods

Two osteochondral defects (diameters: 3.0 and 5.0 mm) were created on each patellar groove in both knees of 10 dogs. Defects were divided into four groups (n = 10 each): Group 1, untreated 3.0-mm defect; Group 2, 3.0-mm defect with UPAL gel; Group 3, untreated 5.0-mm defect; and Group 4, 5.0-mm defect with UPAL gel. All surgical procedures were performed by individuals unfamiliar with the technique at an independent institution. Articular surfaces were evaluated grossly and histologically at 27 weeks after operation.

Results

UPAL gel-treated osteochondral defects showed significantly improved gross appearance in Group 4 and histological appearance in Groups 2 and 4. Reparative tissues in the 3.0-mm defect with UPAL gel were replaced by hyaline-like cartilage tissue. The 5.0-mm defects with UPAL gel were mostly covered with fibrocartilaginous tissue, whereas UPAL gel-untreated defects mostly remained uncovered by any tissue.

Conclusions

Although an acellular technique using UPAL gel implantation significantly enhanced osteochondral repair in canines, reparative tissues of the large defect with alginate gel comprised of fibrocartilaginous tissue. This surgical technique is effective, especially for small cartilage injuries. Further improvements are required before clinical application in cases of severe osteochondral defects in humans.

Current Development on Chitosan-based Antimicrobial Drug Formulations for the Wound Healing

BACKGROUND

Derived from polyose, chitosan is an outstanding natural linear polysaccharide comprised of random arrangement of β-(1-4)-linked D-Glucosamine and N-acetyl-DGlucosamine units.

OBJECTIVE

Researchers have been using chitosan as a network forming or gelling agent with economically available, present polyose, low immunogenicity, biocompatibility, non-toxicity, biodegradability, protects against secretion from irritation and don't suffer the danger of transmission animal infective agent.

METHODS

Furthermore, recent studies gear up the chitosan used in the development of various biopharmaceutical formulations, including nanoparticles, hydrogels, implants, films, fibers, etc. Results: These formulations produce potential activities as antimicrobials, cancer treatment, medical aid, and wound healing, controlled unleash device or drug trigger retarding device and 3DBiomedical sponge, etc. Conclusion: The present article discusses the development of various drug formulations utilizing chitosan as biopolymers for the repairing of broken tissues and healing in case of wound infection.

Preliminary evaluation of an osteochondral autograft, a prosthetic implant, and a biphasic absorbable implant for osteochondral reconstruction in a sheep model

OBJECTIVE

To determine the ability of three implants to enhance the healing of osteochondral defects: (1) a biphasic construct composed of calcium phosphate (CaP) and chitosan/cellulosic polymer, (2) a titanium-polyurethane implant, and (3) an osteochondral autograft.

STUDY DESIGN

Experimental study.

ANIMALS

Ten adult female sheep.

METHODS

In five sheep, an 8-mm diameter osteochondral defect was created on the medial femoral condyle of a stifle and filled with a synthetic titanium-polyurethane implant. In five sheep, a similar defect was filled with an osteochondral autograft, and the donor site was filled with a biphasic construct combining CaP granules and a chitosan/cellulosic polymer. Sheep were monitored daily for lameness. Stifle radiographs and MRI were evaluated at 20 weeks, prior to animals being humanely killed. Surgical sites were evaluated with histology, microcomputed tomography, and scanning electron microscopy.

RESULTS

Clinical outcomes were satisfactory regardless of the tested biomaterials. All implants appeared in place on imaging studies. Osteointegration of prosthetic implants varied between sites, with limited ingrowth of new bone into the titanium structure. Autografts and biphasic constructs were consistently well integrated in subchondral bone. All autografts except one contained a cartilage surface, and all biphasic constructs except one partially restored hyaline cartilage surface.

CONCLUSION

Biphasic constructs supported hyaline cartilage and subchondral bone regeneration, although restoration of the articular cartilage was incomplete.

CLINICAL IMPACT

Biphasic constructs may provide an alternative treatment for osteochondral defects, offering a less invasive approach compared with autologous grafts and eliminating the requirement for a prosthetic implant.

Chitosan as a Wound Dressing Starting Material: Antimicrobial Properties and Mode of Action

Fighting bacterial resistance is one of the concerns in modern days, as antibiotics remain the main resource of bacterial control. Data shows that for every antibiotic developed, there is a microorganism that becomes resistant to it. Natural polymers, as the source of antibacterial agents, offer a new way to fight bacterial infection. The advantage over conventional synthetic antibiotics is that natural antimicrobial agents are biocompatible, non-toxic, and inexpensive. Chitosan is one of the natural polymers that represent a very promising source for the development of antimicrobial agents. In addition, chitosan is biodegradable, non-toxic, and most importantly, promotes wound healing, features that makes it suitable as a starting material for wound dressings. This paper reviews the antimicrobial properties of chitosan and describes the mechanisms of action toward microbial cells as well as the interactions with mammalian cells in terms of wound healing process. Finally, the applications of chitosan as a wound-dressing material are discussed along with the current status of chitosan-based wound dressings existing on the market.

Surgical and tissue engineering strategies for articular cartilage and meniscus repair

Injuries to articular cartilage and menisci can lead to cartilage degeneration that ultimately results in arthritis. Different forms of arthritis affect ~50 million people in the USA alone, and it is therefore crucial to identify methods that will halt or slow the progression to arthritis, starting with the initiating events of cartilage and meniscus defects. The surgical approaches in current use have a limited capacity for tissue regeneration and yield only short-term relief of symptoms. Tissue engineering approaches are emerging as alternatives to current surgical methods for cartilage and meniscus repair. Several cell-based and tissue-engineered products are currently in clinical trials for cartilage lesions and meniscal tears, opening new avenues for cartilage and meniscus regeneration. This Review provides a summary of surgical techniques, including tissue-engineered products, that are currently in clinical use, as well as a discussion of state-of-the-art tissue engineering strategies and technologies that are being developed for use in articular cartilage and meniscus repair and regeneration. The obstacles to clinical translation of these strategies are also included to inform the development of innovative tissue engineering approaches.

[Research progress of scaffold materials for tissue engineered meniscus]

OBJECTIVE

To summarize and analyze the research progress of scaffold materials used in tissue engineered meniscus.

METHODS

The classification and bionics design of scaffold materials were summarized by consulting domestic and foreign literature related to the research of tissue engineered meniscus in recent years.

RESULTS

Tissue engineered meniscus scaffolds can be roughly classified into synthetic polymers, hydrogels, extracellular matrix components, and tissue derived materials. These different materials have different characteristics, so the use of a single material has its unique disadvantages, and the use of a variety of materials composite scaffolds can learn from each other, which is a hot research area at present. In addition to material selection, material processing methods are also the focus of research. At the same time, according to the morphological structure and mechanical characteristics of the meniscus, the bionic design of tissue engineered meniscus scaffolds has great potential.

CONCLUSION

At present, there are many kinds of scaffold materials for tissue engineered meniscus. However, there is no material that can completely simulate the natural meniscus, and further research of scaffold materials is still needed.

Surgical interventions for symptomatic mild to moderate knee osteoarthritis

BACKGROUND

Osteoarthritis affecting the knee is common and represents a continuum of disease from early cartilage thinning to full-thickness cartilage loss, bony erosion, and deformity. Many studies do not stratify their results based on the severity of the disease at baseline or recruitment.

OBJECTIVES

To assess the benefits and harms of surgical intervention for the management of symptomatic mild to moderate knee osteoarthritis defined as knee pain and radiographic evidence of non-end stage osteoarthritis (Kellgren-Lawrence grade 1, 2, 3 or equivalent on MRI/arthroscopy). Outcomes of interest included pain, function, radiographic progression, quality of life, short-term serious adverse events, re-operation rates and withdrawals due to adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase up to May 2018. We also conducted searches of ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform for ongoing trials. Authors of trials were contacted if some but not all their participants appeared to fit our inclusion criteria.

SELECTION CRITERIA

We included randomised controlled trials that compared surgery to non-surgical interventions (including sham and placebo control groups, exercise or physiotherapy, and analgesic or other medication), injectable therapies, and trials that compared one type of surgical intervention to another surgical intervention in people with symptomatic mild to moderate knee osteoarthritis.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and extracted data using standardised forms. We analysed the quality of evidence using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach.

MAIN RESULTS

A total of five studies involving 566 participants were identified as eligible for this review. Single studies compared arthroscopic partial meniscectomy to physical therapy (320 participants), arthroscopic surgery (debridement ± synovectomy ± chondroplasty) to closed needle joint lavage with saline (32 participants) and high tibial osteotomy surgery to knee joint distraction surgery (62 participants). Two studies (152 participants) compared arthroscopic surgery (washout ± debridement; debridement) to a hyaluronic acid injection. Only one study was at low risk of selection bias, and due to the difficulty of blinding participants to their treatment, all studies were at risk of performance and detection bias.Reporting of results in this summary has been restricted to the primary comparison: surgical intervention versus non-surgical intervention.A single study, included 320 participants with symptoms consistent with meniscal tear. All subjects had the meniscal tear confirmed on knee MRI and radiographic evidence of mild to moderate osteoarthritis (osteophytes, cartilage defect or joint space narrowing). Patients with severe osteoarthritis (KL grade 4) were excluded. The study compared arthroscopic partial meniscectomy and physical therapy to physical therapy alone (a six-week individualised progressive home exercise program). This study was at low risk of selection bias and outcome reporting biases, but was susceptible to performance and detection biases. A high rate of cross-over (30.2%) occurred from the physical therapy group to the arthroscopic group.Low-quality evidence suggests there may be little difference in pain and function at 12 months follow-up in people who have arthroscopic partial meniscectomy and those who have physical therapy. Evidence was downgraded to low quality due to risk of bias and imprecision.Mean pain was 19.3 points on a 0 to 100 point KOOS pain scale with physical therapy at 12 months follow-up and was 0.2 points better with surgery (95% confidence interval (CI) 4.05 better to 3.65 points worse with surgery, an absolute improvement of 0.2% (95% CI 4% better to 4% worse) and relative improvement 0.4% (95% CI 9% better to 8% worse) (low quality evidence). Mean function was 14.5 on a 0 to 100 point KOOS function scale with physical therapy at 12 months follow-up and 0.8 points better with surgery (95% CI 4.3 better to 2.7 worse); 0.8% absolute improvement (95% CI 4% better to 3% worse) and 2.1% relative improvement (95% CI 11% better to 7% worse) (low quality evidence).Radiographic structural osteoarthritis progression and quality of life outcomes were not reported.Due to very low quality evidence, we are uncertain if surgery is associated with an increased risk of serious adverse events, incidence of total knee replacement or withdrawal rates. Evidence was downgraded twice due to very low event rates, and once for risk of bias.At 12 months, the surgery group had a total of three serious adverse events including fatal pulmonary embolism, myocardial infarction and hypoxaemia. The physical therapy alone group had two serious adverse events including sudden death and stroke (Peto OR 1.58, 95% CI 0.27 to 9.21); 1% more events with surgery (95% CI 2% less to 3% more) and 58% relative change (95% CI 73% less to 821% more). One participant in each group withdrew due to adverse events.Two of 164 participants (1.2%) in the physical therapy group and three of 156 in the surgery group underwent conversion to total knee replacement within 12 months (Peto OR 1.76, 95% CI 0.43 to 7.13); 1% more events with surgery (95% CI 2% less to 5% more); 76% relative change (95% CI 57% less to 613% more).

AUTHORS' CONCLUSIONS

The review found no placebo-or sham-controlled trials of surgery in participants with symptomatic mild to moderate knee osteoarthritis. There was low quality evidence that there may be no evidence of a difference between arthroscopic partial meniscectomy surgery and a home exercise program for the treatment of this condition. Similarly, low-quality evidence from a few small trials indicates there may not be any benefit of arthroscopic surgery over other non-surgical treatments including saline irrigation and hyaluronic acid injection, or one type of surgery over another. We are uncertain of the risk of adverse events or of progressing to total knee replacement due to very small event rates. Thus, there is uncertainty around the current evidence to support or oppose the use of surgery in mild to moderate knee osteoarthritis. As no benefit has been demonstrated from the low quality trials included in this review, it is possible that future higher quality trials for these surgical interventions may not contradict these results.

Characterization of a novel polyvinyl alcohol/chitosan porous hydrogel combined with bone marrow mesenchymal stem cells and its application in articular cartilage repair

BACKGROUND

Different substances are combined to compensate for each other's drawbacks and create an appropriate biomaterial. A novel Polyvinyl alcohol (PVA)/chitosan (CS) porous hydrogel was designed and applied to the treatment of osteochondral defects.

METHODS

Hydrogels of various PVA/CS ratios were tested for physiochemical and mechanical properties in addition to cytotoxicity and biocompatibility. The hydrogels with the best PVA/CS ratio were used in the animal study. Osteochondral defects were created at the articular cartilage of 18 rabbits. They were assigned to different groups randomly (n = 6 per group): the osteochondral defect only group (control group), the osteochondral defect treated with hydrogel group (HG group), and the osteochondral defect treated with hydrogel loaded with bone marrow mesenchymal stem cells (BMSCs) group (HG-BMSCs group). The cartilage was collected for macro-observation and histological evaluation at 12 weeks after surgery.

RESULTS

The Hydrogel with PVA/CS ratio of 6:4 exhibited the best mechanical properties; it also showed stable physical and chemical properties with porosity and over 90% water content. Furthermore, it demonstrated no cytotoxicity and was able to promote cell proliferation. The HG-BMSCs group achieved the best cartilage healing.

CONCLUSIONS

The novel PVA/CS porous composite hydrogel could be a good candidate for a tissue engineering material in cartilage repair.

A Composite Chitosan-Reinforced Scaffold Fails to Provide Osteochondral Regeneration

Several biomaterials have recently been developed to address the challenge of osteochondral regeneration. Among these, chitosan holds promises both for cartilage and bone healing. The aim of this in vivo study was to evaluate the regeneration potential of a novel hybrid magnesium-doped hydroxyapatite (MgHA), collagen, chitosan-based scaffold, which was tested in a sheep model to ascertain its osteochondral regenerative potential, and in a rabbit model to further evaluate its ability to regenerate bone tissue. Macroscopic, microtomography, histology, histomorphometry, and immunohistochemical analysis were performed. In the sheep model, all analyses did not show significant differences compared to untreated defects (p > 0.05), with no evidence of cartilage and subchondral bone regeneration. In the rabbit model, this bone scaffold provided less ability to enhance tissue healing compared with a commercial bone scaffold. Moreover, persistence of scaffold material and absence of integration with connective tissue around the scaffolds were observed. These results raised some concerns about the osteochondral use of this chitosan composite scaffold, especially for the bone layer. Further studies are needed to explore the best formulation of chitosan-reinforced composites for osteochondral treatment.

Biomaterials to Mimic and Heal Connective Tissues

Connective tissue is one of the four major types of animal tissue and plays essential roles throughout the human body. Genetic factors, aging, and trauma all contribute to connective tissue dysfunction and motivate the need for strategies to promote healing and regeneration. The goal here is to link a fundamental understanding of connective tissues and their multiscale properties to better inform the design and translation of novel biomaterials to promote their regeneration. Major clinical problems in adipose tissue, cartilage, dermis, and tendon are discussed that inspire the need to replace native connective tissue with biomaterials. Then, multiscale structure-function relationships in native soft connective tissues that may be used to guide material design are detailed. Several biomaterials strategies to improve healing of these tissues that incorporate biologics and are biologic-free are reviewed. Finally, important guidance documents and standards (ASTM, FDA, and EMA) that are important to consider for translating new biomaterials into clinical practice are highligted.

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.

Microfractures and hydrogel scaffolds in the treatment of osteochondral knee defects: A clinical and histological evaluation

BACKGROUND

Osteochondral knee defects (OCD) are often symptomatic, causing pain and functional impairment even in young and active patients. Regenerative surgical options, aiming to stimulate natural cartilage healing, have been recently used as a first line treatment. In this study, a new hydrogel is investigated in its capacity to regenerate the ultra-structural quality of hyaline cartilage when combined with a classical microfracture technique.

MATERIAL AND METHODS

Forty-six patients, affected by grade III and IV knee chondropathies, were consecutively treated between 2013 and 2015 with microfractures followed by application of a modern hydrogel in the lesion site. All patients underwent clinical evaluation (WOMAC) pre-operatively, at 6,12 and at 24 months postoperatively: the results were compared with a subsequent, consecutive, matched, control group of 23 patients treated with microfractures alone. In a parallel and separate in-vitro histological study, adipose derived mesenchymal stem cells (ADMSCs) were encapsulated in the hydrogel scaffold, induced to differentiation into chondrocytes, and observed for a 3 weeks period.

RESULTS

The initial WOMAC score of 58.6 ± 11.0 in the study group was reduced by 88% at 6 months (7.1 ± 9.2) and 95% at 24 months (2.9 ± 5.9). The "in-vitro" study revealed a histological characterization typical of hyaline cartilage in study group. Separate biopsies performed at 12 months post-op in the study group also revealed type 2 collagen and hyaline-like cartilage in the regenerated tissue.

CONCLUSION

Our study demonstrated high patient satisfaction rates after microfractures combined with a modern hydrogel scaffold; histologic evaluation supported the hypothesis of creating an enhanced chondrogenic environment. Microfracture "augmentation" using modern acellular biomaterials, like hydrogels, might improve the clinical outcomes of this classical bone marrow stimulating procedure.

Arthroscopic and open treatment of cartilage lesions with BST-CARGEL scaffold and microfracture: A cohort study of consecutive patients

BACKGROUND

CARGEL (Smith & Nephew Inc.), a chitosan-based polymer scaffolding biomaterial, has been used since 2012 for treating articular cartilage lesions. Limited data are available on patient outcomes following CARGEL treatment. This study aimed to describe short-term clinical and radiographic outcomes in a cohort of patients treated with CARGEL and microfracture surgery for articular cartilage defects in the knee.

METHODS

A retrospective cohort study was conducted of consecutive patients with articular cartilage defects who had undergone microfracture surgery with CARGEL, or in patellar lesions microfracture and CARGEL plus Chondro-Gide (at SportsClinic Zurich). Study outcomes included reoperations, infections, allergic reactions, pain, swelling, range of motion, and tissue quality and quantity. Ethics approval was obtained from the local ethics committee on 05/09/2017 (Basec. Nr: 2017-01441).

RESULTS

A total of 91 participants, with 93 treated lesions, consenting to chart review were included. No participants required reoperation due to complications on the index lesion. Fifteen participants had second-look surgery on the index knee for other reasons, allowing for visual confirmation of cartilage repair. No study participants experienced a post-surgical infection or suffered an allergic reaction. No significant changes in range of motion or T2 values were observed from pre-treatment to post-treatment follow-up. However, significant decreases were found in pain (P < 0.001) and swelling (P < 0.001), along with significant increases in MOCART II scores (P < 0.001). Similar results were found in a subgroup of patients with patellar lesions.

CONCLUSIONS

Patients treated with CARGEL experienced few postoperative complications and reported promising reductions in pain and swelling after treatment.

LEVEL OF EVIDENCE

IV.

Arthroscopic Repair of Acetabular Cartilage Lesions by Chitosan-Based Scaffold: Clinical Evaluation at Minimum 2 Years Follow-up

PURPOSE

To evaluate the functional outcome of using chitosan-based material in our patients after 2 years of follow-up.

METHODS

Nonarthritic nondysplastic femoroacetabular impingement patients with an acetabular chondral lesion, 18 to 55 years of age, were included for arthroscopic repair between May 2013 and July 2015. Full-thickness chondral defects ≥2 cm² were filled with chitosan-based implant after microfractures. Follow-up consisted of alpha angle assessment and clinical outcome in the form of the Non Arthritic Hip Score (NAHS), International Hip Outcome Tool 33 (iHOT33), Hip Outcome Score of Activities of Daily Living (HOS-ADL), and Hip Outcome Score of Sports Specific Scale (HOS-SSS).

RESULTS

Twenty-three patients were included. The mean follow-up was 38.4 ± 7.0 months (range, 24-50 months). The mean defect size was 3.5 ± 1.0 cm², principally involving zone 2 and to a lesser extent in zones 1 and 3. Using femoroplasty, the alpha angle was corrected from a mean 70.5 ± 6.3° to 44.3 ± 4.9° (P = .00001). Significant improvement occurred comparing the preoperative to the first-year postoperative patient-reported outcomes: P = .00001 for the NAHS, P = .00004 for the iHOT33, P = .00005 for the HOS-ADL, and P = .0002 for the HOS-SSS. No statistically significant change has been observed in the patient-reported outcomes obtained at the endpoint when compared with the first-year values (P = .13 for the NAHS, P = .21 for the HOS-ADL, and P = .29 for the HOS-SSS), except for the iHOT33, which showed further significant improvement (P = .02). Up to 91% of the patients met or exceeded the minimal clinically important difference. One patient needed total hip arthroplasty. Perineal hypoesthesia occurred in 3 patients, who recovered within 2 to 6 weeks, and 1 patient needed a prolonged physiotherapy program for postoperative muscular stiffness.

CONCLUSIONS

The arthroscopic combined treatment of microfractures and chitosan-based scaffold has maintained satisfactory clinical outcomes in 91% of the patients with s large (≥2 cm²) full-thickness acetabular chondral defect associated with femoroacetabular impingement at a mean follow-up of 38.4 months. The study could not definitely draw any conclusion regarding the safety of chitosan-based material for use in the hip joint.

LEVEL OF EVIDENCE

Level IV, case series.

Editorial Commentary: Acetabular Cartilage Repair: A Critically Important Frontier in Hip Preservation

Articular cartilage damage to the acetabulum is frequently associated with femoroacetabular impingement, and there are considerable long-term implications for such injury with regard to maintenance of a healthy hip joint and quality of life. Developing treatments capable of restoring articular cartilage to acetabular cartilage defects is of great importance if hip preservation treatments are to be successful. Ideally, such methods should be performed in a minimally invasive manner and be capable of restoring durable repair tissue that reconstitutes a healthy osteochondral unit and that continues to function effectively over the long term.

Challenges in Fabrication of Tissue-Engineered Cartilage with Correct Cellular Colonization and Extracellular Matrix Assembly

A correct articular cartilage ultrastructure regarding its structural components and cellularity is important for appropriate performance of tissue-engineered articular cartilage. Various scaffold-based, as well as scaffold-free, culture models have been under development to manufacture functional cartilage tissue. Even decellularized tissues have been considered as a potential choice for cellular seeding and tissue fabrication. Pore size, interconnectivity, and functionalization of the scaffold architecture can be varied. Increased mechanical function requires a dense scaffold, which also easily restricts cellular access within the scaffold at seeding. High pore size enhances nutrient transport, while small pore size improves cellular interactions and scaffold resorption. In scaffold-free cultures, the cells assemble the tissue completely by themselves; in optimized cultures, they should be able to fabricate native-like tissue. Decellularized cartilage has a native ultrastructure, although it is a challenge to obtain proper cellular colonization during cell seeding. Bioprinting can, in principle, provide the tissue with correct cellularity and extracellular matrix content, although it is still an open question as to how the correct molecular interaction and structure of extracellular matrix could be achieved. These are challenges facing the ongoing efforts to manufacture optimal articular cartilage.

Bone Marrow Stimulation Technique Augmented by an Ultrapurified Alginate Gel Enhances Cartilage Repair in a Canine Model

BACKGROUND

The optimal treatment for a medium- or large-sized cartilage lesion is still controversial. Since an ultrapurified alginate (UPAL) gel enhances cartilage repair in animal models, this material is expected to improve the efficacy of the current treatment strategies for cartilage lesions.

HYPOTHESIS

The bone marrow stimulation technique (BMST) augmented by UPAL gel can induce hyaline-like cartilage repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

Two cylindrical osteochondral defects were created in the patellar groove of 27 beagle dogs. A total of 108 defects were divided into 3 groups: defects without intervention (control group), defects with the BMST (microfracture group), and defects with the BMST augmented by implantation of UPAL gel (combined group). At 27 weeks postoperatively, macroscopic and histological evaluations, micro-computed tomography assessment, and mechanical testing were performed for each reparative tissue.

RESULTS

The defects in the combined group were almost fully covered with translucent reparative tissues, which consisted of hyaline-like cartilage with well-organized collagen structures. The macroscopic score was significantly better in the combined group than in the control group ( P < .05). The histological scores in the combined group were significantly better than those in the control group ( P < .01) and microfracture group ( P < .05). Although the repaired subchondral bone volumes were not influenced by UPAL gel augmentation, the mechanical properties of the combined group were significantly better than those of the microfracture group ( P < .05).

CONCLUSION

The BMST augmented by UPAL gel elicited hyaline-like cartilage repair that had characteristics of rich glycosaminoglycan and matrix immunostained by type II collagen antibody in a canine osteochondral defect model. The present results suggest that the current technique has the potential to be one of the autologous matrix-induced chondrogenesis techniques of the future and to expand the operative indications for the BMST without loss of its technical simplicity.

CLINICAL RELEVANCE

The data support the clinical reality of 1-step minimally invasive cartilage-reparative medicine with UPAL gel without harvesting donor cells.

Matrix-Applied Characterized Autologous Cultured Chondrocytes Versus Microfracture: Five-Year Follow-up of a Prospective Randomized Trial

BACKGROUND

Matrix-based cell therapy improves surgical handling, increases patient comfort, and allows for expanded indications with better reliability within the knee joint. Five-year efficacy and safety of autologous cultured chondrocytes on porcine collagen membrane (MACI) versus microfracture for treating cartilage defects have not yet been reported from any randomized controlled clinical trial.

PURPOSE

To examine the clinical efficacy and safety results at 5 years after treatment with MACI and compare these with the efficacy and safety of microfracture treatment for symptomatic cartilage defects of the knee.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

This article describes the 5-year follow-up of the SUMMIT (Superiority of MACI Implant Versus Microfracture Treatment) clinical trial conducted at 14 study sites in Europe. All 144 patients who participated in SUMMIT were eligible to enroll; analyses of the 5-year data were performed with data from patients who signed informed consent and continued in the Extension study.

RESULTS

Of the 144 patients randomized in the SUMMIT trial, 128 signed informed consent and continued observation in the Extension study: 65 MACI (90.3%) and 63 microfracture (87.5%). The improvements in Knee injury and Osteoarthritis Outcome Score (KOOS) Pain and Function domains previously described were maintained over the 5-year follow-up. Five years after treatment, the improvement in MACI over microfracture in the co-primary endpoint of KOOS pain and function was maintained and was clinically and statistically significant ( P = .022). Improvements in activities of daily living remained statistically significantly better ( P = .007) in MACI patients, with quality of life and other symptoms remaining numerically higher in MACI patients but losing statistical significance relative to the results of the SUMMIT 2-year analysis. Magnetic resonance imaging (MRI) evaluation of structural repair was performed in 120 patients at year 5. As in the 2-year SUMMIT (MACI00206) results, the MRI evaluation showed improvement in defect filling for both treatments; however, no statistically significant differences were noted between treatment groups.

CONCLUSION

Symptomatic cartilage knee defects 3 cm² or larger treated with MACI were clinically and statistically significantly improved at 5 years compared with microfracture treatment. No remarkable adverse events or safety issues were noted in this heterogeneous patient population.

Blood derivatives awaken in regenerative medicine strategies to modulate wound healing

Blood components play key roles in the modulation of the wound healing process and, together with the provisional fibrin matrix ability to selectively bind bioactive molecules and control its spatial-temporal presentation, define the complex microenvironment that characterize this biological process. As a biomimetic approach, the use of blood derivatives in regenerative strategies has awakened as a source of multiple therapeutic biomolecules. Nevertheless, and despite their clinical relevance, blood derivatives have been showing inconsistent therapeutic results due to several factors, including proper control over their delivery mechanisms. Herein, we highlight recent trends on the use biomaterials to protect, sequester and deliver these pools of biomolecules in tissue engineering and regenerative medicine approaches. Particular emphasis is given to strategies that enable to control their spatiotemporal delivery and improve the selectivity of presentation profiles of the biomolecules derived from blood derivatives rich in platelets. Finally, we discussed possible directions for biomaterials design to potentiate the aimed regenerative effects of blood derivatives and achieve efficient therapies.

Can Biologic Augmentation Improve Clinical Outcomes Following Microfracture for Symptomatic Cartilage Defects of the Knee? A Systematic Review

Objective To perform a systematic review of clinical outcomes following microfracture augmented with biological adjuvants (MFX+) compared with microfracture (MFX) alone. Design The MEDLINE, Scopus, and Cochrane databases were searched for clinical studies on MFX+ for chondral defects of the knee. Study characteristics and clinical outcome score data were collected. Subjective synthesis was performed using data from randomized controlled studies to determine effect size of MFX+ procedures performed with either injectable or scaffold-based augmentation compared with MFX alone. Results A total of 18 articles reporting on 625 patients (491 MFX+, 134 MFX) were identified. Six studies were level II evidence and 1 study was level I evidence. Mean patient age range was 26 to 51 years, and mean follow-up ranged from 2 to 5 years. All studies demonstrated significant improvement in reported clinical outcome scores at follow-up after MFX+ therapy, and 87% of patients reported satisfaction with treatment. The most commonly reported treatment complication was postoperative stiffness (3.9% of patients). Subjective synthesis on randomized controlled trials demonstrated that 2/2 injectable MFX+ interventions had significantly greater improvements in International Knee Documentation Committee Subjective Knee Form (IKDC; P = 0.004) and Knee injury and Osteoarthritis Outcome Score (KOOS; P = 0.012) scores compared with MFX alone, while 2/2 trials on scaffolding MFX+ adjuvants showed comparable postoperative improvements. Conclusions MFX+ biological adjuvants are safe supplements to marrow stimulation for treating cartilage defects in the adult knee. Early literature is heterogenous and extremely limited in quality. Individual trials report both equivalent and superior clinical outcomes compared with MFX alone, making definitive conclusions on the efficacy of MFX+ difficult without higher quality evidence.

Bioactive Sr(II)/Chitosan/Poly(ε-caprolactone) Scaffolds for Craniofacial Tissue Regeneration. In Vitro and In Vivo Behavior

In craniofacial tissue regeneration, the current gold standard treatment is autologous bone grafting, however, it presents some disadvantages. Although new alternatives have emerged there is still an urgent demand of biodegradable scaffolds to act as extracellular matrix in the regeneration process. A potentially useful element in bone regeneration is strontium. It is known to promote stimulation of osteoblasts while inhibiting osteoclasts resorption, leading to neoformed bone. The present paper reports the preparation and characterization of strontium (Sr) containing hybrid scaffolds formed by a matrix of ionically cross-linked chitosan and microparticles of poly(ε-caprolactone) (PCL). These scaffolds of relatively facile fabrication were seeded with osteoblast-like cells (MG-63) and human bone marrow mesenchymal stem cells (hBMSCs) for application in craniofacial tissue regeneration. Membrane scaffolds were prepared using chitosan:PCL ratios of 1:2 and 1:1 and 5 wt % Sr salts. Characterization was performed addressing physico-chemical properties, swelling behavior, in vitro biological performance and in vivo biocompatibility. Overall, the composition, microstructure and swelling degree (≈245%) of scaffolds combine with the adequate dimensional stability, lack of toxicity, osteogenic activity in MG-63 cells and hBMSCs, along with the in vivo biocompatibility in rats allow considering this system as a promising biomaterial for the treatment of craniofacial tissue regeneration.

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.

Current and novel injectable hydrogels to treat focal chondral lesions: Properties and applicability

Focal chondral lesions and early osteoarthritis (OA) are responsible for progressive joint pain and disability in millions of people worldwide, yet there is currently no surgical joint preservation treatment available to fully restore the long term functionality of cartilage. Limitations of current treatments for cartilage defects have prompted the field of cartilage tissue engineering, which seeks to integrate engineering and biological principles to promote the growth of new cartilage to replace damaged tissue. Toward improving cartilage repair, hydrogel design has advanced in recent years to improve their utility. Injectable hydrogels have emerged as a promising scaffold due to their wide range of properties, the ability to encapsulate cells within the material, and their ability to provide cues for cell differentiation. Some of these advances include the development of improved control over in situ gelation (e.g., light), new techniques to process hydrogels (e.g., multi-layers), and better incorporation of biological signals (e.g., immobilization, controlled release, and tethering). This review summarises the innovative approaches to engineer injectable hydrogels toward cartilage repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:64-75, 2018.

Emerging Concepts in Treating Cartilage, Osteochondral Defects, and Osteoarthritis of the Knee and Ankle

The management and treatment of cartilage lesions, osteochondral defects, and osteoarthritis remain a challenge in orthopedics. Moreover, these entities have different behaviors in different joints, such as the knee and the ankle, which have inherent differences in function, biology, and biomechanics. There has been a huge development on the conservative treatment (new technologies including orthobiologics) as well as on the surgical approach. Some surgical development upraises from technical improvements including advanced arthroscopic techniques but also from increased knowledge arriving from basic science research and tissue engineering and regenerative medicine approaches. This work addresses the state of the art concerning basic science comparing the knee and ankle as well as current options for treatment. Furthermore, the most promising research developments promising new options for the future are discussed.

Commercial Products for Osteochondral Tissue Repair and Regeneration

The osteochondral tissue represents a complex structure composed of four interconnected structures, namely hyaline cartilage, a thin layer of calcified cartilage, subchondral bone, and cancellous bone. Due to the several difficulties associated with its repair and regeneration, researchers have developed several studies aiming to restore the native tissue, some of which had led to tissue-engineered commercial products. In this sense, this chapter discusses the good manufacturing practices, regulatory medical conditions and challenges on clinical translations that should be fulfilled regarding the safety and efficacy of the new commercialized products. Furthermore, we review the current osteochondral products that are currently being marketed and applied in the clinical setting, emphasizing the advantages and difficulties of each one.

Results of arthroscopic treatment of chondral delamination in femoroacetabular impingement with bone marrow stimulation and BST-CarGel®

Objectives: The purpose of this study is to show the preliminary results of using chitosan-based scaffold (BST-CarGel^®) with microfracture for treatment of acetabular chondral delamination associated with femoroacetabular impingement.

Methods: A prospective study was performed on 13 hips. Patients were selected in the age group between 18 and 50 years. Patients with delamination of acetabular cartilage associated with femoroacetabular impingement received arthroscopic debridement and microfracture technique. Then cases with defect > 2 cm² were considered for the application of BST-CarGel^® and included in the study. Also, reattachment of the torn labrum and resection of the cam deformity were performed according to the case. For evaluation of the functional outcome, the patients had completed the hip outcome score (HOS) pre- and post-operatively. For evaluation of the regeneration of the cartilage, delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) was used and the percentage of defect filling and type of cartilage studied.

Results: Patients had a mean age of 41 years, with moderate to high level of activity (mean Tegner scale 7). The mean size of the chondral defect after debridement was 3.7 cm². The mean HOS for daily live activities has been improved from 64.4 to 87.4 and for sports subscale from 35.2 to 75.2, which is statistically highly significant. All patients had > 90% of filling of chondral defect.

Conclusion: The use of BST-CarGel^® with microfracture for treatment of acetabular chondral delamination associated with femoroacetabular impingement can improve the functional outcome at two years, with a complete restoration of the cartilage defect in magnetic resonance images (MRI) with specific cartilage sequences.

Recent strategies in cartilage repair: A systemic review of the scaffold development and tissue engineering

Osteoarthritis results in irreparable loss of articular cartilage. Due to its avascular nature and low mitotic activity, cartilage has little intrinsic capacity for repair. Cartilage loss leads to pain, physical disability, movement restriction, and morbidity. Various treatment strategies have been proposed for cartilage regeneration, but the optimum treatment is yet to be defined. Tissue engineering with engineered constructs aimed towards developing a suitable substrate may help in cartilage regeneration by providing the mechanical, biological and chemical support to the cells. The use of scaffold as a substrate to support the progenitor cells or autologous chondrocytes has given promising results. Leakage of cells, poor cell survival, poor cell differentiation, inadequate integration into the host tissue, incorrect distribution of cells, and dedifferentiation of the normal cartilage are the common problems in tissue engineering. Current research is focused on improving mechanical and biochemical properties of scaffold to make it more efficient. The aim of this review is to provide a critical discussion on existing challenges, scaffold type and properties, and an update on ongoing recent developments in the architecture and composition of scaffold to enhance the proliferation and viability of mesenchymal stem cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2343-2354, 2017.