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

Does progress in microfracture techniques necessarily translate into clinical effectiveness?

BACKGROUND

Multitudinous advancements have been made to the traditional microfracture (MFx) technique, which have involved delivery of various acellular 2nd generation MFx and cellular MFx-III components to the area of cartilage defect. The relative benefits and pitfalls of these diverse modifications of MFx technique are still not widely understood.

AIM

To comparatively analyze the functional, radiological, and histological outcomes, and complications of various generations of MFx available for the treatment of cartilage defects.

METHODS

A systematic review was performed using PubMed, EMBASE, Web of Science, Cochrane, and Scopus. Patients of any age and sex with cartilage defects undergoing any form of MFx were considered for analysis. We included only randomized controlled trials (RCTs) reporting functional, radiological, histological outcomes or complications of various generations of MFx for the management of cartilage defects. Network meta-analysis (NMA) was conducted in Stata and Cochrane's Confidence in NMA approach was utilized for appraisal of evidence.

RESULTS

Forty-four RCTs were included in the analysis with patients of mean age of 39.40 (± 9.46) years. Upon comparing the results of the other generations with MFX-I as a constant comparator, we noted a trend towards better pain control and functional outcome (KOOS, IKDC, and Cincinnati scores) at the end of 1-, 2-, and 5-year time points with MFx-III, although the differences were not statistically significant (P > 0.05). We also noted statistically significant Magnetic resonance observation of cartilage repair tissue score in the higher generations of microfracture (weighted mean difference: 17.44, 95% confidence interval: 0.72, 34.16, P = 0.025; without significant heterogeneity) at 1 year. However, the difference was not maintained at 2 years. There was a trend towards better defect filling on MRI with the second and third generation MFx, although the difference was not statistically significant (P > 0.05).

CONCLUSION

The higher generations of traditional MFx technique utilizing acellular and cellular components to augment its potential in the management of cartilage defects has shown only marginal improvement in the clinical and radiological outcomes.

[On the use of type I tropocollagen for local injection therapy of spine, upper and lower extremity disorders]

A meeting of Interdisciplinary Expert Panel with leading specialists in the field of orthopedics/traumatology, surgery, rheumatology, and neurology was held in Moscow on February 10, 2023. The purpose of the meeting was to discuss the current status of local injection therapy (LIT) in Russia and the rationale behind the use of collagen-based products for various musculoskeletal disorders. The experts considered the following issues: (1) General contraindications to the use of medical products based on tropocollagen as well as an algorithm for actions in case of adverse events; (2) Guidelines regarding LIT in general and LIT using tropocollagen in particular, including in combination with other LIT products; (3) Particular indications and approaches to the treatment of patients with abnormal changes in appendicular joints and spine with damage to both intra-articular structures and periarticular soft tissue.

Knee Cartilage Lesion Management-Current Trends in Clinical Practice

Many patients, particularly those aged above 40, experience knee joint pain, which hampers both sports activities and daily living. Treating isolated chondral and osteochondral defects in the knee poses a significant clinical challenge, particularly in younger patients who are not typically recommended partial or total knee arthroplasty as alternatives. Several surgical approaches have been developed to address focal cartilage defects. The treatment strategies are characterized as palliation (e.g., chondroplasty and debridement), repair (e.g., drilling and microfracture), or restoration (e.g., autologous chondrocyte implantation, osteochondral autograft, and osteochondral allograft). This review offers an overview of the commonly employed clinical methods for treating articular cartilage defects, with a specific focus on the clinical trials conducted in the last decade. Our study reveals that, currently, no single technology fully meets the essential requirements for effective cartilage healing while remaining easily applicable during surgical procedures. Nevertheless, numerous methods are available, and the choice of treatment should consider factors such as the location and size of the cartilage lesion, patient preferences, and whether it is chondral or osteochondral in nature. Promising directions for the future include tissue engineering, stem cell therapies, and the development of pre-formed scaffolds from hyaline cartilage, offering hope for improved outcomes.

Autologous Collagen-Induced Chondrogenesis: From Bench to Clinical Development

Microfracture is a common technique that uses bone marrow components to stimulate cartilage regeneration. However, the clinical results of microfracture range from poor to good. To enhance cartilage healing, several reinforcing techniques have been developed, including porcine-derived collagen scaffold, hyaluronic acid, and chitosan. Autologous collagen-induced chondrogenesis (ACIC) is a single-step surgical technique for cartilage regeneration that combines gel-type atelocollagen scaffolding with microfracture. Even though ACIC is a relatively new technique, literature show excellent clinical results. In addition, all procedures of ACIC are performed arthroscopically, which is increasing in preference among surgeons and patients. The ACIC technique also is called the Shetty–Kim technique because it was developed from the works of A.A. Shetty and S.J. Kim. This is an up-to-date review of the history of ACIC.

An Update on the Clinical Efficacy and Safety of Collagen Injectables for Aesthetic and Regenerative Medicine Applications

Soft tissues diseases significantly affect patients quality of life and usually require targeted, costly and sometimes constant interventions. With the average lifetime increase, a proportional increase of age-related soft tissues diseases has been witnessed. Due to this, the last two decades have seen a tremendous demand for minimally invasive one-step resolutive procedures. Intensive scientific and industrial research has led to the recognition of injectable formulations as a new advantageous approach in the management of complex diseases that are challenging to treat with conventional strategies. Among them, collagen-based products are revealed to be one of the most promising among bioactive biomaterials-based formulations. Collagen is the most abundant structural protein of vertebrate connective tissues and, because of its structural and non-structural role, is one of the most widely used multifunctional biomaterials in the health-related sectors, including medical care and cosmetics. Indeed, collagen-based formulations are historically considered as the "gold standard" and from 1981 have been paving the way for the development of a new generation of fillers. A huge number of collagen-based injectable products have been approved worldwide for clinical use and have routinely been introduced in many clinical settings for both aesthetic and regenerative surgery. In this context, this review article aims to be an update on the clinical outcomes of approved collagen-based injectables for both aesthetic and regenerative medicine of the last 20 years with an in-depth focus on their safety and effectiveness for the treatment of diseases of the integumental, gastrointestinal, musculoskeletal, and urogenital apparatus.

Zonally Stratified Decalcified Bone Scaffold with Different Stiffness Modified by Fibrinogen for Osteochondral Regeneration of Knee Joint Defect

Articular cartilage is generally known to be a complex tissue with multiple layers. Each layer has different composition, structure, and mechanical properties, making regeneration after knee joint defects a troubling clinical problem. A novel integrated stratified decalcified bone matrix (SDBM) scaffold with different stiffness to mimic the mechanical properties of articular cartilage is presented herein. This SDBM scaffold was modified using fibrinogen (Fg) (Fg + SDBM) to enhance its vascularization ability and improve its repair efficiency for osteochondral defects of knee joints. A Fg + SDBM scaffold with different elastic modulus in each layer (high-stiffness DBM (HDBM) layer, 174.208 ± 44.330 MPa (Fg + HDBM); medium-stiffness DBM (MDBM) layer, 21.214 ± 6.922 MPa (Fg + MDBM); and low-stiffness DBM (LDBM) layer, 0.678 ± 0.269 MPa (Fg + LDBM)) was constructed by controlling the stratified decalcification time with layered embedding paraffin (0, 3, and 5 days). The low- and medium-stiffness layers of the Fg + SDBM scaffold remarkably promoted the cartilage differentiation of bone marrow mesenchymal stem cells in vitro. Subcutaneous transplantation and rabbit knee joint osteochondral defect repair experiments revealed that the low- and medium-stiffness layers of the Fg + SDBM scaffold exhibited wonderful cartilage capacity, whereas the high-stiffness layer of Fg + SDBM scaffold exhibited good osteogenesis ability. Furthermore, this scaffold could promote blood vessel formation in subchondral bone area. This study presents a feasible strategy for osteochondral regeneration of defective knee joints, which is of great clinical value for tissue repair.

Injectable Scaffold with Microfracture using the Autologous Matrix-Induced Chondrogenesis (AMIC) Technique: A Prospective Cohort Study

Introduction

Autologous matrix-induced chondrogenesis (AMIC) is a one-step surgical cartilage repair procedure involving the insertion of a scaffold into the chondral defect after microfracture. BST-CarGel [Smith and Nephew, Watford, England] is an injectable chitosan-based scaffold which can more easily fill defects with irregular shapes and be used to treat vertical or roof chondral lesions. The study aims to evaluate the clinical outcomes of knee cartilage repair with microfracture surgery and BST-CarGel using the AMIC technique for a minimum of two years.

Materials and methods

A prospective study of patients undergoing cartilage repair with microfracture surgery and BST-CarGel at our institution from 2016 to 2019 was performed. Clinical outcomes were determined using the Lysholm Knee Scoring System and Knee Injury and Osteoarthritis Outcome Score (KOOS). These questionnaires were administered before the surgery and at a minimum of two years after surgery.

Results

A total of 21 patients were identified and recruited into the study. 31 cartilage defects were seen and treated in 21 knees. These included horizontal lesions (e.g., trochlear, lateral tibial plateau), vertical lesions (e.g., medial femoral condyle, lateral femoral condyle) and inverted lesions (e.g., patella). No complications or reoperations were seen in our study population. For the average duration of follow-up of 42.5±8.55 months, there was an average improvement in Lysholm score of 25.8±18.6 and an average improvement in KOOS score of 22.5±15.0.

Conclusion

BST-CarGel with microfracture surgery using the AMIC technique is a safe and effective treatment for cartilage defects in the short to medium term.

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.

Recent Biomimetic Approaches for Articular Cartilage Tissue Engineering and Their Clinical Applications: Narrative Review of the Literature

Since articular cartilage is lacking blood vessels and nerves, its capacity to heal is extremely limited. This means that ruptured cartilage affects the joint as a whole. A health issue known as osteoarthritis can develop as a result of injury and deterioration. Osteoarthritis development can be speeded up by the widespread deterioration of articular cartilage, which ranks third on the list of musculoskeletal disorders requiring rehabilitation, behind only low back pain and broken bones. The current treatments for cartilage repair are ineffective and rarely restore full function or tissue normalcy. A promising new technology in tissue engineering may help create functional cartilage tissue substitutes. Ensuring that the cell source is loaded with bioactive molecules that promote cellular differentiation and/or maturation is the general approach. This review summarizes recent advances in cartilage tissue engineering, and recent clinical trials have been conducted to provide a comprehensive overview of the most recent research developments and clinical applications in the framework of degenerated articular cartilage and osteoarthritis.

Marrow Stimulation Has Relatively Inferior Patient-Reported Outcomes in Cartilage Restoration Surgery of the Knee: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Multiple cartilage repair techniques are available for chondral defects in the knee. Optimal treatment is controversial.

PURPOSE

To evaluate change from baseline in the 5 Knee injury and Osteoarthritis Outcome Score (KOOS) subscales among different cartilage repair techniques of the knee.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 1A.

METHODS

Medline and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched for randomized controlled trials with minimum 1 year follow-up reporting change from baseline KOOS (delta KOOS) subscale values. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed. A meta-analysis was performed on the following surgery types: microfracture (Mfx); augmented microfracture techniques (Mfx+Augment); and culture-based therapies, including autologous chondrocyte implantation (ACI) and matrix-assisted autologous chondrocyte implantation (MACI). A random-effects metaregression model was used.

RESULTS

A total of 14 randomized trials with a total of 775 patients were included. The KOOS Sport and Recreation (Sport) and KOOS Quality of Life (QOL) were the 2 most responsive subscales after operative intervention. Outcomes from Mfx and Mfx+Augment were not different in any of the 5 KOOS subscales (minimum P > .3). The mean delta KOOS Sport after ACI/MACI was 9.9 points greater than after Mfx (P = .021) and 11.7 points greater than after Mfx+Augment (P = .027). Longer follow-up time correlated with greater delta KOOS Sport (P = .028). Larger body mass index led to greater delta KOOS QOL (P = .045). Larger cartilage defect size correlated with greater delta KOOS Pain and KOOS Activities of Daily Living scores (P = .023 and P = .002, respectively).

CONCLUSION

The KOOS Sport and QOL were the most responsive subscales after cartilage restoration surgery of the knee. Culture-based therapies (ACI/MACI) led to clinically relevant improvements in the KOOS Sport score compared with marrow stimulation and may be a more appropriate treatment in younger and more active individuals. There were no benefits to Mfx+Augment over Mfx alone in any of the KOOS subscales.

Current Advances in the Regeneration of Degenerated Articular Cartilage: A Literature Review on Tissue Engineering and Its Recent Clinical Translation

Functional ability is the basis of healthy aging. Articular cartilage degeneration is amongst the most prevalent degenerative conditions that cause adverse impacts on the quality of life; moreover, it represents a key predisposing factor to osteoarthritis (OA). Both the poor capacity of articular cartilage for self-repair and the unsatisfactory outcomes of available clinical interventions make innovative tissue engineering a promising therapeutic strategy for articular cartilage repair. Significant progress was made in this field; however, a marked heterogeneity in the applied biomaterials, biofabrication, and assessments is nowadays evident by the huge number of research studies published to date. Accordingly, this literature review assimilates the most recent advances in cell-based and cell-free tissue engineering of articular cartilage and also focuses on the assessments performed via various in vitro studies, ex vivo models, preclinical in vivo animal models, and clinical studies in order to provide a broad overview of the latest findings and clinical translation in the context of degenerated articular cartilage and OA.

The Fragility of Statistical Significance in Cartilage Restoration of the Knee: A Systematic Review of Randomized Controlled Trials

OBJECTIVE

The purpose of this study was to utilize fragility analysis to assess the robustness of randomized controlled trials (RCTs) evaluating the management of articular cartilage defects of the knee. We hypothesize that the cartilage restorative literature will be fragile with the reversal of only a few outcome events required to change statistical significance.

DESIGN

RCTs from 11 orthopedic journals indexed on PubMed from 2000 to 2020 reporting dichotomous outcome measures relating to the management of articular cartilage defects of the knee were included. The Fragility Index (FI) for each outcome was calculated through the iterative reversal of a single outcome event until significance was reversed. The Fragility Quotient (FQ) was calculated by dividing each FI by study sample size. Additional statistical analysis was performed to provide median FI and FQ across subgroups.

RESULTS

Nineteen RCTs containing 60 dichotomous outcomes were included for analysis. The FI and FQ of all outcomes was 4 (IQR 2-7) and 0.067 (IQR 0.034-0.096), respectively. The average number of patients lost to follow-up (LTF) was 3.9 patients with 15.8% of the included studies reporting LTF greater than or equal to 4, the FI of all included outcomes.

CONCLUSIONS

The orthopedic literature evaluating articular cartilage defects of the knee is fragile as the reversal of relatively few outcome events may alter the significance of statistical findings. We therefore recommend comprehensive fragility analysis and triple reporting of the P value, FI, and FQ to aid in the interpretation and contextualization of clinical findings reported in the cartilage restoration literature.

Porcine-Derived Collagen-Augmented Chondrogenesis Technique for Treating Knee Cartilage Defects

Articular cartilage is virtually incapable of self-healing in the event of a defect. Microfracture is the most frequently used bone marrow stimulation technique¹, but there is the limitation of unpredictable quality of the cartilage repair following bone marrow stimulation². To resolve the shortcomings of the microfracture technique, various reinforcing technologies have been developed, including the porcine-derived collagen-augmented chondrogenesis technique (C-ACT)³. The collagen gel utilized in that procedure is a product called CartiFill (Sewon Cellontech), made from highly purified pig-derived type-I collagen. It has been modified into an atelocollagen, by removing telopeptides, to virtually eliminate the risk of rejection. The collagen matrix provides not only a 3-dimensional structure for cartilage differentiation, but also mechanical support^3,4.

Description

Porcine-derived C-ACT is initiated by creating a mixture of atelocollagen, thrombin, and fibrinogen. First, thrombin is mixed with atelocollagen and placed in one arm of an assembled Y-shaped syringe, and fibrinogen is placed in the other arm. The articular cartilage defect site is confirmed in a routine arthroscopic procedure. The articular margin is debrided, and the calcified lesion is cleanly removed. Then, microfractures are created. After creating a more extended incision at the anteromedial portal, the microfracture site is prepared by removing moisture. The prepared atelocollagen mixture is applied to the defect site as a single layer, although a second layer can be formed 1 to 2 minutes later. After 5 minutes, the stability is verified by range of motion of the knee.Indications for this procedure include (1) cartilage defects in the knee, including knee osteoarthritis and knee traumatic arthritis; (2) knee osteoarthritis with a Kellgren-Lawrence grade of 3 or less; (3) hip-knee-ankle malalignment of <5° or a deformity that is able to be surgically corrected; and (4) knee stability, or instability that is able to be surgically corrected.Contraindications for this procedure include (1) patient or family history of autoimmune disease, (2) history of anaphylactic reaction, (3) history of hypersensitivity to an implant, (4) history of allergy to porcine or bovine protein, and (5) inflammatory arthritis such as rheumatoid and gouty arthritis.C-ACT is a procedure for cartilage repair, and the effects of this procedure can be limited in cases with a deep subchondral bone defect; however, there is no limit to the size of the cartilage defect in terms of patient selection for C-ACT.

Alternatives

There are several alternatives to C-ACT, ranging from the simple microfracture technique to autologous chondrocyte implantation⁵, matrix-induced autologous chondrocyte implantation⁶, autologous matrix-induced chondrogenesis⁷, osteochondral autograft transplantation⁸, and stem cell therapy. There are various ways to recover from an articular cartilage defect, but C-ACT does not require a 2-stage technique, as is necessary with both autologous chondrocyte implantation procedures. Therefore, C-ACT has the advantages of ease of operation and being a single-stage procedure^3,9.

Rationale

C-ACT can be classified as an upgraded version of microfracture, which is the most common treatment method for articular cartilage defects. With the microfracture technique, repaired cartilage is limited to fibrous cartilage and does not include hyaline cartilage^3,4. However, a recent study reported that C-ACT exhibited a superior quality of repaired cartilage compared with microfracture^3,4.

Expected Outcomes

Previous studies have reported favorable results with the use of C-ACT^3,4. Kim et al.⁴ compared atelocollagen augmentation with microfracture alone in patients undergoing medial opening wedge high tibial osteotomy for the treatment of medial compartment osteoarthritis. Although there was no clinical difference between the 2 groups, the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score and the International Cartilage Repair Society II score were superior in the atelocollagen augmentation group. In addition, the microfracture group formed fibrous-like cartilage compared with the hyaline-like cartilage created in the atelocollagen augmentation group. A recent multicenter randomized study compared the use of C-ACT and microfracture and found that C-ACT exhibited significantly better results in several MOCART subscores and quantitative T2 mapping, indicating a histologically superior form of repaired cartilage compared with microfracture³. According to recent research, microfracture is superior to autologous chondrocyte implantation in terms of cost-effectiveness¹⁰. Similar results appear to be applicable to C-ACT. C-ACT requires an additional $1,300 for material costs; however, C-ACT showed better cartilage regeneration on magnetic resonance imagining and histology^3,4, and higher rate of patients meeting the 20%-improvement rate in visual analogue scale pain scores at 24 months postoperatively compared with microfracture³. Long-term studies will be needed to assess whether histological superiority of C-ACT is reflected in meaningful improvements to clinical outcomes.

Important Tips

Debride all of the damaged cartilage to subchondral bone and remove the calcified layer without interfering with tissue repairTake special care when creating the atelocollagen mixture to ensure that it is accurately manufacturedDry the defect site with use of suction or gauze to aid in atelocollagen adhesion when applying atelocollagen.

Articular Cartilage Restoration Requires Cells, Scaffolds, Growth Factors, and Mechanical Stimulation

Tissue engineering requires cells, scaffolds, growth factors, and mechanical stimulation. In terms of cartilage restoration or repair, various innovative approaches are evolving, using host or allograft cells, biomimetic scaffolds, matrices, or membranes including hyaluronic acid, as well as diverse biological and growth factors. A current approach for the treatment of chondral or osteochondral defects enhances a microfracture procedure (introducing autologous, mesenchymal stem cells) with dehydrated micronized allograft extracellular matrix (scaffold), platelet-rich plasma (containing anabolic, anticatabolic, and anti-inflammatory growth factors), a fibrin glue sealant, and careful rehabilitation providing mechanical stimulation. Early results are encouraging; long-term outcomes including a larger number of study subjects remain to be reported.

Single-Stage Arthroscopic Cartilage Repair With Injectable Scaffold and BMAC

Injectable scaffold augmentation is a promising modality for single-stage cartilage repair. According to published studies, cartilage repair with scaffold augmentation has improved clinical outcomes, radiological fill, and histological repair compared with microfracture alone. Injectable scaffolds have the versatility to be used in large and irregularly shaped lesions. With correct preparation, they can be applied to lesions on the femoral condyle that may be vertical, or even inverted lesions such as those in the patella. They can be combined with bone marrow aspirate concentrate (BMAC) to provide mesenchymal stem cells (MSCs), thereby avoiding the need for microfracture. This protects the subchondral plate, preventing biomechanical alteration and potentially resulting in improved long-term outcomes. In this article, we demonstrate the utility of injectable scaffolds and their combination with BMAC.

Next-Generation Marrow Stimulation Technology for Cartilage Repair: Basic Science to Clinical Application

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Given the relatively high prevalence of full-thickness articular cartilage lesions, including in patients who are <40 years of age, and an inability to detect some of these lesions until the time of arthroscopy, there is value in performing a single-stage cartilage procedure such as marrow stimulation (MS).

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While the positive outcomes of first-generation MS (namely microfracture) have been observed to drop off after 24 months in several studies, improvements have been seen when compared with preoperative conditions for lesions that are 2 to 3 cm2 in size, and MS is considered to be a procedure with technical simplicity, fairly short surgical times, and relatively low morbidity. A recent study showed that autologous chondrocyte implantation (ACI) and osteochondral allograft (OCA) transplantation remain viable treatment options for chondral defects of the knee in the setting of failed MS.

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Basic science principles that have been elucidated in recent years include (1) the creation of vertical walls during defect preparation, (2) an increased depth of subchondral penetration, (3) a smaller awl diameter, and (4) an increased number of subchondral perforations, which are all thought to help resolve issues of access to the mesenchymal stromal cells (MSCs) and the subchondral bone structure/overgrowth issues.

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Pioneering and evolving basic science and clinical studies have led to next-generation clinical applications, such as a hyaluronic acid-based scaffold (ongoing randomized controlled trial [RCT]), an atelocollagen-based gel (as described in a recently published RCT), a micronized allogeneic cartilage scaffold (as described in a recently completed prospective cohort study), and a biosynthetic hydrogel that is composed of polyethylene glycol (PEG) diacrylate and denatured fibrinogen (as described in an ongoing prospective study).

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This review summarizes important points for defect preparation and the recent advances in MS techniques and identifies specific scaffolding augmentation strategies (e.g., mesenchymal augmentation and scaffold stimulation [MASS]) that have the capacity to advance cartilage regeneration in light of recent laboratory and clinical studies.

High-precision, gelatin-based, hybrid, bilayer scaffolds using melt electro-writing to repair cartilage injury

Articular cartilage injury is a common disease in the field of orthopedics. Because cartilage has poor self-repairing ability, medical intervention is needed. Using melt electro-writing (MEW) technology, tissue engineering scaffolds with high porosity and high precision can be prepared. However, ordinary materials, especially natural polymer materials, are difficult to print. In this study, gelatin was mixed with poly (lactic-co-glycolic acid) to prepare high-concentration and high-viscosity printer ink, which had good printability and formability. A composite scaffold with full-layer TGF-β1 loading mixed with hydroxyapatite was prepared, and the scaffold was implanted at the cartilage injury site; microfracture surgery was conducted to induce the mesenchyme in the bone marrow. Quality stem cells thereby promoted the repair of damaged cartilage. In summary, this study developed a novel printing method, explored the molding conditions based on MEW printing ink, and constructed a bioactive cartilage repair scaffold. The scaffold can use autologous bone marrow mesenchymal stem cells and induce their differentiation to promote cartilage repair.

Measuring Outcomes in Knee Articular Cartilage Pathology

Measuring outcomes following treatment of knee articular cartilage lesions is crucial to determine the natural history of disease and the efficacy of treatments. Outcome assessments for articular cartilage treatments can be clinical (based on failure, lack of healing, reoperation, need for arthroplasty), radiographic (X-ray, MRI), histologic, or patient reported and functional. The purpose of this review is to discuss the application and properties of patient-reported outcomes (PROs) with a focus on articular cartilage injuries and surgery in the knee. The most frequently used and validated PROs for knee articular cartilage studies include: the Knee injury and Osteoarthritis and Outcome Score, International Knee Documentation Committee Subjective Knee Form, and Lysholm score as knee-specific measures; the Marx Activity Rating Scale and Tegner Activity Scale as activity measures; and EQ-5D and SF-36/12 as generic quality-of-life measures. Incorporating these validated PROs in studies pertaining to knee articular cartilage lesions will allow researchers to fully capture clinically relevant outcomes that are most important to patients.

Editorial Commentary: Cartilage Restoration-What Is Currently Available?

In the past 30 years, bone marrow stimulation techniques such as microfracture (MF) have become a popular method to treat symptomatic focal articular cartilage lesions. Nonetheless, recent studies have not shown good long-term clinical outcomes, and MF has produced alterations in the subchondral bone architecture with degenerative changes. Autologous chondrocyte implantation (ACI) has shown good results at 20 years. Second- and third-generation ACI has shown superiority to MF and fewer complications than first-generation ACI. Each treatment option has its advantages and disadvantages. Recent research has shown that better filling of cartilage tissue occurs in patients treated with MF and collagen augmentation than in those treated with MF alone. Research from our clinic has shown that Hyaff scaffold combined with bone marrow aspirate concentrate in a 1-step technique yielded good results in patients with 10 years' follow-up. We believe that high-quality randomized controlled trials are necessary to directly compare all cartilage restoration procedures.