Poor osteochondral repair by a biomimetic collagen scaffold: 1- to 3-year clinical and radiological follow-up

The efficacy of autologous matrix-induced chondrogenesis (AMIC) for osteochondral lesions of the talus in the mid-long term: a systematic review and meta-analysis

PURPOSE

The objective of this study was to provide a comprehensive review of the existing literature regarding the treatment of osteochondral lesions of the talus (OLT) using autologous matrix-induced chondrogenesis (AMIC), while also discussing the mid-long term functional outcomes, complications, and surgical failure rate.

METHODS

We searched Embase, PubMed, and Web of Science for studies on OLT treated with AMIC with an average follow-up of at least 2 years. Publication information, patient data, functional scores, surgical failure rate, and complications were extracted.

RESULTS

A total of 15 studies were screened and included, with 12 case series selected for meta-analysis and 3 non-randomized controlled studies chosen for descriptive analysis. The improvements in the Visual Analog Scale (VAS), the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot, and Tegner scores at the last follow-up were (SMD = - 2.825, 95% CI - 3.343 to  - 2.306, P < 0.001), (SMD = 2.73, 95% CI 1.60 to 3.86, P < 0.001), (SMD = 0.85, 95% CI 0.5 to 1.2, P < 0.001) respectively compared to preoperative values. The surgery failure rate was 11% (95% CI 8-15%), with a total of 12 patients experiencing complications.

CONCLUSION

The use of AMIC demonstrates a positive impact on pain management, functional improvement, and mobility enhancement in patients with OLT. It is worth noting that the choice of stent for AMIC, patient age, and OLT size can influence the ultimate clinical outcomes. This study provides evidences supporting the safety and efficacy of AMIC as a viable treatment option in real-world medical practice.

A Biomimetic Osteochondral Scaffold Augmented With Filtered Bone Marrow Aspirate for the Treatment of Joint Surface Lesions in the Knee

BACKGROUND

Multilayered osteochondral scaffolds are becoming increasingly utilized for the repair of knee joint surface lesions (KJSLs). However, the literature on predictive factors is rather limited.

PURPOSE

To (1) evaluate the clinical outcomes and safety of a combined single-step approach using a biomimetic collagen-hydroxyapatite scaffold (CHAS) and filtered bone marrow aspirate (fBMA) for the treatment of KJSLs and (2) identify significant predictors of the treatment outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All patients who underwent surgery because of a KJSL (size ≥1.5 cm2; International Cartilage Regeneration & Joint Preservation Society grades 3-4) using the combination above were selected from a hospital registry database (100 patients; minimum 2-year follow-up). Patient characteristics, medical history, knee joint and lesion status, intraoperative details, and cellular parameters of the injected fBMA were collected. The arthroscopic evaluation of chondral and meniscal tissue quality in all knee compartments was performed using the Chondropenia Severity Score. Treatment outcomes were determined clinically using patient-reported outcome measures (Knee Injury and Osteoarthritis Outcome Score, EuroQol-5 Dimensions-3 Levels, EuroQol-Visual Analog Scale, and Tegner Activity Scale) and by assessing the occurrence of serious adverse events and graft failure. Multivariable regression analysis was performed to identify significant predictors of the treatment outcomes.

RESULTS

At a mean follow-up of 54.2 ± 19.4 months, 78 (87%) patients completed the questionnaires with significant improvements toward the baseline (P < .00625): KOOS Pain subscale from 62 ± 17 to 79 ± 18, KOOS Total score from 57 ± 16 to 70 ± 20, EuroQol-Visual Analog Scale from 61 ± 21 to 76 ± 16, EuroQol-5 Dimensions-3 Levels from 0.57 ± 0.20 to 0.80 ± 0.21, and Tegner Activity Scale from 2.8 ± 1.5 to 3.9 ± 1.9. The graft failure rate was 4%. A longer duration of preoperative symptoms, previous surgery, larger lesions, older age, and female sex were the main negative predictors for the treatment outcomes. The Chondropenia Severity Score and the number of fibroblast colony-forming units in fBMA positively influenced some of the clinical results and safety.

CONCLUSION

A CHAS augmented with fBMA proved to be an adequate and safe approach for the treatment of KJSLs up to midterm follow-up. Based on the subanalysis of predictive factors, the surgical intervention should be performed in a timely and precise manner to prevent lesion enlargement, deterioration of the general knee cartilage status, and recurrent surgical procedures, especially in older and female patients. When a CHAS is used, the quantity of MSCs seems to play a role in augmentation.

REGISTRATION

NCT06078072 (ClinicalTrials.gov identifier).

Effects of self-assembled type II collagen fibrils on the morphology and growth of pre-chondrogenic ATDC5 cells

Objective

Although type II collagen could have marked potential for developing cartilage tissue engineering (CTE) scaffolds, its erratic supply and viscous nature have limited these studies, and there are no studies on the use of marine-derived type II collagen fibrils for CTE scaffold materials. In this study, we aimed to generate a fibril-based, thin-layered scaffold from marine-derived type II collagen and investigate its chondrogenic potential.

Methods

Time-lapse observations revealed the cell adhesion process. The Cell Counting Kit-8 (CCK-8) assay, light microscopy, and scanning electron microscopy were performed to detect proliferation and filopodium morphology. Alcian blue staining was used to show the deposition of extracellular secretions, and qRT-PCR was performed to reveal the expression levels of chondrogenesis-related genes.

Results

The cell adhesion speed was similar in both fibril-coated and control molecule-coated groups, but the cellular morphology, proliferation, and chondrogenesis activity differed. On fibrils, more elongated finer filopodia showed inter-cell communications, whereas the slower proliferation suggested an altered cell cycle. Extracellular secretions occurred before day 14 and continued until day 28 on fibrils, and on fibrils, the expression of the chondrogenesis-related genes Sox9 (p ​< ​0.001), Col10a1 (p ​< ​0.001), Acan (p ​< ​0.001), and Col2a1 (p ​= ​0.0049) was significantly upregulated on day 21.

Conclusion

Marine-derived type II collagen was, for the first time, fabricated into a fibril state. It showed rapid cellular affinity and induced chondrogenesis with extracellular secretions. We presented a new model for studying chondrogenesis in vitro and a potential alternative material for cell-laden CTE research.

Type II collagen scaffolds repair critical-sized osteochondral defects under induced conditions of osteoarthritis in rat knee joints via inhibiting TGF-β-Smad1/5/8 signaling pathway

The bidirectional relationship between osteochondral defects (OCD) and osteoarthritis (OA), with each condition exacerbating the other, makes OCD regeneration in the presence of OA challenging. Type II collagen (Col2) is important in OCD regeneration and the management of OA, but its potential applications in cartilage tissue engineering are significantly limited. This study investigated the regeneration capacity of Col2 scaffolds in critical-sized OCDs under surgically induced OA conditions and explored the underlying mechanisms that promoted OCD regeneration. Furthermore, the repair potential of Col2 scaffolds was validated in over critical-sized OCD models. After 90 days or 150 days since scaffold implantation, complete healing was observed histologically in critical-sized OCD, evidenced by the excellent integration with surrounding native tissues. The newly formed tissue biochemically resembled adjacent natural tissue and exhibited comparable biomechanical properties. The regenerated OA tissue demonstrated lower expression of genes associated with cartilage degradation than native OA tissue but comparable expression of genes related to osteochondral anabolism compared with normal tissue. Additionally, transcriptome and proteome analysis revealed the hindrance of TGF-β-Smad1/5/8 in regenerated OA tissue. In conclusion, the engrafting of Col2 scaffolds led to the successful regeneration of critical-sized OCDs under surgically induced OA conditions by inhibiting the TGF-β-Smad1/5/8 signaling pathway.

Nanotechnology development in surgical applications: recent trends and developments

This paper gives a detailed analysis of nanotechnology's rising involvement in numerous surgical fields. We investigate the use of nanotechnology in orthopedic surgery, neurosurgery, plastic surgery, surgical oncology, heart surgery, vascular surgery, ophthalmic surgery, thoracic surgery, and minimally invasive surgery. The paper details how nanotechnology helps with arthroplasty, chondrogenesis, tissue regeneration, wound healing, and more. It also discusses the employment of nanomaterials in implant surfaces, bone grafting, and breast implants, among other things. The article also explores various nanotechnology uses, including stem cell-incorporated nano scaffolds, nano-surgery, hemostasis, nerve healing, nanorobots, and diagnostic applications. The ethical and safety implications of using nanotechnology in surgery are also addressed. The future possibilities of nanotechnology are investigated, pointing to a possible route for improved patient outcomes. The essay finishes with a comment on nanotechnology's transformational influence in surgical applications and its promise for future breakthroughs.

Multiphasic scaffolds for the repair of osteochondral defects: Outcomes of preclinical studies

Osteochondral defects are caused by injury to both the articular cartilage and subchondral bone within skeletal joints. They can lead to irreversible joint damage and increase the risk of progression to osteoarthritis. Current treatments for osteochondral injuries are not curative and only target symptoms, highlighting the need for a tissue engineering solution. Scaffold-based approaches can be used to assist osteochondral tissue regeneration, where biomaterials tailored to the properties of cartilage and bone are used to restore the defect and minimise the risk of further joint degeneration. This review captures original research studies published since 2015, on multiphasic scaffolds used to treat osteochondral defects in animal models. These studies used an extensive range of biomaterials for scaffold fabrication, consisting mainly of natural and synthetic polymers. Different methods were used to create multiphasic scaffold designs, including by integrating or fabricating multiple layers, creating gradients, or through the addition of factors such as minerals, growth factors, and cells. The studies used a variety of animals to model osteochondral defects, where rabbits were the most commonly chosen and the vast majority of studies reported small rather than large animal models. The few available clinical studies reporting cell-free scaffolds have shown promising early-stage results in osteochondral repair, but long-term follow-up is necessary to demonstrate consistency in defect restoration. Overall, preclinical studies of multiphasic scaffolds show favourable results in simultaneously regenerating cartilage and bone in animal models of osteochondral defects, suggesting that biomaterials-based tissue engineering strategies may be a promising solution.

Aragonite-Based Scaffold Versus Microfracture and Debridement for the Treatment of Knee Chondral and Osteochondral Lesions: Results of a Multicenter Randomized Controlled Trial

BACKGROUND

Lesions of the articular cartilage, with or without involvement of the subchondral bone, are a common cause of pain and dysfunction in the knee. Although several treatment options have been developed, the majority of previous clinical trials examined patients with isolated or focal midsized defects, which rarely represent the condition found in the general population. Rather, cartilage lesions are often associated with the presence of mild to moderate osteoarthritic changes.

PURPOSE

The present multicenter randomized controlled trial compared the clinical and radiographic outcomes of an aragonite-based osteochondral implant with a control group (arthroscopic debridement/microfractures) in patients affected by joint surface lesions of the knee, including those with concurrent mild to moderate osteoarthritis.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 251 patients were enrolled in 26 medical centers according to the following criteria: age 21 to 75 years, up to 3 cartilage defects of International Cartilage Regeneration & Joint Preservation Society grade 3a or above located on the femoral condyles and/or trochlea, total treatable area from 1 to 7 cm², bony defect depth ≤8 mm, and knee osteoarthritis grade 0 to 3 according to Kellgren-Lawrence score. Patients were randomized to the aragonite-based implant or debridement/microfracture control arm in a 2:1 ratio. Evaluation was performed at 6, 12, 18, and 24 months based on overall Knee injury and Osteoarthritis Outcome Score (KOOS) as the primary endpoint, and the KOOS subscales (Pain, Quality of Life, Activities of Daily Living), percentage of responders, and International Knee Documentation Committee (IKDC) subjective score as the secondary endpoints. Patients also underwent magnetic resonance imaging evaluation at 12 and 24 months to assess defect fill grade. Failures (ie, need for any secondary treatment) and adverse events were also recorded.

RESULTS

The implant group showed a statistically superior outcome in the primary endpoint and all secondary endpoints at each follow-up. The magnitude of improvement in the implant group was twice as large as that in the control group in terms of mean KOOS improvement at 2 years. Responder rate (defined as at least a 30-point improvement in overall KOOS) was 77.8% in the implant group as opposed to 33.6% in the control (P < .0001). Statistically superior results were seen in the IKDC score as well. At 24 months, 88.5% of the implanted group had at least 75% defect fill on magnetic resonance imaging as compared with 30.9% of controls (P < .0001). The failure rate was 7.2% for the implant group versus 21.4% for control.

CONCLUSION

This aragonite-based scaffold was safe and effective in the treatment of chondral and osteochondral lesions in the knee, including patients with mild to moderate osteoarthritis, and provided superior outcomes as compared with the control group.

REGISTRATION

NCT03299959 (ClinicalTrials.gov identifier).

Effectiveness of BMP-2 and PDGF-BB Adsorption onto a Collagen/Collagen-Magnesium-Hydroxyapatite Scaffold in Weight-Bearing and Non-Weight-Bearing Osteochondral Defect Bone Repair: In Vitro, Ex Vivo and In Vivo Evaluation

Despite promising clinical results in osteochondral defect repair, a recently developed bi-layered collagen/collagen-magnesium-hydroxyapatite scaffold has demonstrated less optimal subchondral bone repair. This study aimed to improve the bone repair potential of this scaffold by adsorbing bone morphogenetic protein 2 (BMP-2) and/or platelet-derived growth factor-BB (PDGF-BB) onto said scaffold. The in vitro release kinetics of BMP-2/PDGF-BB demonstrated that PDGF-BB was burst released from the collagen-only layer, whereas BMP-2 was largely retained in both layers. Cell ingrowth was enhanced by BMP-2/PDFG-BB in a bovine osteochondral defect ex vivo model. In an in vivo semi-orthotopic athymic mouse model, adding BMP-2 or PDGF-BB increased tissue repair after four weeks. After eight weeks, most defects were filled with bone tissue. To further investigate the promising effect of BMP-2, a caprine bilateral stifle osteochondral defect model was used where defects were created in weight-bearing femoral condyle and non-weight-bearing trochlear groove locations. After six months, the adsorption of BMP-2 resulted in significantly less bone repair compared with scaffold-only in the femoral condyle defects and a trend to more bone repair in the trochlear groove. Overall, the adsorption of BMP-2 onto a Col/Col-Mg-HAp scaffold reduced bone formation in weight-bearing osteochondral defects, but not in non-weight-bearing osteochondral defects.

Multilayered biomimetic scaffolds for cartilage repair of the talus. A systematic review of the literature

OBJECTIVE

The aim of the present review was to analyze the available evidence in the literature on the clinical and radiological outcomes of multilayered biomimetic scaffolds in the treatment of osteochondral lesions of the talus (OLTs).

DESIGN

A systematic search was performed in three databases to identify clinical trials, where the multilayered biomimetic scaffolds were used for the treatment of OLTs. The PRISMA guidelines were followed. Qualitative analysis of the relevant data of the included studies was executed. The methodological quality of the analyzed studies was assessed with a modified Coleman Methodology Score (CMS).

RESULTS

A total of 10 studies with 87 patients were included in the analysis. Only three multilayered biomimetic scaffolds have been investigated in clinical trials for the treatment of OLTs. The worst clinical and radiological outcomes, as well as safety profile were observed for the TruFit scaffold (Smith & Nephew, Andover, MA, USA), which had already been withdrawn from the market. The other two scaffolds (MaioRegen, Finceramica, Italy; Agili-C, Cartiheal, Israel) performed significantly better in the majority of the reviewed studies, especially in the clinical aspect. The radiological findings, the improvements of MOCART scores, the completeness of lesions' fill, and the structure of regenerated tissue were much more inconsistent.

CONCLUSIONS

Two of the multilayered biomimetic scaffolds demonstrated an adequate potential in the treatment of complex OLTs. However, limited studies availability and their low level of medical evidence request further high-level investigations before the clinical decision making for such scaffolds in the treatment of OLTs can be defined.

Recent Advances in Hydroxyapatite-Based Biocomposites for Bone Tissue Regeneration in Orthopedics

Bone tissue is a nanocomposite consisting of an organic and inorganic matrix, in which the collagen component and the mineral phase are organized into complex and porous structures. Hydroxyapatite (HA) is the most used ceramic biomaterial since it mimics the mineral composition of the bone in vertebrates. However, this biomimetic material has poor mechanical properties, such as low tensile and compressive strength, which make it not suitable for bone tissue engineering (BTE). For this reason, HA is often used in combination with different polymers and crosslinkers in the form of composites to improve their mechanical properties and the overall performance of the implantable biomaterials developed for orthopedic applications. This review summarizes recent advances in HA-based biocomposites for bone regeneration, addressing the most widely employed inorganic matrices, the natural and synthetic polymers used as reinforcing components, and the crosslinkers added to improve the mechanical properties of the scaffolds. Besides presenting the main physical and chemical methods in tissue engineering applications, this survey shows that HA biocomposites are generally biocompatible, as per most in vitro and in vivo studies involving animal models and that the results of clinical studies on humans sometimes remain controversial. We believe this review will be helpful as introductory information for scientists studying HA materials in the biomedical field.

Recent Advances and Perspective of Nanotechnology-Based Implants for Orthopedic Applications

Bioimplant engineering strives to provide biological replacements for regenerating, retaining, or modifying injured tissues and/or organ function. Modern advanced material technology breakthroughs have aided in diversifying ingredients used in orthopaedic implant applications. As such, nanoparticles may mimic the surface features of real tissues, particularly in terms of wettability, topography, chemistry, and energy. Additionally, the new features of nanoparticles support their usage in enhancing the development of various tissues. The current study establishes the groundwork for nanotechnology-driven biomaterials by elucidating key design issues that affect the success or failure of an orthopaedic implant, its antibacterial/antimicrobial activity, response to cell attachment propagation, and differentiation. The possible use of nanoparticles (in the form of nanosized surface or a usable nanocoating applied to the implant’s surface) can solve a number of problems (i.e., bacterial adhesion and corrosion resilience) associated with conventional metallic or non-metallic implants, particularly when implant techniques are optimised. Orthopaedic biomaterials’ prospects (i.e., pores architectures, 3D implants, and smart biomaterials) are intriguing in achieving desired implant characteristics and structure exhibiting stimuli-responsive attitude. The primary barriers to commercialization of nanotechnology-based composites are ultimately discussed, therefore assisting in overcoming the constraints in relation to certain pre-existing orthopaedic biomaterials, critical factors such as quality, implant life, treatment cost, and pain alleviation.

Biomaterials for meniscus and cartilage in knee surgery: state of the art

Meniscus and cartilage injuries of the knee joint lead to cartilage degeneration and osteoarthritis (OA). The research on biomaterials and artificial implants as substitutes in reconstruction and regeneration has become a main international focus in order to solve clinical problems such as irreparable meniscus injury, postmeniscectomy syndrome, osteochondral lesions and generalised chronic OA. In this review, we provide a summary of biomaterials currently used in clinical practice as well as state-of-the-art tissue engineering strategies and technologies that are developed for articular cartilage and meniscus repair and regeneration. The literature was reviewed over the last 5 years on clinically used meniscus and cartilage repair biomaterials, such as Collagen Meniscal Implant, Actifit, NUsurface, TruFit, Agili-C and MaioRegen. There are clinical advantages for these biomaterials and the application of these treatment options should be considered individually. Standardised evaluation protocols are needed for biological and mechanical assessment and comparison between different scaffolds, and long-term randomised independent clinical trials with large study numbers are needed to provide more insight into the use of these biomaterials. Surgeons should become familiar and stay up to date with evolving repair options to improve their armamentarium for meniscal and cartilage defects.

The immune microenvironment in cartilage injury and repair

The ability of articular cartilage to repair itself is limited because it lacks blood vessels, nerves, and lymph tissue. Once damaged, it can lead to joint swelling and pain, accelerating the progression of osteoarthritis. To date, complete regeneration of hyaline cartilage exhibiting mechanical properties remains an elusive goal, despite the many available technologies. The inflammatory milieu created by cartilage damage is critical for chondrocyte death and hypertrophy, extracellular matrix breakdown, ectopic bone formation, and progression of cartilage injury to osteoarthritis. In the inflammatory microenvironment, mesenchymal stem cells (MSCs) undergo aberrant differentiation, and chondrocytes begin to convert or dedifferentiate into cells with a fibroblast phenotype, thereby resulting in fibrocartilage with poor mechanical qualities. All these factors suggest that inflammatory problems may be a major stumbling block to cartilage repair. To produce a milieu conducive to cartilage repair, multi-dimensional management of the joint inflammatory microenvironment in place and time is required. Therefore, this calls for elucidation of the immune microenvironment of cartilage repair after injury. This review provides a brief overview of: (1) the pathogenesis of cartilage injury; (2) immune cells in cartilage injury and repair; (3) effects of inflammatory cytokines on cartilage repair; (4) clinical strategies for treating cartilage defects; and (5) strategies for targeted immunoregulation in cartilage repair. STATEMENT OF SIGNIFICANCE: Immune response is increasingly considered the key factor affecting cartilage repair. It has both negative and positive regulatory effects on the process of regeneration and repair. Proinflammatory factors are secreted in large numbers, and necrotic cartilage is removed. During the repair period, immune cells can secrete anti-inflammatory factors and chondrogenic cytokines, which can inhibit inflammation and promote cartilage repair. However, inflammatory factors persist, which accelerate the degradation of the cartilage matrix. Furthermore, in an inflammatory microenvironment, MSCs undergo abnormal differentiation, and chondrocytes begin to transform or dedifferentiate into fibroblast-like cells, forming fibrocartilage with poor mechanical properties. Consequently, cartilage regeneration requires multi-dimensional regulation of the joint inflammatory microenvironment in space and time to make it conducive to cartilage regeneration.

Treatment of Juvenile Knee Osteochondritis Dissecans with a Cell-Free Biomimetic Osteochondral Scaffold: Clinical and MRI Results at Mid-Term Follow-up

OBJECTIVE

Osteochondral surgical procedures have been described for the treatment of unfixable osteochondritis dissecans (OCD), but only few of them have been studied for juvenile OCD (JOCD) lesions. A cell-free biomimetic osteochondral scaffold showed positive results in adult patients. The aim of this study was to evaluate the results of this scaffold for the treatment of knee JOCD at mid-term follow-up.

DESIGN

Twenty patients (14 males, 6 females) were included in this study. Mean age was 16.2 ± 1.4 years, average defect size was 3.2 ± 1.8 cm², and mean symptoms duration was 20.2 ± 17.9 months. After the implantation of the osteochondral collagen-hydroxyapatite scaffold (Maioregen, Fin-Ceramica, Faenza, Italy), patients were evaluated preoperatively and prospectively at 1, 2, and at final mean follow-up of 6 years (range 5-7 years) with International Knee Documentation Committee (IKDC) subjective and objective, Tegner, and EuroQol visual analogue scale (VAS) scores. MRI evaluation was performed with the MOCART 2.0 score.

RESULTS

All scores showed a significant improvement. IKDC subjective score went from 50.3 ± 17.4 preoperative score to 75.3 ± 14.6 at 1 year (P = 0.002), 80.8 ± 14.6 at 2 years and 85.0 ± 9.3 at 6 years. The Tegner score improved from the preoperative evaluation of 2.6 ± 1.4 to 5.5 ± 2.0 at 6 years (P < 0.0005), although without reaching the level registered before the onset of symptoms. A longer symptoms duration influenced negatively IKDC subjective and Tegner scores up to 2 years (P = 0.003 and P = 0.002, respectively) but did not affect the final outcome. Lesion size did not affect the final result. The MOCART 2.0 score showed a significant improvement between 1-year and final follow-up, but with persisting subchondral alterations.

CONCLUSIONS

This study demonstrated a clinical improvement stable over time with a high survival rate, although with persisting abnormal MRI findings, especially at subchondral bone level. This procedure can be considered a suitable option for the treatment of young patients affected by knee OCD. Level of evidence. Case series, level IV.

Particulated Cartilage for Chondral and Osteochondral Repair: A Review

INTRODUCTION

Injuries to articular cartilage have a poor spontaneous repair potential and no gold standard treatment exist. Particulated cartilage, both auto- and allograft, is a promising new treatment method that circumvents the high cost of scaffold- and cell-based treatments.

MATERIALS AND METHODS

A comprehensive database search on particulated cartilage was performed.

RESULTS

Fourteen animal studies have found particulated cartilage to be an effective treatment for cartilage injuries. Many studies suggest that juvenile cartilage has increased regenerative potential compared to adult cartilage. Sixteen clinical studies on 4 different treatment methods have been published. (1) CAIS, particulated autologous cartilage in a scaffold, (2) Denovo NT, juvenile human allograft cartilage embedded in fibrin glue, (3) autologous cartilage chips-with and without concomitant bone grafting, and (4) augmented autologous cartilage chips.

CONCLUSION

Implantation of allogeneic and autologous particulated cartilage provides a low cost and effective treatment alternative to microfracture and autologous chondrocyte implantation. The methods are promising, but large randomized controlled studies are needed.

Osteochondral Lesions of the Talus: A Review on Talus Osteochondral Injuries, Including Osteochondritis Dissecans

This is a review on talus osteochondritis dissecans and talus osteochondral lesions. A majority of the osteochondral lesions are associated with trauma while the cause of pure osteochondritis dissecans is still much discussed with a possible cause being repetitive microtraumas associated with vascular disturbances causing subchondral bone necrosis and disability. Symptomatic nondisplaced osteochondral lesions can often be treated conservatively in children and adolescents while such treatment is less successful in adults. Surgical treatment is indicated when there is an unstable cartilage fragment. There are a large number of different operative technique options with no number one technique to be recommended. Most techniques have been presented in level II to IV studies with a low number of patients with short follow ups and few randomized comparisons exist. The actual situation in treating osteochondral lesions in the ankle is presented and discussed.

The MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) 2.0 Knee Score and Atlas

OBJECTIVE

Since the first introduction of the MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score, significant progress has been made with regard to surgical treatment options for cartilage defects, as well as magnetic resonance imaging (MRI) of such defects. Thus, the aim of this study was to introduce the MOCART 2.0 knee score - an incremental update on the original MOCART score - that incorporates this progression.

MATERIALS AND METHODS

The volume of cartilage defect filling is now assessed in 25% increments, with hypertrophic filling of up to 150% receiving the same scoring as complete repair. Integration now assesses only the integration to neighboring native cartilage, and the severity of surface irregularities is assessed in reference to cartilage repair length rather than depth. The signal intensity of the repair tissue differentiates normal signal, minor abnormal, or severely abnormal signal alterations. The assessment of the variables "subchondral lamina," "adhesions," and "synovitis" was removed and the points were reallocated to the new variable "bony defect or bony overgrowth." The variable "subchondral bone" was renamed to "subchondral changes" and assesses minor and severe edema-like marrow signal, as well as subchondral cysts or osteonecrosis-like signal. Overall, a MOCART 2.0 knee score ranging from 0 to 100 points may be reached. Four independent readers (two expert readers and two radiology residents with limited experience) assessed the 3 T MRI examinations of 24 patients, who had undergone cartilage repair of a femoral cartilage defect using the new MOCART 2.0 knee score. One of the expert readers and both inexperienced readers performed two readings, separated by a four-week interval. For the inexperienced readers, the first reading was based on the evaluation sheet only. For the second reading, a newly introduced atlas was used as an additional reference. Intrarater and interrater reliability was assessed using intraclass correlation coefficients (ICCs) and weighted kappa statistics. ICCs were interpreted according to Koo and Li; weighted kappa statistics were interpreted according to the criteria of Landis and Koch.

RESULTS

The overall intrarater (ICC = 0.88, P < 0.001) as well as the interrater (ICC = 0.84, P < 0.001) reliability of the expert readers was almost perfect. Based on the evaluation sheet of the MOCART 2.0 knee score, the overall interrater reliability of the inexperienced readers was poor (ICC = 0.34, P < 0.019) and improved to moderate (ICC = 0.59, P = 0.001) with the use of the atlas.

CONCLUSIONS

The MOCART 2.0 knee score was updated to account for changes in the past decade and demonstrates almost perfect interrater and intrarater reliability in expert readers. In inexperienced readers, use of the atlas may improve interrater reliability and, thus, increase the comparability of results across studies.

Articular cartilage and osteochondral tissue engineering techniques: Recent advances and challenges

In spite of the considerable achievements in the field of regenerative medicine in the past several decades, osteochondral defect regeneration remains a challenging issue among diseases in the musculoskeletal system because of the spatial complexity of osteochondral units in composition, structure and functions. In order to repair the hierarchical tissue involving different layers of articular cartilage, cartilage-bone interface and subchondral bone, traditional clinical treatments including palliative and reparative methods have showed certain improvement in pain relief and defect filling. It is the development of tissue engineering that has provided more promising results in regenerating neo-tissues with comparable compositional, structural and functional characteristics to the native osteochondral tissues. Here in this review, some basic knowledge of the osteochondral units including the anatomical structure and composition, the defect classification and clinical treatments will be first introduced. Then we will highlight the recent progress in osteochondral tissue engineering from perspectives of scaffold design, cell encapsulation and signaling factor incorporation including bioreactor application. Clinical products for osteochondral defect repair will be analyzed and summarized later. Moreover, we will discuss the current obstacles and future directions to regenerate the damaged osteochondral tissues.

Collagen type II: From biosynthesis to advanced biomaterials for cartilage engineering

Collagen type II is the major constituent of cartilage tissue. Yet, cartilage engineering approaches are primarily based on collagen type I devices that are associated with suboptimal functional therapeutic outcomes. Herein, we briefly describe cartilage's development and cellular and extracellular composition and organisation. We also provide an overview of collagen type II biosynthesis and purification protocols from tissues of terrestrial and marine species and recombinant systems. We then advocate the use of collagen type II as a building block in cartilage engineering approaches, based on safety, efficiency and efficacy data that have been derived over the years from numerous in vitro and in vivo studies.

Osteochondral tissue engineering: Perspectives for clinical application and preclinical development

The treatment of osteochondral defects (OCD) remains challenging. Among currently available surgical treatments for OCDs, scaffold-based treatments are promising to regenerate the osteochondral unit. However, there is still no consensus regarding the clinical effectiveness of these scaffold-based therapies for OCDs. Previous reviews have described the gradient physiological characteristics of osteochondral tissue and gradient scaffold design for OCD, tissue engineering strategies, biomaterials, and fabrication technologies. However, the discussion on bridging the gap between the clinical need and preclinical research is still limited, on which we focus in the present review, providing an insight into what is currently lacking in tissue engineering methods that failed to yield satisfactory outcomes, and what is needed to further improve these techniques. Currently available surgical treatments for OCDs are firstly summarized, followed by a comprehensive review on experimental animal studies in recent 5 years on osteochondral tissue engineering. The review will then conclude with what is currently lacking in these animal studies and the recommendations that would help enlighten the community in developing more clinically relevant implants.

The translational potential of this article

This review is attempting to summarize the lessons from clinical and preclinical failures, providing an insight into what is currently lacking in TE methods that failed to yield satisfactory outcomes, and what is needed to further improve these implants.

Cell-Free Biomimetic Osteochondral Scaffold for the Treatment of Knee Lesions: Clinical and Imaging Results at 10-Year Follow-up

BACKGROUND

Cell-free devices have been introduced to restore osteochondral defects, avoiding the limitations of cell-based procedures. Among these, an osteochondral scaffold made of type I collagen and hydroxyapatite has been investigated with promising results up to medium-term follow-up. However, the clinical and imaging results over time still need to be documented.

PURPOSE

To evaluate the clinical outcome and tissue maturation at long-term follow-up after the implantation of the osteochondral scaffold.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 24 patients (7 women, 17 men; age, 36 ± 9.5 years) underwent surgical implantation of the osteochondral scaffold and were prospectively evaluated before surgery, at 2-, 5-, and 10-year follow-up. The mean defect size was 2.9 ± 1.4 cm². Patients were evaluated using the International Knee Documentation Committee (IKDC) subjective and objective scores, and the activity level was documented with the Tegner score. Magnetic resonance imaging (MRI) evaluation involved the use of the magnetic resonance observation of cartilage repair tissue score combined with 5 more variables focused on the bone layer.

RESULTS

A statistically significant improvement of all clinical scores was documented from the baseline to the final evaluation. The IKDC subjective score improved from the preoperative level to 2 years (41 ± 13.2 and 77.1 ± 14.6, respectively) (P < .0005), with stable results up to 10 years (77.4 ± 19.4). The IKDC objective score changed from 52% of normal and nearly normal knees before the treatment to 84% at 10 years (P < .0005). Tegner sports activity at the final evaluation (3.8 ± 1.7) was higher compared with the preoperative level (1.6 ± 1.1; P < .05), but it remained significantly lower compared with the preinjury level (5.5 ± 2.6; P < .05). Treatment failed in 1 patient. Persisting graft alterations were observed on MRI scans, although without correlating with the clinical outcome.

CONCLUSION

The regenerative potential of this scaffold is limited, as demonstrated by the signal alterations persisting over time on MRI scans. On the other hand, the clinical improvement was significant and stable over time both in terms of subjective and objective outcomes, including activity level, with overall good results.

Multi-layer cell-free scaffolds for osteochondral defects of the knee: a systematic review and meta-analysis of clinical evidence

Purpose

The aim of this study was to analyze the clinical results provided by multi-layer cell-free scaffolds for the treatment of knee osteochondral defects.

Methods

A systematic review was performed on PubMed, Web of Science, and Cochrane to identify studies evaluating the clinical efficacy of cell-free osteochondral scaffolds for knee lesions. A meta-analysis was performed on articles reporting results of the International Knee Documentation Committee (IKDC) and Tegner scores. The scores were analyzed as improvement from baseline to 1, 2, and ≥ 3 years of follow-up. The modified Coleman Methodology Score was used to assess the study methodology.

Results

A total of 34 studies (1022 patients) with a mean follow-up of 35 months was included. Only three osteochondral scaffolds have been investigated in clinical trials: while TruFit® has been withdrawn from the market for the questionable results, the analysis of MaioRegen and Agili-C™ provided clinical improvements at 1, 2, and ≥ 3 years of follow-up (all significantly higher than the baseline, p < 0.05), although with a limited recovery of the sport-activity level. A low rate of adverse events and an overall failure rate of 7.0% were observed, but the overall evidence level of the available studies is limited.

Conclusions

Multi-layer scaffolds may provide clinical benefits for the treatment of knee osteochondral lesions at short- and mid-term follow-up and with a low number of failures, although the sport-activity level obtained seems to be limited. Further research with high-level studies is needed to confirm the role of multi-layer scaffold for the treatment of knee osteochondral lesions.

Complex Osteochondral Lesions of the Talus Treated With a Novel Bi-Phasic Aragonite-based Implant

To present initial results of a novel, bi-phasic, porous, biodegrade, and cell-free aragonite-based scaffold for treating complex osteochondral lesions of the talus (OLT). Four subjects (2 males and 2 females; 34-61 years old) were operated on their ankles due to chronic and deep OLT-Hepple grades 4 or 5 (1.8-2.2 cm²). Three subjects had OLT on the medial central trochlea, and 1 had a combined medial and lateral lesions. OLT were exposed through medial malleolus osteotomy, with an additional lateral arthrotomy in the combined lesions. Bi-phasic porous osteochondral scaffolds (single implant or 2 implants) were implanted in a press-fit manner using a designated surgical toolset. Treatment outcome was followed clinically (Foot and Ankle Outcome Score, EQ-5D 3L, Tegner activity scale) and by medical imaging (radiographs, magnetic resonance imaging) from 18 to 32 months. All Foot and Ankle Outcome Score values increased from preoperative to final follow-up values (Symptoms 62 to 71, Pain 53 to 84, ADL 60 to 89, Sport 19 to 65, and QoL 18 to 47). EQ-5D 3L increased from 0.59 to 0.76, and Tegner activity values increased from 1.5 to 3. Kellgren-Lawrence ankle radiographic scores remained stable (2 to 2). Postoperative MR evaluation demonstrated cartilage defect fill of 75% to 100% respect to the native cartilage in 3 subjects (4 OLTs), while 1 lesion was filled 25% to 50%. No graft related serious adverse events or graft failures were reported. The use of a bi-phasic osteochondral biodegradable aragonite-based scaffold in the treatment of complex OLT during the reported period presented positive and promising clinical and radiologic outcome, without serious adverse events or graft failures.

Gradient scaffolds for osteochondral tissue engineering and regeneration

The tissue engineering approach for repairing osteochondral (OC) defects involves the fabrication of a biological tissue scaffold that mimics the physiological properties of natural OC tissue (e.g., the gradient transition between the cartilage surface and the subchondral bone). The OC tissue scaffolds described in many research studies exhibit a discrete gradient (e.g., a biphasic or tri/multiphasic structure) or a continuous gradient to mimic OC tissue attributes such as biochemical composition, structure, and mechanical properties. One advantage of a continuous gradient scaffold over biphasic or tri/multiphasic tissue scaffolds is that it more closely mimics natural OC tissue since there is no distinct interface between each layer. Although research studies to this point have yielded good results related to OC regeneration with tissue scaffolds, differences between engineered scaffolds and natural OC tissue remain; due to these differences, current clinical therapies to repair OC defects with engineered scaffolds have not been successful. This paper provides an overview of both discrete and continuous gradient OC tissue scaffolds in terms of cell type, scaffold material, microscale structure, mechanical properties, fabrication methods, and scaffold stimuli. Fabrication of gradient scaffolds with three-dimensional (3D) printing is given special emphasis due to its ability to accurately control scaffold pore geometry. Moreover, the application of computational modeling in OC tissue engineering is considered; for example, efforts to optimize the scaffold structure, mechanical properties, and physical stimuli generated within the scaffold-bioreactor system to predict tissue regeneration are considered. Finally, challenges associated with the repair of OC defects and recommendations for future directions in OC tissue regeneration are proposed.

Particulated Autologous Chondral-Platelet-Rich Plasma Matrix Implantation (PACI) for Treatment of Full-Thickness Cartilage Osteochondral Defects

Articular hyaline cartilage injuries can occur as a result of either traumatic of progressive degeneration. When the articular cartilage in a joint is damaged, it can cause joint pain and dysfunction, predisposing patients for the development of early-onset osteoarthritis. There are many restoration procedures available to treat these injuries, such as bone marrow-stimulation techniques, osteoarticular auto/allograft transplants, and autologous chondrocyte implantation. Each of these techniques has its own limitations, which led researchers to explore new regenerative and repair techniques to produce normal hyaline cartilage. The purpose of this Technical Note is to describe in detail the particulated autologous chondral-platelet-rich plasma matrix implantation (PACI) technique that could be used as a single-stage cartilage restoration procedure for treatment of full-thickness cartilage and osteochondral defects.

A novel autologous-made matrix using hyaline cartilage chips and platelet-rich growth factors for the treatment of full-thickness cartilage or osteochondral defects: Preliminary results

PURPOSE

To report the clinical, functional, and magnetic resonance imaging (MRI)-based outcomes of a novel autologous-made matrix consisting of hyaline cartilage chips combined with mixed plasma poor rich in platelets clot and plasma rich in growth factors (PRGF) for the treatment of knee full-thickness cartilage or osteochondral defects.

METHODS

Between July 2015 and January 2018, all patients with full-thickness cartilage or osteochondral defects undergoing this novel cartilage restoration surgical technique were approached for eligibility. Indications for this procedure included traumatic or atraumatic full-thickness knee cartilage defects or osteochondritis dissecans. Patients were included if they had no concomitant use of stem cells, previous ipsilateral cartilage repair procedure, or follow-up was less than 10 months. The outcomes included data on current symptoms, physical exam, patient-reported, and functional outcomes (visual analogue scale (VAS) for pain, Lysholm score, Tegner activity scale, International Knee Documentation Committee (IKDC) subjective form, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Lequesne index, and short form-12 (SF-12)) and the magnetic resonance observation of cartilage repair tissue (MOCART) score. These outcomes were compared to preoperative values, except for the MOCART score.

RESULTS

Fifteen patients were included in this preliminary study: mean (standard deviation (SD), range) follow-up 15.9 months (7.2, 10-32), age 26.8 years (12.1, 16-58), and body mass index 23.2 (2.1, 19.3-26.9). There were 14 men (93%) and 1 woman (7%). There was a statistically significant improvement between pre- and postoperative periods for VAS for pain (p = 0.003), Lysholm score (p = 0.002), IKDC subjective form (p = 0.003), WOMAC for pain (p = 0.005), WOMAC for stiffness (p = 0.01), WOMAC for function (p = 0.002), Lequesne Index (p = 0.002), and SF-12 physical component summary (p = 0.007). The postoperative mean (SD; range) MOCART score was 70 (12.4; 40-85).

CONCLUSIONS

The use of this novel cartilage restoration surgical technique provides excellent clinical, functional, and MRI-based outcomes in young, active individuals with full-thickness cartilage or osteochondral defects.

LEVEL OF EVIDENCE

Level IV-Therapeutic case series.

Potential problems in the use of patient reported outcome measures (PROMs) and reporting of PROM data in sports science

To use an inadequate patient reported outcome measure (PROM) or use a PROM in an inappropriate way potentially influences the quality of measurement. The objectives of this study were to define potential inadequate uses of PROMs in sports research studies and estimate how often they occur. A consensus group consisting of medical researchers, statisticians, and psychometricians identified and defined potentially irregular applications of PROMs. Occurrence of these in 349 consecutive articles in sports medicine in which PROMs were used as primary outcomes was reviewed. In all, 14 different potential problems were defined, and one or several occurred in 172 of the articles (49%). These were as follows: using a PROM that was developed for a different patient group (100 cases), using two or more PROMs with identical questions (94), aggregation of domain sum scores (82), combinations of subjective and objective measures (27), using a PROM to diagnose or evaluate the individual patient (7), using a PROM for a single limb (3), recall bias (3), exclusion of domains or items (3), construction of a PROM for a specific occasion (2), categorization of the scale (2), and mixing different versions of a PROM (1). Adaption of scale scores (e. g., to percentage) when results are reported (144) carries a risk of miscalculation and distorted impression of results. Data related to uncertainty about completing the PROM and the handling of missing data were not provided in the manuscripts. In conclusion, potential problems in the use and reporting of PROMs are common in sports research, and this can influence the validity of reported results.

Efficacy of one-stage cartilage repair using allogeneic mesenchymal stromal cells and autologous chondron transplantation (IMPACT) compared to nonsurgical treatment for focal articular cartilage lesions of the knee: study protocol for a crossover randomized controlled trial

BACKGROUND

Articular cartilage defects in the knee have poor intrinsic healing capacity and may lead to functional disability and osteoarthritis (OA). "Instant MSC Product accompanying Autologous Chondron Transplantation" (IMPACT) combines rapidly isolated recycled autologous chondrons with allogeneic MSCs in a one-stage surgery. IMPACT was successfully executed in a first-in-man investigator-driven phase I/II clinical trial in 35 patients. The purpose of this study is to compare the efficacy of IMPACT to nonsurgical treatment for the treatment of large (2-8 cm2) articular cartilage defects in the knee.

METHODS

Sixty patients will be randomized to receive nonsurgical care or IMPACT. After 9 months of nonsurgical care, patients in the control group are allowed to receive IMPACT surgery. The Knee Injury and Osteoarthritis Outcome Score (KOOS), pain (numeric rating scale, NRS), and EuroQol five dimensions five levels (EQ5D-5 L) will be used to compare outcomes at baseline and 3, 6, 9, 12, and 18 months after inclusion. Cartilage formation will be assessed at baseline, and 6 and 18 months after inclusion using MRI. An independent rheumatologist will monitor the onset of a potential inflammatory response. (Severe) adverse events will be recorded. Lastly, the difference between IMPACT and nonsurgical care in terms of societal costs will be assessed by monitoring healthcare resource use and productivity losses during the study period. A health economic model will be developed to estimate the incremental cost-effectiveness ratio of IMPACT vs. nonsurgical treatment in terms of costs per quality adjusted life year over a 5-year time horizon.

DISCUSSION

This study is designed to evaluate the efficacy of IMPACT compared to nonsurgical care. Additionally, safety of IMPACT will be assessed in 30 to 60 patients. Lastly, this study will evaluate the cost-effectiveness of IMPACT compared to nonsurgical care.

TRIAL REGISTRATION

NL67161.000.18 [Registry ID: CCMO] 2018#003470#27 [EU-CTR; registered on 26 March 2019] NCT04236739 [ ClinicalTrials.gov ] [registered after start of inclusion; 22 January 2020].

Advances and prospects in biomimetic multilayered scaffolds for articular cartilage regeneration

Due to the sophisticated hierarchical structure and limited reparability of articular cartilage (AC), the ideal regeneration of AC defects has been a major challenge in the field of regenerative medicine. As defects progress, they often extend from the cartilage layer to the subchondral bone and ultimately lead to osteoarthritis. Tissue engineering techniques bring new hope for AC regeneration. To meet the regenerative requirements of the heterogeneous and layered structure of native AC tissue, a substantial number of multilayered biomimetic scaffolds have been studied. Ideal multilayered scaffolds should generate zone-specific functional tissue similar to native AC tissue. This review focuses on the current status of multilayered scaffolds developed for AC defect repair, including design strategies based on the degree of defect severity and the zone-specific characteristics of AC tissue, the selection and composition of biomaterials, and techniques for design and manufacturing. The challenges and future perspectives of biomimetic multilayered scaffold strategies for AC regeneration are also discussed.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Repair of large condylar osteochondral defects of the knee by collagen scaffold. Minimum two-year outcomes

INTRODUCTION

Collagen scaffolds are a good surgical option for covering large focal osteochondral defects in the knee. In the recent literature there is a wide range of patient profiles and chondral defect treatments (chondral and osteochondral defects, associated procedures, etc.). The aim of the present study was to evaluate clinical and imaging outcomes with collagen scaffolds and to assess any correlation between medium-term clinical outcome and MRI features. The hypothesis was that there is no correlation between clinical outcome and MRI after 2 years postoperatively.

MATERIAL AND METHODS

A single-center retrospective observational study included all patients receiving a MaioRegen® scaffold for large painful focal osteochondral defect of the femoral condyle. There were 17 patients, with a mean age of 28±9 years. Defect locations comprised 12 medial femoral condyles, 4 lateral femoral condyles and 1 lateral tibial plateau. Mean defect area was 4.5±1.4cm². All patients were evaluated clinically and on KOOS and objective and subjective IKDC scales, with MRI at last follow-up.

RESULTS

At a mean follow-up of 46±17 months, mean subjective IKDC was 67.8±23; KOOS scores were: symptoms, 78±22; pain, 78±23; function, 85±20; sports, 66±27; and activities of daily living, 59±25. MRI MOCART score revealed incomplete scaffold healing in 21.4% of cases, with variable signal intensity within regenerated tissue. Functional scores did not correlate with reconstruction aspect on MRI.

DISCUSSION/CONCLUSION

3D collagen scaffolds yield good medium-term clinical outcomes in large osteochondral defects of the knee. There is, however, a discrepancy between MRI features of the recipient site and objective and subjective clinical scores. These scaffolds may be a good option for treating large focal osteochondral defects in knees of young patients, but MRI does not provide satisfactory medium-term assessment.

Combination of Filtered Bone Marrow Aspirate and Biomimetic Scaffold for the Treatment of Knee Osteochondral Lesions: Cellular and Early Clinical Results of a Single Centre Case Series

BACKGROUND

Osteochondral injury is a very common orthopaedic pathology, mainly affecting young, active population, with limited current treatment options. Herein we are presenting cellular and early clinical data of a patient series treated for chronic osteochondral lesions in the knee with a filter-based intra-operative bone marrow aspirate (BMA) separation device.

METHODS

Fifteen patients with chronic knee osteochondral lesions (60% females, 19-59 years) were included in this prospective case series. Filtered BMA (f-BMA), containing mesenchymal stem/stromal cells (MSCs), was combined with a biomimetic collagen-hydroxyapatite scaffold (CHAS) and implanted into the site of the lesion. Harvested BMA and post-separation f-BMA were analysed for blood cell counts, flow cytometry, and fibroblast colony forming units (CFU-Fs). Patients were followed for serious adverse events and graft failures. Clinical evaluation was assessed using the knee injury and osteoarthritis outcome score (KOOS). In 8 patients a magnetic resonance imaging (MRI)/arthroscopy were performed.

RESULTS

Cell suspension contained 0.027% CD271⁺ CD45^- 7-AAD^- cells, 0.15% CD73⁺ CD90⁺ CD105⁺ cells and 0.0012% CFU-Fs of all nucleated cells with 86% viability. Filtration process resulted in 12.8 (4.0-40.8) fold enrichment in terms of CFU-F content in comparison to initial BMA. No serious adverse events related directly to the osteochondral treatment were reported. After an average follow-up of 20 months (14-25) all KOOS subscales (Symptoms/Pain/Daily activities/Sport and recreation/Quality of life) increased significantly from pre-operative 55/56/67/30/30 to post-operative 73/76/79/51/52 (p values < 0.05), respectively. MRI or arthroscopic evaluation revealed nearly normal to normal overall International Cartilage Repair Society assessment in 7/8 patients.

CONCLUSION

The filter-based BMA separation procedure significantly increased the frequency of mesenchymal stem/stromal cells (MSCs), however their concentration was not increased. The clinical evaluation revealed high safety profile of the treatment and resulted in improved clinical status of the patients.

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.

Cell-Free Osteochondral Scaffold for the Treatment of Focal Articular Cartilage Defects in Early Knee OA: 5 Years' Follow-Up Results

The purpose of this study was to investigate the clinical results at five years' follow-up of a tri-layered nanostructured biomimetic osteochondral scaffold used for focal articular cartilage defects in patients meeting the criteria of early osteoarthritis (EOA). The study population comprised 22 patients (mean age: 39 years), prospectively assessed before surgery, at 24 and 60 months' follow-up. Inclusion criteria were: at least two episodes of knee pain for more than 10 days in the last year, Kellgren-Lawrence OA grade 0, I or II and arthroscopic or MRI findings according to the European Society of Sports Traumatology, Knee Surgery & Arthroscopy (ESSKA) criteria. Clinical results demonstrated significant improvement in International Knee Documentation Committee (IKDC) subjective and objective scores and in Tegner score, although activity level never reached the pre-injury level. The complication rate of this study was 8.3%. Two patients underwent re-operation (8.3%), while a comprehensive definition of failure (including both surgical and clinical criteria) identified four failed patients (16.6%) at this mid-term follow-up evaluation. The use of a free-cell osteochondral scaffold represented a safe and valid alternative for the treatment of focal articular cartilage defects in the setting of an EOA, and was able to permit a significant clinical improvement and stable outcome with low complication and failure rates.

Cell-Free Biomimetic Osteochondral Scaffold: Implantation Technique

This 1-stage cell-free scaffold-based technique is indicated for the treatment of full-thickness chondral and osteochondral lesions in the knee, regardless of the lesion size. The aim of the procedure is restoration of the osteochondral unit while avoiding the issues of donor site morbidity and those related to cell management.

Description

The surgical technique is simple and can be performed as a 1-stage procedure. The lesion site is visualized through a standard knee medial or lateral parapatellar arthrotomy. The defect is prepared by excision of the injured cartilage and subchondral bone to ensure adequate bone-marrow blood flow and to create a squared, regularly shaped lodging for the device. The scaffold is then shaped and sized according to the dimensions of the prepared lesion site and implanted by press-fitting or with addition of fibrin glue. Finally, the complete range of motion is tested to assess the stability of the implant before and after releasing the tourniquet.

Alternatives

Nonsurgical alternatives have been reported to include nonpharmacological modalities, such as dietary supplements, and pharmacological therapies as well as physical therapies and novel biological procedures involving injections of various substances¹. There are several surgical alternatives, including among others microfracture, mosaicplasty, osteochondral allograft, and total knee arthroplasty, depending primarily on the disease stage and etiology as well as the specific patient conditions^2,3.

Rationale

This cell-free device is engineered in 3 layers to mimic the structure and composition of the osteochondral unit in order to guide resident cells toward an ordered regeneration of both bone and cartilage layers, providing a better quality of regenerated articular surface. The treatment approach offers a useful alternative to current procedures in the field of osteochondral lesions, in particular for young and middle-aged patients affected by symptomatic defects in which subchondral bone is likely involved. The advantages of this scaffold include the ability to perform a 1-stage surgical procedure, off-the-shelf availability, a straightforward surgical technique, and lower costs compared with cell-based regenerative options. Furthermore, in contrast to some more traditional treatments, it can be used for large lesions.

Treatment of unstable knee osteochondritis dissecans in the young adult: results and limitations of surgical strategies-The advantages of allografts to address an osteochondral challenge

Joint surface incongruence resulting from osteochondritis dissecans (OCD) alters the articular physiologic congruence, increasing the contact stress on adjacent joint surfaces and accelerating wear and the cascade of joint degeneration. Accordingly, the restoration of articular surface integrity is of major importance, especially in young adults where, in lesions left untreated or following simple fragment excision, early osteoarthritis can be anticipated. Therefore, the treatment algorithm in unstable knee OCD of the young adult foresees surgical options to restore the articular surface. Several procedures have been proposed, including refixation of the detached fragment bone marrow stimulation, osteochondral autograft implantation, fresh osteochondral allograft transplantation, and cell-based or cell-free regenerative techniques. The aim of this review was to summarize the evidence for these surgical strategies, reporting their results and limitations. The overall evidence documents positive results for each of the assorted surgical procedures applied to treat unstable OCD, thus indicating support for their selected use to treat osteochondral defects paying particular attention to their specific indications for the lesion characteristics. The fixation of a good quality fragment should be pursued as a first option, while unfixable small lesions may benefit from autografts. For large lesions, available cell-based or cell-free osteochondral scaffold are a feasible solution but with limitation in terms of regenerated tissue quality. In this light, fresh allografts may offer articular surface restoration with viable physiologic osteochondral tissue providing a predictably successful outcome, and therefore they may currently represent the most suitable option to treat unstable irreparable OCD lesion in young adults. LEVEL OF EVIDENCE: V.

Articular cartilage regeneration and tissue engineering models: a systematic review

INTRODUCTION

Cartilage regeneration and restoration is a major topic in orthopedic research as cartilaginous degeneration and damage is associated with osteoarthritis and joint destruction. This systematic review aims to summarize current research strategies in cartilage regeneration research.

MATERIALS AND METHODS

A Pubmed search for models investigating single-site cartilage defects as well as chondrogenesis was conducted and articles were evaluated for content by title and abstract. Finally, only manuscripts were included, which report new models or approaches of cartilage regeneration.

RESULTS

The search resulted in 2217 studies, 200 of which were eligible for inclusion in this review. The identified manuscripts consisted of a large spectrum of research approaches spanning from cell culture to tissue engineering and transplantation as well as sophisticated computational modeling.

CONCLUSIONS

In the past three decades, knowledge about articular cartilage and its defects has multiplied in clinical and experimental settings and the respective body of research literature has grown significantly. However, current strategies for articular cartilage repair have not yet succeeded to replicate the structure and function of innate articular cartilage, which makes it even more important to understand the current strategies and their impact. Therefore, the purpose of this review was to globally summarize experimental strategies investigating cartilage regeneration in vitro as well as in vivo. This will allow for better referencing when designing new models or strategies and potentially improve research translation from bench to bedside.

Neither significant osteoarthritic changes nor deteriorating subjective outcomes occur after hybrid fixation of osteochondritis dissecans in the young adult

PURPOSE

The goal of the fixation of painful osteochondritis dissecans of the femoral condyles in adults is to integrate the osteochondral fragment and thus achieve a normal hyaline cartilaginous coverage. The addition of a biological process to primary fixation may result in improved fragment integration (hybrid fixation). Osteochondral plugs may fulfil this role. The aim of this study was to evaluate long-term clinical and radiological results after hybrid fixation of unstable osteochondritis dissecans. The hypothesis was that the rate of secondary osteoarthritis would be low.

METHODS

Nine patients treated by hybrid fixation were retrospectively reviewed at a median follow-up of 10.1 years (range 7-14). The median age at surgery was 21 (range 17-28). Six of them were evaluated as ICRS grade II and three, as ICRS grade III. The mean surface of the lesion was 4.5 cm². All patients were followed up clinically (IKDC, KOOS, Lysholm) and radiologically [Kellgren-Lawrence score (KL)].

RESULTS

During arthroscopic assessment at the time of screw removal (3 months after surgery), the fragments were stable, and autograft plugs were all well integrated. At the most recent follow-up visit, the median IKDC score was 85.8 (range 51.72-100), the KOOS score was 87.7 (52.4-100), and the Lysholm scale score was 89.8 (77-100). In 7 out of 9 patients, radiographs showed a joint space KL grade of 0 or 1.

CONCLUSION

Hybrid fixation for treating osteochondritis dissecans lesions of the femoral condyles using mechanical and biological fixation provides healing of the osteochondral fragments with good long-term outcomes. No significant osteoarthritic change was seen with this technique at a mid-term follow-up.

LEVEL OF EVIDENCE

IV-case series.

Use of a Biomimetic Scaffold for the Treatment of Osteochondral Lesions in Early Osteoarthritis

The aim of this study is to investigate clinical and radiographic outcomes of a biomimetic scaffold for the treatment of osteochondral knee lesions in patients with early OA. Study population was represented by 26 patients with a mean age of 44 years affected by early OA. Inclusion criteria were two episodes of knee pain for more than 10 days in the last year, Kellgren-Lawrence OA grade 0 or I or II, and arthroscopic findings of cartilage defects. Nineteen patients had a previous surgery, 11 of which were revision surgeries of osteochondral unit. All patients were treated with a biomimetic scaffold with a tri-layered structure of type I equine collagen and magnesium-enriched hydroxyapatite. Clinical outcomes were evaluated using the IKDC, Lysholm, VAS, KOOS, and Tegner scores at baseline and at an average follow-up of 35 months. Magnetic resonance imaging (MRI) was performed at follow-up time in 19 patients. Clinical outcomes showed significant improvement in VAS, Lysholm, IKDC subjective score, and KOOS subscales in 69% of the patients. Complication rate of this cases series was 11%, with no surgical failure, although 31% of patients did not reach a significant improvement and were thus considered as clinical failure. MRI analysis showed integration of the scaffold only in 47% of the patients, with partial regeneration of the subchondral bone. No correlation between clinics and radiological images was found. The use of a biomimetic osteochondral scaffold in the setting of an early OA, alone or associated with other procedures, appeared to be a valid and safe option, able to provide good and stable clinical outcomes with high patient's satisfaction and low complication rate.

Implant strategy affects scaffold stability and integrity in cartilage treatment

PURPOSE

To identify the most appropriate implantation strategy for a novel chondral scaffold in a model simulating the early post-operative phase, in order to optimize the implant procedure and reduce the risk of early failure.

METHODS

Eight human cadaveric limbs were strapped to a continuous passive motion device and exposed to extension-flexion cycles (0°-90°). Chondral lesions (1.8 cm diameter) were prepared on condyles, patella and trochlea for the implant of a bi-layer collagen-hydroxyapatite scaffold. The first set-up compared four fixation techniques: press-fit (PF) vs. fibrin glue (FG) vs. pins vs. sutures; the second compared circular and square implants; the third investigated stability in a weight-bearing simulation. The scaffolds were evaluated using semi-quantitative Drobnic and modified Bekkers scores.

RESULTS

FG presented higher total Drobnic and Bekkers scores compared to PF (both p = 0.002), pins (p = 0.013 and 0.001) and sutures (p = 0.001 and < 0.0005). Pins offered better total Drobnic and Bekkers scores than PF in the anterior femoral condyles (p = 0.007 and 0.065), similar to FG. The comparison of round and square implants applied by FG showed worst results for square lesions (Drobnic score p = 0.049, Bekkers score p = 0.037). Finally, load caused worst overall results (Drobnic p = 0.018).

CONCLUSIONS

FG improves the fixation of this collagen-HA scaffold regardless of lesion location, improving implant stability while preserving its integrity. Pins represent a suitable option only for lesions of the anterior condyles. Square scaffolds present weak corners, therefore, round implants should be preferred. Finally, partial weight-bearing simulation significantly affected the scaffold. These findings may be useful to improve surgical technique and post-operative management of patients, to optimize the outcome of chondral scaffold implantation.

Scaffold-Based Therapies: Proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle

BACKGROUND

The evidence supporting best practice guidelines in the field of cartilage repair of the ankle are based on both low quality and low levels of evidence. Therefore, an international consensus group of experts was convened to collaboratively advance toward consensus opinions based on the best available evidence on key topics within cartilage repair of the ankle. The purpose of this article is to report the consensus statements on "Scaffold-Based Therapies" developed at the 2017 International Consensus Meeting on Cartilage Repair of the Ankle.

METHODS

Seventy-five international experts in cartilage repair of the ankle representing 25 countries and 1 territory were convened and participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted within 11 working groups focusing on specific topics within cartilage repair of the ankle, after which a comprehensive literature review was performed and the available evidence for each statement was graded. Discussion and debate occurred in cases where statements were not agreed upon in unanimous fashion within the working groups. A final vote was then held, and the strength of consensus was characterized as follows: consensus, 51% to 74%; strong consensus, 75% to 99%; unanimous, 100%.

RESULTS

A total of 9 statements on scaffold-based therapies reached consensus during the 2017 International Consensus Meeting on Cartilage Repair of the Ankle. One achieved unanimous support, 8 reached strong consensus (greater than 75% agreement), and 1 was removed because of redundancy in the information provided. All statements reached at least 80% agreement.

CONCLUSIONS

This international consensus derived from leaders in the field will assist clinicians with applying scaffold-based therapies as a treatment strategy for osteochondral lesions of the talus.

LEVEL OF EVIDENCE

Level V, expert opinion.

Allograft Cartilage Replacements

The body's ability to repair injured articular cartilage is poor due to the inherent physiology of cartilage. Joint arthritis, whether through injury or increasing age, is a prevalent condition. Treatment of an articular cartilage injury may include arthroplasty, fusion, or repair. A popular pathway of treatment in a salvageable joint is often to avoid donor site morbidity and place increased effort to reestablish native cartilage with the use of allografts. This article discusses current research on acellular and cellular allografts for articular cartilage restoration.

Recent Approaches to the Manufacturing of Biomimetic Multi-Phasic Scaffolds for Osteochondral Regeneration

Cartilage lesions of the knee are common disorders affecting people of all ages; as the lesion progresses, it extends to the underlying subchondral bone and an osteochondral defect appears. Osteochondral (OC) tissue compromises soft cartilage over hard subchondral bone with a calcified cartilage interface between these two tissues. Osteochondral defects can be caused by numerous factors such as trauma and arthritis. Tissue engineering offers the possibility of a sustainable and effective treatment against osteochondral defects, where the damaged tissue is replaced with a long-lasting bio-manufactured replacement tissue. This review evaluates both bi-phasic and multi-phasic scaffold-based approaches of osteochondral tissue regeneration, highlighting the importance of having an interface layer between the bone and cartilage layer. The significance of a biomimetic approach is also evidenced and shown to be more effective than the more homogenous design approach to osteochondral scaffold design. Recent scaffold materials and manufacturing techniques are reviewed as well as the current clinical progress with osteochondral regeneration scaffolds.

Osteochondral tissue repair in osteoarthritic joints: clinical challenges and opportunities in tissue engineering

Osteoarthritis (OA), identified as one of the priorities for the Bone and Joint Decade, is one of the most prevalent joint diseases, which causes pain and disability of joints in the adult population. Secondary OA usually stems from repetitive overloading to the osteochondral (OC) unit, which could result in cartilage damage and changes in the subchondral bone, leading to mechanical instability of the joint and loss of joint function. Tissue engineering approaches have emerged for the repair of cartilage defects and damages to the subchondral bone in the early stages of OA and have shown potential in restoring the joint’s function. In this approach, the use of three-dimensional scaffolds (with or without cells) provides support for tissue growth. Commercially available OC scaffolds have been studied in OA patients for repair and regeneration of OC defects. However, none of these scaffolds has shown satisfactory clinical results. This article reviews the OC tissue structure and the design, manufacturing and performance of current OC scaffolds in treatment of OA. The findings demonstrate the importance of biological and biomechanical fixations of OC scaffolds to the host tissue in achieving an improved cartilage fill and a hyaline-like tissue formation. Achieving a strong and stable subchondral bone support that helps the regeneration of overlying cartilage seems to be still a grand challenge for the early treatment of OA.

Enhancing Biological and Biomechanical Fixation of Osteochondral Scaffold: A Grand Challenge

Osteoarthritis (OA) is a degenerative joint disease, typified by degradation of cartilage and changes in the subchondral bone, resulting in pain, stiffness and reduced mobility. Current surgical treatments often fail to regenerate hyaline cartilage and result in the formation of fibrocartilage. Tissue engineering approaches have emerged for the repair of cartilage defects and damages to the subchondral bones in the early stage of OA and have shown potential in restoring the joint's function. In this approach, the use of three-dimensional scaffolds (with or without cells) provides support for tissue growth. Commercially available osteochondral (OC) scaffolds have been studied in OA patients for repair and regeneration of OC defects. However, some controversial results are often reported from both clinical trials and animal studies. The objective of this chapter is to report the scaffolds clinical requirements and performance of the currently available OC scaffolds that have been investigated both in animal studies and in clinical trials. The findings have demonstrated the importance of biological and biomechanical fixation of the OC scaffolds in achieving good cartilage fill and improved hyaline cartilage formation. It is concluded that improving cartilage fill, enhancing its integration with host tissues and achieving a strong and stable subchondral bone support for overlying cartilage are still grand challenges for the early treatment of OA.

Good clinical results but moderate osseointegration and defect filling of a cell-free multi-layered nano-composite scaffold for treatment of osteochondral lesions of the knee

PURPOSE

The aim of this retrospective study was to evaluate the clinical and radiological results of a nano-composite multi-layered three-dimensional biomaterial scaffold for treatment of osteochondral lesions (OCL) of the knee. It was a particular radiological interest to analyse the osseointegration, filling of the defects and the bone tracer uptake (BTU), and it was hypothesised that this scaffold, which was created to mimic the entire osteo-cartilaginous unit, is integrated within the bone 12 months postoperatively and comes along with improved patients symptoms and function.

METHODS

Fourteen patients (male:female = 11:3, mean age ± SD 33.1 ± 10.7 years) treated for OCL (size 1.0-3.5 cm²) were clinically and radiologically evaluated at 1 year postoperatively. The data were prospectively collected including SPECT/CT, Tegner and Lysholm scores. BTU was anatomically localised and volumetrically quantified in SPECT/CT. Defect filling was analysed in CT. Spearman's rho and Wilcoxon test were used for correlation of BTU in SPECT/CT and clinical scores (p < 0.05).

RESULTS

A significant improvement in Lysholm knee score (p < 0.001) and slight deterioration in Tegner score were found (p < 0.01). A complete filling of the defect was shown in 14%, a partial filling in 14% and only minor filling was seen in 72%. A significant correlation (p < 0.001) was found between location of osteochondral lesions and increased BTU. At the lesion sites pre- and postoperative BTU was markedly increased and did not show any decrease at 12-month follow-up. Median Tegner and mean Lysholm scores did not correlate with BTU at any time.

CONCLUSIONS

Treatment of OCL in the knee joint with a nano-composite multi-layered three-dimensional biomaterial scaffold resulted in a significant clinical improvement at 1-year follow-up. However, osseointegration was still ongoing at 12-month follow-up.

LEVEL OF EVIDENCE

Case series, Level IV.