Autologous chondrocyte implantation and osteochondral cylinder transplantation in cartilage repair of the knee joint. A prospective, comparative trial

Autologous Osteochondral Transfer of the Knee Demonstrates Continued High Rates of Return to Sport and Low Rates of Conversion to Arthroplasty at Long-Term Follow-Up: A Systematic Review

PURPOSE

To perform a systematic review of the literature to evaluate (1) activity level and knee function, (2) reoperation and failure rates, and (3) risk factors for reoperation and failure of autologous osteochondral transfer (AOT) at long-term follow-up.

METHODS

A comprehensive review of the long-term outcomes of AOT was performed. Studies reported on activity-based outcomes (Tegner Activity Scale) and clinical outcomes (Lysholm score and International Knee Documentation Committee score). Reoperation and failure rates as defined by the publishing authors were recorded for each study. Modified Coleman Methodology Scores were calculated to assess study methodological quality.

RESULTS

Twelve studies with a total of 495 patients and an average age of 32.5 years at the time of surgery and a mean follow-up of 15.1 years (range, 10.4-18.0 years) were included. The mean defect size was 3.2 cm2 (range, 1.9-6.9 cm2). The mean duration of symptoms before surgery was 5.1 years. Return to sport rates ranged from 86% to 100%. Conversion to arthroplasty rates ranged from 0% to 16%. The average preoperative International Knee Documentation Committee scores ranged from 32.9 to 36.8, and the average postoperative International Knee Documentation Committee scores at final follow-up ranged from 66.3 to 77.3. The average preoperative Lysholm scores ranged from 44.5 to 56.0 and the average postoperative Lysholm scores ranged from 70.0 to 96.5. The average preoperative Tegner scores ranged from 2.5 to 3.0, and the average postoperative scores ranged from 4.1 to 7.0.

CONCLUSIONS

AOT of the knee resulted in high rates of return to sport with correspondingly low rates of conversion to arthroplasty at long-term follow-up. In addition, AOT demonstrated significant improvements in long-term patient-reported outcomes from baseline.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

A Finite Element Model to Investigate the Stability of Osteochondral Grafts Within a Human Tibiofemoral Joint

Osteochondral grafting has demonstrated positive outcomes for treating articular cartilage defects by replacing the damaged region with a cylindrical graft consisting of bone with a layer of cartilage. However, factors that cause graft subsidence are not well understood. The aim of this study was to develop finite element (FE) models of osteochondral grafts within a tibiofemoral joint, suitable for an investigation of parameters affecting graft stability. Cadaveric femurs were used to experimentally calibrate the bone properties and graft-bone frictional forces for use in corresponding image-based FE models, generated from µCT scan data. Effects of cartilage defects and osteochondral graft repair were measured by examining contact pressure changes using further in vitro tests. Here, six defects were created in the femoral condyles, which were subsequently treated with osteochondral autografts or metal pins. Matching image-based FE models were created, and the contact patches were compared. The bone material properties and graft-bone frictional forces were successfully calibrated from the initial tests with good resulting levels of agreement (CCC = 0.87). The tibiofemoral joint experiment provided a range of cases that were accurately described in the resultant pressure maps and were well represented in the FE models. Cartilage defects and repair quality were experimentally measurable with good agreement in the FE model pressure maps. Model confidence was built through extensive validation and sensitivity testing. It was found that specimen-specific properties were required to accurately represent graft behaviour. The final models produced are suitable for a range of parametric testing to investigate immediate graft stability.

Bioactive decellularized extracellular matrix-based hydrogel supports human adipose tissue-derived stem cell maintenance and fibrocartilage phenotype

Articular cartilage is a highly specialized tissue able to tolerate physical stress. However, its capacity for restoration is restricted, and injuries to the cartilage do not recover spontaneously. Interest in mesenchymal stem cells derived from human adipose tissue (hASCs) is growing due to their potential to improve tissue healing and recovery. Decellularized extracellular matrix (dECM)-based hydrogels combined with hASCs could serve as an interface for studying behavior and differentiation properties in a cartilage microenvironment. In the present study, we described the behavior of hASCs cultured in a commercial dECM MatriXpec™. The structural microtopography of MatriXpec™ was analyzed by scanning electron micrography, and its protein composition was accessed by mass spectrometry. The protein composition of MatriXpec™ is mainly represented by collagen proteins, building its fibrous ultrastructure. hASCs were cultured three-dimensionally (3D) on MatriXpec™ to perform cell viability, growth, and cartilage differentiation analysis. We showed that MatriXpec™ could be loaded with hASCs and that it supports cell maintenance for several days. We observed that the three-dimensional ultrastructure of the biomaterial is composed of nanofibers, and its protein composition reflects the tissue from which it was harvested. Finally, we showed that the molecular cues from the hydrogel are biologically active as these influence cell behavior and differentiation phenotype, increasing the expression of fibrocartilage-related genes such as SOX9, COL1, COL10, and MMP13. MatriXpec™ hydrogel can be used as an interface for 3D hASCs culture studies as it maintains cell viability and supports its differentiation process.

Cartilage thickness mismatches in patellar osteochondral allograft transplants affect local cartilage stresses

Osteochondral allograft implantation is a form of cartilage transplant in which a cylindrical graft of cartilage and subchondral bone from a donor is implanted into a patient's prepared articular defect site. No standard exists for matching the cartilage thickness of the donor and recipient. The goal of this study was to use finite element (FE) analysis to identify the effect of cartilage thickness mismatches between donor and recipient cartilage on cartilage stresses in patellar transplants. Two types of FE models were used: patient-specific 3D models and simplified 2D models. 3D models highlighted which geometric features produced high-stress regions in the patellar cartilage and provided ranges for the parameter sweeps that were conducted with 2D models. 2D models revealed that larger thickness mismatches, thicker recipient cartilage, and a donor-to-recipient cartilage thickness ratio (DRCR) < 1 led to higher stresses at the interface between the donor and recipient cartilage. A surface angle between the donor-recipient cartilage interface and cartilage surface normal near the graft boundary increased stresses when DRCR > 1, with the largest increase observed for an angle of 15°. A surface angle decreased stresses when DRCR < 1. Clinical Significance: This study highlights a potential mechanism to explain the high rates of failure of patellar OCAs. Additionally, the relationship between geometric features and stresses explored in this study led to a hypothetical scoring system that indicates which transplanted patellar grafts may have a higher risk of failure.

Injectable hydrogels: An emerging therapeutic strategy for cartilage regeneration

The impairment of articular cartilage due to traumatic incidents or osteoarthritis has posed significant challenges for healthcare practitioners, researchers, and individuals suffering from these conditions. Due to the absence of an approved treatment strategy for the complete restoration of cartilage defects to their native state, the tissue condition often deteriorates over time, leading to osteoarthritic (OA). However, recent advancements in the field of regenerative medicine have unveiled promising prospects through the utilization of injectable hydrogels. This versatile class of biomaterials, characterized by their ability to emulate the characteristics of native articular cartilage, offers the distinct advantage of minimally invasive administration directly to the site of damage. These hydrogels can also serve as ideal delivery vehicles for a diverse range of bioactive agents, including growth factors, anti-inflammatory drugs, steroids, and cells. The controlled release of such biologically active molecules from hydrogel scaffolds can accelerate cartilage healing, stimulate chondrogenesis, and modulate the inflammatory microenvironment to halt osteoarthritic progression. The present review aims to describe the methods used to design injectable hydrogels, expound upon their applications as delivery vehicles of biologically active molecules, and provide an update on recent advances in leveraging these delivery systems to foster articular cartilage regeneration.

Quantitative T2 mapping monitoring the maturation of engineered elastic cartilage in a rabbit model

BACKGROUND

Cartilage tissue engineering provides a promising approach to reconstruct craniofacial defects, and a noninvasive method is needed to assess its effectiveness. Although magnetic resonance imaging (MRI) has been used to evaluate articular cartilage in vivo, few studies focused on its feasibility in monitoring engineered elastic cartilage (EC).

METHODS

Auricular cartilage, silk fibroin (SF) scaffold, and EC consisting of rabbit auricular chondrocytes and SF scaffold were transplanted subcutaneously into the rabbit back. In eight weeks after transplantation, grafts were imaged by MRI using PROSET, PDW VISTA SPAIR, 3D T2 VISTA, 2D MIXED T2 Multislice, and SAG TE multiecho sequences, followed by histological examination and biochemical analysis. Statistical analyses were performed to identify the association between T2 values and biochemical indicator values of EC.

RESULTS

In vivo imaging shows that 2D MIXED T2 Multislice sequence (T2 mapping) clearly distinguished the native cartilage, engineered cartilage and fibrous tissue. T2 values showed high correlations with cartilage-specific biochemical parameters at different time points, especially the elastic cartilage specific protein elastin (ELN, r= -0.939, P < 0.001).

CONCLUSION

Quantitative T2 mapping can effectively detect the in vivo maturity of engineered elastic cartilage after subcutaneously transplantation. This study would promote the clinical application of MRI T2 mapping in monitoring engineered elastic cartilage in the repair of craniofacial defects.

Isolated Osteochondral Autograft Versus Allograft Transplantation for the Treatment of Symptomatic Cartilage Lesions of the Knee: A Systematic Review and Meta-analysis

BACKGROUND

Focal cartilage lesions of the knee remain a difficult entity to treat. Current treatment options include arthroscopic debridement, microfracture, autograft or allograft osteochondral transplantation, and cell-based therapies such as autologous chondrocyte transplantation. Osteochondral transplantation techniques restore the normal topography of the condyles and provide mature hyaline cartilage in a single-stage procedure. However, clinical outcomes comparing autograft versus allograft techniques are scarce.

PURPOSE

To perform a comprehensive systematic review and meta-analysis of high-quality studies to evaluate the results of osteochondral autograft and allograft transplantation for the treatment of symptomatic cartilage defects of the knee.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 2.

METHODS

A comprehensive search of the literature was conducted using various databases. Inclusion criteria were level 1 or 2 original studies, studies with patients reporting knee cartilage injuries and chondral defects, mean follow-up ≥2 years, and studies focusing on osteochondral transplant techniques. Exclusion criteria were studies with nonknee chondral defects, studies reporting clinical outcomes of osteochondral autograft or allograft combined with other procedures, animal studies, cadaveric studies, non-English language studies, case reports, and reviews or editorials. Primary outcomes included patient-reported outcomes and failure rates associated with both techniques, and factors such as lesion size, age, sex, and the number of plugs transplanted were assessed. Metaregression using a mixed-effects model was utilized for meta-analyses.

RESULTS

The search resulted in 20 included studies with 364 cases of osteochondral autograft and 272 cases of osteochondral allograft. Mean postoperative survival was 88.2% in the osteochondral autograft cohort as compared with 87.2% in the osteochondral allograft cohort at 5.4 and 5.2 years, respectively (P = .6605). Patient-reported outcomes improved by an average of 65.1% and 81.1% after osteochondral autograft and allograft, respectively (P = .0001). However, meta-analysis revealed no significant difference in patient-reported outcome percentage change between osteochondral autograft and allograft (P = .97) and a coefficient of 0.033 (95% CI, -1.91 to 1.98). Meta-analysis of the relative risk of graft failure after osteochondral autograft versus allograft showed no significant differences (P = .66) and a coefficient of 0.114 (95% CI, -0.46 to 0.69). Furthermore, the regression did not find other predictors (mean age, percentage of female patients, lesion size, number of plugs/grafts used, and treatment location) that may have significantly affected patient-reported outcome percentage change or postoperative failure between osteochondral autograft versus allograft.

CONCLUSION

Osteochondral autograft and allograft result in favorable patient-reported outcomes and graft survival rates at medium-term follow-up. While predictors for outcomes such as mean age, percentage of female patients, lesion size, number of plugs/grafts used, and treatment location did not affect the comparison of the 2 cohorts, proper patient selection for either procedure remains paramount to the success and potentially long-term viability of the graft.

Thermosensitive and biodegradable PCL-based hydrogels: potential scaffolds for cartilage tissue engineering

Due to a lack of sufficient blood supply and unique physicochemical properties, the treatment of injured cartilage is laborious and needs an efficient strategy. Unfortunately, most of the current therapeutic approaches are, but not completely, unable to restore the function of injured cartilage. Tissue engineering-based modalities are an alternative option to reconstruct the injured tissue. Considering the unique structure and consistency of cartilage tissue (osteochondral junction), it is mandatory to apply distinct biomaterials with unique properties slightly different from scaffolds used for soft tissues. PCL is extensively used for the fabrication of fine therapeutic scaffolds to accelerate the restorative process. Thermosensitive PCL hydrogels with distinct chemical compositions have paved the way for sophisticated cartilage regeneration. This review aimed to collect recent findings regarding the application of PCL in hydrogels blended with natural, synthetic materials in the context of cartilage healing.

A case report of an adult with bilateral osteochondritis dissecans of the femoral condyles in both knees

INTRODUCTION

There are several possible treatment options for the treatment of focal cartilage defects in the knee. Determining the appropriate treatment option to compensate for an osteochondral defect caused by osteochondritis dissecans (OCD) in adults is difficult. This study was conducted to clarify the importance of Autogenous Osteochondral Grafting by a mosaicplasty method in treating OCD, relieving pain, and improving knee function.

CASE REPORT

Our study is a case report of a young female patient with osteochondritis dissecans in both the medial and lateral femoral condyles of both knees. Three of these were treated with autogenous osteochondral grafting using a mosaicplasty method. The case was done in 2016 and followed up for 5 years, where the functional results were evaluated according to International Knee Documentation Committee (IKDC Questionnaire) and the pain was assessed on a visual analogue scale (VAS).

DISCUSSION

There were no complications associated with surgery. We observed improvement in knee function according to the IKDC questionnaire from 38 before surgery to 85 after a year of surgery and her pain decreased significantly according to the visual analogue scale (VAS) from 7 before surgery to 1 after a year of surgery and continued until the end of the follow-up period.

CONCLUSION

Autologous osteochondral grafting with the mosaicplasty method is a good treatment option to treat osteochondritis dissecans (OCD) in the knee, as it helps to relieve pain and improve the functional state of the knee.

Comparative efficacy of osteochondral autologous transplantation and microfracture in the knee: an updated meta-analysis of randomized controlled trials

INTRODUCTION

More than 19% of patients undergoing knee arthroscopies suffers from articular cartilage defects. The chondral or osteochondral lesion has negative impacts on the knee joints function and the life quality of patients. However, the treatment remains challenging as hyaline cartilage is not renewable. The purpose of this study was to systematically analyze the data of randomized controlled trials for comparing the postoperative outcomes between osteochondral autologous transplantation (OAT) and microfracture (MF) procedure. We hypothesized that the outcomes were better in OAT than MF procedure.

MATERIALS AND METHODS

A systematic literature search of the EMBASE, Pubmed, and Cochrane Library databases was conducted based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The outcome measures include: the rate of excellent or good results, the rate of return to sports, the failure rate, osteoarthritis rate, International Cartilage Repair Society (ICRS) score, Lysholm Knee Score, and Tegner scale. The statistical analysis was completed using Review Manager (RevMan, version 5.3) software.

RESULTS

The systematic search identified 7 studies with a total of 346 patients. The pooled result showed significant differences between the two groups in the rate of return to sports and failure. The following outcome scores showed significant improvement (pre- vs postoperatively): Lysholm score (p = 0.02), Tegner scale (p < 0.00001), and ICRS score (p < 0.00001). The differences were not significant in the excellent or good results and the rate of osteoarthritis.

CONCLUSION

The patients in OAT group may return to play quicker, even return to pre-injury level of activity compared to the MF group. OAT is better than MF procedure in accordance with Lysholm score, Tegner score, ICRS score, and the rate of failure. However, few studies have reported long-term outcomes and there has no uniform criteria for safe return to sports. Further research is needed.

LEVEL OF EVIDENCE

Level II, meta-analysis of randomized controlled trials.

Prognostic factors for the management of chondral defects of the knee and ankle joint: a systematic review

Purpose

Different surgical techniques to manage cartilage defects are available, including microfracture (MFx), autologous chondrocyte implantation (ACI), osteoarticular auto- or allograft transplantation (OAT), autologous matrix-induced chondrogenesis (AMIC). This study investigated the patient-related prognostic factors on the clinical outcomes of surgically treated knee and ankle cartilage defects.

Methods

This study followed the PRISMA statement. In May 2022, the following databases were accessed: PubMed, Google Scholar, Embase, and Scopus. All the studies investigating the outcomes of surgical management for knee and/or talus chondral defects were accessed. Only studies performing mesenchymal stem cells transplantation, OAT, MFx, ACI, and AMIC were considered. A multiple linear model regression analysis through the Pearson Product–Moment Correlation Coefficient was used.

Results

Data from 184 articles (8905 procedures) were retrieved. Female sex showed a positive moderate association with visual analogue scale at last follow-up (P = 0.02). Patient age had a negative association with the American Orthopaedic Foot and Ankle Score (P = 0.04) and Lysholm Knee Scoring Scale (P = 0.03). BMI was strongly associated with graft hypertrophy (P = 0.01). Greater values of VAS at baseline negatively correlate with lower values of Tegner Activity Scale at last follow-up (P < 0.0001).

Conclusion

The clinical outcomes were mostly related to the patients’ performance status prior surgery. A greater BMI was associated with greater rate of hypertrophy. Female sex and older age evidenced fair influence, while symptom duration prior to the surgical intervention and cartilage defect size evidenced no association with the surgical outcome. Lesion size and symptom duration did not evidence any association with the surgical outcome.

Return to Play Criteria Following Surgical Management of Osteochondral Defects of the Knee: A Systematic Review

OBJECTIVE

The objective of this study was to identify and describe the existing literature on criteria used for return to play (RTP) following surgical management of osteochondral defects of the knee.

DESIGN

A systematic review was performed to evaluate the surgical management of osteochondral defects of the knee in skeletally mature patients with a minimum of 2-year follow-up using Level I to IV studies in PubMed EMBASE from January 1998 to January 2016.

RESULTS

Twelve studies with at least one explicitly stated criterion for RTP were identified from a review of 253 published articles. The majority of included studies were Levels II and IV (33%, respectively). Autologous chondrocyte implantation (ACI) was exclusively evaluated in 33.3% of papers and 16.7% evaluated osteochondral allograft transplantation (OCA). Eight different RTP criteria were used alone or in combination across the reviewed studies and time was the most often utilized criterion (83.3%). Minimum time to RTP ranged from 3 to 18 months.

CONCLUSIONS

This systematic review identifies current criteria used in the available literature to dictate RTP. Time from surgery was the most commonly employed criterion across the reviewed studies. Given the complex biological processes inherent to the healing of cartilaginous defects, further research is needed to design more comprehensive guidelines for RTP that are patient-centered and utilize multiple functional and psychological domains relevant to the process of returning to sport.

Influence of Xenogeneic and Alloplastic Carriers for Bone Augmentation on Human Unrestricted Somatic Stem Cells

Alloplastic and xenogeneic bone grafting materials are frequently used for bone augmentation. The effect of these materials on precursor cells for bone augmentation is yet to be determined. The aim of this study was to ascertain, in vitro, how augmentation materials influence the growth rates and viability of human unrestricted somatic stem cells. The biocompatibility of two xenogeneic and one alloplastic bone graft was tested using human unrestricted somatic stem cells (USSCs). Proliferation, growth, survival and attachment of unrestricted somatic stem cells were monitored after 24 h, 48 h and 7 days. Furthermore, cell shape and morphology were evaluated by SEM. Scaffolds were assessed for their physical properties by Micro-CT imaging. USSCs showed distinct proliferation on the different carriers. Greatest proliferation was observed on the xenogeneic carriers along with improved viability of the cells. Pore sizes of the scaffolds varied significantly, with the xenogeneic materials providing greater pore sizes than the synthetic inorganic material. Unrestricted somatic stem cells in combination with a bovine collagenous bone block seem to be very compatible. A scaffold’s surface morphology, pore size and bioactive characteristics influence the proliferation, attachment and viability of USSCs.

The 50 most-cited clinical articles in cartilage surgery research: a bibliometric analysis

PURPOSE

Articular cartilage lesions remain a challenge for orthopedic surgeons. The identification of the most important articles can help identifying the most influential techniques of the past, the current prevalent focus, and emerging strategies. The aim of this study was to identify milestones and trends in cartilage research.

METHODS

This study is a bibliometric analysis based on published articles. All citation count data included in the "Scopus database" were used to identify eligible studies up to December 2020. The 50 most-cited articles on cartilage surgery were ranked based on the citation count and analyzed regarding citation density and quality (Coleman score and RoB 2.0 tool). A further search was performed to identify the most promising clinical studies among the latest publications on cartilage surgery.

RESULTS

Different kinds of cartilage treatments were investigated in the 50 most-cited clinical articles. Regenerative techniques with chondrocytes were the most reported with a total of 23 articles, followed by microfracture technique in 17 articles and mosaicplasty or osteochondral autograft transplantation (OAT) in 11. Forty-five articles focused on the knee. A higher citation density was found in the most recent articles (p = 0.004). The study of the most promising landmarks of the most recent articles showed new cell-free or tissue engineering-based procedures and an overall increasing quality of the published studies.

CONCLUSION

This bibliometric analysis documented an increasing interest in cartilage surgery, with efforts toward high-quality studies. Over the years, the focus switched from reconstructive toward regenerative techniques, with emerging options including cell-free and tissue-engineering strategies to restore the cartilage surface.

LEVEL OF EVIDENCE

IV.

Retrospective Analysis of Autologous Chondrocyte-Based Cytotherapy Production for Clinical Use: GMP Process-Based Manufacturing Optimization in a Swiss University Hospital

Cultured autologous human articular chondrocyte (HAC) implantation has been extensively investigated for safe and effective promotion of structural and functional restoration of knee cartilage lesions. HAC-based cytotherapeutic products for clinical use must be manufactured under an appropriate quality assurance system and follow good manufacturing practices (GMP). A prospective clinical trial is ongoing in the Lausanne University Hospital, where the HAC manufacturing processes have been implemented internally. Following laboratory development and in-house GMP transposition of HAC cell therapy manufacturing, a total of 47 patients have been treated to date. The main aim of the present study was to retrospectively analyze the available manufacturing records of the produced HAC-based cytotherapeutic products, outlining the inter-individual variability existing among the 47 patients regarding standardized transplant product preparation. These data were used to ameliorate and to ensure the continued high quality of cytotherapeutic care in view of further clinical investigations, based on the synthetic analyses of existing GMP records. Therefore, a renewed risk analysis-based process definition was performed, with specific focus set on process parameters, controls, targets, and acceptance criteria. Overall, high importance of the interdisciplinary collaboration and of the manufacturing process robustness was underlined, considering the high variability (i.e., quantitative, functional) existing between the treated patients and between the derived primary HAC cell types.

Collagenase treatment appears to improve cartilage tissue integration but damage to collagen networks is likely permanent

When repairing cartilage defects a major challenge is achieving high-quality integration between the repair tissue and adjacent native cartilage. Matrix-rich cartilage is not easily remodeled, motivating several studies to trial enzyme treatment of the tissue interface to facilitate remodeling and integration. Studying and optimizing such processes is tedious, as well as potentially expensive, and thus simpler models are needed to evaluate the merits of enzyme treatment on cartilage tissue integration. Herein, we used engineered cartilage microtissues formed from bone marrow-derived stromal cells (BMSC) or expanded articular chondrocytes (ACh) to study the impact of enzyme treatment on cartilage tissue integration and matrix remodeling. A 5-min treatment with collagenase appeared to improve cartilage microtissue integration, while up to 48 h treatment with hyaluronidase did not. Alcian blue and anti-collagen II staining suggested that collagenase treatment did facilitate near seamless integration of cartilage microtissues. Microtissue sections were stained with Picrosirius red and characterized using polarized light microscopy, revealing that individual microtissues contained a collagen network organized in concentric shells. While collagenase treatment appeared to improve tissue integration, assessment of the collagen fibers with polarized light indicated that enzymatically damaged networks were not remodeled nor restored during subsequent culture. This model and these data paradoxically suggest that collagen network disruption is required to improve cartilage tissue integration, but that the disrupted collagen networks are unlikely to subsequently be restored. Future studies should attempt to limit collagen network disruption to the surface of the cartilage, and we recommend using Picrosirius red staining and polarized light to assess the quality of matrix remodeling and integration.

Repair of Osteochondritis Dissecans of the Lateral Femoral Condyle by a Trochlea Osteochondral Autograft: A Case Report

CASE

A 17-year-old adolescent boy with large deep osteochondritis dissecans (OCD) of the right lateral femoral condyle was treated with ipsilateral trochlea osteochondral autograft transplantation combined with iliac cancellous bone grafting to the donor site of the lateral trochlea. Both autografts were fused 3 months after surgery. It was radiographically confirmed that the OCD lesion was successfully reconstructed.

CONCLUSION

This procedure is an alternative surgical option for large and deep OCDs. It offers sufficient loading strength to the joint and adequate reconstruction of the congruent joint surface and can be performed at any regular facility.

Algorithm for Treatment of Focal Cartilage Defects of the Knee: Classic and New Procedures

OBJECTIVE

To create a treatment algorithm for focal grade 3 or 4 cartilage defects of the knee using both classic and novel cartilage restoration techniques.

DESIGN

A comprehensive review of the literature was performed highlighting classic as well as novel cartilage restoration techniques supported by clinical and/or basic science research and currently being employed by orthopedic surgeons.

RESULTS

There is a high level of evidence to support the treatment of small to medium size lesions (<2-4 cm2) without subchondral bone involvement with traditional techniques such as marrow stimulation, osteochondral autograft transplant (OAT), or osteochondral allograft transplant (OCA). Newer techniques such as autologous matrix-induced chondrogenesis and bone marrow aspirate concentrate implantation have also been shown to be effective in select studies. If subchondral bone loss is present OAT or OCA should be performed. For large lesions (>4 cm2), OCA or matrix autologous chondrocyte implantation (MACI) may be performed. OCA is preferred over MACI in the setting of subchondral bone involvement while cell-based modalities such as MACI or particulated juvenile allograft cartilage are preferred in the patellofemoral joint.

CONCLUSIONS

Numerous techniques exist for the orthopedic surgeon treating focal cartilage defects of the knee. Treatment strategies should be based on lesion size, lesion location, subchondral bone involvement, and the level of evidence supporting each technique in the literature.

Combination of a Collagen Scaffold and an Adhesive Hyaluronan-Based Hydrogel for Cartilage Regeneration: A Proof of Concept in an Ovine Model

OBJECTIVE

Hyaluronic acid-transglutaminase (HA-TG) is an enzymatically crosslinkable adhesive hydrogel with chondrogenic properties demonstrated in vitro and in an ectopic mouse model. In this study, we investigated the feasibility of using HA-TG in a collagen scaffold to treat chondral lesions in an ovine model, to evaluate cartilage regeneration in a mechanically and biologically challenging joint environment, and the influence of the surgical procedure on the repair process.

DESIGN

Chondral defects of 6-mm diameter were created in the stifle joint of skeletally mature sheep. In a 3-month study, 6 defects were treated with HA-TG in a collagen scaffold to test the stability and biocompatibility of the defect filling. In a 6-month study, 6 sheep had 12 defects treated with HA-TG and collagen and 2 sheep had 4 untreated defects. Histologically observed quality of repair tissue and adjacent cartilage was semiquantitatively assessed.

RESULTS

HA-TG adhered to the native tissue and did not cause any detectable negative reaction in the surrounding tissue. HA-TG in a collagen scaffold supported infiltration and chondrogenic differentiation of mesenchymal cells, which migrated from the subchondral bone through the calcified cartilage layer. Additionally, HA-TG and collagen treatment led to better adjacent cartilage preservation compared with empty defects (P < 0.05).

CONCLUSIONS

This study demonstrates that the adhesive HA-TG hydrogel in a collagen scaffold shows good biocompatibility, supports in situ cartilage regeneration and preserves the surrounding cartilage. This proof-of-concept study shows the potential of this approach, which should be further considered in the treatment of cartilage lesions using a single-step procedure.

Acute Cartilage Injury Induced by Trans-Articular Sutures

OBJECTIVE

To determine the extent of acute cartilage injury by using trans-articular sutures.

METHODS

Five different absorbable sutures, monofilament polydioxanone (PDS) and braided polyglactin (Vicryl), were compared on viable human osteochondral explants. An atraumatic needle with 30 cm of thread was advanced through the cartilage with the final thread left in the tissue. A representative 300 μm transversal slice from the cartilage midportion was stained with Live/Dead probes, scanned under the confocal laser microscope, and analyzed for the diameters of (a) central "Black zone" without any cells, representing in situ thread thickness and (b) "Green zone," including the closest Live cells, representing the maximum injury to the tissue. The exact diameters of suture needles and threads were separately measured under an optical microscope.

RESULTS

The diameters of the Black (from 144 to 219 µm) and the Green zones (from 282 to 487 µm) varied between the different sutures (P < 0.001). The Green/Black zone ratio remained relatively constant (from 1.9 to 2.2; P = 0.767). A positive correlation between thread diameters and PDS suturing material, toward the Black and Green zone, was established, but needle diameters did not reveal any influence on the zones.

CONCLUSIONS

The width of acute cartilage injury induced by the trans-articular sutures is about twice the thread thickness inside of the tissue. Less compressible monofilament PDS induced wider tissue injury in comparison to a softer braided Vicryl. Needle diameter did not correlate to the extent of acute cartilage injury.

Surgical management of focal chondral defects of the knee: a Bayesian network meta-analysis

Background

Focal chondral defects of the knee are common. Several surgical techniques have been proposed for the management of chondral defects: microfractures (MFX), osteochondral autograft transplantation (OAT), autologous matrix-induced chondrogenesis (AMIC) and autologous chondrocyte implantation (ACI)—first generation (pACI), second generation (cACI) and third generation (mACI). A Bayesian network meta-analysis was conducted to compare these surgical strategies for chondral defects in knee at midterm follow-up.

Methods

This Bayesian network meta-analysis was conducted according to the PRISMA extension statement for reporting of systematic reviews incorporating network meta-analyses of health care interventions. PubMed, Google Scholar, Embase and Scopus databases were accessed in July 2021. All the prospective comparative clinical trials investigating two or more surgical interventions for chondral defects of the knee were accessed. The network meta-analyses were performed through a Bayesian hierarchical random-effects model analysis. The log odds ratio (LOR) effect measures were used for dichotomic variables, while the standardized mean difference (SMD) for the continuous variables.

Results

Data from 2220 procedures (36 articles) were retrieved. The median follow-up was 36 (24 to 60) months. The ANOVA test found good baseline comparability between symptoms duration, age, sex and body mass index. AMIC resulted in higher Lysholm score (SMD 3.97) and Tegner score (SMD 2.10). AMIC demonstrated the lowest rate of failures (LOR −0.22) and the lowest rate of revisions (LOR 0.89). As expected, MFX reported the lower rate of hypertrophy (LOR −0.17) followed by AMIC (LOR 0.21). No statistically significant inconsistency was found in the comparisons.

Conclusion

AMIC procedure for focal chondral defects of the knee performed better overall at approximately 3 years’ follow-up.

Hydrogel Composites with Different Dimensional Nanoparticles for Bone Regeneration

The treatment of large segmental bone defects and complex types of fractures caused by trauma, inflammation, or tumor resection is still a challenge in the field of orthopedics. Various natural or synthetic biological materials used in clinical applications cannot fully replicate the structure and performance of raw bone. This highlights how to endow materials with multiple functions and biological properties, which is a problem that needs to be solved in practical applications. Hydrogels with outstanding biocompatibility, for their casting into any shape, size, or form, are suitable for different forms of bone defects. Therefore, they have been used in regenerative medicine more widely. In this review, versatile hydrogels are compounded with nanoparticles of different dimensions, and many desirable features of these materials in bone regeneration are introduced, including drug delivery, cell factor vehicle, cell scaffolds, which have potential in bone regeneration applications. The combination of hydrogels and nanoparticles of different dimensions encourages better filling of bone defect areas and has higher adaptability. This is due to the minimally invasive properties of the material and ability to match irregular defects. These biological characteristics make composite hydrogels with different dimensional nanoparticles become one of the most attractive options for bone regeneration materials.

Arthroscopic Subchondral Drilling Followed by Injection of Peripheral Blood Stem Cells and Hyaluronic Acid Showed Improved Outcome Compared to Hyaluronic Acid and Physiotherapy for Massive Knee Chondral Defects: A Randomized Controlled Trial

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of intra-articular injections of autologous peripheral blood stem cells (PBSCs) plus hyaluronic acid (HA) after arthroscopic subchondral drilling into massive chondral defects of the knee joint and to determine whether PBSC therapy can improve functional outcome and reduce pain of the knee joint better than HA plus physiotherapy.

METHODS

This is a dual-center randomized controlled trial (RCT). Sixty-nine patients aged 18 to 55 years with International Cartilage Repair Society grade 3 and 4 chondral lesions (size ≥3 cm²) of the knee joint were randomized equally into (1) a control group receiving intra-articular injections of HA plus physiotherapy and (2) an intervention group receiving arthroscopic subchondral drilling into chondral defects and postoperative intra-articular injections of PBSCs plus HA. The coprimary efficacy endpoints were subjective International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS)-pain subdomain measured at month 24. The secondary efficacy endpoints included all other KOOS subdomains, Numeric Rating Scale (NRS), and Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scores.

RESULTS

At 24 months, the mean IKDC scores for the control and intervention groups were 48.1 and 65.6, respectively (P < .0001). The mean for KOOS-pain subdomain scores were 59.0 (control) and 86.0 (intervention) with P < .0001. All other KOOS subdomain, NRS, and MOCART scores were statistically significant (P < .0001) at month 24. Moreover, for the intervention group, 70.8% of patients had IKDC and KOOS-pain subdomain scores exceeding the minimal clinically important difference values, indicating clinical significance. There were no notable adverse events that were unexpected and related to the study drug or procedures.

CONCLUSIONS

Arthroscopic marrow stimulation with subchondral drilling into massive chondral defects of the knee joint followed by postoperative intra-articular injections of autologous PBSCs plus HA is safe and showed a significant improvement of clinical and radiologic scores compared with HA plus physiotherapy.

LEVEL OF EVIDENCE

Level I, RCT.

Enhanced expression of hyaluronic acid in osteoarthritis-affected knee-cartilage chondrocytes during three-dimensional in vitro culture in a hyaluronic-acid-retaining polymer scaffold

BACKGROUND

Chondrocyte transplantation to address cartilage damage is an established solution. Because hyaluronic acid (HA) is an essential component for homeostasis of the cartilage, in order to arrive at methodologies to utilize its advantages in cell-based therapies, we compared the HA retention capability of a thermoreversible gelation polymer scaffold-based environment (3D-TGP) with conventional in vitro cell culture methodologies.

METHODS

Chondrocytes derived from osteoarthritis-affected knee joint cartilage of elderly patients were used and accomplished in three phases. In Phase I, the levels of HA secreted by chondrocytes were measured in culture supernatant. In Phase II, retention capacity of externally added HA was quantified indirectly by measuring the HA released in culture supernatant, and in Phase III, the expression of CD44 on cells was analysed by immunohistochemistry.

RESULTS

In Phase I, the average HA in the 3D supernatant was 3% that of 2D. In phase II, 80% of externally added HA was detected in the 2D on day 7, while in 3D-TGP, only 0.1% was released until day 21. In Phase III, 2D yielded individual cells that started degenerating from the third week; in 3D-TGP cells grew for a longer duration, formed a tissue-like architecture with extracellular matrix with significantly intense staining of CD44 than 2D.

CONCLUSION

The capability of the 3D-TGP culture environment to retain HA and support chondrocytes to grow with a tissue-like architecture expressing higher HA content is considered advantageous as it serves as an in vitro culture platform that enables tissue engineering of cartilage tissue with native hyaline phenotype and higher HA expression. The in vitro environment being conducive, based on this data, we also recommend that the TGP be tried as an encapsulation material in clinical studies of chondrocyte implantation for optimal clinical outcome.

Development of Standardized Fetal Progenitor Cell Therapy for Cartilage Regenerative Medicine: Industrial Transposition and Preliminary Safety in Xenogeneic Transplantation

Diverse cell therapy approaches constitute prime developmental prospects for managing acute or degenerative cartilaginous tissue affections, synergistically complementing specific surgical solutions. Bone marrow stimulation (i.e., microfracture) remains a standard technique for cartilage repair promotion, despite incurring the adverse generation of fibrocartilagenous scar tissue, while matrix-induced autologous chondrocyte implantation (MACI) and alternative autologous cell-based approaches may partly circumvent this effect. Autologous chondrocytes remain standard cell sources, yet arrays of alternative therapeutic biologicals present great potential for regenerative medicine. Cultured human epiphyseal chondro-progenitors (hECP) were proposed as sustainable, safe, and stable candidates for chaperoning cartilage repair or regeneration. This study describes the development and industrial transposition of hECP multi-tiered cell banking following a single organ donation, as well as preliminary preclinical hECP safety. Optimized cell banking workflows were proposed, potentially generating millions of safe and sustainable therapeutic products. Furthermore, clinical hECP doses were characterized as non-toxic in a standardized chorioallantoic membrane model. Lastly, a MACI-like protocol, including hECPs, was applied in a three-month GLP pilot safety evaluation in a caprine model of full-thickness articular cartilage defect. The safety of hECP transplantation was highlighted in xenogeneic settings, along with confirmed needs for optimal cell delivery vehicles and implantation techniques favoring effective cartilage repair or regeneration.

Managing Chondral Lesions: A Literature Review and Evidence-Based Clinical Guidelines

BACKGROUND

Articular cartilage lesions are becoming increasingly common. Optimum diagnosis and management of chondral defects cause a lot of dilemma. A number of surgical methods have been reported in the literature for treating focal cartilage defects. There is a lack of consensus on the most effective management strategy, with newer surgical and cell-based treatments being advocated regularly.

STUDY DESIGN AND METHODS

A clinical review is constructed by appraising the published literature about clinical evaluation and diagnostic modalities for articular cartilage defects and subsequent surgical procedures, management strategies employed for such lesions. Prominent available databases (PUBMED, EMBASE, Cochrane) were also searched for trials comparing functional outcomes following cartilage procedures. Synthesis of a practical management guideline is then attempted based on the evidence assessed.

RESULTS

Systematic examination and optimal use of diagnostic imaging are an important facet of cartilage defect management. Patient and lesion factors greatly influence the outcome of cartilage procedures and must be considered while planning management. Smaller lesions < 2 cm² respond well to all treatment modalities. Autologous osteochondral transplants (OATs) are effective in high activity individuals with intermediate lesions. For larger lesions > 4 cm², newer generation autologous chondrocyte implantation (ACI) has shown promising and durable results. Stem cells with scaffolds may provide an alternate option. Orthobiologics are a useful adjunct to the surgical procedures, but need further evaluation.

CONCLUSIONS

Most treatment modalities have their role in appropriate cases and management needs to be individualized for patients. The search for the perfect cartilage restoration procedure continues.

Characterization of Properties, In Vitro and In Vivo Evaluation of Calcium Phosphate/Amino Acid Cements for Treatment of Osteochondral Defects

Novel calcium phosphate cements containing a mixture of four amino acids, glycine, proline, hydroxyproline and either lysine or arginine (CAL, CAK) were characterized and used for treatment of artificial osteochondral defects in knee. It was hypothesized that an enhanced concentration of extracellular collagen amino acids (in complex mixture), in connection with bone cement in defect sites, would support the healing of osteochondral defects with successful formation of hyaline cartilage and subchondral bone. Calcium phosphate cement mixtures were prepared by in situ reaction in a planetary ball mill at aseptic conditions and characterized. It was verified that about 30–60% of amino acids remained adsorbed on hydroxyapatite particles in cements and the addition of amino acids caused around 60% reduction in compressive strength and refinement of hydroxyapatite particles in their microstructure. The significant over-expression of osteogenic genes after the culture of osteoblasts was demonstrated in the cement extracts containing lysine and compared with other cements. The cement pastes were inserted into artificial osteochondral defects in the medial femoral condyle of pigs and, after 3 months post-surgery, tissues were analyzed macroscopically, histologically, immunohistochemically using MRI and X-ray methods. Analysis clearly showed the excellent healing process of artificial osteochondral defects in pigs after treatment with CAL and CAK cements without any inflammation, as well as formation of subchondral bone and hyaline cartilage morphologically and structurally identical to the original tissues. Good integration of the hyaline neocartilage with the surrounding tissue, as well as perfect interconnection between the neocartilage and new subchondral bone tissue, was demonstrated. Tissues were stable after 12 months’ healing.

Ex Vivo Systems to Study Chondrogenic Differentiation and Cartilage Integration

Articular cartilage injury and repair is an issue of growing importance. Although common, defects of articular cartilage present a unique clinical challenge due to its poor self-healing capacity, which is largely due to its avascular nature. There is a critical need to better study and understand cellular healing mechanisms to achieve more effective therapies for cartilage regeneration. This article aims to describe the key features of cartilage which is being modelled using tissue engineered cartilage constructs and ex vivo systems. These models have been used to investigate chondrogenic differentiation and to study the mechanisms of cartilage integration into the surrounding tissue. The review highlights the key regeneration principles of articular cartilage repair in healthy and diseased joints. Using co-culture models and novel bioreactor designs, the basis of regeneration is aligned with recent efforts for optimal therapeutic interventions.

Clinical, radiological, and histological outcomes after the fibrin-matrix autologous chondrocyte implantation for chondral lesions of the knee in patients more than 50 years old: A prospective case series with minimum 2-year follow-up

BACKGROUND

The purpose of this study was to evaluate clinical and radiological outcomes and to analyze the histological findings of repaired cartilage in patients more than 50 years old with underwent fibrin-matrix autologous chondrocyte implantation (ACI).

METHODS

From January 2013 to February 2014, a prospective study was conducted on 16 patients (16 knees) who underwent fibrin-matrix ACI for International Cartilage Repair Society grade 3 or 4 chondral lesions of the knee. The major lesion was in the medial femoral condyle in all patients. The mean age of the patients was 58.1 ± 6.2 (range 51-66) years, and the minimum follow-up period was 2 years. All patients had clinical and radiological evaluations at 3 months, 6 months, 1 year, and 2 years after surgery. Twelve patients had second-look arthroscopies at 1 year after surgery, and implanted chondral biopsies were performed in 11 of these 12 patients for histological analysis.

RESULTS

Functional disability assessment scales for the knee significantly improved after fibrin-matrix ACI (p < 0.05). The visual analog scale score significantly decreased from 6.7 ± 1.2 to 2.0 ± 1.8 (p < 0.001). The mean modified magnetic resonance observation of cartilage repair tissue score was 83.8 ± 17.3 at 1 year after surgery and 74.0 ± 19.2 at 2 years after surgery. Repair of the tissue with hyaline cartilage was confirmed histologically.

CONCLUSIONS

Satisfactory clinical and radiological outcomes were obtained from gel-type fibrin-matrix ACI technique in older patients with a cartilage defect of the knee. Histological analysis confirmed that the new repaired tissue with hyaline cartilage filled the cartilage defect area. Therefore, fibrin-matrix ACI is believed to be an applicable treatment for older patients with chondral lesions of the knee.

LEVEL OF EVIDENCE

Level IV.

Holistic Approach of Swiss Fetal Progenitor Cell Banking: Optimizing Safe and Sustainable Substrates for Regenerative Medicine and Biotechnology

Safety, quality, and regulatory-driven iterative optimization of therapeutic cell source selection has constituted the core developmental bedrock for primary fetal progenitor cell (FPC) therapy in Switzerland throughout three decades. Customized Fetal Transplantation Programs were pragmatically devised as straightforward workflows for tissue procurement, traceability maximization, safety, consistency, and robustness of cultured progeny cellular materials. Whole-cell bioprocessing standardization has provided plethoric insights into the adequate conjugation of modern biotechnological advances with current restraining legislative, ethical, and regulatory frameworks. Pioneer translational advances in cutaneous and musculoskeletal regenerative medicine continuously demonstrate the therapeutic potential of FPCs. Extensive technical and clinical hindsight was gathered by managing pediatric burns and geriatric ulcers in Switzerland. Concomitant industrial transposition of dermal FPC banking, following good manufacturing practices, demonstrated the extensive potential of their therapeutic value. Furthermore, in extenso, exponential revalorization of Swiss FPC technology may be achieved via the renewal of integrative model frameworks. Consideration of both longitudinal and transversal aspects of simultaneous fetal tissue differential processing allows for a better understanding of the quasi-infinite expansion potential within multi-tiered primary FPC banking. Multiple fetal tissues (e.g., skin, cartilage, tendon, muscle, bone, lung) may be simultaneously harvested and processed for adherent cell cultures, establishing a unique model for sustainable therapeutic cellular material supply chains. Here, we integrated fundamental, preclinical, clinical, and industrial developments embodying the scientific advances supported by Swiss FPC banking and we focused on advances made to date for FPCs that may be derived from a single organ donation. A renewed model of single organ donation bioprocessing is proposed, achieving sustained standards and potential production of billions of affordable and efficient therapeutic doses. Thereby, the aim is to validate the core therapeutic value proposition, to increase awareness and use of standardized protocols for translational regenerative medicine, potentially impacting millions of patients suffering from cutaneous and musculoskeletal diseases. Alternative applications of FPC banking include biopharmaceutical therapeutic product manufacturing, thereby indirectly and synergistically enhancing the power of modern therapeutic armamentariums. It is hypothesized that a single qualifying fetal organ donation is sufficient to sustain decades of scientific, medical, and industrial developments, as technological optimization and standardization enable high efficiency.

An Assessment of Randomized Controlled Trial Quality in The Journal of Bone & Joint Surgery: Update from 2001 to 2013

BACKGROUND

The quality of reporting of randomized controlled trials (RCTs) published in The Journal of Bone & Joint Surgery (JBJS) from 1988 to 2000 was previously analyzed. The purpose of this current study was to analyze the quality of reporting of RCTs published in JBJS from 2001 to 2013 to identify trends over time and potential areas of improvement for future clinical trials.

METHODS

A manual search of the JBJS database identified RCTs published between January 2001 and December 2013. Quality assessments, using the Detsky quality-of-reporting index (Detsky score), a modified Cochrane risk-of-bias tool, and abstraction of relevant data identifying predictors of quality, were conducted.

RESULTS

A total of 5,780 publications were identified in JBJS from 2001 to 2013, with 285 RCTs (4.9%), representing an increase from the prior 13-year period. The overall mean transformed Detsky score (and standard error) increased significantly (p < 0.001) from 68.1% ± 1.67% to 76.24% ± 0.72%. The percentage of multicenter RCTs decreased from 67% to 31%. The percentage of positive trials also decreased from 80% to 50.5%, as did the mean sample size (212 to 166). Regression analysis indicated that trials with an epidemiologist as the first author and nonsurgical trials were significantly associated (p = 0.001) with a higher overall trial quality score. The categories of the lowest mean methodology scores were randomization and concealment, eligibility criteria, and reasons for patient exclusion, as identified with the Detsky score, and patient and assessor blinding, as identified with the risk-of-bias assessment.

CONCLUSIONS

The quantity and quality of published RCTs in JBJS have increased in the 2001 to 2013 time period compared with the previous time period. Although these improvements are encouraging, trends to smaller, single-center trials were also observed. To efficiently determine the efficacy of orthopaedic treatments and limit bias, high-quality randomized trials of appropriate sample size and rigorous design are needed.

A tri-component knee plug for the 3rd generation of autologous chondrocyte implantation

Here, we report a newly designed knee plug to be used in the 3rd generation of Autologous Chondrocyte Implantation (ACI) in order to heal the damaged knee cartilage. It is composed of three components: The first component (Bone Portion) is a 3D printed hard scaffold with large pores (~ 850 µm), made by hydroxyapatite and β-tricalcium phosphate to accommodate the bony parts underneath the knee cartilage. It is a cylinder with a diameter of 20 mm and height of 7.5 mm, with a slight dome shape on top. The plug also comprises a Cartilage Portion (component 2) which is a 3D printed gelatin/elastin/sodium-hyaluronate soft thick porous membrane with large pores to accommodate chondrocytes. Cartilage Portion is secured on top of the Bone Portion using mechanical interlocking by designing specific knobs in the 3D printed construct of the Cartilage Portion. The third component of the plug (Film) is a stitchable permeable membrane consisting of polycaprolactone (PCL) on top of the Cartilage Portion to facilitate sliding of the knee joint and to hold the entire plug in place while allowing nutrients delivery to the Cartilage Portion. The PCL Film is prepared using a combination of film casting and sacrificial material leaching with a pore size of 10 µm. It is surface modified to have specific affinity with the Cartilage Portion. The detailed design criteria and production process of this plug is presented in this report. Full in vitro analyses have been performed, which indicate the compatibility of the different components of the plug relative to their expected functions.

Simultaneous Recruitment of Stem Cells and Chondrocytes Induced by a Functionalized Self-Assembling Peptide Hydrogel Improves Endogenous Cartilage Regeneration

The goal of treating articular cartilage (AC) injury is to regenerate cartilage tissue and to integrate the neo-cartilage with surrounding host cartilage. However, most current studies tend to focus on engineering cartilage; interface integration has been somewhat neglected. An endogenous regenerative strategy that simultaneously increases the recruitment of bone marrow mesenchymal stem cells (BMSCs) and chondrocytes may improve interface integration and cartilage regeneration. In this study, a novel functionalized self-assembling peptide hydrogel (KLD-12/KLD-12-LPP, KLPP) containing link protein N-peptide (LPP) was designed to optimize cartilage repair. KLPP hydrogel was characterized using transmission electron microscopy (TEM) and rheometry. KLPP hydrogel shared a similar microstructure to KLD-12 hydrogel which possesses a nanostructure with a fiber diameter of 25–35 nm. In vitro experiments showed that KLPP hydrogel had little cytotoxicity, and significantly induced chondrocyte migration and increased BMSC migration compared to KLD-12 hydrogel. In vivo results showed that defects treated with KLPP hydrogel had higher overall International Cartilage Repair Society (ICRS) scores, Safranin-O staining scores and cumulative histology scores than untreated defects or defects treated with KLD-12 hydrogel, although defects treated with KLD-12 and KLPP hydrogels received similar type II collagen immunostaining scores. All these findings indicated that the simple injectable functionalized self-assembling peptide hydrogel KLPP facilitated simultaneous recruitment of endogenous chondrocytes and BMSCs to promote interface integration and improve cartilage regeneration, holding great potential as a one-step surgery strategy for endogenous cartilage repair.

Articular chondrocytes from osteoarthritic knee joints of elderly, in vitro expanded in thermo-reversible gelation polymer (TGP), exhibiting higher UEA-1 expression in lectin microarray

Autologous chondrocytes in vitro expanded, are used as tools of regenerative therapies for cartilage injuries. However, inability to maintain the hyaline phenotype both in vitro and post in vivo transplantation, remains one of the major hurdles for long term efficacy under clinical settings. We have reported earlier, hyaline phenotype maintenance of both human and rabbit chondrocytes for a long duration both in vitro when cultured conditions using a Thermo-reversible Gelation Polymer (TGP) scaffold-based methodology and in vivo post-transplantation animal model of cartilage damage. Having intrigued by such encouraging outcome, we in this study, analysed the similar TGP culture environment whether would be able to allow in vitro expansion of severe osteoarthritis affected cartilage tissue from elderly patients and evaluated the cells using lectin microarray characterization for pluripotency. Cartilage tissue were obtained from patients (n = 7; age: 60–85 years) undergoing total knee arthroplasty for severe osteoarthritis. Chondrocytes were isolated and cultured in two groups: i. conventional culture without scaffold (2D) and ii. using a TGP scaffold-based culture (3D) up to 18 weeks. In addition to earlier reported findings such as maintenance of hyaline phenotype having been confirmed in this study as well, surface glycoprotein analysis by lectin microarray demonstrated that the α1-2 Fuc recognition lectin (UEA-1) (marker reported in literature for pluripotent stem cells) was found to be more highly expressed in 3D culture compared to 2D culture and even increased over time in 3D culture. We have developed an environment where osteoarthritis affected chondrocytes from the elderly could be cultured up to 18 weeks in vitro using TGP scaffold which express pluripotent cell associated surface glycoproteins compared to the conventional methodology.

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Good quality chondrocytes were grown from cartilage tissue of elderly with severe osteoarthritis for 18 weeks in vitro.

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Inflamed donor chondrocytes could be revived to form normal tissue in a 3D in vitro TGP scaffold environment.

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Pluripotent stem cell marker UEA-1 in Lectin microarray was positive in TGP- Polymer scaffold grown cartilage.

Anisotropic properties of articular cartilage in an accelerated in vitro wear test

Many material properties of articular cartilage are anisotropic, particularly in the superficial zone where collagen fibers have a preferential direction. However, the anisotropy of cartilage wear had not been previously investigated. The objective of this study was to evaluate the anisotropy of cartilage material behavior in an in vitro wear test. The wear and coefficient of friction of bovine condylar cartilage were measured with loading in directions parallel (longitudinal) and orthogonal (transverse) to the collagen fiber orientation at the articular surface. An accelerated cartilage wear test was performed against a T316 stainless-steel plate in a solution of phosphate buffered saline with protease inhibitors. A constant load of 160 N was maintained for 14000 cycles of reciprocal sliding motion at 4 mm/s velocity and a travel distance of 18 mm in each direction. The contact pressure during the wear test was approximately 2 MPa, which is in the range of that reported in the human knee and hip joint. Wear was measured by biochemically quantifying the glycosaminoglycans (GAGs) and collagen that was released from the tissue during the wear test. Collagen damage was evaluated with collagen hybridizing peptide (CHP), while visualization of the tissue composition after the wear test was provided with histologic analysis. Results demonstrated that wear in the transverse direction released about twice as many GAGs than in the longitudinal direction, but that no significant differences were seen in the amount of collagen released from the specimens. Specimens worn in the transverse direction had a higher intensity of CHP stain than those worn in the longitudinal direction, suggesting more collagen damage from wear in the transverse direction. No anisotropy in friction was detected at any point in the wear test. Histologic and CHP images demonstrate that the GAG loss and collagen damage extended through much of the depth of the cartilage tissue, particularly for wear in the transverse direction. These results highlight distinct differences between cartilage wear and the wear of traditional engineering materials, and suggest that further study on cartilage wear is warranted. A potential clinical implication of these results is that orienting osteochondral grafts such that the direction of wear is aligned with the primary fiber direction at the articular surface may optimize the life of the graft.

Management of the Failed OCD

PURPOSE OF THE REVIEW

Osteochondritis dissecans (OCD) is a pathologic condition of subchondral bone most frequently occurring in the medial femoral condyle of the knee in children and adolescents. Salvage techniques are necessary when either nonoperative or typical operative treatments fail, or the OCD presents in an unsalvageable state. The purpose of this review is to describe the evaluation and management of failed OCDs.

RECENT FINDINGS

Thorough preoperative planning is essential to the treatment of failed OCDs. Radiographs and advanced imaging such as MRI and CT allow for a detailed assessment of subchondral bone and cartilage. Long-leg alignment radiographs are critical to assess for malalignment which may increase the contact forces on the affected condyle. Malalignment can be corrected with hemiepiphysiodesis or an osteotomy depending on the skeletal maturity of the patient. Osteochondral allografts and autologous chondrocyte implantation treat the defect in both bone and cartilage or solely cartilage and have good short to moderate term outcomes, particularly as compared to the inferior outcomes of microfracture of larger OCDs. Osteochondritis dissecans of the knee that fails to heal with initial operative measures can result in a large defect of bone and cartilage in the knee of adolescents. Treatment of the bone and cartilage defect can be accomplished with either osteochondral allograft transplantation or matrix-assisted autologous chondrocyte implantation can be performed with good outcomes. Assessment and correction of lower extremity malalignment is a critical component of treatment. Durable long-term solutions are necessary for the treatment of these difficult lesions.

Long-term results of reconstructing the joints' articular surface in the knee and ankle with the surgical diamond instrumentation (SDI)

PURPOSE

The surgical diamond instrumentation (SDI), a precise wet-grinding technology, promised contact healing of press-fit inserted bone and even hyaline cartilage, lacks medium- and long-term results. This retrospective study was conducted to identify risk factors associated with the failure of the technique and the subjective patient outcome.

METHODS

All patients treated for cartilage defects of the knee or ankle joint using the SDI technology between 2000 and 2012 with a follow-up > 1 year were included. Patients with general joint diseases or joint-related procedures, except for corrective osteotomies, were excluded. A standardized questionnaire (EQ-5D) and a questionnaire-based patient-reported outcome survey were used. Descriptive statistics were applied. A multivariate analysis examining risk factors for joint failure was performed. A p value < 0.05 was considered to indicate significant differences.

RESULTS

87 patients with autologous osteochondral transplantation (68 knee, 19 ankle) were included. The median age was 53 years (IQR 37.5-63.0 years) for knee and 36 years (IQR 27.5-54.0 years) for ankle joints. 57.9% of knee and 55.6% of ankle patients were female. Nine patients (8 knee, 1 ankle) had received arthroplasty. 93.3% of knee and 83.3% of ankle patients had an excellent function or minor disabilities. 73.3% of knee and 64.7% of ankle patients did not require pain medication. The mean EQ-5D score was 0.84 for knee and 0.77 for ankle. Patients with higher age were more likely to receive arthroplasty (p = 0.022).

CONCLUSIONS

The SDI technique provides promising results with excellent joint survival rates and satisfying patient-reported outcomes. Failure of the technique might be associated with higher age.

Polymeric mesh and insulin-like growth factor 1 delivery enhance cell homing and graft-cartilage integration

Cartilage injury, such as full-thickness lesions, predisposes patients to the premature development of osteoarthritis, a degenerative joint disease. While surgical management of cartilage lesions has improved, long-term clinical efficacy has stagnated, owing to the lack of hyaline cartilage regeneration and inadequate graft-host integration. This study tests the hypothesis that integration of cartilage grafts with native cartilage can be improved by enhancing the migration of chondrocytes across the graft-host interface via the release of chemotactic factor from a degradable polymeric mesh. To this end, a polylactide-co-glycolide/poly-ε-caprolactone mesh was designed to localize the delivery of insulin-like growth factor 1 (IGF-1), a well-established chondrocyte attractant. The release of IGF-1 (100 ng/mg) enhanced cell migration from cartilage explants, and the mesh served as critical structural support for cell adhesion, growth, and production of a cartilaginous matrix in vitro, which resulted in increased integration strength compared with mesh-free repair. Further, this neocartilage matrix was structurally contiguous with native and grafted cartilage when tested in an osteochondral explant model in vivo. These results demonstrate that this combined approach of a cell homing factor and supportive matrix will promote cell-mediated integrative cartilage repair and improve clinical outcomes of cartilage grafts in the treatment of osteoarthritis.

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.

Comparative Effectiveness of Cartilage Repair With Respect to the Minimal Clinically Important Difference

BACKGROUND

Recent studies demonstrated a 5% increase in cartilage repair procedures annually in the United States. There is currently no consensus regarding a superior technique, nor has there been a comprehensive evaluation of postoperative clinical outcomes with respect to a minimal clinically important difference (MCID).

PURPOSE

To determine the proportion of available cartilage repair studies that meet or exceed MCID values for clinical outcomes improvement over short-, mid-, and long-term follow-up.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review was performed via the Medline, Scopus, and Cochrane Library databases. Available studies were included that investigated clinical outcomes for microfracture (MFX), osteoarticular transfer system (OATS), osteochondral allograft transplantation, and autologous chondrocyte implantation/matrix-induced autologous chondrocyte implantation (ACI/MACI) for the treatment of symptomatic knee chondral defects. Cohorts were combined on the basis of surgical intervention by performing a meta-analysis that utilized inverse-variance weighting in a DerSimonian-Laird random effects model. Weighted mean improvements in International Knee Documentation Committee (IKDC), Lysholm, and visual analog scale for pain (VAS pain) scores were calculated from preoperative to short- (1-4 years), mid- (5-9 years), and long-term (≥10 years) postoperative follow-up. Mean values were compared with established MCID values per 2-tailed 1-sample Student t tests.

RESULTS

A total of 89 studies with 3894 unique patients were analyzed after full-text review. MFX met MCID values for all outcome scores at short- and midterm follow-up with the exception of VAS pain in the midterm. OATS met MCID values for all outcome scores at all available time points; however, long-term data were not available for VAS pain. Osteochondral allograft transplantation met MCID values for IKDC at short- and midterm follow-up and for Lysholm at short-term follow-up, although data were not available for other time points or for VAS pain. ACI/MACI met MCID values for all outcome scores (IKDC, Lysholm, and VAS pain) at all time points.

CONCLUSION

In the age of informed consent, it is important to critically evaluate the clinical outcomes and durability of cartilage surgery with respect to well-established standards of clinical improvement. MFX failed to maintain VAS pain improvements above MCID thresholds with follow-up from 5 to 9 years. All cartilage repair procedures met MCID values at short- and midterm follow-up for IKDC and Lysholm scores; ACI/MACI and OATS additionally met MCID values in the long term, demonstrating extended maintenance of clinical benefits for patients undergoing these surgical interventions as compared with MFX.

Continuous Low-Intensity Ultrasound Promotes Native-to-Native Cartilage Integration

Failure of the host/graft interface to integrate impedes the success of cartilage repair protocols. Continuous low-intensity ultrasound (cLIUS) at the resonant frequency of 5 MHz is proposed as a treatment modality for promoting native-to-native cartilage integration in vitro. Cylindrical incisions (4 mm) simulating chondral discontinuity were made in bovine cartilage and osteochondral explants, and maintained under cLIUS stimulation (14 kPa [5 MHz, 2.5 Vpp], 20 min, four times/day) for 28 days. Incised cartilage and osteochondral explants were categorized into three study groups; Group I: cLIUS was applied immediately upon incision; Group II: cLIUS was applied after 14 days following incision; Group-III: after 14 days following incision, explants were treated with 0.1% hyaluronidase and 30 U/mL collagenase VII. As a separate study group, incised osteochondral explants were treated immediately with cLIUS at a nonresonant frequency of 2 MHz (14 kPa [2 MHz, 6 Vpp], 20 min, four times/day). Cellular migration was analyzed by scratch assays, and by visualizing migrating cells into the hydrogel core of cartilage/hydrogel constructs. Explants under cLIUS (5 MHz) displayed higher percent apposition along with gap closures when compared with untreated controls and explants treated with cLIUS at 2 MHz. cLIUS (5 MHz)-treated explants were immunopositive for type II collagen. The strength of native-to-native cartilage integration was higher (p = 0.005) in cLIUS-treated cartilage explants at 0.19 ± 0.08 MPa as compared with 0.05 ± 0.03 MPa in untreated controls. Enhanced cartilage phenotype coupled with increased cellular migration were noted under cLIUS (5 MHz), alluding to the observed integration between cartilage interfaces. Collectively, cLIUS at cell resonant frequency promoted integrative cartilage repair, therefore, has the potential to improve cartilage repair outcomes. Impact Statement Lack of integration between the host and graft cartilage interfaces impedes the success of cartilage repair techniques. Continuous low-intensity ultrasound (cLIUS) is documented to induce chondrogenesis and chondrocyte phenotype. However, integrative cartilage repair under cLIUS has not been evaluated. Our results demonstrated integration between cartilage interfaces, increased percent apposition, increased strength of integration, and maintenance of cartilage phenotype under cLIUS (5 MHz). Integrative repair under cLIUS (5 MHz) stemmed from enhanced migration of cells and increased expression of cartilage-specific genes, namely SOX9 and COL2A1. Thus, cLIUS has the potential to improve the outcomes of grafting protocols for cartilage repair.

Cartilage repair surgery prevents progression of knee degeneration

PURPOSE

To investigate, whether cartilage repair surgery for focal osteochondral defects at the knee results in less degenerative changes over 6 years in a MR imaging follow-up than morphologically initially identical defects in non-operated control subjects from the osteoarthritis initiative (OAI).

METHODS

A total of 32 individuals received baseline and follow-up MRI. In n = 16 patients with cartilage repair [osteochondral autograft transfer system (OATS), n = 12; spongiosa-augmented matrix-associated autologous chondrocyte implantation (MACI), n = 4] MRI was performed preoperatively and after 5.7 ± 2.3 year follow-up. Baseline MRIs of non-operated subjects from the OAI were screened for initially identical cartilage defects (n = 16). Morphological knee abnormalities were assessed using WORMS, AMADEUS and MOCART scores. A sagittal 2D MSME sequence was implemented for quantitative cartilage T2 relaxation time measurements in all (0, 2, 4, 6 and 8-years) follow-ups from the OAI and in the postoperative MRI protocol.

RESULTS

For both groups, focal osteochondral defects were located at the femoral condyle in 8/16 cases (5 medial, 3 lateral) and at the patella in 8/16 cases. At baseline, the mean cartilage defect size ± SD was 1.4 ± 1.3 cm² for the control group and 1.3 ± 1.2 cm² for the cartilage repair group (n.s.). WORMS scores were not significantly different between the cartilage repair group and the control group at baseline [mean difference ± SEM (95%CI); 0.5 ± 2.5 (- 4.7, 5.7), n.s.]. During identical follow-up times, the progression of total WORMS scores [19.9 ± 2.3 (15.0, 24.9), P < 0.001] and of cartilage defects scores in the affected (P < 0.001) and in the opposing (P = 0.029) compartment was significantly more severe in non-operated individuals (P < 0.05). In non-operated subjects, T2 values increased continuously from baseline to the 8-year follow-up (P = 0.001).

CONCLUSIONS

Patients with cartilage repair showed less progression of degenerative MRI changes at 6-year follow-up than a control cohort from the OAI with initially identical osteochondral defects. Patients with focal cartilage defects may profit from cartilage repair surgery since it may prevent progression of early osteoarthritis at the knee joint.

LEVEL OF EVIDENCE

Prognostic study, Level II.

Beyond Cartilage Repair: The Role of the Osteochondral Unit in Joint Health and Disease

Once believed to be limited to articular cartilage, osteoarthritis is now considered to be an organ disease of the “whole joint.” Damage to the articular surface can lead to, be caused by, or occur in parallel with, damage to other tissues in the joint. The relationship between cartilage and the underlying subchondral bone has particular importance when assessing joint health and determining treatment strategies. The articular cartilage is anchored to the subchondral bone through an interface of calcified cartilage, which as a whole makes up the osteochondral unit. This unit functions primarily by transferring load-bearing weight over the joint to allow for normal joint articulation and movement. Unfortunately, irreversible damage and degeneration of the osteochondral unit can severely limit joint function. Our understanding of joint pain, the primary complaint of patients, is poorly understood and past efforts toward structural cartilage restoration have often not been associated with a reduction in pain. Continued research focusing on the contribution of subchondral bone and restoration of the entire osteochondral unit are therefore needed, with the hope that this will lead to curative, and not merely palliative, treatment options. The purpose of this narrative review is to investigate the role of the osteochondral unit in joint health and disease. Topics of discussion include the crosstalk between cartilage and bone, the efficacy of diagnostic procedures, the origins of joint pain, current and emerging treatment paradigms, and suitable preclinical animal models for safety and efficacy assessment of novel osteochondral therapies. The goal of the review is to facilitate an appreciation of the important role played by the subchondral bone in joint pain and why the osteochondral unit as a whole should be considered in many cases of joint restoration strategies.

Recombinant human FGF18 preserves depth-dependent mechanical inhomogeneity in articular cartilage

Articular cartilage is a specialised tissue that has a relatively homogenous endogenous cell population but a diverse extracellular matrix (ECM), with depth-dependent mechanical properties. Repair of this tissue remains an elusive clinical goal, with biological interventions preferred to arthroplasty in younger patients. Osteochondral transplantation (OCT) has emerged for the treatment of cartilage defects and osteoarthritis. Fresh allografts stored at 4 °C have been utilised, though matrix and cell viability loss remains an issue. To address this, several studies have developed media formulations to maintain cartilage explants in vitro. One promising factor for these applications is sprifermin, a human-recombinant fibroblast growth factor-18, which stimulates chondrocyte proliferation and matrix synthesis and is in clinical trials for the treatment of osteoarthritis. The study hypothesis was that addition of sprifermin during storage would maintain the unique depth-dependent mechanical profile of articular cartilage explants, a feature not often evaluated. Explants were maintained for up to 6 weeks with or without a weekly 24 h exposure to sprifermin (100 ng/mL) and the compressive modulus was assessed. Results showed that sprifermin-treated samples maintained their depth-dependent mechanical profile through 3 weeks, whereas untreated samples lost their mechanical integrity over 1 week of culture. Sprifermin also affected ECM balance by maintaining the levels of extracellular collagen and suppressing matrix metalloproteinase production. These findings support the use of sprifermin as a medium additive for OCT allografts during in vitro storage and present a potential mechanism where sprifermin may impact a functional characteristic of articular cartilage in repair strategies.

Patient-Specific Surgical Guidance System for Intelligent Orthopaedics

Clinical benefits for image-guided orthopaedic surgical systems are often measured in improved accuracy and precision of tool trajectories, prosthesis component positions and/or reduction of revision rate. However, with an ever-increasing demand for orthopaedic procedures, especially joint replacements, the ability to increase the number of surgeries, as well as lowering the costs per surgery, is generating a similar interest in the evaluation of image-guided orthopaedic systems. Patient-specific instrument guidance has recently gained popularity in various orthopaedic applications. Studies have shown that these guides are comparable to traditional image-guided systems with respect to accuracy and precision of the navigation of tool trajectories and/or prosthesis component positioning. Additionally, reports have shown that these single-use instruments also improve operating room management and reduce surgical time and costs. In this chapter, we discuss how patient-specific instrument guidance provides benefits to patients as well as to the health-care community for various orthopaedic applications.