Autologous chondrocyte implantation versus matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee

Rates and predictors of reimplantation of matrix-induced autologous chondrocyte implantation following first stage cartilage harvest: A cohort study

PURPOSE

To assess the reimplantation rate and predictors of patients requiring second-staged matrix-induced autologous chondrocyte implantation (MACI) reimplantation after initial first stage cartilage biopsy.

METHODS

A retrospective review was performed from 2018 to 2022 among patients who underwent only phase I MACI biopsy procedure (biopsy group) or both phase I with transition to phase II implantation of chondrocytes (implantation group) at a single tertiary center. Demographic, qualitative, and quantitative measurements were recorded, and univariate and multivariate regression analysis was performed to assess predictors of ultimately requiring second stage MACI implantation.

RESULTS

A total of 71 patients (51% female, age 27.7 ± 10.6 years (range 12-50)) were included in this study. Eventually, 25 of 71 patients (35.2%) experienced persistence of symptoms after initial MACI biopsy and other concomitant procedures, requiring second-stage implantation. Univariate analysis showed the implantation group compared to the biopsy group had a greater lesion size (5.2 cm2 ± 3.3 vs. 3.3 cm2 ± 1.4, p = 0.024), a higher proportion patients ≥ 26 years of age (76% vs. 43%, p = 0.009), a medial femoral condyle lesion more commonly (33% vs 11%, p = 0.005), were more often female (72% vs. 39%, p = 0.008), and had less often soft tissue repair at time of biopsy (32% vs. 61%, p = 0.020). Backward multivariate logistic regression analysis revealed that size of the lesion (OR 1.43, p = 0.031) and age ≥ 26 years old at time of biopsy (OR 3.55, p = 0.042) were independent predictors of not responding to initial surgery and requiring implantation surgery.

CONCLUSION

This study found that 35% of patients undergoing MACI phase I biopsy harvest eventually required autologous implantation. Independent risk factors for progressing to implantation after failed initial surgery were larger defect size and older age.

LEVEL OF EVIDENCE

III, Cohort Study.

Does progress in microfracture techniques necessarily translate into clinical effectiveness?

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Minimum 10-Year Outcomes of Matrix-Induced Autologous Chondrocyte Implantation in the Knee: A Systematic Review

BACKGROUND

Matrix-induced autologous chondrocyte implantation (MACI) is an established cell-based therapy for the treatment of chondral defects of the knee. As long-term outcomes are now being reported in the literature, it is important to systematically review available evidence to better inform clinical practice.

PURPOSE

To report (1) subjective patient-reported outcomes (PROs) and (2) the rate of graft failure, reoperation, and progression to total knee arthroplasty (TKA) after undergoing MACI of the knee at a minimum 10-year follow-up.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A comprehensive search of Ovid MEDLINE and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily; Ovid Embase; Ovid Cochrane Central Register of Controlled Trials; Ovid Cochrane Database of Systematic Reviews; and Scopus from 2008 to September 15, 2022, was conducted in the English language. Study eligibility criteria included (1) full-text articles in the English language, (2) patients undergoing a MACI within the knee, (3) clinical outcomes reported, and (4) a minimum 10-year follow-up.

RESULTS

In total, 168 patients (99 male, 69 female; mean age, 37 years [range, 15-63 years]; mean body mass index, 26.2 [range, 18.6-39.4]) representing 188 treated chondral defects at a minimum 10-year follow-up after MACI were included in this review. Significant and durable long-term improvements were observed across multiple PRO measures. Follow-up magnetic resonance imaging (MRI), when performed, also demonstrated satisfactory defect fill and an intact graft in the majority of patients. The all-cause reoperation rate was 9.0%, with an overall 7.4% rate of progression to TKA at 10 to 17 years of follow-up.

CONCLUSION

At a minimum 10-year follow-up, patients undergoing MACI for knee chondral defects demonstrated significant and durable improvements in PROs, satisfactory defect fill on MRI-based assessment, and low rates of reoperation and TKA. These data support the use of MACI as a long-term treatment of focal cartilage defects of the knee.

Sex-specific preservation of neuromuscular function and metabolism following systemic transplantation of multipotent adult stem cells in a murine model of progeria

Onset and rates of sarcopenia, a disease characterized by a loss of muscle mass and function with age, vary greatly between sexes. Currently, no clinical interventions successfully arrest age-related muscle impairments since the decline is frequently multifactorial. Previously, we found that systemic transplantation of our unique adult multipotent muscle-derived stem/progenitor cells (MDSPCs) isolated from young mice-but not old-extends the health-span in DNA damage mouse models of progeria, a disease of accelerated aging. Additionally, induced neovascularization in the muscles and brain-where no transplanted cells were detected-strongly suggests a systemic therapeutic mechanism, possibly activated through circulating secreted factors. Herein, we used ZMPSTE24-deficient mice, a lamin A defect progeria model, to investigate the ability of young MDSPCs to preserve neuromuscular tissue structure and function. We show that progeroid ZMPST24-deficient mice faithfully exhibit sarcopenia and age-related metabolic dysfunction. However, systemic transplantation of young MDSPCs into ZMPSTE24-deficient progeroid mice sustained healthy function and histopathology of muscular tissues throughout their 6-month life span in a sex-specific manner. Indeed, female-but not male-mice systemically transplanted with young MDSPCs demonstrated significant preservation of muscle endurance, muscle fiber size, mitochondrial respirometry, and neuromuscular junction morphometrics. These novel findings strongly suggest that young MDSPCs modulate the systemic environment of aged animals by secreted rejuvenating factors to maintain a healthy homeostasis in a sex-specific manner and that the female muscle microenvironment remains responsive to exogenous regenerative cues in older age. This work highlights the age- and sex-related differences in neuromuscular tissue degeneration and the future prospect of preserving health in older adults with systemic regenerative treatments.

Osteochondral Regeneration in the Knee Joint with Autologous Peripheral Blood Stem Cells plus Hyaluronic Acid after Arthroscopic Subchondral Drilling: Report of Five Cases

BACKGROUND

Treatment of osteochondral defects (OCDs) of the knee joint remains challenging. The purpose of this study was to evaluate the clinical and radiological results of osteochondral regeneration following intra-articular injections of autologous peripheral blood stem cells (PBSC) plus hyaluronic acid (HA) after arthroscopic subchondral drilling into OCDs of the knee joint.

CASE PRESENTATION

Five patients with OCDs of the knee joint are presented. The etiology includes osteochondritis dissecans, traumatic knee injuries, previously failed cartilage repair procedures involving microfractures and OATS (osteochondral allograft transfer systems). PBSC were harvested 1 week after surgery. Patients received intra-articular injections at week 1, 2, 3, 4, and 5 after surgery. Then at 6 months after surgery, intra-articular injections were administered at a weekly interval for 3 consecutive weeks. These 3 weekly injections were repeated at 12, 18 and 24 months after surgery. Each patient received a total of 17 injections. Subjective International Knee Documentation Committee (IKDC) scores and MRI scans were obtained preoperatively and postoperatively at serial visits. At follow-ups of >5 years, the mean preoperative and postoperative IKDC scores were 47.2 and 80.7 respectively (p = 0.005). IKDC scores for all patients exceeded the minimal clinically important difference values of 8.3, indicating clinical significance. Serial MRI scans charted the repair and regeneration of the OCDs with evidence of bone growth filling-in the base of the defects, followed by reformation of the subchondral bone plate and regeneration of the overlying articular cartilage.

CONCLUSION

These case studies showed that this treatment is able to repair and regenerate both the osseous and articular cartilage components of knee OCDs.

Ovine Mesenchymal Stem Cell Chondrogenesis on a Novel 3D-Printed Hybrid Scaffold In Vitro

This study evaluated the use of silica/poly(tetrahydrofuran)/poly(ε-caprolactone) (SiO2/PTHF/PCL-diCOOH) 3D-printed scaffolds, with channel sizes of either 200 (SC-200) or 500 (SC-500) µm, as biomaterials to support the chondrogenesis of sheep bone marrow stem cells (oBMSC), under in vitro conditions. The objective was to validate the potential use of SiO2/PTHF/PCL-diCOOH for prospective in vivo ovine studies. The behaviour of oBMSC, with and without the use of exogenous growth factors, on SiO2/PTHF/PCL-diCOOH scaffolds was investigated by analysing cell attachment, viability, proliferation, morphology, expression of chondrogenic genes (RT-qPCR), deposition of aggrecan, collagen II, and collagen I (immunohistochemistry), and quantification of sulphated glycosaminoglycans (GAGs). The results showed that all the scaffolds supported cell attachment and proliferation with upregulation of chondrogenic markers and the deposition of a cartilage extracellular matrix (collagen II and aggrecan). Notably, SC-200 showed superior performance in terms of cartilage gene expression. These findings demonstrated that SiO2/PTHF/PCL-diCOOH with 200 µm pore size are optimal for promoting chondrogenic differentiation of oBMSC, even without the use of growth factors.

Photo-Cross-Linkable, Injectable, and Highly Adhesive GelMA-Glycol Chitosan Hydrogels for Cartilage Repair

Hydrogels provide a promising platform for cartilage repair and regeneration. Although hydrogels have shown some efficacy, they still have shortcomings including poor mechanical properties and suboptimal integration with surrounding cartilage. Herein, hydrogels that are injectable, cytocompatible, mechanically robust, and highly adhesive to cartilage are developed. This approach uses GelMA-glycol chitosan (GelMA-GC) that is crosslinkable with visible light and photoinitiators (lithium acylphosphinate and tris (2,2'-bipyridyl) dichlororuthenium (II) hexahydrate ([RuII(bpy)3 ]2+ and sodium persulfate (Ru/SPS)). Ru/SPS-cross-linked hydrogels have higher compressive and tensile modulus, and most prominently higher adhesive strength with cartilage, which also depends on inclusion of GC. Tensile and push-out tests of the Ru/SPS-cross-linked GelMA-GC hydrogels demonstrate adhesive strength of ≈100 and 46 kPa, respectively. Hydrogel precursor solutions behave in a Newtonian manner and are injectable. After injection in focal bovine cartilage defects and in situ cross-linking, this hydrogel system remains intact and integrated with cartilage following joint manipulation ex vivo. Cells remain viable (>85%) in the hydrogel system and further show tissue regeneration potential after three weeks of in vitro culture. These preliminary results provide further motivation for future research on bioadhesive hydrogels for cartilage repair and regeneration.

The AMADEUS score is not a sufficient predictor for functional outcome after autologous chondrocyte implantation (ACI) of the knee: data from the German Cartilage Registry (KnorpelRegister DGOU)

INTRODUCTION

The AMADEUS (Area Measurement And DEpth and Underlying Structures) score has advanced to a commonly used tool for MRI-based chondral defect severity grading prior to cartilage knee surgery. It was the intention of this study to assess the AMADEUS for a potential correlation with clinical data by patient-reported outcome measures (PROMs).

METHODS

A total of 51 patients undergoing ACI (autologous chondrocyte implantation) between 2016 and 2022 were found eligible and retrospectively analyzed. All patients were registered in the German Cartilage Registry prior to surgery and follow-up data were collected using the Knee Osteoarthritis Outcome score (KOOS), the International Knee Documentation Committee (IKDC) Form and the numeric rating scale (NRS). Pre-operative MRI images were scored by three raters using the AMADEUS classification system, and an overall AMADEUS score was calculated which was subsequently correlated with pre- and post-operative PROMs.

RESULTS

Mean patient age was 32.67 ± 8.37 years and mean defect size area 343.04 mm2 ± 139.45 mm2. No correlative capacity of the pre- and postoperative IKDC, KOOS or NRS scores was found with the AMADEUS final score or any of its subscores. From the pre- to postoperative visit, a significant improvement of the PROMs (IKDC: 45.53 ± 21.00 vs. 59.83 ± 17.93, p = 0.04; KOOS Pain: 58.00 ± 16.70 vs. 76.06 ± 19.20, p = 0.03; KOOS ADL: 64.17 ± 18.76 vs. 82.11 ± 16.68, p < 0.01; KOOS Sports: 26.11 ± 18.52 vs. 50.56 ± 23.94, p = 0.01; KOOS QOL: 25.50 ± 14.26 ± 45.28 ± 19.03, p = 0.00) was found. Intraclass correlation coefficients showed an overall good interrater agreement for the AMADEUS total score (ICC = 0.75).

CONCLUSIONS

Study results suggest no correlative capacity of the AMADEUS with routinely used PROMs in patients undergoing ACI. Therefore, radiographically assessed cartilage defect characteristics poorly translate to pre- and postoperative patient-reported outcome data.

Applications of Bacterial Cellulose-Based Composite Materials in Hard Tissue Regenerative Medicine

BACKGROUND

Cartilage, bone, and teeth, as the three primary hard tissues in the human body, have a significant application value in maintaining physical and mental health. Since the development of bacterial cellulose-based composite materials with excellent biomechanical strength and good biocompatibility, bacterial cellulose-based composites have been widely studied in hard tissue regenerative medicine. This paper provides an overview of the advantages of bacterial cellulose-based for hard tissue regeneration and reviews the recent progress in the preparation and research of bacterial cellulose-based composites in maxillofacial cartilage, dentistry, and bone.

METHOD

A systematic review was performed by searching the PubMed and Web of Science databases using selected keywords and Medical Subject Headings search terms.

RESULTS

Ideal hard tissue regenerative medicine materials should be biocompatible, biodegradable, non-toxic, easy to use, and not burdensome to the human body; In addition, they should have good plasticity and processability and can be prepared into materials of different shapes; In addition, it should have good biological activity, promoting cell proliferation and regeneration. Bacterial cellulose materials have corresponding advantages and disadvantages due to their inherent properties. However, after being combined with other materials (natural/ synthetic materials) to form composite materials, they basically meet the requirements of hard tissue regenerative medicine materials. We believe that it is worth being widely promoted in clinical applications in the future.

CONCLUSION

Bacterial cellulose-based composites hold great promise for clinical applications in hard tissue engineering. However, there are still several challenges that need to be addressed. Further research is needed to incorporate multiple disciplines and advance biological tissue engineering techniques. By enhancing the adhesion of materials to osteoblasts, providing cell stress stimulation through materials, and introducing controlled release systems into matrix materials, the practical application of bacterial cellulose-based composites in clinical settings will become more feasible in the near future.

Ultrasound-Driven Healing: Unleashing the Potential of Chondrocyte-Derived Extracellular Vesicles for Chondrogenesis in Adipose-Derived Stem Cells

Repairing cartilage defects represents a significant clinical challenge. While adipose-derived stem cell (ADSC)-based strategies hold promise for cartilage regeneration, their inherent chondrogenic potential is limited. Extracellular vesicles (EVs) derived from chondrocytes (CC-EVs) have shown potential in enhancing chondrogenesis, but their role in promoting chondrogenic differentiation of ADSCs remains poorly understood. Moreover, the clinical application of EVs faces limitations due to insufficient quantities for in vivo use, necessitating the development of effective methods for extracting significant amounts of CC-EVs. Our previous study demonstrated that low-intensity ultrasound (LIUS) stimulation enhances EV secretion from mesenchymal stem cells. Here, we identified a specific LIUS parameter for chondrocytes that increased EV secretion by 16-fold. CC-EVs were found to enhance cell activity, proliferation, migration, and 21-day chondrogenic differentiation of ADSCs in vitro, while EVs secreted by chondrocytes following LIUS stimulation (US-CC-EVs) exhibited superior efficacy. miRNA-seq revealed that US-CC-EVs were enriched in cartilage-regeneration-related miRNAs, contributing to chondrogenesis in various biological processes. In conclusion, we found that CC-EVs can enhance the chondrogenesis of ADSCs in vitro. In addition, our study introduces ultrasound-driven healing as an innovative method to enhance the quantity and quality of CC-EVs, meeting clinical demand and addressing the limited chondrogenic potential of ADSCs. The ultrasound-driven healing unleashes the potential of CC-EVs for chondrogenesis possibly through the enrichment of cartilage-regeneration-associated miRNAs in EVs, suggesting their potential role in cartilage reconstruction. These findings hold promise for advancing cartilage regeneration strategies and may pave the way for novel therapeutic interventions in regenerative medicine.

Knee Cartilage Lesion Management-Current Trends in Clinical Practice

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

Radiographic Evidence of Early Posttraumatic Osteoarthritis following Tibial Plateau Fracture Is Associated with Poorer Function

To determine if radiographic evidence of posttraumatic osteoarthritis (PTOA) following tibial plateau fracture correlates with poorer clinical and functional outcomes, patients with tibial plateau fractures were followed at 3, 6, and 12 months. All patients had baseline radiographs and computed tomography scan. Radiographs obtained at each follow-up were reviewed for healing, articular incongruence, hardware positional changes, and the development of postinjury arthritic change. Cohorts were determined based on the presence (PTOA) or absence (NPTOA) of radiographic evidence of PTOA. Demographics, fracture classification, complications, additional procedures, and functional status were compared between cohorts. Sixty patients had radiographic evidence of PTOA on follow-up radiographs at a mean final follow-up of 24.2 months. The NPTOA cohort was composed of 210 patients who were matched to the PTOA cohort based on age and Charlson comorbidity index. Mean time to fracture union for the overall cohort was 4.86 months. Cohorts did not differ in Schatzker classification, time to healing, injury mechanism, or baseline Short Musculoskeletal Function Assessment (SMFA). Patients with PTOA had a greater degree of initial depression and postoperative step-off, higher incidence of initial external fixator usage, higher rates of reoperation for any reason, and higher rates of wound complications. Associated soft tissue injury and meniscal repair did not coincide with the development of PTOA. Range of motion and SMFA scores were significantly worse at all time points in patients with PTOA. Although fracture patterns are similar, patients who required an initial external fixator, had a greater degree of initial depression or residual articular incongruity, underwent more procedures, and developed an infection were found to have increased incidence of PTOA. Radiographic evidence of osteoarthritis correlated with worse functional status in patients. The goal of surgery should be restoration of articular congruity and stability to mitigate the risk of PTOA, although this alone may not prevent degenerative changes. Patients with early loss of range of motion should be aggressively treated as this may precede the development of PTOA.

Cartilage Tissue Engineering in Practice: Preclinical Trials, Clinical Applications, and Prospects

Articular cartilage defects significantly compromise the quality of life in the global population. Although many strategies are needed to repair articular cartilage, including microfracture, autologous osteochondral transplantation, and osteochondral allograft, the therapeutic effects remain suboptimal. In recent years, with the development of cartilage tissue engineering, scientists have continuously improved the formulations of therapeutic cells, biomaterial-based scaffolds, and biological factors, which have opened new avenues for better therapeutics of cartilage lesions. This review focuses on advances in cartilage tissue engineering, particularly in preclinical trials and clinical applications, prospects, and challenges.

Bio-Inspired Nanomaterials for Micro/Nanodevices: A New Era in Biomedical Applications

Exploring bio-inspired nanomaterials (BINMs) and incorporating them into micro/nanodevices represent a significant development in biomedical applications. Nanomaterials, engineered to imitate biological structures and processes, exhibit distinctive attributes such as exceptional biocompatibility, multifunctionality, and unparalleled versatility. The utilization of BINMs demonstrates significant potential in diverse domains of biomedical micro/nanodevices, encompassing biosensors, targeted drug delivery systems, and advanced tissue engineering constructs. This article thoroughly examines the development and distinctive attributes of various BINMs, including those originating from proteins, DNA, and biomimetic polymers. Significant attention is directed toward incorporating these entities into micro/nanodevices and the subsequent biomedical ramifications that arise. This review explores biomimicry's structure-function correlations. Synthesis mosaics include bioprocesses, biomolecules, and natural structures. These nanomaterials' interfaces use biomimetic functionalization and geometric adaptations, transforming drug delivery, nanobiosensing, bio-inspired organ-on-chip systems, cancer-on-chip models, wound healing dressing mats, and antimicrobial surfaces. It provides an in-depth analysis of the existing challenges and proposes prospective strategies to improve the efficiency, performance, and reliability of these devices. Furthermore, this study offers a forward-thinking viewpoint highlighting potential avenues for future exploration and advancement. The objective is to effectively utilize and maximize the application of BINMs in the progression of biomedical micro/nanodevices, thereby propelling this rapidly developing field toward its promising future.

Surgical Management of Failed Articular Cartilage Surgery in the Knee

Failure rates of cartilage restoration surgery range from 14% to 43%. When failure of prior cartilage restoration surgery is suspected, a thorough clinical workup should be performed to assess the timing and duration of symptoms. Attention should be paid to patient risk factors such as age, body mass index, and smoking status. Concomitant pathology such as malalignment, ligament insufficiency, and meniscus status must be evaluated before revision surgery. As outlined in our treatment algorithm, the size/location of the lesion and the type of primary procedure will guide planning for revision procedures. [Orthopedics. 2023;46(5):262-272.].

Single-step ultra-purified alginate gel implantation in patients with knee chondral defects

Aims

Implantation of ultra-purified alginate (UPAL) gel is safe and effective in animal osteochondral defect models. This study aimed to examine the applicability of UPAL gel implantation to acellular therapy in humans with cartilage injury.

Methods

A total of 12 patients (12 knees) with symptomatic, post-traumatic, full-thickness cartilage lesions (1.0 to 4.0 cm²) were included in this study. UPAL gel was implanted into chondral defects after performing bone marrow stimulation technique, and assessed for up to three years postoperatively. The primary outcomes were the feasibility and safety of the procedure. The secondary outcomes were self-assessed clinical scores, arthroscopic scores, tissue biopsies, and MRI-based estimations.

Results

No obvious adverse events related to UPAL gel implantation were observed. Self-assessed clinical scores, including pain, symptoms, activities of daily living, sports activity, and quality of life, were improved significantly at three years after surgery. Defect filling was confirmed using second-look arthroscopy at 72 weeks. Significantly improved MRI scores were observed from 12 to 144 weeks postoperatively. Histological examination of biopsy specimens obtained at 72 weeks after implantation revealed an extracellular matrix rich in glycosaminoglycan and type II collagen in the reparative tissue. Histological assessment yielded a mean overall International Cartilage Regeneration & Joint Preservation Society II score of 69.1 points (SD 10.4; 50 to 80).

Conclusion

This study provides evidence supporting the safety of acellular UPAL gel implantation in facilitating cartilage repair. Despite being a single-arm study, it demonstrated the efficacy of UPAL gel implantation, suggesting it is an easy-to-use, one-step method of cartilage tissue repair circumventing the need to harvest donor cells.

Comparison of Hydrogel-Based Autologous Chondrocyte Implantation Versus Microfracture: A Propensity Score Matched-Pair Analysis

Background

Few studies exist for large defects comparing matrix-associated autologous chondrocyte implantation (M-ACI) with other cartilage repair methods due to the limited availability of suitable comparator treatments.

Purpose

To compare the clinical efficacy of a novel hydrogel-based M-ACI method (NOVOCART Inject plus) versus microfracture (MFx) in patients with knee cartilage defects.

Study Design

Cohort study; Level of evidence, 3.

Methods

Propensity score matched-pair analysis was used to compare the 24-month outcomes between the M-ACI treatment group from a previous single-arm phase 3 study and the MFx control group from another phase 3 study. Patients were matched based on preoperative Knee injury and Osteoarthritis Outcomes Score (KOOS), symptom duration, previous knee surgeries, age, and sex, resulting in 144 patients in the matched-pair set (72 patients per group). The primary endpoint was the change in least-squares means (ΔLSmeans) for the KOOS from baseline to the 24-month assessment.

Results

Defect sizes in the M-ACI group were significantly larger than in the MFx group (6.4 versus 3.7 cm2). Other differences included defect location (no patellar or tibial defects in the MFx group), number of defects (33.3% with 2 defects in the M-ACI group versus 9.7% in the MFx group), and defect cause (more patients with degenerative lesions in the M-ACI group). The M-ACI group had higher posttreatment KOOS (M-ACI versus MFX: 81.8 ± 16.8 versus 73.0 ± 20.6 points) and KOOS ΔLSmeans from baseline to 24 months posttreatment (M-ACI versus MFX: 36.9 versus 26.9 points). Treatment contrasts in KOOS ΔLSmeans from baseline indicated statistical significance in favor of M-ACI from 3 to 24 months posttreatment (P = .0026). Significant and clinically meaningful differences in favor of M-ACI at 24 months were also found regarding International Knee Documentation Committee (IKDC) score ΔLSmeans from baseline (37.8 versus 30.4 points; P = .0334), KOOS responder rates at 24 months (≥10-point improvement from baseline; 94.4% versus 65.3%; P < .0001), IKDC responder rates at 24 months (>20.5-point improvement from baseline; 83.3% versus 61.1%, P = .0126) and MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score in a subgroup of patients (LS means, 86.9 versus 69.1; P = .0096).

Conclusion

In this exploratory analysis, M-ACI using an in situ crosslinked hydrogel demonstrated superior clinical and structural (MOCART) 24-month outcomes compared with MFx in patients with knee cartilage defects.

Scaffolds containing GAG-mimetic cellulose sulfate promote TGF-β interaction and MSC Chondrogenesis over native GAGs

Cartilage tissue engineering strategies seek to repair damaged tissue using approaches that include scaffolds containing components of the native extracellular matrix (ECM). Articular cartilage consists of glycosaminoglycans (GAGs) which are known to sequester growth factors. In order to more closely mimic the native ECM, this study evaluated the chondrogenic differentiation of mesenchymal stem cells (MSCs), a promising cell source for cartilage regeneration, on fibrous scaffolds that contained the GAG-mimetic cellulose sulfate. The degree of sulfation was evaluated, examining partially sulfated cellulose (pSC) and fully sulfated cellulose (NaCS). Comparisons were made with scaffolds containing native GAGs (chondroitin sulfate A, chondroitin sulfate C and heparin). Transforming growth factor-beta3 (TGF-β3) sequestration, as measured by rate of association, was higher for sulfated cellulose-containing scaffolds as compared to native GAGs. In addition, TGF-β3 sequestration and retention over time was highest for NaCS-containing scaffolds. Sulfated cellulose-containing scaffolds loaded with TGF-β3 showed enhanced chondrogenesis as indicated by a higher Collagen Type II:I ratio over native GAGs. NaCS-containing scaffolds loaded with TGF-β3 had the highest expression of chondrogenic markers and a reduction of hypertrophic markers in dynamic loading conditions, which more closely mimic in vivo conditions. Studies also demonstrated that TGF-β3 mediated its effect through the Smad2/3 signaling pathway where the specificity of TGF-β receptor (TGF- βRI)-phosphorylated SMAD2/3 was verified with a receptor inhibitor. Therefore, studies demonstrate that scaffolds containing cellulose sulfate enhance TGF-β3-induced MSC chondrogenic differentiation and show promise for promoting cartilage tissue regeneration.

The Influence of Arthroscopic Shaver Mincing and Platelet-Rich Plasma on Chondrocytes of Intraoperatively Harvested Human Cartilage

BACKGROUND

Minced cartilage implantation (MCI) has seen a renaissance in recent years. In this evolved technique, human articular cartilage is harvested with an arthroscopic shaver, augmented with platelet-rich plasma (PRP), and implanted with autologous thrombin. This modified technique combines the possibility of cell-based surgical cartilage repair with a minimally invasive autologous 1-step procedure. However, evidence on cell survival and preserved function after shaver-based mincing and PRP supplementation is limited.

PURPOSE

To evaluate the effects of arthroscopic shaver mincing and augmentation with PRP on human cartilage tissue.

STUDY DESIGN

Controlled laboratory study.

METHODS

Standardized samples were taken from 12 donors during autologous MCI. A comparison of cell outgrowth, cell viability, proliferation capacity, and ability to produce extracellular matrix-specific proteoglycans after chondrogenic redifferentiation was made between cartilage taken by curettage from the border of the cartilage defect, cartilage tissue minced by an arthroscopic shaver, and cartilage tissue minced by an arthroscopic shaver that was additionally augmented with autologous PRP.

RESULTS

There was no difference between all 3 groups in terms of cell outgrowth or proliferation capacity. Metabolic activity relative to the cell number of chondrocytes isolated from shaver-minced cartilage was higher compared with chondrocytes isolated from cartilage that was derived by curettage or shaver-minced cartilage that was augmented with PRP. After chondrogenic stimulation, the normalized proteoglycan content was higher in spheroids of cells derived from shaver-minced cartilage augmented with PRP than in spheroids of cells derived from curettage. A high correlation of cell outgrowth, proliferation capacity, and viability between isolated cells from all 3 groups taken from an individual donor was observed.

CONCLUSION

Chondrocytes isolated from human cartilage tissue that was harvested and minced with an arthroscopic shaver remained viable and proliferative. The augmentation of shaver-minced cartilage with PRP led to the enhanced proteoglycan production of chondrogenic spheroids in vitro, pointing toward the development of a cartilage-specific extracellular matrix. This in vitro study yields promising results regarding the use of an arthroscopic shaver and augmentation with PRP in the context of MCI.

CLINICAL RELEVANCE

Knowledge that shaver mincing and augmentation with PRP are feasible for processing articular cartilage during MCI is highly relevant for surgical cartilage repair.

Elastomeric Porous Poly(glycerol sebacate) Methacrylate (PGSm) Microspheres as 3D Scaffolds for Chondrocyte Culture and Cartilage Tissue Engineering

Cartilage defects can be difficult to treat; therefore, tissue engineering of cartilage is emerging as a promising potential therapy. One interesting area of research explores the delivery of cells to the cartilage defect via scaffold-based cell delivery vehicles and microsurgery. This study explores the use of novel poly(glycerol sebacate) methacrylate (PGSm)-polymerised high internal phase emulsion (polyHIPE) microspheres as scaffolds with embedded cells for cartilage tissue engineering. Porous microsphere scaffolds (100 µm-1 mm diameter) were produced from emulsions consisting of water and a methacrylate-based photocurable resin of poly(glycerol sebacate). These resins were used in conjunction with a T-junction fluidic device and an ultraviolet (UV) curing lamp to produce porous microspheres with a tuneable size. This technique produced biodegradable PGSm microspheres with similar mechanical properties to cartilage. We further explore these microspheres as scaffolds for three-dimensional culture of chondrocytes. The microspheres proved to be very efficient scaffolds for primary chondrocyte culture and were covered by a dense extracellular matrix (ECM) network during the culture period, creating a tissue disk. The presence of glycosaminoglycans (GAGs) and collagen-II was confirmed, highlighting the utility of the PGSm microspheres as a delivery vehicle for chondrocytes. A number of imaging techniques were utilised to analyse the tissue disk and develop methodologies to characterise the resultant tissue. This study highlights the utility of porous PGSm microspheres for cartilage tissue engineering.

Neo-cartilage formation using human nondegenerate versus osteoarthritic chondrocyte-derived cartilage organoids in a viscoelastic hydrogel

Current regenerative cartilage therapies are associated with several drawbacks such as dedifferentiation of chondrocytes during expansion and the formation of fibrocartilage. Optimized chondrocyte expansion and tissue formation could lead to better clinical results of these therapies. In this study, a novel chondrocyte suspension expansion protocol that includes the addition of porcine notochordal cell-derived matrix was used to self-assemble human chondrocytes from osteoarthritic (OA) and nondegenerate (ND) origin into cartilage organoids containing collagen type II and proteoglycans. Proliferation rate and viability were similar for OA and ND chondrocytes and organoids formed had a similar histologic appearance and gene expression profile. Organoids were then encapsulated in viscoelastic alginate hydrogels to form larger tissues. Chondrocytes on the outer bounds of the organoids produced a proteoglycan-rich matrix to bridge the space between organoids. In hydrogels containing ND organoids some collagen type I was observed between the organoids. Surrounding the bulk of organoids in the center of the gels, in both OA and ND gels a continuous tissue containing cells, proteoglycans and collagen type II had been produced. No difference was observed in sulphated glycosaminoglycan and hydroxyproline content between gels containing organoids from OA or ND origin after 28 days. It was concluded that OA chondrocytes, which can be harvested from leftover surgery tissue, perform similar to ND chondrocytes in terms of human cartilage organoid formation and matrix production in alginate gels. This opens possibilities for their potential to serve as a platform for cartilage regeneration but also as an in vitro model to study pathways, pathology, or drug development.

The Large Focal Isolated Chondral Lesion

Focal chondral defects (FCDs) of the knee can be a debilitating condition that can clinically translate into pain and dysfunction in young patients with high activity demands. Both the understanding of the etiology of FCDs and the surgical management of these chondral defects has exponentially grown in recent years. This is reflected by the number of surgical procedures performed for FCDs, which is now approximately 200,000 annually. This fact is also apparent in the wide variety of available surgical approaches to FCDs. Although simple arthroscopic debridement or microfracture are usually the first line of treatment for smaller lesions, chondral lesions that involve a larger area or depth require restorative procedures such as osteochondral allograft transplantation or other cell-based techniques. Given the prevalence of FCDs and the increased attention on treating these lesions, a comprehensive understanding of management from diagnosis to rehabilitation is imperative for the treating surgeon. This narrative review aims to describe current concepts in the treatment of large FCDs through providing an algorithmic approach to selecting interventions to address these lesions as well as the reported outcomes in the literature.

Surgical strategies for chondral defects of the patellofemoral joint: a systematic review

BACKGROUND

The management of chondral defects of the patellofemoral joint is debated, and definitive evidence is lacking. This study systematically updated and summarised the current literature on the surgical management of isolated chondral defects of the patellofemoral joint, discussing techniques, outcome, pitfalls, and new frontiers.

METHODS

This systematic review was conducted according to the 2020 PRISMA statement. In August 2022, PubMed, Web of Science, Google Scholar, and Embase databases were accessed with no time constrain. All the clinical studies investigating the surgical management of chondral defects of the patellofemoral joint were retrieved. Articles which reported data on patients with advanced to severe osteoarthritis were not eligible. Only studies with a minimum 24 months follow-up were considered. Studies which mixed results of patellofemoral and tibiofemoral joints were not considered.

RESULTS

Data from 10 studies (692 procedures) were retrieved. The mean follow-up was 46.9 ± 18.2 months. The mean age of the patients was 34.0 ± 6.1 years, and the mean BMI was 25.9 ± 0.8 kg/m². The mean duration of symptoms before the index surgery was 81.0 ± 24.0 months. The mean defect size was 3.8 ± 0.8 cm². All the PROMs improved from baseline to last follow-up: VAS 0-10 (P = 0.04), Tegner (P = 0.02), Lysholm (P = 0.03), and International Knee Documentation Committee (P = 0.03). The rate of hypertrophy was 5.6% (14 of 251), the rate of progression to total knee arthroplasty was 2.4% (2 of 83), the rate of revision was 16.9% (29 of 136), and the rate of failure was 13.0% (16 of 123).

CONCLUSION

Current surgical strategies may be effective to improve symptoms deriving from chondral defects of the patellofemoral joint. The limited and heterogeneous data included for analysis impact negatively the results of the present study. Further clinical studies are strongly required to define surgical indications and outcomes, and the most suitable technique.

Adult Stem Cells for Cartilage Regeneration

As cartilage is an avascular, aneural structure, it has very low capabilities of self-repair. Osteoarthritis prevalence is increasing, and there are no clinically approved management techniques that can cure the degradation of cartilage. This report investigates the efficacy of different sources of cells to generate articular cartilage. Autologous chondrocyte implantation has been used to some extent in clinics; however it has not generated efficient, reliable results, and there is no evidence of long-term success. The usage of stem cells is more promising, particularly mesenchymal stem cells (MSCs). Human embryonic stem cells (hESCs) have also been trialed; however, it is important to note that the process of differentiation into chondrocytes is not fully understood, and the cartilage produced can often be of poor quality. MSCs seems to be the way forward, and hESCs will perhaps need further study with the usage of MSC differentiation methodology.

Talar Dome Osteochondral Lesions: Pre- and Postoperative Imaging

We suggest a similar approach to evaluating osteochondral lesions of the talar dome both pre- and postoperatively. This review addresses the etiology, natural history, and treatment of talar dome osteochondral lesions with an emphasis on imaging appearances. High-resolution magnetic resonance imaging, ideally combining a small field-of-view surface coil with ankle traction, optimizes visibility of most of the clinically relevant features both pre- and postoperatively.

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.

Fixation of the Membrane during Matrix-Induced Autologous Chondrocyte Implantation in the Knee: A Systematic Review

Introduction: It is unclear whether the type of membrane used for matrix-assisted autologous chondrocyte implantation (mACI) influences results. A systematic review was conducted to investigate the midterm results of the three most common types of membrane fixation for mACI. Methods: This systematic review was conducted according to the 2020 PRISMA checklist. PubMed, Google Scholar, Embase, and Scopus online databases were accessed in August 2022. All the prospective clinical trials reporting outcomes of mACI in the knee were considered. Studies that describe the modality of membrane fixation (glued, glued, and sutured, no fixation) used for mACI were eligible. Studies that conducted a minimum of 12 months of follow-up were considered. The outcomes of interest were the Tegner Activity Scale and International Knee Documentation Committee (IKDC) score. The rate of failure and revisions were also collected. Results: Data from 26 studies (1539 procedures; 554 of 1539 (36%) were women) were retrieved. The mean follow-up was 42.6 (12 to 84) months. No difference between the groups was found in terms of mean duration of symptoms, age, BMI, gender, and defect size (P > 0.1). No difference was found in terms of the Tegner score (P = 0.3). When no fixation was used, a statistically significant higher IKDC compared to the other groups (P = 0.02) was evidenced. No difference was found in the rate of failure (P = 0.1). The no-fixation group evidenced a statistically significant lower rate of revisions (P = 0.02). Conclusions: No membrane fixation for mACI in the knee scored better than the fastening techniques at the midterm follow-up.

Advances in Biomaterial-Mediated Gene Therapy for Articular Cartilage Repair

Articular cartilage defects caused by various reasons are relatively common in clinical practice, but the lack of efficient therapeutic methods remains a substantial challenge due to limitations in the chondrocytes’ repair abilities. In the search for scientific cartilage repair methods, gene therapy appears to be more effective and promising, especially with acellular biomaterial-assisted procedures. Biomaterial-mediated gene therapy has mainly been divided into non-viral vector and viral vector strategies, where the controlled delivery of gene vectors is contained using biocompatible materials. This review will introduce the common clinical methods of cartilage repair used, the strategies of gene therapy for cartilage injuries, and the latest progress.

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.

Synoviocyte-Derived Extracellular Matrix and bFGF Speed Human Chondrocyte Proliferation While Maintaining Differentiation Potential

Improving the ability of human chondrocytes to proliferate, while maintaining their differentiation potential, has presented a great challenge in cartilage tissue engineering. In this study, human chondrocytes were cultured under four unique growth conditions at physiologic oxygen tension: tissue culture plastic (TCP) only, synoviocyte matrix (SCM)-coated flasks only, SCM-coated flasks with bFGF media supplement, and TCP with bFGF media supplement. The results indicated that, compared to standard TCP, all test conditions showed significantly increased cell expansion rates and an increase in both glycosaminoglycan (GAG) and collagen content during redifferentiation culture. Specifically, the combined SCM + bFGF growth condition showed an additive effect, with an increase of approximately 36% more cells per passage (5-7 days) when compared to the SCM alone. In conclusion, the results of this study demonstrate that bFGF and SCM can be used as supplements to enhance the growth of human chondrocytes both as individual enhancers and as a combined additive.

Instructive cartilage regeneration modalities with advanced therapeutic implantations under abnormal conditions

The development of interdisciplinary biomedical engineering brings significant breakthroughs to the field of cartilage regeneration. However, cartilage defects are considerably more complicated in clinical conditions, especially when injuries occur at specific sites (e.g., osteochondral tissue, growth plate, and weight-bearing area) or under inflammatory microenvironments (e.g., osteoarthritis and rheumatoid arthritis). Therapeutic implantations, including advanced scaffolds, developed growth factors, and various cells alone or in combination currently used to treat cartilage lesions, address cartilage regeneration under abnormal conditions. This review summarizes the strategies for cartilage regeneration at particular sites and pathological microenvironment regulation and discusses the challenges and opportunities for clinical transformation.

Bilayered extracellular matrix derived scaffolds with anisotropic pore architecture guide tissue organization during osteochondral defect repair

While some clinical advances in cartilage repair have occurred, osteochondral (OC) defect repair remains a significant challenge, with current scaffold-based approaches failing to recapitulate the complex, hierarchical structure of native articular cartilage (AC). To address this need, we fabricated bilayered extracellular matrix (ECM)-derived scaffolds with aligned pore architectures. By modifying the freeze-drying kinetics and controlling the direction of heat transfer during freezing, it was possible to produce anisotropic scaffolds with larger pores which supported homogenous cellular infiltration and improved sulfated glycosaminoglycan deposition. Neo-tissue organization in vitro could also be controlled by altering scaffold pore architecture, with collagen fibres aligning parallel to the long-axis of the pores within scaffolds containing aligned pore networks. Furthermore, we used in vitro and in vivo assays to demonstrate that AC and bone ECM derived scaffolds could preferentially direct the differentiation of mesenchymal stromal cells (MSCs) towards either a chondrogenic or osteogenic lineage respectively, enabling the development of bilayered ECM scaffolds capable of spatially supporting unique tissue phenotypes. Finally, we implanted these scaffolds into a large animal model of OC defect repair. After 6 months in vivo, scaffold implantation was found to improve cartilage matrix deposition, with collagen fibres preferentially aligning parallel to the long axis of the scaffold pores, resulting in a repair tissue that structurally and compositionally was more hyaline-like in nature. These results demonstrate how scaffold architecture and composition can be spatially modulated to direct the regeneration of complex interfaces such as the osteochondral unit, enabling their use as cell-free, off-the-shelf implants for joint regeneration. STATEMENT OF SIGNIFICANCE: The architecture of the extracellular matrix, while integral to tissue function, is often neglected in the design and evaluation of regenerative biomaterials. In this study we developed a bilayered scaffold for osteochondral defect repair consisting of tissue-specific extracellular matrix (ECM)-derived biomaterials to spatially direct stem/progenitor cell differentiation, with a tailored pore microarchitecture to promote the development of a repair tissue that recapitulates the hierarchical structure of native AC. The use of this bilayered scaffold resulted in improved tissue repair outcomes in a large animal model, specifically the ability to guide neo-tissue organization and therefore recapitulate key aspects of the zonal structure of native articular cartilage. These bilayer scaffolds have the potential to become a new therapeutic option for osteochondral defect repair.

Editorial Commentary: No Clear Winner When Comparing Cost-Effectiveness of Particulated Juvenile Articular Cartilage With Matrix-Induced Autologous Chondrocyte Implantation: Too Many Assumptions

Various treatment options exist for patellar chondral lesions, including nonoperative management, marrow stimulation, cell-based strategies, and osteochondral transplantation, yet there is insufficient evidence to recommend one treatment over another. One frequently discussed downside of cell-based strategies, including particulated juvenile allograft cartilage and matrix-induced autologous chondrocyte implantation, is the associated cost. Markov modeling is a tool used for economic modeling of different treatments and may be a viable option to compare cell-based strategies for patellar chondral defects. Too many assumptions carry great risk of drawing a strong conclusion. Further high-quality studies and comparative outcome studies are needed before any definitive cost-effectiveness conclusion is made.

A phase I/IIa clinical trial of third-generation autologous chondrocyte implantation (IK-01) for focal cartilage injury of the knee

Background/objective

The purpose of this study was to report the outcomes of a clinical trial conducted in Japan to assess the safety and effectiveness of third-generation autologous chondrocyte implantation (ACI) using IK-01 (CaReS™), which does not require flap coverage, in the treatment of patients with focal cartilage injury of the knee.

Methods

This was an open label, exploratory clinical trial. Patients were enrolled between June 2012 and September 2016. The primary endpoint of the study was the International Knee Documentation Committee (IKDC) score at 52 weeks after implantation. The IKDC, Lysholm, and visual analog scale (VAS) scores were evaluated at the time of screening and at 4, 12, 24, 36, and 52 weeks after implantation. Improvements from the baseline scores were evaluated using the equation “(postoperative score) − (preoperative score).” Magnetic resonance imaging (MRI) was performed at 2, 12, 24, and 52 weeks after implantation, and MRI measurements were evaluated using T1 rho and T2 mapping.

Results

Nine patients were enrolled in this study and were examined for safety. Product quality did not satisfy the specification in one patient, and bacterial joint infection occurred in one patient. As a result, seven patients were included in the outcome analyses. The mean IKDC score significantly improved from 36.4 preoperatively to 74.1% at 52 weeks after implantation (p < 0.0001). The mean Lysholm and VAS scores also significantly improved from 39.6 to 57.4 to 89.6 and 22.9, respectively, after surgery. In the MRI evaluation, the T1 rho and T2 values of the implanted area were similar to those of the surrounding cartilage at 52 weeks after implantation.

Conclusions

Third generation ACI (IK-01) can be an effective treatment option for focal cartilage defects of the knee; however, surgeons must pay careful attention to the risk of postoperative joint infection.

Particulated Juvenile Articular Cartilage and Matrix-Induced Autologous Chondrocyte Implantation Are Cost-Effective for Patellar Chondral Lesions

PURPOSE

To compare the cost-effectiveness of nonoperative management, particulated juvenile allograft cartilage (PJAC), and matrix-induced autologous chondrocyte implantation (MACI) in the management of patellar chondral lesions.

METHODS

A Markov model was used to evaluate the cost-effectiveness of three strategies for symptomatic patellar chondral lesions: 1) nonoperative management, 2) PJAC, and 3) MACI. Model inputs (transition probabilities, utilities, and costs) were derived from literature review and an institutional cohort of 67 patients treated with PJAC for patellar chondral defects (mean age 26 years, mean lesion size 2.7 cm²). Societal and payer perspectives over a 15-year time horizon were evaluated. The principal outcome measure was the incremental cost-effectiveness ratio (ICER) using a $100,000/quality-adjusted life year (QALY) willingness-to-pay threshold. Sensitivity analyses were performed to assess the robustness of the model and the relative effects of variable estimates on base case conclusions.

RESULTS

From a societal perspective, nonoperative management, PJAC, and MACI cost $4,140, $52,683, and $83,073 and were associated with 5.28, 7.22, and 6.92 QALYs gained, respectively. PJAC and MACI were cost-effective relative to nonoperative management (ICERs $25,010/QALY and $48,344/QALY, respectively). PJAC dominated MACI in the base case analysis by being cheaper and more effective, but this was sensitive to the estimated effectiveness of both strategies. PJAC remained cost-effective if PJAC and MACI were considered equally effective.

CONCLUSIONS

In the management of symptomatic patellar cartilage defects, PJAC and MACI were both cost-effective compared to nonoperative management. Because of the need for one surgery instead of two, and less costly graft material, PJAC was cheaper than MACI. Consequently, when PJAC and MACI were considered equally effective, PJAC was more cost-effective than MACI. Sensitivity analyses accounting for the lack of robust long-term data for PJAC or MACI demonstrated that the cost-effectiveness of PJAC versus MACI depended heavily on the relative probabilities of yielding similar clinical results.

LEVEL OF EVIDENCE

III, economic and decision analysis.

Matrix-induced autologous chondrocyte implantation (mACI) versus autologous matrix-induced chondrogenesis (AMIC) for chondral defects of the knee: a systematic review

INTRODUCTION

Chondral defects of the knee are common and their treatment is challenging.

SOURCE OF DATA

PubMed, Google scholar, Embase and Scopus databases.

AREAS OF AGREEMENT

Both autologous matrix-induced chondrogenesis (AMIC) and membrane-induced autologous chondrocyte implantation (mACI) have been used to manage chondral defects of the knee.

AREAS OF CONTROVERSY

It is debated whether AMIC and mACI provide equivalent outcomes for the management of chondral defects in the knee at midterm follow-up. Despite the large number of clinical studies, the optimal treatment is still controversial.

GROWING POINTS

To investigate whether AMIC provide superior outcomes than mACI at midterm follow-up.

AREAS TIMELY FOR DEVELOPING RESEARCH

AMIC may provide better outcomes than mACI for chondral defects of the knee. Further studies are required to verify these results in a clinical setting.

State-of-the-art knowledge on the regulation of advanced therapy medicinal products

Advanced therapy medicinal products (ATMPs) constitute therapeutic agents based on obtained cells, tissues or genes representing a novel treatment opportunity in medicine. In addition, ATMPs are administered into the cells or tissues of humans from the patient's own cells, donors, or genetically modified cells. Recently, the field of developing ATMPs has become a point of attention due to the clinical efficacy expected in defeating incurable diseases such as cancers and neurodegenerative disorders. Currently, there are two modes regarding the distribution of ATMPs. First, ATMPs that might be legally authorized for marketing. Second, the patients are able to access unapproved ATMPs through the hospital exemption (HE) or clinical practice program or through the compassionate use and expanded access program. The aim of this review is to discuss state-of-the-art knowledge on the regulation of ATMPs and provide regulatory recommendations.

Differences in Clinical and Functional Outcomes Between Osteochondral Allograft Transplantation and Autologous Chondrocyte Implantation for the Treatment of Focal Articular Cartilage Defects

Background:

Articular cartilage pathology can result from a spectrum of origins, including trauma, osteochondritis dissecans, avascular necrosis, or degenerative joint disease.

Purpose:

To compare the differences in clinical and patient-reported outcomes after autologous chondrocyte implantation (ACI) versus osteochondral allograft transplantation (OCA) in patients with focal articular cartilage defects without underlying bone loss.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A retrospective review identified patients who underwent ACI or OCA between 2008 and 2016 for isolated grades 3 and 4 articular cartilage defects without underlying bone loss. Outcome measures included the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), International Knee Documentation Committee (IKDC) evaluation, and 12-Item Short Form Health Survey–Physical Component (SF-12-P) scores. Defect location, size, complications, and rate of subsequent surgery were determined.

Results:

Overall, 148 patients were included: 82 (55%) underwent ACI and 66 (45%) underwent OCA. The mean age at the time of surgery was 31.2 years within the ACI cohort and 37.7 years within the OCA cohort (P < .001); the mean follow-up for both cohorts was 6.7 years (P = .902). Within the ACI group, 28 (34%) patients had multifocal defects, 21 (26%) had defects confined to the femoral condyles, and 33 (40%) had defects in the patellofemoral region. Within the OCA group, 23 (35%) patients had multifocal defects, 30 (46%) had confined femoral condyle lesions, and 13 (20%) had patellofemoral defects. When comparing by lesion location, there were no significant differences in KOOS JR, and IKDC scores between the ACI and OCA cohorts (P < .05). There was, however, a significant difference for SF-12-P scores for FDD trochlear lesions. In both cohorts, traumatic patellofemoral pathology demonstrated lower patient-reported outcomes and higher failure rates than degenerative lesions. The overall rate of failure, defined as graft failure with revision surgery and/or conversion to arthroplasty, was significantly greater in the OCA group (21% vs 4%; P = .002).

Conclusion:

Study results indicated that ACI provides similar outcomes to OCA with or without concomitant procedures for the treatment of symptomatic articular cartilage defects in all lesion locations and may have a lower revision rate for multifocal and condylar lesions.

Chondral injuries in patients with recurrent patellar dislocation: a systematic review

Background

Patellar dislocations in patients presenting with recurrent patellofemoral instability can damage the surrounding structures, limiting patient’s participation to recreational activities and quality of life. This study evaluated frequency, location, and extent of associated injuries in patients with recurrent patellar dislocation.

Methods

This systematic review was conducted according to the PRISMA checklist. PubMed, Google scholar, Embase, and Web of Science databases were accessed in July 2021. All the published clinical studies reporting frequency, location, and extent of soft tissue lesions in patients with recurrent patellar dislocations were accessed.

Results

Data from 9 articles (232 patients) were retrieved. The mean age of the included patients was 21.2 ± 5.6 years. 84.8% of patients suffering from recurrent patellar dislocations demonstrated patellar chondral defects: medial facet (34.9%), while patellar crest (34.8%) and lateral facet (17%). 27.8% of patients demonstrated trochlear chondral injuries.

Conclusion

Chondral defects of the medial facet and the crest of the patella are the most common in patients with recurrent patellofemoral instability.

Exercise-induced piezoelectric stimulation for cartilage regeneration in rabbits

More than 32.5 million American adults suffer from osteoarthritis, and current treatments including pain medicines and anti-inflammatory drugs only alleviate symptoms but do not cure the disease. Here, we have demonstrated that a biodegradable piezoelectric poly(L-lactic acid) (PLLA) nanofiber scaffold under applied force or joint load could act as a battery-less electrical stimulator to promote chondrogenesis and cartilage regeneration. The PLLA scaffold under applied force or joint load generated a controllable piezoelectric charge, which promoted extracellular protein adsorption, facilitated cell migration or recruitment, induced endogenous TGF-β via calcium signaling pathway, and improved chondrogenesis and cartilage regeneration both in vitro and in vivo. Rabbits with critical-sized osteochondral defects receiving the piezoelectric scaffold and exercise treatment experienced hyaline-cartilage regeneration and completely healed cartilage with abundant chondrocytes and type II collagen after 1 to 2 months of exercise (2 to 3 months after surgery including 1 month of recovery before exercise), whereas rabbits treated with nonpiezoelectric scaffold and exercise treatment had unfilled defect and limited healing. The approach of combining biodegradable piezoelectric tissue scaffolds with controlled mechanical activation (via physical exercise) may therefore be useful for the treatment of osteoarthritis and is potentially applicable to regenerating other injured tissues.

Membrane scaffolds for matrix-induced autologous chondrocyte implantation in the knee: a systematic review

INTRODUCTION

Chondral defects of the knee are common and their management is challenging.

SOURCE OF DATA

Current scientific literature published in PubMed, Google scholar, Embase and Scopus.

AREAS OF AGREEMENT

Membrane-induced autologous chondrocyte implantation (mACI) has been used to manage chondral defects of the knee.

AREAS OF CONTROVERSY

Hyaluronic acid membrane provides better outcomes than a collagenic membrane for mACI in the knee at midterm follow-up is controversial.

GROWING POINTS

To investigate whether hyaluronic acid membrane may provide comparable clinical outcomes than collagenic membranes for mACI in focal defects of the knee.

AREAS TIMELY FOR DEVELOPING RESEARCH

Hyaluronic acid membrane yields a lower rate of failures and revision surgeries for mACI in the management of focal articular cartilage defects of the knee compared with collagenic scaffolds at midterm follow-up. No difference was found in patient reported outcome measures (PROMs). Further comparative studies are required to validate these results in a clinical setting.

Concomitant Osteotomy Reduces Risk of Reoperation Following Cartilage Restoration Procedures of the Knee: A Matched Cohort Analysis

OBJECTIVE

The objective of this study is to compare the (1) reoperation rates, (2) 30-day complication rates, and (3) cost differences between patients undergoing isolated autologous chondrocyte implantation (ACI) or osteochondral allograft transplantation (OCA) procedures alone versus patients with concomitant osteotomy.

STUDY DESIGN

Retrospective cohort study, level III.

DESIGN

Patients who underwent knee ACI (Current Procedural Terminology [CPT] 27412) or OCA (CPT 27415) with minimum 2-year follow-up were queried from a national insurance database. Resulting cohorts of patients that underwent ACI and OCA were then divided into patients who underwent isolated cartilage restoration procedure and patients who underwent concomitant osteotomy (CPT 27457, 27450, 27418). Reoperation was defined by ipsilateral knee procedure after the index surgery. The 30-day postoperative complication rates were assessed using ICD-9-CM codes. The cost per patient was calculated.

RESULTS

A total of 1,113 patients (402 ACI, 67 ACI + osteotomy, 552 OCA, 92 OCA + osteotomy) were included (mean follow-up of 39.0 months). Reoperation rate was significantly higher after isolated ACI or OCA compared to ACI or OCA plus concomitant osteotomy (ACI 68.7% vs. ACI + osteotomy 23.9%; OCA 34.8% vs. OCA + osteotomy 16.3%). Overall complication rates were similar between isolated ACI (3.0%) and ACI + osteotomy (4.5%) groups and OCA (2.5%) and OCA + osteotomy (3.3%) groups. Payments were significantly higher in the osteotomy groups at day of surgery and 9 months compared to isolated ACI or OCA, but costs were similar by 2 years postoperatively.

CONCLUSIONS

Concomitant osteotomy at the time of index ACI or OCA procedure significantly reduces the risk of reoperation with a similar rate of complications and similar overall costs compared with isolated ACI or OCA.

Failures, Reoperations, and Improvement in Knee Symptoms Following Matrix-Assisted Autologous Chondrocyte Transplantation: A Meta-Analysis of Prospective Comparative Trials

OBJECTIVE

Though multiple high-level comparative studies have been performed for matrix-assisted autologous chondrocyte transplantation (MACT), quantitative reviews synthesizing best-available clinical evidence on the topic are lacking.

DESIGN

A meta-analysis was performed of prospective randomized or nonrandomized comparative studies utilizing MACT. A total of 13 studies reporting 13 prospective trials (9 randomized, 5 nonrandomized) were included (658 total study participants at weighted mean 3.1 years follow-up, range 1-7.5 years).

RESULTS

Reporting and methodological quality was moderate according to mean Coleman (59.4 SD 7.6), Delphi (3.0 SD 2.1), and MINORS (Methodological Index For Non-Randomized Studies) scores (20.2 SD 1.6). There was no evidence of small study or reporting bias. Effect sizes were not correlated with reporting quality, financial conflict of interest, sample size, year of publication, or length of follow-up (P > 0.05). Compared to microfracture, MACT had greater improvement in International Knee Documentation Committee (IKDC)-subjective and Knee Injury and Osteoarthritis Outcome Pain Subscale Score (KOOS)-pain scores in randomized studies (P < 0.05). Accelerated weight-bearing protocols (6 or 8 weeks) resulted in greater improvements in IKDC-subjective and KOOS-pain scores than standard protocols (8 or 11 weeks) for MACT in randomized studies (P < 0.05) with insufficient nonrandomized studies for pooled analysis.

CONCLUSIONS

Compared to microfracture, MACT has no increased risk of clinical failure and superior improvement in patient-reported outcome scores. Compared to MACT with standardized postoperative weight-bearing protocols, accelerated weight-bearing protocols have no increased risk of clinical failure and show superior improvement in patient-reported outcome scores. There is limited evidence regarding MACT compared to first-generation autologous chondrocyte implantation, mosaicplasty, and mesenchymal stem cell therapy without compelling differences in outcomes.

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

Biologic Augmentation for the Operative Treatment of Osteochondral Defects of the Knee: A Systematic Review

Background:

Various surgical treatment options exist for repairing, replacing, or regenerating tissue to fill osteochondral defects. Biologic augmentation has been increasingly studied as an adjunct in the surgical treatment of osteochondral defects of the knee in animal and human models.

Purpose/Hypothesis:

The purpose of the study was to systematically review use of platelet-rich plasma (PRP) and bone marrow concentrate (BMC) augmentation in the surgical treatment of osteochondral knee defects and to describe the outcomes. It was hypothesized that both PRP and BMC augmentation will result in improved outcomes in osteochondral knee surgery in both animal and human models.

Study Design:

Systematic review.

Methods:

PubMed, MEDLINE, and Embase were searched for studies relating to PRP or BMC and treatment of osteochondral defects of the knee, from database inception to February 1, 2020. Included were articles that (1) studied PRP or BMC augmentation; (2) used osteochondral autograft, allograft, or biologic scaffold; and (3) treated osteochondral defects in the knee. Data on use of PRP or BMC, outcomes assessed, and results were recorded for each publication.

Results:

Of the 541 articles identified initially, 17 were included in the final review. Five articles studied osteochondral grafts in animals, 5 studied biologic scaffolds in animals, and 7 studied scaffolds or allografts in humans; the combined sample size was 202 patients. Of 4 histologic scaffold studies, 3 PRP-augmented scaffold studies identified histologic improvements in regenerated cartilage in animal models, while 1 BMC study demonstrated similar improvement in histologic scores of BMC-augmented scaffolds compared with controls. Three studies associated greater collagen type 2 and glycosaminoglycan content with PRP treatment. Comparative studies found that both augments increase osteogenic proteins, including bone morphogenetic protein–2 and osteoprotegerin. Two of 3 studies on BMC-augmented osteochondral allografts reported no difference in radiographic features postoperatively. Long-term improvement in clinical and radiographic outcomes of PRP-augmented scaffolds was demonstrated in 1 human study.

Conclusion:

Animal studies suggest that biologics possess potential as adjuncts to surgical treatment of osteochondral knee defects; however, clinical data remain limited.

Methods of Modification of Mesenchymal Stem Cells and Conditions of Their Culturing for Hyaline Cartilage Tissue Engineering

The use of mesenchymal stromal cells (MSCs) for tissue engineering of hyaline cartilage is a topical area of regenerative medicine that has already entered clinical practice. The key stage of this procedure is to create conditions for chondrogenic differentiation of MSCs, increase the synthesis of hyaline cartilage extracellular matrix proteins by these cells and activate their proliferation. The first such works consisted in the indirect modification of cells, namely, in changing the conditions in which they are located, including microfracturing of the subchondral bone and the use of 3D biodegradable scaffolds. The most effective methods for modifying the cell culture of MSCs are protein and physical, which have already been partially introduced into clinical practice. Genetic methods for modifying MSCs, despite their effectiveness, have significant limitations. Techniques have not yet been developed that allow studying the effectiveness of their application even in limited groups of patients. The use of MSC modification methods allows precise regulation of cell culture proliferation, and in combination with the use of a 3D biodegradable scaffold, it allows obtaining a hyaline-like regenerate in the damaged area. This review is devoted to the consideration and comparison of various methods used to modify the cell culture of MSCs for their use in regenerative medicine of cartilage tissue.

Probing Multicellular Tissue Fusion of Cocultured Spheroids-A 3D-Bioassembly Model

While decades of research have enriched the knowledge of how to grow cells into mature tissues, little is yet known about the next phase: fusing of these engineered tissues into larger functional structures. The specific effect of multicellular interfaces on tissue fusion remains largely unexplored. Here, a facile 3D-bioassembly platform is introduced to primarily study fusion of cartilage-cartilage interfaces using spheroids formed from human mesenchymal stromal cells (hMSCs) and articular chondrocytes (hACs). 3D-bioassembly of two adjacent hMSCs spheroids displays coordinated migration and noteworthy matrix deposition while the interface between two hAC tissues lacks both cells and type-II collagen. Cocultures contribute to increased phenotypic stability in the fusion region while close initial contact between hMSCs and hACs (mixed) yields superior hyaline differentiation over more distant, indirect cocultures. This reduced ability of potent hMSCs to fuse with mature hAC tissue further underlines the major clinical challenge that is integration. Together, this data offer the first proof of an in vitro 3D-model to reliably study lateral fusion mechanisms between multicellular spheroids and mature cartilage tissues. Ultimately, this high-throughput 3D-bioassembly model provides a bridge between understanding cellular differentiation and tissue fusion and offers the potential to probe fundamental biological mechanisms that underpin organogenesis.

Evaluation of regenerated cartilage using T2 mapping methods after opening-wedge high tibial osteotomy with microfracture at the cartilage defect: a preliminary study

PURPOSE

This study evaluated the regenerated cartilage after opening-wedge high tibial osteotomy (OWHTO) with concomitant microfracture by second-look arthroscopy, Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score and magnetic resonance imaging (MRI) T2 mapping. It was hypothesised that cartilage regeneration can be achieved by HTO, but the quality of regenerated cartilage is not normal cartilage.

METHODS

OWHTO was performed in eight knees of seven patients (mean age, 57.6 ± 5.2 years). Microfracture for the cartilage defect was performed followed by OWHTO, and second-look arthroscopy was performed at the time of plate removal (14.1 ± 4.5 months after OWHTO). MRI was assessed at three months and one year after surgery. The status of articular cartilage regeneration was assessed by the ICRS grade, MOCART score and T2 value.

RESULTS

The number of subjects in ICRS grade 1/2/3/4 changed significantly from 0/0/4/4 preoperatively to 0/2/6/0 postoperatively in the medial femoral condyle (MFC) (P < 0.05) and 0/0/0/8 preoperatively to 0/0/7/1 postoperatively in the medial tibial plateau (MTP) (P < 0.05). Mean MOCART scores for MFC and MTP at one year after surgery exhibited significant increases compared with the results at three months after surgery. Mean T2 values for MFC and MTP did not differ at three months and one year after surgery.

CONCLUSION

The appearance and morphological evaluation by ICRS grade and MOCART score of regenerated cartilage were improved after OWHTO with concomitant microfracture. However, there were no significant qualitative differences in T2 values. This suggests that the regenerated cartilage tissue was likely to be insufficient cartilage.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Biofabrication Strategies for Musculoskeletal Disorders: Evolution towards Clinical Applications

Biofabrication has emerged as an attractive strategy to personalise medical care and provide new treatments for common organ damage or diseases. While it has made impactful headway in e.g., skin grafting, drug testing and cancer research purposes, its application to treat musculoskeletal tissue disorders in a clinical setting remains scarce. Albeit with several in vitro breakthroughs over the past decade, standard musculoskeletal treatments are still limited to palliative care or surgical interventions with limited long-term effects and biological functionality. To better understand this lack of translation, it is important to study connections between basic science challenges and developments with translational hurdles and evolving frameworks for this fully disruptive technology that is biofabrication. This review paper thus looks closely at the processing stage of biofabrication, specifically at the bioinks suitable for musculoskeletal tissue fabrication and their trends of usage. This includes underlying composite bioink strategies to address the shortfalls of sole biomaterials. We also review recent advances made to overcome long-standing challenges in the field of biofabrication, namely bioprinting of low-viscosity bioinks, controlled delivery of growth factors, and the fabrication of spatially graded biological and structural scaffolds to help biofabricate more clinically relevant constructs. We further explore the clinical application of biofabricated musculoskeletal structures, regulatory pathways, and challenges for clinical translation, while identifying the opportunities that currently lie closest to clinical translation. In this article, we consider the next era of biofabrication and the overarching challenges that need to be addressed to reach clinical relevance.