Autologous chondrocyte implantation: natural history of postimplantation periosteal hypertrophy and effects of repair-site debridement on outcome

[Advances in the Treatment of Osteochondral Lesions of the Talus]

Osteochondral lesion of the talus (OLT) is a localized cartilage and subchondral bone injury of the talus trochlea. OLT is caused by trauma and other reasons, including osteochondritis dissecans of the talus (OCD) and talus osteochondral tangential fracture. OLT can develop from being asymptomatic to subchondral bone cysts accompanied by deep ankle pain. OLT tends to occur on the medial and lateral sides of the talar vault. OLT seriously affects the patients' life and work and may even lead to disability. Herein, we reviewed advances in the treatment of OLT and the strengths and weaknesses of various treatments. Different treatment methods, including conservative treatments and surgical treatments, can be adopted according to the different subtypes or clinical symptoms of OLT. Conservative treatments mostly relieve symptoms in the short term and only slow down the disease. In recent years, it has been discovered that platelet-rich plasma injection, microfracture, periosteal bone grafting, talar cartilage transplantation, allograft bone transplantation, reverse drilling under robotic navigation, and other methods can achieve considerable benefits when each of these treatment methods is applied. Furthermore, microfracture combined with platelet-rich plasma injections, microfracture combined with cartilage transplantation, and various other treatment methods combined with anterior talofibular ligament repair have all led to good treatment outcomes.

Clinical Potential of Cellular Material Sources in the Generation of iPSC-Based Products for the Regeneration of Articular Cartilage

Inflammatory joint diseases, among which osteoarthritis and rheumatoid arthritis are the most common, are characterized by progressive degeneration of the cartilage tissue, resulting in the threat of limited or lost joint functionality in the absence of treatment. Currently, treating these diseases is difficult, and a number of existing treatment and prevention measures are not entirely effective and are complicated by the patients' conditions, the multifactorial nature of the pathology, and an incomplete understanding of the etiology. Cellular technologies based on induced pluripotent stem cells (iPSCs) can provide a vast cellular resource for the production of artificial cartilage tissue for replacement therapy and allow the possibility of a personalized approach. However, the question remains whether a number of etiological abnormalities associated with joint disease are transmitted from the source cell to iPSCs and their chondrocyte derivatives. Some data state that there is no difference between the iPSCs and their derivatives from healthy and sick donors; however, there are other data indicating a dissimilarity. Therefore, this topic requires a thorough study of the differentiation potential of iPSCs and the factors influencing it, the risk factors associated with joint diseases, and a comparative analysis of the characteristics of cells obtained from patients. Together with cultivation optimization methods, these measures can increase the efficiency of obtaining cell technology products and make their wide practical application possible.

Mid- to Long-Term Clinical Outcomes of Cartilage Restoration of Knee Joint with Allogenic Next-Generation Matrix-Induced Autologous Chondrocyte Implantation (MACI)

OBJECTIVE

Cartilage defect is a common pathology still lacking a unified treating option. The purpose of this retrospective study is to evaluate the safety, efficacy, and clinical and radiological outcome of cartilage restoration of knee joint with allogenic next-generation Matrix-Induced Autologous Chondrocyte Implantation (MACI) for the first time, as well as the correlation between postoperative clinical and radiological outcomes and preoperative patient history and demographics.

METHODS

From July 2014 to August 2020, 15 patients who went through cartilage restoration with allogenic next-generation MACI were included in this study. Patient demographics and PROM including the International Knee Documentation Committee (IKDC) subjective knee score, Lysholm score, Tegner Activity Scale (TAS), and Knee Injury and Osteoarthritis Outcome Score (KOOS) were obtained preoperatively, at 3, 6, 12 months postoperatively and the last follow-up using an online questionnaire platform. MOCART 2.0 score was calculated at the last follow-up. Analysis of variance (ANOVA) was used to compare PROM pre- and post-operation, with two-tailed p < 0.05 defined as statistical significant. Pearson correlation coefficient was used to evaluate correlation between the PROM and MOCART 2.0 score at the last follow-up with patients demorgraphics.

RESULTS

All patients were followed for an average of 66.47 ± 24.15 months (range, 21-93). All patients were satisfied with the outcome of the surgery and no complication was reported at the end of the study. No significant improvement was observed until 1 year after the implantation, except for IKDC score at 6 months. All PROM showed significant improvement 1 year post-op except for Lysholm score and TAS, which also increased significantly at the time of the last follow-up. Pearson correlation coefficient showed that the size of the defect, before or after debridement, was significantly negatively correlated with final KOOS-Pain (before debridement: r = -0.57, p < 0.05; after debridement: r = -0.54, p < 0.05) and KOOS-Symptoms score (before debridement: r = -0.66, p < 0.05; after debridement: r = -0.67, p < 0.05). The MOCART 2.0 score was found significantly and negatively correlated with BMI (r = -0.60, p < 0.05), and significantly and positively correlated with Lysholm score (r = 0.70, p < 0.05).

CONCLUSION

The next generation MACI with autologous chondrocyte and allogenic chondrocyte ECM scaffold could be used to treat focal articular cartilage defect in the knee joint safely and efficiently with lasting promising outcomes for more than 5 years. The size of the defects should be considered the most negatively correlated parameters influencing the postoperative clinical outcomes.

Click chemistry-based pre-targeting cell delivery for cartilage regeneration

A fraction of the OA patient population is affected by post-traumatic osteoarthritis (PTOA) following acute joint injuries. Stopping or reversing the progression of PTOA following joint injury could improve long-term functional outcomes, reduced disability, and medical costs. To more effectively treat articular cartilage injury, we have developed a novel cell-based therapy that involves the pre-targeting of apoptotic chondrocytes and the delivery of healthy, metabolically active chondrocytes using click chemistry. Specifically, a pre-targeting agent was prepared via conjugating apoptotic binding peptide (ApoPep-1) and trans-cyclooctene (TCO) onto polyethylene glycol (PEG) polymer carrier. The pre-targeting agent would be introduced to injured areas of articular cartilage, leading to the accumulation of TCO groups on the injured areas from actively binding to apoptotic chondrocytes. Subsequently, methyltetrazine (Tz)-bearing chondrocytes would be immobilized on the surface of TCO-coated injured cartilage via Tz-TCO click chemistry reaction. Using an ex vivo human cartilage explant PTOA model, the effectiveness of this new approach was evaluated. Our studies show that this novel approach (Tz-TCO click chemistry) significantly enhanced the immobilization of healthy and metabolically active chondrocytes to the areas of apoptotic chondrocytes. Histological analyses demonstrated that this treatment regimen would significantly reduce the area of cartilage degeneration and enhance ECM regeneration. The results support that Tz-TCO click chemistry-mediated cell delivery approach has great potential in clinical applications for targeting and treatment of cartilage injury.

Clinical and Radiographic Outcomes After Treatment of Patellar Chondral Defects: A Systematic Review

CONTEXT

There is currently no evidence-based consensus on how to treat a full-thickness, symptomatic articular cartilage injury of the patella, although numerous treatment options are available.

OBJECTIVE

To systematically evaluate the functional outcomes after operative treatment of patellar cartilage lesions. Our secondary purpose was to evaluate radiographic outcomes after treatment.

DATA SOURCES

PubMed, Cochrane, and Embase.

STUDY SELECTION

Studies published between January 1, 1990 and December 31, 2018 that included patient-reported functional outcomes for patients after operative treatment of patellar chondral defects at a minimum 2-year follow-up were included.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

MINORS (Methodological Index for Non-Randomized Studies) score, level of evidence, sample size, demographic data, follow-up data, intervention, functional outcome scores, and magnetic resonance imaging (MRI) data were collected.

RESULTS

The review identified 10 studies and 293 patients receiving cartilage restoration procedures for patellar chondral defects with extractable clinical and radiographic results and data on complications and reoperations. All treatments (autologous chondrocyte implantation [ACI], matrix-induced ACI [MACI], autologous osteochondral transplantation [AOT]) utilized in the management of patellar chondral lesions, with the exception of isolated particulated juvenile articular cartilage, demonstrated statistically significant improvements in functional outcome scores compared with preoperative measurements at a minimum of 2-year follow-up. Postoperative MRIs were obtained in 6 studies and found that regardless of treatment, moderate-to-complete infill of patellar cartilage lesions was seen in the majority of patients. While failure rates were low for the various treatment modalities, rates of reoperation were substantial, with up to 40% to 60% reoperation rate seen after ACI.

CONCLUSION

Patients treated with ACI, MACI, and AOT all demonstrated statistically significant improvements in functional outcome scores with radiographic evidence of healing at minimum of 2-year follow-up. Evidence is insufficient to recommend one particular treatment over another.

Costal Chondrocyte-Derived Pellet-Type Autologous Chondrocyte Implantation for Treatment of Articular Cartilage Defect

BACKGROUND

Because articular chondrocyte-based autologous chondrocyte implantations (ACIs) have restrictively restored articular cartilage defects, alternative cell sources as a new therapeutic option for cartilage repair have been introduced.

PURPOSE

To assess whether implantation of a costal chondrocyte-derived pellet-type (CCP) ACI allows safe, functional, and structural restoration of full-thickness cartilage defects in the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

In this first-in-human study, 7 patients with symptomatic, full-thickness cartilage lesions were enrolled. The chondrocytes isolated from the patients' costal cartilage were expanded, followed by 3-dimensional pellet culture to prepare the CCP-ACI. Implantation of the pellets was performed via minimal arthrotomy and secured with a fibrin sealant. Clinical scores, including the International Knee Documentation Committee (IKDC) subjective, Lysholm, and Tegner activity scores, were estimated preoperatively and at 1, 2, and 5 years postoperatively. High-resolution magnetic resonance imaging was also performed to evaluate cartilage repair as well as to calculate the MOCART (magnetic resonance observation of cartilage repair tissue) score.

RESULTS

The costal chondrocytes of all patients formed homogeneous-sized pellets, which showed the characteristics of the hyaline cartilaginous tissue with lacunae-occupied chondrocytes surrounded by glycosaminoglycan and type II collagen-rich extracellular matrix. There were no treatment-related serious adverse events during the 5-year follow-up period. Significant improvements were seen in all clinical scores from preoperative baseline to the 5-year follow-up (IKDC subjective score, 34.67 to 75.86; Lysholm score, 34.00 to 85.33; Tegner activity score, 1.17 to 4.67; and MOCART score, 28.33 to 83.33). Two patients had complete defect filling on magnetic resonance imaging evaluation at 1 year. Moreover, at 5 years postoperatively, complete defect filling was observed in 4 patients, and hypertrophy or incomplete defect filling (50%-100%) was observed in 2 patients.

CONCLUSION

The overall results of this clinical study suggest that CCP-ACI can emerge as a promising therapeutic option for articular cartilage repair with good clinical outcomes and structural regeneration and with stable results at midterm follow-up.

REGISTRATION

NCT03517046 ( ClinicalTrials.gov identifier).

Autologous osteochondral transplantation method of treatment for patellar osteochondral lesions

PURPOSE

This study evaluated the functional and clinical outcomes of the subjects with symptomatic osteochondral lesions on articular surface of patella, who were treated with autologous osteochondral transplantation (AOT) method.

STUDY PLAN

AOT method was applied for the treatment of 14 subjects (eight men and six women; mean age 29.7 years; range 19-49 years) with symptomatic patellar osteochondral lesions between March 2008 and April 2013. After a mean follow-up period of 3.7 years (range 32-80 months), pre- and postoperative clinical and functional evaluations of the patients were performed using Visual Pain Scale (VPS), Lysholm Knee Scoring Scale, and Kujala Anterior Knee Pain Scale. Wilcoxon test was used for statistical evaluation of pre- and postoperative outcomes. Improvement of the lesions was assessed by magnetic resonance imaging (MRI) at year 1 postoperatively at the earliest.

RESULTS

The mean lesion size was 1.32 cm² (range 0.8-1.8 cm²). The mean pre- and postoperative VPS values were calculated to be 75.5 ± 12.32 (range 46-92) and 17.57 ± 10.21 (range 0-40), respectively ( p < 0.01). The mean pre- and postoperative Lysholm knee scores were 44.57 ± 9.35 (range 26-65) and 80 ± 6.9 (range 70-94), respectively ( p < 0.01), and the mean pre- and postoperative Kujala anterior knee pain scores were 48.21 ± 7.78 (range 38-68) and 78.42 ± 7.06 (range 70-96), respectively ( p < 0.01). MRI taken at year 1 postoperatively showed that the autograft bone tissue was sufficiently incorporated into the recipient site in all patients; an even articular surface was formed, but the thickness of the cartilage tissue was mostly uneven between the adjacency of the recipient site and the autograft, which caused no negative effect on clinical and functional outcomes.

CONCLUSIONS

Despite the difference in thickness of the cartilage tissue between the recipient and the donor site, the AOT technique for the treatment of patellar osteochondral lesions resolves the symptoms of the patient and ensures an apparent functional and clinical improvement even if an articular surface could be created.

Report on a large animal study with Göttingen Minipigs where regenerates and controls for articular cartilage were created in a large number. Focus on the conditions of the operated stifle joints and suggestions for standardized procedures

The characterization of regenerated articular cartilage (AC) can be based on various methods, as there is an unambiguous accepted criterion neither for the natural cartilage tissue nor for regenerates. Biomechanical aspects should be considered as well, leading to the need for more equivalent samples. The aim of the study was to describe a large animal model where 8 specimens of regenerated AC can be created in one animal plus the impact of two surgeries on the welfare of the animals. The usefulness of the inclusion of a group of untreated animals (NAT) was to analyzed. Based on the histological results the conditions of the regenerates were to be described and the impact on knee joints were to be explored in terms of degenerative changes of the cartilage. The usefulness of the statistical term “effect size” (ES) will be explained with histological results. We analyzed an animal model where 8 AC regenerates were obtained from one Göttingen Minipig, on both sides of the trochleae. 60 animals were divided into 6 groups of 10 each, where the partial thickness defects in the trochlea were filled with matrices made of Collagen I with or without autologous chondrocytes or left empty over the healing periods of 24 and 48 weeks. One additional control group consisting of 10 untreated animals was used to provide untouched “external” cartilage. We harvested 560 samples of regenerated tissue and “external” controls, besides that, twice the number of further samples from other parts of the joints referred to as “internal” controls were also harvested. The animals recovered faster after the 1^st operation when the defects were set compared to the 2^nd operation when the defects were treated. 9% of all animals were lost. Other complications were for example superficial infections, seroma, diarrhea, febrile state and an injury of a claw. The histological results of the treatments proved the robustness of the study design where we included an “external” control group (NAT) in which the animals were not operated. Comparable significant differences between treated groups and the NAT group were detected both after ½ year and after 1 year. Spontaneous regenerated AC as control revealed differences after an observation time of nearly 1 year. The impact of the treatment on cartilage adjacent to the defect as well as the remaining knee joint was low. The ES was helpful for planning the study as it is shown that the power of a statistical comparison seems to be more influenced by the ES than by the sample size. The ranking of the ES was done exemplarily, listing the results according to their magnitude, thus making the results comparable. We were able to follow the 3 R requirements also in terms of a numerical reduction of animals due to the introduction of a group of untreated animals. This makes the model cost effective. The presented study may contribute as an improvement of the standardization of large animal models for research and regulatory requirements for regenerative therapies of AC.

Matrix-Associated Autologous Chondrocyte Implantation Is an Effective Treatment at Midterm Follow-up in Adolescents and Young Adults

Background

Autologous chondrocyte implantation (ACI) is an established method for treating cartilage defects in the knee of adult patients. However, less is known about its effectiveness in adolescents.

Hypothesis

Third-generation matrix-associated ACI (MACI) using spheroids (co.don chondrosphere/Spherox) is an effective and safe treatment for articular cartilage defects in adolescents aged 15 to 17 years, with outcomes comparable with those for young adults aged 18 to 34 years.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 71 patients (29 adolescents, 42 young adults) who had undergone ACI using spheroids were evaluated retrospectively in this multicenter study. For adolescents, the mean defect size was 4.6 ± 2.4 cm², and the follow-up range was 3.5 to 8.0 years (mean, 63.3 months). For young adults, the mean defect size was 4.7 ± 1.2 cm², and the follow-up range was 3.8 to 4.3 years (mean, 48.4 months). At the follow-up assessment, outcomes were assessed by using validated questionnaires (Knee injury and Osteoarthritis Outcome Score [KOOS], International Knee Documentation Committee [IKDC] subjective knee evaluation form and current health assessment form, and modified Lysholm score), the magnetic resonance observation of cartilage repair tissue (MOCART) score, and if relevant, time to treatment failure. Safety was assessed by the treatment failure rate.

Results

No significant difference between the 2 study groups was found for KOOS, IKDC, or MOCART scores, with all patients achieving high functional values. A significant difference was found in the modified Lysholm score, favoring the young adult group over the adolescent group (22.3 ± 1.9 vs 21.0 ± 2.4, respectively; P = .0123). There were no differences between the rates of treatment failure, with 3% in the adolescent group and 5% in the young adult group.

Conclusion

Third-generation MACI using spheroids is a safe and effective treatment for large cartilage defects of the knee in adolescents at midterm follow-up. Outcomes are comparable with those for young adults after ACI.

Graft Hypertrophy After Third-Generation Autologous Chondrocyte Implantation Has No Correlation With Reduced Cartilage Quality: Matched-Pair Analysis Using T2-Weighted Mapping

BACKGROUND

Graft hypertrophy is common after matrix-based autologous chondrocyte implantation (ACI) in the knee joint. However, it is not clear whether graft hypertrophy is a complication or an adjustment reaction in the cartilage regeneration after ACI.

PURPOSE

To analyze the cartilage quality of the ACI regeneration with graft hypertrophy using T2-weighted mapping.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 91 patients with isolated cartilage defects (International Cartilage Repair Society [ICRS] grade III-IV) of the knee were treated with Novocart 3D, a third-generation, matrix-based, ACI procedure in the knee joint. All patients were evaluated with a standardized magnetic resonance imaging protocol after 3, 6, 12, 24, 36, and 48 months postoperatively. For morphological and biochemical assessment, the T2-weighted relaxation times of the ACI grafts as well as the healthy surrounding cartilage were determined. The results of the 20 patients with graft hypertrophy (hypertrophic group) were compared with the results of 21 matched patients without graft hypertrophy (nonhypertrophic group) after ACI. Match-paired analysis was performed by comparison of age, defect size, and body mass index.

RESULTS

The T2-weighted relaxation times of the ACI graft showed significant improvement, with values decreasing from 52.1 milliseconds to 33.3 milliseconds after 48 months. After 12 months, the T2-weighted relaxation times were constant and comparable with the healthy surrounding cartilage. Graft hypertrophy was seen in 22% (n = 20) of the patients who underwent ACI. A significant difference in T2-weighted relaxation times between the hypertrophic and nonhypertrophic ACI grafts could not be found except after 36 months (hypertrophic T2-weighted relaxation time/nonhypertrophic T2-weighted relaxation time: 3 months, 48.0/56.4 ms, P = .666; 6 months, 45.6/42.5 ms, P = .280; 12 months, 39.3/34.7 ms, P = .850; 24 months, 34.8/32.2 ms, P = .742; 36 months, 34.6/38.2 ms, P = .030; 48 months, 34.2/32.3 ms, P = .693).

CONCLUSION

The T2-weighted relaxation time of the ACI graft cartilage showed significant improvements over the observation period of 4 years postoperatively. After 2 years, graft maturation was completed. Graft hypertrophy after ACI was seen in 22% of the patients. Reduced cartilage quality could not be found in patients with graft hypertrophy after ACI.

Clinical and MRI Outcomes After Surgical Treatment of Osteochondral Lesions of the Talus in Skeletally Immature Children

BACKGROUND

The literature on the osteochondral lesion of the talus (OLT) in skeletally immature children is scarce and little is known about the clinical outcomes and the radiologic appearance of these lesions after surgical treatment. The aim of this study was to assess mid-term clinical and magnetic resonance imaging (MRI) outcomes after arthroscopic microfracture (AM) of OLT in skeletally immature children.

METHODS

Thirteen patients with OLT treated by AM before skeletal maturity were included in the study. The Berndt and Harty outcome question, the Single Assessment Numeric Evaluation question, and the Martin questionnaire were used to obtain patients' subjective satisfaction with their operated ankle. Functional outcomes preoperatively and postoperatively were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) score. MRI scans were performed postoperatively using a magnetic resonance observation of cartilage repair tissue (MOCART) scoring system for 11 ankles.

RESULTS

The median age was 15 years (range, 13 to 16 y) and the median follow-up period was 5.6 years (range, 3.8 to 13.6 y). According to the Berndt and Harty outcome question, good clinical results were reported in 10 (76.9%) and fair in 3 (23.1%) patients. The postoperative AOFAS score was significantly improved when compared with the preoperative AOFAS score, with a mean increase of 35 points (P<0.001). The overall MOCART score was 65 (range, 10 to 75). MRI variables of the MOCART scoring system showed no association with clinical outcomes.

CONCLUSIONS

AM seems to be an effective surgical method for the treatment of OLT in skeletally immature children.

LEVEL OF EVIDENCE

Level IV-therapeutic studies, case series.

Matrix-Induced Autologous Chondrocyte Implantation (MACI) Using a Cell-Seeded Collagen Membrane Improves Cartilage Healing in the Equine Model

BACKGROUND

Autologous chondrocyte implantation (ACI) using a collagen scaffold (matrix-induced ACI; MACI) is a next-generation approach to traditional ACI that provides the benefit of autologous cells and guided tissue regeneration using a biocompatible collagen scaffold. The MACI implant also has inherent advantages including surgical implantation via arthroscopy or miniarthrotomy, the elimination of periosteal harvest, and the use of tissue adhesive in lieu of sutures. This study evaluated the efficacy of the MACI implant in an equine full-thickness cartilage defect model at 1 year.

METHODS

Autologous chondrocytes were seeded onto a collagen type-I/III membrane and implanted into one of two 15-mm defects in the femoral trochlear ridge of 24 horses. Control defects either were implanted with cell-free collagen type-I/III membrane (12 horses) or were left ungrafted as empty defects (12 horses). An additional 3 horses had both 15-mm defects remain empty as nonimplanted joints. The repair was scored by second-look arthroscopy (12 weeks), and necropsy examination (53 weeks). Healing was assessed by arthroscopic scoring, gross assessment, histology and immunohistology, cartilage matrix component assay, and gene expression determination. Toxicity was examined by prostaglandin E2 formation in joint fluid, and lymph node morphology combined with histologic screening of organs.

RESULTS

MACI-implanted defects had improved gross healing and composite histologic scores, as well as increases in chondrocyte predominance, toluidine blue-stained matrix, and collagen type-II content compared with scaffold-only implanted or empty defects. There was minimal evidence of reaction to the implant in the synovial membrane (minor perivascular cuffing), subchondral bone, or cartilage. There were no adverse clinical effects, signs of organ toxicity, or evidence of chondrocytes or collagen type-I/III membrane in draining lymph nodes.

CONCLUSIONS

The MACI implant appeared to improve cartilage healing in a critical-sized defect in the equine model compared with collagen matrix alone.

CLINICAL RELEVANCE

These results indicate that the MACI implant is quick to insert, provides chondrocyte security in the defect, and improves cartilage healing compared with ACI.

Patellofemoral Articulating Osteochondral (Kissing) Lesion Treated with Autologous Chondrocyte Implantation: A Case Report

INTRODUCTION

Autologous chondrocyte implantation (ACI) is an effective treatment for chondral defects of the knee; however, its use in kissing lesions is less well documented.

CASE REPORT

A 23-year-old female with a kissing lesion of the patellofemoral compartment on magnetic resonance imaging underwent two-stage ACI to her medial patella (20 mm × 22 mm) and medial trochlea (27 mm × 18 mm). At 1-year follow-up, the patient had returned to all activities with near-complete resolution of symptoms and substantial improvement in clinical outcome scores.

CONCLUSION

Patients with kissing lesions of the knee can be treated successfully with ACI performed to multiple sites.

Synthetic Poly(Vinylalcohol)-Based Membranes for Cartilage Surgery and Repair

Cell-based therapies for cartilage repair are continually being developed to treat osteoarthritis. The cells are either introduced directly by intra-articular injection or via a cell-seeded matrix scaffold. Here, poly(vinylalcohol)-based membranes are developed to be used for mesenchymal stem cell implantation in cartilage repair procedures, having controllable physicochemical properties such as porosity, mechanical strength, and permeability, and a unique self-sealing property. The membranes possess a bilayer structure with a less porous layer providing mechanical strength and selective permeability, exhibit an elastic modulus of between 0.3 and 0.9 MPa, and are permeable to molecules <40 kDa, which is in the range of cartilage permeability. Three different peptide ligands with the sequences Ac-GCGYGRGDSPG, Ac-GCG(OPG)4REGOFG(OPG)4, and Ac-GCG(OPG)7, respectively, are conjugated to the membranes and subject to in vitro cell adhesion and differentiation assays. Col I/Col II gene expression ratios indicated that the collagen-mimetic peptide, Ac-GCG(OPG)7, best supported mesenchymal stem cell differentiation into the chondrogenic lineage. Although low retention of the membrane is observed in vivo in a rabbit knee model, results suggest that the membrane was able to facilitate mesenchymal stem cell implantation and differentiation to chondrocytes. These PVA-based membranes provide a feasible, synthetic, off-the-shelf material for the delivery of stem cells, and can be modified for other surgical applications.

The influence of tissue microenvironment on stem cell-based cartilage repair

Mesenchymal stem/progenitor cells and induced pluripotent stem cells have become viable cell sources for prospective cell-based cartilage engineering and tissue repair. The development and function of stem cells are influenced by the tissue microenvironment. Specifically, the local tissue microenvironment can dictate how stem cells integrate into the existing tissue matrix and how successfully they can restore function to the damaged area in question. This review focuses on the microenvironmental features of articular cartilage and how they influence stem cell-based cartilage tissue repair. Also discussed are current tissue-engineering strategies used in combination with cell-based therapies, all of which are designed to mimic the natural properties of cartilage tissue in order to achieve a better healing response.

Comparison of Collagen Graft Fixation Methods in the Porcine Knee: Implications for Matrix-Assisted Chondrocyte Implantation and Second-Generation Autologous Chondrocyte Implantation

PURPOSE

To evaluate the fixation integrity at time zero of a type I/III collagen patch secured to a chondral defect in the porcine knee using methods typically employed in autologous chondrocyte implantation (ACI) and matrix-assisted chondrocyte implantation.

METHODS

Twenty-four porcine knee specimens underwent a medial parapatellar arthrotomy. A prefabricated template was used to create cartilage defects of 2 cm(2) in the medial femoral condyle. A size-matched collagen patch was fashioned. Four methods of fixation to the chondral defect were analyzed: group 1-saline, group 2-fibrin glue around the periphery of the patch, group 3-fibrin glue applied to the base of the defect and around the periphery of the patch, group 4-6-0 vicryl suture and fibrin glue around the periphery of the patch. Collagen patch fixation was assessed at intervals of 60, 300, 600, 900, and 1,200 cycles from full extension to 90° of flexion, performed manually without application of axial force. Patch fixation was evaluated by 2 independent observers using a customized scoring scale.

RESULTS

Mean peripheral detachment of the patch and chondral defect uncovering remained less than 25% for all groups. Area of defect uncovering was significantly increased in group 2 compared with group 4 after 900 and 1,200 cycles (P = .0014 and P = .0025, respectively). Fibrin glue applied to the base of the defect, or suturing of the patch, reduced deformation significantly after 900 cycles.

CONCLUSIONS

Suture increases the stability of fixation of a type I/III collagen patch to a chondral defect better than fibrin glue alone in the porcine knee after repetitive cycling, with respect to patch detachment and chondral defect uncovering. Application of fibrin glue to the base of the defect, or securing the patch with suture, decreases collagen patch deformation.

CLINICAL RELEVANCE

In cases where minimally invasive techniques do not allow suture fixation of the collagen patch, scaffold fixation may be compromised during articular motion protocols typically used after second- and third-generation ACI procedures.

Defect type, localization and marker gene expression determines early adverse events of matrix-associated autologous chondrocyte implantation

INTRODUCTION

Since the first description of autologous chondrocyte implantation (ACI) in 1994 different methods and improvements were established for this regenerative treatment option of large chondral defects. This study analyzes safety and short-term clinical results from characterized ACI using a collagen based biphasic scaffold and evaluates prognostic factors.

METHODS

433 patients with a mean age of 33.4 years and localized grade III to IV cartilage defects (ICRS classification) in the knee or ankle were included. Mean defect size was 5.9 cm(2). Prior seeding of the scaffold, expanded chondrocytes were characterized by RT-PCR on 6 different marker genes (type I and II collagen, aggrecan, interleukin-1 β (IL-1β), vascular endothelial growth factor receptor 1 (FLT-1) and bone sialoprotein-2 (BSP-2)). Clinical outcome was evaluated using a questionnaire for defect history, basic demographics, time elapsed from surgery, 10-point outcome assessments of pain, function and swelling. Moreover, adverse events (AEs) or subsequent treatments were recorded and analysed.

RESULTS

Patients improved significantly over baseline (p < 0.0001) in pain, function and swelling. Subjects with later than 12 months follow-up reported nominally greater mean changes. Graft failure incidence was 6% for patients with greater than one year follow-up. Graft-related complications were significantly higher for patellar (p < 0.0001) and degenerative defects (p = 0.005). Elevated expression of FLT-1 (p = 0.02) or IL-1 β mRNA (p = 0.03) was associated with graft-related AEs. A borderline association was found for low collagen type II expression (p = 0.08).

CONCLUSION

Early graft-related AEs after ACI with a biphasic collagen scaffold are related to defect type, location and marker gene expression. The levels of significance observed for gene expression with respect to graft-related AEs were subordinate to those identified in the analysis of lesion history and location.

Incidence, degree, and development of graft hypertrophy 24 months after matrix-induced autologous chondrocyte implantation: association with clinical outcomes

BACKGROUND

Graft hypertrophy is a common occurrence after periosteal, collagen-covered and matrix-induced autologous chondrocyte implantation (MACI).

PURPOSE/HYPOTHESIS

The purpose of this study was to investigate the incidence, development, and degree of graft hypertrophy at 24 months after MACI. The hypothesis was that graft hypertrophy would not be associated with clinical outcome at 24 months.

STUDY DESIGN

Case series, Level of evidence, 4.

METHODS

This study was undertaken in 180 consecutive patients (113 male, 67 female) after MACI in the knee. All patients were assessed clinically using the Knee injury and Osteoarthritis Outcome Score (KOOS) and underwent magnetic resonance imaging (MRI) at 3, 12, and 24 months after surgery. The incidence of hypertrophy relevant to anatomic graft site was investigated, as was the progressive change in hypertrophic studies postoperatively. The degree of tissue overgrowth in hypertrophic cases was investigated, as was its association with patient clinical outcome at 24 months after surgery.

RESULTS

Of the 180 patients, 50 demonstrated a hypertrophic graft at 1 or more postoperative time points. This included 9 grafts (5.0%) at 3 months and 32 grafts (18.7%) at 12 months. At 24 months, 47 grafts (26.1%)-43 (32.1%) tibiofemoral and 4 (8.7%) patellofemoral-were hypertrophic. Patients with hypertrophic grafts at 24 months (n = 47) were younger (P = .051), they had a lower body mass index (BMI; P = .069), and significantly fewer of them had patellofemoral grafts (P = .007) compared with patients who had grafts with full (100%) tissue infill (n = 61). There were no significant differences in any of the KOOS subscales between patients with graft hypertrophy or full (100%) tissue infill at 24 months after surgery, while the severity of graft hypertrophy was not associated with KOOS subscales at 24 months.

CONCLUSION

Hypertrophic grafts after MACI were common and continued to develop through to 24 months after surgery. Hypertrophic growth was associated with being younger and having a lower BMI, was more common on the femoral condyles, and overall was not associated with clinical outcome at 24 months after surgery. However, further research with longer term follow-up is required to evaluate the effect of persistent hypertrophy on graft stability and to assess the use of early surgical intervention to prevent such failure.

Improved quality of cartilage repair by bone marrow mesenchymal stem cells for treatment of an osteochondral defect in a cynomolgus macaque model

BACKGROUND AND PURPOSE

Integration of repaired cartilage with surrounding native cartilage is a major challenge for successful tissue-engineering strategies of cartilage repair. We investigated whether incorporation of mesenchymal stem cells (MSCs) into the collagen scaffold improves integration and repair of cartilage defects in a cynomolgus macaque model.

METHODS

Cynomolgus macaque bone marrow-derived MSCs were isolated and incorporated into type-I collagen gel. Full-thickness osteochondral defects (3 mm in diameter, 5 mm in depth) were created in the patellar groove of 36 knees of 18 macaques and were either left untreated (null group, n = 12), had collagen gel alone inserted (gel group, n = 12), or had collagen gel incorporating MSCs inserted (MSC group, n = 12). After 6, 12, and 24 weeks, the cartilage integration and tissue response were evaluated macroscopically and histologically (4 null, 4 gel, and 4 MSC knees at each time point).

RESULTS

The gel group showed most cartilage-rich reparative tissue covering the defect, owing to formation of excessive cartilage extruding though the insufficient subchondral bone. Despite the fact that a lower amount of new cartilage was produced, the MSC group had better-quality cartilage with regular surface, seamless integration with neighboring naïve cartilage, and reconstruction of trabecular subchondral bone.

INTERPRETATION

Even with intensive investigation, MSC-based cell therapy has not yet been established in experimental cartilage repair. Our model using cynomolgus macaques had optimized conditions, and the method using MSCs is superior to other experimental settings, allowing the possibility that the procedure might be introduced to future clinical practice.

Potential benefits and limitations of utilizing chondroprogenitors in cell-based cartilage therapy

Chondroprogenitor cells are a subpopulation of multipotent progenitors that are primed for chondrogenesis. They are believed to have the biological repertoire to be ideal for cell-based cartilage therapy. In addition to summarizing recent advances in chondroprogenitor cell characterization, this review discusses the projected pros and cons of utilizing chondroprogenitors in regenerative medicine and compares them with that of pre-existing methods, including autologous chondrocyte implantation (ACI) and the utilization of bone marrow derived mesenchymal stem cells (MSCs) for the purpose of cartilage tissue repair.

Graft hypertrophy of matrix-based autologous chondrocyte implantation: a two-year follow-up study of NOVOCART 3D implantation in the knee

PURPOSE

Graft hypertrophy is a major complication in the treatment for localized cartilage defects with autologous chondrocyte implantation (ACI) using periosteal flap and its further development, Novocart (a matrix-based ACI procedure). The aim of the present study is to investigate individual criteria for the development of graft hypertrophy by NOVOCART 3D implantation of the knee in the post-operative course of 2 years.

METHODS

Forty-one consecutive patients with 44 isolated cartilage defects of the knee were treated with NOVOCART 3D implants. Individual criteria and defect-associated criteria were collected. Follow-up MRIs were performed at 3, 6, 12 and 24 months. The NOVOCART 3D implants were measured and classified. The modified MOCART Score was used to evaluate quality and integration of the NOVOCART 3D implants in MRI.

RESULTS

Graft hypertrophy was observed in a total of 11 patients at all post-operative time points. We were able to show that NOVOCART 3D implantation of cartilage defects after acute trauma and osteochondritis dissecans (OCD) led to a significantly increased proportion of graft hypertrophy. No other individual criteria (age, gender, BMI) or defect-associated criteria (concomitant surgery, second-line treatment, defect size, fixation technique) showed any influence on the development of graft hypertrophy. The modified MOCART Score results revealed a significant post-operative improvement within 2 years.

CONCLUSION

The aetiology of cartilage defects appears to have a relevant influence for the development of graft hypertrophy. Patients, who were treated with NOVOCART 3D implants after an acute event (acute trauma or OCD), are especially at risk for developing a graft hypertrophy in the post-operative course of two years.

LEVEL OF EVIDENCE

Case series, Level IV.

Cell-based therapy improves function in adolescents and young adults with patellar osteochondritis dissecans

BACKGROUND

Recent advances have been made in using chondrocytes and other cell-based therapy to treat cartilage defects in adults. However, it is unclear whether these advances should be extended to the adolescent and young adult-aged patients.

QUESTIONS/PURPOSES

We assessed cell-based surgical therapy for patellar osteochondritis dissecans (OCD) in adolescents and young adults by (1) determining function with the International Knee Documentation Committee (IKDC) subjective and Lysholm-Gillquist scores; and (2) evaluating activity level using the Tegner-Lysholm scale.

METHODS

We retrospectively reviewed 23 patients between 12 and 21 years of age (mean 16.8 years) treated for OCD lesions involving the patella from 2001 to 2008. Twenty patients had autologous chondrocyte implantation and three patients had cultured bone marrow stem cell implantation. There were 19 males and four females. We obtained preoperative CT scans to assess patella subluxation, tilt, and congruence angle to determine choice of treatment. We obtained IKDC subjective knee evaluation scores, Tegner-Lysholm activity levels, and Lysholm-Gillquist knee scores preoperatively and at 6, 12, and 24 months postoperatively.

RESULTS

Mean IKDC score, Tegner-Lysholm outcomes, and Lysholm-Gillquist scale improved from 45, 2.5, and 50, respectively, at surgery to 75, 4, and 70, respectively, at 24-month followup. Complications include periosteal hypertrophy observed in two patients.

CONCLUSION

Cell-based therapy was associated with short-term improvement in function in adolescents and young adults with patellar OCD.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Comparing Responsiveness of Six Common Patient-Reported Outcomes to Changes Following Autologous Chondrocyte Implantation: A Systematic Review and Meta-Analysis of Prospective Studies

OBJECTIVE

To compare the responsiveness of six common patient-reported outcomes (PROs) following autologous chondrocyte implantation (ACI).

DESIGN

A systematic search was conducted to identify reports of PROs following ACI. Study quality was evaluated using the modified Coleman Methodology Score (mCMS). For each outcome score, pre- to postoperative paired Hedge's g effect sizes were calculated with 95% confidence intervals (CIs). Random effects meta-analyses were performed to provide a summary response for each PRO at time points (TP) I (<1 year), II (1 year to <2 years), III (2 years to <4 years), IV (≥4 years), and overall.

RESULTS

The mean mCMS for the 42 articles included was 50.9 ± 9.2. For all evaluated instruments, none of the mean effect size CIs encompassed zero. The International Knee Documentation Committee Subjective Knee Form (IKDC) had increasing responsiveness over time with TP-IV, demonstrating greater mean effect size [confidence interval] (1.78 [1.33, 2.24]) than TP-I (0.88 [0.69, 1.07]). The Knee Injury and Osteoarthritis Outcome Score-Sports and recreation subscale (KOOS-Sports) was more responsive at TP-III (1.76 [0.87, 2.64]) and TP-IV (0.98 [0.81, 1.15]) than TP-I (0.61 [0.44, 0.78]). Overall, the Medical Outcomes Study 36-Item Short Form Health Survey Physical Component Scale (0.60 [0.46, 0.74]) was least responsive. Both the Lysholm Scale (1.42 [1.14, 1.72]) and the IKDC (1.37 [1.13, 1.62]) appear more responsive than the KOOS-Sports (0.90 [0.73, 1.07]). All other KOOS subscales had overall effect sizes ranging from 0.90 (0.74, 1.22) (Symptoms) to 1.15 (0.76, 1.54) (Quality of Life).

CONCLUSIONS

All instruments were responsive to improvements in function following ACI. The Lysholm and IKDC were the most responsive instruments across time. IKDC and KOOS-Sports may be more responsive to long-term outcomes, especially among active individuals.

Overview of cartilage biology and new trends in cartilage stimulation

This article reviews the basics of articular cartilage biology, which provide a necessary foundation for understanding the evolving field of articular cartilage injury and repair. The currently popular treatment options for osteochondral injury (microfracture, osteochondral autograft transfer system, osteochondral allograft, autologous chondrocyte implantation, and the use of scaffolds with autologous chondrocyte implantation) document the significant advances made in this area in the past 2 decades. Integration of newly available information and technology derived from advances in molecular biology and tissue engineering holds even greater promise for continued advances in optimal management of this challenging problem.

The present state of treatments for articular cartilage defects in the knee

INTRODUCTION

Chondral and osteochondral lesions of the knee are notoriously difficult to treat due to the poor healing capacity of articular cartilage and the hostile environment of moving joints, ultimately causing disabling pain and early osteoarthritis. There are many different reconstructive techniques used currently but few are proven to be of value. However, some have been shown to produce a better repair with hyaline-like cartilage rather than fibrocartilage.

METHODS

A systematic search of all available online databases including PubMed, MEDLINE(®) and Embase™ was undertaken using several keywords. All the multiple treatment options and methods available were considered. These were summarised, and the evidence for and against them was scrutinised.

RESULTS

A total of 460 articles were identified after cross-referencing the database searches using the keywords. These revealed that autologous and matrix assisted chondrocyte implantation demonstrated both 'good to excellent' histological results and significant improvement in clinical outcomes.

CONCLUSIONS

Autologous and matrix assisted chondrocyte implantation have been shown to treat symptomatic lesions successfully with significant histological and clinical improvement. There is, however, still a need for further randomised clinical trials, perfecting the type of scaffold and the use of adjuncts such as growth factors. A list of recommendations for treatment and the potential future trends of managing these lesions are given.

Characterized chondrocyte implantation in the patellofemoral joint: an up to 4-year follow-up of a prospective cohort of 38 patients

BACKGROUND

Autologous chondrocyte implantation (ACI) is an accepted treatment option for selected condylar cartilage defects in the knee. Results for patellofemoral chondral defects have been less favorable.

HYPOTHESIS

Autologous chondrocyte implantation with characterized chondrocytes will result in clinically relevant improvement in patellofemoral lesions.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients with symptomatic patellofemoral full-thickness cartilage lesions were treated with ACI using characterized chondrocytes (ChondroCelect) covered with a collagen type I membrane. Clinical outcome was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and a visual analog scale (VAS) for pain. Responders were defined using 5 categories (≥10 points and ≥20%, 30%, 50%, 70%) based on the KOOS and VAS. Treatment failure was defined as partial loosening of more than 20% of the graft with subsequent procedures to the subchondral bone.

RESULTS

Thirty-eight patients, with a mean defect size of 4.89 cm(2) (range, 1.5-11 cm(2)), were treated for a patellar defect (n = 28), trochlear defect (n = 7), or a kissing lesion (trochlea and patella; n = 3). The minimum follow-up period was 24 months (mean, 37 months; range, 24-72 months). Treated patients showed statistically significant improvements in the KOOS (at 12, 18, 24, 36, and 48 months) and VAS (at the same time points) compared with pretreatment for each time point. Responder analysis identified approximately 84% of patients with a clinically relevant improvement greater than 10 points at 3 years. Treatment failure was observed in 5 patients. The most commonly reported adverse events were joint crepitation (n = 18) and arthrofibrosis (n = 7). No relationship could be found between clinical outcome and anatomic characteristics of the patellofemoral joint, lesion size and site, time since onset, or age. Nine patients required additional surgery: 6 because of persistent symptoms and 3 for hardware removal.

CONCLUSION

Characterized chondrocyte implantation resulted in statistically significant and clinically relevant improvement over time. These results add to the evidence demonstrating that ACI is a valuable cartilage repair technique for patellofemoral lesions.

Cost-effectiveness analysis of autologous chondrocyte implantation: a comparison of periosteal patch versus type I/III collagen membrane

BACKGROUND

Autologous chondrocyte implantation (ACI) involves the use of a periosteal patch (ACI-P) as a cover for transplanted chondrocytes. Theoretically, this periosteal patch provides mesenchymal stem cells and growth factors that encourage chondrocyte development/differentiation. However, there is a significant rate of graft hypertrophy with the use of periosteum compared with using a type I/III collagen patch (ACI-C). This type I/III collagen patch, although not approved by the United States Food and Drug Administration for ACI, has been used extensively in Europe and in an "off-label" nature in the United States as a cover during ACI.

PURPOSE

To examine the cost effectiveness of ACI and determine whether ACI-C is more cost effective than ACI-P.

STUDY DESIGN

Economic and decision analysis; Level of evidence, 2.

METHODS

Outcome data and complication rates from patients undergoing ACI (ACI-P and ACI-C) were derived from the best evidence in the literature. Costs were determined by examining the typical patient charges undergoing ACI at a local orthopaedic hospital. The costs, results, and complication rates were used to develop a decision analysis model comparing ACI-P to ACI-C.

RESULTS

The cost of ACI-P was $66,752 and for ACI-C was $66,939.50 ($187.50 difference). The cost per quality-adjusted life year (QALY) for ACI-P was $9466 compared with $9243 for ACI-C. Sensitivity analysis was performed regarding the additional cost of the type I/III collagen patch ($780) in ACI-C as well as the rate of graft hypertrophy after ACI-P (25%). This analysis revealed that the cost of the type I/III collagen patch would have to reach $1721, or the rate of graft hypertrophy after ACI-P reduced to almost 11%, before ACI-P became more cost effective than ACI-C.

CONCLUSION

This cost-effectiveness analysis reveals that, while both ACI-P and ACI-C are cost effective, ACI-C is slightly more cost effective than ACI-P. This is likely secondary to the significant rate of patch-related complications associated with ACI-P, which is significantly reduced with ACI-C. Although the model is very sensitive to differences in outcomes between ACI-P and ACI-C, there is no high-quality evidence to suggest that there is a significant difference between the two. Thus, ACI-P becomes more cost effective if the cost of the type I/III collagen membrane is significantly increased or if the rate of graft hypertrophy after ACI-P were to be markedly reduced.

Autologous chondrocyte implantation for knee cartilage injuries: moderate functional outcome and performance in patients with high-impact activities

Few studies have assessed the results of autologous chondrocyte implantation in patients with high-impact activities. The purpose of this study was to evaluate the early functional outcome and activity level after 2-stage autologous chondrocyte implantation in professional soldiers and athletes. Nineteen patients with an average age of 32.2 years were treated with autologous chondrocyte implantation and followed up for a minimum of 2 years. All patients except 2 had received previous arthroscopic treatment with debridement and/or microfracture. The mean size of the postdebridement defect was 6.54 cm2. Using Novocart technology (B. Braun-Tetec, Reutlingen, Germany), periosteal patch and matrix-assisted autologous chondrocyte implantation was sequentially performed with no randomization. The average subjective knee evaluation score and Lysholm score improved from 39.16 and 42.42, respectively, preoperatively to 62.4 and 69.4, respectively, at latest follow-up. Median Tegner activity score was 8.8 before injury, 3.8 preoperatively, and 6.15 at latest follow-up. Second-look arthroscopy was performed in 11 patients due to persistent pain, decreased range of movement, and mechanical symptoms. Six of 19 (31.5%) patients with professional or recreational athletic activities returned to preinjury levels of athletic performance.This study shows that mid-term results with autologous chondrocyte implantation in high-performance patients are not as good as have been reported with other similar technologies. Motivational issues during prolonged rehabilitation, multiple surgical interventions before autologous chondrocyte implantation, patient age, and large defects can potentially influence the outcome and overall performance in this selected group of patients.

The incidence and clinical relevance of graft hypertrophy after matrix-based autologous chondrocyte implantation

BACKGROUND

Graft hypertrophy is the most common complication of periosteal autologous chondrocyte implantation (p-ACI).

PURPOSE

The aim of this prospective study was to analyze the development, the incidence rate, and the persistence of graft hypertrophy after matrix-based autologous chondrocyte implantation (mb-ACI) in the knee joint within a 2-year postoperative course.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between 2004 and 2007, a total of 41 patients with 44 isolated cartilage defects of the knee were treated with the mb-ACI technique. The mean age of the patients was 35.8 years (standard deviation [SD], 11.3 years), and the mean body mass index was 25.9 (SD, 4.2; range, 19-35.3). The cartilage defects were arthroscopically classified as Outerbridge grades III and IV. The mean area of the cartilage defect measured 6.14 cm(2) (SD, 2.3 cm(2)). Postoperative clinical and magnetic resonance imaging (MRI) examinations were conducted at 3, 6, 12, and 24 months to analyze the incidence and course of the graft.

RESULTS

Graft hypertrophy developed in 25% of the patients treated with mb-ACI within a postoperative course of 1 year; 16% of the patients developed hypertrophy grade 2, and 9% developed hypertrophy grade 1. Graft hypertrophy occurred primarily in the first 12 months and regressed in most cases within 2 years. The International Knee Documentation Committee (IKDC) and visual analog scale (VAS) scores improved during the postoperative follow-up time of 2 years. There was no difference between the clinical results regarding the IKDC and VAS pain scores and the presence of graft hypertrophy.

CONCLUSION

The mb-ACI technique does not lead to graft hypertrophy requiring treatment as opposed to classic p-ACI. The frequency of occurrence of graft hypertrophy after p-ACI and mb-ACI is comparable. Graft hypertrophy can be considered as a temporary excessive growth of regenerative cartilage tissue rather than a true graft hypertrophy. It is therefore usually not a persistent or systematic complication in the treatment of circumscribed cartilage defects with mb-ACI.

Autologous chondrocyte implantation for treatment of cartilage defects of the knee: what predicts the need for reintervention?

BACKGROUND

Autologous chondrocyte implantation (ACI) is a well-established treatment option for isolated cartilage defects of the knee joint, providing satisfying outcome. However, cases of treatment failure with the need for surgical reintervention are reported; typical patient's individual and environmental risk factors have previously not been described.

HYPOTHESIS

The need for reintervention after ACI is associated with specific preoperative detectable individual risk factors.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 413 patients following ACI (first, second, and third generation) were filtered for those who required revision surgery during their follow-up time (2-11.8 years). Factors were analyzed that might have significant effects on increased revision rate. Using preoperatively collected data, all patients were grouped according to 12 standard prognostic factors. Apart from odds ratio and Pearson χ(2) test, statistical analysis of risk factors was performed with multivariate binary logistic regression models and Cox regression, the method of choice for survival time data.

RESULTS

After a follow-up of 4.4 ± 0.9 years (limited to 5 years), a total of 88 patients (21.3%) had undergone surgical revision. The time to revision surgery was 1.8 ± 1.1 years. Four prognostic factors associated with a significantly higher risk for reintervention were detected: (1) female gender (Cox survival fit: P = .033), (2) previous surgeries of the affected joint (P = .002), (3) previous bone marrow stimulation (P = .041), and (4) periosteum patch-covered ACI (P = .028). An influence of patient age, body mass index (BMI), defect number, defect size, lesion origin, lesion location, parallel treatment, or smoking on the risk for reintervention could not be observed.

CONCLUSION

The study identifies clear facts that significantly increase the risk of revision surgery. These facts can be easily obtained preoperatively and may be taken into consideration when indicating ACI.

Morphological and biochemical T2 evaluation of cartilage repair tissue based on a hybrid double echo at steady state (DESS-T2d) approach

PURPOSE

To use a new approach which provides, based on the widely used three-dimensional double-echo steady-state (DESS) sequence, in addition to the morphological information, the generation of biochemical T2 maps in one hybrid sequence.

MATERIALS AND METHODS

In 50 consecutive MRIs at 3.0 Tesla (T) after matrix-associated autologous chondrocyte transplantation (MACT) of the knee, by the use this new DESS-T2d approach, the morphological Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) score, as well as biochemical T2d values were assessed. Furthermore, these results were correlated to standard morphological sequences as well as to standard multi-echo spin-echo T2 mapping.

RESULTS

The MOCART score correlated (Pearson:0.945; P < 0.001) significantly as assessed with standard morphological sequences (68.8 ± 13.2) and the morphological images of the DESS T2d sequence (68.7 ± 12.6). T2 and T2d relaxation times (ms) were comparable in between the control cartilage (T2: 52.5 ± 11.4; T2d: 46.6 ± 10.3) and the repair tissue (T2: 54.4 ± 11.4; T2d: 47.5 ± 13.0) (T2: P = 0.157; T2d: P = 0.589). As expected, T2d values were lower than the standard-T2 values, however, both functional relaxation times correlated significantly (Pearson:0.429; P < 0.001).

CONCLUSION

The presented hybrid approach provides the possibility to combine morphological and biochemical MRI in one fast 3D sequence, and thus, may attract for the clinical use of biochemical MRI.

Failures, re-operations, and complications after autologous chondrocyte implantation--a systematic review

OBJECTIVE

To determine and compare failure, re-operation, and complication rates of all generations and techniques of autologous chondrocyte implantation (ACI).

METHODS

A systematic review of multiple medical databases was performed according to PRISMA guidelines. Levels I-IV evidence were included. Generations of ACI and complications after ACI were explicitly defined. All subject and defect demographic data were analyzed. Modified Coleman Methodology Scores (MCMSs) were calculated for all studies.

RESULTS

82 studies were identified for inclusion (5276 subjects were analyzed; 6080 defects). Ninety percent of the studies in this review were rated poor according to the MCMS. There were 305 failures overall (5.8% subjects; mean time to failure 22 months). Failure rate was highest with periosteal ACI (PACI). Failure rates after PACI, collagen-membrane cover ACI (CACI), second generation, and all-arthroscopic, second-generation ACI were 7.7%, 1.5%, 3.3%, and 0.83%, respectively. The failure rate of arthrotomy-based ACI was 6.1% vs 0.83% for all-arthroscopic ACI. Overall rate of re-operation was 33%. Re-operation rate after PACI, CACI, and second-generation ACI was 36%, 40%, and 18%, respectively. However, upon exclusion of planned second-look arthroscopy, re-operation rate was highest after PACI. Unplanned re-operation rates after PACI, CACI, second-generation, and all-arthroscopic second-generation ACI were 27%, 5%, 5%, and 1.4%, respectively. Low numbers of patients undergoing third-generation ACI precluded comparative analysis of this group.

CONCLUSIONS

Failure rate after all ACI generations is low (1.5-7.7%). Failure rate is highest with PACI, and lower with CACI and second-generation techniques. One out of three ACI patients underwent a re-operation. Unplanned re-operations are seen most often following PACI. Hypertrophy and delamination is most commonly seen after PACI. Arthrofibrosis is most commonly seen after arthrotomy-based ACI. Use of a collagen-membrane cover, second-generation techniques, and all-arthroscopic, second-generation approaches have reduced the failure, complication, and re-operation rate after ACI.

Advanced morphological 3D magnetic resonance observation of cartilage repair tissue (MOCART) scoring using a new isotropic 3D proton-density, turbo spin echo sequence with variable flip angle distribution (PD-SPACE) compared to an isotropic 3D steady-state free precession sequence (True-FISP) and standard 2D sequences

PURPOSE

To evaluate a new isotropic 3D proton-density, turbo-spin-echo sequence with variable flip-angle distribution (PD-SPACE) sequence compared to an isotropic 3D true-fast-imaging with steady-state-precession (True-FISP) sequence and 2D standard MR sequences with regard to the new 3D magnetic resonance observation of cartilage repair tissue (MOCART) score.

MATERIALS AND METHODS

Sixty consecutive MR scans on 37 patients (age: 32.8 ± 7.9 years) after matrix-associated autologous chondrocyte transplantation (MACT) of the knee were prospectively included. The 3D MOCART score was assessed using the standard 2D sequences and the multiplanar-reconstruction (MPR) of both isotropic sequences. Statistical, Bonferroni-corrected correlation as well as subjective quality analysis were performed.

RESULTS

The correlation of the different sequences was significant for the variables defect fill, cartilage interface, bone interface, surface, subchondral lamina, chondral osteophytes, and effusion (Pearson coefficients 0.514-0.865). Especially between the standard sequences and the 3D True-FISP sequence, the variables structure, signal intensity, subchondral bone, and bone marrow edema revealed lower, not significant, correlation values (0.242-0.383). Subjective quality was good for all sequences (P ≥ 0.05). Artifacts were most often visible on the 3D True-FISP sequence (P < 0.05).

CONCLUSION

Different isotropic sequences can be used for the 3D evaluation of cartilage repair with the benefits of isotropic 3D MRI, MPR, and a significantly reduced scan time, where the 3D PD-SPACE sequence reveals the best results.

Combined autologous chondrocyte implantation (ACI) with supra-condylar femoral varus osteotomy, following lateral growth-plate damage in an adolescent knee: 8-year follow-up

We report the 8-year clinical and radiographic outcome of an adolescent patient with a large osteochondral defect of the lateral femoral condyle, and ipsilateral genu valgum secondary to an epiphyseal injury, managed with autologous chondrocyte implantation (ACI) and supracondylar re-alignment femoral osteotomy. Long-term clinical success was achieved using this method, illustrating the effective use of re-alignment osteotomy in correcting mal-alignment of the knee, protecting the ACI graft site and providing the optimum environment for cartilage repair and regeneration. This is the first report of the combined use of ACI and femoral osteotomy for such a case.

Magnetic Resonance Imaging of Cartilage Repair: A Review

Articular cartilage lesions are a common pathology of the knee joint, and many patients may benefit from cartilage repair surgeries that offer the chance to avoid the development of osteoarthritis or delay its progression. Cartilage repair surgery, no matter the technique, requires a noninvasive, standardized, and high-quality longitudinal method to assess the structure of the repair tissue. This goal is best fulfilled by magnetic resonance imaging (MRI). The present article provides an overview of the current state of the art of MRI of cartilage repair. In the first 2 sections, preclinical and clinical MRI of cartilage repair tissue are described with a focus on morphological depiction of cartilage and the use of functional (biochemical) MR methodologies for the visualization of the ultrastructure of cartilage repair. In the third section, a short overview is provided on the regulatory issues of the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMEA) regarding MR follow-up studies of patients after cartilage repair surgeries.

The use of continuous passive motion following knee cartilage defect surgery: a systematic review

We evaluated the clinical evidence of using continuous passive motion postoperatively after treating articular cartilage lesions of the knee. We hypothesized that postoperatively, the use of continuous passive motion improves the outcomes of cartilage restoration procedures. Multiple medical databases (MEDLINE, EMBASE, CINAHL, PubMed, Sport-Discus, and Cochrane) were searched for Level I through IV evidence with specific study inclusion and exclusion criteria. The following key words were searched: microfracture, mosaicplasty, OATS, ACI, osteochondral autograft, osteochondral allograft, autologous chondrocyte implantation, autologous chondrocyte transplantation, CPM, continuous passive motion, motion therapy, postoperative knee rehabilitation, cartilage, knee. All studies were independently reviewed by the authors and the references were checked for any missed articles. Four Level III studies were identified that met inclusion criteria for our hypothesis. No randomized, controlled studies were identified. A meta-analysis could not be performed as a result of the heterogeneity of the procedures and outcome measures. Definitive conclusions regarding the benefits of continuous passive motion postoperatively in knee cartilage surgery could not be made secondary to this heterogeneity. Continuous passive motion is commonly used postoperatively following cartilage surgery. Unfortunately, the clinical evidence (only 4 studies) to support the use of continuous passive motion is lacking despite an overwhelming abundance of basic science support and the common clinical practice of continuous passive motion implementation postoperatively in knee cartilage restoration procedures. There is a great need for well-conducted, high-level evidence studies to address this void in our literature.

Articular Cartilage Injury in Athletes

Articular cartilage lesions in the athletic population are observed with increasing frequency and, due to limited intrinsic healing capacity, can lead to progressive pain and functional limitation over time. If left untreated, isolated cartilage lesions can lead to progressive chondropenia or global cartilage loss over time. A chondropenia curve is described to help predict the outcome of cartilage injury based on different lesion and patient characteristics. Nutriceuticals and chondroprotective agents are being investigated as tools to slow the development of chondropenia. Several operative techniques have been described for articular cartilage repair or replacement and, more recently, cartilage regeneration. Rehabilitation guidelines are being developed to meet the needs of these new techniques. Next-generation techniques are currently evaluated to optimize articular cartilage repair biology and to provide a repair cartilage tissue that can withstand the high mechanical loads experienced by the athlete with consistent long-term durability.

Variation of mesenchymal cells in polylactic acid scaffold in an osteochondral repair model

OBJECTIVE

To achieve osteochondral regeneration utilizing transplantation of cartilage-lineage cells and adequate scaffolds, it is essential to characterize the behavior of transplanted cells in the repair process. The objectives of this study were to elucidate the survival of mesenchymal cells (MCs). In a polylactic acid (PLA) scaffold and assess the possibility of MC/PLA constructs for osteochondral repair.

DESIGN

Bone marrow from mature male rabbits was cultured for 2 weeks, and fibroblast-like MCs, which contain mesenchymal stem cells (MSCs), were obtained. A cell/scaffold construct was prepared with one million MCs and a biodegradable PLA core using a rotator device. One week after culturing, the construct was transplanted into an osteochondral defect in the medial femoral condyle of female rabbits and the healing process examined histologically. To examine the survivability of transplanted MCs, the male-derived sex-determining region Y (SRY) gene was assessed as a marker of MCs in the defect by polymerase chain reaction (PCR).

RESULTS

In the groups of defects without any treatment, and the transplantation of PLA without cells, the defects were not repaired with hyaline cartilage. The cartilaginous matrix by safranin O staining and type II collagen by immunohistochemical staining were recognized, however the PLA matrix was still present in the defects at 24 weeks after transplantation of the construct. During the time passage, transplanted MCs numbers decreased from 7.8 x 105 at 1 week, to 3.5 x 105 at 4 weeks, and to 3.8 x 104 at 12 weeks. Transplanted MCs were not detectable at 24 weeks.

CONCLUSIONS

MCs contribute to the osteochondral repair expressing the cartilaginous matrix, however the number of MCs were decreasing with time (i.e. 24 weeks). These results could be essential for achieving cartilage regeneration by cell transplantation strategies with growth factors and/or gene therapy.

Pre- and postoperative assessment in joint preserving and replacing surgery

Advances in imaging technology have increased its suitability for diagnosing musculoskeletal disease. Modification of imaging techniques and improved image quality have led to increased use of computed tomography and magnetic resonance imaging in the assessment of postoperative complications. This article discusses the indications, pre- and postoperative imaging findings, and postoperative complications of knee and hip arthroplasty, articular cartilage repair, and high tibial osteotomy.

Three-dimensional magnetic resonance observation of cartilage repair tissue (MOCART) score assessed with an isotropic three-dimensional true fast imaging with steady-state precession sequence at 3.0 Tesla

INTRODUCTION

Cartilage defects are common pathologies and surgical cartilage repair shows promising results. In its postoperative evaluation, the magnetic resonance observation of cartilage repair tissue (MOCART) score, using different variables to describe the constitution of the cartilage repair tissue and the surrounding structures, is widely used. High-field magnetic resonance imaging (MRI) and 3-dimensional (3D) isotropic sequences may combine ideal preconditions to enhance the diagnostic performance of cartilage imaging.Aim of this study was to introduce an improved 3D MOCART score using the possibilities of an isotropic 3D true fast imaging with steady-state precession (True-FISP) sequence in the postoperative evaluation of patients after matrix-associated autologous chondrocyte transplantation (MACT) as well as to compare the results to the conventional 2D MOCART score using standard MR sequences.

MATERIAL AND METHODS

The study had approval by the local ethics commission. One hundred consecutive MR scans in 60 patients at standard follow-up intervals of 1, 3, 6, 12, 24, and 60 months after MACT of the knee joint were prospectively included. The mean follow-up interval of this cross-sectional evaluation was 21.4 +/- 20.6 months; the mean age of the patients was 35.8 +/- 9.4 years. MRI was performed at a 3.0 Tesla unit. All variables of the standard 2D MOCART score where part of the new 3D MOCART score. Furthermore, additional variables and options were included with the aims to use the capabilities of isotropic MRI, to include the results of recent studies, and to adapt to the needs of patients and physician in a clinical routine examination. A proton-density turbo spin-echo sequence, a T2-weighted dual fast spin-echo (dual-FSE) sequence, and a T1-weighted turbo inversion recovery magnitude (TIRM) sequence were used to assess the standard 2D MOCART score; an isotropic 3D-TrueFISP sequence was prepared to evaluate the new 3D MOCART score. All 9 variables of the 2D MOCART score were compared with the corresponding variables obtained by the 3D MOCART score using the Pearson correlation coefficient; additionally the subjective quality and possible artifacts of the MR sequences were analyzed.

RESULTS

The correlation between the standard 2D MOCART score and the new 3D MOCART showed for the 8 variables "defect fill," "cartilage interface," "surface," "adhesions," "structure," "signal intensity," "subchondral lamina," and "effusion"-a highly significant (P < 0.001) correlation with a Pearson coefficient between 0.566 and 0.932. The variable "bone marrow edema" correlated significantly (P < 0.05; Pearson coefficient: 0.257). The subjective quality of the 3 standard MR sequences was comparable to the isotropic 3D-TrueFISP sequence. Artifacts were more frequently visible within the 3D-TrueFISP sequence.

CONCLUSION

In the clinical routine follow-up after cartilage repair, the 3D MOCART score, assessed by only 1 high-resolution isotropic MR sequence, provides comparable information than the standard 2D MOCART score. Hence, the new 3D MOCART score has the potential to combine the information of the standard 2D MOCART score with the possible advantages of isotropic 3D MRI at high-field. A clear limitation of the 3D-TrueFISP sequence was the high number of artifacts. Future studies have to prove the clinical benefits of a 3D MOCART score.

Use of a type I/III bilayer collagen membrane decreases reoperation rates for symptomatic hypertrophy after autologous chondrocyte implantation

BACKGROUND

Autologous chondrocyte implantation is associated with a high rate of reoperation, mostly due to hypertrophy of the periosteal patch. European studies investigating the use of collagen membranes as a periosteal substitute report significant decreases in reoperation rates to less than 5%. This multicenter study investigates the off-label use of 1 collagen membrane as a periosteal substitute for autologous chondrocyte implantation.

HYPOTHESIS

The use of a collagen membrane for autologous chondrocyte implantation will decrease reoperation rates for hypertrophy with comparable rates of failure.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A multicenter cohort of 300 patients treated with periosteal-covered autologous chondrocyte implantation was compared with a consecutive series of 101 patients who underwent collagen membrane-covered autologous chondrocyte implantation with the Bio-Gide membrane by the same group of surgeons. The 1-year hypertrophy-related reoperation rates and overall failure rates of autologous chondrocyte implantation were evaluated in both groups.

RESULTS

Both groups were comparable for age (periosteal autologous chondrocyte implantation, 31.9 years; collagen autologous chondrocyte implantation, 32.4 years; P = .8) and average defect size (4.6 cm(2) and 4.7 cm(2), respectively; P = .7). The average number of defects (1.5 and 1.8; P = .001) and total defect area per knee (6.7 cm(2) and 8.6 cm(2); P = .003) were larger in the collagen membrane group. Within 1 year of surgery, 25.7% of patients treated with periosteal-covered autologous chondrocyte implantation required reoperation for hypertrophy and 2.3% were considered to have failed their treatment with autologous chondrocyte implantation. In comparison, only 5% of patients required reoperation for hypertrophy after collagen membrane-covered autologous chondrocyte implantation, and 4% were considered treatment failures.

CONCLUSION

The use of a collagen membrane for autologous chondrocyte implantation decreased the reoperation rate for hypertrophy after autologous chondrocyte implantation from 25.7% to 5% (P < .0001). Overall 1-year failure rates were comparable between the groups (P = .2). Even though the use of a collagen membrane for autologous chondrocyte implantation constitutes an off-label indication, its application appears justified by the lower morbidity to patients and decreased cost to the health care system. A detailed discussion with the patient is required regarding the use of an off-label device.

An overview of autologous chondrocyte implantation

Chondral damage to the knee is common and, if left untreated, can proceed to degenerative osteoarthritis. In symptomatic patients established methods of management rely on the formation of fibrocartilage which has poor resistance to shear forces. The formation of hyaline or hyaline-like cartilage may be induced by implanting autologous, cultured chondrocytes into the chondral or osteochondral defect.

Autologous chondrocyte implantation may be used for full-thickness chondral or osteochondral injuries which are painful and debilitating with the aim of replacing damaged cartilage with hyaline or hyaline-like cartilage, leading to improved function. The intermediate and long-term functional and clinical results are promising.

We provide a review of autologous chondrocyte implantation and describe our experience with the technique at our institution with a mean follow-up of 32 months (1 to 9 years).

The procedure is shown to offer statistically significant improvement with advantages over other methods of management of chondral defects.