[Clinical results after three years use of matrix-associated ACT for the treatment of osteochondral defects of the knee]

Sandwich Technique for Large Osteochondral Lesions of the Knee

OBJECTIVE

To evaluate whether a sandwich technique procedure for large osteochondral lesions (OCL) of the medial femur condyle reduces clinical symptoms and improves activity level as well as to assess repair tissue integration on MRI over 2 years.

DESIGN

Twenty-one patients (median age: 29 years, 18-44 years) who received matrix-associated autologous chondrocyte transplantation (MACT) combined with cancellous bone grafting at the medial femur condyle in a 1-step procedure were prospectively included. Patients were evaluated before surgery (baseline) as well as 3, 6, 12, and 24 months postoperatively, including clinical evaluation, Lysholm score, Tegner Activity Rating Scale, and MRI with Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score and a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS).

RESULTS

Seventeen patients were available for the 24-month (final) follow-up (4 dropouts). Lysholm significantly improved from 48 preoperatively stepwise to 95 at final follow-up (P < 0.05). Tegner improvement from 2.5 at baseline to 4.0 at final follow-up was not significant (P = 1.0). MOCART score improved significantly and stepwise from 65 at 3 months to 90 at 24 months (P < 0.05). Total WORMS improved from 14.5 at surgery to 7.0 after 24 months (P < 0.05). Body mass index and defect size at surgery correlated with total WORMS at final follow-up (P < 0.05) but did not correlate with clinical scores or defect filling.

CONCLUSION

MACT combined with cancellous bone grafting at the medial femoral condyle reduces symptoms continuously over 2 years. A 1-step procedure may reduce perioperative morbidity. However, despite improvements, patients' activity levels remain low, even 2 years after surgery.

Evolution of hydrogels for cartilage tissue engineering of the knee: A systematic review and meta-analysis of clinical studies

INTRODUCTION

In recent years, studies have boosted our knowledge about the biology and disorders of articular cartilage. In this regard, the design of hydrogel-based scaffolds has advanced to improve cartilage repair. However, the efficacy of knee cartilage repair using hydrogels remains unclear. The aim of systematic review and meta-analysis was to scrutinize the efficiency of hydrogel-based therapy in correcting cartilage defects of knee (femoral condyle, patella, tibia plateau and trochlea).

METHODS

The search was conducted in PubMed to gather articles published from 2004/1/1 to 2019/10/01, addressing the effects of implant of hydrogel on knee joint cartilage regeneration. The Cochrane Collaboration's tool for estimating the risk of bias was applied to check the quality of articles. The clinical data for meta-analysis was recorded using the visual analog scale (VAS), Lysholm score, WOMAC, and IKDC. The guidelines of Cochrane Handbook for Systematic Reviews of Interventions were utilized to conduct the review and meta-analysis in the RevMan 5.3 software.

RESULTS

The search resulted in 50 clinical trials that included 2846 patients, 986 of whom received cell-based hydrogel implants while 1860 patients used hydrogel without cell. There were significant differences comparing the pain scores based on the VAS (MD: -2.97; 95% CI: -3.15 to -2.79, P<0.00001) and WOMAC (MD: -25.22; 95% CI: -31.22 to -19.22, P<0.00001) between pre- and post-treatment with hydrogels. Furthermore, there were significant improvements in the functional scores based on the IKDC total score (MD: 30.67; P<0.00001) and the Lysholm knee scale (MD: 29.26; 95% CI: 26.74 to 31.78, P<0.00001). According to the Lysholm and IKDC score and after cumulative functional analysis, there was a significant improvement in this parameter (MD: 29.25; 95% CI: 27.26 to 31.25, P<0.00001).

CONCLUSIONS

This meta-analysis indicated clinically and statistically significant improvements in the pain score (VAS and WOMAC) and the functional score (IKDC and Lysholm) after the administration of hydrogel compared to pretreatment status. So, the current evidence shows the efficiency of hydrogel-based therapy in correcting and repairing knee cartilage defects.

In Vitro Analysis of Cartilage Regeneration Using a Collagen Type I Hydrogel (CaReS) in the Bovine Cartilage Punch Model

OBJECTIVE

Limitations of matrix-assisted autologous chondrocyte implantation to regenerate functional hyaline cartilage demand a better understanding of the underlying cellular/molecular processes. Thus, the regenerative capacity of a clinically approved hydrogel collagen type I implant was tested in a standardized bovine cartilage punch model.

METHODS

Cartilage rings (outer diameter 6 mm; inner defect diameter 2 mm) were prepared from the bovine trochlear groove. Collagen implants (± bovine chondrocytes) were placed inside the cartilage rings and cultured up to 12 weeks. Cartilage-implant constructs were analyzed by histology (hematoxylin/eosin; safranin O), immunohistology (aggrecan, collagens 1 and 2), and for protein content, RNA expression, and implant push-out force.

RESULTS

Cartilage-implant constructs revealed vital morphology, preserved matrix integrity throughout culture, progressive, but slight proteoglycan loss from the "host" cartilage or its surface and decreasing proteoglycan release into the culture supernatant. In contrast, collagen 2 and 1 content of cartilage and cartilage-implant interface was approximately constant over time. Cell-free and cell-loaded implants showed (1) cell migration onto/into the implant, (2) progressive deposition of aggrecan and constant levels of collagens 1 and 2, (3) progressively increased mRNA levels for aggrecan and collagen 2, and (4) significantly augmented push-out forces over time. Cell-loaded implants displayed a significantly earlier and more long-lasting deposition of aggrecan, as well as tendentially higher push-out forces.

CONCLUSION

Preserved tissue integrity and progressively increasing cartilage differentiation and push-out forces for up to 12 weeks of cultivation suggest initial cartilage regeneration and lateral bonding of the implant in this in vitro model for cartilage replacement materials.

Treatment of osteochondral defects with a combination of bone grafting and AMIC technique

INTRODUCTION

Osteochondral defects of the knee may cause functional impairment of young and sportively active patients. Different surgical treatment options have been proposed using either one or two step procedures. The aim of the current study was to evaluate mid-term outcomes of combined bone grafting with autologous matrix-associated chondrogenesis (AMIC) for the treatment of large osteochondral defects.

MATERIALS AND METHODS

15 Patients with osteochondrosis dissecans of the medial femoral condyle grade III or IV according to ICRS classification were treated with a single step surgical procedure combining bone grafting and the AMIC procedure. Mean defect size was 4.98 cm² (± 3.02) and patients were examined at 6, 12 weeks, 6 and 12 month and at mean final follow-up of 49 months (36-61). Patients were evaluated using VAS, IKDC, KOOS, Lysholm, Tegner activity scores and psychological and physical health assessed using the SF 12. MRI evaluation was performed at final follow-up using the MOCART score.

RESULTS

Pain had significantly decreased at final follow-up (7.2 ± 1.4 vs. 2.4 ± 2.6) compared to preoperative baseline. All functional scores had improved significantly throughout the follow-up period (IKDC from 36.6 ± 20.6 vs. 72.2 ± 18.7; KOOS 50.0 ± 18.9 vs. 81.7 ± 13.9; LYSHOLM 39.3 ± 19.5 vs. 79.8 ± 15.1). SF12 evaluation showed a significant increase in physical component summary (PCS) (31.2 ± 11.1 preoperative vs. 46.3 ± 9.9 at final follow-up), while mental component summary (MCS) remained stable (51.8 ± 8.9 vs. 57.3 ± 3.3). MOCART score revealed a mean overall score of 77 ± 15 at final follow-up. Integration to the adjacent cartilage was complete in 79%, incomplete in 21%. Defect filling was complete in 64%, incomplete in 36%.

CONCLUSION

Significant improvement of knee function and restoration of homogenous cartilage morphology could be achieved with simultaneous AMIC procedure and bone grafting in 2/3 of all patients with large osteochondral lesions at 4 years postoperatively.

Treatment of Knee Osteochondritis Dissecans With a Cell-Free Biomimetic Osteochondral Scaffold: Clinical and Imaging Findings at Midterm Follow-up

BACKGROUND

Osteochondritis dissecans (OCD) is a developmental condition of subchondral bone that may result in secondary separation and instability of the overlying articular cartilage, which in turn may lead to degeneration of the overall joint and early osteoarthritis. Biphasic scaffolds have been developed to address defects of the entire osteochondral unit by reproducing the different biological and functional requirements and guiding the growth of both bone and cartilage.

PURPOSE

To evaluate midterm clinical and imaging results after cell-free osteochondral scaffold implantation for the treatment of knee OCD.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-seven patients (8 women, 19 men; mean age, 25.5 ± 7.7 years) were treated for knee OCD, with International Cartilage Repair Society (ICRS) grade 3 to 4 lesions with a mean size of 3.4 ± 2.2 cm² (range, 1.5-12 cm²), and prospectively evaluated for up to 5 years using the ICRS classification system and the Tegner score. Eighteen patients underwent magnetic resonance imaging (MRI) at 24 and 60 months of follow-up, and the graft was evaluated using the magnetic resonance observation of cartilage repair tissue (MOCART) score for the cartilage layer, while a specific score was used for subchondral bone.

RESULTS

All patients significantly improved their clinical scores at each follow-up until their final evaluation. The mean International Knee Documentation Committee (IKDC) subjective score improved from 48.4 ± 17.8 to 82.2 ± 12.2 at 2 years ( P < .0005), and it then remained stable for up to 5 years postoperatively (90.1 ± 12.0). The mean Tegner score increased from 2.4 ± 1.7 preoperatively to 4.4 ± 1.6 at 2 years ( P = .001), with a further increase up to 5.0 ± 1.7 at 5 years of follow-up ( P < .0005 vs preoperatively), reaching almost the preinjury level (5.7 ± 2.2). The MOCART score showed stable results between 24 and 60 months, whereas the subchondral bone status significantly improved over time. No correlation was found between MRI findings and clinical outcomes.

CONCLUSION

This 1-step cell-free scaffold implantation procedure showed good and stable results for up to 60 months of follow-up for the treatment of knee OCD. MRI showed abnormalities, in particular at the subchondral bone level, but there was an overall improvement of features over time. No correlation was found between imaging and clinical findings.

Seaweed polysaccharide-based hydrogels used for the regeneration of articular cartilage

This manuscript provides an overview of the in vitro and in vivo studies reported in the literature focusing on seaweed polysaccharides based hydrogels that have been proposed for applications in regenerative medicine, particularly, in the field of cartilage tissue engineering. For a better understanding of the main requisites for these specific applications, the main aspects of the native cartilage structure, as well as recognized diseases that affect this tissue are briefly described. Current available treatments are also presented to emphasize the need for alternative techniques. The following part of this review is centered on the description of the general characteristics of algae polysaccharides, as well as relevant properties required for designing hydrogels for cartilage tissue engineering purposes. An in-depth overview of the most well known seaweed polysaccharide, namely agarose, alginate, carrageenan and ulvan biopolymeric gels, that have been proposed for engineering cartilage is also provided. Finally, this review describes and summarizes the translational aspect for the clinical application of alternative systems emphasizing the importance of cryopreservation and the commercial products currently available for cartilage treatment.

Autologous Bone Plug Supplemented With Autologous Chondrocyte Implantation in Osteochondral Defects of the Knee

BACKGROUND

Structural and functional outcome of bone graft with first- or second-generation autologous chondrocyte implantation (ACI) in treating cartilage and subchondral bone defect has not been reported previously.

PURPOSE

To evaluate the outcome of simultaneous transplantation of an autologous bone plug with first- or second-generation ACI for restoration of concomitant subchondral bone and full-thickness cartilage defect in the femoral condyle of the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Seventeen patients (mean ± SD age, 27 ± 7 years; range, 17-40 years)-12 with osteochondritis dissecans (International Cartilage Repair Society [ICRS] grades 3 and 4) and 5 with an isolated osteochondral defect (ICRS grade 4)-had the defect reconstructed with implantation of a unicortical autologous bone graft combined with ACI (the OsPlug technique). Functional outcome was assessed with Lysholm scores obtained preoperatively and at 1 and 5 years postoperatively. The repair site was evaluated with the Oswestry Arthroscopy Score (OAS), MOCART score (magnetic resonance observation of cartilage repair tissue), and ICRS II histology score. Formation of a subchondral lamina and lateral integration of the bone grafts were evaluated from magnetic resonance imaging scans.

RESULTS

The mean defect size was 4.5 ± 2.6 cm(2) (range, 1-9 cm(2)), and the mean depth was 11.3 ± 5 mm (range, 5-18 mm). The preoperative Lysholm score improved from 45 (interquartile range [IQR], 24; range, 16-79) to 77 (IQR, 28; range, 41-100) at 1 year (P = .001) and 70 (IQR, 35; range, 33-91) at 5 years (P = .009). The mean OAS of the repair site was 6.2 (range, 0-9) at a mean of 1.3 years. The mean MOCART score was 61 ± 22 (range, 20-85) at 2.6 ± 1.8 years. Histology demonstrated generally good integration of the repair cartilage with the underlying bone. Poor lateral integration of the bone graft, as assessed on magnetic resonance imaging scan, and a low OAS were significantly associated with a poor Lysholm score and failure. A total of 3 patients had treatment failure, with 1 requiring total knee replacement at 5 years (Lysholm score of 33 at failure) and the other 2 requiring further surgical intervention because of persistent symptoms at 2 and 4 years, respectively (both had Lysholm score of 45 at failure). The Lysholm score in these patients before failure were still noted to be higher than at the preoperative level.

CONCLUSION

The OsPlug technique shows significant improvement of functional outcome for up to 5 years in patients with high-grade osteochondritis dissecans or osteochondral defect. This is the first report describing association of bone graft integration with functional outcome after such a procedure. It also demonstrates histologic evidence of integration of the repair cartilage with the underlying bone graft.

Evolution of autologous chondrocyte repair and comparison to other cartilage repair techniques

Articular cartilage defects have been addressed using microfracture, abrasion chondroplasty, or osteochondral grafting, but these strategies do not generate tissue that adequately recapitulates native cartilage. During the past 25 years, promising new strategies using assorted scaffolds and cell sources to induce chondrocyte expansion have emerged. We reviewed the evolution of autologous chondrocyte implantation and compared it to other cartilage repair techniques. Methods. We searched PubMed from 1949 to 2014 for the keywords “autologous chondrocyte implantation” (ACI) and “cartilage repair” in clinical trials, meta-analyses, and review articles. We analyzed these articles, their bibliographies, our experience, and cartilage regeneration textbooks. Results. Microfracture, abrasion chondroplasty, osteochondral grafting, ACI, and autologous matrix-induced chondrogenesis are distinguishable by cell source (including chondrocytes and stem cells) and associated scaffolds (natural or synthetic, hydrogels or membranes). ACI seems to be as good as, if not better than, microfracture for repairing large chondral defects in a young patient's knee as evaluated by multiple clinical indices and the quality of regenerated tissue. Conclusion. Although there is not enough evidence to determine the best repair technique, ACI is the most established cell-based treatment for full-thickness chondral defects in young patients.

Reconstruction of osteochondral defects by combined bone grafting and a bilayer collagen membrane as a sandwich technique

Treatment of osteochondral lesions of the knee remains a major challenge in orthopedic surgery. Recently established procedures like autologous chondrocyte implantation or matrix-associated chondrocyte implantation yield good results, but include the disadvantage of two-step procedures. The purpose of this study was to evaluate the clinical and magnetic resonance imaging outcome of repairs of osteochondral defects of the knee by a combined procedure of bone grafting and covering with a bilayer collagen membrane in a sandwich technique. Seven male patients with a mean age of 42 (range 30-55) years and symptomatic focal osteochondral lesions of the knee grade IV according to the International Cartilage Repair Society classification were included. The mean diameter of defects was 28.6 (range 15-40) mm. Results were evaluated at a minimum of 24 months after surgery by International Knee Documentation Committee score, Lysholm-score, visual analogue scale, and magnetic resonance imaging with specific cartilage sequences, evaluating the ICRS score and the Magnetic Observation of Cartilage Repair Tissue (MOCART) score. All patients judged the operation as successful. Among the patients available for the long-term follow-up, mean visual analogue scale value was 1.3 (range 0-3) out of 10 points. Mean International Knee Documentation Committee score was 80.8 (range 63.2-88.5) out of 100 points. Mean Lysholm score was 85 (range 55-95) out of 100 points. None of the patients had to be reoperated until today. Evaluation of magnetic resonance imaging using the MOCART score revealed a good correlation to the clinical outcome. This is the first study reporting results after reconstruction of osteochondral defects of the knee joint by bone grafting and a bilayer collagen membrane. This new method offers the advantage of a one-step-procedure and yields both good clinical and magnetic resonance findings. We conclude that this procedure can be a valuable tool to improve joint function after osteochondral defects, trauma, and in joints with local arthritic lesions.

Treatment of knee osteochondritis dissecans with a cell-free biomimetic osteochondral scaffold: clinical and imaging evaluation at 2-year follow-up

BACKGROUND

Osteochondritis dissecans (OCD) is an acquired lesion of the subchondral bone that may result in separation and instability of the overlying articular cartilage. Unstable lesions must be treated surgically to reestablish the joint surface as anatomically as possible. Hypothesis/

PURPOSE

The aim of this study was to evaluate the potential of a biomimetic osteochondral scaffold to treat OCD by analyzing the results obtained at 2-year follow-up. The hypothesis was that this scaffold, which was developed to treat the entire osteochondral unit, might restore the articular surface and improve symptoms and function in patients affected by knee OCD.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-seven consecutive patients (19 men, 8 women; age [mean ± SD], 25.5 ± 7.7 years) who were affected by symptomatic knee OCD of the femoral condyles (average defect size 3.4 ± 2.2 cm(2)), grade 3 or 4 on the International Cartilage Repair Society (ICRS) scale, were enrolled and treated with the implantation of a 3-layer collagen-hydroxyapatite scaffold. Patients were prospectively evaluated by subjective and objective International Knee Documentation Committee (IKDC) and Tegner scores preoperatively and at 1- and 2-year follow-up. An MRI was also performed at the 2 follow-up times.

RESULTS

A statistically significant improvement in all clinical scores was obtained at 1 year, and a further improvement was found the following year. At the 2-year follow-up, the IKDC subjective score had increased from 48.4 ± 17.8 preoperatively to 82.3 ± 12.2, the IKDC objective evaluation from 40% to 85% of normal knees, and the Tegner score from 2.4 ± 1.7 to 4.5 ± 1.6. The MRI evaluations showed good defect filling and implant integration but also inhomogeneous regenerated tissue and subchondral bone changes in most patients at both follow-up times. No correlation between the MOCART (magnetic resonance observation of cartilage repair tissue) score and clinical outcome was found.

CONCLUSION

This biomimetic osteochondral scaffold seems to be a valid treatment option for knee OCD, showing a good clinical outcome at 2-year follow-up. Moreover, the improvement was not correlated with lesion size, so large lesions can benefit from this implant. Less favorable findings were obtained with MRI evaluation.

Arthroscopic second generation autologous chondrocytes implantation associated with bone grafting for the treatment of knee osteochondritis dissecans: Results at 6 years

PURPOSE

The aim of this study was to analyze the clinical outcome obtained with arthroscopic second generation autologous chondrocyte implantation (ACI) associated with bone grafting for the treatment of knee osteochondritis dissecans (OCD) at medium term follow-up.

METHODS

Thirty-four knees affected by symptomatic OCD grade III or IV on the ICRS (International Cartilage Repair Society) scale were treated and prospectively evaluated at 12, 24 months of follow-up, and at a final mean 6 ± 1 years of follow-up. The mean age at treatment was 21 ± 6 years. The average size of the defects was 3 ± 1cm(2). Patients were evaluated with IKDC, EQ-VAS, and Tegner scores.

RESULTS

A statistically significant improvement in all scores was observed after the treatment. The IKDC subjective score improved from 38 ± 13 to 81 ± 20, and 91% of the knees were rated as normal or nearly normal in the objective IKDC at the final evaluation. EQ-VAS and Tegner scores showed a statistically significant linear trend of improvement over time passing from 52 ± 18 to 83 ± 14 and from 2 ± 1 to 5 ± 3, respectively, at 6 years' follow-up. A better outcome was obtained in men, sport active patients, and smaller lesions.

CONCLUSIONS

Second generation ACI associated with bone grafting is a valid treatment option for knee OCD and may offer a good and stable clinical outcome at mean 6 years of follow-up. Further studies are needed to confirm the results over time, and determine if there is only a symptomatic improvement, or if this procedure may also prevent or delay further knee degeneration.

Tissue engineering approaches for osteoarthritis

With the ageing of the population and the major advances in targeted drug treatments, there is in medicine a shift in attention from survival towards quality of life. Therefore new challenges are emerging in modern health care. Preventive and personalized medicine have been identified as key steps in this context. New targeted biologicals for musculoskeletal diseases such as chronic arthritis have entered daily clinical practice, thereby not only controlling symptoms and signs, inflammation and destruction, but also maintaining function of the joints. The last aspect is essential for the independence of the individual and critical for the quality of life. Since the lifespan of prosthetic devices will always remain limited, new treatment approaches to repair skeletal structures need to be devised for the young and middle aged individuals with skeletal and joint damage caused by either congenital, traumatic, or inflammatory conditions. It is believed that regenerative medicine and more specifically tissue engineering may fill this void to some extent. Indeed, recent cellular therapeutics and combination products, now resorting under a new regulatory class of Advanced Medicinal Therapeutic Products, provide indications that progress is being made with clinically relevant outcomes in well-defined patient populations. For osteoarthritis, a joint disease leading to joint decompensation, novel tissue engineering therapies are being explored and, although most of the developments are still in early phase clinical studies, there are sufficient positive signals to pursue these novel therapeutic approaches in clinics. This article is part of a Special Issue entitled "Osteoarthritis".

Cell Seeding Densities in Autologous Chondrocyte Implantation Techniques for Cartilage Repair

Cartilage repair techniques have been among the most intensively investigated treatments in orthopedics for the past decade, and several different treatment modalities are currently available. Despite the extensive research effort within this field, the generation of hyaline cartilage remains a considerable challenge. There are many parameters attendant to each of the cartilage repair techniques that can affect the amount and types of reparative tissue generated in the cartilage defect, and some of the most fundamental of these parameters have yet to be fully investigated. For procedures in which in vitro-cultured autologous chondrocytes are implanted under a periosteal or synthetic membrane cover, or seeded onto a porous membrane or scaffold, little is known about how the number of cells affects the clinical outcome. Few published clinical studies address the cell seeding density that was employed. The principal objective of this review is to provide an overview of the cell seeding densities used in cell-based treatments currently available in the clinic for cartilage repair. Select preclinical studies that have informed the use of specific cell seeding densities in the clinic are also discussed.

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.

Cell transplantation for articular cartilage defects: principles of past, present, and future practice

As articular cartilage has very limited self-repair capability, the repair and regeneration of damaged cartilage is a major challenge. This review aims to outline the past, present, and future of cell therapies for articular cartilage defect repair. Autologous chondrocyte implantation (ACI) has been used clinically for more than 20 years, and the short, medium, and long-term clinical outcomes of three generation of ACI are extensively overviewed. Also, strategies of clinical outcome evaluation, ACI limitations, and the comparison of ACI clinical outcomes with those of other surgical techniques are discussed. Moreover, mesenchymal stem cells and pluripotent stem cells for cartilage regeneration in vitro, in vivo, and in a few clinical studies are reviewed. This review not only comprehensively analyzes the ACI clinical data but also considers the findings from state-of-the-art stem cell research on cartilage repair from bench and bedside. The conclusion provides clues for the future development of strategies for cartilage regeneration.

Evaluation of cartilage repair tissue after matrix-associated autologous chondrocyte transplantation using a hyaluronic-based or a collagen-based scaffold with morphological MOCART scoring and biochemical T2 mapping: preliminary results

BACKGROUND

In cartilage repair, bioregenerative approaches using tissue engineering techniques have tried to achieve a close resemblance to hyaline cartilage, which might be visualized using advanced magnetic resonance imaging.

PURPOSE

To compare cartilage repair tissue at the femoral condyle noninvasively after matrix-associated autologous chondrocyte transplantation using Hyalograft C, a hyaluronic-based scaffold, to cartilage repair tissue after transplantation using CaReS, a collagen-based scaffold, with magnetic resonance imaging using morphologic scoring and T2 mapping.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Twenty patients after matrix-associated autologous chondrocyte transplantation (Hyalograft C, n = 10; CaReS, n = 10) underwent 3-T magnetic resonance imaging 24 months after surgery. Groups were matched by age and defect size/localization. For clinical outcome, the Brittberg score was assessed. Morphologic analysis was applied using the magnetic resonance observation of cartilage repair tissue score, and global and zonal biochemical T2 mapping was performed to reflect biomechanical properties with regard to collagen matrix/content and hydration.

RESULTS

The clinical outcome was comparable in each group. The magnetic resonance observation of cartilage repair tissue score showed slightly but not significantly (P= .210) better results in the CaReS group (76.5) compared to the Hyalograft C group (70.0), with significantly better (P= .004) constitution of the surface of the repair tissue in the CaReS group. Global T2 relaxation times (milliseconds) for healthy surrounding cartilage were comparable in both groups (Hyalograft C, 49.9; CaReS, 51.9; P= .398), whereas cartilage repair tissue showed significantly higher results in the CaReS group (Hyalograft C, 48.2; CaReS, 55.5; P= .011). Zonal evaluation showed no significant differences (P > or = .05).

CONCLUSION

Most morphologic parameters provided comparable results for both repair tissues. However, differences in the surface and higher T2 values for the cartilage repair tissue that was based on a collagen scaffold (CaReS), compared to the hyaluronic-based scaffold, indicated differences in the composition of the repair tissue even 2 years postimplantation.

CLINICAL RELEVANCE

In the follow-up of cartilage repair procedures using matrix-associated autologous chondrocyte transplantation, differences due to scaffolds have to be taken into account.

Matrix-assisted autologous chondrocyte transplantation for the repair of cartilage defects of the knee: systematic clinical data review and study quality analysis

BACKGROUND

The clinical application of the second-generation tissue-engineering approach for the treatment of cartilage lesions has been documented for different types of scaffolds, but systematic information on clinical efficacy and long-term results is not available.

PURPOSE

To analyze and assess the quality of clinical studies on different products in the emerging field of matrix-assisted autologous chondrocyte transplantation. The secondary purpose of this review was to improve the quality assessment of studies by modifying the Coleman methodology score (CMS).

STUDY DESIGN

Systematic review.

METHODS

For this review, a literature search was performed to identify all published and unpublished clinical studies of matrix-assisted (second-generation) autologous chondrocyte transplantation using the following medical electronic databases: MEDLINE, MEDLINE preprints, EMBASE, CINAHL, Life Science Citations, and British National Library of Health, including the Cochrane Central Register of Controlled Trials (CENTRAL). The search period was January 1, 1995, to July 1, 2008. To better assess cartilage-related studies, a modification of the CMS was proposed.

RESULTS

Eighteen studies were included in the analysis, reporting on 731 patients with an average follow-up of 27.3 months (6.5-60.0 months). Of the 18 studies, 2 were randomized controlled studies, 3 were prospective comparative studies, 11 were prospective cohort studies or prospective case series, and 2 were retrospective case series. Original CMSs for these studies (55.1 +/- 1.6) were significantly higher than those of cartilage repair studies in general (43.5 +/- 1.6, P < .0001) reported in 2005. The statistical analysis indicated that the modified CMS showed higher correlations and lower variability of correlations among 3 reviewers.

CONCLUSION

The quality of the currently available data on second-generation autologous chondrocyte transplantation is still limited by study designs. The modified CMS has demonstrated better sensitivity and reproducibility with respect to the original score, so it can be recommended for cartilage clinical studies evaluation.

Treatment of osteochondritis dissecans of the femoral condyle with autologous bone grafts and matrix-supported autologous chondrocytes

The objective of this study was to determine the clinical outcome of combined bone grafting and matrix-supported autologous chondrocyte transplantation in patients with osteochondritis dissecans of the knee. Between January 2003 and March 2005, 21 patients (mean age 29.33 years) with symptomatic osteochondritis dissecans (OCD) of the medial or lateral condyle (grade III or IV) of the knee underwent reconstruction of the joint surface by autologous bone grafts and matrix-supported autologous chondrocyte transplantation. Patients were followed up at three, six, 12 and 36 months to determine outcomes by clinical evaluation based on Lysholm score, IKDC and ICRS score. Clinical results showed a significant improvement of Lysholm-score and IKDC score. With respect to clinical assessment, 18 of 21 patients showed good or excellent results 36 months postoperatively. Our study suggests that treatment of OCD with autologous bone grafts and matrix-supported autologous chondrocytes is a possible alternative to osteochondral cylinder transfer or conventional ACT.

Osteochondral autologous transplantation for the treatment of full-thickness cartilage defects of the shoulder

We describe the outcome at a mean follow-up of 8.75 years (7.6 to 9.8) of seven patients who had undergone osteochondral autologous transplantation for full-thickness cartilage defects of the shoulder between 1998 and 2000. These patients have been described previously at a mean of 32.6 months when eight were included. One patient has been lost to follow-up. The outcome was assessed by the Constant shoulder score and the Lysholm knee score to assess any donor-site morbidity. Standard radiographs and MR scores were obtained and compared with the pre-operative findings and the results from the previous review.

No patient required any further surgery on the shoulder. The mean Constant score improved significantly until the final follow-up (p = 0.018). The Lysholm score remained excellent throughout. There was a significant progression of osteoarthritic changes from the initial surgery to the first and final follow-up but this did not appear to be related to the size of the defect, the number of cylinders required or the Constant score (p = 0.016). MRI showed that all except one patient had a congruent joint surface at the defect with full bony integration of all osteochondral cylinders.

The results have remained satisfactory over a longer period with very good objective and subjective findings.