Outcomes After a Single-Stage Procedure for Cell-Based Cartilage Repair Autologous chondrocyte implantation for knee cartilage injuries: moderate functional outcome and performance in patients with high-impact activities. Articular cartilage defects in 1,000 knee arthroscopies. NeoCart, an autologous cartilage tissue implant, compared with microfracture for treatment of distal femoral cartilage lesions: an FDA phase-II prospective, randomized clinical trial after two years. Autologous chondrocyte implantation for cartilage repair: monitoring its success by magnetic resonance imaging and histology The role of autologous chondrocyte implantation in the treatment of symptomatic chondromalacia patellae Autologous Chondrocyte Implantation and Osteochondral Cylinder Transplantation in Cartilage Repair of the Knee Joint: A Prospective, Comparative Trial A prospective, randomised study comparing two techniques of autologous chondrocyte implantation for osteochondral defects in the knee: Periosteum covered versus type I/III collagen covered. Knee Cartilage Defect Patients Enrolled in Randomized Controlled Trials Are Not Representative of Patients in Orthopedic Practice Autologous chondrocyte implantation: a comparison between an open periosteal-covered and an arthroscopic matrix-guided technique. Autologous chondrocyte implantation versus matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee: a prospective, randomised study. A prospective, randomised comparison of autologous chondrocyte implantation versus mosaicplasty for osteochondral defects in the knee. Cell Therapy in Joint Disorders Autologous chondrocyte implantation versus microfracture for knee cartilage injury: a prospective randomized trial, with 2-year follow-up Comparison of two different matrix-based autologous chondrocyte transplantation systems: 1 year follow-up results Arthroscopic Second-Generation Autologous Chondrocyte Implantation Compared with Microfracture for Chondral Lesions of the Knee Matrix-induced autologous chondrocyte implantation versus microfracture in the treatment of cartilage defects of the knee: a 2-year randomised study Five-Year Outcome of Characterized Chondrocyte Implantation Versus Microfracture for Symptomatic Cartilage Defects of the Knee Matrix-Applied Characterized Autologous Cultured Chondrocytes Versus Microfracture Treatment of Symptomatic Cartilage Defects of the Knee A randomized trial comparing autologous chondrocyte implantation with microfracture. Findings at five years. Comparative Evaluation of Autologous Chondrocyte Implantation and Mosaicplasty: A Multicentered Randomized Clinical Trial [Osteochondral transplantation versus autogenous chondrocyte transplantation. A prospective comparative clinical study]. Minimum ten-year results of a prospective randomised study of autologous chondrocyte implantation versus mosaicplasty for symptomatic articular cartilage lesions of the knee. Current Treatments of Isolated Articular Cartilage Lesions of the Knee Achieve Similar Outcomes Autologous chondrocyte implantation compared with microfracture in the knee. A randomized trial. Characterized Chondrocyte Implantation Results in Better Structural Repair When Treating Symptomatic Cartilage Defects of the Knee in a Randomized Controlled Trial versus Microfracture Second-Generation Autologous Chondrocyte Implantation
Background : There are currently several approaches being pursued to treat focal defects of articular cartilage , each having specific advantages or challenges . A single-stage procedure that uses autologous cartilage fragments , Cartilage Autograft Implantation System ( CAIS ) , is being evaluated in patients and may offer a clinical ly effective option . Purpose : To establish the safety of CAIS and to test whether CAIS improves quality of life by using st and ardized outcomes assessment tools . Study Design : R and omized controlled trial ; Level of evidence , 2 . Methods : Patients ( n = 29 ) were r and omized ( 1:2 ) with the intent to treat with either a  control ( microfracture [ MFX ] ) or an experimental ( CAIS ) procedure . Patients were followed at predetermined time points for 2 years using several st and ardized outcomes assessment tools ( SF-36 , International Knee Documentation Committee [ IKDC ] , Knee injury and Osteoarthritis Outcome Score [ KOOS ] ) . Magnetic resonance imaging was performed at baseline , 3 weeks , and 6 , 12 , and 24 months . Results : Lesion size and International Cartilage Repair Society ( ICRS ) grade were similar in both groups . General outcome measures ( eg , physical component score of the SF-36 ) indicated an overall improvement in both groups , and no differences in the number of adverse effects were noted in comparisons between the CAIS and MFX groups . The IKDC score of the CAIS group was significantly higher ( 73.9 ± 14.72 at 12 months and 82.95 ± 14.88 at 24 months ) compared with the MFX group ( 57.78 ± 18.31 at 12 months and 59.5 ± 13.44 at 24 months ) . Select subdomains ( 4/5 ) in the KOOS instrument were significantly different at 12 and 18 months , and all subdomains ( Symptoms and Stiffness , Pain , Activities of Daily Living , Sports and Recreation , Knee-related Quality of Life ) were significantly increased at 24 months in CAIS with scores of 88.47 ± 11.68 , 90.64 ± 7.87 , 97.29 ± 3.8 , 78.16 ± 22.06 , and 69 ± 23.15 compared with 75 ± 9.31 , 78.94 ± 13.73 , 89.46 ± 8.13 , 51.67 ± 26.01 , and 37.15 ± 21.67 in the MFX group . These significant improvements were maintained at 24 months in both IKDC and KOOS . Qualitative analysis of the imaging data did not note differences between the 2 groups in fill of the graft bed , tissue integration , or presence of subchondral cysts . Patients treated with MFX had a significantly higher incidence of intralesional osteophyte formation ( 54 % and 70 % of total number of lesions treated ) at 6 and 12 months when compared with CAIS ( 8 % and 25 % of total number of lesions treated ) . Conclusion : The first clinical experience in using CAIS for treating patients with focal chondral defects indicates that it is a safe , feasible , and effective method that may improve long-term clinical outcomes 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 r and omization . 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 PURPOSE Focal chondral or osteochondral defects can be painful and disabling , have a poor capacity for repair , and may predispose patients for osteoarthritis . New surgical procedures that aim to reestablish hyaline cartilage have been introduced and the results seem promising . The purpose of this study is to provide reliable data on chondral and osteochondral defects in patients with symptomatic knees requiring arthroscopy  and to calculate the prevalence of patients who might benefit from cartilage repair surgery . TYPE OF STUDY Prospect i ve study . METHODS One thous and consecutive knee arthroscopies were included in this study . Immediately after each arthroscopy , the surgeon completed a question naire providing detailed information about the findings . Chondral and osteochondral lesions were classified in accordance with the system recommended by the International Cartilage Repair Society ( ICRS ) . RESULTS Chondral or osteochondral lesions ( of any type ) were found in 61 % of the patients . Focal chondral or osteochondral defects were found in 19 % of the patients . In these patients , 61 % related their current knee problem to a previous trauma , and a concomitant meniscal or anterior cruciate ligament injury was found in 42 % ( n = 81 ) and 26 % ( n = 50 ) , respectively . The mean chondral or osteochondral total defect area was 2.1 cm(2 ) ( range , 0.5 to 12 ; st and ard deviation [ SD ] , 1.5 ) . The main focal chondral or osteochondral defect was found on the medial femoral condyle in 58 % , patella in 11 % , lateral tibia in 11 % , lateral femoral condyle in 9 % , trochlea in 6 % , and medial tibia in 5 % . It has been suggested that cartilage repair surgery may be most suitable in patients younger than 40 to 50 years old . A single , well-defined ICRS grade III or IV defect with an area of at least 1 cm(2 ) in a patient younger than 40 , 45 , or 50 years accounted for 5.3 % , 6.1 % , and 7.1 % of all arthroscopies , respectively . CONCLUSIONS Our study supports the contention that articular cartilage defects are common . It has the advantages of a prospect i ve design and use of a new classification system recommended by the ICRS . This modern system focuses on objective ly measurable parameters of the lesion 's extent and not its surface appearance BACKGROUND Despite introduction of autologous chondrocyte therapy for repair of hyaline articular cartilage injury in 1994 , microfracture remains a primary st and ard of care . NeoCart , an autologous cartilage tissue implant , was compared with microfracture in a multisite prospect i ve , r and omized trial of a tissue-engineered bioimplant for treating articular cartilage injuries in the knee . METHODS Thirty patients were r and omized at a ratio of two to one ( two were treated with an autologous cartilage tissue implant [ NeoCart ] for each patient treated with microfracture )  at the time of arthroscopic confirmation of an International Cartilage Repair Society ( ICRS ) grade -III lesion(s ) . Microfracture or cartilage biopsy was performed . NeoCart , produced by seeding a type-I collagen matrix scaffold with autogenous chondrocytes and bioreactor treatment , was implanted six weeks following arthroscopic cartilage biopsy . St and ard evaluations were performed with vali date d clinical outcomes measures . RESULTS Three , six , twelve , and twenty-four-month data are reported . The mean duration of follow-up ( and st and ard deviation ) was 26 ± 2 months . There were twenty-one patients in the NeoCart group and nine in the microfracture group . The mean age ( 40 ± 9 years ) , body mass index ( BMI ) ( 28 ± 4 kg/m2 ) , duration between the first symptoms and treatment ( 3 ± 5 years ) , and lesion size ( 287 ± 138 mm2 in the NeoCart group and 252 ± 135 mm2 in the microfracture group ) were similar between the groups . Adverse event rates per procedure did not differ between the treatment arms . The scores on the Short Form-36 ( SF-36 ) , Knee Injury and Osteoarthritis Outcome Score ( KOOS ) activities of daily living ( ADL ) scale , and International Knee Documentation Committee ( IKDC ) form improved from baseline ( p < 0.05 ) to two years postoperatively in both treatment groups . In the NeoCart group , improvement , compared with baseline , was significant ( p < 0.05 ) for all measures at six , twelve , and twenty-four months . Improvement in the NeoCart group was significantly greater ( p < 0.05 ) than that in the microfracture group for the KOOS pain score at six , twelve , and twenty-four months ; the KOOS symptom score at six months ; the IKDC , KOOS sports , and visual analog scale ( VAS ) pain scores at twelve and twenty-four months ; and the KOOS quality of life ( QOL ) score at twenty-four months . Analysis of covariance ( ANCOVA ) at one year indicated that the change in the KOOS pain ( p = 0.016 ) and IKDC ( p = 0.028 ) scores from pretreatment levels favored the NeoCart group . Significantly more NeoCart-treated patients ( p = 0.0125 ) had responded to therapy ( were therapeutic responders ) at six months ( 43 % versus 25 % in the microfracture group ) and twelve months ( 76 % versus 22 % in the microfracture group ) . This trend continued , as the proportion of NeoCart-treated patients ( fifteen of nineteen ) who were therapeutic responders at twenty-four months was greater than the proportion of microfracture-treated participants ( four of nine ) who were therapeutic responders at that time . CONCLUSIONS This r and omized study suggests that the safety of autologous cartilage tissue implantation , with use of the NeoCart technique , is similar to that of microfracture surgery and is associated with greater clinical efficacy at two years after treatment Autologous chondrocyte implantation is being used increasingly for the treatment of cartilage defects . In spite of this , there has been a paucity of objective , st and ardised assessment of the outcome and quality of repair tissue formed . We have investigated patients treated with autologous chondrocyte implantation ( ACI ) , some in conjunction with mosaicplasty  , and developed objective , semiquantitative scoring schemes to monitor the repair tissue using MRI and histology . Results indicate repair tissue to be on average 2.5 mm thick . It was of varying morphology ranging from predominantly hyaline in 22 % of biopsy specimens , mixed in 48 % , through to predominantly fibrocartilage , in 30 % , apparently improving with increasing time postgraft . Repair tissue was well integrated with the host tissue in all aspects viewed . MRI scans provide a useful assessment of properties of the whole graft area and adjacent tissue and is a noninvasive technique for long-term follow-up . It correlated with histology ( P = 0.02 ) in patients treated with ACI alone Purpose Chondromalacia patella is a distinct clinical entity of abnormal softening of the articular cartilage of the patella , which results in chronic retropatellar pain . Its aetiology is still unclear but the process is thought to be a due to trauma to superficial chondrocytes result ing in a proteolytic enzymic breakdown of the matrix . Our aim was to assess the effectiveness of autologous chondrocyte implantation on patients with a proven symptomatic retropatellar lesion who had at least one failed conventional marrow-stimulating therapy . Methods We performed chondrocyte implantation on 48 patients : 25 received  autologous chondrocyte implantation with a type I/III membrane ( ACI-C ) method ( Geistlich Bio material s , Wolhusen , Switzerl and ) , and 23 received the Matrix-assisted Chondrocyte Implantation ( MACI ) technique ( Genzyme , Kastrup , Denmark ) . Results Over a mean follow-up period of 40.3 months , there was a statistically significant improvement in subjective pain scoring using the visual analogue scale ( VAS ) and objective functional scores using the Modified Cincinnati Rating System ( MCS ) in both groups . Conclusions Chondromalacia patellae lesions responded well to chondrocyte implantation . Better results occurred with MACI than with ACI-C. Excellent and good results were achieved in 40 % of ACI-C patients and 57 % of MACI patients , but success of chondrocyte implantation was greater with medial/odd-facet lesions . Given that the MACI procedure is technically easier and less time consuming , we consider it to be useful for treating patients with symptomatic chondral defects secondary to chondromalacia patellae Background : Current methods used to restore the joint surface in patients with localized articular cartilage defects include transplantation of an autologous osteochondral cylinder and implantation of autologous chondrocytes . The purpose of this study was to evaluate the clinical and histological outcomes of these two techniques . Methods : We performed a prospect i ve clinical study to investigate the two-year outcomes in forty patients with an articular cartilage lesion of the femoral condyle who had been r and omly treated with either transplantation of an autologous osteochondral cylinder or implantation of autologous chondrocytes . Biopsy specimens from representative patients of both groups were evaluated with histological staining , immunohistochemistry , and scanning electron microscopy . Results : According to the postoperative Lysholm score , the recovery after autologous chondrocyte implantation was slower than that after osteochondral transplantation at six months ( p ⩽ 0.015 ) , twelve months ( p ⩽ 0.001 ) , and twenty-four months ( p ⩽ 0.012 ) . On the basis of the Meyers score and the Tegner activity score , the results were equally good with the two methods two years after treatment . Histomorphological evaluation of biopsy specimens within two years after autologous chondrocyte implantation demonstrated a complete , mechanically stable resurfacing of the defect in all patients . The tissue consisted mainly of fibrocartilage , while localized areas of hyaline-like regenerative cartilage could be detected close to the subchondral bone . Although a gap remained at the site of the transplantation in all five biopsy specimens examined as long as two years after osteochondral cylinder transplantation , histomorphological analysis and scanning electron microscopy revealed no differences between the osteochondral transplants and the surrounding original cartilage . Conclusions : Both treatments result ed in a decrease in symptoms . However , the improvement provided by the autologous chondrocyte implantation lagged behind that provided by the osteochondral cylinder transplantation . Histologically , the defects treated with autologous chondrocyte implantation were primarily filled with fibrocartilage , whereas the osteochondral cylinder transplants retained their hyaline character , although there was a persistent interface between the transplant and the surrounding original cartilage . Limitations of our study included the small number of patients , the relatively short ( two-year ) follow-up , and the absence of a control group . Level of Evidence : Therapeutic study , Level II-2 ( poor- quality r and omized controlled trial [ e.g. , < 80 % follow-up ] ) . See Instructions to Authors for a complete description of levels of evidence INTRODUCTION The results for autologous chondrocyte implantation ( ACI ) in the treatment of full thickness chondral defects in the knee are encouraging . At present two techniques have been described to retain the chondrocyte suspension within the defect . The first involves using a periosteal cover ( ACI-P ) and the second involves using a type I/III collagen membrane ( ACI-C ) . To the authors knowledge there are no comparative studies of these two techniques in the current literature . We have therefore undertaken such a study to establish if there is a difference between the 2 techniques based on a clinical and arthroscopic assessment . METHODS A total of 68 patients with a mean age of 30.52 years with symptomatic articular cartilage defects were r and omised to have either ACI-P ( 33 patients ) or ACI-C ( 35 patients ) . The mean defect size was 4.54 cm2 . All patients were followed up at 24 months . RESULTS A clinical and functional assessment showed that 74 % of patients had a good or excellent result following the ACI-C compared with 67 % after the ACI-P at 2 years . Arthroscopy at 1 year also demonstrated similar results for both techniques . However , 36.4 % of the ACI-P grafts required shaving for hypertrophy compared with none for the ACI-C grafts at 1 year . DISCUSSION This study has shown no statistical difference between the clinical outcome of ACI-C versus ACI-P at 2 years . A significant number of patients who had the ACI-P required shaving of a hypertrophied graft . We conclude that there is no advantage in using periosteum as a cover for retaining chondrocytes within an osteochondral defect ; as a result we advocate the use of an alternative cover such as a manufactured type I/III collagen membrane Objective : Knee cartilage defects represent a socioeconomic burden and may cause lifelong disability . Studies have shown that cartilage defects are detected in approximately 60 % of knee arthroscopies . In clinical trials , the majority of these patients are excluded . This study investigates whether patients included in r and omized controlled trials ( RCTs )  represent a selected group compared to general cartilage patients . Design : Published r and omized clinical trials on cartilage repair studies were identified ( May 2009 ) and analyzed to define common inclusion criteria that in turn were applied to all patients su bmi tted to our cartilage repair center during 2008 .  Patient-administered Lysholm knee score was used to evaluate functional level at referral . In addition , previous surgery and size and localization of cartilage defects were recorded . Results : Common inclusion criteria in the referred patients and patients included in the published RCTs were single femoral condyle lesion , age range 18 to 40 years , and size of lesion range 3.2 to 4.0 cm2 . Six of 137 referred patients matched all the 7 RCTs . Previous cartilage repair and multiple lesions were associated with decreased Lysholm score ( P < 0.002 ) . Lysholm score was independent of age , gender , and time of symptoms from the defect . Conclusion : The heterogeneity of the referred cartilage patients and the variation in inclusion criteria in the RCTs may question whether RCTs actually represent the general cartilage patients . The present study suggests that results from published RCTs may not be representative of the gross cartilage population In this prospect i ve study , the authors compared the Carticel method of autologous chondrocyte implantation with the Hyalograft C technique . The aim of the study was to compare the clinical outcomes of the two methods , to identify any complications and to analyse MRI images of the repair process . Seventeen patients who had received autologous chondrocyte implantation with the Carticel technique and ten treated with Hyalograft C were assessed . A statistically significant improvement was observed in both groups at six months ( p < 0.001 for Carticel and p = 0.002 for Hyalograft C ) and at twelve months after surgery ( p < 0.001 both for Carticel and Hyalograft C ) , according to HSS ( Hospital for Special Surgery ) and ICRS ( International Cartilage Repair Society ) scores . There were no statistically significant differences between the two groups . MRI images obtained one year after surgery revealed the formation of well-integrated tissue similar to the surrounding healthy cartilage in most cases , in both Carticel and Hyalograft C groups . Six patients treated with Carticel technique  were also assessed by second-look arthroscopy and histology of biopsies . The newly-formed tissue presented structural features similar to normal cartilage in most cases ( 84 % ) . Molecular analysis was performed to assess mRNA levels of the various collagen molecules and proliferation and differentiation factors : the results showed that the implanted material undergoes progressive remodelling to regenerate hyaline cartilage . Both Carticel and Hyalograft C implantation techniques seem to lead to comparable short- and medium-term results . Moreover , this study confirmed that MRI is a valid tool in the follow-up evaluation of autologous chondrocyte implantation Autologous chondrocyte implantation ( ACI ) is used widely as a treatment for  symptomatic chondral and osteochondral defects of the knee . Variations of the original periosteum-cover technique include the use of porcine-derived type I/type III collagen as a cover ( ACI-C ) and matrix-induced autologous chondrocyte implantation ( MACI ) using a collagen bilayer seeded with chondrocytes . We have performed a prospect i ve , r and omised comparison of ACI-C and MACI for the treatment of symptomatic chondral defects of the knee in 91 patients , of whom 44 received ACI-C and 47 MACI grafts .  Both treatments result ed in improvement of the clinical score after one year . The mean modified Cincinnati knee score increased by 17.6 in the ACI-C group and 19.6 in the MACI group ( p = 0.32 ) . Arthroscopic assessment s performed after one year showed a good to excellent International Cartilage Repair Society score in 79.2 % of ACI-C and 66.6 % of MACI grafts . Hyaline-like cartilage or hyaline-like cartilage with fibrocartilage was found in the biopsies of 43.9 % of the ACI-C and 36.4 % of the MACI grafts after one year . The rate of hypertrophy of the graft was 9 % ( 4 of 44 ) in the ACI-C group and 6 % ( 3 of 47 ) in the MACI group . The frequency of re-operation was 9 % in each group . We conclude that the clinical , arthroscopic and histological outcomes are comparable for both ACI-C and MACI . While MACI is technically attractive , further long-term studies are required before the technique is widely adopted Autologous chondrocyte implantation ( ACI ) and mosaicplasty are both cl aim ed to be successful for the repair of defects of the articular cartilage of the knee but there has been no comparative study of the two methods . A total of 100 patients with a mean age of 31.3 years ( 16 to 49 ) and with a symptomatic lesion of the articular cartilage in the knee which was suitable for cartilage repair was r and omised to undergo either  ACI or mosaicplasty ; 58 patients had ACI and 42 mosaicplasty .  Most lesions were post-traumatic and the mean size of the defect was 4.66 cm2 . The mean duration of symptoms was 7.2 years and the mean number of previous operations , excluding arthroscopy , was 1.5 . The mean follow-up was 19 months ( 12 to 26 ) . Functional assessment using the modified Cincinatti and Stanmore scores and objective clinical assessment showed that 88 % had excellent or good results after ACI compared with 69 % after mosaicplasty . Arthroscopy at one year demonstrated excellent or good repairs in 82 % after ACI and in 34 % after mosaicplasty . All five patellar mosaicplasties failed . Our prospect i ve , r and omised , clinical trial has shown significant superiority of ACI over mosaicplasty for the repair of articular defects in the knee . The results for ACI are comparable with those in other studies , but those for mosaicplasty suggest that its continued use is of dubious value Context : Articular cartilage possesses poor natural healing mechanisms , and a variety of non-cell-based and cell-based treatments aim to promote regeneration of hyaline cartilage . Data Sources : A review of the literature to December 2013 using PubMed with search criteria including the keywords stem cell , cell therapy , cell transplantation , cartilage , chondral , and chondrogenic . Study Selection : Forty-five articles were identified that employed local mesenchymal stem cell ( MSC ) therapy for joint disorders in humans . Nine comparative studies were identified , consisting of 3 r and omized trials , 5 cohort studies , and 1 case-control study . Study Type : Clinical review . Level of Evidence : Level 4 . Data Extraction : Studies were assessed for stem cell source , method of implantation , comparison groups , and concurrent surgical techniques . Results : Two studies comparing MSC treatment to autologous chondrocyte implantation found similar efficacy . Three studies reported clinical benefits with intra-articular MSC injection over non-MSC controls for cases undergoing debridement with or without marrow stimulation , although a r and omized study found no significant clinical difference at 2-year follow-up but reported better 18-month magnetic resonance imaging and histologic scores in the MSC group . No human studies have compared intra-articular MSC therapy to non-MSC techniques for osteoarthritis in the absence of surgery . Conclusion : Mesenchymal stem cell – based therapies appear safe and effective for joint disorders in large animal pre clinical models . Evidence for use in humans , particularly , comparison with more established treatments such as autologous chondrocyte implantation and microfracture , is limited The objective was to evaluate the functional performance over a 2-year period following autologous chondrocyte implantation ( ACI ) in an open knee procedure compared to microfracture . Objective functional outcome was studied as secondary analysis in a subgroup of patients , in a r and omized clinical trial , with concealed allocation and independent evaluators . Sixty-seven patients with local cartilage defect , with a mean size of 2.4 cm² ( SD 1.5 ) of the femoral condyle of the knee were included . Thirty-three patients underwent the microfracture and 34 the ACI procedure .  An identical rehabilitation protocol was implemented for both groups . Active knee flexion and extension range , anterior laxity , knee extension strength ( concentric at 60 ° /s ) and single leg hop performance ( single hop , crossover triple hop and 6 m timed hop test ) were evaluated pre-surgery and at 6 , 9,12 and 24 months post-surgery . We calculated the symmetry index for individual and four performance tests pooled . Mixed linear model analyses were used with confidence interval set at 95 % . The change over 2 years for the pooled performance-based tests was comparable between the two treatment arms . At 2 years , 70 % ( 38/54 ) of all patients returned to > 85 % symmetry in overall functional performance . A decrease in functional performance at 6 months following ACI result ed in slower recovery at 9 and 12 months compared to microfracture . Rehabilitation following both cartilage repair procedures is a lengthy process . At 2 years after surgery , ACI patients have similar overall functional outcome compared to microfracture patients Purpose The treatment of full-thickness cartilage defects of the knee is a common problem in orthopaedic surgery . Autologous chondrocyte transplantation ( ACT ) is one of the few reliable treatment options of cartilage defects with good long-term outcomes . The improvement of ACT led to the matrix-based ACT ( MACT ) . The purpose of the study was to compare two different commercially available MACT systems . Methods Eleven patients with a cartilage defect of the knee were treated with the MACI ® system and another nine patients with the CaRes ® implant .  The patients were prospect ively followed and re-examined after one year . Results One year after surgery all but one patient have significantly improved in their clinical outcome . Both types of MACT revealed similar results in terms of increase in level of activity , pain relief and knee function . Conclusion The study showed that MACT is a good therapeutic option for full-size defects of the femoral condyle . The MACI ® implant seems to be easier to h and le which is reflected by smaller incisions and a shorter operation time Background Various approaches have been proposed to treat articular cartilage lesions , which are plagued by inherent limited healing potential . Purpose To compare the clinical outcome of patients treated with second-generation autologous chondrocyte implantation implants with those treated with the microfracture repair technique at 5-year follow-up . Study Design Cohort study ; Level of evidence , 2 . Methods Eighty active patients ( mean age , 29.8 years ) and grade III to IV cartilage lesions of the femoral condyles or trochlea were treated with  arthroscopic second-generation autologous chondrocyte implantation Hyalograft C or microfracture ( 40 patients per group ) . Patients achieved a minimum 5-year follow-up and were prospect ively evaluated . Results Both groups showed statistically significant improvement of all clinical scores from preoperative interval to 5-year follow-up . There was a significant improvement for the International Knee Documentation Committee subjective score from preoperative to 5-year follow-up ( Wilcoxon test , P < .001 ) . In the microfracture group , the International Knee Documentation Committee objective score increased from 2.5 % normal and nearly normal knees before the operation to 75 % normal and nearly normal knees at 5-year follow-up , and the subjective score increased from 41.1 ± 12.3 preoperatively to 70.2 ± 14.7 at 5-year follow-up . In the group treated with Hyalograft C , the International Knee Documentation Committee objective score increased from 15 % normal and nearly normal knees before the operation to 90 % normal and nearly normal knees at 5-year follow-up , and its subjective score increased from 40.5 ± 15.2 preoperatively to 80.2 ± 19.1 at 5-year follow-up ( Wilcoxon test , P < .001 ) . When comparing the groups , better improvement of the International Knee Documentation Committee objective ( P < .001 ) and subjective ( P = .003 ) scores was observed in the Hyalograft C group at 5-year follow-up . The return to sports at 2 years was similar in both groups and remained stable after 5 years in the Hyalograft C group ; it worsened in the microfracture group . Conclusion Both methods have shown satisfactory clinical outcome at medium-term follow-up . Better clinical results and sport activity resumption were noted in the group treated with second-generation autologous chondrocyte transplantation Cartilage defects occur in approximately 12 % of the population and can result in significant function impairment and reduction in quality of life . Evidence for the variety of surgical treatments available is inconclusive . This study aim ed to compare the clinical outcomes of patients with symptomatic cartilage defects treated with matrix-induced autologous chondrocyte implantation ( MACI ™ or microfracture ( MF ) . Included patients were ≥18 and ≤50 years of age with symptomatic , post-traumatic , single , isolated chondral defects ( 4–10 cm2 ) and were r and omised to receive MACI ™ or MF .  Patients were followed up 8–12 , 22–26 and 50–54 weeks post-operatively for efficacy and safety evaluation . Outcome measures were the Tegner , Lysholm and ICRS scores . Sixty patients were included in a r and omised study ( 40 MACI ™ , 20 MF ) . The difference between baseline and 24 months post-operatively for both treatment groups was significant for the Lysholm , Tegner , patient ICRS and surgeon ICRS scores ( all P < 0.0001 ) . However , MACI ™ was significantly more effective over time ( 24 months versus baseline ) than MF according to the Lysholm ( P = 0.005 ) , Tegner ( P = 0.04 ) , ICRS patient ( P = 0.03 ) and ICRS surgeon ( P = 0.02 ) scores . There were no safety issues related to MACI ™ or MF during the study . MACI ™ is superior to MF in the treatment of articular defects over 2 years . MACI ™ and MF are complementary procedures , depending on the size of the defect and symptom recurrence . The MACI ™ technique represents a significant advance over both first and second generation chondrocyte-based cartilage repair techniques for surgeons , patients , health care institutions and payers in terms of reproducibility , safety , intraoperative time , surgical simplicity and reduced invasiveness Background : Characterized chondrocyte implantation ( CCI ) results in significantly better early structural tissue regeneration than microfracture ( MF ) , and CCI has a midterm clinical benefit over microfracture . Purpose : This study was undertaken to evaluate the 5-year clinical outcome of CCI in a r and omized comparison with MF for the treatment of symptomatic cartilage defects of the femoral condyles of the knee . Study Design : R and omized controlled trial ; Level of evidence , 1 . Methods : Participants aged 18 to 50 years with a symptomatic isolated International Cartilage Repair Society ( ICRS ) grade III or IV cartilage lesion of the femoral condyles between 1 and 5 cm2 were r and omized to either  CCI or MF .  Clinical outcomes were measured up to 60 months after surgery using the Knee Injury and Osteoarthritis Outcome Score ( KOOS ) . The main outcome parameter was change from baseline in overall KOOS ( oKOOS ) . Adverse events were monitored . Results : Fifty-one participants were treated with CCI and 61 with MF . On average , clinical benefit was maintained through the 60-month follow-up period . The average change from baseline in oKOOS was not different between both groups ( least squares [ LS ] mean ± st and ard error [ SE ] 18.84 ± 3.58 for CCI vs 13.21 ± 5.63 for MF ; P = .116 ) . Treatment failures were comparable ( n = 7 in CCI vs n = 10 in MF ) , although MF failures tended to occur earlier . Subgroup analysis revealed that CCI result ed in better outcome in participants with time since symptom onset of less than 3 years , which was statistically significant and clinical ly relevant ( change in oKOOS <3 years mean ± SE 25.96 ± 3.45 for CCI vs 15.28 ± 3.17 for MF ; P = .026 vs oKOOS > 3 years mean ± SE 13.09 ± 4.78 for CCI vs 17.02 ± 4.50 for MF , P = .554 ) . Other subgroup analyses such as age ( cutoff 35 years ) did not show a difference . Female patients showed more failures irrespective of treatment . Conclusion : At 5 years after treatment , clinical outcomes for CCI and MF were comparable . In the early treatment group , CCI obtained statistically significant and clinical ly relevant better results than MF . Delayed treatment result ed in less predictable outcomes for CCI . These results provide strong evidence that time since onset of symptoms is an essential variable that should be taken into account in future treatment algorithms for  cartilage repair  of the knee Background : R and omized controlled trials study ing the efficacy and safety of matrix-applied characterized autologous cultured chondrocytes ( MACI ) versus microfracture ( MFX ) for treating cartilage defects are limited . Purpose : To compare the clinical efficacy and safety of MACI versus MFX in the treatment of patients with symptomatic cartilage defects of the knee . Study Design : R and omized controlled clinical trial ; Level of evidence , 1 . Methods : Patients enrolled in the SUMMIT ( Demonstrate the Superiority of MACI implant to Microfracture Treatment )  trial had ≥1 symptomatic focal cartilage defect ( Outerbridge grade III or IV ; ≥3 cm2 ) of the femoral condyles or trochlea , with a baseline Knee Injury and Osteoarthritis Outcome Score ( KOOS ) pain value < 55 . The co– primary efficacy endpoint was the change in the KOOS pain and function subscores from baseline to 2 years . Histological evaluation and magnetic resonance imaging ( MRI ) assessment s of structural repair tissue , treatment failure , the remaining 3 KOOS subscales , and safety were also assessed . Results : Of the 144 patients treated , 137 ( 95 % ) completed the 2-year assessment . Patients had a mean age of 33.8 years and a mean lesion size of 4.8 cm2 .  The mean KOOS pain and function subscores from baseline to 2 years were significantly more improved with MACI than with MFX ( pain : MACI , 37.0 to 82.5 vs MFX , 35.5 to 70.9 ; function : MACI , 14.9 to 60.9 vs MFX , 12.6 to 48.7 ; P = .001 ) . A significant improvement in scores was also observed on the KOOS subscales of activities of daily living ( MACI , 43.5 to 87.2 vs MFX , 42.6 to 75.8 ; P < .001 ) , knee-related quality of life ( MACI , 18.8 to 56.2 vs MFX , 17.2 to 47.3 ; P = .029 ) , and other symptoms ( MACI , 48.3 to 83.7 vs MFX , 44.4 to 72.2 ; P < .001 ) for patients treated with MACI compared with MFX . Repair tissue quality was good as assessed by histology/MRI , but no difference was shown between treatments . A low number of treatment failures ( nonresponders : MACI , 12.5 % vs MFX , 31.9 % ; P = .016 ) and no unexpected safety findings were reported . Conclusion : The treatment of symptomatic cartilage knee defects ≥3 cm2 in size using MACI was clinical ly and statistically significantly better than with MFX , with similar structural repair tissue and safety , in this heterogeneous patient population . Moreover , MACI offers a more efficacious alternative than MFX with a similar safety profile for the treatment of symptomatic articular cartilage defects of the knee Background Damaged articular cartilage has limited capacity for self-repair . Autologous chondrocyte implantation using a characterized cell therapy product results in significantly better early structural repair as compared with microfracture in patients with symptomatic joint surface defects of the femoral condyles of the knee . Purpose To evaluate clinical outcome at 36 months after characterized chondrocyte implantation ( CCI ) versus microfracture ( MF ) . Study Design R and omized controlled trial ; Level of evidence , 1 . Methods Patients aged 18 to 50 years with single International Cartilage Repair Society ( ICRS ) grade III/IV symptomatic cartilage defects of the femoral condyles were r and omized to CCI ( n = 57 ) or MF ( n = 61 ) . Clinical outcome was measured over 36 months by the Knee injury and Osteoarthritis Outcome Score ( KOOS ) . Serial magnetic resonance imaging ( MRI ) scans were scored using the Magnetic resonance Observation of Cartilage Repair Tissue ( MOCART ) system and 9 additional items . Gene expression profile scores associated with ectopic cartilage formation were determined by RT-PCR . Results Baseline mean overall KOOS ( ±SE ) was comparable between the CCI and MF groups ( 56.30 ± 1.91 vs 59.46 ± 1.98 , respectively ) . Mean improvement ( ±SE ) from baseline to 36 months in overall KOOS was greater in the CCI group than the MF group ( 21.25 ± 3.60 vs 15.83 ± 3.48 , respectively ) , while in a mixed linear model analysis with time as a categorical variable , significant differences favoring CCI were shown in overall KOOS ( P = .048 ) and the subdomains of Pain ( P = .044 ) and QoL ( P = .036 ) . More CCI- than MF-treated patients were treatment responders ( 83 % vs 62 % , respectively ) . In patients with symptom onset of < 2 years , the mean improvement ( ±SE ) from baseline to 36 months in overall KOOS was greater with CCI than MF ( 24.98 ± 4.34 vs 16.50 ± 3.99 , respectively ) and even greater in patients with symptom onset of <3 years ( 26.08 ± 4.10 vs 17.09 ± 3.77 , respectively ) . Characterized chondrocyte implantation patients with high ( > 2 ) versus low ( < 2 ) gene profile scores showed greater improvement from baseline in mean overall KOOS ( ±SE ) at 36 months ( 28.91 ± 5.69 vs 18.18 ± 5.08 , respectively ) . Subchondral bone reaction significantly worsened over time with MF compared with CCI ( P < .05 ) . Conclusion Characterized chondrocyte implantation for the treatment of articular cartilage defects of the femoral condyles of the knee results in significantly better clinical outcome at 36 months in a r and omized trial compared with MF . Time to treatment and chondrocyte quality were shown to affect outcome BACKGROUND The optimal treatment for cartilage lesions has not yet been established . The objective of this r and omized trial was to compare autologous chondrocyte implantation with microfracture . This paper represents an up date , with presentation of the clinical results at five years . METHODS Eighty patients who had a single chronic symptomatic cartilage defect on the femoral condyle in a stable knee without general osteoarthritis were included in the study . Forty patients were treated with autologous chondrocyte implantation , and forty were treated with microfracture .  We used the International Cartilage Repair Society , Lysholm , Short Form-36 , and Tegner forms to collect clinical data , and radiographs were evaluated with use of the Kellgren and Lawrence grading system . RESULTS At two and five years , both groups had significant clinical improvement compared with the preoperative status . At the five-year follow-up interval , there were nine failures ( 23 % ) in both groups compared with two failures of the autologous chondrocyte implantation and one failure of the  microfracture  treatment at two years . Younger patients did better in both groups . We did not find a correlation between histological quality and clinical outcome . However , none of the patients with the best- quality cartilage ( predominantly hyaline ) at the two-year mark had a later failure . One-third of the patients in both groups had radiographic evidence of early osteoarthritis at five years . CONCLUSIONS Both methods provided satisfactory results in 77 % of the patients at five years . There was no significant difference in the clinical and radiographic results between the two treatment groups and no correlation between the histological findings and the clinical outcome . One-third of the patients had early radiographic signs of osteoarthritis five years after the surgery . Further long-term follow-up is needed to determine if one method is better than the other and to study the progression of osteoarthritis Objective : To compare the respective performance and effectiveness of autologous chondrocyte implantation ( ACI ) and mosaicplasty at resurfacing local full-thickness chondral defects of the knee . Design : R and omized clinical trial . Setting : Multicenter trial at orthopedic clinics and university hospitals conducted from 1997 to 2000 . Patients : A population of patients selected according to eligibility criteria of age , traumatic origin of the defect , its localization , size , and gravity , and above all , no previous surgical treatment of the lesion . Forty-seven patients were r and omly assigned to ACI or mosaicplasty  and subjected to arthroscopic debridement of the lesion at the time of enrollment . They were called for surgery 6 months after the initial debridement . Main Outcome : Improved knee functionality as assessed by repeated clinical evaluation based on the International Knee Documentation Committee Scale and the Lysholm Knee Scoring Scale . Results : Fourteen patients ( 31.8 % ) experienced substantial improvement following the initial debridement and , being clinical ly cured , received no further treatment . Seven patients ( 15.9 % ) were lost to follow-up . Among the 23 patients ( 52.3 % ) who could effectively be evaluated , a complete recovery ( ie , Lysholm Knee Scoring Scale score , 90 - 100 ) was observed upon clinical examination in 88 % of the mosaicplasty-treated patients and in 68 % of the ACI-treated ones ( P = 0.093 ) . Conclusions : Although the low power of our study prevents definitive conclusions , ACI and mosaicplasty are cartilage repair techniques that are clinical ly equivalent and similar in performance . The high percentage of spontaneous improvement ( ⅓ of the patients ) observed after simple debridement calls into question the need for prompt surgical treatment of patients with lesions similar to those included in this clinical trial . Moreover , this finding warrants further investigation , ideally through r and omized clinical trials in which patients subjected to debridement alone are compared with patients undergoing reconstructive surgery INTRODUCTION The treatment of full-thickness cartilage defects still represents a problem that has not yet been solved satisfactorily . Current methods used to cover defects in the knee joint are osteochondral cylinder transplantation ( OCT ) and autologous chondrocyte transplantation ( ACT ) . METHODS With a prospect i ve clinical investigation , at the time being with 2-year results , we have examined ACT in comparison to OCT in 20 patients with regard to clinical and histomorphological ( histology , immunohistochemistry , RES ) outcome . RESULTS We found equally good results with both methods in Lysholm , Meyers and Tegner Activity Scores . Histomorphologic evaluation of biopsies obtained by arthroscopy after ACT showed a defect filling in all cases , mainly with fibrous cartilage , while localized areas of hyalinelike regenerative cartilage were documented near the base . We did not see any histomorphologically visible change in the transplants after OCT . CONCLUSION At the time we prefer OCT instead of ACT given the correct indication Autologous chondrocyte implantation ( ACI ) and mosaicplasty are methods of treating symptomatic articular cartilage defects in the knee . This study represents the first long-term r and omised comparison of the two techniques in 100 patients at a minimum follow-up of ten years . The mean age of the patients at the time of surgery was 31.3 years ( 16 to 49 ) ; the mean duration of symptoms pre-operatively was 7.2 years ( 9 months to 20 years ) . The lesions were large with the mean size for the ACI group being 440.9 mm(2 ) ( 100 to 1050 ) and the mosaicplasty group being 399.6 mm(2 ) ( 100 to 2000 ) . Patients had a mean of 1.5 previous operations ( 0 to 4 ) to the articular cartilage defect . Patients were assessed using the modified Cincinnati knee score and the Stanmore-Bentley Functional Rating system . The number of patients whose repair had failed at ten years was ten of 58 ( 17 % ) in the ACI group and 23 of 42 ( 55 % ) in the mosaicplasty group ( p < 0.001 ) . The functional outcome of those patients with a surviving graft was significantly better in patients who underwent ACI compared with mosaicplasty ( p = 0.02 ) Background Many surgical techniques , including microfracture , periosteal and perichondral grafts , chondrocyte transplantation , and osteochondral grafts , have been studied in an attempt to restore damaged articular cartilage . However , there is no consensus regarding the best method to repair isolated articular cartilage defects of the knee . Questions / purpose sWe compared postoperative functional outcomes , followup MRI appearance , and arthroscopic examination after microfracture ( MF ) , osteochondral autograft transplantation ( OAT ) , or autologous chondrocyte implantation ( ACI ) . Methods We prospect ively investigated 30 knees with MF , 22 with OAT , and 18 with ACI .  Minimum followup was 3 years ( mean , 5 years ; range , 3–10 years ) . We included only patients with isolated cartilage defects and without other knee injuries . The three procedures were compared in terms of function using the Lysholm knee evaluation scale , Tegner activity scale , and Hospital for Special Surgery ( HSS ) score ; modified Outerbridge cartilage grade s using MRI ; and International Cartilage Repair Society ( ICRS ) repair grade using arthroscopy . Results All three procedures showed improvement in functional scores . There were no differences in functional scores and postoperative MRI grade s among the groups . Arthroscopy at 1 year showed excellent or good results in 80 % after MF , 82 % after OAT , and 80 % after ACI . Our study did not show a clear benefit of either ACI or OAT over MF . Conclusions Owing to a lack of superiority of any one treatment , we believe MF is a reasonable option as a first-line therapy given its ease and affordability relative to ACI or OAT.Level of Evidence Level II , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence BACKGROUND New methods have been used , with promising results , to treat full-thickness cartilage defects . The objective of the present study was to compare autologous chondrocyte implantation with microfracture in a r and omized trial . We are not aware of any previous r and omized studies comparing these methods . METHODS Eighty patients without general osteoarthritis who had a single symptomatic cartilage defect on the femoral condyle in a stable knee were treated with autologous chondrocyte implantation or microfracture  ( forty in each group ) . We used the International Cartilage Repair Society , Lysholm , Short Form-36 ( SF-36 ) , and Tegner forms to collect data . An independent observer performed a follow-up examination at twelve and twenty-four months . Two years postoperatively , arthroscopy with biopsy for  histological evaluation was carried out . The histological evaluation was done by a pathologist and a clinical scientist , both of whom were blinded to each patient 's treatment . RESULTS In general , there were small differences between the two treatment groups . At two years , both groups had significant clinical improvement . According to the SF-36 physical component score at two years postoperatively , the improvement in the microfracture group was significantly better than that in the autologous chondrocyte implantation group ( p = 0.004 ) . Younger and more active patients did better in both groups . There were two failures in the autologous chondrocyte implantation group and one in the microfracture group . No serious complications were reported . Biopsy specimens were obtained from 84 % of the patients , and histological evaluation of repair tissues showed no significant differences between the two groups . We did not find any association between the histological quality of the tissue and the clinical outcome according to the scores on the Lysholm or SF-36 form or the visual analog scale . CONCLUSIONS Both methods had acceptable short-term clinical results . There was no significant difference in macroscopic or histological results between the two treatment groups and no association between the histological findings and the clinical outcome at the two-year time-point . LEVEL OF EVIDENCE Therapeutic study , Level I-1a ( r and omized controlled trial [ significant difference ] ) . See Instructions to Authors for a complete description of levels of evidence Background As the natural healing capacity of damaged articular cartilage is poor , joint surface injuries are a prime target for regenerative medicine . Characterized chondrocyte implantation uses an autologous cartilage cell therapy product that has been optimized for its biological potency to form stable cartilage tissue in vivo . Purpose To determine whether , in symptomatic cartilage defects of the femoral condyle , structural regeneration with characterized chondrocyte implantation is superior to repair with microfracture . Study Design R and omized controlled trial ; Level of evidence , 1 . Methods Characterized chondrocyte implantation was compared with microfracture in patients with single grade III to IV symptomatic cartilage defects of the femoral condyles in a multicenter trial . Patients aged 18 to 50 years were r and omized to characterized chondrocyte implantation  ( n = 57 ) or  microfracture  ( n = 61 ) . Structural repair was blindly assessed in biopsy specimens taken at 1 year using ( 1 ) computerized histomorphometry and ( 2 ) evaluation of overall histological components of structural repair . Clinical outcome was measured using the self administered Knee injury and Osteoarthritis Outcome Score . Adverse events were recorded throughout the study . Results Characterized chondrocyte implantation result ed in better structural repair , as assessed by histomorphometry ( P = .003 ) and overall histologic evaluation ( P = .012 ) . Aspects of structural repair relating to chondrocyte phenotype and tissue structure were superior with characterized chondrocyte implantation . Clinical outcome as measured by the Knee injury and Osteoarthritis Outcome Score at 12 to 18 months after characterized chondrocyte implantation was comparable with microfracture at this stage . Both treatment groups had a similar mean baseline overall Knee injury and Osteoarthritis Outcome Score ( 56.30 ± 13.61 and 59.53 ± 14.95 for microfracture and characterized chondrocyte implantation , respectively ) , which increased in both groups to 70.56 ± 12.39 and 72.63 ± 15.55 at 6 months , 73.26 ± 14.66 and 73.10 ± 16.01 at 12 months , and 74.73 ± 17.01 and 75.04 ± 14.50 at 18 months , respectively . Both techniques were generally well tolerated ; the incidence of adverse events after characterized chondrocyte implantation was not markedly increased compared with that for microfracture . Conclusion One year after treatment , characterized chondrocyte implantation was associated with a tissue regenerate that was superior to that after microfracture . Short-term clinical outcome was similar for both treatments . The superior structural outcome may result in improved long-term clinical benefit with characterized chondrocyte implantation . Long-term follow-up is needed to confirm these findings Background Aging is responsible for degenerative changes in all cartilage elements , thus impairing its properties and healing potential . Most studies on surgical procedures for cartilage focus on young patients because these procedures are generally not considered suitable for older patients . Purpose To analyze the clinical outcome of cartilage lesion treatment using second-generation autologous chondrocyte implantation ( ACI ) techniques in patients more than 40 years old with no clear signs of osteoarthritis , to underst and their real potential in relation to aging , the failure rate , and complications in older patients . Study Design Case series ; Level of evidence , 4 . Methods Sixty-one patients with grade III to IV cartilaginous lesions of the condyles with no clear signs of osteoarthritis and a minimum age of 40 years were treated with second-generation ACI and prospect ively evaluated at 5 years ’ follow-up . Twenty-two patients were treated with arthroscopic Hyalograft C implantation , and 39 underwent the open Chondro-Gide MACI procedure . Results A significant improvement in both subjective and objective evaluations was observed . The International Knee Documentation Committee ( IKDC ) subjective score improved from 36.8 ± 8.4 to 68.1 ± 21.8 at the final evaluation . The failure rate was 20 % . A faster improvement was observed in the group treated with the arthroscopic Hyalograft C technique , whereas similar scores were found at the 24-month follow-up and final evaluation . Conclusion A clinical improvement was found in patients more than 40 years old , who in most cases benefited from second-generation ACI with good results lasting at medium-term follow-up . However , the results were inferior with respect to those previously found for younger population s , and the failure rate at medium-term follow-up was also higher . These findings were consistent in the 2 treatment groups . The only difference was the faster recovery when the arthroscopic approach was used
Purpose This paper aims to review the current evidence for  autologous chondrocyte implantation ( ACI )  generations relative to other treatment modalities , different cell delivery methods and different cell source application .