human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Marrow stimulation techniques such as drilling or microfracture are first-line treatment options for symptomatic cartilage defects . Common knowledge holds that these treatments do not compromise subsequent cartilage repair procedures with autologous chondrocyte implantation . Hypothesis Cartilage defects pretreated with marrow stimulation techniques will have an increased failure rate . Study Design Cohort study ; Level of evidence , 2 . Methods The first 321 consecutive patients treated at one institution with autologous chondrocyte implantation for full-thickness cartilage defects that reached more than 2 years of follow-up were evaluated by prospect ively collected data . Patients were grouped based on whether they had undergone prior treatment with a marrow stimulation technique . Outcomes were classified as complete failure if more than 25 % of a grafted defect area had to be removed in later procedures because of persistent symptoms . Results There were 522 defects in 321 patients ( 325 joints ) treated with autologous chondrocyte implantation .  On average , there were 1.7 lesions per patient . Of these joints , 111 had previously undergone surgery that penetrated the subchondral bone ; 214 joints had no prior treatment that affected the subchondral bone and served as controls . Within the marrow stimulation group , there were 29 ( 26 % ) failures , compared with 17 ( 8 % ) failures in the control group . Conclusion Defects that had prior treatment affecting the subchondral bone failed at a rate 3 times that of nontreated defects . The failure rates for drilling ( 28 % ) , abrasion arthroplasty ( 27 % ) , and microfracture ( 20 % ) were not significantly different , possibly because of the lower number of microfracture patients in this cohort ( 25 of 110 marrow-stimulation procedures ) . The data demonstrate that marrow stimulation techniques have a strong negative effect on subsequent cartilage repair with autologous chondrocyte implantation and therefore should be used judiciously in larger cartilage defects that could require future treatment with autologous chondrocyte implantation Background There is no consensus about the optimal time for weightbearing activities after matrix-associated autologous chon-drocyte implantation ( MACI ) of the femoral condyle . Hypothesis A comprehensive protocol after MACI on the femoral condyle with accelerated weightbearing leads to a better functional and radiographic outcome compared with the same comprehensive protocol with delayed weightbearing . Study Design R and omized controlled trial ; Level of evidence , 1 . Methods Thirty-one patients ( 22 male , 9 female ) after MACI on the femoral condyle were r and omly assigned to the  accelerated weightbearing group ( group A ) or the  delayed weightbearing group ( group B ) . Aside from increase and time of full weightbearing , both groups adhered to the same rehabilitation protocol and exercises . Patients were assessed preoperatively and at 4 , 12 , 24 , 52 , and 104 weeks after surgery . Clinical evaluation was performed by determining the subjective form of the International Knee Documentation Committee ( IKDC ) , the Tegner activity scale , and the Knee Injury and Osteoarthritis Outcome Score ( KOOS ) . Radiological outcome was evaluated by the MOCART score and the size and amount of bone marrow edema and effusion . Results In both groups , there were no differences with regard to the clinical outcome . For the radiological outcome , group A showed a higher prevalence of bone marrow edema after 6 months without correlation to the clinical outcome ( P 5 .06-.1 ) . However , after 104 weeks , there were no differences in the radiological outcome between group A and group B. Conclusion A rehabilitation protocol with accelerated weightbearing leads to good clinical and functional outcome after 2 years without jeopardizing the healing graft Background This is a prospect i ve clinical study to assess the effectiveness of autologous chondrocyte implantation in patients who failed prior treatments for articular cartilage defects of the knee . Hypothesis Autologous chondrocyte implantation provides clinical benefit in patients with failed articular cartilage treatments . Study Design Cohort study ; Level of evidence , 2 . Methods One hundred fifty-four patients with failed treatment for articular cartilage defects of the knee received autologous chondrocyte implantation in a multicenter , prospect i ve study . Follow-up was 48 months . Outcomes included change from baseline in knee function , knee pain , quality of life , and overall health . Duration of benefit after autologous chondrocyte implantation was compared with the failed prior non — autologous chondrocyte implantation procedure . Safety information was recorded . Additional analyses were performed on the 2 major cohorts of prior procedures entered into the study , marrow-stimulation technique or debridement alone , to assess if there were any significant differences in baseline characteristics , outcomes , or prognosis between the 2 groups . Results One hundred twenty-six patients ( 82 % ) completed the protocol . Seventy-six percent of patients were treatment successes at study end , while 24 % were deemed treatment failures . Preoperative mean knee pain score was 3.0 ( SD , 1.8 ; 0 = severe , 10 = normal ) . Mean improvements were observed from baseline to all time points ( P < .001 ) for all outcome measures . Preoperative to 48-month values , respectively , were as follows : On the Knee injury and Osteoarthritis Outcome Score subscales of pain : 48.7 to 72.2 ; other symptoms : 51.8 to 70.8 ; sports/recreation : 25.8 to 55.8 ; knee quality of life : 20.9 to 52.2 ; and activities of daily living : 58.6 to 81.0 ; on the Modified Cincinnati Overall Knee score : 3.3 to 6.3 ; on the visual analog scale : 28.8 to 69.9 ; and on the SF-36 Overall Physical Health 33.0 to 44.4 . Results did not differ between patients whose primary surgery had been a marrow-stimulating procedure and those whose primary procedure had been a debridement alone . The median difference in duration of benefit between autologous chondrocyte implantation and the failed non — autologous chondrocyte implantation prior procedure was at least 31 months ( P < .001 ) . Seventy-six patients ( 49 % ) had subsequent surgical procedure(s ) , predominantly arthroscopic . Need for a subsequent surgical procedure was not predictive of failure . Conclusion Patients with moderate to large chondral lesions with failed prior cartilage treatments can expect sustained and clinical ly meaningful improvement in pain and function after autologous chondrocyte implantation . The subsequent surgical procedure rate observed in this study ( 49 % overall ; 40 % related to autologous chondrocyte implantation ) appears higher than generally reported after autologous chondrocyte implantation 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 A biodegradable , hyaluronian-based biocompatible scaffold was used for autologous chondrocyte transplantation . This prospect i ve study analyzes a clinical outcome of 70 consecutive patients treated by arthroscopic autologous chondrocyte transplantation at minimum 24 months follow up ( 47 of these patients achieved minimum 36 months follow-up and 21 patients minimum 48 months follow-up ) in order to establish clear indication criteria for this type of treatment . 31 of these patients presented isolated chondral lesions , while 39 patients with associated lesions ( 23 ACL lesions , 28 meniscal lesions , 1 varus knee ) were treated during the same surgical procedure with cartilage harvesting . A statistically significant clinical improvement was shown just at 24 months and the second-look arthroscopy demonstrated a complete coverage of the grafted area with a hyaline cartilage-like tissue in 12 of 15 analyzed patients . A better clinical outcome was observed in young , well-trained patients and in traumatic lesions . Other factors , such as defect size , localization , previous and associated surgery did not influence significantly the results . This matrix autologous chondrocyte transplantation procedure simplifies the surgical procedure and can be performed arthroscopically , thus reducing surgical morbidity and recovery time 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 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 
    Output:
    
agent
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Marrow stimulation techniques such as drilling or microfracture are first-line treatment options for symptomatic cartilage defects . Common knowledge holds that these treatments do not compromise subsequent cartilage repair procedures with autologous chondrocyte implantation . Hypothesis Cartilage defects pretreated with marrow stimulation techniques will have an increased failure rate . Study Design Cohort study ; Level of evidence , 2 . Methods The first 321 consecutive patients treated at one institution with autologous chondrocyte implantation for full-thickness cartilage defects that reached more than 2 years of follow-up were evaluated by prospect ively collected data . Patients were grouped based on whether they had undergone prior treatment with a marrow stimulation technique . Outcomes were classified as complete failure if more than 25 % of a grafted defect area had to be removed in later procedures because of persistent symptoms . Results There were 522 defects in 321 patients ( 325 joints ) treated with autologous chondrocyte implantation .  On average , there were 1.7 lesions per patient . Of these joints , 111 had previously undergone surgery that penetrated the subchondral bone ; 214 joints had no prior treatment that affected the subchondral bone and served as controls . Within the marrow stimulation group , there were 29 ( 26 % ) failures , compared with 17 ( 8 % ) failures in the control group . Conclusion Defects that had prior treatment affecting the subchondral bone failed at a rate 3 times that of nontreated defects . The failure rates for drilling ( 28 % ) , abrasion arthroplasty ( 27 % ) , and microfracture ( 20 % ) were not significantly different , possibly because of the lower number of microfracture patients in this cohort ( 25 of 110 marrow-stimulation procedures ) . The data demonstrate that marrow stimulation techniques have a strong negative effect on subsequent cartilage repair with autologous chondrocyte implantation and therefore should be used judiciously in larger cartilage defects that could require future treatment with autologous chondrocyte implantation Background There is no consensus about the optimal time for weightbearing activities after matrix-associated autologous chon-drocyte implantation ( MACI ) of the femoral condyle . Hypothesis A comprehensive protocol after MACI on the femoral condyle with accelerated weightbearing leads to a better functional and radiographic outcome compared with the same comprehensive protocol with delayed weightbearing . Study Design R and omized controlled trial ; Level of evidence , 1 . Methods Thirty-one patients ( 22 male , 9 female ) after MACI on the femoral condyle were r and omly assigned to the  accelerated weightbearing group ( group A ) or the  delayed weightbearing group ( group B ) . Aside from increase and time of full weightbearing , both groups adhered to the same rehabilitation protocol and exercises . Patients were assessed preoperatively and at 4 , 12 , 24 , 52 , and 104 weeks after surgery . Clinical evaluation was performed by determining the subjective form of the International Knee Documentation Committee ( IKDC ) , the Tegner activity scale , and the Knee Injury and Osteoarthritis Outcome Score ( KOOS ) . Radiological outcome was evaluated by the MOCART score and the size and amount of bone marrow edema and effusion . Results In both groups , there were no differences with regard to the clinical outcome . For the radiological outcome , group A showed a higher prevalence of bone marrow edema after 6 months without correlation to the clinical outcome ( P 5 .06-.1 ) . However , after 104 weeks , there were no differences in the radiological outcome between group A and group B. Conclusion A rehabilitation protocol with accelerated weightbearing leads to good clinical and functional outcome after 2 years without jeopardizing the healing graft Background This is a prospect i ve clinical study to assess the effectiveness of autologous chondrocyte implantation in patients who failed prior treatments for articular cartilage defects of the knee . Hypothesis Autologous chondrocyte implantation provides clinical benefit in patients with failed articular cartilage treatments . Study Design Cohort study ; Level of evidence , 2 . Methods One hundred fifty-four patients with failed treatment for articular cartilage defects of the knee received autologous chondrocyte implantation in a multicenter , prospect i ve study . Follow-up was 48 months . Outcomes included change from baseline in knee function , knee pain , quality of life , and overall health . Duration of benefit after autologous chondrocyte implantation was compared with the failed prior non — autologous chondrocyte implantation procedure . Safety information was recorded . Additional analyses were performed on the 2 major cohorts of prior procedures entered into the study , marrow-stimulation technique or debridement alone , to assess if there were any significant differences in baseline characteristics , outcomes , or prognosis between the 2 groups . Results One hundred twenty-six patients ( 82 % ) completed the protocol . Seventy-six percent of patients were treatment successes at study end , while 24 % were deemed treatment failures . Preoperative mean knee pain score was 3.0 ( SD , 1.8 ; 0 = severe , 10 = normal ) . Mean improvements were observed from baseline to all time points ( P < .001 ) for all outcome measures . Preoperative to 48-month values , respectively , were as follows : On the Knee injury and Osteoarthritis Outcome Score subscales of pain : 48.7 to 72.2 ; other symptoms : 51.8 to 70.8 ; sports/recreation : 25.8 to 55.8 ; knee quality of life : 20.9 to 52.2 ; and activities of daily living : 58.6 to 81.0 ; on the Modified Cincinnati Overall Knee score : 3.3 to 6.3 ; on the visual analog scale : 28.8 to 69.9 ; and on the SF-36 Overall Physical Health 33.0 to 44.4 . Results did not differ between patients whose primary surgery had been a marrow-stimulating procedure and those whose primary procedure had been a debridement alone . The median difference in duration of benefit between autologous chondrocyte implantation and the failed non — autologous chondrocyte implantation prior procedure was at least 31 months ( P < .001 ) . Seventy-six patients ( 49 % ) had subsequent surgical procedure(s ) , predominantly arthroscopic . Need for a subsequent surgical procedure was not predictive of failure . Conclusion Patients with moderate to large chondral lesions with failed prior cartilage treatments can expect sustained and clinical ly meaningful improvement in pain and function after autologous chondrocyte implantation . The subsequent surgical procedure rate observed in this study ( 49 % overall ; 40 % related to autologous chondrocyte implantation ) appears higher than generally reported after autologous chondrocyte implantation 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 A biodegradable , hyaluronian-based biocompatible scaffold was used for autologous chondrocyte transplantation . This prospect i ve study analyzes a clinical outcome of 70 consecutive patients treated by arthroscopic autologous chondrocyte transplantation at minimum 24 months follow up ( 47 of these patients achieved minimum 36 months follow-up and 21 patients minimum 48 months follow-up ) in order to establish clear indication criteria for this type of treatment . 31 of these patients presented isolated chondral lesions , while 39 patients with associated lesions ( 23 ACL lesions , 28 meniscal lesions , 1 varus knee ) were treated during the same surgical procedure with cartilage harvesting . A statistically significant clinical improvement was shown just at 24 months and the second-look arthroscopy demonstrated a complete coverage of the grafted area with a hyaline cartilage-like tissue in 12 of 15 analyzed patients . A better clinical outcome was observed in young , well-trained patients and in traumatic lesions . Other factors , such as defect size , localization , previous and associated surgery did not influence significantly the results . This matrix autologous chondrocyte transplantation procedure simplifies the surgical procedure and can be performed arthroscopically , thus reducing surgical morbidity and recovery time 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 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 
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