Introduction: Autologous chondrocyte implantation (ACI) has been used to treat patella cartilage lesions but several studies have indicated poorer results compared to lesions on the femoral condyles. This paper investigates the effectiveness of two different methods of ACI; porcine-derived collagen membrane as a cover (ACI-C) and matrix-carried autologous chondrocyte implantation (MACI). Methods: 124 patients (mean age 33.5) with symptomatic osteochondral lesions in the patella were selected to undergo either ACI (56 patients) or MACI (68 patients). 1 year following surgery patients underwent check arthroscopy to assess the graft. Functional assessment was performed pre-operatively, at 6 months and yearly by using the modified Cincinnati score (MCS). Results: 37.5% of patients experienced good or excellent clinical results according to the MCS in the ACI group compared with 69.2% in the MACI group (p = 0.0011). The mean MCS improved from 43.7 pre-operatively to 49.8 2 years following surgery in the ACI group, whereas in the MACI group the improvement was from 44.6 to 60.6 (p=0.07). Arthroscopic assessment showed a good to excellent International Cartilage Repair Society score in 89.7% of ACI-C grafts and 69.6% of MACI grafts (p = 0.08). There was a higher re-operation rate (p = 0.044) in the ACI group (29%) compared with MACI (10%). Conclusions: The results from this paper suggest that MACI is more successful in the treatment of patella cartilage lesions than ACI even though arthroscopic assessment showed the converse to be true. The higher complication and re-operation rate suggests that we should be treating such patients with MACI

Autologous chondrocyte implantation is now a recognised treatment for patients with knee pain secondary to articular cartilage defects. The initial technique involving periosteum as the cover for the implanted cells (ACI-P) has been modified to the use of a type I/III collagen membrane (ACI-C). Matrix-induced Autologous Chondrocyte Implantation (MACI) is a technique in which autologous donor chondrocytes are implanted onto the collagen membrane and then fixed into the defect with fibrin glue. We performed a prospective randomised comparison of 247 patients (126 ACI and 121 MACI). Patients' pain and function were assessed with mean follow-up of 42 months. Function was measured using the Modified Cincinnati and Stanmore Scoring systems. Arthroscopic assessment was by the ICRS classification. The influence of the size and site of the lesion, sex, age and previous knee surgery on the results was analysed. The Modified Cincinnati score showed a mean 17.5 point rise from pre-operative scores in the ACI group and 19.6 point rise in the MACI group. Pain, measured using the Visual Analogue Score, showed an improvement in both arms of the trial. Both chondrocyte implantation methods showed improvement in 86% of patients clinically and arthroscopically, with excellent and good results in 50% and fair results in 30% of patients. 20% of patients showed no improvement in function but none were worse. There were no serious complications. Limited histological analysis showed hyaline cartilage in a higher but non-significant proportion of ACI-C cases. With over 11 years' experience in the use of both forms of cartilage implantation we have established more precisely the indications for chondrocyte implantation. Although MACI is technically a more attractive option in most cases, because of ease and speed of the procedure, longer term follow-up is required to assess the longevity of ACI-C and MACI and the effect on prevention of ‘early-onset’ Osteoarthritis

MACI Cartilage Transplantation has been performed in New Zealand for the last three years for patients with isolated articular cartilage defects who have failed a microfracture technique. Ten patients have undergone this procedure. Patients were evaluated by an independent research assistant preoperatively and at 6, 12 and 24 months. Visual analogue pain score, ICRS score, WOMAC score, KOOS score, IKDC score, Tegner score and SF 36 were collected at all time points. An MRI scan was performed in all patients at 12 months. So far, ten patients have a minimum of 12 month data, while two have been followed to 12 months. There has been an improvement in visual analogue pain score, ICRS score, WOMAC score, KOOS score, IKDC score and SF 36. No procedures have failed. All MRI scans showed restoration of articular cartilage. In conclusion, early results are encouraging. The rehabilitation is long, thus 12 month data do not give an accurate outcome measure. Ongoing evaluation is occurring

MACI Cartilage Transplantation has been performed in New Zealand for the last five years for patients with isolated articular cartilage defects who have failed a microfracture technique. Thirteen patients have undergone this procedure. Patients were evaluated by an independent research assistant preoperatively and at 6 months, 1, 2, 3 and 5 years Visual analogue pain score, ICRS score, WOMAC score, KOOS score, IKDC score and SF 36 were collected at all time points. An MRI scan was performed in all patients at all time periods. Biopsies are taken at three years. There is an improvement in visual analogue pain score, ICRS score, WOMAC score, KOOS score, IKDC score and SF 36 at all time points. Results improve with time. No procedures have failed. All MRI scans showed restoration of articular cartilage. Histology shows hyaline like cartilage. Medium term results are encouraging. The rehabilitation is long thus 12 month data does not give an accurate outcome measure. Ongoing evaluation is occurring

The management of failed autologous chondrocyte implantation (ACI) and matrix-assisted autologous chondrocyte implantation (MACI) for the treatment of symptomatic osteochondral defects in the knee represents a major challenge. Patients are young, active and usually unsuitable for prosthetic replacement. This study reports the results in patients who underwent revision cartilage transplantation of their original ACI/MACI graft for clinical or graft-related failure. We assessed 22 patients (12 men and 10 women) with a mean age of 37.4 years (18 to 48) at a mean of 5.4 years (1.3 to 10.9). The mean period between primary and revision grafting was 46.1 months (7 to 89). The mean defect size was 446.6 mm. 2. (150 to 875) and they were located on 11 medial and two lateral femoral condyles, eight patellae and one trochlea. . The mean modified Cincinnati knee score improved from 40.5 (16 to 77) pre-operatively to 64.9 (8 to 94) at their most recent review (p < 0.001). The visual analogue pain score improved from 6.1 (3 to 9) to 4.7 (0 to 10) (p = 0.042). A total of 14 patients (63%) reported an ‘excellent’ (n = 6) or ‘good’ (n = 8) clinical outcome, 5 ‘fair’ and one ‘poor’ outcome. Two patients underwent patellofemoral joint replacement. This study demonstrates that revision cartilage transplantation after primary ACI and MACI can yield acceptable functional results and continue to preserve the joint. Cite this article: Bone Joint J 2014;96-B:54–8

Articular cartilage implantation (ACI) and associated procedures (MACI = Matrix-assisted cartilage implantation) are now established treatments for osteochondral defects in the knee. The quality of repair in terms of histological appearance is frequently not known, whilst the correlation of histology results with functional outcomes remains undefined. Histological data of the quality of the repair tissue is sparse and a precise classification proved difficult. This was a single-centre, prospective study. Over 12 years (1998-2010) 406 patients that underwent articular cartilage implantation procedures at our institution (ACI = 170, MACI = 205) had biopsies taken at the 1-2 year interval, in order to assess whether these contained ‘hyaline-like’ cartilage, ‘mixed hyaline-like with fibrocartilage’, fibrocartilage or fibrous tissue alone. Histological sections of the biopsies were prepared and stained with haematoxylin, eosin and proteoglycan stains and viewed under polarised light. All biopsies were studied by a single histopathologist in a specialist, dedicated musculoskeletal laboratory. All patients were assessed by the Cincinnati, Bentley and Visual Analogue scores both pre-operatively and at the time of the review. The findings revealed that 56 patients healed with ‘hyaline-like’ cartilage (14.9%), 103 with ‘mixed’ (27.5%), 179 with fibrocartilage (47.7%) and 37 with fibrous tissue (9.9%). These findings showed that 42.4% of defects were filled with ‘hyaline-like’ or ‘mixed’ cartilage, with 70% of these achieving a ‘fair’ to ‘excellent’ functional outcome. This was also observed in the fibrocartilage group, where 72% achieved similar results. Predictably 89% of the patients that healed by fibrous tissue had a poor functional outcome. This study shows that 71% of patients whose osteochondral defects healed by either ‘hyaline-like’, ‘mixed’ or fibrocartilage experienced an improvement in the function. In contrast, only 11% of the patients whose defects filled with fibrous tissue, showed some functional improvement. Additionally, this data indicates the advantage of biopsies in assessing the overall results of cartilage implantation procedures

Introduction: Osteochondral lesions of the Talar Dome(OCD) remain a difficult therapeutic problem. One solution has been to consider using autologous chondrocyte implants. Though initial results of this technique are interesting the donor sites have always been in a normal knee. The presence of knee symptoms subsequently in some patients might be regarded as inevitable. This paper reports on the viabilty of donor material taken from the ankle.

Materials: Twenty four patients have been recruited to a pilot study of the viability of obtaining donated chondral material for Matrix Autologous Condrocyte Implantation. There were 14 men and 10 women. Their mean age was 37.3 years (range 17–63). All were complaining of presistent symptoms of pain and some insecurity following previous conventional surgery for treatment of a symptomatic OCD. All had MRI evidence of ongoing changes in keeping with persistent problems related to an OCD.

Methods: All patients had an initial arthroscopy of the affected ankle to reassess the state of the joint surface. Donor articular cartilage was obtained from one of three sites. The anterior part of the joint surface on the talar neck, from the medial articular facet of the talus or rarely from an area of articular cartilage on the edge of the lesion. The mean weight of the donor harvest was 133 micrograms(range51–450).

Results: All donated graft material produced viable implantable graft material between 5 and 7 weeks from harvest. Cell counts ranged from 12.3 million to 20 million with cell viabilities of 98% or above. These figures are directly comparable with the results obtained from the knee despite the original donor weights being less.

Conclusion: If this technique is contemplated the use of the affected ankle as a donor site is a viable alternative to the knee.

Matrix-induced autologous chondrocyte implantation (MACI) is an established technique used to treat osteochondral lesions in the knee. For larger osteochondral lesions (> 5 cm²) deeper than approximately 8 mm we have combined the use of two MACI membranes with impaction grafting of the subchondral bone. We report our results of 14 patients who underwent the ‘bilayer collagen membrane’ technique (BCMT) with a mean follow-up of 5.2 years (2 to 8). There were 12 men and two women with a mean age of 23.6 years (16 to 40). The mean size of the defect was 7.2 cm² (5.2 to 12 cm²) and were located on the medial (ten) or lateral (four) femoral condyles. The mean modified Cincinnati knee score improved from 45.1 (22 to 70) pre-operatively to 82.8 (34 to 98) at the most recent review (p < 0.05). The visual analogue pain score improved from 7.3 (4 to 10) to 1.7 (0 to 6) (p < 0.05). Twelve patients were considered to have a good or excellent clinical outcome. One graft failed at six years.

The BCMT resulted in excellent functional results and durable repair of large and deep osteochondral lesions without a high incidence of graft-related complications.

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 prospective, randomised 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 resulted 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 assessments 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

Symptomatic articular cartilage defects are one of the most common knee injuries, arising from acute trauma, overuse, ligamentous instability, malalignment, meniscectomy, osteochondritis dissecans. Surgical treatment options include bone marrow–stimulating techniques such as abrasion arthroplasty and microfracture, osteochondral mosaicplasty, corrective osteotomy, cartilage resurfacing techniques and tissue engineering techniques using combinations of autologous cells (chondrocytes and mesenchymal stem cells), bioscaffolds, and growth factors. Matrix induced autologous chondrocyte implantation (MACI) is considered the most surgically simple form of autologous chondrocyte implantation. Our group has involved in the development of MACI since 2000 and has led to the FDA approval of MACI as the first tissue engineering product for cartilage repair in 2016. In this article, we have documented the characterisation of autologous chondrocytes, the surgical procedure of MACI and the long term clinical assessment (15 years) of patients with treatment of MACI. We have also reported the retrospective survey in patients with MACI in Australia. Our results suggest that MACI has gained good to excellent long term clinical outcome and probably can delay total knee replacement. However, restoration of hyaline-like cartilage by MACI may be interrupted by the osteoarthritic condition of the joint in patients with progressed osteoarthritis. In addition, because articular cartilage and subchondral bone are considered a single functional unit that is essential for joint function, many cartilage repair technologies including MACI and microfractures have failed short to address the functional barrier structure of osteochondral unit. Further studies are required to develop tissue engineering osteochondral construct that is able to fulfil the function of articular cartilage-subchondral bone units

Introduction: Initial results for the management of osteochondral defects with both ACI-C and MACI have been encouraging, showing significant clinical improvement. This single-centre study set out to determine any significant difference in outcomes between ACI-C and MACI. Aim: Reporting three year follow up of clinical and arthroscopic assessment of prospective analysis of ACI-C and MACI used in the management of symptomatic, full-thickness chondral and osteochondral defects in the knee. Method: Following assessment arthroscopy and harvesting of chondrocytes for culture, patients were randomised into the ACI-C or MACI arm and underwent their respective procedures one month later. In ACI-C a covered technique is employed using a porcine-derived type I/III collagen membrane sutured in place; MACI requires cultured autologous chondrocytes to be seeded in a bi-layered type I/III collagen membrane which is glued into position. An arthroscopy was performed at 12 and 24 months postprocedure to assess graft coverage and biopsies taken to determine extent of hyaline, mixed and fibro-cartilage proliferation. Results: 102 patients underwent either ACI-C (44) or MACI (58) with an average age of 33.6 (14–52). Mean Cincinnati knee rating scores recorded prior to assessment arthroscopy for ACI-C: 45.2 (10 – 94) and MACI: 45.5 (10 – 90) showed improvement at follow up with 63% of patients in the ACI-C group scoring good or excellent at three years, and 60% in the MACI group. ICRS arthroscopy scores were good or excellent in 91.4% of ACI-C and 76.1% of MACI patients at 24 months. Biopsies of the transplants at 24 months revealed proliferation of hyaline and mixed cartilage (hyaline and fibro-cartilage) in 48.6% of the ACI-C and 30.5% of the MACI patients. Conclusion: Results to date suggest significant clinical and arthroscopic improvement following ACI-C and MACI, with evidence of proliferation of hyaline cartilage at the transplant site. Limited differences are noted between the outcomes of the two techniques

Autologous chondrocyte implantation (ACI) is a technique used for the treatment of symptomatic osteochondral defects of the knee. A variation of the original periosteum membrane technique is the matrix-induced autologous chondrocyte implantation (MACI) technique. The MACI membrane consists of a porcine type-I/III collagen bilayer seeded with chondrocytes. Osteochondral defects deeper than 8 to 10 mm usually require bone grafting either before or at the time of transplantation of cartilage. We have used a variation of Peterson’s ACI-periosteum sandwich technique using two MACI membranes with bone graft which avoids periosteal harvesting. The procedure is suture-free and requires less operating time and surgical exposure. We performed this MACI-sandwich technique on eight patients, five of whom were assessed at six months and one year post-operatively using the modified Cincinnati knee, the Stanmore functional rating and the visual analogue pain scores. All patients improved within six months with further improvement at one year. The clinical outcome was good or excellent in four after six months and one year. No significant graft-associated complications were observed. Our early results of the MACI-sandwich technique are encouraging although larger medium-term studies are required before there is widespread adoption of the technique

Background: Autologous Chondrocyte Implantation (ACI) is widely used 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/III collagen as a cover (ACI-C), and the use of a collagen bilayer seeded with chondrocytes (MACI). Aim: To determine whether differences in clinical, arthroscopic and histological outcomes at 1 year exist between ACI-C and MACI techniques. Methods: We have performed a prospective randomised comparison of ACI-C versus MACI for the treatment of symptomatic chondral defects of the knee on 91 patients of whom 44 received ACI-C and 47 received MACI grafts. Results: Both treatments resulted in improvements of clinical scores after 1 year. Mean modified Cincinnati knee scores increased by 17.5 in the ACI-C group and 19.6 in the MACI group (p> 0.05). Arthroscopic assessments performed after 1 year demonstrated good to excellent ICRS graft repair scores in 79% of ACI-C grafts and 67% of MACI grafts. Hyaline-like or hyaline-like cartilage with fibrocartilage was found in the biopsies of 43% of ACI-C grafts and 36% of MACI grafts after 1 year. The rate of graft hypertrophy was 9% in the ACI-C group and 6% in the MACI group. The frequency of re-operation was 9% in each group. Conclusions: We conclude that clinical, arthroscopic and histological outcomes are comparable for both ACI-C and MACI techniques. While the MACI technique is technically attractive, further long-term studies are required before widespread adoption of this new technique

Introduction: Initial results for the management of osteochondral defects with both ACI-C and MACI have been encouraging, showing significant clinical improvements. This study set out to report the functional, clinical and histological outcomes in our institution following nine years experience of cartilage-cell transplants. Aim: Reporting results of nine-year experience of clinical and arthroscopic assessment in the use of ACI and five year experience of MACI in the management of symptomatic, full-thickness chondral and osteochondral defects in the knee. Method: Following preoperative functional assessments, arthroscopic harvesting of chondrocytes for culture was performed and patients underwent ACI-C or MACI. In ACI-C a covered technique is employed using a porcine-derived type I/III collagen membrane sutured in place; MACI requires cultured autologous chondrocytes to be seeded in a bi-layered type I/III collagen membrane which is glued into position. An arthroscopy was performed between 12 and 24 months post-procedure to assess graft coverage and biopsies taken to determine extent of hyaline, mixed and fibro-cartilage proliferation. Results: 354 patients underwent either ACI-C (103) or MACI (251) with an average age of 31.3 (15–54). Cincinnati knee rating scores recorded prior to assessment arthroscopy for ACI-C: 58.6 (12 – 92) and MACI: 48.4 (11 – 90) showed improvement at follow up with means of 84.0 for ACI-C, with 78% of patients scoring good or excellent at nine years, and a mean of 82.3% in the MACI group at five years, with 87% of patients recording good or excellent scores; statistically significant improvement was also noted in Bentley Functional score. Biopsies of the transplants taken between 12 and 24 months revealed proliferation of hyaline and mixed cartilage (hyaline and fibro-cartilage) in 47% patients; the later the biopsy was taken post-implantation, it was more likely to reveal hyaline tissue. Conclusion: Results to date suggest significant clinical and arthroscopic improvement following ACI-C and MACI, with evidence of proliferation of hyaline cartilage at the transplant site and evidence to suggest dynamic improvement in hyaline-nature of cartilage. Limited differences are noted between the outcomes of the two techniques

Introduction. We report the initial 2 and 3 year follow-up results of this randomised controlled trial of autologous chondrocyte implantation (ACI) using porcine-derived collagen membrane as a cover (ACI-C) versus matrix-carried autologous chondrocyte implantation (MACI) for the treatment of osteochondral defects of the knee. Methods. 217 patients were randomised to have either ACI (92 patients) or MACI (125 patients). The mean age in each group was 35.1 and 33 years respectively. There were equal proportion of males and females and there was no difference in the size of lesions in each of the treatment groups. One year following surgery, patients underwent check arthroscopy (with or without biopsy) to assess the graft. Functional assessment was performed yearly by using the Modified Cincinatti Knee score, the SF-36 score, the Bentley Functional Rating Score and the Visual Analogue Score. Results. 32 patients (27 from the MACI group) were excluded from the study as they underwent additional procedures (e.g. high tibial osteotomy). In the ACI group the modified Cincinnati score increased from 45.2 pre-operatively to 56.7, 54.1, and 65.4 at 1 year, 2 years and 3 years respectively. In the MACI group the Cincinnati scores increased from 45.5 pre-operatively to 59.9, 58.9, and 63.4. Arthroscopic assessment showed a good to excellent International Cartilage Repair Society score in 91.4% of ACI-C grafts and 76.1% of MACI grafts. Hyaline-like cartilage or hyaline-like with fibrocartilage was found in biopsies of 48.6% of ACI-C grafts and 30.5% of MACI grafts. Conclusions. ACI grafts are more likely to produce hyaline-like or mixed hyaline-like cartilage and fibrocartilage with better ICRS grades than MACI grafts. However, this does not translate to a better functional outcome. More importantly, ACI and MACI had similar results that were maintained at 3 years

Purpose. We report on minimum 2 year follow-up results of 71 patients randomised to autologous chondrocyte implantation (ACI) using porcine-derived collagen membrane as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) for the treatment of osteochondral defects of the knee. Introduction. 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. Results. 71 patients with a mean age of 33 years (15-48) were randomised to undergo either an ACI-C or a MACI. 37 had ACI-C and 34 MACI. The mean size of the defect was 5.0cm2. Mean duration of symptoms was 104.4 months (9-456). Mean follow-up was 33.5 months (24-45). Functional assessment using the modified Cincinnati knee score, the Bentley functional rating score and the visual analogue score was carried out. Assessment using the modified Cincinnati knee score showed a good to excellent result in 57.1% of patients followed up at 2 years, and 65.2% at 3 years in the ACI-C group; and 63.6% of patients at 2 years, and 64% at 3 years in the MACI group. Arthroscopic assessments showed a good to excellent International Cartilage Repair Society score in 81.8% of ACI-C grafts and 50% of MACI grafts. Hyaline-like cartilage or hyaline-like cartilage with fibrocartilage was found in biopsies of 56.3% of the ACI-C grafts and 30% of the MACI grafts after 2 years. Conclusion. At this stage of the trial we conclude that the clinical, arthroscopic and histological outcomes are comparable for both ACI-C and MACI

Introduction: 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 report the minimum 2 year follow-up results of 192 patients randomised to autologous chondrocyte implantation (ACI) using porcine-derived collagen membrane as a cover (ACI-C) and matrix-induced autlogous chondrocyte implantation (MACI) for the treatment of osteochondral decfects of the knee. Methods: 192 patients (mean age 34.2) were randomised to have either ACI (86 patients) or MACI (106 patients). 1 year following surgery patients underwent check arthroscopy (with or without biopsy) to assess the graft. Functional assessment was performed yearly by using the modified Cincinatti knee score, the Bentley functional rating score and the visual analogue score. Results: 24 patients were excluded from the study as they underwent additional procedures (e.g. high tibial osteotomy). In the ACI group the modified Cincinatti score increased from 42.5 pre-operatively to 56.7, 54.1, and 60.4 at 1 year, 2 years and 3 years respectively. In the MACI group the Cincinatti scores increased from 46.0 pre-operatively to 59.9, 58.9, and 58.4. Arthroscopic assessment showed a good to excellent International Cartilage Repair Society score in 90.7% of ACI-C grafts and 68.4% of MACI grafts. Hyaline-like cartilage or hyaline-like with fibrocartilage was found in biopsies of 51.9% of ACI-C grafts and 25.9% of MACI grafts. Conclusions: ACI grafts are more likely to produce hyaline-like or mixed hyaline-like cartilage and fibro-cartilage with better ICRS grades than MACI grafts. However, this does not translate to better a clinical functional outcome. More importantly, ACI and MACI had similar results that were maintained at 3 years

Purpose: We report on minimum 2 year follow-up results of 71 patients randomised to autologous chon-drocyte implantation (ACI) using porcine-derived collagen membrane as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) for the treatment of osteochondral defects of the knee. Introduction: 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 autolo-gous chondrocyte implantation (MACI) using a collagen bilayer seeded with chondrocytes. Results: 71 patients with a mean age of 33 years (15–48) were randomised to undergo either an ACI-C or a MACI. 37 had ACI-C and 34 MACI. The mean size of the defect was 5.0cm2. Mean duration of symptoms was 104.4 months (9–456). Mean follow-up was 33.5 months (24–45). Functional assessment using the modified Cincinnati knee score, the Bentley functional rating score and the visual analogue score was carried out. Assessment using the modified Cincinnati knee score showed a good to excellent result in 57.1% of patients followed up at 2 years, and 65.2% at 3 years in the ACI-C group; and 63.6% of patients at 2 years, and 64% at 3 years in the MACI group. Arthroscopic assessments showed a good to excellent International Cartilage Repair Society score in 81.8% of ACI-C grafts (22 patients) and 50% of MACI grafts (6 patients). Fisher’s exact test showed a p value of p=0.35 (not statistically significant). Hyaline-like cartilage or hyaline-like cartilage with fibrocartilage was found in biopsies of 56.3% of the ACI-C grafts (9 out of 16 patients) and 30% of the MACI grafts (3 out of 10 patients) after 2 years. Fisher’s exact test showed a p value of p=0.25 (not statistically significant). Conclusion: At this stage of the trial we conclude that the clinical, arthroscopic and histological outcomes are comparable for both ACI-C and MACI

Introduction and Aims: The treatment of cartilage defects has been revolutionised by the introduction of autologous chondrocyte implantation (ACI) over the last decade. Several studies have shown superior clinical and histological results compared to traditional treatments such as mosaicplasty. ACI involves injecting chondrocytes into the defect and sealing it with periosteum or chondroguide membrane. Recently, a new technique has been introduced which allows chondrocytes to be embedded within a matrix which is then used to fill the cartilage defect. The aim is to assess the early functional, clinical and histological results of MACI for the treatment of full-thickness cartilage defects. Method: This is a prospective study. Fifty patients, mean age 34 (range 19–62) underwent MACI for their cartilage repair. The modified Cincinnati, Brittberg and Lysholm and Gillquist scores were used to assess functional outcome. These were compared with the results obtained in 40 patients; mean age 31 (range 15–51) treated with ACI. A review of the histology in both groups was carried out. Results: At two-year follow-up, functional assessment using the Brittberg and modified cincinnati scoring systems, as well as objective clinical assessment, showed that more than 75% of patients had good or excellent results following treatment with either ACI or MACI. There was no statistical difference in the functional scores between the two groups (p < 0.05). Histological results were similar in both groups. Conclusion: Our prospective study has shown that results of MACI are comparable to that obtained by ACI. Additional advantages of the MACI technique being a shorter operative time, easier technique and potential to treat larger defects

Introduction. The treatment of distal femoral cartilage defects using autologous chondrocyte implantation (ACI) and matrix-guided autologous chondrocyte implantation (MACI) is become increasingly common. This prospective 7-year study reviews and compares the clinical outcome of ACI and MACI. Methods. We present the clinical outcomes of 159 knees (156 patients) that have undergone autologous chondrocyte implantation from July 1998. One surgeon performed all operations with patients subsequently assessed on a yearly basis using 7 independent validated clinical, functional and satisfaction rating scores. Results. Modified Cincinnati, Patient Functional Outcome and Lysholm & Gilchrist clinical rating scores all showed significant improvements compared to pre-operative levels (p<0.0001). Although ACI scores are superior at one year (p<0.05) there is no significant difference between ACI and MACI at 2 years. Visual Analogue Score and Bentley Functional rating score showed significant improvements compared to pre-operative levels (p<0.0001) with ongoing yearly sequential improvement. Patient Rating and Brittberg scores, both subjective patient scores, similarly showed continuing improvements in the years following surgery. Discussion. ACI and MACI produce significant improvements in knee function when compared to pre-operative levels with continued sequential improvement in outcomes for up to seven years. The initial data suggests a superior rate of clinical improvement using the MACI technique