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

Stratification is required to ensure that only those patients likely to benefit, receive Autologous Chondrocyte Implantation (ACI); ideally by assessing a biomarker in the blood. This study aimed to assess differences in the plasma proteome of individuals who respond well or poorly to ACI. Isobaric tag for relative and absolute quantitation (ITRAQ) mass spectrometry and label-free proteomics analyses were performed in tandem as described previously by our group (Hulme et al., 2017; 2018; 2021) using plasma collected from ACI responders (n=10) compared with non-responders (n=10) at each stage of surgery (Stage I, cartilage harvest and Stage II, cell implantation). iTRAQ using pooled plasma detected 16 proteins that were differentially abundant at baseline in ACI responders compared with non-responders (n=10) (≥±2.0 fold; p<0.05). Responders demonstrated a mean Lysholm (patient reported functional score from 0–100) improvement of 33±13 and non-responders a mean worsening of −13±13 points. The most pronounced plasma proteome shift was seen in response to Stage I surgery in ACI non-responders, with 48 proteins being differentially abundant between the two surgical procedures. We have previously noted this marked shift in response to initial surgery in the SF of ACI non-responders, several of these proteins were associated with the Acute Phase Response. One of these proteins, clusterin, could be confirmed in patients’ plasma using an independent immunoassay using individual samples. Label-free proteomic data from individual samples identified only cartilage acidic protein-1 (known to associate with osteoarthritis progression) to be significantly more abundant at Stage I in the plasma of non-responders. This study indicates that proteins can be identified within the plasma that have potential use in ACI patient stratification. Further work is required to validate the findings of this discovery-phase work in larger ACI cohorts

The objectives of the study were to investigate demographic, injury and surgery/treatment-associated factors that could influence clinical outcome, following Autologous Chondrocyte Implantation (ACI) in a large, “real-world”, 20 year longitudinally collected clinical data set. Multilevel modelling was conducted using R and 363 ACI procedures were suitable for model inclusion. All longitudinal post-operative Lysholm scores collected after ACI treatment and before a second procedure (such as knee arthroplasty but excluding minor procedures such as arthroscopy) were included. Any patients requiring a bone graft at the time of ACI were excluded. Potential predictors of ACI outcome explored were age at the time of ACI, gender, smoker status, pre-operative Lysholm score, time from surgery, defect location, number of defects, patch type, previous operations, undergoing parallel procedure(s) at the time of ACI, cell count prior to implantation and cell passage number. The best fit model demonstrated that for every yearly increase in age at the time of surgery, Lysholm scores decreased by 0.2 at 1-year post-surgery. Additionally, for every point increase in pre-operative Lysholm score, post-operative Lysholm score at 1 year increased by 0.5. The number of cells implanted also impacted on Lysholm score at 1-year post-op with every point increase in log cell number resulting in a 5.3 lower score. In addition, those patients with a defect on the lateral femoral condyle (LFC), had on average Lysholm scores that were 6.3 points higher one year after surgery compared to medial femoral condyle (MFC) defects. Defect grade and location was shown to affect long term Lysholm scores, those with grade 3 and patella defects having on average higher scores compared to patients with grade 4 or trochlea defects. Some of the predictors identified agree with previous reports, particularly that increased age, poorer pre-operative function and worse defect grades predicted poorer outcomes. Other findings were more novel, such as that a lower cell number implanted and that LFC defects were predicted to have higher Lysholm scores at 1 year and that patella lesions are associated with improved long-term outcomes cf. trochlea lesions

Background. Microfracture (MF) and Autologous Chondrocyte Implantation (ACI) are used to repair symptomatic condylar cartilage defects (grade II-IV Outerbridge). Superiority of ACI to MF is still debated. The aim of the study was to conduct a systematic literature review, compare superiority of ACI versus MF in a meta-analysis and investigate the correlation between patient age and outcome of both treatments. Methods. Extended literature search was conducted (papers from January 2001 to present), looking at patient characteristics, pre- and post-operative scores and cartilage repair assessment evaluation. Methodological quality was verified through modified Coleman score and assessment bias. A fixed-effect meta-analysis was conducted, comparing post-operative standardised mean differences between ACI and MF. Pearson correlation coefficient between post-operative score and age was calculated against ACI and MF. Results. of 490 studies systematically analysed, 8 met the inclusion criteria, accounting for 255 patients treated with ACI and 259 with MF. Overall mean postoperative scores were 81.38±8.31 for ACI and 74.9±7.0 for MF, with no significant difference (p=0.13). The average modified Coleman score of the studies was 82.6, with low bias among them. The meta-analysis displayed an overall effect estimate of 0.3 favouring ACI treatment versus MF (95%CI=0.12–0.48, P=0.001). Significant heterogeneity was although observed (I2>70%). Pearson correlation coefficient calculated between mean post-operative score and mean age, surprisingly failed to indicate clear correlation for ACI (r=0.11) and MF (r=0.18) respectively. Conclusions. Minor statistically significant superiority of ACI intervention versus MF in knee cartilage repair was found, together with high levels of heterogeneity, halting the possibility to make full recommendation of ACI versus MF. Level of Evidence. Ia (systematic review and meta-analysis)

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.

Background. Autologous Chondrocyte Implantation (ACI) is frequently used to treat chondral defects in the knee with a good long-term outcome. This is contraindicatd in meniscal deficient knees. Allogenic Menicsal Transplantation (AMT) has been shown to give good symptomatic relief in meniscus deficient knees. However this is contraindicated in advanced cartilage degeneration. We hypothesized that combination of these two might be a solution for bone-on-bone arthritis in young individuals. Methods. We studied a consecutive series of 12 patients who underwent combined ACI and AMT between 1998 and 2005. Pre operative and post operative comparisons of lysholm scores were recorded. Magnetic Resonance Imaging was performed to assess the integration ACI & AMT. Arthroscopy was performed at one year for assessment and obtain biopsy for histological examination. Results. Out of the twelve patients only eleven were included as one had died at three months after surgery. The median pre-operative lysholm score was 45 which rose to 64 at one year. Magnetic Resonance Imaging showed good integration of both ACI and menisci. Most of the patients were able to lead an active lifestyle. Conclusion. The combination of both ACI & AMT could give a good result and defer a total knee replacement in young indi

We aimed to assess the long term results of patients who underwent Autologous Chondrocyte Implantation (ACI) for osteochondral lesions of the talus. Between 1998 and 2006, 28 patients underwent ACI for osteochondral lesions of the talus. All these patients were prospectively reviewed and assessed for long term results. Outcomes were assessed using satisfaction scores, Mazur ankle score and the AOFAS score, and Lysholm knee score for donor site morbidity. The 28 patients who underwent the procedure included 18 males and 10 females. Follow up ranged from 1–9 years. In all patients, there was an improvement in the Mazur and AOFAS ankle scores and the Lysholm scores showed minimal donor site morbidity. Improvement in ankle score was independent of age and gender. The better the pre-op score the less the difference in post-op ankle scores. Patients were unlikely to benefit with pre-op ankle scores over 75. The mid to long term results of ACIs in the treatment of localised, contained cartilage defects of the talus are encouraging and prove that it is a satisfactory treatment modality for symptomatic osteochondral lesions of the talus. Complications are limited. However, in view of limited number of patients, a multi-centre randomised controlled study is required for further assessment

Background. Autologous Chondrocyte Implantation (ACI) is a procedure which is gaining acceptance for the treatment of cartilage defects in the knee with good results and a long term durable outcome. Its use in other joints has been limited, mainly to the ankle. We aimed to assess the outcome of ACI in the treatment of chondral and osteochondral defects in the hip. Methods. Fifteen patients underwent ACI for chondral or osteochondral defects in the femoral head with a follow up of upto 8 years (mean of 2 years) in our institution with a mean age of 37 years at the time of operation. Pre-operatively hip function was assessed by using the Harris Hip Score and MRI. Post-operatively these were repeated at 1 year and hip scores repeated annually. Failure was defined as a second ACI to the operated lesion or a conversion to a hip resurfacing or replacement. Results. The mean pre-op Harris Hip Score (HHS) was 55 which increased to 63 at 1 year and 70 at the latest follow up. Patients who underwent ACI for cartilage defects secondary to trauma (four) were better with a mean HHS of 69 at a mean follow up of 3.5 years. Six patients underwent THR at a mean of 32 months and were classed as failures. Five patients had evidence of avascular necrosis (AVN) of the femoral head post operatively of which four AVN pre-op. Conclusion. These early results suggest that ACI could be a viable option for the treatment of isolated chondral defects in the hip. The presence of AVN or bone cysts pre-op may be a predictor of failure

We assessed 224 patients treated with Autologous Chondrocyte Implantation performed 10–20 years ago (average 12.8 years). Average age at the time of the implantation was 33.3 years. Average size of lesion was 5.3 cm2 (range 0.6–16), while 55 patients sustained multiple lesions. The participants filled out five questionnaires. Lysholm score, Tegner-Walgren, modified Cincinnati (Noyes), Brittberg score, and KOOS were assessed. In addition, the patients were asked to grade their current situation compared to their previous follow up as better, worse of unchanged. Finally, they were asked if they would do the operation again, answering with yes or no. The patients were divided into groups according to the location and characteristics of the cartilage lesions, or concomitant surgeries during the ACI. Assessment of the outcomes reveals a significant improvement in all groups, compared with the preoperative values. There is no other study assessing a cartilage treatment with such a long follow up. According to the results of that study, autologous chondrocyte implantation seems to be an effective and durable solution for the treatment of large full thickness cartilage and osteochondral lesions of the knee joint

Autologous Chondrocyte Implantation (ACI) is a technique for repair of isolated symptomatic articular cartilage defects in the young adult knee. The knee is arthroscopically assessed and a sample of cartilage is harvested from the margin of the joint, this is digested and the liberated chondrocytes expanded in culture. At subsequent arthrotomy, the articular cartilage lesion is debrided and the cells injected behind a sutured flap. A concern regarding ACI is the iatrogenic insult to non-injured healthy cartilage adjacent to that harvested for culture. Damaged cartilage around the lesion is routinely debrided and discarded at the second stage operation. The purpose of this study was to determine whether this damaged debrided cartilage could yield an adequate number of equivalent chondrocytes for ACL. Cells from 11 patients were analysed. The debrided “waste” from around the lesion was collected, enzymatically digested and the liberated chondrocytes cultured in monolayer. The cells were recovered and placed in a 3D-pellet culture in a defined medium. Chondrocytes obtained from the routine harvest of healthy cartilage were placed in a similar culture system. The two groups were compared using DNA and GAG assays, histological and immunohistochemical techniques. Chondrocytes obtained from the debrided cartilage lesion were equivalent to those obtained from the harvested healthy cartilage. Sufficient cell numbers for implantation were achieved for all patients, however cells cultured from the debrided defect in patients who had a large degenerate lesion required significantly longer in culture to attain the required number of cells. For many patients undergoing ACI, the potential iatrogenic insult to the joint cartilage of the harvesting procedure could be avoided by harvesting the damaged tissue from around the defect itself

Purpose: We attempted to identify whether patients with early evidence of osteoarthritis (OA) on their pre-operative radiographs were associated with poorer outcomes after Autologous Chondrocyte Implantation (ACI). Methods: We retrospectively reviewed radiographs of 94 consecutive patients who underwent ACI and had already had their knee function assessed according to the Modified Cincinatti Score 2 years following surgery. Changes were graded according to The Kellgren and Lawrence (K& L) and the Stanmore grading system. Two independent observers analysed the films to assess the reproducibility and accuracy of these grading systems for assessment of OA in the knee. Results: Patients were divided into 2 groups; Group A were patients with excellent/good outcome (52 patients), those with fair/poor outcome were Group B (42 patients).13 patients in Group A and 21 patients in Group B had radiographic evidence of OA (p< 0.025). In 34 patients who had OA (mean age 33.6) the increase in Cincinatti score following surgery was minimal (33.5 to 37.5). In 60 patients where there was no evidence of OA (mean age 33.7) the score increased from 40 to 53.4. The inter-observer variation was greater using K& L (Kappa=0.31) compared with the Stanmore grading systems (Kappa=0.72). Conclusions: Patients with early radiographic evidence of OA are unlikely to gain maximum benefit from ACI. Furthermore, we recommend the use of Stanmore grading system for the assessment of OA as it is more reproducible than the K& L grading system

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.

Abstract. Purpose. Stratification is required to ensure that only patients likely to benefit, receive Autologous Chondrocyte Implantation (ACI). At Stage I (SI), healthy cartilage is harvested from the joint and chondrocytes culture expanded before being implanted into a chondral/osteochondral defect at Stage II (SII). In ACI non-responders, there is a marked shift in the profile and abundance of proteins detectable in the synovial fluid (SF) at SII, many being associated with an acute phase response (APR). However, clinical biomarkers are easier to measure in blood than SF, so we have now performed this investigation in plasma. Methods. Isobaric tag for relative and absolute quantitation mass-spectrometry was used to assess the proteome in plasma pooled from ACI responders (mean Lysholm improvement of 33, n=10) or non-responders (mean: −13 points, n=10), collected at SI or SII surgeries. Interactome networks were generated using STRING. Plasma proteome data were compared to matched SF data, previously analysed, to identify any proteins that changed across the fluids. Clusterin concentration was quantitated (ELISA; Biotechne). Results. The most pronounced plasma proteome shift was seen in response to SI surgery in ACI non-responders (50 proteins; ±2.0FC; p<0.05). An interactome network was generated based on these proteins. Functions associated with this network included complement and coagulation cascade (FDR= 5.99×10-. 25. ). Sixteen matched proteins were differentially abundant between SI and SII in both the SF and plasma, 75% of which were APR associated proteins. These included clusterin, which was confirmed by ELISA (p=0.001). Conclusions. Changes in APR signalling between SI and SII surgeries in non-responders to ACI can be identified in plasma and SF. The APR is the body's first systemic response to trauma and surgery. Our data indicate that ACI non-responders may have a greater innate response to initial surgery, which is detectable in both their SF and plasma

Introduction: Before proceeding to long-term studies, we studied early clinical results of combined Autologous Chondrocyte Implantation (ACI) and Allogenic Meniscus Transplantation (AMT). Meniscus deficient knees develop early osteo-arthritis (OA) of the knee joint. Autologous Cartilage Implantation (ACI) is contraindicated in case of meniscus deficient knees. And on contrary the Allogenic Meniscus Transplantation (AMT) is contraindicated in cartilage defects in the knee joint. But a combination of the two procedures for bone on bone OA might be a solution for this problem. This was the main purpose of our study. Methods: We studied a consecutive series of eight patients (7 males and 1 female), with an average age= 43 years (29–58), presenting with painful secondary arthritis, due to premature loss of meniscus and chondral defect/s. Median size of the femoral defects was 8.16 cm2 and of the tibial side 2.69 cm2 All patients were treated with a combination of Autologous Chondrocyte implantation (ACI) and Allogenic Meniscus Transplantation (AMT). Chondral defects were covered with periosteum/ Chondroguide membrane, secured in place with in-vitro cultured autologous chondrocytes injected underneath the path. Meniscus placed as load-bearing washer on the surface of ACI of tibia. ACI rehabilitation protocol followed post-operatively. Assessment at the end of one year was done with self-assessed Lysholm score, histology and the MRI scan. Results: Mean pre-operaive Lysholm score was 49 (17–75). This increased to a mean of 66 (26–87) at 1 year, an average increase of 16.4 points. Average one-year satisfaction score was 3 and they were back to all active life style. Five out of eight patients showed significant functional improvement at last post-operative follow-up (2 to 6 years; mean of 3.2 years). Complications were aseptic synovitis in 3 cases. Three failures were noted showig persistant pain and swelling in one, rupture of meniscus in second and third patient had a knee replacement. Arthroscopy at 1 year showed a stable meniscus with all healed peripheral margins in all except in one case with some thinning with no evidence of rejection. Histology of meniscus showed a fibrocartilage well populated with viable cells and the peripheral zone was well vascularised and integrated with capsule. Biopsy of ACI site was predominantly of fibrocartilage with good basal integration with subchondral bone. On MRI scan, allogenic meniscus was well integrated with capsule along the line of repair, showing foci of variable signal intensities within the meniscus. There was no evidence of meniscal subluxation in all but one case showing mild extrusion. ACI graft site showed a varied appearance, with 3 grafts showing focal grade 3to 4 changes. Conclusion: Seven out of eight patients improved post-operatively at one year, in terms of pain relief and increased activity. It’s possible to combine these two techniques together. Short-term outcomes are satisfactory. We could not find any deleterious effects of combining these two techniques together. So we conclude that, this might act as a one step towards a biological knee replacement

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: 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.

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.

Background: We aim to compare our final results of Autologous Chondrocyte Implantation in full thickness articular cartilage defects of the knee with the outcome as reported in the literature. Material: 9 patients median age of 29 (range 24 to 42) were operated and assessed clinically with use of International Cartilage Repair Scoring (ICRS), VAS and oxford knee score pre operation and 3, 6, 12 months post operation. 66.6% of the patients had traumatic defect due to sport injury and was located on the medial femoral condyle. Method: Arthroscopically slivers of cartilage (300 to 500 mg) were obtained from the upper minor load-bearing area of the medial femoral condyle of the injured knee for cell culture. Implantation was performed by open procedure following periosteal cover technique and use of fibrin glue as a bioscaffold 4 weeks after the biopsy. All the patients started knee exercise with CPM from next day and allowed to bear partial weight on the operated knee for 8 weeks. Result: 3 patients still had pain after one year follow-up. One case had mosaicoplasty after 8 months, which we consider as a failure and two of them had second Arthroscopy, trimming of part of repaired cartilage. 67.2% of the patients had a good or excellent result. Conclusion: All patients showed improvement of clinical symptoms except one patient who failed at 8 months. We found our results are comparable as reported in the literature in this small cohort. This kind of surgery may be performed in a non referral hospital

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: Autologous Chondrocyte Implantation (ACI) was first described in 1994(. 1. ) and has become an increasingly widely used treatment for chondral defects in the knee. The intention of this study was to identify which patient and/or surgical factors affect clinical outcome. In order to do this, a multicentre database of patients treated with ACI was established. Methods: Four European centres collaborating in the EuroCell project (. 2. ) contributed data. These centres have historically used different outcome measures to follow up their patients. In order to analyse this data, a method of z-transformation was used to standardise the clinical scores. This has allowed a large number of patients to be investigated even when different scores have been used. A panel of predictor variables was agreed relating to patient factors and operative technique. Linear multiple regression analysis was performed to determine which predictor variables significantly influenced clinical outcome. Results: A total of 284 patient datasets from four centres were investigated with 1 to 10 year follow-up. In 213 datasets the Modified Cincinnati (Noyes) clinician evaluation was used (. 3. ). The remaining 73 patients had outcome data measured with the modified Lysholm score (. 4. ). Outcome was defined as the change in score to latest follow-up. Z-transformation (z-change) was performed for each score type. The regression model was: z-change = − 0.11 − 0.5*z-preop − 0.43*R4 + 0 .30*OC + 0.20*FC (R2=0.30) The regression analysis showed that the factors which affected outcome were one centre (R4), pre-operative score (z-preop), osteochondral defects (OC), and lesions of the femoral condyle (FC). Factors which were found not to affect outcome included the age of the patient, size of the defect treated, number of defects treated and time to follow-up. Variations in operative technique, including the location of the cartilage harvest, the use of fibrin sealant and the timing of patch placement, were not found to have an effect on clinical outcome. Conclusions: The method of z-transformation is a useful way of compiling multicentre data where different outcome measures have been used. This has allowed a large dataset to be compiled and factors which influence clinical outcome to be identified