High Tibial Osteotomy (HTO) is a recognised method of correction for knee joint malalignment and unicom-partmental osteoarthritis. Long-term results of this technique have been reported and are favourable. Good results have also been reported with Autologous Chondrocyte Implantation (ACI-C, MACI). Malalignment, if present, should be corrected when ACI is performed. Although results have been reported for either procedure separately, the outcomes of combined HTO-ACI remain unreported. The aim of this study was to evaluate functional outcome in patients undergoing combined HTO-ACI procedures.

Twenty three patients undergoing a combined ACI-HTO procedure were identified retrospectively from a larger trial of patients undergoing ACI for symptomatic chondral defects. The mean age of the patients was 36 (28 – 49). The mean follow-up was 54 months (12 – 108) and mean defect size was 689mm2 (range 350 – 1200). Nine patients had ACI-C and HTO, the remainder having MACI and HTO. Pre and post-operative assessment was carried out using the Visual Analogue Score (VAS), the Bentley Functional Rating Score and the Modified Cincinnati Rating System.

The Mean VAS score improved from 7.4 (4 – 10) pre-operatively to 2.9 (0 – 6) post-operatively at the latest follow-up (p< 0.0001). The Bentley Functional Rating Score improved from 2.9 (2 – 4) to 1.8 (0 – 4), which was statistically significant (p< 0.0001). The Modified Cincinnati Rating System improved from 35.2 (20 – 49) pre-operatively to 68.7 (46 – 85) post-operatively (p< 0.0001). Fourteen patients underwent biopsy of the graft site at a mean of 13.7 months: 21% of biopsies were hyaline-like cartilage, 36% were mixed hyaline/fibrocartilage, 29 % were fibrocartilage and 14% were fibrous tissue.

Combining high tibial osteotomy with autologous chondrocyte implantation is an effective method of decreasing pain and increasing function in the short term. Further evaluation of this procedure is required.

Introduction: Autologous Chondrocyte Implantation (ACI) is a treatment option for symptomatic, full-thickness chondral/osteochondral injuries. Goals of surgery and rehabilitation include replacement of damaged cartilage with hyaline/hyaline-like cartilage, leading eventually to improved level of function. Intermediate and long-term results are promising in terms of functional improvement.

Purpose: To explore the hypothesis that non-hyaline cartilage repair tissue is associated with worse functional outcome and to assess whether the quality of the repair tissue formed following ACI improves with time post-surgery.

Methods and Results: Two hundred and forty eight patients who underwent ACI at our institution were studied, having had post-implantation biopsies of the repair tissue. Mean timing of biopsy was 14.8 months (range 3–55). 59 biopsies showed hyaline tissue (24%), 67 mixed hyaline and fibrocartilage (27%), 113 biopsies were fibrocartilage only (46%) and 9 patients had a fibrous tissue biopsy result (9%). 126 patients (51%) had hyaline tissue in the regenerate and demonstrated a mean Modified Cincinnati Rating Score (MCRS) of 84 and a mean Lysholm Score of 88 at last follow-up (Group 1). 122 patients (49%) had no hyaline tissue in the regenerate and scored a mean MCRS of 71 and a mean Lysholm Score of 73 (Group 2). Both Groups 1 and 2 demonstrated a statistically significant improvement in functional outcome between pre and post-operative scores (p< 0.0001). There was significant difference in post-operative scores between Groups 1 and 2 suggesting that presence of hyaline tissue in the regenerate is associated with improved functional outcome (p< 0.05). Finally, our statistical analysis suggested that if time post-implantation doubles, then the likelihood of a favourable histological outcome increases significantly.

Conclusion: ACI forms a durable repair tissue that remodels and continues to improve in quality with time. Poor functional outcome may reflect the presence of a non-hyaline cartilage repair tissue.

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.

High tibial osteotomy (HTO) is a recognised method of correction for knee joint malalignment and unicompartmental osteoarthritis. The long term results of this technique have been reported and are favourable. Autologous chondrocyte implantation (ACI-C, MACI) has also been reported to have good results It is advised that malalignment, if present, should be corrected if ACI is to be performed. Although results have been reported for either procedure separately, the outcomes of combined HTO-ACI remain unreported.

To evaluate functional outcome in a group of patients undergoing combined HTO-ACI procedures.

Twenty three patients undergoing a combined ACI-HTO procedure were identified retrospectively from a larger trial of patients undergoing ACI for symptomatic chondral defects. The mean follow-up was 54 months (range 12 – 108) and the mean defect size was 689 mm2 (range 350 – 1200). Nine patients had ACI-C and HTO, the remainder having MACI and HTO. Pre and postoperative assessment was carried out using the Visual Analogue Score (VAS), the Bentley Functional Rating Score and the Modified Cincinnati Rating System.

The Mean VAS score improved from 7.4 pre-operatively to 2.9 post-operatively (p< 0.0001). The Bentley Functional Rating Score improved from 2.9 to 1.8 (p< 0.0001) whilst the Modified Cincinnati Rating System improved from 35.2 pre-operatively to 68.7 post-operatively (p< 0.0001). There was no significant difference between ACI-C and MACI. Two patients developed a non union at a mean of 13 months and a further two patients had a failure of the chondrocyte graft at a mean of 22.5 months.

Combining high tibial osteotomy with autologous chondrocyte implantation is an effective method of decreasing pain and increasing function at mean of 54 months follow-up. Further follow-up is required to assess the long term outcomes of these combined procedures.

Introduction: Autologous Chondrocyte Implantation (ACI) is a treatment option for full-thickness chondral, or osteochondral injuries that are painful and debilitating. Goals of surgery and rehabilitation include replacement of damaged cartilage with hyaline or hyaline-like cartilage, leading eventually to improved level of function. Intermediate and long-term results are promising in terms of functional and clinical improvement.

Purpose: To explore the hypothesis that the quality of the repair tissue, formed following Autologous Chondrocyte Implantation (ACI), improves with time post-surgery.

Methods and Results: Two hundred and forty eight patients who underwent autologous chondrocyte implantation in our institution were studied after having had post implantation biopsies of the repair tissue. Mean timing of biopsy was 14.8 months (range 3–55). 59 biopsies gave hyaline tissue (24%), 67 mixed hyaline and fibrocartilage (27%), 113 biopsies were fibrocartilage only (46%) and 9 patients had a fibrous tissue biopsy result (9%). Due to NHS restraints and waiting list targets biopsies were actually performed at various time points post implantation allowing us to statistically correlate histological findings with the maturity of the repair tissue.

Our statistical analysis suggests that if time post implantation doubles then the likelihood of a favourable histological outcome increases significantly.

Conclusion: Autologous chondrocyte implantation forms a durable repair tissue that remodels and continues to improve in quality with time. It is recommended that for future research/study purposes 24 months is used as an optimal time to look at histology, since our data show that outcome is still improving until this point.

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.

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.

Orthopaedic surgeons vary in their attitude towards resurfacing of the patella in total knee arthroplasty. Few studies are available to assess outcome and patient preference. We evaluated post-operative anterior knee pain and knee preference in patients with bilateral knee replacements and unilateral patellar resurfacing.

We reviewed 30 patients who had undergone bilateral knee replacement with patellar resurfacing on only one side. Follow-up was from five to 12 years and the patients were assessed using the Knee Society rating, an anterior knee pain rating and a satisfaction score. Patients were also asked specifically if they had a preference for either knee. Assessment was performed without knowing which patella had been resurfaced.

Fourteen patients (47%) favoured the resurfaced knee, six (20%) the un-resurfaced knee and 10 (33%) had no particular preference. The overall prevalence of anterior knee pain was 50% in the un-resurfaced cases (six mild, six moderate, three severe) and 20% in the resurfaced knees (four mild, two moderate). No significant difference was found between knee scores. Three un-resurfaced patellae have been secondarily resurfaced.

This study shows a significant preference for the resurfaced side (p< 0.01), with a higher prevalence of anterior knee pain in non-resurfaced patellae (p< 0.05).

Smoking is known to have an adverse effect on wound healing and musculoskeletal conditions. This case-controlled study looked at whether smoking has a deleterious effect in the outcome of autologous chondrocyte implantation for the treatment of full thickness chondral defects of the knee.

The mean Modified Cincinatti Knee score was statistically significantly lower in smokers (n = 48) than in non-smokers (n = 66) both before and after surgery (p < 0.05). Smokers experienced significantly less improvement in the knee score two years after surgery (p < 0.05). Graft failures were only seen in smokers (p = 0.016). There was a strong negative correlation between the number of cigarettes smoked and the outcome following surgery (Pearson’s correlation coefficient −0.65, p = 0.004).

These results suggest that patients who smoke have worse pre-operative function and obtain less benefit from this procedure than non-smokers. The counselling of patients undergoing autologous chondrocyte implantation should include smoking, not only as a general cardiopulmonary risk but also because poorer results can be expected in smokers following this procedure.

Autologous chondrocyte implantation is an option in the treatment of full-thickness chondral or osteochondral injuries which are symptomatic. The goal of surgery and rehabilitation is the replacement of damaged cartilage with hyaline or hyaline-like cartilage, producing improved levels of function and preventing early osteoarthritis. The intermediate results have been promising in terms of functional and clinical improvement.

Our aim was to explore the hypothesis that the histological quality of the repair tissue formed after autologous chondrocyte implantation improved with increasing time after implantation.

In all, 248 patients who had undergone autologous chondrocyte implantation had biopsies taken of the repair tissue which then underwent histological grading. Statistical analysis suggested that with doubling of the time after implantation the likelihood of a favourable histological outcome was increased by more than fourfold (p < 0.001).

Chondral damage to the knee is common and, if left untreated, can proceed to degenerative osteoarthritis. In symptomatic patients established methods of management rely on the formation of fibrocartilage which has poor resistance to shear forces. The formation of hyaline or hyaline-like cartilage may be induced by implanting autologous, cultured chondrocytes into the chondral or osteochondral defect.

Autologous chondrocyte implantation may be used for full-thickness chondral or osteochondral injuries which are painful and debilitating with the aim of replacing damaged cartilage with hyaline or hyaline-like cartilage, leading to improved function. The intermediate and long-term functional and clinical results are promising.

We provide a review of autologous chondrocyte implantation and describe our experience with the technique at our institution with a mean follow-up of 32 months (1 to 9 years).

The procedure is shown to offer statistically significant improvement with advantages over other methods of management of chondral defects.

Introduction: Smoking is associated with impaired wound healing, delayed bony union following fractures and an adverse effect on the immune system. Furthermore, smoking is an important risk factor for the development pulmonary complications following major surgical procedures, as well as wound complications. We determined whether smoking had a deleterious effect on outcome after autologous chondrocyte implantation (ACI) in the treatment of ostechondral defects of the knee.

Methods: We identified 103 (54 females and 49 males) patients with a mean age of 34.2 (range 18 to 49) who had undergone ACI between January 2001 and August 2004 who also had their smoking status recorded. The patients were divided into 3 groups according to their smoking status. The Visual Analogue Score, Bentley Functional Rating Score and Modified Cincinatti Scores were used to assess function pre-operatively, 6 months and then yearly thereafter.

Results: Group 1 consisted of 31 smokers (mean pack years of 13.4), group 2 consisted of 63 non-smokers and group 3 contained 9 ex-smokers. In Group 1, the Modified Cincinatti Score pre-operatively, 6 months, 1 year and 2 years following surgery were 34.1, 42.6, 43.5 and 46.7 respectively. In group 2 the scores were 47.4, 59.6, 59.1, 65.3, and in group 3 the scores were 39.8, 50, 53.3, 51.8. At the 1 year check arthroscopy, the graft failure rate in group 1 was 12% and biopsies revealed mixed hyaline and fibrocartilage in only 25% (there were no patients with hyaline cartilage). There were no graft failures in group 2 and 43.8% of the biopsies performed were either hyaline (12.5%) or mixed hyaline and fibrocartilage (31.3%). The wound complication rate was 24% in group 1 and 8% in group 2.

Conclusions: The results of this study suggest that people who smoke have a worse functional outcome and a higher complication rate following chondrocyte implantation. This association has not been previously described and should be included in the pre-operative counselling of patients undergoing the procedure.

Introduction: Several studies have implicated excessive weight as a negative predictor of success of total knee arthroplasty. In addition, obese patients are known to have increased risk of wound complications after orthopaedic and general surgery. The purpose of this study was to compare the clinical and functional outcomes of autologous chondrocyte implantation for treatment of osteochondral defects of the knee performed in obese patients with those performed in non-obese patients.

Methods: We analysed the data on all our patients that have been followed up for a minimum of 2 years and had their height and weight recorded initially in our database. Functional assessment consisted of Bentley Functional Rating Score, Visual Analogue Score, and the Modified Cincinatti Scores (collected prospectively at 6 months, 1 year, 2 years and 3 years following surgery). Patients were placed into 3 groups according to their body mass index (BMI). Group A consisted of patients with BMI of 20 to 24.9, group B patients with BMI of 25 to 29.9 and Group C are patients with BMI of 30 to 39.9.

Results: There were 80 patients (41 males and 39 females) with a mean age of 35.4 (range 18 to 49). The mean BMI for the entire group was 26.6. The pre-operative, 6 month, 1 year, 2 year, and 3 year Modified Cincinatti Score in Group A (32 patients) was 54.4, 80.3, 82.7, 74.7 and 72.6. Similarly in Group B, the scores were 53, 41, 54, 56, 49.5 and in Group C the scores were 36.3, 36.3, 49.6, 36, and 35.7. The wound infection rate in Group A was 6.25%, in Group B was 17.6% and Group C was 14.3%.

Conclusions: Initial results from this study suggest that BMI is an important predictor of outcome after chondrocyte implantation. The group of patients that would gain most benefit from ACI are patients that are not overweight (defined by BMI in the range of 20 to 24.9). Further work is being carried out to support the hypothesis that surgeons should strongly consider not operating on patients unless the BMI is less than 25.

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.

Aims: he purpose of this study was to determine whether autologous chondrocyte implantation (ACI) in patients with articular cartilage defects of the knee resulted in patients returning to pre-injury levels of work and physical activities.

Methods: 133 consecutive patients from January 2001 to December 2002 underwent ACI at our institution. A telephone and postal questionnaire was conducted to ascertain a detailed occupational and leisure activity profile in this cohort of patients. For each job held for at least 2 months, we asked whether an average working day had involved any of the ten specified physical activities. Similarly, for each sport that had been played more than 5 times a year, we asked the age the sporting activities had began and whether they were able to return to these sports after surgery. Occupation for each patient was given a 3 digit code according to the Standard Occupational Classification System 2000 and hence determined whether the work performed was manual or non-manual.

Results: 97 patients responded to the questionnaire. There were 53 females and 44 males and the mean age at the time of operation was 34.5 (range 14 to 49). Category 6 (Personal Services Occupations) was the most common occupation pre-operatively, whereas category 4 (Administrative and Secretarial Occupations) was the most common post-operatively. 7% of patients’ work involved kneeling or squatting and this figure rose to 12%, 4 years following surgery. 42% of patients had to make some form of modification to their work (usually less physical or more office based). 47% of patients were able to return to at least one of the sports they played pre-injury.

Conclusion: This is the first study to demonstrate that patients are able to return to work and resume sporting activity following autologous chondrocyte implantation.

Aims: To compare the clinical and functional outcomes of autologous chondrocyte implantation for treatment of osteochondral defects of the knee performed in overweight, obese and patients of ‘ideal weight’as defined by their BMI.

Methods: We analysed the data on all our patients that have been followed up for a minimum of 2 years and had their height and weight recorded initially in our database. Functional assessment consisted of the Modified Cincinatti Scores (collected prospectively at 6 months, 1 year, 2 years and 3 years following surgery). Patients were placed into 3 groups according to their body mass index (BMI). Group A consisted of patients with BMI of 20 to 24.9, group B patients with BMI of 25 to 29.9 and Group C are patients with BMI of 30 to 39.9.

Results: There were 80 patients (41 males and 39 females) with a mean age of 35.4 (range 18 to 49). The mean BMI for the entire group was 26.6. The pre-operative, 6 month, 1 year, 2 year, and 3 year Modified Cin-cinatti Score in Group A (32 patients) was 54.4, 80.3, 82.7, 74.7 and 72.6. Similarly in Group B, the scores were 53, 41, 54, 56, 49.5 and in Group C the scores were 36.3, 36.3, 49.6, 36, and 35.7. The wound infection rate in Group A was 6.25%, in Group B was17.6% and Group C was 14.3%.

Conclusions: Initial results from this study suggest that BMI is an important predictor of outcome after chon-drocyte implantation. The group of patients that would gain most benefit from ACI are patients that are not overweight (defined by BMI in the range of 20 to 24.9). Further work is being carried out to support the hypothesis that surgeons should strongly consider not operating on patients unless the BMI is less than 25.

Aims: To investigate

the influence of histology on durability of cartilage repair following collagen-covered autologous chon-drocyte implantation (ACI-C) in the knee.

Patients and methods: The modified Cincinnati scores (MCRS) of eighty-six patients were evaluated prospectively at one year and at the latest follow-up (mean follow-up = 4.7yrs. Range = 4 to 7 years). Biopsies of their cartilage repair site were stained with Haema-toxylin and Eosin and some with Safranin O and the neo-cartilage was graded as hyaline-like (n=32), mixed fibro-hyaline (n=19) and fibro-cartilagenous tissue (n=35). Macroscopic grading of the repair tissue using the international cartilage repair society grading system (ICRS) was available for fifty-six patients in this study cohort. Statistical analyses were performed to investigate the significance of histology and ICRS grading on MCRS at 1 year and at the latest follow-up.

Results: The MCRS of all three histology groups were comparable at one year evaluation (p=0.34). However, their clinical scores at the latest follow-up showed a significantly superior result for those with hyaline-like repair tissue when compared to those with mixed fibro-hyaline and fibro-cartilagenous repair (p=0.05).

There was no correlation between the ICRS grading and MCRS either at one year (p=0.12) or at the latest follow-up (p=0.16). Also, the ICRS grading of the repair tissue did not correlate with its histological type (p=0.12).

Conclusion: We conclude that any form of cartilage repair gives good clinical outcome at one year. At four years and beyond, hyaline-like repair tissue produces a more favourable clinical outcome. Macroscopic evaluation using the ICRS grading system does not reflect the clinical outcome or its durability or the histological type of repair tissue.

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.

Aim: The aim of this study was to correlate the histology of cartilage repair site with long term clinical function.

Materials and methods: We have analyzed the clinical results of a cohort of patients who had collagen-covered autologous chondrocyte implantations performed since 1998. Our hypothesis was that the hyaline cartilage repair does influence the clinical outcome.

The modified Cincinnati scores (MCRS) of eighty-six patients were evaluated prospectively at one year and at the latest follow-up following ACI-C (mean follow-up= 4.7 years. Range= 4 to 7 years). All these patients underwent biopsies of their cartilage repair site performed at variable periods between six months and five years following ACI-C (mean=22.2 months). The neo-cartilage was graded as hyaline (n=32), mixed fibrohyaline (n=19), fibrocartilagenous (n=35) and fibrous (n=0).

Results: The clinical results showed that at one year, the percentage of patients with excellent and good results was 84.4, 89.5 and 74.3 respectively for those with hyaline, mixed fibro-hyaline and fibro-cartilagenous histology respectively. Their mean MCRS were 70.8, 72.4 and 66.2 respectively. This difference was not statistically significant (p=0.34).

However, their clinical scores at the latest follow-up demonstrated a significantly superior result for those with hyaline repair tissue when compared to those with mixed fibro-hyaline and fibro-cartilagenous repair tissue (p=0.05). The percentage of patients with excellent and good results for those with hyaline, mixed fibro-hyaline and fibro-cartilagenous repair was 75, 42 and 68.6 respectively. Their mean MCRS were 70.6, 56.8 and 63.9 respectively.

Conclusion: This study demonstrates that any form of cartilage repair would give good clinical outcome at one year. At four years and beyond, it appears that patients with hyaline repair tissue tend to show a more favourable clinical outcome whereas those who demonstrated mixed fibrohyaline and fibrocartilagenous repair would show less favourable clinical results.