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

Since 1987, autologous chondrocyte implantation (ACI) has been performed in Gothenburg, Sweden in more than 1600 patients. Out of the first 442 patients operated with ACI, 153 (35%) had patella lesions and 91 (21%) had trochlea lesions. Forty two patients (9.5%) had kissing lesions of the patellofemoral joint.

The aim of the study was to evaluate the current clinical status of operated patients. Lysholm and Tegner-Wallgren self-assessment questionnaires were used. The patients were requested to compare their current status to previous states and to report whether they would do the operation again. Concomitant realignment procedures of the patellofemoral joint were also recorded and preoperative scores were also assessed from the medical files.

Patients were divided into groups according to the location of lesion. All the groups showed a significant improvement compared with the preoperative assessment. Over 90% of the treated patients were satisfied with the ACI and would have undergone the procedure again.

It seems that correcting the coexisting background factors with realignment, stabilizing or unloading procedures is improving the results over time. Despite the initial controversy about the results and indication for ACI in patellofemoral lesions, it is clear that ACI provides a satisfactory result even for the difficult cases with concomitant patellar instability. Our study reveals preservation of the good results and of high level of patients’ activities, even 10 to 20 years after the implantation.

Autologous chondrocytes transplantation (ACT) was first used in humans in 1987 and is based on a surgical technique where cells are injected under a periosteal flap. Due to the sometimes tricky surgical isolation and suture of the periosteum and complications with hypertrophy of periosteal tissue (5 – 10% of the cases) that in some cases requires a second arthroscopic trimming ‘easier’ transplantation techniques based on cells cultured on scaffolds and membranes have been suggested. However, the standard ACT technique creates a unique in vivo bioreactor where chondrocytes and periosteum form a unique local environment. If live periosteum and chondrocytes are transplanted to a defect in the rabbit patellae a cartilage repair tissue is formed in contrast to treatment with ‘dead’ periosteum and live chondrocytes were no repair tissue is demonstrated. The unique environment formed by the periosteum and chondrocytes might be responsible for the unique in vivo induction of early embryological development patterns seen in limb formation in the foetus: We have found that the transplanted chondrocytes are expressing early developmental genes e.g Sox 9 and wnt14 and fibroblast growth factor 3 receptors (FGFR3), a marker of chondrocytes progenitor cells. Furthermore, we have found that the articular chondrocytes are able to demonstrate a phenotypic expressivity with an additional ability of bone and adipose tissue formation. Changes to the transplantation procedure must address these unique features of the ACT technology in order to maintain the long term clinical outcome.