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 chondrocyte transplantation is a two-stage procedure for treating full-thickness chondral and osteochondral joint lesions. It has been used in more than 1200 patients in Sweden and 8000 outside of Sweden.

No serious general complications have been seen, no deep infections, no deep thrombosis.

Relevant serious complications are graft delaminations, especially in partial or total loss of attatchment. These can be a result of inadequate surgical technique, too aggressive rehabilitation or too early return to competitive highimpact sports. They often occur 6–12 months postop. Marginal delaminations can be handled by debridement and microfracture. Partial and total graft delaminations need retransplantation. This can be performed with good result. More common complications are periosteal delamination and hypertrophy of the periosteal flap causing catching, pain and swelling. If symptoms does not disappear with a change in rehabilitation an arthroscopic debridement is necessary.

Arthrofibrosis with limited R.O.M. is treated with intensified physical therapy. If that fails arthroscopic debridement is needed. Other relevant complications like infection and thrombosis could usually be prevented.

Osteoarthritis is the end stage of a gradual process of degradation of the cartilage and secondary responses in other tissues within a joint after many years of use. It is common in the knee joints in elderly. The surgical treatments for OA are often symptomatic, such as arthroplasty and HTO. Traumas to the knee, especially in combination with other injuries such as ACL rupture or meniscal tears, can lead to a speedy process and premature OA. The osteoarthritic patient often experiences a gradual on set of symptoms such as pain and swelling on weight bearing, catching and locking and in late stage nightly pains, leading to a very limited lifestyle. If it is possible to treat the OA at an early stage and thus hindering the destruction of the joint, much is won for the patient.

Autologous chondrocyte transplantation (ACT) is a treatment for focal chondral and osteochondral lesions in the knee joint. The technique has also been used on patients with early stages of OA in knee, including multiple lesions, kissing lesions, lesions in combination with malalignment, instability and total mensicectomy. When treating these patients it is important to not only focus on the cartilage lesions but also on other pathology. A high tibial osteotomy should be considered, especially if there is a malalignment, but also as an unloading procedure if the lesion is large or if there are bipolar kissing lesions. If the patient has had total or subtotal meniscectomy meniscal allograft transplantation may be indicated. Ligamentous instability from a ruptured ACL for example must also be treated. All these procedures can be done prior to or after the ACT, but mostly concomitant with the ACT. As the patients have often been symptomatic for a long time and the greater surgical trauma with a concomitant procedure, it is harder to regain knee function after the surgery. Close contact between the patient, the doctor and the physical therapist is imperative, so measures can be taken if the patient does not progress accordingly.

Young patients with early OA are hard cases. These patients often have a high demand on knee function and have had a high level of activity but are disabled by their symptoms. When treating these patients with ACT it is important to assess and treat all pathology that may jeopardize a good outcome.

Lesions to articular cartilage have a poor capability of regeneration and by mechanical wear and enzymatic digestion they may progress to osteoarthritis. In Sweden more than 900 patients with chondral or osteochondral lesions have been treated with autologous chondrocyte transplantation (ACT) since 1987. Cartilage is harvested arthroscopically and the chondrocytes are isolated. After two weeks of culturing the chondrocytes are deposited in the cartilage lesion in a cell suspension. The chondrocytes start to produce matrix and gradually form new hyaline cartilage able to withstand the forces of the knee.

Lesions to the femoral condyles have shown the most promising results when treated with ACT (90% Good/Excellent, n=57), osteochonditis dissecans showed 84% Good/Excellent results (n=32), multiple knee joint lesions 75% Good/Excellent (n=53) and femoral condyle lesions with anterior cruciate ligament reconstruction 74% Good/Excellent (n=−27) at a long term follow up (2–11 years). The outcome after patella lesions treated with ACT were initially not as good (2 of 7 patients were graded Good or Excellent at a mean follow-up of 36 months) but better understanding of the nature of patellar lesions and development of the surgical technique have improved the result (65% Good or Excellent, n=32). Patients treated with ACT for cartilage lesion to the femoral trochlea showed Good/Excellent results in 58% (n=12).

At a second look arthroscopy biopsies were taken in 37 patients. In 80% of the biopsies the repair tissue was classified as hyaline like cartilage. Immunohistochemical analysis of collagen II, aggrecan and comp showed ++ to +++ for the hyaline like repair tissue compared to +++ for normal cartilage. There were also a strong correlation (0.73) between hyaline like repair and Good/ Excellent results.

Other areas have been transplanted as well such as the tibial plateau, the talus and the head of the humerus, but due to the small numbers of patients and short follow-up ACT to these areas is not yet recommended.

The clinical outcome after treating chondral and osteochondral lesions in the knee is good at a long term follow-up and the repair tissue is histological similar to normal articular cartilage.