First-generation versus second-generation autologous chondrocyte implantation for treatment of cartilage defects of the knee: a matched-pair analysis on long-term clinical outcome

Purpose

Since the introduction of autologous chondrocyte implantation (ACI) for the treatment of cartilage defects, the initial technique has undergone several modifications. Whereas an autologous periosteum flap was used for defect coverage in first generation ACI, a standardized collagen membrane was utilized in second generation ACI. To date, however, no study has proven the superiority of this modification in terms of long-term clinical outcome. The purpose of this matched-pair analysis was therefore to compare the clinical long-term outcome of first and second generation ACI with a minimum follow-up of ten years.

Methods

A total of 23 patients treated with second generation ACI for isolated cartilage defects of the knee were evaluated after a minimum follow-up of ten years using Lysholm and IKDC scores. The results of these patients were compared to those of 23 matched patients treated with first generation ACI. Pair wise matching was performed by defect location, patient age, and defect size.

Results

While all patient characteristics such as age (31.7 years SD 6.9 vs. 31.4 years SD 7.8), defect size (5.1 cm² SD 2.3 vs. 4.9 cm² SD 1.5), and follow-up time (10.7 months SD 1.0 vs. 10.5 months SD 0.6) were distributed homogenously in both treatment groups, significant better Lysholm (82.7 SD 9.9 versus 75.6 SD 11.8; p?=?0.031) and IKDC scores (76.4 SD 12.8 versus 68.0 SD 12.0, p?=?0.023) were found in the group of patients treated with second generation ACI compared to those treated with first generation ACI. In both groups, four patients (17.4 %) received surgical reintervention during follow-up.

Conclusions

The use of a collagen membrane in combination with autologous chondrocytes (second generation ACI) leads to superior clinical long-term outcome compared to first generation ACI. Based on these results, second generation ACI should be preferred over first generation ACI.