Summary

Gel-based ACI is an effective treatment option with a low complication rate and revision rate for repair of large focal articular cartilage defects of the knee, and results in significant improvement in functional scores when evaluated 7 to 14 years following the procedure.

Abstract

Background

Autologous chondrocyte implantation (ACI) has been established as an effective treatment option for large articular cartilage defects of the knee as it results in hyaline-rich cartilage repair and regeneration. However, conventional ACI is a complex surgical procedure with unpredictable topographic restoration of the articular surface. Gel-based ACI (GACI) enables a simpler and more effective delivery of chondrocytes with reproducible three dimensional structural restoration of the articular cartilage surface. Although GACI has been available for clinical use for almost two decades now, there is limited documentation of medium-term outcomes.

Methods

This multicentric retrospective study analysed data of patients who had undergone gel-based ACI (CARTIGROW®) for the treatment of focal articular cartilage defects of the knee between 2008 to 2014 and had a minimum 7 year follow-up after surgery. Inclusion criteria were patients aged 18 to 60 years, with isolated focal articular cartilage defects of the knee joint of ICRS grade III or IV severity, or unstable osteochondritis dissecans, and normal coronal limb alignment. The primary outcome measure was change in Lysholm Knee Scoring Scale, and Knee Outcome Sports Activity Scale (SAS). The secondary outcome measure was MRI assessment of cartilage repair using MOCART. We also assessed complications following GACI, time to resume sports following GACI, and need for revision surgery following GACI.

Results

107 patients (110 knee joints) with mean age 31.0±10.5 years fulfilled all criteria and were included in the study. The mean follow-up following GACI was 9.8 ± 1.5 years (range 7.85-13.43). 39 of the articular cartilage defects (35.4%) were ICRS grade III, 20 (18.2) were ICRS grade IV, whereas 51 (46.4%) were osteochondritis dissecans (ICRS OCD II to IV). The mean defect size was 4.5±5.8 cm2. The mean Lysholm score was preoperative 51.32±17.89 and postoperative at latest follow-up 81.23±13.21. This improvement was statistically significant (p<0.0001). Similarly, SAS score also significantly improved (p<0.0001) from mean preoperative 28.11±12.28 to mean postoperative 80.93±8.26 at latest follow-up. MOCART scores in 39 patients who had undergone a postoperative MRI at minimum 2 years follow-up ranged from 45 to 100 with a mean of 84.5+4.3. Of the 5 patients who underwent a routine relook arthroscopy at minimum one year follow-up, repair assessment was graded as normal (ICRS grade I) in 3, and nearly normal (ICRS grade II) in 2. One patient underwent a postoperative biopsy that confirmed a hyaline-rich cartilage repair. Among 30 patients who were playing sports before treatment, 56.7% (n=17) could return to the same or higher level of sports post-transplantation. The mean duration to resume sports was 8.32±1.9 months. No major intra-operative or post-operative complications were noted. 4 patients warranted revision surgery and included one arthroscopic debridement, two mosaicplasty, and one total knee replacement.

Conclusion

Gel-based ACI is an effective treatment option with a low complication rate and revision rate for repair of large focal articular cartilage defects of the knee, and results in significant improvement in functional scores (Lysholm knee score, and Knee Outcome Sports Activity Scale) when evaluated 7 to 14 years following the procedure.