Knutsen ACI vs microfracture

Autologous chondrocyte implantation compared with microfracture in the knee. A randomized trial

Knutsen G, Engebretsen L, Ludvigsen TC, et al. The Journal of bone and joint surgery. American volume 2004 · PMID 14996869 · doi:10.2106/00004623-200403000-00001

Question

Does ACI give better outcomes than microfracture for isolated femoral condyle cartilage defects?

Design

Multicentre randomised trial in Norway.

Patients

Adults with a single symptomatic full-thickness cartilage defect of the femoral condyle and a stable knee.

Intervention

Autologous chondrocyte implantation with periosteal cover

Comparison

Arthroscopic microfracture

Primary outcome

Lysholm, SF-36 and ICRS scores with second-look arthroscopy and biopsy at 2 years

Key result

Both groups improved at 2 years with no clinically important difference in clinical outcome; microfracture showed better SF-36 physical component improvement, and histology did not show clear superiority of ACI.

Limitations

Modest sample size, first-generation periosteal ACI and short follow-up; longer-term reports also found no significant difference.

Impact on practice

Tempered enthusiasm for routine ACI for smaller defects and supported microfracture as a reasonable first-line marrow stimulation option, with ACI reserved for larger or failed lesions.