Autologous chondrocyte implantation recommended for treating large knee lesions

Leela C. Biant

GLASGOW — Autologous chondrocyte implantation outperformed mosaicplasty at 10 years follow-up for the treatment of symptomatic articular cartilage defects of the knee in younger patients, in a prospective, randomized comparison study conducted in the United Kingdom.

Leela C. Biant, FRCSEd (Tr & Orth), MS, consultant trauma and orthopedic surgeon at the Royal Infirmary of Edinburgh, presented the results at the 2010 Meeting of the Combined Orthopaedics Associations, here.

“Autologous chondrocyte implantation was significantly better,” Biant said. “We would not recommend mosaicplasty for large lesions or for salvage after other surgery. It is useful to remember that even failures may not be failures in this group of patients if we can delay arthroplasty in the younger patient.”

Biant and colleagues included 100 consecutive patients in their study with articular cartilage lesions that had been symptomatic for an average of 7.2 years. Patients ranged in age from 16 to 49 years and the average size of the defects following debridement was 4.66 cm².

“They were not only large defects, but they were chronic,” Biant said. All but six patients had undergone previous surgery for the defect, excluding diagnostic arthroscopy and debridement, ranging from microfracture to carbon fiber implantation. The etiology of the initial defect was mainly trauma.

Patients were randomized at arthroscopy if the lesion was suitable to undergo either of the two procedures: 58 patients were treated with autologous chondrocyte implantation (ACI) and 42 with mosaicplasty, according to Biant.

Surgical techniques

Biant described the mosaicplasty technique as it was performed for this study: A parapatellar arthrotomy was performed, using 4.5-mm plugs in most cases. Care was taken not to recess the plugs or leave them proud. The knee was cycled at the end of the procedure to check the stability of the plugs, and drains were used during wound closure.

Autologous chondrocyte implantation involved a full-thickness biopsy, weighing about 200 mg or 1 cm in length, which was taken from the margin of the femoral trochlea. Cells from the biopsy were cultured in a laboratory and were reimplanted about 3 to 5 weeks later via a parapatellar arthrotomy. Care was taken at this stage to fully debride the lesion. Either a tibial periosteum or a porcine collagen patch was sutured over the defect, and sutures were reinforced with fibrin glue. The cells in suspension were then injected behind the membrane, and no drains were used during wound closure, according to Biant.

Rehabilitation was identical between the two groups, Biant said. The knee was splinted in extension, and the leg was elevated for 12 hours. Full weight-bearing was allowed at 24 hours with the knee still in extension. Splints were removed at 10 days, and early swimming, cycling and jogging activities were encouraged, but no twisting sports were allowed for 6 months and no contact sports for 1 year.

Failures, functional outcomes

Biant reported failures in 23 of 42 mosaicplasty patients and 10 of 58 ACI patients. “We defined failure as a clinically poor result with arthroscopic evidence of graft failure or revision surgery of any kind.”

Modified Cincinnati functional scores among the two groups were as follows: 28 ACI patients had excellent scores, compared to four mosaicplasty patients; seven ACI patients and five mosaicplasty patients had good scores; six ACI patients and four mosaicplasty patients had fair scores; and two patients from each group had poor scores. Biant noted that similar results were seen when using the Modified Cincinnati and Stanmore Bentley functional rating systems.

“In conclusion, this is actually the largest long-term study of either method, and it is the longest comparative study,” Biant said. “This was surgery for chronic, large lesions which may not be the sportsman come straight off the pitch. So this is a very difficult-to-treat group in whom the alternative really is arthroplasty.” – by Thomas M. Springer

Reference:

• Biant L, et al. Autologous chondrocyte implantation versus mosaicplasty for symptomatic articular cartilage defects in the young adult knee: 10-year results of a prospective randomized comparison study. Presented at the 2010 Meeting of the Combined Orthopaedic Associations. Sept. 13-17, 2010. Glasgow.

• Leela C. Biant, FRCSEd (Tr & Orth), MS, can be reached at The University of Edinburgh, The Royal Infirmary of Edinburgh, Little France Crescent, Old Dalkeith Road, Edinburgh EH16 4SA; e-mail: lcbiant@luht.scot.nhs. She has no direct financial interest in any products or companies mentioned in this article.

It is a interesting paper; previous works have been done by George Bentley’s group comparing ACI to mosaicplasty, showing that ACI is probably superior. Today they have presented longer term results still showing the same trend.

I think that this is a challenging group of patients to treat and these are large lesions. Overall, one might expect that a proportion of them might be in a more arthritic group rather than isolated defects, and so one might expect worse results. I think that multiple mosaicplasty plugs to treat large lesions may cause a problem at the donor site but also because the quality of repair will not be as good as you will find with smaller defects.

I think the lesson learned here is that mosaicplasty probably doesn’t have a role in the large defect, and we’ll wait to see the results of ACI for treating this type of defect in larger series. Very interesting and some important messages, but more data is required.

– Andrew Price, PhD, FRCS(Orth), MBBChir
Combined Orthopaedics Associations Session Moderator

Andrew Price is on the speaker’s bureau and is a paid consultant or employee of Biomet. He has received research or institutional support from Biomet, Smith & Nephew, Wright Medical Technology and Zimmer.

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