How hard can it be – just glue some cartilage onto the bone (part IV)

It's nice to see some real orthopaedic rocket science

It’s nice to see some real orthopaedic rocket science. The picture (cc) is by Calsidyrose

It is rare to see long term follow-up studies ( > 5 years) and Bentley et al’s randomized controlled study on cartilage defects is therefore a rare bird! They randomized 1 00 consecutive patients to chondrocyte transplantation or mosaicplasty. After 10 years they were able to follow-up 94 % of all patients – a truly amazing accomplishment!

The method for chondrocyte transplantation was “simple”: harvest a few chondrocytes from the knee, grow them in a dish and the reinsert them and cover it up with a piece of tissue so that the cells don’t escape. I guess growing the cells requires a lot of expertise but apart from that no fancy gadgets were needed.


They showed that the mosaicplasty failed more than twice as often as the transplant. They also noted a sharp increase in failure rate after 2 years in the mosaicplasty group – vindicating the need for long-term follow-up. The patient scores also favored the transplanted group although only one of them, the Cincinatti score, was truly significant.

Some study issues

I think this is one of the most beautiful studies I’ve seen :

  • Good, long follow-up
  • Comparison of two relevant techniques
  • A selection of clinically relevant patients – 94 % had previously tried microfracturing and the average defect was between 200-500 mm2
  • Mean time of symptom duration was 7.2 years indicating that this works as a salvage procedure which is what I think is reasonable until this technique becomes common knowledge

It would be great to have a truly double blind study. They might have been able to blind the patients: perform a sham surgery the first time and the arthrotomy mosaicplasty the second time.

Assessment of the graft was done at one year postoperative. It would have been interesting to have xrays after ten years investigating signs of osteoarthritis and perhaps even MRI although MRI is usually harder to interpret that plain xrays.

Bentley, G., L. C. Biant, S. Vijayan, S. Macmull, J. A. Skinner, och R. W. J. Carrington. ”Minimum ten-year results of a prospective randomised study of autologous chondrocyte implantation versus mosaicplasty for symptomatic articular cartilage lesions of the knee”. Journal of Bone and Joint Surgery – British Volume 94-B, num. 4 (Mars 20, 2012): 504–509.

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