Chondral defect

Illustration to show that a chondral defect is a discrete bit of damage, rather than diffuse arthritic wear and tear.

What is the cause of a chondral defect?

A chondral defect may be caused by a sharp injury, a metabolic or genetic disorder, or poor local blood supply.

Where the rest of the cartilage is healthy the isolated crater can be assumed to have been caused by an injury, where the joint surface and a bit of underlying bone has been knocked off. The person perhaps lands with force onto the bent knee, or there is a direct blow to the knee, knocking off a piece of articular cartilage. The chondral defect is the crater, while the bit that breaks off may carry on living freely in the joint as a 'loose body'.

Other non-traumatic conditions may create a similar crater, but the margins may be less discrete.

• Quote from peer-reviewed paper:

  Such defects "...can occur as a result of mechanical factors (i.e. trauma or overuse leading to repetitive micro trauma) or biological factors (i.e. osteochondritis dissecans or osteonecrosis)"

  Citation: Howell M, Liao Q, Gee CW. Surgical Management of Osteochondral Defects of the Knee: An Educational Review. Curr Rev Musculoskelet Med. 2021 Feb;14(1):60-66. doi: 10.1007/s12178-020-09685-1. Epub 2021 Feb 15. PMID: 33587261; PMCID: PMC7930143.

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Is a chondral defect the same as an osteochondral defect?

In correct 'med-speak' a chondral defect involves damage to the cartilage layer only, while in an 'osteochondral defect' the underlying bone is also damaged or even chipped off.

The terms are, however, used a bit loosely, but the implication is that the walls of the defect are crater-like, and there may be a loose bit floating in the joint space.

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How are chondral defects of the knee managed?

Smaller defects may be managed with arthroscopic debridement, to flatten down the sharp edges and prevent further damage. A radiofrequency wand can also be used for the same purpose.

A small awl may be used to poke through to the underlying bone to allow bleeding and migration of stem cells into the defect (microfracture) to encourage healing.

If the crater is large, and the cartilage around the edges healthy, then the surgeon may try to 'patch' fill the crater with healthy cartilage, in a 'cartilage repair' procedure such as in the procedure of mosaicplasty.

• Quote from peer-reviewed paper:

  "...treatment of chondral knee injuries remains a challenge for the orthopedic surgeon, mainly owing to the characteristics of the cartilage tissue, which promote low potential for regeneration...."

  Citation: da Cunha Cavalcanti FM, Doca D, Cohen M, Ferretti M. UPDATING ON DIAGNOSIS AND TREATMENT OF CHONDRAL LESION OF THE KNEE. Rev Bras Ortop. 2015 Nov 16;47(1):12-20. doi: 10.1016/S2255-4971(15)30339-6. PMID: 27027078; PMCID: PMC4799341.

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