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  1. Martin P Schwellnus
  1. University of Cape Town, South Africa

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In an animal model of an induced knee cartilage injury that is treated with microfracture, the addition of three weekly injections of intra-articular hyaluronic acid improved the repair tissue at the 3-month, but not the 6-month follow-up


Intra-articular hyaluronic acid viscosupplementation has been used in the treatment of cartilage injury possibly because of its chondroprotective and anti-inflammatory properties.

Research question/s

In an animal model of cartilage injury, does intra-articular hyaluronic acid administration following microfracture improve the quality of the repair?


Animal material Thirty-six female New Zealand White rabbits.

Experimental procedure In all the animals, full-thickness cartilage defects were created in the weight-bearing area of the medial femoral condyle and then treated with surgical microfracture. Two groups of rabbits were then studied (a 3-month and 6-month group) and then killed for analysis of the knee tissue. In each group, rabbits were randomly assigned to three subgroups: three weekly injections (Hyal3=6), five weekly injections (Hyal5=6) of hyaluronic acid or saline injections (Con=6). Repair tissue was assessed (1) grossly (using a modified component of the International Cartilage Repair Society (ICRS) Cartilage Repair Assessment scoring scale) and (2) histologically (using the modified O'Driscoll histological cartilage scoring system).

Measures of outcome Gross (ICRS scores) and histological score between groups and time (3 and 6 months).

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Main finding/s

There was a significantly greater degree of synovial inflammation and osteophyte formation in the Con group compared with the Hyal3 and Hyal5 groups (p<0.05) on examination of the entire operative knee.


In an animal model of an induced knee cartilage injury that is treated with …

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