K. Donald Shelbourne, Tinker Gray and Marc Haro

The incidence of re-injury to either knee following an ACL reconstruction has not been thoroughly studied. The authors hypothesised that women would have a higher incidence of ACL injury in the contralateral knee following surgery that men would. However they did not think that there would be a difference in re-injury rate in the reconstructed knee.

Over a 5 year period, 1820 ACL recon patients were monitored for injuries. Any resulting injuries were recorded, including age, sex and activity level post surgery.

The entire 5 year period was completed in 1415 patients. Seventy-five of these patients had an injury to the contralateral knee, and 61 patients suffered an injury to the reconstructed knee. Women suffered more injuries (7.8%) to the contralateral normal knee than men (3.7%; P < .001) but not more injuries to the reconstructed knee. Out of the patients under the age of 18 17% suffered a subsequent injury, compared to 7% in the 18-25 age group and only 4% in over 25’s. Returning to sport prior to 6 months following surgery resulted in no increase in injury rate.

The study concluded that women are more likely to injure the acl in the contralateral knee following ACL surgery. Younger people are also more likely to suffer any knee injury on either side, as are those with a higher activity level. Returning to full activities before 6 months made no impact on injury occurrence.

American Journal of Sports Medicine, February 2009, 37:246-251