Use of quantitative analysis of sonographic brightness for detection of early healing of tendon injury in horses

Objectives-To determine whether quantitative analysis of sonographic bright ness could be used to detect healing of an induced injury of the superficia l digital flexor tendon in horses and whether rate of healing was influence d by equine recombinant growth hormone. Animals-8 clinically normal Standardbreds. Procedures-A localized injury was created in the left and right superficial digital flexor tendons of each horse by injection of 2,000 units of collag enase. After injury, 4 horses received equine recombinant growth hormone, a possible promoter of tendon healing. Sonographic images (7.5 MHz) of the f lexor tendons and ligaments of the metacarpal region were recorded on video tape prior to injury and weekly for 7 weeks after injury. Images were digit ized, and sonographic brightness of tendons and ligaments was calculated. Results Collagenase-induced injury was sonographically similar to naturally occurring injury. After injury, sonographic brightness of the tendon decre ased; after 3 weeks, brightness progressively increased, although by 7 week s brightness had not returned to preinjury value. Equine recombinant growth hormone had no significant effect on the rate of tendon healing, as evalua ted sonographically or at necropsy. Conclusions and Clinical Relevance As healing developed, alterations in son ographic brightness of injured tendons coincided with real changes in tendo n structure. Quantitative sonographic brightness could be used to accuratel y monitor healing of equine tendon and ligament injuries and investigate th e efficacy of various treatment regimens.