SONOGRAPHIC BRIGHTNESS OF THE FLEXOR TENDONS AND LIGAMENTS IN THE METACARPAL REGION OF HORSES

Sonographic observations were made of the image mean gray scale (MGS) of the flexor tendons and ligaments in the left and right metacarpal r egions of each of 10 clinically normal horses. In images made in the d orsal and sagittal planes, the MGS was measured at multiple sites in t he superficial digital flexor tendon (SDFT), deep digital flexor tendo n (DDFT), accessory ligament (AL), and suspensory ligament (SL), and a t single sites in the medial and lateral limbs of the SL, and the palm ar ligament. Relative sonographic brightness of each tendon and ligame nt was calculated by dividing the value of its MGS by the mean value f or the MGS of images of 3 soft tissue equivalent phantoms. When a mult ivariate repeated-measures of ANOVA of the relative brightness values was statistically significant (P less than or equal to 0.05), Tukey's method of multiple comparisons was used to determine which values were significantly different from each other. In the dorsal plane, the st was significantly brighter than the DDFT, SDFT, and AL; relative brigh tnesses of the DDFT and SDFT were similar, as were those of the SDFT a nd AL. In the sagittal plane, the SL again was the significantly brigh test structure, followed by the AL, and similar brightnesses of the DD FT and SDFT, In dorsal images made 25 cm distal to the accessory carpa l bone, relative brightnesses of the SDFT, DDFT, and the medial and la teral limbs of the SL were similar. In images made 30 cm distal to the accessory carpal bone, relative brightness of the palmar ligament was significantly (P < 0.05) less than that of the SDFT and DDFT in the d orsal plane, but not in the sagittal plane, where it was significantly greater. Relative brightness values represented a unique sonographic characteristic of each structure and, in the future, may provide furth er insights into tendon and ligament structure and function.