Many methods have been used to straighten crooked limbs on foals, and in the past staples placed across the “long” side’s growth plate have received somewhat mixed reviews. However, some researchers suggest that this was due to poor staple choice and resulting complications. Stephanie Caston, DVM, an equine surgeon at Iowa State University, showed attendees an updated method for making, placing, and removing transphyseal staples at the 2007 American Association of Equine Practitioners Convention, held Dec. 1-5 in Orlando, Fla.

Caston reviewed the success rates of the staple method for 63 foals over the last six years. These included 32 foals with unilateral (in one leg only) carpus valgus, or an inwardly deviated knee; 20 foals with bilateral (in both forelimbs) carpus valgus; three with carpus varus (an outwardly deviated knee); and eight with fetlock deformities.

Rather than using the traditional vitallium staples, which were developed for human use and might not be strong enough for heavier equine use, Caston and colleagues used 2.7-mm Steinmann pins to create sturdier staples. The straight pins are bent at right angles 3 cm apart to create the staples, and the ends are sharpened with a bench grinder. Smaller staples are made for fetlocks and miniature horses.

“These staples are secure, easy to make and insert, economical, they can be placed in the field, and they have a great cosmetic outcome,” Caston commented. The procedure is only used on foals with severe deformities or those that haven’t self-corrected by about two months of age.

The incision is offset a bit from the staple, which helps avoid dehiscence (reopening of the incision), and the staple is left slightly “proud” (not flush with the bone) to facilitate later removal. The surgical limb is wrapped with a padded pressure bandage for about two weeks, and the foal is stall-confined until the limb is halfway straightened (small paddock turnout is allowed after that). Once the limb is straight, the staple is removed under sedation or general anesthesia.

Caston noted that all 63 foals corrected completely in an average of 47 days, and only six had minor complications that all resolved with bandaging. One foal (a Clydesdale) had staple spreading, which was corrected with two new staples. The procedure time was fairly quick–32 minutes for bilateral staples, 19 minutes for unilateral staples, 31 minutes for staple removal, and 16 minutes for unilateral removal (all in anesthetized foals). Removal took about 10 minutes in standing foals, and 19 foals had staples removed by the referring veterinarian rather than the veterinary hospital.

“These transphyseal staples are easily made, placed, and removed with minimal equipment, and they’re economical, cosmetic, and secure, unlike what was found in previous literature,” Caston concluded.