Effect of Rush pins on the distal femoral growth plate of young dogs.

Rush pins were placed in the distal portion of the left femur in 15 young (4 months old) mongrel dogs. Microscopic evaluation of the growth plate showed closure beginning 1 month after the pins were implanted and complete closure occurring a month earlier than in the control (right) femur. The left femurs had a mean decrease in length of 22 mm compared with the length of the control femurs at the time of growth plate closure. When the Rush pins were removed 1 month after implantation, the growth plate regained normal microscopic appearance and difference in femur lengths (left vs right) did not occur. Tibial length did not change relative to femur length. Recommendations are made about the use of Rush pins in young dogs.