The English jockey William Buick, a source with knowledge of the situation said, has been diagnosed with a fractured T-12 vertabrae after hitting the Arlington turf course Saturday when his mount, Permian, broke down at the wire in the Secretariat Stakes. The T-12 vertabrae is situated at the lower part of the spine, and Buick had reportedly been complaining of lower back pain. Buick has full range of motion in his extremities, and the injury won't require surgery to heal, the source said. Buick will be kept at Northwest Community Hospital overnight for evaluation and obviously will be out of action for some time.