FIGURE 2.

Study design of in vivo sheep lumbar spine model. Schematics and intraoperative images depicting the annulus fibrosus (AF) defects created in conjunction with nucleus pulposus removal. Intraoperative images are oriented with the cranial side of the sheep to the left, caudal to the right, ventral on the bottom, and dorsal on the top. The lumbar spine was visualized through a lateral retroperitoneal surgical approach and the intervertebral discs) were exposed (A), and those receiving the discectomy injury were subjected to a 16 mm AF annulotomy (B), two 8 mm AF annulotomies in a cruciate pattern (C), or a 5 mm by 3 mm box‐cut annulectomy (D)