Intervertebral Disk Disease

The intervertebral disk is located between two adjacent vertebrae (spinal bones) and acts as a "shock absorber" to handle forces along the spine. The disk has two parts, each of which work differently. The center portion, called the nucleus pulposus (NP), has a high water concentration and is positioned to help absorb the forces along the spinal column. The outer portion, the annulus fibrosis (AF) of the disk, acts more like a ligament. When forces impact the intervertebral disk the nucleus pulposus spreads and transmits forces outwards to the annulus fibrosus, which also spreads. While flexible, the annulus fibrosus is more rigid and maintains disk structure. When the forces along the intervertebral disk cease to exist, the elasticity of the annulus fibrosus allows the disk to return to its normal shape. Below is a schematic diagram showing the impact of these mechanical changes to a healthy disk.

Minimally Invasive Intervertebral Disk Surgery

Surgery of the lower spine typically requires significant muscle dissection to allow enough retraction of the muscles to access the area of concern. We've worked on approaches that decrease the size of the surgical approach. Depending on the size of the patient, incisions can often be minimized to 2 to 5 cm when they would otherwise be 5 to 12 cm long. We perform this procedure using a different soft tissue approach that requires less muscle dissection and tissue retraction. The theoretical benefit of minimally invasive surgery is primarily a decreased tissue injury resulting in faster healing and postoperative pain. Indeed, we have observed that those patients with spinal disease in which we can use a minimally invasive approach appear to recover more quickly and often leave the hospital earlier than those that undergo more extensive surgery.

Not all cases are good candidates for a minimally invasive approach. Dogs that require a multiple level surgery and very large or heavy dogs tend to be less optimal candidates. The suitability of the minimally invasive approach also depends upon the location of the problem in the spine. Disease in the higher thoracic spine and lower lumbar spine are less amenable to a minimal approach, but we are hopeful we can improve the technique for these areas.