Endoscopic-assisted lumbosacral foraminotomy in the dog.

OBJECTIVE To determine if endoscopic-assisted foraminotomy significantly increased the area of the L7-S1 intervertebral foramen and if, over 12 weeks, stenosis would occur. STUDY DESIGN Prospective, experimental study. ANIMAL POPULATION Six clinically normal, 22-29 kg, adult dogs. METHODS Using endoscopic assistance, unilateral L7-S1 foraminotomy was performed. Computed tomography of L7-S1 was performed preoperatively, immediately postoperatively, and at 12 weeks. Parasagittal foramen area (PFA) measurements were obtained at the entry, middle, and exit zones of the treated and control foramen for each period. Objective and subjective data were compared among dogs by time period and treatment status. RESULTS Endoscopic-assisted foraminotomy resulted in a significant increase in the mean PFA of the entry and middle zones immediately postoperatively. The exit zone was not significantly larger at any time. The foramen remained significantly larger at 12 weeks only in the middle zone; however, some decrease in the surgically created foramen enlargement occurred at all 3 levels. The procedure was well tolerated but dogs did have transient, mild delay of functional return postoperatively. CONCLUSIONS Endoscopic-assisted foraminotomy in dogs can be performed for certain foraminal regions, allowing enhanced visibility of the spinal canal. The foramen can be surgically enlarged at the entry and middle zones using this technique; however, some reduction of the foraminal enlargement occurs by 12 weeks. The clinical implications of this reduction cannot be determined from this study. CLINICAL RELEVANCE Endoscopic-assisted foraminotomy could be used to improve intraoperative visualization in dogs with foraminal stenosis as a component of degenerative lumbosacral stenosis.