47. The effect of surgical decompression on spine and lower extremity range of motion during gait in patients with cervical spondylotic myelopathy

Abstract

BACKGROUND CONTEXT Cervical spondylotic myelopathy (CSM) is a neurologic condition resulting from spinal cord compression due to degenerative narrowing of the spinal canal. It is the most common cause of spinal cord dysfunction in patients older than 50. Symptoms of CSM may include numbness or weakness in the extremities, loss of fine motor dexterity, and difficulty with balance and gait. The natural history is typically one of progressive decline in neurologic function, so surgery to decompress the spinal cord is generally indicated to prevent progression in symptomatic patients. Despite the prevalence of this condition, relatively little quantitative kinematic information is available on the effect of surgical intervention on the gait of patients with CSM. PURPOSE To evaluate for changes in the spine and lower extremity range of motion (RoM) during gait in patients with CSM before and after surgical intervention. STUDY DESIGN/SETTING Non-randomized, prospective, concurrent cohort study. PATIENT SAMPLE Thirty-eight patients with symptomatic CSM. OUTCOME MEASURES Lower extremity and spine range of motion (RoM), spatiotemporal parameters, and pain level. METHODS Clinical gait analysis was performed one week before surgery (Pre) and three months after surgery (Post). Fifty reflective markers (9.5 mm diameter) attached to the patients; bodies were utilized to collect full body three-dimensional kinematics using 10 cameras (VICON) at a sampling rate of 100 Hz. Each patient performed a series of over-ground gait trials at a comfortable, self-selected speed. Neck and mid-back visual analog scale (VAS), Oswestry Disability Index (ODI), and Neck Disability Index (NDI) scores were also collected at both time points. Repeated measurements ANOVA was used to analyze data. RESULTS When comparing preoperative to postoperative gait parameters, significant increases in walking cadence (98.28 vs 103.37 steps/minutes, p=0.004), stride length (1.02 vs 1.07 m, p=0.018), and walking speed (0.86 vs 0.94 m/s, p=0.001) were observed. The amount of time spent in double support decreased after surgery (0.37 vs 0.32 s, p=0.032). The only significant difference in spine and lower extremity joint RoM measures was a decline in coronal RoM of both the knees and ankles postoperatively. VAS neck and mid-back as well as ODI improved significantly postoperatively, while the reduction in NDI did not attain statistical significance. CONCLUSIONS Despite conventional teaching that the goal of surgical intervention for CSM is to halt symptomatic progression, the data presented here demonstrate that significant improvements in gait are frequently observed after surgical management of CSM. Postoperative patients walk more quickly as a result of increased stride length and cadence. Furthermore, they lift their knees and dorsiflex/plantarflex their ankles less, consistent with a more efficient gait pattern. While surgeons should remain conservative with respect to how they counsel patients and set expectations preoperatively, cautious optimism regarding improvements in gait may be warranted in the setting of surgery for CSM. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.