[Mid-term follow-up efficacy of interspinous dynamic stabilization system for lumbar degenerative diseases]

To explore mid-term clinical efficacy and effect on adjacent segment degeneration of Wallis and Coflex interspinous implants for lumbar degenerative diseases.

From January 2011 to January 2013, 55 patients with L4, 5 degenerative lumbar spine diseases treated with interspinous devices were retrospectively analyzed, including 31 males and 24 females aged from 25 to 67 years old with an average of 43.3 years old; 21 patients were lumbar spinal stenosis and 34 patients were lumbar disc herniation. All patients were divided into Wallis group (33 cases) and Coflex group (22 cases) according to the interspinous fixation system. Visual analogue scale(VAS) was used to evaluate low back pain and lower limb pain, Japanese Orthopedic Association(JOA) score and Oswestry Disability Index(ODI) score were used to evaluate lumbar function. Surgical segment and adjacent segments, range of motion(ROM), disc height and the Pfirrmann grade of upper the adjacent segments were compared before and after operation.

Fifty-five patients were followed up from 48 to 72 months with an average of 60.4 months. VAS score of low back pain and lower limb pain, JOA and ODI score of lumbar at 48 months after operation were improved than before operation between two groups(P<0.01), but there was no statistical difference for group comparisons(P>0.05). ROM, disc height of surgical segments were significantly lower than those before operation between two groups (P<0.05), while ROM of the upper and lower adjacent segments and disc height did not change significantly (P>0.05). There was no significant difference in ROM and disc height for group comparisons(P>0.05). There was no change in Pfirrmann grade of the upper adjacent segment degeneration between two groups(P>0.05). Four patients with primary lumbar disc herniation had a recurrence of 1 to 3 years after operation, including 3 in Wallis group and 1 in Coflex group, with an average age of 35.2 years old.

Wallis and Coflex interspinous implants have the similar mid-term efficacy for the treatment of lumbar degenerative diseases, and could delay adjacent segment degeneration, but could not prevent recurrence of disc herniation.