Objective To evaluate preliminary effect of In-Space percataneous interspinous spacer in the treatment of lumbar instability.Methods Data of 18 patients who had undergone interspinous spacer implant for lumbar instability from May 2009 to June 2011 were retrospectively analyzed.There were 10 males and 8 female,aged from 39 to 58 years.All patients suffered from varying degrees of lower back pain induced by lumbar hyperextension,as well as radiating and segmental pain of unilateral lower limb.The visual analogue scale (VAS) and Oswestry disability index (ODI) were used to evaluate clinical outcomes.The pre-and postoperative interspinous distance,trailing edge height of intervertebral space,foraminal width,foraminal height,segmental lordotic angle and lumbar range of motion were tested and compared.Results All patients were followed up for 18 to 36 months.The VAS score improved from preoperative 7.9±2.1 to 3.1±1.3 at 6 months postoperatively and 1.5±0.8 at final follow-up.The ODI improved from preoperative 82.1％±13.1％ to 54.7％±14.8％ at 6 months postoperatively and 10.1％±2.5％ at final follow-up.The postoperative interspinous distance,trailing edge height of intervertebral space,foraminal height,foraminal width,segmental lordotic angle and lumbar range of motion were 9.29±1.43 mm,11.28±0.85 mm,21.27±1.01 mm,10.83±0.73 mm,7.62°±0.74° and 6.34°±0.81°,respectively.Wound healed smoothly in all patients,and there were no complications such as spinous process fracture,spinal cord injury,cerebrospinal fluid leakage,device displacement and device dislocation.Conclusion It is easy and safe to use In-Space percataneousinterspinous spacer in the treatment of lumbar instability,and the preliminary effect is satisfactory.

Objective To investigate the difference of short-term clinical efficacy between decompressive laminectomy into In-Space and simple decompressive laminectomy for treatment of lumbar spinal stenosis with vertebral instability.Methods Thirty-three patients with lumbar spinal stenosis with vertebral instability admired from May 2009 to July 2010,were divided into two groups by random number table.Group A of 16 cases was treated with laminectomy decompression and placement In-Space,group B of 17 cases was treated with laminectomy decompression.Lumbar anteroposterior,lateral and flexion-extension X-ray films,preoperatively,and the follow-up were used to measure anterior and posterior disc height,foraminal height,segmental lordotic angle at surgical level.Using Oswestry disability index (ODI) and the visual analogue scale (VAS) to evaluate the clinical efficacy.Results All patients were followed up for (13.20 ± 2.91 ) months (range 6 to 21 months).The anterior disc height after operation of group A was slightly decreased compared with the preoperative(P＞ 0.05 ),the posterior disc height at 1 day after operation and foraminal height after operation of group A were significantly increased compared with the preoperative (P＜ 0.05).The anterior and posterior disc height,foraminal height of group B at 1 day,1 month,3 months after operation were no significantly different compared with the preoperative (P ＞ 0.05 ),at 6 months after operation and the end of follow-up were significantly decreased compared with the preoperative or 1 day after operation (P ＜ 0.05 ).Activity of lumbar vertebra by preoperative 9.86° ± 1.90° decreased to the end of followup 5.60° ± 2.02°in group A,while activity of lumbar vertebra by preoperative 9.89° ± 2.00°increased to the end of follow-up 10.76° ± 3.14° in group B.At the end of follow-up,lumbar back pain VAS,ODI score [ (2.02 ± 1.98 ),( 20.18 ± 18.80) scores ] of group A were significantly lower than those of group B [ (4.15 ±2.36),(30.39 ± 16.62 ) scores ],the differences were statistically significant (P ＜ 0.05 ).No patient suffered In-Space loosening,fracture and emerge.Conclusion The operation of In-Space can maintain spinal mobility and stability as well as avoiding lumbar vertebral instability,and its short-term efficacy is satisfactory.