Charles Hartjen

A multicenter, prospective, randomized trial evaluating the X STOP interspinous process decompression system for the treatment of neurogenic intermittent claudication : Two-year follow-up results

Study Design. A randomized, controlled, prospective multicenter trial comparing the outcomes of neurogenic intermittent claudication (NIC) patients treated with the interspinous process decompression system (X STOP) with patients treated nonoperatively. Objective. To determine the safety and efficacy of the X STOP interspinous implant. Summary of Background Data. Patients suffering from NIC secondary to lumbar spinal stenosis have been limited to a choice between nonoperative therapies and decompressive surgical procedures, with or without fusion. The X STOP was developed to provide an alternative therapeutic treatment. Methods. 191 patients were treated, 100 in the X STOP group and 91 in the control group. The primary outcomes measure was the Zurich Claudication Questionnaire, a patient-completed, validated instrument for NIC. Results. At every follow-up visit, X STOP patients had significantly better outcomes in each domain of the Zurich Claudication Questionnaire. At 2 years, the X STOP patients improved by 45.4% over the mean baseline Symptom Severity score compared with 7.4% in the control group; the mean improvement in the Physical Function domain was 44.3% in the X STOP group and −0.4% in the control group. In the X STOP group, 73.1% patients were satisfied with their treatment compared with 35.9% of control patients. Conclusions. The X STOP provides a conservative yet effective treatment for patients suffering from lumbar spinal stenosis. In the continuum of treatment options, the X STOP offers an attractive alternative to both conservative care and decompressive surgery.

Two-Year Evaluation of the X-STOP Interspinous Spacer in Different Primary Patient Populations With Neurogenic Intermittent Claudication Because of Lumbar Spinal Stenosis.

Study Design:Multicenter, prospective single-arm study in patients diagnosed with neurogenic intermittent claudication because of lumbar spinal stenosis. Objective:To collect data from 2 different primary patient populations, new participants meeting entry criteria [Continued Access Program (CAP)], or subjects who had been randomly assigned to nonsurgical management in the pivotal Investigational Device Exemption study and failed to respond upon study completion [Crossover Study (COS)]. Summary of Background Data:The X-STOP interspinous spacer is a minimally invasive treatment option for neurogenic intermittent claudication shown to improve pain, physical functioning, and/or overall quality of life. Methods:Fifty-five subjects were enrolled, 42 in CAP and 13 in COS. Zurich Claudication Questionnaire (ZCQ) success rates were obtained based on the number of subjects achieving a threshold level of success. Mean SF-36 domain scores were compared with baseline using repeated measures analysis of variance. Results:Eighty percent of subjects completed the study. At 2 years, 26/43 subjects (60.5%) achieved clinically significant improvement in the Symptom Severity domain, 25/43 (58.1%) achieved clinically significant improvement in the Physical Function domain, and 31/44 (70.5%) achieved clinically significant improvement in the Patient Satisfaction domain of the ZCQ. Statistically significant improvement in mean scores was obtained in all physical domains of the SF-36 (with the exception of General Health) at 24 months. Mean improvement in ZCQ and SF-36 scores was not as pronounced in the COS cohort compared with the CAP cohort. The most frequently reported device-related or treatment-related adverse event was stenosis pain reported by 3 subjects. Conclusions:Overall data are consistent with the randomized pivotal Investigational Device Exemption trial. On the basis of the COS cohort which was subject to several additional years of failed conservative treatment, overall success rates do not improve as greatly in patients with long-standing lumbar spinal stenosis symptoms.

9:26 Treatment of lumbar spinal stenosis with an interspinous spacer

Abstract Purpose of study: A newly developed spinal implant for the treatment of symptomatic lumbar spinal stenosis is being evaluated in a prospective randomized multicenter study. The implant is placed between the spinous processes of the affected level(s), and the intent is to position the stenotic segment in slight flexion, and by preventing extension, the symptoms of lumbar spinal stenosis will be relieved. The primary objective of this study is to evaluate the safety and efficacy of the implant in a clinical trial setting. Methods used: The surgical implantation of the implant is performed under local anesthesia and routinely requires 30 minutes to 1 hour of surgical time. There is negligible blood loss. The patients typically return home 3 hours after surgery. Two hundred nine patients with neurogenic claudication at the L3–L4 and/or L4–L5 levels have been enrolled in the randomized prospective study. One hundred fifteen of these patients have received the implant (X-Stop; St. Francis Medical Technologies, Concord, CA), and 94 have been treated conservatively including epidural injections. Before surgery, all patients completed an initial Zurich Claudication Questionnaire (ZCQ). The ZCQ is a self-administered survey developed to be a spinal stenosis specific outcome measure consisting of symptom severity, physical function and satisfaction scales [1] . A patient must improve in each of the three categories to be considered a success. In the current study, the ZCQ scores were available for comparison between the implant and conservative groups at 6-week, 6-month and 1-year time points. The two groups were compared statistically using Fishers exact test (p of findings: To date, 209 patients have completed the 6-week ZCQ (115 implant and 94 conservative), 176 have completed the 6-month ZCQ (91 implant and 85 conservative) and 100 have completed the 1-year questionnaire (46 implant and 54 conservative). The overall success rates for the implant group are significantly greater than those of the conservative group at each time point (Table 1) Table 1 . Success rates of the implant and conservative groups Implant success Conservative success p Value 6 weeks 66/115 (57%) 9/94 (10%) 6 months 50/91 (55%) 5/85 (6%) 1 year 32/46 (70%) 1/54 (2%) . Moreover, at 1 year the success rates for the symptom severity, physical function and satisfaction categories were 86%, 83% and 88%, respectively, for the implant group, and 11%, 11% and 28% for the conservative group. Relationship between findings and existing knowledge: The results of this study demonstrate that the implant may be effective in treating pain in patients with lumbar spinal stenosis. This series of patients demonstrates the relative safety and efficacy of a newly developed spinal implant for the treatment of symptomatic lumbar spinal stenosis. In many ways this short-term preliminary follow-up compares favorably to traditional surgical treatment as well as nonsurgical treatment in selected cases. The surgical procedure is minimally invasive, inexpensive and safe. There were no intraoperative complications. Finally, the measurement instrument has been demonstrated to be responsive and sensitive enough to measure clinically significant improvements in mild to severe cases. Overall significance of findings: These findings indicate that the implant may be an effective means of treating painful and debilitating symptoms of lumbar spinal stenosis. Disclosures: Device or drug: X-Stop, Investigational Device Exemption (IDE). Status: investigational. Conflict of interest: Scott Yerby, stockholder; James Zucherman, stockholder; Ken Hsu, stockholder.