Does Wallis implant reduce adjacent segment degeneration above lumbosacral instrumented fusion?

Abstract

Delayed complications following lumbar spine fusion may occur amongst which is adjacent segment degeneration (ASD). Although interspinous implants have been successfully used in spinal stenosis to authors' knowledge such implants have not been previously used to reduce ASD in instrumented lumbar fusion. This prospective controlled study was designed to investigate if the implantation of an interspinous implant cephalad to short lumbar and lumbosacral instrumented fusion could eliminate the incidence of ASD and subsequently the related reoperation rate. Groups W and C enrolled initially each 25 consecutive selected patients. Group W included patients, who received the Wallis interspinous implant in the unfused vertebral segment cephalad to instrumentation and the group C selected age-, diagnosis-, level-, and instrumentationmatched to W group patients without interspinous implant (controls). The inclusion criterion for Wallis implantation was UCLA arthritic grade \II, while the exclusion criteria were previous lumbar surgery, severe osteoporosis or degeneration[UCLA grade II in the adjacent two segments cephalad to instrumentation. All patients suffered from symptomatic spinal stenosis and underwent decompression and 2-4 levels stabilization with rigid pedicle screw fixation and posterolateral fusion by a single surgeon. Lumbar lordosis, disc height (DH), segmental range of motion (ROM), and percent olisthesis in the adjacent two cephalad to instrumentation segments were measured preoperatively, and postoperatively until the final evaluation. VAS, SF-36, and Oswestry Disability Index (ODI) were used. One patient of group W developed pseudarthrosis: two patients of group C deep infection and one patient of group C ASD in the segment below instrumentation and were excluded from the final evaluation. Thus, 24 patients of group W and 21 in group C aged 65? 13 and 64? 11 years, respectively were included in the final analysis. The follow-up averaged 60 ± 6 months. The instrumented levels averaged 2.5 ? 1 vertebra for both groups. All 45 spines showed radiological fusion 8-12 months postoperatively. Lumbar lordosis did not change postoperatively. Postoperatively at the first cephalad adjacent segment: DH increased in the group W (P = 0.042); ROM significantly increased only in group C (ANOVA, P \ 0.02); olisthesis decreased both in flexion (P = 0.0024) and extension (P = 0.012) in group W. The degeneration or deterioration of already existed ASD in the two cephalad segments was shown in 1 (4.1%) and 6 (28.6%) spines in W and C groups, respectively. Physical function (SF-36) and ODI improved postoperatively (P \ 0.001), but in favour of the patients of group W (P \ 0.05) at the final evaluation. Symptomatic ASD required surgical intervention was in 3 (14%) patients of group C and none in group W. ASD remains a significant problem and accounts for a big portion of revision surgery following instrumented lumbar fusion. In this series, the Wallis interspinous implant changed the natural history of ASD and saved th...

Biomechanical evaluation of posterior lumbar dynamic stabilization: an in vitro comparison between Universal Clamp and Wallis systems

“…Results of the current study confirm its effect on motion, and extension was the most affected. A study by Korovessis et al found that the Wallis implant could change the natural history of disc degeneration, with significant reduction of clinical and radiological incidence of ASD at 5-year follow-up [26]. The procedure to implant the Wallis is safe and associated with low morbidity, but requires the resection of the supraspinous and interspinous ligaments [13].…”

Can posterior dynamic stabilization reduce the risk of adjacent segment deterioration?

“…inclusion criteria (2,3,6,(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(26)(27)(28)(29)(30)33,34,36,37,(41)(42)(43)(45)(46)(47) (Figure 1). For the possible duplicate studies (31&40,14&23,13&15), only the data from the trial with the longest follow-up were used for estimating the incidence of ASD.…”

“…Among the eight articles that used PDS devices as adjuncts to fusion, PDS were implanted adjacent to fusion in four articles (12,22,27,33), as a component part of hybrid fusion in three (20,21,28), and both in one (41) ( Table III). Three trials compared the incidence of ASDeg/ASDis between the sole fusion and fusion plus adjacent PDS (12,22,33).…”

“…Three trials compared the incidence of ASDeg/ASDis between the sole fusion and fusion plus adjacent PDS (12,22,33).…”

Experience with the second-generation wallis interspinous dynamic stabilization device implanted in degenerative lumbar disease: a case series of 50 patients

“…The intention is to alter the load bearing pattern of the motion segment, as well as to control any abnormal motion at the segment. The hypothesis behind dynamic stabilization is that control of abnormal motions and more physiological load transmission would relieve pain, and prevent adjacent segment degeneration because it permits a certain degree of motion in the fixed segment (7).…”