title: Long-term Outcome After Monosegmental L4/5 Stabilization for Degenerative Spondylolisthesis With the Dynesys Device.
abstract: METHODS
  Retrospective analysis of prospectively collected clinical data.
  
  
  OBJECTIVE
  To assess the long-term outcome of patients with monosegmental L4/5 degenerative spondylolisthesis treated with the dynamic Dynesys device.
  
  
  BACKGROUND
  The Dynesys system has been used as a semirigid, lumbar dorsal pedicular stabilization device since 1994. Good short-term results have been reported, but little is known about the long-term outcome after treatment for degenerative spondylolisthesis at the L4/5 level.
  
  
  METHODS
  A total of 39 consecutive patients with symptomatic degenerative lumbar spondylolisthesis at the L4/5 level were treated with bilateral decompression and Dynesys instrumentation. At a mean follow-up of 7.2 years (range, 5.0-11.2 y), they underwent clinical and radiographic evaluation and quality of life assessment.
  
  
  RESULTS
  At final follow-up, back pain improved in 89% and leg pain improved in 86% of patients compared with preoperative status. Eighty-three percent of patients reported global subjective improvement. Ninety-two percent would undergo the surgery again. Eight patients (21%) required further surgery because of symptomatic adjacent segment disease (6 cases), late-onset infection (1 case), and screw breakage (1 case). In 9 cases, radiologic progression of spondylolisthesis at the operated segment was found. Seventy-four percent of operated segments showed limited flexion-extension range of <4 degrees. Adjacent segment pathology, although without clinical correlation, was diagnosed at the L5/S1 (17.9%) and L3/4 (28.2%) segments. In 4 cases, asymptomatic screw loosening was observed.
  
  
  CONCLUSIONS
  Monosegmental Dynesys instrumentation of degenerative spondylolisthesis at L4/5 shows good long-term results. The rate of secondary surgeries is comparable to other dorsal instrumentation devices. Residual range of motion in the stabilized segment is reduced, and the rate of radiologic and symptomatic adjacent segment degeneration is low. Patient satisfaction is high. Dynesys stabilization of symptomatic L4/5 degenerative spondylolisthesis is a possible alternative to other stabilization devices.
authors.affiliation: *Das Rückenzentrum, Spinal Surgery, Thun†Department of Orthopaedic Surgery, University of Bern, Inselspital‡MEM Research Center, Bern§Department of Radiology, University of Bern, Inselspital, Bern, Switzerland.
authors.forename: Sven
authors.initials: S
authors.lastname: Hoppe
authors.forename: Othmar
authors.initials: O
authors.lastname: Schwarzenbach
authors.forename: Emin
authors.initials: E
authors.lastname: Aghayev
authors.forename: Harald
authors.initials: H
authors.lastname: Bonel
authors.forename: Ulrich
authors.initials: U
authors.lastname: Berlemann
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation*; D013168:Spondylolisthesis / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome