Clinical Experience With the Dynesys Semirigid Fixation System for the Lumbar Spine

Surgical and Patient-Oriented Outcome in 50 Cases After an Average of 2 Years

Abstract

Study Design. 

Retrospective study on a consecutive series of patients.

Objectives. 

To examine patient-oriented outcome after Dynesys implantation.

Summary of Background Data. 

The dynamic neutralization system for the spine, Dynesys, is a nonfusion pedicle screw stabilization system, which was developed in an attempt to overcome the inherent disadvantages of rigid instrumentation and fusion. Although the system has been in clinical use for more than 5 years, no studies from disinterested research groups have reported on patient-oriented outcome after surgery with Dynesys.

Methods. 

A total of 50 consecutive patients instrumented with Dynesys over the preceding 40 months were invited to complete a postal, patient-oriented follow-up questionnaire. The data from 31 of 31 of these, with at least 2 years’ follow-up, were analyzed (mean age, 50 years; SD, 13 years; 20 women, 11 men). The primary indication for surgery was degenerative disease (disc/stenosis) with associated “instability”; 11 of 31 (35%) patients had had prior spinal surgery. In 32% cases, 1 level was instrumented, in 52% 2 levels, 13% 3 levels, and 3% 4 levels. Thirteen of 31 (42%) patients underwent additional decompression.

Results. 

Within the 2-year follow-up period, 6 of 31 (19%) patients had required or were scheduled for a further surgical intervention. At follow-up, mean (SD) back and leg pain (0–10 VAS) were 4.7 (3.2) and 3.8 (3.6), respectively. The following global outcomes were reported: back symptoms, 67% improved, 30% same, 3% worse; leg symptoms, 64% improved, 21% same, 14% worse; ability to do physical activities/sports, 40% improved, 33% same, 27% worse; quality of life, 50% improved, 37% same, 13% worse; how much the operation helped, 29% helped a lot, 23% helped, 10% only helped a little, 35% didn’t help, 3% made things worse.

Conclusion. 

The results of the present study indicate that both back and leg pain are, on average, still moderately high 2 years after instrumentation with the Dynesys system. Only half of the patients declared that the operation had helped and had improved their overall quality of life; less than half reported improvements in functional capacity. The reoperation rate after Dynesys was relatively high. The results provide no support for the notion that semirigid fixation of the lumbar spine results in better patient-oriented outcomes than those typical of fusion.

In Brief

Patient-oriented outcome was examined in 31 consecutive patients (100% follow-up) with at least 2 years follow-up after Dynesys semirigid fixation. Approximately half the patients reported that the operation “helped/helped a lot” (52%) and rated their quality of life as “improved” (50%); approximately 40% reported an “improved” functional capacity. The results suggest that semirigid fixation of the lumbar spine does not result in better patient-oriented outcomes than those typical of fusion.