Total lumbar disc replacement: different results for different levels.

STUDY DESIGN

Prospective study analyzing midterm clinical results of total lumbar disc replacement (TDR) with ProDisc II performed at different lumbar motion segments.

OBJECTIVES

To assess the influence of the disc level and number of discs replaced following TDR on postoperative outcome.

SUMMARY OF BACKGROUND DATA

Multisegmental disc replacement procedures belong to the so-called "off-label" indications for disc replacement, which still lack evidence of noninferiority when compared with fusion procedures. Results from uncontrolled clinical trials regarding monosegmental versus multisegmental disc replacements are contradictory.

METHODS

The influence of the level and the number of lumbar discs replaced on postoperative outcome was analyzed prospectively according to Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and numerous clinical parameters. Post-TDR pain patterns were analyzed with fluoroscopically guided spine infiltrations.

RESULTS

A total of 99 patients from 3 treatment groups with a mean follow-up of 25.8 months (range, 12.1-57.5 months) achieved significant improvement of preoperative VAS and ODI levels (P < 0.05). Best results and highest patient satisfaction rates (90.9%) were achieved in patients with monosegmental TDR at L4-L5 (n = 22). Results deteriorated when monosegmental TDR was performed at the lumbosacral junction (n = 57) with a tendency toward statistical significance at 24-month follow-up (P = 0.07). Postoperative outcome was significantly inferior following bisegmental disc replacements at L4-L5 + L5-S1 (n = 20) with a considerably higher complication rate when compared with monosegmental TDR procedures. Fluoroscopically guided spine infiltrations confirmed that the incidence of postoperative pain from posterior joint structures was 9.1% (n = 2) for L4-L5 TDR, 28.1% (n = 16) following L5-S1, and 60.0% (n = 12) for bisegmental-TDR at L4-L5 + L5-S1, respectively.

CONCLUSION

The level and the number of lumbar disc replacements influence postoperative outcome significantly. Satisfactory outcome was achieved for monosegmental L4-L5 and L5-S1 disc replacement procedures with best results achieved following TDR at L4-L5. For bisegmental TDR, complication rates are significantly higher and inferior postoperative results are to be expected. The incidence of postoperative pain originating from facet and/or iliosacral joints is currently underestimated and will require further investigation.