Introduction: Although lumbar spinal stenosis (LSS) adjacent to degenerative spondylolisthesis (DS) is often observed, surgical treatment for such conditions remains controversial. When decompression surgery is performed concomitantly adjacent to a posterior lumbar interbody fusion (PLIF) segment, there is concern about progressive degeneration and instability at the decompressed segment. The purpose of this study was to examine the effects of concomitant decompression adjacent to the PLIF segment on the clinical and radiological outcomes 5 years after surgery for multilevel LSS with DS.
Patients and Methods: This was a retrospective 1:1 matched case-control study. Forty-five consecutive patients who had undergone L3/4 posterior decompression with L4/5 PLIF for multilevel LSS with DS were enrolled from 2005 to 2011 (group D). As a control group, 45 age, sex and preoperative disc height at L3/4-matched patients who had undergone L4/5 PLIF alone for L4/5DS were randomly selected (group A). Disc height, vertebral slippage, range of motion (ROM) of the disc angle, posterior opening angle, segmental lordotic angle, presence of the intradiscal vacuum phenomenon (IVP) at the L3/4 level, and lumbar lordosis at L1-S were measured on lateral radiographs. Radiological parameters were compared between the groups. In terms of clinical outcomes, the Japanese Orthopaedic Association (JOA) score and the requirement for additional L3/4 surgery were evaluated.
Results: In terms of pre/postoperative radiological parameters, group D showed significant differences in disc height (9.4 mm/7.4 mm) and the presence of IVP (7 cases; 15%/22 cases; 49%) (P<0.01), while in group A, a significant difference was observed in disc height (9.9 mm/9.0 mm) (P<0.05). There were no significant differences in other radiological parameters. In terms of pre/postoperative radiographic changes between the groups, significant differences were detected regarding disc height narrowing of ≥ 3 mm (group D 31%, group A 9%) and IVP (group D 33%, group A 11%). The recovery rate of the JOA score was 58% for patients in group D and 61% for those in group A (P=0.63). The reoperation rate at the L3/4 level was 2.2% (1 of 45) in group D and 6.7% (3 of 45) in group A.
Discussion: Concomitant decompression adjacent to the PLIF segment accelerated adjacent disc degeneration compared to PLIF alone, but it did not predispose to the development of instability 5 years after surgery. Moreover, the clinical outcomes were not significantly different between group D and group A. Hence, these results suggest that concomitant decompression adjacent to the PLIF segment may be an effective operative method for multilevel stenosis with DS.