Long-term Outcome After Spinal Fusion for Isthmic Spondylolisthesis in Adults

Background Context: Data on the long-term outcome after fusion for isthmic spondylolisthesis are scarce.

Purpose: To study patient-reported outcomes and adjacent segment degeneration (ASD) after fusion for isthmic spondylolisthesis and to compare patient-reported outcomes with a control group.

Study Design/setting: A prospective study including a cross-sectional control group.

Patient Sample: Patients with isthmic spondylolisthesis underwent posterior lumbar interbody fusion (PLIF) (n=86) or posterolateral fusion (PLF) (n=77). Patient-reported outcome data were available for 73 patients in the PLIF group and 71 in the PLF group at a mean of 11 (range 5-16) years after baseline. Seventy-seven patients in the PLIF group and 54 in the PLF group had radiographs at a mean of 14 (range 9-19) years after baseline. One hundred thirty-six randomly selected persons from the population served as controls for the patient-reported outcomes.

Outcome Measures: Patient-reported outcomes include the following: global outcome, Oswestry Disability Index, Disability Rating Index, and Short Form 36. The ASD was determined from radiographs using the University of California Los Angeles (UCLA) grading scale.

Methods: The chi-square test or analysis of covariance (ANCOVA) was used for group comparisons. The ANCOVA was adjusted for follow-up time, smoking, Meyerding slippage grade, teetotaler (yes/no) and, if available, the baseline level of the dependent variable.

Results: There were no significant patient-reported outcome differences between the PLIF group and the PLF group. The prevalence of ASD was 42% (32/77) in the PLIF group and 26% (14/54) in the PLF group (p=.98). The patient-reported outcome data indicated lower physical function and more pain in individuals with surgically treated isthmic spondylolisthesis compared to the controls.

Conclusions: PLIF and PLF groups had similar long-term patient-reported and radiological outcomes. Individuals with isthmic spondylolisthesis have lower physical function and more pain several years after surgery when compared to the general population.