INTRODUCTION: We observed good clinical outcomes after posterolateral fusion (PLF) in terms of in situ fusion, a low incidence of adjacent segment disease (ASD), and the lack of need for slippage reduction in a long-term clinical and radiological follow-up study of PLF for degenerative lumbar spondylolisthesis (DLS). Furthermore, we previously found that facet fusion (FF) using a percutaneous pedicle screw (PPS) system as a minimally invasive evolution of PLF also resulted in good clinical outcomes. This study aimed to assess clinical outcomes 10 years after FF.
METHODS: The indications for lumbar fusion were: 1) sagittal translation ≥ 8% on a flexion-extension lateral radiograph or 2) anterior wedging ≥ 5 degrees on a flexion radiograph and a disc range of motion (ROM) ≥ 10 degrees. Sixty-nine of 104 consecutive patients (40 women, 29 men; mean age, 67.1 years; follow-up rate, 66.3%) who underwent FF for single-level DLS were retrospectively reviewed after a minimum follow-up of 10 years. The surgical method involved making a 5-cm skin incision, bilateral laminar fenestration, and FF with autologous bone harvested from the spinous process. PPS insertion was performed through the fascia. We evaluated the therapeutic effectiveness of FF using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), Roland-Morris Disability Questionnaire (RMDQ), and visual analogue scale (VAS) preoperatively and at 1 and 10 years postoperatively. The revision surgery rate was also evaluated.
RESULTS: The therapeutic effectiveness rate, determined using the JOABPEQ, slightly decreased in all categories from 1 to 10 years postoperatively; however, high effectiveness rate was still maintained, which was 74.5% of the patients in the Low Back Pain and 75.0% in the Walking Ability. Although the mean RMDQ value and VAS score were a little increased from 1 year postoperatively, good outcomes were maintained at 10 years postoperatively. There was no statistically significant difference between the VAS scores for low back pain, buttock and lower limb pain, and numbness in the buttocks and lower limbs at 1 and 10 years postoperatively. There were seven patients requiring revision surgery for ASD 1 to 10 years after the first surgery (revision surgery rate, 6.7%). Revision surgery for complications or poor clinical outcomes immediately after surgery was not required in any of the patients.
DISCUSSION: FF maintained good clinical outcomes 10 years postoperatively. The revision surgery rate of 6.7% at 10 years after FF was extremely low compared to previously reported rates at 10 years after interbody fusion. Considering that good RMDQ and VAS values were maintained, the decreased 10-year postoperative therapeutic effectiveness in Walking Ability, determined via the JOABPEQ, might have been a function of aging. Low back pain did not worsen 10 years after in situ fusion. Thus, FF is useful in the long-term management of DLS.