Clinical and Radiographic Outcomes of Transforaminal Lumbar Interbody Fusion in Patients with Osteoporosis

Abstract

Study Design Retrospective review. Objective To compare clinical outcomes after transforaminal lumbar interbody fusion (TLIF) in patients with and patients without osteoporosis. Methods We reviewed all patients with 6-month postoperative radiographs and computed tomography (CT) scans for evaluation of the interbody cage. CT Hounsfield unit (HU) measurements of the instrumented vertebral body were used to determine whether patients had osteoporosis. Radiographs and CT scans were evaluated for evidence of implant subsidence, migration, interbody fusion, iatrogenic fracture, or loosening of posterior pedicle screw fixation. Medical records were reviewed for persistence of symptoms or recurrence of symptoms. Results The final data analysis included 18 (20.5%) patients with osteoporosis and 70 (79.5%) patients without osteoporosis. Males comprised 50% of patients with osteoporosis, and 64.3% of patients without osteoporosis. The mean age was significantly higher in the osteoporotic group (65.2 years) versus the nonosteoporotic group (56.9 years; p < 0.0001). We found significantly higher rates of subsidence (72.2 versus 45.7%, p = 0.05) and iatrogenic fractures (16.7% versus 1.4%, p = 0.03) in the osteoporotic group. In addition, the osteoporotic group had significantly higher radiographic complication rates compared with the nonosteoporotic group (77.8 versus 48.6%, p = 0.03). There was no difference between groups for revision surgery (16.6 versus 14.3%, p = 0.78) or postoperative symptoms (44.4% versus 50.0%, p = 0.69). Conclusions Our data demonstrated significantly increased rates of cage subsidence, iatrogenic fracture, and overall radiographic complications in patients with osteoporosis. However, these radiographic complications did not predispose patients with osteoporosis to an increased risk of surgical revision or worse clinical outcomes.

Keywords: Hounsfield units; computed tomography; lumbar fusion; osteoporosis; transforaminal lumbar interbody fusion.

Fig. 1

(A) Immediate postoperative and (B) 2-year follow-up sagittal computed tomography (CT) scans of a 53-year-old man who underwent L4–L5 transforaminal lumbar interbody fusion. The patient had Hounsfield unit (HU) measurements on immediate postoperative CT scan consistent with osteoporosis (average L4 HU = 105.7). Interbody cage subsidence into the superior end plate of L5 with interspace collapse is evident (9.9 mm), with evidence of increased fusion mass in the anterior column. However, at 26-month clinical follow-up, he had no recurrence of symptoms.