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.

Lumbar disc height and vertebral Hounsfield units: association with interbody cage subsidence

“…Multiple studies have validated the correlation between HUs as measured on CT and BMD on dual-energy x-ray absorptiometry to determine bone quality and fracture risk, as well as the utility of HU measurement as an opportunistic surrogate for quantitative BMD assessment. [12][13][14][15][20][21][22] Hendrickson et al reported excellent reproducibility and accuracy in identifying osteoporosis of the spine using CT attenuation measures such as HUs. 11 Our study demonstrated a significant trend of lower lumbar vertebral body HUs in the subsidence group, and corroborates the work of several studies demonstrating low BMD to be a risk factor for subsidence.…”

A Review and Clinical Perspective of the Impact of Osteoporosis on the Spine

“…Fragility fracture and osteoporosis epidemiology References: 1,2,7-21 Treatment strategies and treatment deficiencies following fragility fracture References: [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Bone health and elective spine surgery outcomes References: 3,5,6, Osteoporosis treatment and elective spine surgery outcomes References: 8,39,[60][61][62][63][64][65][66][67][68] Table 3. 2016 AACE Diagnosis of Osteoporosis in Postmenopausal Women.…”

“…Investigations have shown an association between low BMD and poor pedicle screw purchase, demonstrating that patients with osteoporosis are at increased risk of screw loosening, hardware failure, and interbody cage subsidence. 5,36,[41][42][43][44][45]46 The diminished bone density of cancellous bone and the associated increase in bone porosity in patients with osteopenia or osteoporosis contributes to implant failure by changing the vertebrae's ability to load share. 47 In a synthetic bone model, Varghese et al assessed pedicle screw pullout strength at different bone densities, finding significantly reduced pullout strength in the severely osteoporotic model.…”

“…45 Additionally, Formby et al and Tempel et al both report that low BMD is associated with significantly increased cage or graft subsidence in patients undergoing transforaminal lumbar interbody fusions or lateral lumbar interbody fusions, respectively. 36,46 Nonunion is another complication seen more commonly in patients with osteoporosis. 3,50,51 In the study by Bjerke et al, nonunion occurred in 46% of osteoporotic patients compared to 19% of patients with normal bone.…”

“…45 Additionally, Formby et al and Tempel et al both report that low BMD is associated with significantly increased cage or graft subsidence in patients undergoing transforaminal lumbar interbody fusions or lateral lumbar interbody fusions, respectively. 36,46…”