Abstract
Posterior lumbar interbody fusion (PLIF) is a popular procedure for treating lumbar canal stenosis with spinal instability, and several reports concerning fusion assessment methods exist. However, there are currently no definitive criteria for diagnosing a successful interbody fusion in the lumbar spine. We suggested evaluating fusion status using computed tomography (CT) in extension position to detect pseudoarthrosis more precisely. The purpose of this study was to evaluate its usefulness for determining bone union quality after PLIF. Eighty-one patients who underwent PLIF at 97 levels were retrospectively enrolled. The study population included 48 men and 33 women (mean age 58.9 years, range 21–85 years). Patients were followed up for more than 12 months after surgery. The mean follow-up period was 27.6 months (range 14–49 months). Fusion status was evaluated using three ways: flexion–extension radiographs, CT images in flexion and extension position. In the flexion–extension radiographs, mobility of more than 3°, a remaining clear zone, or an uncertain bone connection constituted an incomplete union. For CT images, a remaining clear zone, a gas pattern, or an uncertain bone connection constituted an incomplete union. Flexion–extension radiographs demonstrated a solid fusion in 90.7% of the 97 levels at 10.7 months postoperatively. When fusion was demonstrated on flexion–extension radiographs, the rate of fusion affirmed by flexion CT and extension CT was 87.6 and 69.1% of the levels assessed, respectively. The rate of pseudoarthrosis detected on extension CT images was significantly higher than that on flexion–extension radiographs (P < 0.001) and flexion CT (P < 0.01). The rate of fusion achieved on extension CT was 85.6% at 15.1 months postoperatively. Extension CT could detect pseudoarthrosis more clearly than flexion–extension radiography and flexion CT. The CT images are influenced by body position and dilating anterior disc space in extension CT contributes to detect pseudoarthrodesis. Thus, extension CT was a useful method for assessing fusion status after PLIF.
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References
Blumenthal SL, Gill K (1993) Can lumbar spine radiographs accurately determine fusion in postoperative patients? Correlation of routine radiographs with a second surgical look at lumbar fusions. Spine 18:1186–1189
Brodsky AE, Evan SK, Momtaz AK (1991) Correlation of radiographic assessment of lumbar spine fusions with surgical exploration. Spine 16:S261–S265
Burkus JK, Transfeldt EE, Kitchel SH, Watkins RG, Balderston RA (2002) Clinical and radiographic outcomes of anterior lumbar interbody fusion using recombinant human bone morphogenetic protein-2. Spine 27:2396–2408
Chafetz N, Cann CE, Morris JM, Steinbach LS, Goldberg HI, Ax L (1987) Pseudarthrosis following lumbar fusion: detection by direct coronal CT scanning. Radiology 162:803–805
Cook SD, Patron LP, Christakis PM, Bailey KJ, Banta C, Glazer PA (2004) Comparison of methods for determining the presence and extent of anterior lumbar interbody fusion. Spine 29:118–123
Frymoyer JW, Matteri RE, Hanley EN, Kuhlmann D, Howe J (1978) Failed lumbar disc surgery requiring second operation: a long-term follow-up study. Spine 3:7–11
Herzog RJ, Marcotte PJ (1996) Imaging corner assessment of spinal fusion. Critical evaluation of imaging techniques. Spine 21:1114–1118
Kant AP, Daum WJ, Dean SM, Uchida T (1995) Evaluation of lumbar spine fusion. Plain radiographs versus direct surgical exploration and observation. Spine 20:2313–2327
Korovessis P, Repantis T, Papazisis Z, Iliopoulos P (2010) Effect of sagittal spinal balance, levels of posterior instrumentation, and length of follow-up on low back pain in patients undergoing posterior decompression and instrumented fusion for degenerative lumbar spine disease: a multifactorial analysis. Spine 15:898–905
Laasonen EM, Soini J (1989) Low back pain after lumbar fusion: surgical and computed tomographic analysis. Spine 14:210–213
Lang P, Genant HK, Chafetz N, Steiger P, Morris JM (1988) Three-dimensional computed tomography and multiplanar reformations in the assessment of pseudarthrosis in posterior lumbar fusion patients. Spine 13:69–75
McAfee PC, Boden SD, Brantigan JW, Fraser RD, Kuslich SD, Oxland TR, Panjabi MM, Ray CD, Zdeblick TA (2001) Symposium: a critical discrepancy: a criteria of successful arthrodesis following interbody spinal fusions. Spine 26:324–334
Rothman SLG, Glenn WV Jr (1985) CT evaluation of interbody fusion. Clin Orthop Rel Res 193:47–56
Santos ER, Goss DG, Morcom RK, Fraser RD (2003) Radiographic assessment of interbody fusion using carbon fiber cages. Spine 28:997–1001
Shah RR, Mohammed S, Saifuddin A, Taylor BA (2003) Comparison of plain radiographs with CT scan to evaluate interbody fusion following the use of titanium interbody cages and transpedicular instrumentation. Eur Spine J 12:378–385
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Nakashima, H., Yukawa, Y., Ito, K. et al. Extension CT scan: its suitability for assessing fusion after posterior lumbar interbody fusion. Eur Spine J 20, 1496–1502 (2011). https://doi.org/10.1007/s00586-011-1739-0
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DOI: https://doi.org/10.1007/s00586-011-1739-0