General Session: Value and Outcomes in Spine Surgery - Hall F

Presented by: D. Park

Author(s):

D. Park(1), S. Ahquist(1), H. Park(1), A. Shamie(1)

(1) UCLA, Orthopaedic Surgery, Santa Monica, CA, United States

Abstract

Introduction: Lumbar fusion techniques vary in approach and technique to provide stability and restore anatomy. The critical importance of sagittal balance and pelvic parameters is well established in spinal deformity and lumbar degenerative surgery alike. The literature regarding the various lumbar fusion techniques have demonstrated satisfactory fusion rates and success, however, the comparative effects on sagittal balance and pelvic parameters remain unclear.

Methods: This retrospective study compared the radiographic impact of various lumbar fusion techniques involving a single level (ALIF, DLIF, TLIF, PLF) on sagittal alignment and pelvic parameters. Radiographic measurements were performed on pre-operative and post-operative lateral lumbar radiographs, and included segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence (PI), pelvic incidence-lumbar lordosis mismatch (PI-LL). Demographic data included age, gender, approach, diagnosis, surgical level, and implant lordosis. Independent sample t-test, paired sample t-test, McNemar Test, and one-way ANOVA were used to establish statistical significance. Linear regression was performed to determine a predictive model for lordosis from implant lordosis, fusion technique, and surgical level.

Results: 164 patients (78 males, 86 females) were analyzed with a mean age of 60.1 years and average radiographic follow up time of 9.3 months. These included 34 ALIF, 23 DLIF, 63 TLIF, and 44 PLF surgeries. ALIF and DLIF significantly improved SL (7.9° & 4.4° respectively; p < 0.0005), LL (5.3° & 7.7° respectively; p < 0.0005), and PI-LL (-2.8°, p = 0.05 & -6.9°, p < 0.0005 respectively). TLIF significantly improved SL (1.7°, p = 0.02) and LL (2.7°, p = 0.006) to a lesser extent, but did not improve PI-LL (p = 0.16). No significant differences were found between ALIF and DLIF in these parameters. Both ALIF and DLIF significantly outperformed PLF with the pre-operative to post-operative change in SL (8.2°, p < 0.0005 & 4.7°, p = 0.001 respectively) and LL (5.8°, p = 0.002 & 8.1°, p < 0.0005 respectively). Additionally, ALIF and DLIF significantly outperformed TLIF in the change of SL (6.2°, p < 0.0005) and LL (4.9°, p = 0.019). Only ALIF significantly improved the proportion of patients with a PI-LL ≤ 10° (0.46 to 0.71, p = 0.02). Lordotic cages significantly increased SL (4.7°, p < 0.0005), LL (4.3°, p < 0.0005), and PI-LL (-3.7°, p = 0.02) as compared to non-lordotic cages. Implant lordosis, fusion technique, and surgical level significantly predicted post-operative SL (p < 0.0005, R2 = 0.56, mIL = 1.1, mlevel = 7.19, mALIF = 6.53). Discussion and

Conclusions: This radiographic study demonstrated that various lumbar fusion techniques yielded differing radiographic outcomes. ALIF and DLIF produced greater improvements in radiographic measurements post-operatively as compared to TLIF and PLF. TLIF did not significantly improve PI-LL, an important parameter relating to sagittal balance. Lordotic implants provided better sagittal correction. Given the importance of sagittal balance and pelvic parameters, this study provides data to surgeons selecting between fusion techniques towards achieving improved alignment.