654 - Clinical and Radiologic Results of Minimally Invasive Lateral Lumbar I...

General Session: MIS-3

Presented by: J.C. Lee - View Audio/Video Presentation (Members Only)


J.C. Lee(1), H.-D. Jang(1), S.-W. Choi(1), J.-H. Kim(2), B.-J. Shin(1)

(1) Soonchunhyang University, Orthopaedic Surgery, Seoul, Korea, Republic of
(2) Inje University Sanggye Paik Hospital, Orthopaedic Surgery, Seoul, Korea, Republic of



Background: Minimally invasive transpsoas lateral lumbar interbody fusion (LLIF) has been reported as an effective surgical option for various lumbar diseases. Many researchers reported high fusion rate and clinical excellence of LLIF with the use of bone morphogenic protein (BMP). However, there have been no studies on LLIF without the use of BMP.

Study Purpose: To analyze radiologic and clinical results of patients who underwent minimally invasive lateral lumbar interbody fusion without the use of BMP. Furthermore, we analyzed frequency of cage subsidence and its impact on the radiologic and clinical outcome.

Materials and Methods: Fifty patients and 109 levels treated by minimally invasive LLIF were included. There were 20 male and 30 female patients with the average age of 69 years. Average follow up period was 17.6 months (12-42months). Twelve patients received surgery on 1 level, 20 patients on 2 levels, 17 patients on 3 levels, and 1 patient on 4 levels, respectively. Operated levels were L1-2 in 5 cases, L2-3 in 27, L3-4 in 41, and L4-5 in 34, respectively. Graft material used for PEEK cage was autogenous bone only in 9 levels, autogenous bone and DBM in 19 levels, and DBM only in 81 levels. Radiologic evaluation included intervertebral disc height, segmental lordosis, lumbar lordosis, fusion rate, cage subsidence grade, and the bone mineral density. Radiologic fusion was determined by Bridwell's grade, and cage subsidence by Marchi's grade. Clinical outcome was evaluated by VAS of low back pain and leg pain, and ODI score. The above clinical and radiologic variables were analyzed statistically for comparison of cage subsidence and non-subsidence groups.

Result: Average LBP VAS was decreased from preoperative 5.5 to 2.2 at final follow-up, leg pain from 6.1 to 1.4, and ODI score from 25.6 to 12.9, with statistical significance (p< 0.001). Average disc height was increased from preoperative 5.9 mm to postoperative 11.5 mm, and subsequently decreased to 9.6 mm at final follow-up. Average lumbar lordosis increased from preoperative 18.6 degrees to postoperative 24.2 degrees, and 21.4 degree at final follow up. Radiologic fusion rate was 90.8%. Cage subsidence was observed in 6 levels (5.5%) on immediate postoperative radiograph; and in 20 levels (18.3%) at final follow-up. Comparison between cage subsidence and non-subsidence groups indicated no significant difference in age and BMD. Furthermore, preoperative and final follow-up measurement of disc height, VAS score of LBP and leg pain, and ODI score were not different between the 2 groups. However, pseudarthrosis rate and loss of lumbar lordosis was higher, and BMI was lower in subsidence group.

Conclusion: Minimally invasive LLIF was an effective surgical option with high fusion rate even without the use of BMP. Cage subsidence did not significantly deteriorate clinical outcome, however, it increased incidence of pseudarthrosis and loss of lumbar lordosis correction.

Keywords: minimally invasive lateral lumbar interbody fusion, degenerative lumbar disease, BMP, cage subsidence