68 - Anatomical Consideration of Iliac Crest on Percutaneous Endoscopic Dis...

General Session: Endoscopic Surgery

Presented by: F. Tezuka - View Audio/Video Presentation (Members Only)

Author(s):

F. Tezuka(1), T. Sakai(1), K. Yamashita(1), Y. Takata(1), K. Higashino(1), A. Nagamachi(1), K. Sairyo(1)

(1) Tokushima University, Orthopedics, Tokushima, Japan

Abstract

Introduction: Percutaneous endoscopic discectomy (PED) is a minimally invasive procedure for the surgical treatment of lumbar disc herniation (LDH). It can be performed under local anesthesia and it requires only 8 mm of skin incision, and also with minimal disruption of the spinal structures including ligaments and muscles. However, when we perform PED with transforaminal (TF-PED) approach for lower lumbar spine, there are some problems such as interference with iliac crest. The purpose of this study is to assess the operability of TF-PED for lower lumbar spine.

Materials and Methods: We retrospectively reviewed the contrast-enhanced multi-planar abdominal computed tomography (CT) scans of 323 consecutive subjects (203 male and 120 female) in our hospital from April, 2009 through March, 2013. The mean age was 66.5 years old (range 15 - 89). We defined the tangent line in iliac crest and superior articular process of caudal spine as the trajectory line of TF-PED, and evaluated maximum inclination angle of the trajectory of the TF-PED (α angle) at L4-L5 and L5-S1 disc level. Assuming the use of oblique viewing endoscope of 25 degrees, we defined that α degree was 65 or more 65 degrees as operability of TF-PED.

Results: 1) Relationship between iliac crest and disc level: Trajectory of the TF-PED interfered with iliac crest at L4-L5 in 40.2% (right) / 54.5% (left) subjects, at L5-S1 in 99.7% / 100% subjects. 2) Maximum inclination angle of the trajectory of TF-PED: α angle was 84.3 degrees / 82.3 degrees at L4-L5 and 56.8 degrees / 55.2 degrees at L5-S1. 3) Operability of TF-PED: We can perform TF-PED in 94.4% / 90.4% subjects at L4-L5. In contrast, we can perform it in 24.1% / 19.2% subjects at L5-S1 (male: 15.8% / 10.8%, female: 38.3% / 33.3%). 4) Laterality of α angle: There were more male subjects than female subjects who had significant difference in angles more than 10 degrees at L4-L5 disc level (p=0.007). There was no significant difference at L5-S1 (p=0.771). At both disc levels, average age of subjects with laterality of more than 10 degrees was significantly higher than those of less than 10 degrees (L4-L5: p=0.023, L5-S1: p=0.010).

Conclusion: From the results of this study, trajectory of TF-PED may be limited by its surrounding anatomical structures. Maximum inclination angle indicated that treatment for the central type of LDH at L5-S1 disc level was considered more difficult than at L4-L5 due to iliac crest. However, in the clinical setting, we make an effort to perform TF-PED for more cases of LDH at L5-S1 with hand-down technique or foraminoplasty. Moreover, we found that we must consider about laterality of the trajectory of TF-PED in the age or sex.