Surgical safe zones for oblique lumbar interbody fusion of L1‐5: A cadaveric study

Abstract

To evaluate the operating range and morphology of the surgical safe zone for oblique lumbar interbody fusion (OLIF). Twenty embalmed full-torso cadaveric specimens were dissected. The oblique corridor and the distance between adjacent lumbar arteries were measured in a static state and with psoas major retraction. The morphology and size of the safe zone for OLIF and the location of the lumbar sympathetic trunk were also recorded. The oblique corridor of the L1-L5 segments was significantly greater in the retracted state than in the static state (p < 0.05). With psoas major retraction, the distances between adjacent lumbar arteries at L1-4 were significantly greater (p < 0.05) than those in the static state. The lumbar sympathetic trunk is just located in the safe zone and travels downward adjacent to the psoas major. The shape of the safe zone for OLIF was approximately an oblique upward parallelogram at L1/2 and L2/3, an isosceles trapezoid at L3/4, and an irregular quadrangle or triangle at L4/5. The safe zone for OLIF at L1/2, L2/3, and L3/4 was significantly larger during retraction than in the static state (p < 0.05). On the lateral side of the lumbar spine there is a natural surgical safe zone for OLIF, which can provide a sufficient operating space. The safe zone has a certain morphological pattern in L1-5 segments and psoas major retraction can significantly enlarge it.

An Expanded Surgical Corridor of Oblique Lateral Interbody Fusion at L4–5: A Magnetic Resonance Imaging Study

“…17,18 During surgical dissection, the surgeon could create adequate surgical access to the targeted intervertebral disc space by retracting the surrounding structures away from the surgical corridor. 15,19 In a cadaveric study conducted by Davis et al, 15 it was found that retraction of the psoas muscle can increase accessibility to the lumbar spine by approximately 6.9-9.45 mm. The psoas muscle retraction could increase the surgical corridor's width at the L4-5 level by an average of 58.97%, or approximately 9.45 mm.…”

“…17,18 The surgical corridor can be expanded through psoas muscle retraction up to the minimum corridor width required during the surgical approach to the targeted intervertebral disc level. 15,19 Although the narrow or no oblique corridor is not an absolute contraindication for performing OLIF, it does require surgical expertise to manipulate the psoas muscle and widen the corridor for proper exposure of the operated disc space and cage insertion.…”

“…20 On the other hand, studies also showed that the psoas muscle could also be retracted during the OLIF. 15,19 Those structures can safely be mobilized while approaching the disc space. So, the accessible surgical corridor for the anterior-to-psoas approach could be wider than previously described in the literature.…”

“…So, the accessible surgical corridor for the anterior-to-psoas approach could be wider than previously described in the literature. 9,[14][15][16]19 The aim of this study is to introduce a new preoperative evaluation method, an "expanded surgical corridor, " to define the potential actual safety corridor, which may expand the possibility of performing the OLIF surgery, particularly in patients with a narrow or no surgical corridor, as classified by the conventional surgical corridor (CSc).…”

“…Regarding the preoperative radiographic evaluation, a distance of approximately 10 mm between the psoas muscle and the major vessels is typically considered the minimum width required for performing OLIF [ 17 , 18 ]. The surgical corridor can be expanded through psoas muscle retraction up to the minimum corridor width required during the surgical approach to the targeted intervertebral disc level [ 15 , 19 ]. Although the narrow or no oblique corridor is not an absolute contraindication for performing OLIF, it does require surgical expertise to manipulate the psoas muscle and widen the corridor for proper exposure of the operated disc space and cage insertion.…”