Anatomy of the psoas muscle and lumbar plexus with respect to the surgical approach for lateral transpsoas interbody fusion

Abstract

Lateral transpsoas interbody fusion (LTIF) is a minimally invasive technique that permits interbody fusion utilizing cages placed via a direct lateral retroperitoneal approach. We sought to describe the locations of relevant neurovascular structures based on MRI with respect to this novel surgical approach. We retrospectively reviewed consecutive lumbosacral spine MRI scans in 43 skeletally mature adults. MRI scans were independently reviewed by two readers to identify the location of the psoas muscle, lumbar plexus, femoral nerve, inferior vena cava and right iliac vein. Structures potentially at risk for injury were identified by: a distance from the anterior aspect of the adjacent vertebral bodies of \20 mm, representing the minimum retraction necessary for cage placement, and extension of vascular structures posterior to the anterior vertebral body, requiring anterior retraction. The percentage of patients with neurovascular structures at risk for leftsided approaches was 2.3% at L1-2, 7.0% at L2-3, 4.7% at L3-4 and 20.9% at L4-5. For right-sided approaches, this rose to 7.0% at L1-2, 7.0% at L2-3, 9.3% at L3-4 and 44.2% at L4-5, largely because of the relatively posterior right-sided vasculature. A relationship between the position of psoas muscle and lumbar plexus is described which allows use of the psoas position as a proxy for lumbar plexus position to identify patients who may be at risk, particularly at the L4-5 level. Further study will establish the clinical relevance of these measurements and the ability of neurovascular structures to be retracted without significant injury.

Neurologic deficit following lateral lumbar interbody fusion

“…2 shows, the rate of anterior groin/thigh pain drops significantly over the follow-up time. This might be attributed to a transient irritation of the genitofemoral nerve damage which crosses at L2-3 [5,9]. Surgeons have theorized that this may be related to direct cutaneous nerve neuropraxia or an indirect mechanism via a psoas muscle inflammatory response due to mechanical dissection.…”

“…Although Park et al [6] showed that the lumbar plexus with hip flexion travels more anterior (non-significant) the advantages of a relaxed and therefore easier-to-dissect muscle seem to out weigh the change in position of the nerves. The deciding factor for the side of the approach should be the anatomy of the psoas muscle relative to the approached disc level as described by Kepler [9]. Other critical factors are the relationship of the pelvis to L4-5 level, the coronal angulation of the approached disc space and the side of the concavity of the curve.…”

Lateral Lumbar Interbody Fusion

“…Preoperative magnetic resonance imaging can be helpful to identify the position of the psoas and the approximate locations of the lumbar plexus and vascular structures, although the operative position (lateral decubitus with hips and knees flexed) is quite different than the supine position [1,[4][5][6][7].…”

“…Furthermore, biomechanical studies show that LLIF implants provide a greater reduction in range of motion during flexion, extension, lateral bending, and axial rotation when compared to those of anterior lumbar interbody fusion and TLIF implants [15,16]. The most common complication is anterior thigh pain and numbness, which result from irritating the psoas muscle or transient irritation of the genitofemoral nerve [1,4,5,8]. Pumberger et al [17] examined 181 patients at our institute.…”

Lateral access surgery: a decade of innovation

“…In 2011, two articles [2,3] provided important knowledge on the regional neural and vascular anatomy related to the transpsoas approach, providing quantitative and qualitative data to better understand and control the risk of injury to the lumbar plexus. In 2012, a retrospective study [4] on the neurological safety of the procedure (one of the hottest topics related to transpsoas surgery) was published in the Journal.…”