Cadaveric Analysis of the Kambin's Triangle

Abstract

IntroductionKambin’s Triangle is a right triangle over the dorsolateral disc. The area of this right triangle currently serves as a strategic site of posterolateral, minimally invasive access to the nerve root for delivery of epidural steroid injections. This posterolateral approach has also been considered a safe area of access to the intervertebral disc space and, thus, an effective approach in reducing complications, such as violation of the thecal sac, the nerve root, or the bony elements of the spine during minimally invasive spinal surgery. No published studies have been performed to characterize the dimensions of the Kambin's Triangle. Our aim is to characterize its dimensions at the lumbar levels and determine its efficacy and safety as a site of access for minimally invasive spinal surgery.MethodsTwo randomly chosen adult male cadavers were used for this study. The measurements were made bilaterally at their lumbar levels (L1–L5), which equates to 16 total measurements (eight bilateral disc spaces on two cadavers). The disc space was first accessed using a Kirschner wire in a standard oblique approach. With the assistance of fluoroscopy, a Kirschner wire was passed into the disc through the Kambin’s Triangle. The procedure was performed on the cadavers bilaterally at four levels, followed by open dissection. The calculations of the area were made by measuring the exiting nerve root, the superior border of the caudal vertebra, and the superior articulating facet—the borders of the Kambin's Triangle.ResultsThe Kambin’s Triangle height and width respectively averaged at 12 mm and 10 mm (L1–L2), 13 mm and 11 mm (L2–L3), 17 mm and 11 mm (L3–L4), and 18 mm and 12 mm (L4–L5). Thus, the area at each level was 60 mm2 (L1–L2), 71.5 mm2 (L2–L3), 93.5 mm2 (L3–L4), and 108 mm2 (L4–L5). All dissected levels demonstrated adequate anchoring of the Kirschner wire into the disc space with no evidence of nerve injury. Following this, a retractor was placed and complete discectomies were performed. All exiting nerves were protected in this safe zone and the thecal sac remained inviolate.ConclusionUnderstanding the Kambin’s Triangle will assist surgeons in the minimally invasive approach to spinal surgeries, with potentially safe placement of interbody cages through this strategic space.

Evaluation of the Lumbar Safety Triangle Through Magnetic Resonance Imaging

“…The measurements of the area of the triangles varied according to the level, being greater at the L3-L4 level. Hoshide, Feldman and Taylor 18 described a progressive increase of the areas measured for the triangles from L1-L2 to L4-L5. 18 In contrast, Hardenbrook et al 19 reported that the area of the triangles varied by level, which is in agreement with our findings.…”

“…Hoshide, Feldman and Taylor 18 described a progressive increase of the areas measured for the triangles from L1-L2 to L4-L5. 18 In contrast, Hardenbrook et al 19 reported that the area of the triangles varied by level, which is in agreement with our findings. These authors concluded that the safety triangle was a relatively large and safe area for minimally invasive procedures, contrary to the data presented by Ozer et al 15 One of the possible reasons to explain this incompatibility of findings between the studies would be the shape of the proposed triangles.…”

Transforaminal Insertion of a Thermocouple on the Posterior Vertebral Wall Combined with Hydrodissection during Lumbar Spinal Radiofrequency Ablation

“…The craniocaudal approach should always be favored to avoid transgressing the danger zone located at the anterior and superior parts of the foramina, which contains the radicular nerve and adjacent vessels. 6 The doubleoblique approach allows the safest passage (posterior and inferior) through the foramen. 7,8 In the aging spine, the anatomy of the foramen can, however, be modified by a bulging disc and/or osteophytes.…”

Oblique Fixation from Posterior Corner in Lumbar Spine Through Kambin’s Triangle: A Neuroimaging Anatomic Assessment

“…Hoshide R et al [34] 2 , respectively, which are all larger than the cross-sectional area (44.16 mm 2 ) of conventional working cannula (7.5 mm diameter) used in transforaminal endoscopic surgery. Since the cross-section of working cannula is circular, the corner of the triangle cannot be regarded as "operable" area, that is, there is a "invalid area" in Kambin's triangle.…”