Clinical Outcomes Based on Preoperative Kambin's Triangular Working Zone Measurements on 3D CT/MR Fusion Imaging to Determine Optimal Approaches to Transforaminal Endoscopic Lumbar Diskectomy

Abstract

Background Transforaminal endoscopic lumbar diskectomy (TELD) is a widely used minimally invasive surgical procedure to treat herniated disks. Postoperative dysesthesia (POD) is a significant complication that affects patient satisfaction. Several anatomical and magnetic resonance (MR) imaging studies of the intervertebral foramina showed that TELD should be avoided in patients with small Kambin's triangular working zones. Recently, some reports indicated the usefulness of three-dimensional (3D) computed tomography/magnetic resonance (CT/MR) fusion images. To date, no articles have been published in the English literature regarding the use of 3D CT/MR fusion images before TELD to evaluate Kambin's triangular working zone. Our objective was to examine clinical outcomes when preoperative Kambin's triangular working zone measurements from 3D CT/MR fusion images were used to determine the approach to TELD. Patients and Methods We included 31 patients who underwent TELD. We rotated the 3D CT/MR fusion images from the posteroanterior view on the approach side to the angle at which Kambin's triangular working zone appeared the largest. This was used to determine the intraoperative insertion angle for the working cannula. When the perpendicular line extending from the exiting nerve at the intervertebral disk level to the upper margin of the superior articular process (exiting nerve-superior articular process distance [ESD]) was less than or equal to 7 mm, an approach that combined foraminoplasty with an outside-in technique (F + outside-in) was used. We compared ESD and clinical outcomes, such as POD, between the approaches. Results Surgical plans were based on ESD values from 22 patients. ESD was 7 mm in 21 patients, all of whom underwent F + outside-in. The inside-out approach was used in eight of nine patients who did not have ESD measurements. Of these, five patients had retrospective ESD measurements of 7 mm. The mean ESD was 6.3 ± 1.0 mm when inside-out was used and 4.4 ± 1.6 mm when F + outside-in was used, a significant difference. Significant improvements were observed in the visual analog scale scores for low back pain, lower limb pain, and lower limb paresthesia. There were no incidences of POD or intraoperative complications. Conclusion Based on preoperative Kambin's triangular working zone measurements from 3D CT/MR fusion images, F + outside-in should be selected when the working zone is smaller than the cannula diameter. This method successfully avoided POD in our study. Preoperative Kambin's triangular working zone measurements from 3D CT/MR fusion imaging can enhance patient safety during TELD.

Lumbar safety triangle: comparative study of coronal and coronal oblique planes in 3.0-T magnetic resonance imaging

“…We also found that, at all levels, the boundaries of the lumbar safety triangle were smaller in the coronal oblique plane than in the coronal plane, with the mean differences between the two planes being statistically significant for almost all measures. Recent studies have performed three-dimensional computed tomography ( 44 ) and MRI reconstructions in preoperative planning software ( 15 , 45 ) , suggesting the appropriate location and safe angulation for introducing the working cannulas ( 46 ) . However, those studies have not mentioned the measurements of the lumbar safety triangle at those angulations.…”

“…Although there have been many studies of the lumber safety triangle in cadavers, only a few have involved the use of MRI ( 12 , 13 , 14 , 15 , 16 ) . To our knowledge, there have been no studies analyzing the dimensions of the dorsal root ganglion and its relationship with the lumbar safety triangle in different planes.…”

How dimensions can guide surgical planning and training: a systematic review of Kambin’s triangle

“…For this reason, researchers have begun to test the efficacy of MRI/CT fusion to extract the benefits of both technologies. 7,45,46 Using either an artificial intelligence model or manual fusion, 3D visualizations have been created by merging MRI with CT images of the lumbar vertebrae. This methodology appears to compensate for the disadvantages of each individual scan and enables analysis of the relationship between the bony components and neural tissue of Kambin's triangle in 3D.…”

Current and Future Applications of the Kambin’s Triangle in Lumbar Spine Surgery

“…Consequently, there has been an interest in improving and evaluating preoperative imaging techniques to improve patient outcomes. Description of the use of 3D CT/magnetic resonance fusion imaging technique to evaluate Kambin's triangle found that the use of this technique preoperatively to acquire accurate measurements can enhance patient safety and outcomes in transforaminal endoscopic lumbar discectomy [37]. A more recent study used the same method with artificial intelligence (AI) to reduce processing time and evaluation of these preoperative studies, showing the importance of incorporating AI and deep learning to plan personalized and technically precise surgeries in the future [15].…”