Selection of retroperitoneal access during intervertebral disc endoprosthesis in lumbar spine

The morphometric parameters and surgical areas of risk of retroperitoneal approach were studied for endoprosthetics of intervertebral discs in the lumbar spine to reduce trauma and reduce the risk of complications. The study included 110 patients operated on in the period from 2017 to 2020 (72 men, 38 women) in the neurosurgical department of the 1586 Military Clinical Hospital. The average age of the patients was 44.9 ± 15.4 years. According to the localization of access to the lumbar spine, the patients were distributed as follows: L_III–L_IV — 8 (7.3%), L_IV–LV — 46 (41.7%), L_V–S_I — 56 (51%). It was found that, for the intervertebral disc L_V – S_I, the length of the skin incision was 92.5 (80; 100) mm, the length of the surgical wound was 80 (80; 110) mm, the thickness of the subcutaneous fat layer was 30 (15; 40) mm, the depth of the wound was to the spine — 85 (70; 120) mm, the depth of the wound to the spinal canal — 125 (107.5; 152.5) mm, the angle of operation in the horizontal plane at the level of the spine — 52 (47; 59.5) degrees. On the basis of the anthropometric data of patients, the optimal length of the skin incision was determined for performing the retroperitoneal approach (120 mm for level L_III–L_IV, 100 mm — for level L_IV–L_V). Three variants of the inferior vena cava bifurcation have been identified for different levels of intervertebral discs in the lumbar spine: high bifurcation, left common iliac vein mainly overlaps the left half of the L_IV–L_V intervertebral disc and does not overlap the L_V–S_I intervertebral disc; middle bifurcation, left common iliac vein overlaps the central part of the intervertebral discs L_IV–L_V and L_V–S_I; low bifurcation, inferior vena cava overlaps the right side of the intervertebral disc L_IV–L_V, inferior vena cava and left common iliac vein completely overlap the intervertebral disc L_V–S_I. The data obtained can be used when planning retroperitoneal access to the lumbar spine in order to reduce the trauma of the operation.