Anatomical study and preliminary clinical application of modified posterior midline approach for lumbar surgery

English Keywords:Lumbar surgery  Posterior midline approach  Supraspinal ligament  Anatomy  Clinical application

English Abstract:

  【Abstract】 Objectives: To develop a modification of posterior midline approach with preservation of attachments of the supraspinal ligament in lumbar surgery. Methods: A total of fifty adult patients underwent lumbar surgery (27 male and 23 female, at a mean age of 37.1 years) were identified and MRI data were collected. Measurements were performed at axial image from L3/4 to L5/S1 respectively, including width and thickness of supraspinal ligament, thickness of thoracolumbar fascia and sacrospinal aponeurosis at attachments on spinal ligament and at multifidus cleavage. The mimic surgery was conducted in two adult cadavers to investigate the feasibility of this modified approach. Based on anatomy study, the modified posterior lumbar midline approach was applied clinically in 22 cases(12 male and 10 female, at a mean age of 51.5 years) with lumbar disorders. There were 14 cases in one-segment, 7 cases in two-segment and one case in three-segment. The incision length, exposure time and postoperative back pain were recorded. All cases were followed up for three months. Results: There were attachments of thoracolumbar fascia and sacrospinal aponeurosis on the postero-lateral part of supraspinal ligament. At the level of L3/4, L4/5 and L5/S1，the multifidus cleavage was located laterally from posterior midline in 16.32±6.56mm, 27.43±6.36mm, 33.65±4.77mm, respectively. The thickness of thoracolumbar fascia at the attachments was 0.81±0.17mm, 0.88±0.15mm, 0.87±0.14mm, respectively, almost equivalent to that at the multifidus cleavage(statistically significant only found at L4/5 level). The thickness of sacrospinal aponeurosis at the attachments was 1.76±0.51mm, 1.71±0.40mm, 1.78±0.50mm, respectively, with statistically significant more than that at multifidus cleavage at the same level(P<0.05). The mimic surgery showed the modified posterior lumbar midline approach was easier to be achieved with less retraction pressure. All the cases have received successfully decompression, interbody fusion and instrumentation with good exposure through this modified midline approach. The incision length was about 4cm for one-segment and 6cm for two-segment procedure. Conclusions: There are strong attachments of thoracolumbar fascia and sacrospinal aponeurosis on supraspinal ligament. The modified posterior lumbar midline approach with the aim of preserving those attachments is feasible, practical and effective with shorter incision length.