| Background and PurposeIn recent years,with the continuous development of spinal surgery to minimally invasive and precise direction,a number of minimally invasive lumbar interbody fusion methods have emerged,of which lateral approach lumbar interbody fusion(LLIF)is a relatively novel minimally invasive technique.The application of this technique was first reported by Ozgur in 2006 and named as extreme lateral approach lumbar interbody fusion(XLIF).Followed by a slightly different surgical instrument and operation,some scholars named it as direct lateral approach to lumbar interbody fusion(DLIF).The procedure does not pass through the peritoneum,so the invasion of the peritoneum and the retroperitoneal great vessels was eliminated;It is not necessary for the operators to learn minimally invasive techniques step by step,which the operate is under the direct view;The structure of the posterior lumbar tension band is not damaged during operation.It is unnecessary to drag the dural sac and spinal nerve,so as to reduce postoperative pain and dura fibrosis,and to maximize the postoperative stability of the lumbar spine.In addition,XLIF is highly advantageous in the treatment of degenerative lumbar instability and deformity because it allows direct access to the anterior column of the lumbar spine,and the area of the bone bed is large,which is convenient for correction of deformity and high fusion rate.The operation has less trauma,less blood loss,less postoperative pain,shorter hospitalization time and quicker recovery of activities of daily living.Therefore,as a safer,minimally invasive alternative to traditional lumbar interbody fusion,it is becoming more and more popular.However,some patients were reported to have symptoms of abnormal sensation or pain in the front of the inguinal area and the front of the thigh,and the weakness of the hip flexion and knee flexion after the operation.It was related to the injury of the psoas and the adjacent lumbar plexus during the process of separation of the psoas major,channel dilation,and the fixation of the distractor.This injury is more likely to occur in the decompression and fusion of the L4/5 intervertebral space Because the lumbar plexus moves closer to the ventral side of the psoas major as the segment of the lumbar surgery moves down,resulting in the safe working zone(SWZ)of XLIF approach moves forward and narrows simultaneously.Clinically,in the L4/5 intervertebral line lumbar interbody fusion(XLIF),it is often difficult to establish a surgical working channel due to abnormal distribution of the lumbar plexus,and even the case of cessation of surgery is reported,which is relate to the shape of the psoas major.Therefore,it is of great significance to accurately predict the distribution of the retroperitoneal great vessel and the position of the lumbar plexus for select the position of the psoas major into the lumbar interspace,establish the operation channel safely,complete the operation and prevent the vascular nerve injury.However,the current reports rarely involve the study of morphological variation in psoas major.This study is designed to analyze the morphology of the psoas major and its influence on the distribution of the retroperitoneal great vessel and the lumbar plexus in the L4/5 intervertebral space,and to clarify the relationship between them.Determine the safe working zone of the XLIF approach to provide a reference for the assessment of the risk of preoperative operation.Materials and MethodsAccording to the inclusion and exclusion criteria,180 cases of lumbar 3.0T magnetic resonance imaging data were included.Analyze the shape of the psoas major by measuring the longitudinal length and transverse length of the psoas major in the L4/5 intervertebral space by T2-weighted axial magnetic resonance imaging;To analyze the two dissection of the psoas major and its influence on the distribution of the retroperitoneal great vessel and the lumbar plexus in the L4/5 intervertebral space.SPSS 22.0 statistical software was used for analysis.P<0.05 indicated that the difference was statistically significant.Results1.Compared with the non-"teardrop-shaped" psoas major,the "teardrop-shaped" psoas major has a longer longitudinal axis,a shorter transverse axis,and a larger ratio between the longitudinal axis and the transverse axis.The difference is statistically significant.(P < 0.05).2.Compared with the non-"teardrop-shaped" psoas major,in the subjects with the "teardrop-shaped" psoas major on the left side,the distribution proportion of the left retroperitoneal large artery at the junction of A zone and I zone is significantly higher.The difference is statistically significant(P<0.05).3.Compared with the non-"teardrop-shaped" psoas major,in the subjects with the "teardrop-shaped" psoas major on the right side,the distribution proportion of the right retroperitoneal large vein at zone I is significantly higher.The difference is statistically significant(P<0.05).4.Compared with the non-"teardrop-shaped" psoas major,in the subjects with the "teardrop-shaped" psoas major on the left side,the distribution proportion of the left lumbar plexus at zone II and the junction of zone II and zone III is obvious increased.5.Compared with non-"teardrop-shaped" psoas major,in the subjects with the "teardrop-shaped" psoas major on the right side,the distribution proportion of right lumbar plexus at zone II and the junction of zone II and zone III is obvious increased.6.When XLIF is performed at the level of L4/5 intervertebral space,the left surgical safety zone in the subjects with the non-"teardrop-shaped" psoas major is zone II,and the right surgical safety zone is zone II;There is no absolute surgical safety zone on both the left and right sides in the subjects with the "teardrop-shaped" psoasmajor.Conclusions1.Compared with the non-"teardrop-shaped" psoas major,the "teardropshaped" psoas major has a longer longitudinal axis,a shorter transverse axis,and a larger ratio of the longitudinal axis and the transverse axis.2.Compared with the non-"teardrop-shaped" psoas major,in the subjects with the "teardrop-shaped" psoas major,the location of the retroperitoneal great vessel is more backward,and the location of the lumbar plexus are more forward.3.When XLIF is performed at the level of L4/5 intervertebral space,the "teardrop-shaped" psoas major may increase the risk of neurovascular injury compared to non-"teardrop-shaped" psoas major,and in both forms of psoas,the risk of the right approach is higher than the left side. |
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