| PartⅠ An MRI study of the oblique corridor and the trajectory to the L1-L5 intervertebral discs in the lateral positionObjective:To study the applied anatomical parameters of L1-L5 oblique lateral lumbar interbody fusion(OLIF)and the shape of psoas muscle in L4-5 space,and to explore the relationship between the operation channel and surrounding tissues.Methods:Magnetic resonance imaging(MRI)data of 118 adult lumbar vertebrae were collected.The anatomic parameters of Ll-2,L2-3,L3-4 and L4-5 OLIF were observed:vascular window,safe ty window,psoas major muscle window,and the width,thickness and cross-sectional area of the left psoas major muscle on the coronal plane of the intervertebral space.Results:The safety windows of L2-3,L3-4 and L4-5 in male were larger than those in female.The maximum distance of BC in L3-4 was 14.69±4.84,followed byL2-3:14.34 × 4.62;L1-2 was 13.91±4.15,the minimum distance of L4-5 was 10.99± 5.56;the size of AB in L4-5 was the largest,followed by L3-4,L2-3 and L1-2.On the coronal plane of L4-5,the width of the left psoas muscle was the largest,followed by L3-4,L2-3 and L1-2.BC was negatively correlated with AB,CD,HD,DF and PCS A,and there was type Ⅳ psoas muscle(high-rising psoas)in L4-5 intervertebral space.Conclusions:Compared with previous studies,the safe surgical area of the Chinese is generally smaller than that of Caucasian.The position of the retroperitoneal the safety window is vital potential to limit the corridor and trajectory.The preoperative assessment of vertebral parameters,especially the safety window,is essential for planning surgical process.Part Ⅱ Anatomical Study of the Lumbar Segmental Arteries in Relation to the Oblique Lateral Interbody Fusion ApproachObjective:To use computed tomography angiography to evaluate the regional anatomy of the lumbar segmental arteries(LAs)associated with the surgical field in oblique lateral interbody fusion(OLIF).Methods.Computed tomography angiography images from 50 patients were reviewed.In the sagittal plane,distances from the LA to the upper and inferior edges of the vertebral body were measured in the anterior quarter of the anterior and median lines of the intervertebral disc(IVD).LAs were classified as types Ⅰ-Ⅳ based on the zone in which they passed through the vertebral body.Results.The LA branch angles were acute(<90°)at L1-L3 and blunt(>90°)at L4-L5.The average distances from the LA to the upper and inferior edges of the vertebral body in the anterior quarter position revealed that La1.2>Lb1.2 and Lb3.4.5>La3.4.5.For the IVD of L1-L2,Lb1<La2;IVD of L2-L3,Lb2<La3;IVD of L3-L4,Lb3>La4;IVD of L4-L5,Lb4>La5.In zone I,the most frequent LA type was type Ⅳ at L1(n=41;85.4%)and L2(n=42;84.0%),type III at L3(n=20;40.0%),and type II at L4(n=36;80.0%)and L5(n=5;83.3%).In zone Ⅱ,the most frequent LA type was typeⅢ at L1(n=38;79.2%),L2(n=39;78.0%),L3(n=43;86.0%),and L4(n=28;62.2%),while type Ⅱ was the most frequent LA type at L5(n=5;83.3%).In zone Ⅲ,type Ⅲwas the most frequent LA type at L1-L4.In zone Ⅳ,type Ⅳ was the most frequent LA type at L3(n=44;88.0%),L4(n=42;93.3%),and L5(n=6;100%).Conclusions.The risk of LA injury during OLIF is the least when the cage is placed in zones Ⅱ and Ⅲ.Care is required during OLIF in zone Ⅳ of L3-L5.The fixation pin should be fixed on the upper edge of the lower vertebral body at L1-L2 and L2-L3,and on the lower edge of the upper vertebral body at L3-L4 and L4-L5.Part Ⅲ Comparison of the Biomechanical Performance of an Oblique Lateral Interbody Fusion Cage Among Models With Different Bone Densities:Finite Element AnalysisObjective:Decreased bone density is the key limiting factor for stand-alone OLIF.We compared the biomechanical performance of an oblique lateral interbody fusion(OLIF)cage among different bone density models.Methods:Four models—intact(M0),normal bone density with OLIF(M1),bone mass loss with OLIF(M2),and osteoporotic with OLIF(M3)-were created from 3-dimensional scans.Flexion,extension,and lateral bending moments(each 10 N·m)with a compressive preload of 500 N were applied on the superior surface of the L3 vertebra.Range of motion(ROM),peak stresses in the L4-5 cortical endplates,cage stress,and adjacent intervertebral disk stress were evaluated.Results:ROM during different physiological movements were similar to verification criteria reported by previous researchers.L4-5 ROM in M1,M2,and M3 decreased for all movements compared with M0.ROM in M3 decreased the most.Stress distribution in the cortical endplates increased up to 7.8%in M1 and M2,while in M3,stress increased up to 16.2%.Cage stress increases in M1 and M2 were within 8.1%,while in M3,stress increased up to 25.3%,especially for extension and right rotation.Compared with M0,L3-4 and L5-S1 intervertebral disk stress in all the other models increased with increasing bone quality,up to 69.8%and 98.3%,respectively.As loosening worsened,stress in the adjacent intervertebral disk also increasedConclusion:Stand-alone OLIF in M3 is not recommended because of the risk of cage subsidence.M1 and M2 OLIF had similar results for various lumbar spine movements.L4-L5 had reduced mobility in all directions,increased rigidity,limited cage displacement,increased resistance to deformation,and better stability;stand-alone OLIF improved biomechanical stability and can be used clinically.Part Ⅳ Clinical analysis of Stand-Alone oblique lateral lumbar interbody fusion in the treatment of degenerative lumbar diseasesObjective:To explore the feasibility,safety and efficacy of Stand-Alone OLIF in the treatment of lumbar degenerative diseases.Objective to evaluate the indirect decompression effect of Stand-Alone OLIF on lumbar spinal stenosis and the effect on lumbar balance in patients with ADS.Methods:The clinical and imaging data of 151 patients with lumbar degenerative diseases who underwent Stand-Alone OLIF operation in the Department of spine and orthopedics,yijishan hospital,Wannan Medical College from July 2017 to January 2020 were retrospectively studied.There were 77 cases of lumbar spinal stenosis and 30 cases of ADS.Gender,age,BMI,T-score,operation time,intraoperative blood loss,operation segment,length and height of fusion cage,hospital stay,postoperative hospital stay,and intraoperative and postoperative complications were recorded.VAS and ODI were used to evaluate the symptoms,signs and neurological function of all patients.Ll,DH,FH,FA,CSAC,ascd and SSCD were measured in all patients with lumbar spinal stenosis before and after operation;Cobb angle,Pt,PI,11,SS and DH were measured in all patients with ads before and after operation.Coronal and sagittal balance and bone graft fusion were evaluated at the last follow-up.Results:77 patients with lumbar spinal stenosis and 30 patients with ADS were included in this study.All patients were followed up for one year.There were 32 males and 45 females with an average age of 64.1 ± 10.8(45-85 years)and an average BMI of(24.15±2.52)kg/The average operation time was(77.25±14.25)min,the average intraoperative blood loss was(49.35±15.13)ml,the average hospital stay was(8.32±1.33)days,and the average postoperative hospital stay was(3.44±1.43)days.There were 97 surgical segments,57 single segment and 20 double segment.There were 23 L3-4 segments,73 L4-5 segments and 1 L5-S1 segment.The fusion height of 8 mm:10 mm:12 mm:14 mm was 1:24:55:17,and the fusion length of 45 mm:50 mm:55 mm was 9:60:28.There were 16 males and 14 females with an average age of 63.5±10.2(43-86 years)and an average BMI of 25.27±2.52 kg/The mean operative time was(80.45±14.15)min,the mean intraoperative blood loss was(55.25±17.23)ml,the mean hospital stay was(9.42±1.53)days,and the mean postoperative hospital stay was(3.84±1.63)days.There were 48 operative segments,12 single segment and 18 double segment.There were 1 at L2-3,17 at L3-4 and 30 at L4-5.The fusion height of 8 mm:10 mm:12 mm:14 mm was 3:17:24:4,and the fusion length of 45 mm:50 mm:55 mm was 3:35:10.All the indexes were improved after operation,except DH and FH,which were slightly lost in the last follow-up.There were 9 cases of intraoperative complications,23 cases of postoperative complications,1 case of intraoperative segmental artery injury,and 11 cases of postoperative fusion cage subsidence.Conclusion:Stand-Alone OLIF is safe,feasible and effective in the treatment of lumbar degenerative diseases.It provides a safe and effective minimally invasive spinal treatment,but its large sample,prospective long-term follow-up still need to be further studied. |
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