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BACKGROUND:The problem of intervertebral disc injury and degeneration has been studied in many ways.Many studies have shown that intervertebral disc injury and degeneration is driven by mechanical loading factors.However,the potential relationship between common phenotypes of intervertebral disc injury and degeneration and mechanical loading factors has been rarely summarized. OBJECTIVE:To summarize the types of common structural abnormalities exhibited by intervertebral disc injury and degeneration in the published literature,and sum up the potential links to the types of mechanical loading that lead to these structural abnormalities in in vitro and ex vivo experimental studies. METHODS:Using the terms"intervertebral disc failure,intervertebral disc injury,mechanical load,mechanical factor,load factor,biomechanics"as Chinese and English key words in PubMed,CNKI,and WanFang databases,articles related to intervertebral disc injury degeneration and mechanical load factors were retrieved.Literature screening was performed according to the inclusion and exclusion criteria,and 88 articles were finally included. RESULTS AND CONCLUSION:(1)Common structural abnormalities of intervertebral discs include decreased intervertebral disc height,disc bulge,osteophyte formation,annulus fibrosus tear,intervertebral disc herniation or disc prolapse,endplate damage,Schmorl nodes and intervertebral disc calcification.Intervertebral discs are susceptible to mechanical load types such as compression,bending,axial rotation,and compound loads.(2)The compressive load mainly causes the decrease of the proteoglycan content and the water-binding ability of the intervertebral disc,leading to the decrease or swelling of the intervertebral disc and further damage and degeneration of the intervertebral disc.In addition,the excessive compressive load causes greater damage to the endplate.(3)Bending load and axial rotation load damage the annulus fibrosus more than the endplate,and prolonged or repeated bending loads can cause tearing of the fibrous annulus and herniation or prolapse of the intervertebral disc,while pure axial rotation loads can induce less damage to the intervertebral disc and only cause the tear of the annulus fibrosus.(4)However,when different load types act in combination,it is more likely to result in high stress on the disc and a greater risk of disc injury.(5)Injury and degeneration of the intervertebral disc present progressive structural damage,and early prevention and protection are particularly important in clinical practice.Future tissue engineering research can start with early repair of the intervertebral disc.
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Objective@#To investigate the preliminary clinical efficacy of modified minimally invasive lateral interbody fusion in the anterior support and reconstruction for thoracolumbar fracture combined with intervertebral disc injury.@*Methods@#A retrospective case series study was conducted to analyze the clinical data of 14 patients with single-segment thoracolumbar fracture combined with intervertebral disc injury admitted to the Second Affiliated Hospital of Zhejiang University School of Medicine from December 2017 to May 2018. There were 12 males and two females, aged 22-56 years [(37.4±10.2)years]. The injured segments were at L1 in nine patients and L2 in five patients. Twelve patients had upper disc injury and two patients had lower disc injury. Before operation, American Spinal Injury Association (ASIA) classification was grade A in five patients, grade B in four, grade C in three, and grade D in two. All patients received modified minimally invasive lateral interbody fusion to reconstruct the stability of the anterior and middle columns of the spine one week after posterior short-segment fixation. The operation time, intraoperative bleeding, postoperative hospital stay and complications were recorded. Pain visual analogue scale (VAS) and ASIA nerve injury grading were used to evaluate the clinical efficacy. The Cobb angle changes of the operative segment and lumbar lordosis were compared before operation and during the last follow-up.@*Results@#The patients were followed up for 6-14 months[(12.1±3.6)months]. The operation time was 65-210 minutes [(138.9±39.4)minutes], and the intraoperative blood loss was 250-600 ml [(407.1±119.1)ml], respectively. The total postoperative length of stay ranged from 3 to 13 days [(7.8±2.5)days]. The incisions healed well at stage I in all patients. VAS for back pain and leg pain before operation were (6.3±2 .4)points and (4.1±1.3)points respectively. The final VAS for back pain and leg pain were (2.2±0.6)points and (2.3±0.8)points, which were significantly lower than the preoperative VAS (both P<0.01). At the last follow-up, there was one patient with grade A, two with grade B, five with grade C, one with grade D, and five with grade E. Postoperative CT showed that decompression was complete, implants were in good position and internal fixation was reliable. Preoperative Cobb angles of lumbar lordosis and the injury segment were (-7.8±3.9)° and (24.8±6.9)° respectively. The final Cobb angles of lumbar lordosis and the injury segment were (3.1±2.7)° and (30.7±9.6)°, which were significantly restored compared with preoperative values (both P<0.01). One patient had postoperative pain in the front thigh, and another patient had numbness in the front thigh, whose symptoms were alleviated after non-surgical treatment. No serious surgical complications such as quadriceps femoris and weakness, pleural tear, vascular injury, nerve root injury, sympathetic nerve injury, retroperitoneal hematoma and artificial vertebral body displacement occurred in these patients.@*Conclusions@#For anterior reconstruction of the thoracolumbar fracture with intervertebral disc injury, the modified minimally invasive lateral interbody fusion has the advantages of less invasive, less blood loss, shorter hospitalization time, low incidence of complications. Significant pain relief, neurological function improvement, and anterior and middle column reconstruction can be achieved postoperatively.
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Objective To investigate the preliminary clinical efficacy of modified minimally invasive lateral interbody fusion in the anterior support and reconstruction for thoracolumbar fracture combined with intervertebral disc injury. Methods A retrospective case series study was conducted to analyze the clinical data of 14 patients with single-segment thoracolumbar fracture combined with intervertebral disc injury admitted to the Second Affiliated Hospital of Zhejiang University School of Medicine from December 2017 to May 2018. There were 12 males and two females, aged 22-56 years [(37. 4 ± 10. 2)years]. The injured segments were at L1 in nine patients and L2 in five patients. Twelve patients had upper disc injury and two patients had lower disc injury. Before operation, American Spinal Injury Association ( ASIA) classification was grade A in five patients, grade B in four, grade C in three, and grade D in two. All patients received modified minimally invasive lateral interbody fusion to reconstruct the stability of the anterior and middle columns of the spine one week after posterior short-segment fixation. The operation time, intraoperative bleeding, postoperative hospital stay and complications were recorded. Pain visual analogue scale ( VAS) and ASIA nerve injury grading were used to evaluate the clinical efficacy. The Cobb angle changes of the operative segment and lumbar lordosis were compared before operation and during the last follow-up. Results The patients were followed up for 6-14 months[(12.1 ±3.6)months]. The operation time was 65-210 minutes [(138.9 ±39.4)minutes],and the intraoperative blood loss was 250-600 ml [(407. 1 ± 119. 1) ml], respectively. The total postoperative length of stay ranged from 3 to 13 days [(7. 8 ± 2. 5)days]. The incisions healed well at stage I in all patients. VAS for back pain and leg pain before operation were (6. 3 ± 2 . 4)points and (4. 1 ± 1. 3) points respectively. The final VAS for back pain and leg pain were (2. 2 ± 0. 6)points and (2. 3 ± 0. 8)points, which were significantly lower than the preoperative VAS (both P<0. 01). At the last follow-up, there was one patient with grade A, two with grade B, five with grade C, one with grade D, and five with grade E. Postoperative CT showed that decompression was complete, implants were in good position and internal fixation was reliable. Preoperative Cobb angles of lumbar lordosis and the injury segment were ( -7. 8 ± 3. 9)° and (24. 8 ± 6. 9)° respectively. The final Cobb angles of lumbar lordosis and the injury segment were (3. 1 ± 2. 7)° and (30. 7 ± 9. 6)°, which were significantly restored compared with preoperative values (both P<0. 01). One patient had postoperative pain in the front thigh, and another patient had numbness in the front thigh, whose symptoms were alleviated after non-surgical treatment. No serious surgical complications such as quadriceps femoris and weakness, pleural tear, vascular injury, nerve root injury, sympathetic nerve injury, retroperitoneal hematoma and artificial vertebral body displacement occurred in these patients. Conclusions For anterior reconstruction of the thoracolumbar fracture with intervertebral disc injury, the modified minimally invasive lateral interbody fusion has the advantages of less invasive, less blood loss, shorter hospitalization time, low incidence of complications. Significant pain relief, neurological function improvement, and anterior and middle column reconstruction can be achieved postoperatively.