The Imaging Characteristics Of Rigid Post-traumatic Thoracolumbar Kyphosis (RPTK)

OBJECTIVE: To observe the imaging characteristics of rigid post-traumatic thoracolumbar kyphosis(RPTK)and discuss its clinical value.METHODS: Preoperative clinical data and imaging images were collected from patients with RPTK who received diagnosis and treatment in the Department of Spine Surgery of the Affiliated Hospital of Southwest Medical University between January 2014 and October 2022;loss of height of the posterior wall of the injured vertebrae measured by lateral X-ray of the thoracolumbar spine less than 2 mm was defined as the compression fracture group(CPF),and greater than 2 mm The group was defined as burst fracture(BFT).The differences in baseline data such as age,sex,fracture etiology,disease duration,VAS score of low back pain,ODI index,ASIA classification of spinal cord injury were compared between the CPF and BFT groups;the characteristics of endplate injury,anterior vertebral bridge formation,articular eminence fusion,anterior and posterior wall height loss of injured vertebrae,Cobb angle,wedge angle of vertebral body,and canal encroachment rate were observed,measured and compared between the CPF and BFT groups.RESULTS: 1.A total of 86 patients with RPTK were included in this study,54cases(62.8%)in the CPF group and 32 cases(37.2%)in the BFT group.In addition,1 case in the CPF group and 2 cases in the BFT group with a total of 3cases combined with a 10-25° lateral lordosis were excluded.31 cases in the CPF group were male and 23 cases in the BFT group were female.Age was 54.6±4.7 years.The duration of disease was 12.4±6.5 years.Low back pain VAS score was 6.0±0.7.ODI index was 53.5±7.2.6 cases of ASIA grade D and48 cases of grade E.There were 19 males and 13 females in the BFT group.Age was 51.4±7.6 years.Duration of disease was 5.7±4.8 years.There was no statistically significant difference between the CPF group and the BFT group in terms of gender,age,cause,low back pain VAS score and ODI index(P > 0.05).The incidence of spinal nerve injury was 11.1%(6/54)in the CPF group and28.1%(9/32)in the BFT group,and the incidence of spinal nerve injury was significantly higher in the BFT group than in the CPF group(2=6.25,P=0.01).This indicates that patients with RPTK due to violent fracture have a shorter duration of disease and a higher rate of spinal cord nerve injury.2.There were78 cases(90.7%)of combined endplate injury and 8 cases(9.3%)of no endplate injury.There were 50 cases of upper endplate injury(58.1%),13 cases of lower endplate injury(15.1%),and 15 cases of both upper and lower endplate injury(17.4%).There were 12 cases(15.4%)of endplate type I injury,46 cases(59%)of type II injury,and 20 cases(25.6%)of type III injury.46cases(85.2%)of endplate injury in the CPF group,including 35 cases(64.8%)of upper endplate injury,7 cases(12.7%)of lower endplate injury,and 4 cases(7.4%)of both upper and lower endplate injury;12 cases(26.1%)of endplate type I injury,and Type II injury was present in 27 cases(58.7%),and type III injury was observed in 7 cases(15.2%).32 cases in the BFT group had endplate injury(100%),including 15 cases of upper endplate injury(46.8%),6 cases of lower endplate injury(18.7%),and 11 cases of upper and lower endplate injury (34.5%);0 cases of endplate type I injury(0%),19 cases of type II injury(59.4%),and 13 cases of type III injury(40.6%).There was a significant difference in the type and location of endplate injury between the CPF and BFT groups(P < 0.05),with the CPF group mainly located in the upper endplate and mostly a single endplate injury,and the BFT group mainly located in the upper endplate,but the incidence of both upper and lower endplate injury was higher.The incidence and extent of endplate injury in the BFT group were greater than those in the CPF group.3.A total of 29 cases(33.7%)of anterior vertebral bridges were formed in this group,and 57 cases(66.3%)of anterior vertebral bridges were not formed.The prevertebral bridge formation rate in the CPF group was 44.4%(24/54),with 17 cases(31.5%)located in the anterior superior border of the injured vertebra and the anterior inferior border of the superior vertebra,3 cases(5.5%)in the anterior inferior border of the injured vertebra and the anterior superior border of the inferior vertebra,and 4 cases(7.4%)in the anterior border of the adjacent superior and inferior vertebra.There were 3cases(9.3%)in the anterior intervertebral space between the anterior superior border of the injured vertebra and the anterior inferior border of the superior vertebra,2 cases(6.2%)in the anterior inferior border of the injured vertebra and the anterior superior border of the inferior vertebra,and 0 cases in the anterior intervertebral space of the adjacent superior and inferior vertebra;the rate of anterior vertebral bridge formation was significantly greater in the CPF group than in the BFT group(2=8.31,P=0.04),indicating that anterior vertebral bridges were most common in the CPF group,and the formation sites were mainly The formation sites were mainly located at the anterior superior edge of the injured vertebra and the anterior inferior edge of the superior vertebra in the anterior intervertebral space.4.In this study,61 cases of articular fusion occurred,with a fusion rate of 70.9%(61/86)and 29.1%(25/86)of non-union of articular processes.In the CPF group,there were 44 cases of articular fusion(25 cases of Tromme II fusion and 19 cases of Tromme III fusion),which were located in 27 cases(50%)of superior joint synapse and superior inferior vertebral synapse,7 cases(13%)of inferior joint synapse and inferior supravertebral synapse,and 10 cases(18.5%)of superior and inferior supravertebral synapse fusion in the injured spine.In the BFT group,there were17 cases of fusion(9 cases of Tromme II fusion and 8 cases of III fusion),12cases(37.5%)were located in the supraspinal synapse with the superior inferior synapse,1 case(3.1%)was located in the inferior synapse with the inferior supraspinal synapse,and 4 cases(12.5%)were located in the superior inferior synapse and inferior supraspinal synapse.The fusion rate in the CPF group was significantly greater than that in the BFT group(2=10.55,P=0.004),and the fusion sites in the two groups were mainly located in the superior and inferior synapses of the injured vertebrae.5.The mean Cobb angle in the CPF group ranged from 28 to 55°,35.0±9.4°,and the mean Cobb angle in the BFT group ranged from 22 to 38°,26.5±6.4°.The local Cobb angle in the CPF group was significantly greater than that of the BFT group,and the difference was statistically significant(P=0.00).The vertebral wedge angle was 21.4±5.3° in the CPF group and 16.5±7.2° in the BFT group,and the wedge angle of the injured vertebra was significantly greater in the CPF group than in the BFT group,with a statistically significant difference(P<0.05).There was a statistically significant difference(P=0.00).12.1±2.9mm of anterior wall height loss in the CPF group and 10.1±3.2mm in the BFT group,both groups had significant loss of anterior wall height,and the CPF group had greater anterior wall height loss than the BFT group,a statistically significant difference(P<0.05).There were 23 cases(71.9%)with spinal canal encroachment rate of23.2±6.3%.This indicates that the CPF group had more severe injury wedge deformation and more serious posterior convexity deformity,and the BFT group had obvious canal encroachment due to RPTK.6.The group had 45 cases(52.3%)of articular fusion without anterior vertebral bridge,16 cases(18.6%)of both articular fusion and anterior vertebral bridge,13 cases(15.1%)of formation of anterior vertebral bridge without articular fusion,12 cases(14%)of no articular fusion and anterior vertebral bridge,indicating that imaging observable intervertebral joint stiffness in RPTK accounted for 86% of the cases,and articular eminence fusion was the main site of stiffness in RPTK.Conclusions: 1.RPTK can occur in patients with compression fractures,burst fractures,or fracture dislocations with three-column injuries.2.RPTK due to brust fracture is usually associated with less posterior convexity deformity,more endplate injury,higher canal encroachment rate and spinal nerve injury;RPTK due to compression fracture has greater posterior convexity Cobb angle,more severe injury wedge deformation and loss of anterior column height.3.86% incidence of articular fusion was observed in the intervertebral joint stiffness of RPTK,and articular fusion was the main site of stiffness in RPTK in 12 cases(14%).Conclusions: 4.Different fracture types produce different causes of chronic low back pain and spinal nerve damage,and the Cobb angle size is not a determining criterion for surgical treatment of RPTK.