[Imaging measurement for the posterior pars interarticularis screw fixation on axis].

OBJECTIVE: To explore the safety and feasibility of posterior pars interarticularis screw fixation on axis by CT measurement. METHODS: The CT data of 137 patients with complete upper cervical spine who underwent full cervical spine CT examination from January 2016 to December 2019 were collected, including 71 males and 66 females, aged from 22 to 65 years old with an average of (41.8±17.4) years old. Mimics 19.0 software was used to measure anatomical data related to the pars interarticularis screw, including the pars width, pars vertical length, pars vertical height, length of pars screw trajectory, upward inclination angle of pars screw trajectory. And the correlation between each index was analyzed. RESULTS: The axis pars has an average width of (9.05±1.63) mm, an average vertical length of (11.21±1.43) mm, and an average vertical height of (17.53±2.93) mm. The mean length of pars screw trajectory was(19.07±3.20) mm. Regarding to the length of pars screw trajectory, 94.53% of pars measured more than 14 mm, 82.12% of pars measured at 14-16 mm, 63.14% of pars measured at 16-18 mm, 39.78% of pars measured at 18-20 mm. The upward inclination angle of pars screw was 30°-68° with an average of (46.06±8.06) °. There was a highly positive correlation between the length of screw trajectory and upward inclination angle(r=0.965, P=0.000). The vertical length of pars was weakly positively correlated with length of screw trajectory and upward inclination angle(r=0.240, P=0.000;r=0.163, P=0.007). Pars width was moderately negative correlated with length of scrwe trajectory and upward inclination angle(r =-0.333, P=0.000;r=-0.380, P=0.000). CONCLUSION: The posterior pars interarticularis screw fixation is safe and reliable. It has a more wider applicability than pedicle screw fixation and can be used as an alternative to pedicle screws.

[Wiltse approach combined with contralateral transforaminal lumbar interbody fusion and conventional surgery for lumbar disc herniation:a case-control study].

OBJECTIVE: To compare the clinical effecty of Wiltse approach combined with contralateral transforaminal lumbar interbody fusion (TLIF) and traditional TLIF in the treatment of lumbar disc herniation and its affect on injury of multifidus muscle. METHODS: From June 2014 to September 2017, 90 patients with lumbar disc herniation combined with lumbar spine instability were divided into two groups (Wiltse approach group and traditional group) depend on the procedure of operation. Wiltse approach group was treated with Wiltse approach screw placement in one side combined with contralateral TLIF. There were 50 patients in Wiltse approach group, including 36 males and 14 females, aged 45 to 72 yearswith an average of (60.4± 3.1) years. The traditional group was treated with traditional TLIF operation. There were 40 patients in the traditional group, including 25 males and 15 females, aged 45 to 74 years with an average of (62.1±3.4) years. The operative time, intraoperative blood loss, accuracy of screw implantation, postoperative drainage volume and drainage tube removal time were recorded in two groups. Visual analogue scale (VAS) and Oswestry Disability Index (ODI)were observed before and 12 months after operation. All patients underwent CT examination preoperative and 12 months postoperative, and the CT values of bilateral multifidus muscle were measured. RESULTS: All the patients were followed up, 40 patients in traditional group were 12 to 18 months with an average of (15.3±4.3) months; and 50 patients in Wiltse approach group were 13 to 24 months with an average of (16.5± 4.1) months. There were no statistically significant differences in operative time and intraoperative blood loss between two groups (P>0.05). The accuracy of screw implantation in Wiltse approach group was higher than traditional group (P<0.05).There was no significant difference in preoperative VAS score and ODI between two groups, and 12 months after operation, VAS score and ODI in Wiltse approach group was significantly lower than traditional group (P <0.05). The postoperative drainage and drainage tube placement time in Wiltse approach group were lower than the traditional group(P<0.05). There was no statistically significant difference in CT value of multifidus muscle before operation between two groups (P>0.05), while there was statistically significant difference after operation (P<0.05). Postoperative CT values of multifidus muscles on decompression and non-decompression side were obviously reduced in traditional group (P<0.05). The CT value of the multifidus muscle on the decompression side of the Wiltse approach group was significantly lower than that before operation(P<0.05), and there was no significant difference before and after the operation on the non-decompression side (P>0.05). CONCLUSION: Compared with traditional surgical procedures, the Wiltse approach nail placement combined with contralateral TLIF has the advantage of accurate nail placement, reducing multifidus muscle damage, and reducing the incidence of postoperative intractable low back pain.

[Case control study of unilateral and bilateral intervertebral space release in the treatment of lower lumbar spondylolisthesis].

OBJECTIVE: To analyze the clinical efficacy of unilateral and bilateral intervertebral space release in the treatment of lower lumbar spondylolisthesis. METHODS: The clinical data of 41 patients with lumbar spondylolisthesis treated by surgery from October 2012 and May 2016 were retrospcetive analyzed. The patients were divided into two groups, 18 cases were enrolled in unilateral intervertebral release group, there were 7 males and 11 females, aged from 47 to 75 years old with an average of (59.3±6.4) years; according to Meyerding classification, 9 cases of I degree, 7 cases of II degree, 2 cases of III degree. And 23 cases were bilateral release group, there were 11 males and 12 females, aged from 51 to 76 years old with an average of (58.2±5.7) years; according to Meyerding classification, 11 cases of I degree, 10 cases of II degree, 2 cases of III degree. The operation time, intraoperative blood loss, bone graft fusion rate of the patients were recorded in the patients. Pre- and post-operative back and leg pain were evaluated by visual analogue scale (VAS) between two groups. The slip rate, slip angle, posterior height of intervertebral space, height of intervertebral foramen, distance of anterior and posterior displacement of vertex of intervertebral foramen were measured on X-ray and CT. And the above radiographic data were analyzed by intra-group or inter-group. RESULTS: All the patients were followed up from 9 to 24 months with an average of 12 months. The entire 41 patient obtained bone fusion at 12 months after operation. There was no statistical significance in VAS at 12 months after operation, intraoperative blood loss and operation time between two groups(P>0.05). There were statistical significance in sliding angle, posterior height of intervertebral space, height of intervertebral foramen, distance of anterior and posterior displacement of vertex of intervertebral foramen of all patients before and after operation(P<0.05). There was no statistical significance in spondylolisthesis rate in unilateral release group between pre- and post-operative(P>0.05), but there was significant difference in bilateral release group. There was statistical significance in postoperative slip angle, posterior height of intervertebral space, distance of anterior and posterior displacement of vertex of intervertebral foramen between two groups(P=0.001, 0.045, 0.001). The height of intervertebral foramen increased and the slippage rate decreased in both groups after operation, but there was no significant difference between two groups(P=0.248). CONCLUSIONS: Unilateral and bilateral intervertebral space release for the treatment of lumbar spondylolisthesis can obviously reduce the rate of spondylolisthesis, restore foraminal height and achieve better clinical efficacy. Bilateral release group can better restore the slip angle, increase posterior height of intervertebral space, reduce the distance of anterior and posterior displacement of vertex of intervertebral foramen. Especially for grade II or above degree of slippage is more appropriate.

[Effect of reduction on spino-pelvic parameters in treating high-grade lumbar spondylolisthesis].

OBJECTIVE: To explore the effect of reduction on spino-pelvic balance in treating high-grade lumbar spondylolisthesis. METHODS: From Augest 2008 to Augest 2011, the data of 16 patients with high-grade lumbar spodylolisthesis (Meyerding grade III or more than grade III) underwent reduction treatment through posterior approach were retrospectively analyzed. There were 9 males and 7 females, aged from 24 to 65 years old with an average of 44 years. Preoperative, postoperative at 2 weeks and final follow-up, spino-pelvic parameters of all patients were measured and compared by total legth lateral X-rays, and spino-pelvic parameters included sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL) and sagittal vertical axis (SVA); the informations of intervertebral bone fusion was observed by CT and postoperative complications were recorded; clinical effects were assessed according to clinical Oswestry score (CODI). RESULTS: All patients were followed up from 12 to 24 months with an average of 18 months. Four cases reduced anatomically, 8 cases reduced to grade I .4 cases reduced to grade II. There was statistically significant differences in sacral slope (SS), pelvic tilt (PT), lumbar lordosis angle (LL) and sagittal vertical axis (SVA) between before operation and two weeks after operation (P < 0.05), while pelvic incidence (PI) no statistically significant differences was found between before operation and two weeks after operation (P > 0.05). There was no statistically significant differences in SS, PT, LL, SVA, PI between two weeks after operation and final follow-up (P > 0.05). CODI had decreased from preoperative 36.6 ± 4.2 to 14.7 ± 4.0 at final follow-up (P < 0.05). One year after operation, all patients obtained bone fusion and can find the union of bone trabeculae by three-dimensional reconstruction CT. Three cases occurred transient nerve root pain, and recovered after medicinal treatment. No infection and internal fixation loosening and breakage were found. CONCLUSION: Surgical reduction for high-grade lumbar spondylolisthesis can improve spino-pelvic balance and acquire satisfactory outcomes.

[Posterior reduction and interbody fusion for the treatment of thoracolumbar fractures and dislocations].

OBJECTIVE: To explore efficacy of posterior reduction and interbody fusion in treating thoracolumbar fractures and dislocations. METHODS: From August 2004 to May 2009, 24 patients (18 males and 6 females with an average of 38.2 years, ranged 24 to 56 years old) were treated. Among them, 14 cases were by traffic accident,6 cases were falling down, 2 cases were heavy hit, 2 cases were transverse crush. According to AO classification, 12 cases were type B1, 5 cases B2, 2 cases B3,3 cases C1, 2 cases C2. One cases in T(10,11), 2 cases in T(11,12), 5 cases in T12L1, 8 cases in L(1,2), 2 cases in L(2,3), 4 cases in L(3,4), 2 cases in L4/5. Acoording to Frankle classification,5 cases in grade A, 9 cases in grade B, 8 cases in grade C and 2 cases in grade D. The reduction, graft healing and recovery of nervous function were followed up. RESULTS: All patients were followed up from 8 to 33 months with an average of 16 months. The operation time was for 3.0 to 5.8 hours, meaned 3.7 h, and mean blood loss was 860 ml (ranged, 500 to 1800 ml). Cobb angle improved from preoperative (32.6 +/- 3.7) degrees to postoperative (13.7 +/- 2.4) degrees. The anterior high of fractured vertebrae increased from preoperative (41.0 +/- 11.6)% to postoperative (87.6 +/- 2.3)% .Three cases of 5 cases with Frankle A were not recovery, 1 case changed to grade B, 1 case changed to grade C; Five cases of 9 cases with Frankle B were changed to grade C, 3 cases to grade D, 1 case changed to grade E; Five cases of 8 cases with Frankle C were changed to Grade D, 3 cases to Grade E; Two cases with Frankle D were recoved to normal. Planting bone surface got bone fusion, and no internal fixation lossen, dislocation occurred. CONCLUSION: Posterior reduction and rigid interbody fusion for the treatment of thoracolumbar fractures and dislocations can receive satisfactory fusion based on recovering normal spinal sequence

Short-term clinical observation of the Dynesys neutralization system for the treatment of degenerative disease of the lumbar vertebrae.

OBJECTIVE: To explore the safety and short-term efficacy of the posterior approach of the Dynesys dynamic neutralization system for degenerative disease of the lumbar vertebrae. METHODS: From March 2008 to March 2010, 32 cases of degenerative lumbar vertebral disease, 19 men and 13 women, (mean age 58 ± 5.2, range, 43-78 years), were treated with posterior laminectomy and Dynesys internal fixation. All patients had a history of over 3 months waist or leg pain that had not been relieved by conservative treatment. There were 10 cases of single lumbar intervertebral disc protrusion, 14 of degenerative lumbar spinal stenosis, 5 of degenerative lumbar isthmic spondylolisthesis, and 3 of recurrent lumbar disc protrusion after surgery. A visual analogue score (VAS) was used for pain assessment, and the Oswestry disability index (ODI) for functional evaluation of clinical outcomes. RESULTS: All patients were followed up for 6-23 months (mean, 16.4 ± 5.5 months). Forty-one segments in 32 patients were stabilized; 23 cases (71.9%) underwent single-segmental stabilization, and 9 (28.1%) two-segmental stabilization. VAS of leg pain, root and low back pain was significantly improved postoperatively. The ODI improved from preoperative 69% ± 12.6% to postoperative 28% ± 15.7% (P < 0.001). On the stabilized segment and adjacent segments above and below, the range of movement showed no statistical difference; no loosening of screws, cord and polyester spacer occurred. CONCLUSION: The Dynesys dynamic neutralization system combined with decompression can achieve satisfactory short-term clinical results in lumbar degenerative disease. This procedure system not only reduces back and leg pain, but also preserves the mobility of fixed segments, minimizes tissue injury and avoids taking bone for spinal fusion.

[Anatomic comparison between spinous process screws and pedicle screws techniques of the second cervical vertebar].

OBJECTIVE: To compare anatomic difference between spinous process screws and pedicle screws techniques of the second cervical vertebra. METHODS: Ten human cadaveric of cervical spine (5 male, 5 female) were harvested and had no gross deformities such as scoliosis and/or kyphosis were found in the study. The average age of the subjects was 60.5 years. The specimens were placed in the prone position. Posterior cervical exposure was attained by dissecting all soft tissue off the posterior aspect of the second cervical vertebra. After clear exposure of the lateral mass,the spinous process screw and pedicle screw insertion techniques were performed in this study. Each technique involved ten specimens and 10 screws inserted into C2 bilaterally. The one side of C2 was randomly selected for the spinous process screw and the other side was designate for the pedicle screw. This point then was drilled with a 3 mm drill, and followed by placement of a 4.0 mm cortical screw. The starting point for spinous process screw insertion was located at the junction of the lamina and the spinous process and the direction of the screw was about 0 degrees caudally in the sagittal plane and about O0 medially in the axial plane. The starting point of pedicle screw should be the midpoint of the base of inferior articular facet of the axis. The drilling angle was 15 degrees to 20 degrees in the superior direction and 30 degrees in the medial direction. After screw placement, all the specimens were CT scaned. On the CT scan,the length of the spinous process screw and pedicle screw trajectory were measured. Results were recorded for each screw that violated impinged of the pedicle, spinal canal and transverse process foramen. RESULTS: All the C2 spinous process screws were successfully placed, without impingement the spinal cord, the vertebral artery and the breakage of the spinous process. There was one pedicle screw breaking the pedicle into the vertebral artery foramen. The trajectory length for the spinous process screws were (21.4 +/- 1.4) mm,compared with the pedicle screws (23.7 +/- 1.0) mm. But there was no significant differences between spinous process screws and pedicle screws techniques (t = -4.387, P > 0.05). CONCLUSION: The C2 spinous process screw fixation has the anatomic feasibility and is easier to perform than pedicle screw fixation.

[Clinical study of posterior transarticular fixation with rod-screw in the lower cervical vertebrae].

OBJECTIVE: To explore the effects of posterior transarticular fixation with rod-screw in treating fracture and dislocation, spinal stenosis of lower cervical vertebrae. METHODS: From July 2005 to July 2009,11 patients with cervical fracture and dislocation and 9 with spinal stenosis of lower cervical vertebrae underwent operation with transarticular fixation with rod-screw (Vertex system). There were 16 cases male and 4 cases female, ranging in age from 29 to 76 years with an average of 51 years. All patients underwent decompression,internal fixation and fusion through posterior approach (combined with anterior approach in 3 cases). The method of insertion of screw: the starting point located in medial 1 mm of the midpoint of the lateral mass, angle in sagittal plane was 15 degrees-20 degrees of caudal clinism and in coronal plane was 35 degrees-40 degrees of external clinism. The position of screws, the cervical array, bone graft and fusion were observed by X-ray films. RESULTS: A total of 88 transarticular screws were successfully inserted, 10 screws located in C3,4, 20 in C4,5, 32 in C5,6, 26 in C6,7. There were no complications related to screw insertion, such as injury of the vertebral artery, nerve roots and the spine cord. All patients obtained bone fusion without internal fixation breaking. The improvement rate of JOA was 55.8% at the 1st week after operation, 5 cases got excellent results, 7 good, 7 fair, 1 poor; the improvement rate of JOA was 74.5%, at the 3rd month after operation, 6 cases got excellent results, 8 good, 6 fair. There was significant difference in the JOA between before operation and at the 3rd month after operation. CONCLUSION: The transarticular screw fixation with rod-screw in the lower cervical spine is an effective fixation, which has advantages of rigid stability, convenience to perform, and can reduce operative risk in initial application, but the long-term follow-up is very necessary.

[An anatomic study of posterior C(2) spinous process laminar screw fixation].

OBJECTIVES: To explore the feasibility and the technical parameters in posterior C2 spinous process laminar screw fixation, and discuss the clinic significance of C2 spinous process laminar screws. METHODS: Twenty cervical cadaveric spines of C2 were dissected, with care taken to expose the lamina and spinous process. After the entrance point of spinous process screw were determined, posterior C2 spinous process laminar screw implantation was performed under visual control. On the morphologic CT scan, the angle and length of the spinous process laminar screw trajectory and the distance between the tip of the screw and the spinal cord and the vertebral artery were measured. RESULTS: The C2 spinous process laminar screws were successfully placed, without impingement of the spinal cord and the vertebral artery. There were little differences between superior and inferior screws in the angle, trajectory length and the distance between the tip of the screw and the spinal cord and the vertebral artery, but without significance (P > 0.05). The placed angles of the screws were 76.8° ± 10.6° in the axial plane. The distance between the tip of the screw and the spinal cord and the vertebral artery was (5.3 ± 1.6) mm and (17.4 ± 3.7) mm respectively. The trajectory length was (23.1 ± 3.2) mm. CONCLUSIONS: Posterior C2 spinous process laminar screw fixation is feasible. C2 spinous process laminar screw fixation affords an alternative to standard screw placement for plate fixation and cervical stabilization.

[Clinical observation of mid-stage complications after cervical disc replacement].

OBJECTIVE: To summarize the therapeutic experience of Bryan prosthetic cervical disc replacement at the 3rd years after operation and to analyze the clinical effect, incidence rate of heterotopic ossification, conditions of prosthetic fusion in order to investigate the countermeasures. METHODS: From December 2005 to December 2008, 54 patients with cervical syndrome (34 males and 20 females, the age was from 39 to 69 years with an average of 50.5) were treated with single level Bryan prosthetic cervical disc replacement. The patients were followed for 24-36 months with an average of 30 months. The symptoms and nerve function were evaluated according to JOA and Odom's scoring. The anterior-posterior and lateral cervical X-ray films were also taken regularly every three months for the observation of heterotopic ossification and prosthetic fusion. Meanwhile, the X-ray films of the forward bending, extending, left and right lateriflection were taken before operation and at the 1st years after operation for the measurement of the stability and rang (ROM) of replaced levels. RESULTS: The pain symptom and neurological function of all 54 patients were improved obviously. JOA score increased with an average of 76.1%, and ROM of replaced levels also improved obviously. The incidence rate of heterotopic ossification and prosthetic fusion went up year by year, 3.7% (2/54) for the first year, 16.7% (9/54) for the second year and 22.2% (12/54) for the nearly third year. CONCLUSION: Bryan prosthetic cervical disc replacement has better mid-stage results than conventional methods. Modified surgical methods and early rehabilitation exercise may reduce the relatively high incidence rate of heterotopic ossification and prosthetic fusion.

[Anatomical considerations for the placement of C2 spinous process screws].

OBJECTIVES: To quantitatively anatomically evaluate the C2 spinous process, analyze the anatomical feasibility of the C2 spinous process screws and its clinical significance. METHODS: To dissect and evaluate 30 cervical cadaveric spines of C2 which were taken to expose the lamina and spinous process. Anatomic quantitative evaluation of the C2 spinous process included its height and width. Twenty cervical cadaveric spines of C2 were chosen to the study of the placement of the C2 spinous process screws. The starting point for the C2 spinous process screw insertion was located at the base of the spinous process. After the entrance point of spinous process screws was determined, posterior C2 spinous process screw implantation was performed bilaterally under direct visualization. On the morphologic CT scan, the width of C2 spinous process base, the angle and length of the spinous process screw trajectory, and the distance between the tip of the screw and the spinal cord and the vertebral artery were measured. RESULTS: The average height and width of the C2 spinous process were (12.90 ± 1.30) mm and (18.86 ± 1.17) mm respectively. The C2 spinous process screws were successfully placed without impingement the spinal cord or the vertebral artery and the breakage of the spinous process. On the CT scan, the average width of the base of C2 spinous process was (20.7 ± 1.3) mm. The placed angles of the screws were 1.8° ± 1.0° in the axial plane. The distance between the tip of the screw and the spinal cord or the vertebral artery was (8.3 ± 2.6) mm and (20.2 ± 3.1) mm respectively. There were little differences between superior and inferior screws in the angle, the distance between the tip of the screw and the spinal cord or the vertebral artery, but without significance (P > 0.05). The average trajectory length of the C2 spinous process screws was (19.7 ± 1.1) mm. The average trajectory length of the superior spinous process screws was shorter than that of inferior spinous process screws, with great differences (t = 3.566, P < 0.01). CONCLUSIONS: There is the anatomic feasibility of the C2 spinous process screw fixation which may afford an alternative to standard screw placement for axis fixation. The biomechanical study for the C2 spinous process screw is also necessary.

[Quantitative anatomic study on atlas and designation of bionic plating of anterior arch of atlas].

OBJECTIVE: To observe and measure specimen of Chinese atlas to obtain morphological parameter, providing anatomic data for designing bionic plating of anterior arch of atlas. METHODS: The anatomic parameters of 48 sets of fresh Chinese adults' atlas specimens were measured with a electric digital caliper and a goniometer, including width of anterior arch of atlas (AW), thickness of atlas at the junction of anterior arch and lateral mass (AD), thickness and height of anterior tubercle of atlas (AT and AH), middle height, length and width of the lateral mass (MHL, L and LW), the extraversion angle of lateral mass of atlas (alpha degrees) and so on. The data were statistically analyzed in order to ascertain the range of morphological parameter of bionic plating of anterior arch of atlas. RESULTS: The measurement results showed that AW was (20.68 +/- 1.38) mm, AD was (3.86 +/- 1.42) mm, AT was (8.65 +/- 1.88) mm, AH was (10.36 +/- 1.49) mm, MHL was (12.82 +/- 1.76) mm, LW was (12.86 +/- 1.63) mm, the extraversion angle of lateral mass of atlas (alpha degrees) was (13.84 +/- 1.73) degrees. The plating was composed of connecting plate of anterior arch of atlas and fixing plate of atlas lateral mass in bilateral. CONCLUSION: The designation of bionic plating of anterior arch of atlas is feasible on morphology. The bionic plating of anterior arch of atlas can not only rebuild the stability of atlas, but also reserve the rotation function between atlas and axis. The plating could be used for patient suffering from instability of upper cervical because of atlas affection.