Biomechanical effects of posterior lumbar interbody fusion with vertical placement of pedicle screws compared to traditional placement.

BACKGROUND: The pedicle screw technique is widely employed for vertebral body fixation in the treatment of spinal disorders. However, traditional screw placement methods require the dissection of paraspinal muscles and the insertion of pedicle screws at specific transverse section angles (TSA). Larger TSA angles require more force to pull the muscle tissue, which can increase the risk of surgical trauma and ischemic injury to the lumbar muscles. AIM: To study the feasibility of zero-degree TSA vertical pedicle screw technique in the lumbosacral segment. METHODS: Finite element models of vertebral bodies and pedicle screw-rod systems were established for the L4-S1 spinal segments. A standard axial load of 500 N and a rotational torque of 10 N/m were applied. Simulated screw pull-out experiment was conducted to observe pedicle screw resistance to pull-out, maximum stress, load-displacement ratio, maximum stress in vertebral bodies, load-displacement ratio in vertebral bodies, and the stress distribution in pedicle screws and vertebral bodies. Differences between the 0-degree and 17-degree TSA were compared. RESULTS: At 0-degree TSA, the screw pull-out force decreased by 11.35% compared to that at 17-degree TSA (P < 0.05). At 0-degree and 17-degree TSA, the stress range in the screw-rod system was 335.1-657.5 MPa and 242.8-648.5 MPa, separately, which were below the fracture threshold for the screw-rod system (924 MPa). At 0-degree and 17-degree TSA, the stress range in the vertebral bodies was 68.45-78.91 MPa and 39.08-72.73 MPa, separately, which were below the typical bone yield stress range for vertebral bodies (110-125 MPa). At 0-degree TSA, the load-displacement ratio for the vertebral bodies and pedicle screws was slightly lower compared to that at 17-degree TSA, indicating slightly lower stability (P < 0.05). CONCLUSION: The safety and stability of 0-degree TSA are slightly lower, but the risks of screw-rod system fracture, vertebral body fracture, and rupture are within acceptable limits.

[Treatment of acute unstable proximal clavicular fracture with hook plate of sternoclavicular joint].

OBJECTIVE: To investigate clinical effect of sternoclavicular hook plate in treating acute proximal clavicle fracture. METHODS: The clinical of 12 patients with acute unstable proximal clavicle fracture from June 2016 to June 2019 were retrospectively analyzed. There were 8 males and 4 females, aged from 46 to 63 years old. Ten patients caused by car accident and 2 patients caused by high falling. All patients had multiple injuries;the time from injury to surgery ranged from 2 to 14 d. All patients were treated with domestic sternoclavicular joint hook plate. The operative time ranged from 40 to 115 min. The intraoperative bleeding volume ranged from 30 to 110 ml, follow-up time ranged from 10 to 36 months, the fracture healing time ranged from 8 to 18 weeks. At the latest follow-up, the efficacy was evaluated by using shoulder joint function score (Rockwood score). RESULTS: All 12 patients were followed up, with no obvious pain at the latest follow-up. The rockwood scores of the affected shoulder ranged from 13 to 14, and the healthy shoulder ranged from 14 to 15. CONCLUSION: The sternocleidoclavicular joint plate is fixed with preformed plate. The cantilever is designed to retain the motion of the sternoclavicular joint. It's safe and simple, avoid, the injury of important organs during operation, and has a good prognosis. It is an ideal fixation method for the treatment of proximal clavicle fracture.

[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.

[Effect of posterior osteotomy on the sagittal parameters of the spinopelvis in patients with lumbar degenerative kyphosis].

OBJECTIVE: To investigate the influence of posterior osteotomy on spinopelvic parameters in lumbar degenerative kyphosis (LDK) patients. METHODS: The clinical data of 21 patients with lumbar degenerative kyphosis who underwent osteotomy from January 2012 to December 2015 were retrospectively analyzed. There were 5 males and 16 females, aged from 55 to 76 years with an average of (66.24±5.13) years. All patients had taken preoperative and postoperative full length spinal X-ray, analyzing the spinopelvic parameters as thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). RESULTS: All operations were successful, the average operative time was 190 min (160 to 220 min) and intraoperative blood loss was 1 000 ml (800 to 1900 ml). Parameters of the patients between preoperative and period 1-year follow-up were as follows : preoperative TK increased from (31.67±21.13) ° to (34.67±11.60) °, LL corrected from (4.76±3.17) ° to (37.41±6.28) °, PT reduced from (33.94±5.01) ° to (20.12±5.36) °, and SS improved from (18.47±2.60) ° to (31.71±4.30) °, SVA restored from (13.24±3.60) cm to (2.82±1.33) cm. There were significant differences of spinopelvic parameters between preoperation and postoperation (P<0.05). CONCLUSION: Posterior osteotomy can effectively reconstruct the sagittal balance of spinopelvis in patients with lumbar degenerative kyphosis. The recovery of lumbar lordosis and sacral slope is closely related to the reconstruction of sagittal balance.

[Digital modeling and analysis of the applicability of backward rotation method in lumbar kyphoplasty with unilateral puncture].

OBJECTIVE: The 3D model of lumbar spine was established by using Mimics software. To observe the applicability and needling parameters of lumbar vertebral kyphoplasty with unilateral puncture by backward rotation method using simulated puncture. METHODS: Twenty-four patients (12 males and 12 females) with osteoporotic thoracic fracture in the first time and no signs of lumbar misalignment and bone destruction were scanned by spiral CT on the lumbar spine. The original DICOM file was modeled in 3D with Mimics software, and the vertebral bodies were separated. After being imported into 3-matic software, the posterior wall of the vertebral body was restrained for standardized measurement. A sketch perpendicular to the mid-section of the pedicle and the posterior wall of the vertebral body was drawn. The simulated puncture was performed on the sketch. The angle and distance parameters of the range of motion of the puncture needle were recorded, and the puncture needle was recorded at the top. The crossing points of the anterior, middle and posterior zones of the tangential line of the vertebral body were located at the high extraversion angle, and the results were compared and analyzed. RESULTS: All the data in the left and right sides had no significantly differences(P>0.05). Data of different segments in different gender were significantly differences(P<0.05). The maximal extraversion angle in lumbar spine increased gradually from (33.41±1.31) degree to (56.53±4.71) degree in males, as same as in females from(28.58±2.55) to (53.86±2.68) degree. There was no crossing point in area A, 3.3% of males and 26.67% of females in area B, rest in area C. The distribution areas on gender showed statistically significance (P<0.05). CONCLUSIONS: Backward rotation method can theoretically meet the requirements of puncture point for vertebral compression fracture, especially for males and lower lumbar spine. The determination of the maximum inclination angle is of guiding significance to the backward rotation method.

[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.

[Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia for lumbar disc herniation in elder with systemic diseases].

OBJECTIVE: To explore the clinical effect of percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia for lumbar disc herniation in elder with systemic diseases. METHODS: The clinical data of 44 elder patients with lumbar disc herniation and systemic diseases treated from June 2013 to June 2017 were retrospectively analyzed. Including 26 males and 18 females, aged 70 to 86 years old with an average of(77.5±3.5) years, course of disease was 3 weeks to 6 months. Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia was performed in the patients. Postoperative straight leg-raising degree change and Nakai criteria were used to evaluate the operative effect. Visual analogue scale(VAS) and JOA scoring system were used to compare the symptom improvement between preoperative and postoperative. RESULTS: No serious complications occurred during and after the operation, and the coexisting medical diseases were not aggravated. All patients safely survived the perioperative period. All the 44 cases were followed up from 6 to 30 months with an average of 20 months. Postoperative straight leg raising angle was obviously improved. At final follow-up, according to Nakai standard, 41 cases got excellent results, 3 good. VAS scores were significantly decreased and JOA scores were significantly increased in final follow-up(P<0.01). CONCLUSIONS: Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia is a safe, effective, less invasive technique for the treatment of lumbar disc herniation in elder with systemic diseases. Multidisciplinary collaboration and perioperative well controlled disease are essential for early rehabilitation of such patients.

[Research progress on pathogenesis of temporary osteoporosis in hip].

Transient osteoporosis of the hip(TOH) is classified as a type of bone marrow edema syndrome. TOH is lack of previous study and there is still controversy about his pathogenesis. In recent years, with the development of multi-discipline, such as imaging, pathology, molecular biology, the study has found that the pathological mechanism is complex, while its mechanism is still not clear, which need further research. This paper summarizes the research progress on the pathogenesis of TOH from neurogenic, osteonecrosis, abnormal vascular function, subchondral fracture, heredity and regional acceleration and son on.

[Clinical observation of proximal femoral anti-rotation nail for the treatment of femoral intertrochanteric fracture].

OBJECTIVE: To explore the curative effect and the recessive loss of blooding of PFNA for the treatment of intertrochanteric fractures of femur. METHODS: From January 2012 to January 2015, a total of 49 patients with intertrochanteric fractures of femur were treated with proximal femoral anti-rotation nail including 41 males and 8 females with an average age of 79 years old ranging from 65 to 91 years old. According to the modified Evans type, 1 case was type I, 12 cases were type II, 36 cases were type III. All cases were fresh fractures. Patients had hip pain, movement limited, joint swelling, bruising, extorsion deformity, X-ray and CT examination showed completely fractures. All patients were treated by closed reduction and PFNA internal fixation. Three comminuted fractures using closed reduction were not satisfied, then were treated by limited PFNA fixation after open reduction. RESULTS: The patients' incision got the grade A healing, no complications such as infection and internal fixation failure happened. All patients were followed up from 6 to 36 months (means 22 months). The pain VAS score decreased from preoperative 7.70±1.97 to 1.00±0.26 at 6 months after operation(P<0.01). Harris hip score improved from preoperative 8.70±4.19 to 91.70±5.31 at 6 months after operation(P<0.01). The outcome at 6 months after operation was excellent in 34 cases, good in 7, poor in 1. The fracture healing time was from 8 to 16 weeks with an average of 12 weeks after operation. One patient with osteoporosis, crushing broken, poor compliance, associated with schizophrenia at the same time, appeared with the displacement of the femoral greater trochanter, with conservative treatment for healing. CONCLUSIONS: Intertrochanteric fractures of femur are common in the elderly trauma, in pain relief, recovery of hip function, to provide quality of life for the patients, PFNA achieved satisfactory effect, but its existence is worth to pay close attention to the recessive loss of blood.

Results of a modified posterolateral approach for the isolated posterolateral tibial plateau fracture.

BACKGROUND: There are few posterolateral approaches that do not require the common peroneal nerve (CPN) dissection. With the nerve exposure, it would pose a great challenge and sometimes iatrogenic damage over the surgical course. The purpose was to present a case series of patients with posterolateral tibial plateau fractures treated by direct exposure and plate fixation through a modified posterolateral approach without exposing the common peroneal nerve (CPN). MATERIALS AND METHODS: 9 consecutive cases of isolated posterior fractures of the posterolateral tibial plateau were operated by open reduction and plate fixation through the modified posterolateral approach without exposing the CPN between June 2009 and January 2012. Articular reduction quality was assessment according to the immediate postoperative radiographs. At 24 month followup, all patients had radiographs and were asked to complete a validated outcome measure and the modified Hospital for Special Surgery (HSS) Knee Scale. RESULTS: All patients were followedup, with a mean period of 29 months (range 25-40 months). Bony union was achieved in all patients. In six cases, the reduction was graded as best and in three cases the reduction was graded as middle according to the immediate postoperative radiographs by the rank order system. The average range of motion arc was 127° (range 110°-134°) and the mean postoperative HSS was 93 (range 85-97) at 24 months followup. None of the patients sustained neurovascular complication. CONCLUSIONS: The modified posterolateral approach through a long skin incision without exposing the CPN could help to expand the surgical options for an optimal treatment of this kind of fracture, and plating of posterolateral tibial plateau fractures would result in restoration and maintenance of alignment. This approach demands precise knowledge of the anatomic structures of this region.

Conservative and Operative Treatment in Extension Teardrop Fractures of the Axis.

STUDY DESIGN: A retrospective case series describing teardrop fracture of the axis. OBJECT: The purpose of the study was to clarify the clinical features, the mechanism of injury, and the potential instability of extension teardrop fractures of the axis, so as to emphasize the importance of recognizing this injury as a separate entity. SUMMARY OF BACKGROUND DATA: Teardrop fractures of the axis are rare spinal fractures, comprising only a small percentage of all injuries of the cervical spine. The stability of this fracture pattern has been a matter of debate leading to controversy regarding treatment strategies and the need for stabilization. METHODS: We retrospectively reviewed data collected from 16 patients to document the mechanism of injury, neurological deficit, treatment and clinical outcome, and imaging findings. RESULTS: Extension teardrop fractures accounted for approximately 8.9% of the upper cervical spinal injuries and 12.7% of axis fractures at the authors' institution over the same period. Six patients (4 males and 2 females) underwent surgery (4 by an anterior approach, 2 by a posterior approach). Ten cases underwent Halo-vest immobilization for a period between 6 and 12 weeks. At final follow-up, 14 cases achieved excellent results, whereas 2 patients complained of mild residual neck pain. Maximum cranial-caudal dimensions of the fragments were between 5 and 24 mm (average, 12.9 mm), and the transverse dimensions were between 5 and 22 mm (average, 11.1 mm). Fragment displacement ranged from 1 to 9 mm (average, 3.5 mm), whereas fragment rotation ranged from 10 to 52 degrees (average, 24.4 degrees) in the sagittal plane. CONCLUSIONS: Most patients with an extension teardrop fracture of the axis can be treated conservatively. On the basis of this case series, the authors suggest that large fragment size, displacement or angulation, intervertebral disk injury, neurologic deficit, or signs of instability are reasonable indications for surgical treatment.

Translaminar Screw Fixation in the Upper Thoracic Spine: Computed Tomography-Based Quantitative Laminar Analysis and Feasibility Study of Translaminar Virtual Screw Placement.

Translaminar screws (TLS) offer an alternative to pedicle screw fixation in the upper thoracic spine. Although some studies have described the anatomy of the laminae at the upper thoracic spine, computed tomography (CT) imaging is the modality of choice for presurgical planning. The characteristics of upper thoracic lamina in healthy Han adults have not been ascertained for the safe placement of TLSs. To determine the measurements (the diameter, maximal screw length, and optimal screw trajectory) required for safe TLSs placement in the T1-3 by CT scan evaluation, forty patients (20 men, 20 women), age (48.2 ± 13.9) years (range 19-78 years), were involved in the study from December 2008 to June 2012. Patients received a standardized axial bone-window CT imaging at T1-3, and had no evidence of spinal trauma, bone defect, or deformity. For each lamina, the height, thickness (outer cortical and inner cancellous), maximal screw length, and the crossing angle of the lamina were measured using Syngo 3D software and statistically analyzed. There were no significant differences between the left and right sides for each of the measurements (P > 0.05), but significant differences were determined between males and females for some measurements. The thickness of the laminar outer cortical diameter for the axial reconstruction was higher than that for the sagittal reconstruction (P < 0.01). The T1 lamina was estimated to accommodate, on average, a 4.2-mm longer screw than the T2 lamina, and a 5.7-mm longer screw than the T3 lamina. Most laminae could accept a 4.0-mm screw with a 1.0-mm clearance. Thus, it is more reasonable and accurate to select screw sizes according to the measurement of laminar thickness in the parasagittal reconstruction of the CT scan. T1 crossing laminar screws were successfully placed, without impingement to the spinal canal. Based on the CT evaluation, there are no anatomical limitations to the placement of TLSs at T1-3 in Chinese patients. Gender differences were noted in the superior thoracic vertebrae for dimensions of the laminae, which must be considered when placing TLSs at these levels. The TLSs add to the surgeon's armamentarium for instrumented fixation of the upper thoracic vertebrae.

[Mini-open trans-spatium intermuscular versus percutaneous short-segment pedicle fixation for the treatment of thoracolumbar mono-segmental vertebral fractures].

OBJECTIVE: To compare the clinical effects and radiographic outcomes of mini-open trans-spatium intermuscular and percutaneous short-segment pedicle fixation in treating thoracolumbar mono-segmental vertebral fractures without neurological deficits. METHODS: From August 2009 and August 2012, 95 patients with thoracolumbar mono-segmental vertebral fractures without neurological deficits were treated with short-segment pedicle fixation through mini-open trans-spatium intermuscular or percutaneous approach. There were 65 males and 30 females, aged from 16 to 60 years old with an average of 42 years. The mini-open trans-spatium intermuscular approach was used in 58 cases (group A) and the percutaneous approach was used in 37 cases (group B). Total incision length, operative time, intraoperative bleeding, fluoroscopy, hospitalization cost were compared between two groups. Visual analog scale (VAS) and radiographic outcomes were compared between two groups. RESULTS: All patients were followed up from 12 to 36 months with an average of 19.6 months. No complications such as incision infection, internal fixation loosening and breakage were found. In group A, fluoroscopy time was short and hospitalization cost was lower than that of group B (P<0.05). But the total incision length in group B was smaller than that of group A (P<0.05). There was no significant differences in operative time, intraoperative bleeding, postoperative VAS and radiographic outcomes between two groups (P>0.05). Postoperative VAS and radiographic outcomes were improved than that of preoperative (P<0.05). CONCLUSION: The mini-open trans-spatium intermuscular and percutaneous short-segment pedicle fixation have similar clinical effects and radiographic outcomes in treating thoracolumbar mono-segmental vertebral fractures without neurological deficits. However, in this study, the mini-open trans-spatium intermuscular approach has a short learning curve and more advantages in hospitalization cost and intraoperative radiation exposure times, and is recommendable.

Biomechanical comparison of pedicle screws versus spinous process screws in C2 vertebra: A cadaveric study.

BACKGROUND: Biomechanical studies have shown C2 pedicle screw to be the most robust in insertional torque and pullout strength. However, C2 pedicle screw placement is still technically challenging. Smaller C2 pedicles or medial localization of the vertebral artery may preclude safe C2 pedicle screw placement in some patients. The purpose of this study was to compare the pullout strength of spinous process screws with pedicle screws in the C2. MATERIALS AND METHODS: Eight fresh human cadaveric cervical spine specimens (C2) were harvested and subsequently frozen to -20°C. After being thawed to room temperature, each specimen was debrided of remaining soft tissue and labeled. A customs jig as used to clamp each specimen for screw insertion firmly. Screws were inserted into the vertebral body pairs on each side using one of two methods. The pedicle screws were inserted in usual manner as in previous biomechanical studies. 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° caudally in the sagittal plane and about 0° medially in the axial plane. Each vertebrae was held in a customs jig, which was attached to material testing machine (Material Testing System Inc., Changchun, China). A coupling device that fit around the head of the screw was used to pull out each screw at a loading rate of 2 mm/min. The uniaxial load to failure was recorded in Newton'st dependent test (for paired samples) was used to test for significance. RESULTS: The mean load to failure was 387 N for the special protection scheme and 465 N for the protection scheme without significant difference (t = -0.862, P = 0.403). In all but three instances (38%), the spinous process pullout values exceeded the values for the pedicle screws. The working distances for the spinous process screws was little shorter than pedicle screws in each C2 specimen. CONCLUSION: Spinous process screws provide comparable pullout strength to pedicle screws of the C2. Spinous process screws may provide an alternative to pedicle screws fixation, especially with unusual anatomy or stripped screws.

[Asymmetrical osteotomy for elderly degenerative lumbar kyphoscoliosis].

OBJECTIVE: To investigate the safety and efficacy of asymmetrical osteotomy in treating elderly degenerative lumbar kyphoscoliosis. METHODS: From January 2010 to June 2012,17 elder patients with degenerative lumbar kyphoscoliosis were treated with asymmetrical osteotomy,their data were retrospectively analyzed. There were 6 males and 11 females with an average age of 61 years old (57 to 72). Total length spinal X-ray was performed for all patients before operation,and sagittal and coronal balance were analyzed. The follow-up time was 1 year at least. VAS score, thoracolumbar Cobb angle and pelvic parameters were analyzed. RESULTS: All patients were operated successfully. The average operation time was 210 min (180 to 260) and intraoperative blood loss was 1,100 ml (750 to 2 200). At 1 year after operation, VAS score decreased from preoperative 7.0 +/- 1.5 to 1.1 +/- 0.6; lumbar lordosis (LL) corrected from (1.9 +/- 9.6) degrees to (35.2 +/- 6.7) degrees; thoracic kyphosis (TK) increased from (26.3 +/- 9.7) degrees to (32.5 +/- 11.2) degrees; lumbar scoliosis decreased from (25.1 +/- 11.0) degrees to (7.9 +/- 3.6) degrees; pelvic tilt (PT) restored from (33.0 +/- 10.1) degrees to (25.3 +/- 8.9) degrees; sacral slope (SS) increased from (13.9 +/- 9.7) degrees to (27.2 +/- 11.0) degrees; sagittal balance improved from (10.3 +/- 8.1) cm to (3.1 +/- 4.2) cm,and coronal balance improved from (3.5 +/- 2.1) cm to (1.3 +/- 1.1) cm. There was statistically significant difference above data between preoperation and postoperation. CONCLUSION: Asymmetrical osteotomy can not only correct scoliosis deformity, but also restore lumbar lordosis, and may safely and effectively solve the problem of elderly degenerative lumbar kyphoscoliosis.

[The design and application of anterior cervical pedicle screw-plate system in lower cervical spine].

OBJECTIVE: To explore the applied feasibility of the anterior cervical pedicle screw-plate system in lower cervical spine,in order to provide basic data for clinical application. METHODS: Total thirty-two units (functional spinal unit, FSU) were got randomly from 16 cervical speciments, 8 units in each group of C3,4, C4,5, C5,6 and C6,7. The anterior cervical pedicle screw-plate system was implanted to reconstruct the stability of FSU after discectomy and bone graft. The adaptability was measured between the screw-plate system and vertebral body. X-ray and CT were used to evaluate the accuracy of anterior cervical pedicle screws. The subject will be dissected to identify the situation of involvement if screw perforating the pedicle. RESULTS: Sixty-four anterior pedicle screws were inserted smoothly in the 32 units. The screw and the plate were harmonious locked in the system. The position and length of all screws were satisfactory through X-ray views. However,6 screws perforated the transpedicular (degree 1) according to CT axial views,2 internally cortex and 4 laterally cortex. None perforation was degree 2 or more. None cervical sac compression and nerve root injury was observed in two internal perforation cadavers. One vertebral vein involvement was found in the four lateral perforation screws. The vertebral artery was not pinched though one screw near to the artery. CONCLUSION: The anterior cervical pedicle screw-plate system is adapted to reconstruct in lower cervical spine and it deserved to be used for clinical application.

[Clinical application of anterior transpediclar screw reconstruction in treating lower cervical spine fracture and dislocation].

OBJECTIVE: To investigate the clinical effects of anterior transpediclar screw (ATPS) fixation in treating lower cervical spine fracture and dislocation. METHODS: From January 2009 to December 2011, 18 patients with lower cervical spine fracture and dislocation were treated with ATPS technique, including 12 males and 6 females, aged from 17 to 47 years old with an average of 38.2 years. Severity score of lower cervical spine injuries (SLIC) ranged from 6 to 9 points with an average of 7.5 points. According to ASIA grade of spinal cord injury, 2 cases were classified in grade A, 8 cases in grade B, 6 cases in grade C and 2 cases in grade D. X-ray and CT scan were done after surgery in order to evaluate the safety of ATPS and observe the stability and fusion of injured segment. Spinal cord function was evaluated according to ASIA grade at 3 months after operation and last follow-up. RESULTS: All patients were followed up for 6 to 15 months with an average of 9.5 months. Three months after operation, in aspect of spinal cord function, 8 cases improved 1 grade, 2 cases improved 2 grades; and at final follow-up, 7 cases improved 1 grade, 4 cases improved 2 grades. All patients obtained bony fusion 6 to 8 months after operation with an average of 6.5 months. After operation, 1 case had transient hoarseness and recovered 2 months later;2 cases felt swallowing discomfort, but the symptoms disappeared after about 3 weeks by inhalation. No internal fixation breakage and loosening as well as nerve, blood vessel and esophageal injuries were found. CONCLUSION: As for three columns injury caused by lower cervical spine fracture and dislocation, treatment with anterior transpediclar screw reconstruction can achieve the effect of decompression thoroughly and restore the cervical spine height and physiological curvature. Moreover, this kind of treatment has good stability and can create the favorable conditions for the recovery of spinal cord function.

[Comparison of statics characteristics between anterior transpedicular screws system and vertebral body screws system in lower cervical spine].

OBJECTIVE: To compare statics characteristics between anterior transpedicular screws (ATPS) system and vertebral body screws (VBS) system in lower cervical spine. METHODS: Sixteen fresh cervical specimens were collected and dissected into 32 different units (functional spinal unit, FSU), 8 units in C3,4, C4,5, C5,6 and C6,7 each. The subjects were randomly divided into group A and B. The anterior transpedicular screw-plate system and anterior vertebral body screw-plate system were implanted separately in group A and B. Then, the maximum axial pull out strength was tested and compared between two fixation system. RESULTS: Maximum pull out strength was (604.68 +/- 48.76) N in group A and (488.24 +/- 32.42) N in group B, and there was significant difference between two groups (t = 2.147, P < 0.05). There was no statistically significant difference in all FSU between anterior transpedicular screws system and vertebral body screws system (F(A) = 2.27, F(B) = 2.05, P > 0.05). CONCLUSION: The pull out strength of anterior transpedicular screws system is better than vertebral body screws system, and the anterior transpedicular screws has the biomechanical feasibility in clinic.

Function-preserving reduction and fixation of unstable Jefferson fractures using a C1 posterior limited construct.

STUDY DESIGN: This is a retrospective, clinical, and radiologic study of posterior reduction and fusion of the C1 arch in the treatment of unstable Jefferson fractures. OBJECTIVE: The aim of the study was to describe a new motion-preserving surgical technique in the treatment of unstable Jefferson fracture. SUMMARY OF BACKGROUND DATA: The management of unstable Jefferson fractures remains controversial. The majority of C1 fractures can be effectively treated nonoperatively with external immobilization unless there is an injury to the transverse atlantal ligament (TAL). Conservative treatment usually involves immobilization for a long time in Halo vest, whereas surgical intervention generally involves C1-C2 fusion, eliminating the range of motion of the upper cervical spine. We propose a novel method for the treatment of unstable Jefferson fractures without restricting the range of motion. METHODS: A retrospective review of 12 patients with unstable C1 fractures between April 2008 and October 2011 was performed. They were treated by inserting bilateral posterior C1 pedicle screws or lateral mass screws interconnected by a transversal rod to achieve internal fixation. There were 8 men and 4 women, with an average age of 35.6 years (range, 20-60 y). Presenting symptoms included neck pain, stiffness, and decreased range of motion but none had neurological injury. Seven patients had bilateral posterior arch fractures associated with unilateral anterior arch fractures (posterior 3/4 Jefferson fracture, Landells type II), and 5 had unilateral anterior and posterior arch fractures (half-ring Jefferson fracture, Landells type II). Seven patients had intact TAL, and 5 patients had fractures and avulsion of the attachment of TAL (Dickman type II). RESULTS: A total of 24 screws were inserted. Five cases had screws placed in the lateral mass: 3 because of posterior arch breakage, and 2 because the height of the posterior arch at the entry point was <4 mm. The remaining 7 cases had pedicle screw fixation. One patient had venous plexus injury during exposure of lower margin of the posterior arch; however, successful hemostasis was achieved with Gelfoam. Postoperative x-ray and computed tomography scan showed partial breach of the transverse foramen caused by a screw in 1 case, and breach of the inner cortex of the pedicle caused by screw displacement in 1 case; however, no spinal cord injury or vertebral artery injury was found. The remaining screws were in good position. Patients were followed up for 6-40 months (average, 22 mo). All cases had recovery of range of motion of the cervical spine to the preinjury level by 3-6 months after surgery, with resolution of pain. At 6 months follow-up, plain radiographs and computed tomography scans revealed satisfactory cervical alignment, no implant failure, and satisfactory bony fusion of the fractures; no C1-C2 instability was observed on the flexion-extension radiographs. CONCLUSIONS: C1 posterior limited construct is a valid technique and a feasible method for treating unstable Jefferson fractures, which allows preservation of the function of the craniocervical junction, without significant morbidity.