Comparative tomographic study of the iliac screw and the S2-alar-iliac screw in children

OBJECTIVES: The recent advancements in spine fixation aid in the treatment of complex spinal pathologies. Both the iliac screw (IS) and the S2-alar-iliac (S2AI) screw provide adequate stability in the fixation of complex lumbosacral spine pathologies, leading to a significant increased rate of using these techniques in the daily practice of the spine surgeons. This study aims to analyze, describe, and compare the insertion and positioning parameters of the S2AI screw and IS techniques in children without spinal deformities. METHODS: An observational retrospective study was conducted at a university hospital in 2018, with 25 computed tomography (CT) images selected continuously. Mann-Whitney-Shapiro-Wilk tests were performed. The reliability of the data was assessed using the intraclass correlation. The data were stratified by age group only for Pearson's correlation analysis. RESULTS: The mean age was 11.7 years (4.5 SD). The mean IS length was 106.63 mm (4.59 SD). The mean length of the S2AI screw was 104.13 mm (4.22 SD). The mean skin distance from the IS entry point was 28.13 mm (4.27 SD) and that for the S2AI screw was 39.96 mm (4.54 SD). CONCLUSIONS: Through CT, the S2AI screw trajectory was observed to have a greater bone thickness and skin distance than the IS. There was a linear correlation between age and screw length for both techniques. A similar relationship was observed between skin distance and age for the S2AI screw technique. In children, the S2AI screw technique presents advantages such as greater cutaneous coverage and implant thickness than the IS technique.

Multi-Rod Constructs Can Increase the Incidence of Iliac Screw Loosening after Surgery for Adult Spinal Deformity

STUDY DESIGN: A retrospective study. PURPOSE: To investigate the incidence of iliac screw loosening with a two-rod vs. multi-rod construct and the effect on clinical and radiographic outcomes after surgery for adult spinal deformity (ASD). OVERVIEW OF LITERATURE: Multi-rod construct is useful for preventing rod fracture in ASD surgery. However, limited information is available regarding the incidence of iliac screw loosening after corrective fusion surgery using a multi-rod construct. METHODS: Total 106 patients with ASD (24 men and 82 women; mean age, 68 years) who underwent corrective fusion surgery using bilateral iliac screws and were followed up for at least 1 year were reviewed. The following variables were compared between patients who underwent surgery with a two-rod and multi-rod construct: age, sex, bone mineral density (BMD), fusion level, high-grade osteotomy, L5/S interbody fusion, screw loosening (upper instrumented vertebra [UIV], S1, and iliac), rod fracture, proximal junctional kyphosis, spinopelvic parameters, and Oswestry Disability Index (ODI) score. We also compared patients with and without iliac screw loosening in the multi-rod construct group. RESULTS: Of the 106 patients, 55 underwent surgery with a conventional two-rod construct and 51 with a multi-rod construct (three rods in 16, four rods in 35). Iliac and UIV screw loosening was observed in 24 patients (21%) and 35 patients (33%), respectively. The multi-rod group showed significantly higher incidence of iliac and UIV screw loosening and lower incidence of rod fracture. Patients with iliac screw loosening had a lower BMD than those without screw loosening; however, no significant differences were observed in the spinopelvic parameters or the ODI score. CONCLUSIONS: The use of multi-rod constructs led to a higher incidence of junctional screw loosening than the use of conventional two-rod constructs, especially in patients with osteoporosis. Iliac screw loosening did not affect sagittal alignment or clinical outcome in the short term.

Spino-Pelvic Fixation in Unstable Sacral Fracture: A Case Report

A 22-year-old female patient visited the emergency room (ER) after a pedestrian traffic accident in a drunken state. An examination at the ER revealed fractures at the right side of the sacral ala, sacral foramina, left anterior acetabulum, right inferior ramus, and right superior articular process of S1. She underwent spino-pelvic fixation and iliosacral (IS) screw fixation. One year later, bone union was completed and implant removal was performed and the treatment was completed without complications. The authors recommend spino-pelvic fixation and IS screw fixation for unstable sacral fractures as one of the excellent methods for obtaining posterior stability of the pelvis among the various treatments of unstable sacral fractures.

Finite element comparative study of S2 alar-iliac screw and sacroiliac joint screw in treatment of type C sacroiliac joint dislocation / 中华创伤杂志

Objective To compare the biomechanical characteristics between S2 alar-iliac (S2AI) screw and sacroiliac joint screw in treating unilateral type C sacroiliac joint dislocation. Methods A 25 year-old healthy male adult agreed to take computed tomography scan of the pelvis. The pelvic floor thickness was 1 mm and the image data were saved in DCOM format. A three dimensional finite element model of intact pelvis was reconstructed by Mimics, Geomagic, SolidWorks, and Abaqus softwares. A finite element model of type C unilateral sacroiliac dislocation was established. One S1 vertebral sacroiliac screw of 6.5 mm in diameter (S1 group), one S2AI screw (S2AI group) and one Si vertebra sacroiliac screw + one S2 vertebra sacroiliac screw (S1+S2 group) were placed in the model, respectively. The500 N vertical load on the upper surface of the sacrum was simulated. The displacement value of sacroiliac joint, the displacement of sacrum, the stress value of the internal fixation and surrounding bone, and the stress distribution cloud map were recorded and analyzed. Results The displacement data showed that displacement distribution in the three groups had a consistent trend. In terms of the absolute value of displacement the result was S, group＞S 2AI group＞S1+ S2 group, of which the maximum displacement of sacroiliac joint in S1 groups was 0.87 mm and that of sacrum was 1.6 mm; the maximum displacement of sacroiliac joint in S2 AI group was 0.22 mm, and that of sacrum was 0.24 mm; the maximum displacement of the sacroiliac joint in S1 + S2 group was 0.06 mm, and that of sacrum was0.16 mm. Stress data showed that the stress in the internal fixation was mainly distributed at the sacroiliac joint, and the stress result was S2AI group＞S, group＞S, + S2 group, of which the maximum stress value was 52.8 MPa in S1 group, 62.1 MPa in S2AI group, and 38.2 MPa in S1 + S2 group. The stress around the screws was also concentrated at the sacroiliac joint, and the stress result was S1 group＞S2AI group＞S1 + S2 group, of which the maximum stress value was 56.8 MPa in S1 group, 11.2 MPa in S2AI group, and 5.8 MPa in S1 + S2 group. Conclusions Single S1 screw, single S2 AI screw and S, screws combined S2 screws can be used for the treatment of unilateral C type sacroiliac joint dislocation. Early weight bearing of single S1 screw might lead to the risks of increased sacroiliac joint displacement and internal fixation failure. S2 AI screw fixation and S1 + S2 screw fixation have similar biomechanical strength, allowing early weight-bearing and contributing to better postoperative rehabilitation.

Freehand S2 Alar-Iliac Screw Placement Using K-Wire and Cannulated Screw: Technical Case Series

OBJECTIVE: Among the various sacropelvic fixation methods, S2 alar-iliac (S2AI) screw fixation has several advantages compared to conventional iliac wing screw. However, the placement of S2AI screw still remains a challenge. The purpose of this study was to describe a novel technique of free hand S2AI screw insertion using a K-wire and cannulated screw, and to evaluate the accuracy of the technique.METHODS: S2AI screw was inserted by free hand technique in sixteen consecutive patients without any fluoroscopic guidance. The gearshift was advanced to make a pilot hole passing through the sacroiliac joint and directing the anterior inferior iliac spine. A K-wire was placed through the pilot hole. After introducing a cannulated tapper along with the K-wire, a cannulated S2AI screw was installed over the K-wire.RESULTS: Thirty-three S2AI screws were placed in sixteen consecutive patients. Thirty-two screws were cannulated screws, and one screw was a conventional non-cannulated screw. Thirty out of 32 (93.8%) cannulated screws were accurately positioned, whereas two cannulated screws and one non-cannulated screw violated lateral cortex of the ilium.CONCLUSION: The technique using K-wire and cannulated screw can provide accurate placement of free hand S2AI screw.

Percutaneous S2-alar-iliac screw fixation for lower lumbar spondylodiscitis with no neurological symptoms in elderly patients: analysis of short-term curative effect / 介入放射学杂志

Objective To evaluate the short-term efficacy of percutaneous S2-alar-iliac screw (S2AIS) fixation for the treatment of lower lumbar spondylodiscitis with no neurological symptoms in elderly patients.Methods The clinical data of 28 patients of lower lumbar spondylodiscitis with no neurological symptoms,who were admitted to the Ward of Spine,Department of Orthopaedics,General Hospital of Shenyang Military Region,China,to receive percutaneous S2AIS fixation,were retrospectively analyzed.The operation was performed by the same surgeon for all patients.A total of 56 S2AIS fixation procedures were accomplished.The patients' age varied from 71 to 79 years old.The spondylodiscitis was located at IAL5 or L5-S1.After the treatment,the patients were followed up for a mean of 6.67 months.The mean operative time,the amount of intraoperative blood loss,the postoperative bed time,the average hospitalization days and the postoperative wound healing were documented and analyzed.The Oswestry score,visual analogue score,erythrocyte sedimentation rate,C reactive protein level were determined before operation as well as at one week and 6 months after operation,and postoperative CT was performed to check the loosening of internal screw fixation.The results were compared and analyzed.Results The mean operative time was (158.12±4.32) min,the average amount of intraoperative blood loss was (25.34±3.23) ml,the average postoperative bed time was (1.34±0.35) d,and the average hospitalization time was (7.29±1.34) d.Poor surgical incision healing was seen in only one patient,and the postoperative wound healing rate was up to 96.42％.Loosening of right S2AIS was detected in one patient,with the screw loosening rate being 1.79％.The Oswestry scores determined at one week and 6 months after treatment were 32.21 and 23.20 respectively,which were significantly different from the preoperative score (P＜0.05).The visual analogue scores determined at one week and 6 months after treatment were 2.17 and 1.25 respectively,which were significantly different from the preoperative score (P＜0.05).At one week and 6 months after treatment,the erythrocyte sedimentation rates were 15.32 mm/h and 14.56 mm/h respectively,and the C reactive protein levels were 7.89 mg/L and 8.90 mg/L respectively,both of which were significantly different from the preoperative ones (both P＜0.05).Conclusion For the treatment of lower lumbar spondylodiscitis with no neurological symptoms in elderly patients,percutaneous S2AIS fixation has certain advantages,such as less trauma,less blood loss,early postoperative ambulation,remarkable improvement of clinical symptoms,etc.with satisfactory short-term clinical efficacy.

Freehand S2 Alar-Iliac Screw Placement Using K-Wire and Cannulated Screw: Technical Case Series

OBJECTIVE: Among the various sacropelvic fixation methods, S2 alar-iliac (S2AI) screw fixation has several advantages compared to conventional iliac wing screw. However, the placement of S2AI screw still remains a challenge. The purpose of this study was to describe a novel technique of free hand S2AI screw insertion using a K-wire and cannulated screw, and to evaluate the accuracy of the technique. METHODS: S2AI screw was inserted by free hand technique in sixteen consecutive patients without any fluoroscopic guidance. The gearshift was advanced to make a pilot hole passing through the sacroiliac joint and directing the anterior inferior iliac spine. A K-wire was placed through the pilot hole. After introducing a cannulated tapper along with the K-wire, a cannulated S2AI screw was installed over the K-wire. RESULTS: Thirty-three S2AI screws were placed in sixteen consecutive patients. Thirty-two screws were cannulated screws, and one screw was a conventional non-cannulated screw. Thirty out of 32 (93.8%) cannulated screws were accurately positioned, whereas two cannulated screws and one non-cannulated screw violated lateral cortex of the ilium. CONCLUSION: The technique using K-wire and cannulated screw can provide accurate placement of free hand S2AI screw.

Comparison of clinical complications of iliac screw fixation versus S2 alar-iliac screw / 局解手术学杂志

Objective To compare the clinical complications between S2 alar-iliac(S2AI) screw and iliac screw(IS) fixation technique.Methods The data of 65 patients who were diagnosed as degenerative scoliosis and underwent spinopelvic fixation in our hospital from August 2010 to July 2012 were retrospectively reviewed.These patients were divided into the iliac screw fixation group (IS group) with 43 patients and the S2 alar iliac fixation group (S2AI group) with 22 patients according to different methods.The complications included screw loosening,screw breakage,acute infections,delayed wound infection and persistent pain over the gluteal region occurring longer than 3 months postoperatively were recorded.Results There were 8cases with screw loosening and 13 cases with gluteal pain in IS group,while there were no screw loosening and only 2 cases with gluteal pain in S2AI group.The average onset of gluteal pain were 11.8 months postoperatively in the IS group and 18 months postoperatively in the S2AI group.It showed that the absolute risk reduction(ARR) of screw loosening and late pain in the S2AI group was 18.6%,which was lower than 21.1% in the IS group. In the IS group, there were a total of 5 cases of delayed wound infection. Finally,3 caes of them were cured by irrigation and debridement only.and the other 2 cases were cured by irrigation and debridement with implant removal.There were no cases of delayed wound infection in the S2AI group.Conclusion The S2AI technique is associated with significantly less clinical and radiographic complications when compared with the iliac screws technique,it is a kind of internal fixation of spine and pelvis,which is worthy of being popularized by spine surgeons.

Complications and Risk Factors of Surgery for Adult Spine Deformity / 대한정형외과학회잡지

Demand for surgical management of adult spine deformity has increased due to a recent increase in the elder population, development of surgical techniques, and increased desire for a better quality of life. More surgeries led to more and various complications. Complications of surgery for adult spine deformity have been reported from 37% to 53% depending on the types of disease, cause, and patient. This rate is higher than complications from general spine surgeries. Complications of surgery for adult spine deformity include; infection, excessive bleeding, nerve injury, pseudarthrosis, adjacent segment disease, and iliac screw complication. Factors influencing these complications include; old age, diabetes, steroid use, and osteoporosis. Proximal junctional kyphosis (PJK) is an abnormal kyphosis at the proximal level of the instrument after spine deformity surgery. Risk factors for PJK include; injury of paravertebral muscles and posterior ligament complex, over- and under-correction of coronal sagittal imbalance, age older than 55 years, and osteoporosis. There is a high risk of unexpected complications during surgery for adult spine deformity. Patients with degenerative spine sagittal imbalance are more prevalent in Korea than in Western countries. They tend to be old, have underlying diseases and osteoporosis, making them susceptible to complications related to instrumentation. Postoperative satisfaction tends to be low thus surgeons need to take care when selecting surgical methods and fusion level.

Lumbopelvic Fixation with Iliac Screw in Spinopelvic Dissociation / 대한정형외과학회잡지

PURPOSE: Spinopelvic dissociation which occurs by high energy trauma with associated fractures is rare. Treatment is difficult and only a few studies on treatment of spinopelvic dissociation have been reported. Therefore we evaluated spinopelvic dissociation patients treated with iliac screw. MATERIALS AND METHODS: We analyzed patients who underwent surgery using an iliac screw from 2005 to 2010. Preoperative radiologic classification was performed using the level of the transverse fracture line of the sacrum, shape of the fracture, and Roy-Camille classification. Neurologic evaluation was performed using Gibbons classification. Eleven patients underwent surgery with a pedicle screw in 1 level (L5 to S1) and bilateral iliac screws were added. RESULTS: A total of 11 patients were included in this study. The level of the transverse fracture line of the sacrum was mainly at S2, and there were mostly type 3 or 4 in Roy-Camille classification. Bony union was checked in 11 patients without metal failure. Six of 7 patients were treated by posterior decompression. Among them, 5 patients recovered from neurological deficit and 1 patient still had a sensory disorder on both lower legs. CONCLUSION: The more displacement of fracture, the more neurologic deficit occurred. In addition, we think that aggressive surgical treatment for spinopelvic dissociation should be considered, because a good clinical result was achieved with 1 level (L5 to S1) fixation and bilateral iliac screw fixation.

Management of Sacral Tumors Requiring Spino-Pelvic Reconstruction with Different Histopathologic Diagnosis: Evaluation with Four Cases

In this retrospective study, surgical results of four patients with sacral tumors having disparate pathologic diagnoses, who were treated with partial or total sacrectomy and lumbopelvic stabilization were abstracted. Two patients were treated with partial sacral resection and two patients were treated with total sacrectomy and spinopelvic fixation. Fixation methods included spinopelvic fixation with rods and screws in two cases, reconstruction plate in one case, and fresh frozen allografts in two cases. Fibular allografts used for reconstruction accelerated bony union and enhanced the stability in two cases. Addition of polymethyl methacrylate in the cavity in the case of a giant cell tumor had a positive stabilizing effect on fixation. As a result, we can conclude that mechanical instability after sacral resection can be stabilized securely with lumbopelvic fixation and polymethyl methacrylate application or addition of fresh frozen allografts between the rods can augment the stability of the reconstruction.

Free Hand Insertion Technique of S2 Sacral Alar-Iliac Screws for Spino-Pelvic Fixation: Technical Note, Acadaveric Study

A rigid spino-pelvic fixation to anchor long constructs is crucial to maintain the stability of long fusion in spinal deformity surgery. Besides obtaining immediate stability and proper biomechanical strength of constructs, the S2 alar-iliac (S2AI) screws have some more advantages. Four Korean fresh-frozen human cadavers were procured. Free hand S2AI screw placement is performed using anatomic landmarks. The starting point of the S2AI screw is located at the midpoint between the S1 and S2 foramen and 2 mm medial to the lateral sacral crest. Gearshift was advanced from the desired starting point toward the sacro-iliac joint directing approximately 20degrees angulation caudally in sagittal plane and 30degrees angulation horizontally in the coronal plane connecting the posterior superior iliac spine (PSIS). We made a S2AI screw trajectory through the cancellous channel using the gearshift. We measured caudal angle in the sagittal plane and horizontal angle in the coronal plane. A total of eight S2AI screws were inserted in four cadavers. All screws inserted into the iliac crest were evaluated by C-arm and naked eye examination by two spine surgeons. Among 8 S2AI screws, all screws were accurately placed (100%). The average caudal angle in the sagittal plane was 17.3+/-5.4degrees. The average horizontal angle in the coronal plane connecting the PSIS was 32.0+/-1.8degrees. The placement of S2AI screws using the free hand technique without any radiographic guidance appears to an acceptable method of insertion without more radiation or time consuming.

Changes of Spinopelvic Parameter using Iliac Screw In Surgical Correction of Sagittal Imbalance Patients

STUDY DESIGN: A retrospective-based study. OBJECTIVES: To evaluate the usefulness of iliac screws in the surgical correction of sagittal imbalance by changes of spinopelvic parameters. SUMMARY OF LITERATURE REVIEW: Although reports exist regarding the fusion rates on lumbosacral fusion by iliac screws, no previous studies address the issue of changes of spinopelvic parameters on surgical correction of sagittal imbalance by iliac screws. MATERIALS AND METHODS: We analyzed a total of 23 patients who were operated on by pedicle subtraction osteotomy and posterior fusion on sagittal imbalance. Patients were divided into two groups: 1) non-iliac screw fixation and; 2) iliac screw fixation. The two groups were compared during the preoperative and postoperative stages, and the last follow-up spinopelvic parameters of two groups. RESULTS: Spinopelvic parameters, except for pelvic incidence, were corrected after surgery; some corrected values of spinopelvic parameters were lost during follow-up. There was a statistically significant difference in the last follow-up period between lumbar lordosis and pelvic tilt. Values of postoperative lumbar lordosis and pelvic tilt was similar to each other; however, during the follow-up period corrected values of spinopelvic parameters of non-iliac screw fixation group were more lost. There were no statistically significant changes in postoperative and last follow-up sacral slope and pelvic incidence. CONCLUSIONS: Sagittal imbalance could be corrected by pedicle subtraction osteotomy, and corrected values of lumbar lordosis and pelvic tilt of iliac screw fixation group could be maintained well compared to non-iliac screw fixation. Iliac screw fixation could be useful for maintenance of corrected values of spinopelvic parameters in surgical correction of sagittal imbalance.

Lumbosacral Fixation Using the Diagonal S2 Screw for Long Fusion in Degenerative Lumbar Deformity: Technical Note Involving 13 Cases

Placing instrumentation into the ilium has been shown to increase the biomechanical stability and the fusion rates, but it has some disadvantages. The diagonal S2 screw technique is an attractive surgical procedure for degenerative lumbar deformity. Between 2008 and 2010, we carried out long fusion across the lumbosacral junction in 13 patients with a degenerative lumbar deformity using the diagonal S2 screws. In 12 of these 13 patients, the lumbosacral fusion was graded as solid fusion with obvious bridging bone (92%). One patient had a rod dislodge at one S2 screw and breakage of one S1 screw and underwent revision nine months postoperatively. So, we present alternative method of lumbopelvic fixation for long fusion in degenerative lumbar deformity using diagonal S2 screw instead of iliac screw.

Complications of Iliac Screw in Spinopelvic Fixation With Adult Spinal Deformity: Complications of Iliac Screw in Spinopelvic Fixation

STUDY DESIGN: Retrospective study. OBJECTIVES: To evaluate clinical & radiologic significance about complications of spinopelvic fixation with iliac screw in patients with adult spinal deformity. SUMMARY OF LITERATURE REVIEW: Complications of iliac screw fixation in adult spinal deformity patients was obscure in spite of the good results of iliac screw fixation. MATERIALS AND METHODS: We analyzed 27 patients, followed over 1-year, with adult spinal deformity (lumbar degenerative kyphosis, degenerative lumbar scoliosis, flat back syndrome). The study was done for complications of iliac screw fixation by clinical and radiological evaluations. RESULTS: Post-operative iliac screw prominence were 15 cases (55.5%), iliac screw breakage was 1 case (3.7%), bursitis was 1 case (3.7%), sacroiliac joint pain were 5 cases (18.5%), halo sign around iliac screw were 23 cases (85.1%), and 3 cases (11.1%) were performed reoperation. There was no significance between halo sign and sacroiliac joint pain. CONCLUSIONS: Iliac screw fixation is a very useful operative method without severe complications on spinopelvic fixation. There are some complications of iliac screw fixation and iliac screw prominence is a most common problem, but few counterplan exits. So, further studies about reducing complication method, management protocols of iliac screw complication were needed.

Treatment of Unstable Sacral Fractures Related to Spino-Pelvic Dissociations

PURPOSE: To evaluate the outcomes of surgical treatment modality in unstable sacral fractures combined with spinal and pelvic ring injury depending on the presence of spino-pelvic dissociations. MATERIALS AND METHODS: The subjects were 16 patients, with unstable sacral fractures combined with spinal and pelvic ring injuries, were operated from July 2004 to January 2011. The patients were divided into 2 groups depending on the presence of spino-pelvic dissociations: those with dissociations were group 1, and those without dissociations were group 2. Group 1 was treated with spino-pelvic fixations using iliac screw, while group 2 was treated with percutaneous iliosacral screw fixations. The availability of the radiological bony union with its application periods, and clinical results using visual analogue scale (VAS) and oswestry disability index (ODI) were evaluated, retrospectively. RESULTS: Out of 16 patients, 8 patients in group 1 were treated with spino-pelvic fixation using iliac screw, and 8 patients in group 2 were treated with percutaneous iliosacral screw fixation. The mean bony union period was 17.4 weeks in group 1, and 19.6 weeks in group 2. The Mean VAS and ODI scores on the last follow-up were 2.5 points and 15.6 points in group 1, 2 points and 18.8 points in group 2, respectively. Both groups had favorable clinical results at the last follow-up. CONCLUSION: For surgical treatments of unstable sacral fractures, spino-pelvic fixation using iliac screws is advised for cases with combined spino-pelvic dissociation, while percutaneous iliosacral screw fixation is advised for cases without combined dissociation.

The Trajectory of Iliac Screw in the Axial Plane in 200 Korean Patients

STUDY DESIGN: A retrospective radiographic analysis. PURPOSE: To estimate the accurate trajectory in the axial plane for iliac screw insertion in 200 Korean patients using radiographic images. OVERVIEW OF LITERATURE: Several complications have been encountered after fusion to the lumbosacral junction, including pseudarthrosis, S1 screw loosening, and sacral fractures. Iliac screw fixation is considered an efficient method for augmenting sacral screw fixation but there are few reports on the trajectory of iliac screw insertion. The trajectory in the sagittal plane can be visualized by intraoperative fluoroscopy. However, there is no method to check the accuracy of the trajectory in the axial plane during surgery. METHODS: Between January 2007 and February 2009, 200 patients (107 men and 93 women) who underwent L-spine computed tomography were enrolled in this study. The mean age of the patients was 55.6 +/- 18.3 years (range, 13 to 92 years). The spino-iliac angle (SIA) was measured on the axial image at the S1 level, which was defined as the angle between a vertical line through the center of the spinous process and an oblique line that passed through the center of the outer and inner cortices of the ilium. RESULTS: The group mean SIA was 30.1degrees +/- 7.8degrees; 30.1degrees +/- 7.7degrees for men and 29.9degrees +/- 81.1degrees for women. There was no significant difference according to gender or age (p > 0.05). CONCLUSIONS: The SIA for the axial trajectory of iliac screws is approximately 30degrees in Korean patients.

Spinopelvic Fixation / 대한척추외과학회지

Lumbosacral fixation or spinopelvic fixation is frequently required for the surgical treatment of neuromuscular scoliosis and degenerative lesions, trauma and tumor in the lumbosacral vertebrae. However, the establishment of stable fixation with these procedures is difficult due to the anatomic characteristics of the sacrum and this is even more problematic for the cases with long segmental fixation, severe instability and bone defects. Although the emergence of pedicle screws makes spinal fixation easier and more rigid, S1 pedicle screws alone do not provide enough stability for lumbosacral fixation. For the purposes of reinforcing lumbosacral fixation, procedures using rods or screws can be used: the procedures using rods include the Galveston method, the McCarthy S-rod and the Jackson intrasacral rod, and the procedures using screws include sacral alar screws, transdiscal screws and iliac screws. The purpose of this study was to ascertain the proper fixation methods, according to each indication, for spinopelvic fixation and we analyzed the advantages and drawbacks of each fixation method. In addition, the fixation method of iliac screws, which has recently become more popular, is presented in detail to enhance the availability and reduce the complication of this technique.

Radiologic Analysis of Postoperative Sagittal Plane Correction in Lumbar Degenerative Kyphosis (LDK) / 대한척추외과학회지

STUDY DESIGN: This is a retrospective study OBJECTIVES: We radiologically analyzed the correction of the sagittal imbalance and the proximal fusion level to prevent correction loss and the usefulness of iliac screws in LDK. SUMMARY OF THE LITERATURE REVIEW: Complications can be encountered during fixation and fusion as most of the LDK patients are aged, and the osteoporosis that causes fixation loss is known to affect the loss of correction. MATERIALS AND METHODS: We analyzed the cause of correction loss among 35 patients who underwent surgery and who were followed up for at least 1 year. All the patients had performed gait analysis before operation. The operative techniques were pedicle subtraction osteotomy and fixation to S1. For analyzing causes of correction loss, we analyzed the degrees of lumbar lordosis for the sagittal correction and the degrees of the preoperative thoracolumbar kyphosis for the proximal fusion range. For analyzing the usefulness of iliac screws, the subjects were divided into two groups: 1) the -iliac screw (23cases) group for the patients who were fixed without iliac screws and 2) the +iliac screw (12cases) group for the patients who were fixed with iliac screws. RESULTS: There were no patients who had marked anterior pelvic tilt. It is important to correct the lumbar lordosis over 20degrees compared with the preoperative thoracic kyphosis. There are 10 cases of preoperative thoracolumbar kyphosis > or = 10degrees and 25 cases of preoperative thoracolumbar kyphosis or = 10degrees, 4 cases that were fixed to T10 had no sagittal correction loss, and 2 of the 6 cases that were fixed to T11 or T12 had sagittal correction loss. For the 25 cases of preoperative thoracolumbar kyphosis < 10degrees, 5 cases that were fixed to T10 had no sagittal correction loss and 1 of the 20 cases that were fixed to T11 or T12 had sagittal correction loss (p<0.05). 6 cases (26%) in the -iliac screw group (23 cases total) and 1 case (8%) in the +iliac screw (12 cases total) showed sagittal correction loss (p<0.05). CONCLUSIONS: It is important to make the postoperative lumbar lordosis over 20degrees compared with the preoperative thoracic kyphosis for correcting sagittal imbalance, to decide on the proximal fixation level according to the preoperative thoracolumbar kyphosis and to fix with iliac screws.

Lumbo-sacro-pelvic Fixation Using Iliac Screws for the Complex Lumbo-sacral Fractures

Fractures of lumbo-sacral junction involving bilateral sacral wings are rare. Posterior lumbo-sacral fixation does not always provide with sufficient stability in such cases. Various augmentation techniques including divergent sacral ala screws, S2 pedicle screws and Galveston rods have been reported to improve lumbo-sacral stabilization. Galveston technique using iliac bones would be the best surgical approach especially in patients with bilateral comminuted sacral fractures. However, original Galveston surgery is technically demanding and bending rods into the appropriate alignment is time consuming. We present a patient with unstable lumbo-sacral junction fractures and comminuted U-shaped sacral fractures treated by lumbo-sacro-pelvic fixation using iliac screws and discuss about the advantages of the iliac screws over the rod system of Galveston technique.