Triangular Osteosynthesis for Unstable Sacral Fractures

Objective Stable internal fixation of sacral fractures after anatomic reduction of the vertical displacement. Decompression of nerve roots. Early return to pain-free function. Indications All vertically unstable sacral fractures of type C pelvic ring disruptions. Sacroiliac dislocations. Contraindications Compound fractures. Soft tissue detachment of posterior pelvic ring or fractures associated with considerable soft tissue trauma constitute a contraindication limited to the immediate post-injury phase given the rist of infection and soft tissue complications. Surgical Technique Curvilinear or paravertebral posterior approach. Reduction of the fracture, stabilization between pedicle of L4 or L5 and posterior aspect of the iliac bone or the sacral wing lateral to the sacral fracture. Thereafter, iliosacral screw fixation (unilateral fractures with little displacement) or transsacral plate fixation (bilateral fractures or unilateral fractures with marked displacement). If a stabilization of the anterior pelvic ring has been performed, 1 iliosacral screw is sufficient, otherwise 2 screws should be used. Stabilization of the anterior pelvic ring is only indicated in the presence of disruption of the symphysis, marked displacement of fragments, or if associated injuries necessitate an anterior approach. Results Since April 1992, vertically unstable sacral fractures were treated with this stabilization in 48 patients (average age 34 years, range 15 to 72 years). Since 1994, the start of postoperative full weight-bearing was gradually advanced. Despite the immediate postoperative full weight-bearing, a loss of reduction was not observed in properly performed triangular internal fixation. An incomplete reduction associated with an inadequate stabilization led to a loss of correction in 3 patients. Prominent heads of pedicle screws at the level of the posterior iliac crest may cause soft tissue problems. All fractures consolidated. Implant removal was performed in 23 patients, in 1 patient on accound of deep infection and in 22 after consolidation of the fracture. Out of 25 patients with preoperative neurologic deficit, 4 showed a complete and 3 a partial recovery.     

Variations in sacral morphology and implications for iliosacral screw fixation

Posterior pelvic percutaneous fixation following either closed or open reduction is a popular procedure. Knowledge of the posterior pelvic anatomy, its variations, and related imaging is critical to performing reproducibly safe surgery. The dysmorphic sacrum has several key characteristics. The upper portion of the sacrum is relatively colinear with the iliac crests on the outlet radiographic view. Other characteristics include the presence of mammillary bodies (ie, underdeveloped transverse processes) at the sacral mid-alar area, anterior upper sacral foramina that are not circular, residual upper sacral disks, an acute alar slope oriented from cranial-posterior-central to caudal-anterior-lateral on the outlet and lateral views of the sacrum, a tongue-in-groove sacroiliac joint surface visualized on CT, and cortical indentation of the anterior ala on the inlet radiographic view. The surgeon must be knowledgeable about individual patient anatomy to ensure safe iliosacral screw placement.     

骶髂关节经皮拉力螺钉固定钉道参数的解剖学测量

目的 为经S_1椎弓根水平骶髂关节拉力螺钉固定术提供应用解剖学依据.方法 2008年6月至2009年7月收集50个成人骨盆的螺旋CT扫描数据,重建骨盆三维模型,模拟经皮托力螺钉固定.测量S_1椎弓根的宽和高、骶髂关节拉力螺钉的进针点和进针方向、进针点至S_1椎体对侧前皮质和髂后上棘的距离.结果 S_1椎弓根的宽和高分别为(20.43±1.63)mm和(20.26±0.99)mm;2枚螺钉的进针点均在髂前上棘和髂后上棘的连线上方,至髂后上棘的距离分别为(49.87±6.80)mm和(51.11±7.15)mm.螺钉平行进入S_1椎弓根,与髂骨翼后外侧面垂直,与冠状面和欠状面的夹角分别为18.35°±5.20°和77.62°±3.98°.进针点到S1椎体对侧前皮质的距离分别为(76.08±4.32)mm和(77.62±3.98)mm.骶髂关节拉力螺钉的长度、S_1椎弓根的高度和宽度、进针点到髂后上棘的距离、进针点与冠状面的夹角在男女之间差异有统计学意义(P<0.05).结论 正常成人在S_1椎弓根水平均町置入2枚直径为6.5 mm的拉力螺钉,钉道参数的解剖学测量为骶髂关节拉力螺钉固定手术导航模板的设计提供了理论基础.     

骨盆损伤中移位骶骨骨折的手术治疗

目的 探讨不稳定型骨盆损伤中移位骶骨骨折的手术方法及治疗效果.方法 对2000年9月至2007年9月收治的33例伴有骶骨骨折的骨盆损伤患者行手术治疗.根据AO/OTA的分型方法,骨盆B型损伤5例,C型28例.根据Denis的分型方法,骶骨I型骨折13例、Ⅱ型11例、Ⅲ型9例.其中早期合并原发性神经损伤23例.骶骨骨折应用张力带钢板固定1例;脊柱椎弓根钉棒系统经骨盆后方沿双侧髂嵴横向固定10例,经L_(4,5)或L_5S_1及双侧髂嵴后方纵向固定16例;骶髂螺钉固定3例;骶骨棒固定2例;骶髂螺钉联合骶骨棒固定1例.术中间期行椎板切除、马尾神经减压11例,二期行神经松解、骶前孔扩大术2例.结果 术后随访12～82个月,平均27.3个月.根据Majeed疗效标准,优17例、良7例、可2例、差7例.骶骨I型骨折疗效优良率为92.3%、Ⅱ型为72.7%、Ⅲ型为44.4%.神经损伤恢复情况在手术治疗组中优6例、良4例、无变化3例;在非手术治疗组中优6例、良1例、无变化3例.术后并发症包括腰骶部切口深部感染2例,腰骶僵硬不适2例.神经损伤一过性加重4例,迟发性骶神经损伤3例.结论 手术治疗是改善骶骨骨折复位质量的重要途径,骨盆前、后环损伤的联合制动是提高骨折内同定强度的有效方法.对手术指征明确的骶神经损伤,早期定位减压有助于其功能恢复.     

Safe placement of S1 and S2 iliosacral screws: the "vestibule" concept

OBJECTIVES: To determine the optimal starting points for placement of S1 and S2 iliosacral screws as well as the pertinent anatomy surrounding the S1 and S2 vertebral bodies. DESIGN: Normal subject study evaluating helical CT scans of thirty normal posterior pelvic rings. SETTING: Methodist Hospital, Indianapolis, Indiana, Level I trauma center. PARTICIPANTS: Consenting adults for limited pelvis CT. MAIN OUTCOME MEASUREMENTS: The three-dimensional anatomy of the posterior pelvic ring pertinent to S1 and S2 iliosacral screw placement. Safety of simulated S1 iliosacral screw placement using different lateral ilium starting points. RESULTS: The transversely placed (horizontal) iliosacral screw was the least safe of the screws tested. The safest lateral ilium starting point for our entire population was at the posterior sacral body sagittally and at the inferior S1 foramen coronally. S2 iliosacral screws had less cross-sectional area for placement than S1 screws. Placement of the S2 screw slightly to the S1 foraminal side of the S2 vertebral body increased the safety of placement. CONCLUSION: The iliosacral screw starting point at the posterior sacral body and inferior S1 foramen was the safest when considering the entire population. Careful attention to the size and orientation of the S2 vertebral body should be taken if S2 iliosacral screws are placed.     

Vertically unstable pelvic fractures fixed with percutaneous iliosacral screws: does posterior injury pattern predict fixation failure?

OBJECTIVE: To measure the failure rate of percutaneous iliosacral screw fixation of vertically unstable pelvic fractures and particularly to test the hypothesis that fixations in which the posterior injury is a vertical fracture of the sacrum are more likely to fail than fixations with dislocations or fracture-dislocations of the sacroiliac joint. DESIGN: Retrospective review. SETTING: Level 1 trauma center. METHODS: All patients with pelvic fractures admitted between January 1, 1993, and December 31, 1998, were identified from the trauma registry. Hospital records were used to identify patients treated with iliosacral screws. Radiologic studies were examined to identify patients who had unequivocally vertically unstable pelvic fractures. Immediate postoperative and follow-up anteroposterior, inlet, and outlet radiographs from a minimum of 12 months postinjury were examined. Position, length, and numbers of iliosacral screws and any evidence of screw failure (eg, bending or breakage) were recorded. Residual postoperative displacement and late displacement of the posterior pelvis were measured. The main outcome measure was failure, defined as at least 1cm of combined vertical displacement of the posterior pelvis compared with immediate postoperative position. The main analysis was for association between fracture pattern and failure. Patient demographic data, iliosacral screw position, and anterior pelvic fixation method also were studied. RESULTS: The study group comprised 62 patients with unequivocally vertically unstable pelvic fractures in whom the posterior injury was treated with closed reduction and percutaneous iliosacral screw fixation. Of patients, 32 had dislocations or fracture-dislocations of the sacroiliac joint, and 30 had vertical fractures of the sacrum. Fixation failed in four patients, all with vertical sacral fractures and all within the first 3 weeks after surgery. These four patients required revision fixation. In two further cases with vertical sacral fractures, there was evidence that the fracture had only barely been held by the fixation, but these fractures healed, and follow-up radiographs did not meet the displacement criteria for failure. A vertical sacral fracture pattern was associated significantly with failure (Fisher exact test, P = 0.04); the excess risk of failure compared with sacroiliac joint injury was 13% (95% confidence interval 1% to 25%). There was no significant association between failure and anterior fixation method, iliosacral screw arrangement or length, or any demographic or injury variable. CONCLUSIONS: Percutaneous iliosacral screw fixation is a useful technique in the management of vertically unstable pelvic fractures, but a vertical sacral fracture should make the surgeon more wary of fixation failure and loss of reduction.     

Minimally invasive transiliac anatomical locking plate for posterior pelvic ring injury: A technical trick of the gull wing plate

Posterior pelvic ring injuries commonly involve sacral fractures, which are difficult to reduce and stabilize. Because conservative treatment requires long-term bedrest and leads to unsatisfactory outcomes, surgical intervention is a beneficial option to protect neurological structures and provide sufficient stability for early mobilization. Several studies have investigated a variety of internal fixation techniques, such as iliosacral screws, transiliac bars, spinal instruments, and transiliac plates. The gull wing plate (GWP) is a pre-contoured anatomical locking plate with two cancellous screws (φ6.5 mm) and four locking screws (φ5.0 mm), the design of which is unique among posterior tension-band plates. The GWP provides reliable stability of the posterior construct of the pelvic ring and accelerates rehabilitation. Compared to alternative surgical techniques for posterior fixation, the simple surgical procedure of the GWP is minimally invasive and highly reproducible, which leads to fewer complications and less radiation exposure.     

Unilaterale trianguläre lumbopelvine Stabilisierung

Operative fixation has become treatment of choice for unstable sacral fractures. Osteosynthesis for these fractures results in loss of reduction in up to 15%. Vertical sacral fractures involving the S1 facet joint (Isler 2 and 3) may lead to multidirectional instability. Multidirectional instability of the posterior pelvic ring and lumbopelvic junction may be stabilized and forces balanced by a so-called lumbopelvic triangular fixation. Lumbopelvic triangular fixation combines vertical fixation between the lumbar vertebral pedicle and the ilium, with horizontal fixation, as an iliosacral screw or a transiliacal plate osteosynthesis. The iliac screw is directed from the posterior superior iliac spine (PSIS) to the anterior inferior iliac spine (AIIS). Thereby, lumbopelvic fixation decreases the load to the sacrum and SI joint and transfers axial loads from the lumbar spine directly onto the ilium. Triangular lumbopelvic fixation allows early full weight bearing and therefore reduces prolonged immobilization. The placement of iliac screws may be a complex surgical procedure. Thus, the technique requires thorough surgical preparation and operative logistics. Wound-related complications may occur. Preexisting Morell–Lavalée lesions increase the risk for infection. Prominent implants cause local irritation and pain. Hardware prominence and pain are markedly reduced with screw head recession into the PSIS.     

Percutaneous transiliac pelvic fracture fixation: cadaver feasibility study and preliminary clinical results

BACKGROUND: Insertion of iliosacral lag screws into the S1 vertebral body has been well described in the literature. In situations in which the patient's S1 body morphology precludes the safe use of iliosacral screws, alternative implants have been suggested. The purpose of this study was to evaluate the feasibility of percutaneous transiliac pelvic fracture fixation as a treatment alternative. METHODS: First, three human cadaver torsos were examined to define the fluoroscopic anatomic parameters of the posterior iliac wing. Landmarks were identified to localize the potential initial implant insertion point for safe percutaneous placement of implants posterior to the spinal canal at the level of the posterior superior iliac spine. Next, a series of 10 clinical cases was used for an initial evaluation of a technique based on these findings, employing a cannulated, self-locking, transiliac screw. The pelvic injuries were type C in nine patients (OTA 61-C1 in seven, 61-C2 in one, and 61-C3 in one) and type B (OTA 61-B2) in one. RESULTS: Anatomic dissection of the cadavers with direct measurements and fluoroscopic imaging indicated that a percutaneous technique was feasible for transiliac pelvic fixation. The initial clinical series provided support for the described technique as determined from the cadaver-derived data. In these 10 cases, there were no untoward intraoperative events. Follow-up to union (minimum, 5 months) revealed no hardware failures. CONCLUSIONS: Percutaneous transiliac pelvic fixation is a feasible technique that may be considered by the pelvic surgeon pending further clinical study.     

Percutaneous stabilization of U-shaped sacral fractures using iliosacral screws: technique and early results

PURPOSE: To present the technique and early results of percutaneous stabilization of U-shaped sacral fractures with attention to neurologic recovery and maintenance of fracture reduction of the sacrum. DESIGN: Retrospective clinical study. SETTING: Level I trauma center. PATIENTS: During a thirty-eight-month period, 442 patients with pelvic ring disruptions were treated at a Level I trauma center. Thirteen (2.9 percent) of these patients had displaced U-shaped sacral fractures treated with percutaneous stabilization. INTERVENTION: Fracture stabilization was accomplished using fluoroscopically guided iliosacral screws inserted percutaneously with the patient positioned supine. Neurodiagnostic monitoring was not used during screw insertions. This technique was limited to patients with sacral kyphotic deformities, which allowed in situ fixation. Sacral neurologic decompression was not performed. MAIN OUTCOME MEASUREMENTS: Fracture healing and the stability of fixation were assessed on inlet and outlet radiographs and a lateral sacral view. Detailed neurologic examinations were performed at injury and at follow-up. RESULTS: The sacral fractures were classified based on plain pelvic radiographs and computed tomography scans and included one Type 1, eight Type 2, and four Type 3 fracture patterns. Twenty-five fully threaded cancellous 7.0-millimeter cannulated screws were used. Eleven patients had bilateral screw fixations; one patient had unilateral double screw fixation; and one patient had unilateral single screw fixation. Operative time for screw insertion averaged forty-eight minutes, with 2.1 minutes of fluoroscopy per screw. Accurate screw insertions without neuroforaminal or sacral spinal canal violations were confirmed in all patients with postoperative pelvic plain radiographs and computed tomography scans. A paradoxical inlet view of the upper sacral segments on the injury anteroposterior pelvis was seen in twelve of thirteen patients (92.3 percent), and the diagnosis was confirmed with the lateral sacral view in all thirteen (100 percent) patients. Preoperatively, sacral kyphosis averaged 29 degrees, whereas postoperative sacral kyphosis averaged 28 degrees. Screw disengagement occurred without a change in position of the sacral fracture in the only patient treated with a single unilateral screw. All fractures healed clinically and radiographically. Of the nine patients with preoperative neurologic abnormalities, two (22 percent) patients had residual neurologic deficits. Both patients had associated multiple level lumbar burst fractures, which required decompression and instrumented stabilization. CONCLUSIONS: These sacral fractures are rare and occur after significant spinal axial loading. A paradoxic inlet view of the upper sacrum on the anteroposterior plain pelvic radiograph heralds the diagnosis. Delayed diagnosis is avoided by a high clinical suspicion, early lateral sacral radiographs, and pelvic computed tomography scans. Surgical stabilization may assist in early mobilization of the patient from recumbency and prevents progressive deformity with associated nerve root injury. Percutaneous fixation diminishes potential blood loss and operative times, yet still allows subsequent sacral decompression of the local neural elements using open techniques when necessary. Early percutaneous iliosacral screw fixation is effective treatment for these injuries.     

Biomechanical comparison of posterior pelvic ring fixation

OBJECTIVE: To determine relative stiffness of various methods of posterior pelvic ring internal fixation. DESIGN: Simulated single leg stance loading of OTA 61-Cl.2, a2 fracture model (unilateral sacroiliac joint disruption and pubic symphysis diastasis). SETTING: Orthopaedic biomechanic laboratory. OUTCOME VARIABLES: Pubic symphysis gapping, sacroiliac joint gapping, hemipelvis coronal plane rotation. METHODS: Nine different posterior pelvic ring fixation methods were tested on each of six hard plastic pelvic models. Pubic symphysis was plated. The pelvic ring was loaded to 1000N. RESULTS: All data were normalized to values obtained with posterior fixation with a single iliosacral screw. The types of fixation could be grouped into three categories based on relative stiffness of fixation: For sacroiliac joint gapping, group 1-fixation stiffness 0.8 and above (least stiff) includes a single iliosacral screw (conditions A and J), an isolated tension band plate (condition F), and two sacral bars (condition H); group 2-fixation stiffness 0.6 to 0.8 (intermediate stiffness) includes a tension band plate and an iliosacral screw (condition E), one or two sacral bars in combination with an iliosacral screw (conditions G and I); group 3-fixation stiffness 0.6 and below (greatest stiffness) includes two anterior sacroiliac plates (condition D), two iliosacral screws (condition B), and two anterior sacroiliac plates and an iliosacral screw (condition C). For sacroiliac joint rotation, group 1-fixation stiffness 0.8 and above includes a single iliosacral screw (conditions A and J), two anterior sacroiliac plates (condition D), a tension band plate in isolation or in combination with an iliosacral screw (conditions E and F), and two sacral bars (condition H); group 2-fixation stiffness 0.6 to 0.8 (intermediate level of instability) includes either one or two sacral bars in combination with an iliosacral screw (conditions G and I); group 3-fixation stiffness 0.6 and below (stiffest fixation) consists of two iliosacral screws (condition B) and two anterior sacroiliac plates and an iliosacral screw (condition C). DISCUSSION: Under conditions of maximal instability with similar material properties between specimens, differences in stiffness of posterior pelvic ring fixation can be demonstrated. The choice of which method to use is multifactorial.     

Delayed posterior internal fixation of unstable pelvic fractures

Fifteen patients with unstable pelvic fractures were treated with immediate anterior external fixation followed by delayed posterior fixation, including five sacroiliac lag screws, six transiliac rods, and four iliac plates. Initial anterior external fixation aided in resuscitation of hemodynamically unstable patients and allowed early mobilization. Delayed posterior internal fixation avoided infection and hemorrhage but failed to achieve anatomic reduction of disrupted sacroiliac joints and sacral fractures. Followup examination confirmed maintenance of fixation and fracture healing but pain and persistent neurologic deficits were common findings. Lumbosacral nerve plexus injuries occurred in patients with fractures through the sacral foramina. Fixation of these fractures with sacroiliac screws and transiliac rods caused overcompression and the resulting foraminal encroachment may be a factor in the lack of neurologic recovery. In this study, delayed posterior internal fixation was not associated with perioperative morbidity and achieved better reductions than those obtained with external fixation alone. Delaying the fixation, however, increased the difficulty of obtaining anatomic reduction of certain posterior arch disruptions.     

Iliosacral screw fixation of the posterior pelvic ring using local anaesthesia and computerised tomography

Various techniques have been used for the fixation of the posterior pelvis, each with disadvantages specific to the technique. In this study, a new protocol involving the placement of posterior pelvic screws in the CT suite is described and evaluated. A total of 66 patients with unstable pelvic ring injuries was stabilised under local anaesthesia with sedation. The mean length of time for the procedure was 26 minutes per screw. There were no technical difficulties or misplaced screws and no cases of infection or nonunion. All patients stated that they would choose to have the CT scan procedure again rather than a procedure requiring general anaesthesia. The charges for the procedure were approximately 1840 pounds sterling (2800 dollars) per operation. CT-guided placement of iliosacral screws is a safe, feasible, and cost-effective alternative to radiologically-guided placement in the operating theatre in selected patients.     

Effect of pin location on stability of pelvic external fixation

Pelvic external fixators allow two locations of pin purchase: anterosuperior (into the iliac crest) and anteroinferior (into the supraacetabular dense bone, between the anterior superior and anterior inferior iliac spine). The purpose of this study was to compare the stability of these two methods of fixation on Tile Type B1 (open book) and C (unstable) pelvic injuries. Five unembalmed cadaveric pelves (mean age, 68 years; four males and one female) were loaded vertically in a servohydraulic testing machine in a standing posture. The AO tubular system and Orthofix were used. On each pelvis, a Type B1 injury was simulated. Each external fixator was applied in each location in random order. Cyclic loads were applied through the sacral body to a maximum of approximately 200 N while force and displacement of the pelvic ring were recorded digitally. Sacroiliac joint motion was quantified tridimensionally with displacement transducers, mounted on the sacrum and contacting a target fixed to the posterior superior iliac spine. A Type C injury was created and augmented with two iliosacral lag screws, and the tests were repeated. For the Type B1 injuries with anteroinferior pin purchase, the mean stiffness was 201.2 N/mm for the AO frame and 203.2 N/mm for the Orthofix. For the anterosuperior frames the mean stiffness was 143.9 N/mm for the AO frame and 163.3 N/mm for the Orthofix. For Type B1 and Type C injuries, the anteroinferior location of pin purchase resulted in significantly reduced sacroiliac joint separation. There were no significant differences between the frame types. Dissection of the preinserted anatomic specimen revealed no evidence of injury to the lateral femoral cutaneous nerve after blunt dissection and drilling with protective drill sleeves. It is concluded that the anteroinferior location of external fixation pins is a safe technique with the potential for increased stability of fixation.     

仰卧位经皮骶髂置钉固定术治疗骨盆后环损伤

目的 探讨仰卧位经皮骶髂置钉固定术治疗骨盆后环损伤的可行性、手术方法及疗效.方法 在10具尸体操作的基础上,2004年10月至2007年10月对14例骨盆后环损伤行仰卧位经皮骶髂置钉固定术.男7例,女7例;年龄28～75岁,平均41.6岁.Tile B型损伤4例,C型损伤10例.患者仰卧位,于"C"型臂X线机透视下以髂前上棘上2 cm与腋后线交点及髂前上棘与髂后上棘连线中、后1/3交点为进钉点,若两点距离较大,则在透视下确定最佳进钉点.进钉角度为向前20°～30°角,向尾端倾斜5°～15°.经皮骶髂置入一枚直径7.2 mm空心钛螺钉固定.术后摄骨盆正位、骶骨侧位X线片,并行骶髂关节CT扫描,观察螺钉在S1椎体的位置.结果 14例均获随访,平均随访16个月.术后3个月骨盆骨折均临床愈合.14例共置入15枚空心钛螺钉,未发生与置钉有关的并发症.随访期间无神经损伤、螺钉松动及断裂现象,无骨盆畸形及骶髂部疼痛.Majeed疗效评定标准优良率为92.9%.结论 采用体表双定位法,可提高仰卧位骶髂置钉固定术的安全性;仰卧位经皮骶髂置钉固定术治疗骨盆后环损伤方便、可行.     

Technique for percutaneous iliosacral screw insertion with conventional C-arm radiography

BACKGROUND: During percutaneous iliosacral screw fixation, fluoroscopy with a conventional C-arm X-ray unit is still the standard procedure for intraoperative orientation. Lateral sacral images in combination with the inlet and outlet view are always necessary. Nevertheless, the complex pelvic anatomy makes it difficult to prevent malpositioning of screws. OPERATIVE TECHNIQUE: Defining the correct entry into the bone is the decisive step for ideal screw placement. The better this is defined, the larger safety margins will be concerning cortical perforation by the screws. In the lateral view, an entry ventral to the sacral canal has to be avoided as well as an entry into the cranial half of the first sacral vertebra. To improve the surgeon's three-dimensional orientation with the help of his personal experience and two-dimensional images, it is recommended to place the tip of the screws in the center of the sacrum (in AP view) whenever possible. Routinely performed postoperative CT imaging of 24 screws, consecutively implanted according to the standards described, revealed no case of malpositioning. CONCLUSION: Standard X-ray views in combination with standardized aiming of screw entry position and final screw thread position enable the surgeon to find the "safe zone" for iliosacral screw insertion and to prevent iliosacral screw malpositioning with high accuracy.     

S2 iliosacral screw fixation for disruptions of the posterior pelvic ring: a report of 49 cases

OBJECTIVES: The purpose of this study was to evaluate the clinical safety and efficacy of using S2 iliosacral screws for pelvic fracture fixation. DESIGN: Retrospective analysis of a treatment protocol in a consecutive patient series. SETTING: Level 1 trauma center. PATIENTS: Between 1996 and 2001, 49 patients were treated with S2 iliosacral screws. There were 9 bilateral injuries with a total of 53 S2 screws inserted. Patients ranged in age from 14 to 71 years. Follow-up averaged 19 months (range 6 months to 6 years). Preoperative and postoperative radiographic evaluation included anteroposterior, inlet and outlet pelvic x-rays and two-dimensional computerized tomography (CT) with 3-mm slice thickness. Candidates for S2 screw fixation required adequate space on CT, which was defined as a minimum of 1 cm between foramina on 3 sequential preoperative CT slices in conjunction with inadequate available space in S1. INTERVENTION: S2 iliosacral screw fixation of disruptions of the posterior pelvic ring. MAIN OUTCOME MEASUREMENTS: Intraoperative iatrogenic nerve root injuries, postoperative screw position, and maintenance of the fixation construct under physiologic load. RESULTS: There were no intraoperative iatrogenic nerve injuries. However, postoperative loss of reduction requiring revision surgery occurred in 2 patients with osteopenia. One was associated with injury to the S1 nerve root, which had full return of function within 1 year. Satisfactory screw position was documented on postoperative CT in all cases. CONCLUSIONS: S2 iliosacral screw fixation is a safe and effective technique. However, it should be used with caution in patients with suspected pelvic osteopenia. Furthermore, any S2 screw with questionable purchase should be removed and an alternative fixation method selected.     

标准骶骨侧位像上骶神经根管前缘线对置入骶髂螺钉的作用

目的：了解骶神经根管于S1、S2骶段内的方位、走行,探讨标准骶骨侧位像上骶神经根管前缘线对置入骶髂螺钉的作用.方法：将全骨盆2.0 mm层厚轴向平扫数据导入到Mimics 10.0,并应用其分别将骶骨、双侧无名骨、骶管及骶神经根管制作成3D图像并旋转至标准骶骨侧位及骨盆出入口位后观察骶神经根管的方位、走行.辨识标准骶骨侧位及骨盆出入口位X线片上骶神经根管并观察其特点.结果：在S1、S2骶段内骶神经根管始于同节段椎管的头端前缘的两侧,止于同节段骶前孔,其走行由头端、后方、内侧至尾端、前方、外侧;在X线片上其密度低,尤其在标准骶骨侧位像上常仅其前缘线显像且多有中断现象而需要仔细辨识.结论：在标准骶骨侧位像上辨识骶神经根管前缘线并以之作为骶髂螺钉安全通道的尾后界,则可以避免内置物进入神经根管及骶管,从而提高置钉的安全性.