Finite element method (FEM) was used to investigate the biomechanical properties of three types of surgical fixations of U-shaped sacral fractures. Based on a previously established and validated complete lumbar-pelvic model, three models of surgical fixations of U-shaped sacral fractures were established: ① S1S2 passed through screw (S1S2), ② L4-L5 pedicle screw + screw for wing of ilium (L4L5 + IS), and ③ L4-L5 pedicle screw + S1 passed through screw + screw for wing of ilium (L4L5 + S1 + IS). A 400 N force acting vertically downward, along with torque of 7.5 N·m in different directions (anterior flexion, posterior extension, axial rotation, and axial lateral bending), was exerted on the upper surface of L4. Comparisons were made on differences in separation of the fracture gap and maximum stress in sitting and standing positions among three fixation methods. This study showed that: for values of separation of the fracture gap produced by different operation groups in different positions, L4L5 + S1 + IS was far less than L4L5 + IS and S1S2. For internal fixators, the maximum stress value produced was: L4L5 + IS > L4L5 + S1 + IS > S1S2. For the intervertebral disc, the maximum stress value produced by S1S2 is much larger than that of L4L5 + S1 + IS and L4L5 + IS. In a comprehensive consideration, L4L5 + S1 + IS could be prioritized for fixation of U-shaped sacral fractures. The objective of this research is to compare the biomechanical differences of three different internal fixation methods for U-shaped sacral fractures, for the reference of clinical operation.
Biomechanical Phenomena ; Finite Element Analysis ; Fracture Fixation ; methods ; Humans ; Lumbar Vertebrae ; Pedicle Screws ; Sacrum ; injuries ; Spinal Fractures ; surgery ; Spinal Fusion

BACKGROUNDResection of sacral chordomas is challenging. The anatomy is complex, and there are often no bony landmarks to guide the resection. Achieving adequate surgical margins is, therefore, difficult, and the recurrence rate is high. Use of computer navigation may allow optimal preoperative planning and improve precision in tumor resection. The purpose of this study was to evaluate the safety and feasibility of computer navigation-aided resection of sacral chordomas.

METHODSBetween 2007 and 2013, a total of 26 patients with sacral chordoma underwent computer navigation-aided surgery were included and followed for a minimum of 18 months. There were 21 primary cases and 5 recurrent cases, with a mean age of 55.8 years old (range: 35-84 years old). Tumors were located above the level of the S3 neural foramen in 23 patients and below the level of the S3 neural foramen in 3 patients. Three-dimensional images were reconstructed with a computed tomography-based navigation system combined with the magnetic resonance images using the navigation software. Tumors were resected via a posterior approach assisted by the computer navigation. Mean follow-up was 38.6 months (range: 18-84 months).

RESULTSMean operative time was 307 min. Mean intraoperative blood loss was 3065 ml. For computer navigation, the mean registration deviation during surgery was 1.7 mm. There were 18 wide resections, 4 marginal resections, and 4 intralesional resections. All patients were alive at the final follow-up, with 2 (7.7%) exhibiting tumor recurrence. The other 24 patients were tumor-free. The mean Musculoskeletal Tumor Society Score was 27.3 (range: 19-30).

CONCLUSIONSComputer-assisted navigation can be safely applied to the resection of the sacral chordomas, allowing execution of preoperative plans, and achieving good oncological outcomes. Nevertheless, this needs to be accomplished by surgeons with adequate experience and skill.

Adult ; Aged ; Aged, 80 and over ; Chordoma ; surgery ; Female ; Humans ; Imaging, Three-Dimensional ; Male ; Middle Aged ; Sacrum ; surgery ; Spinal Neoplasms ; surgery ; Surgery, Computer-Assisted ; methods ; Treatment Outcome

OBJECTIVETo evaluate the clinical effects of CT-guided percutaneous puncture and local chemotherapy for lumbosacral spinal tuberculosis.

METHODSFrom January 2002 to March 2013, 145 patients (84 males and 61 females) with lumbosacral spinal tuberculosis underwent failed conservative treatment were treated with CT-guided minimally invasive surgery. Their clinical data were retrospectively analyzed. Among them, 143 patients were followed up, aged from 2.5 to 81 years with an average of (42.60 +/- 17.14) years. Fourteen cases (6 cases with internal fixation and 8 cases without internal fixation) recurred and 32 cases complicated with paraspinal abscess after operation. Preoperatively 1 case complicated with lower limb weakness and superficial sensation worse, 1 case with muscle strength decrease, this 2 cases were grade D of Frankle, other cases were grade E. And 1 patient underwent fenestration operation and local chemotherapy, 144 cases with CT-guided percutaneous puncture and local chemotherapy. ESR and lumbar lordosis angle of all patients were observed preoperatively and final follow-up.

RESULTSThe mean follow-up time was 67 months (ranged, 21 to 149 months) in 143 cases, and 73 cases more than 5 years. All patients obtained clinical healing. ESR was (44.96 +/- 12.41) mm/h before operation and (7.25 +/- 3.43) mm/h at final follow-up, there was significant difference between preoperative and postoperative (t=35.06, P=0.000). Lumbar lordosis angle was (36.32 +/- 8.55) degrees before operation and (33.35 +/- 8.16) at final follow-up, there was significant difference between preoperative and postoperative (t=13.90, P=0.000).

CONCLUSIONWhen conservative treatment fails for 3 months or more, the patients have good spinal stabilization, nerve function is more than grade D of Frankel, CT-guided percutaneous puncture and local chemotherapy can get satisfactory outcomes for lumbosacral spinal tuberculosis.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; Debridement ; Female ; Humans ; Lumbosacral Region ; diagnostic imaging ; surgery ; Male ; Middle Aged ; Minimally Invasive Surgical Procedures ; Retrospective Studies ; Sacrum ; surgery ; Tomography, X-Ray Computed ; Tuberculosis, Spinal ; diagnostic imaging ; surgery ; Young Adult

OBJECTIVETo evaluate the clinical effects of iliolumbar fixation for the sacrum fractures of Denis type II.

METHODSThe clinical data of 86 patients with sacrum fracture of Denis type II treated by iliolumbar fixation from January 2008 to January 2012 were retrospectively analyzed. There were 55 males and 31 females, aged from 17 to 55 years old with an average of 39.1 years. Among them, 73 cases complicated with pelvis fracture and 13 cases with acetabular fracture; 37 cases with sacral neurological symptoms and 49 cases without sacral neurological symptoms. Fracture healing time, nerve function, clinical function and complications were observed in the patients.

RESULTSIn 86 cases, 6 cases were out of followed-up and 80 cases were followed up from 24 to 71 months with an average of 36 months. The mean fracture healing time was 13 weeks (ranged, 10 to 38 weeks). According to Gibbons scoring to evaluate the neurological function, preoperative nerve rehabilitation, lower limbs feeling, lower limbs activity,bladder and rectum function,total score respectively were 0.62 +/- 0.04, 1.54 +/- 0.35, 1.12 +/- 0.18, 0.23 +/- 0.01, 3.46 +/- 0.47 and postoperative respectively were 0.82 +/- 0.12, 0.36 +/- 0.04, 0.05 +/- 0.01, 0.03 +/- 0.01, 1.25 +/- 0.22, there were statistically significant differences between preoperative and postoperative (P < 0.05). According to Majeed scoring to evaluate the clinical function, postoperative pain, standing, sitting, sexual life, work ability, total score respectively were 22.54 +/- 4.02, 27.93 +/- 5.46, 8.47 +/- 3.61, 2.54 +/- 1.33, 16.46 +/- 4.34, 81.32 +/- 8.73, 60 cases got excellent results, 17 good, 3 fair. The main complications including fracture nonunion of 5 cases,deep incision infection of 1 case, and screw prominence resulting uncomfortable of 8 cases.

CONCLUSIONIliolumbar fixation has the advantages of stable fixation, satisfactory functional rehabilitation, less complications, and is a good method in treating sacrum fracture of Denis type II.

Adolescent ; Adult ; Bone Screws ; Female ; Fracture Fixation, Internal ; Humans ; Male ; Middle Aged ; Retrospective Studies ; Sacrum ; injuries ; surgery ; Spinal Fractures ; surgery ; Treatment Outcome ; Young Adult

BACKGROUNDA quantitative and accurate measurement of the range of hip joint flexion (RHF) is necessarily required in the evaluation of disordered or artificial hip joint function. This study aimed to assess a novel method to measure RHF more accurately and objectively.

METHODSLateral radiographs were taken of 31 supine men with hip joints extended or flexed. Relevant angles were measured directly from the radiographs. The change in the sacrofemoral angle (SFA) (the angle formed between the axis of the femur and the line tangent to the upper endplate of S1) from hip joint extension to hip joint flexion, was proposed as the RHF. The validity of this method was assessed via concomitant measurements of changes in the femur-horizontal angle (between the axis of the femur and the horizontal line) and the sacrum-horizontal angle (SHA) (between the line tangent to the upper endplate of S1 and the horizontal line), the difference of which should equal the change in the SFA.

RESULTSThe mean change in the SFA was 112.5 ± 7.4°, and was independent of participant age, height, weight, or body mass index. The mean changes in the femur-horizontal and SHAs were 123.0 ± 6.4° and 11.4 ± 3.0°, respectively. This confirmed that the change of SFA between hip joint extension and hip joint flexion was equal to the difference between the changes in the femur-horizontal and SHAs.

CONCLUSIONSUsing the SFA, to evaluate RHF could prevent compromised measurements due to the movements of pelvis and lumbar spine during hip flexion, and is, therefore, a more accurate and objective method with reasonable reliability and validity.

Adult ; Hip Joint ; diagnostic imaging ; surgery ; Humans ; Male ; Radiography ; Range of Motion, Articular ; physiology ; Sacrum ; diagnostic imaging ; surgery ; Young Adult

OBJECTIVETo evaluate the erectile and ejaculatory function of sacral tumor patients after sacral nerve root resection and investigate the relationship of erectile and ejaculatory dysfunction (EED) with the level of sacral nerve injury.

METHODSThis retrospective study included 47 male patients aged 16 to 63 (32.6 +/- 6.8) years treated by sacral tumor resection between January 2008 and August 2013. According to the levels of the sacral nerve roots spared in surgery, the patients were divided into four groups: bilateral S1-S3 (n=16), unilateral S1-S3 (n=21), unilateral S1-S2 (n=6), and unilateral S1 (n=4). The patients were followed up for 12 to 41 (27.2 +/- 10.9) months by questionnaire investigation, clinic review, and telephone calls about their erectile and ejaculatory function at 3, 6 and 12 months after surgery and in August 2013.

RESULTSIn the bilateral S1-S3 group, the incidence rates of EED were 31.25% (5/16), 25% (4/16), and 12.5% (2/16) at 3, 6, and 12 months respectively after surgery, with recovery of erectile and ejaculatory function in August 2013. The incidence rates of EED in the unilateral S1-S3 group were 85.71% (18/21), 71.43% (15/21), 52.38% (11/21), and 42.86% (9/21) at 3, 6 and 12 months and in August 2013, respectively; those in the unilateral S1-S2 group were 100% (6/6), 83.33% (5/6), 83.33% (5/6), and 66.67% (4/6) at the four time points; and those in the unilateral S1 group were all 100% (4/4). No statistically significant differences were found in the incidence rate of EED among the patients of different ages or tumor types (P > 0.05).

CONCLUSIONThe incidence of postoperative EED in male patients treated by sacral tumor resection is closely related to the mode of operation. Sparing the S3 nerve root at least unilaterally in sacral tumor resection is essential for protecting the erectile and ejaculatory function of the patient.

Adolescent ; Adult ; Ejaculation ; physiology ; Erectile Dysfunction ; epidemiology ; etiology ; Female ; Humans ; Incidence ; Male ; Middle Aged ; Organ Sparing Treatments ; Peripheral Nervous System Neoplasms ; surgery ; Postoperative Complications ; epidemiology ; Postoperative Period ; Retrospective Studies ; Sacrum ; Spinal Nerve Roots ; injuries ; surgery ; Surveys and Questionnaires ; Young Adult

OBJECTIVETo introduce a technique pertaining to S2 iliosacral screw insertion.

METHODSThe screw pathway was first measured on the preoperative pelvic CT scan or the standard sacral lateral radiograph to make sure the existence of the "safe zone" in the S2 segment for screw insertion. Under general anesthesia, patients were positioned supine or prone, depending on the injury pattern of pelvic ring or associated injuries requiring concomitant operation. The operation field was routinely sterilized using iodine and subsequent alcohol solution and draped. The tip of a guide wire was inserted through a stab wound to the posterior outer iliac table, manipulated in the "safe zone" being enclosed by the anterior aspect of the S2 nerve root tunnel, the anterior aspect of the sacral vertebrae, and the inferior aspect of the S1 foramen under the guidance of the standard sacral lateral fluoroscopy, and then the tip was hammered one to two millimeters into the iliac cortex. The guide wire progressed along the trajectory between the inferior aspect of the S1 foramen and the superior aspect of the S2 foramen on the pelvic outlet fluoroscopic view, and then along the posterior to the anterior aspect of the S2 sacral vertebrae and alae on the pelvic inlet fluoroscopic view with a predetermined length. At that moment, in order to ensure the safety, another standard sacral lateral view was imaged to detect the guide wire's tip which should locate posterior to the anterior aspect of the sacral vertebrae and anterior to the anterior aspect of the S2 nerve root tunnel. Subsequently, the depth was measured, the trajectory was drilled and tapped, and the screw was inserted. Following the removal of the guide wire, the wound was irrigated and sutured.

RESULTSUtilizing this insertion technique, there were 30 S2 iliosacral screws in total being placed to stabilize the injured and unstable posterior pelvic ring in 27 patients. Each S2 screw was accompanied by an ipsilateral S1 screw. The S2 screw location was completely intraosseous in all patients, which was verified by postoperative pelvic outlet and inlet radiographs and CT scans. The insertion accuracy was 100 percent in the present series.

CONCLUSIONThe S2 iliosacral screw insertion technique is safe and reproducible to guide the placement of the S2 screw, enhancing the stability for the compromised posterior pelvic ring.

Adult ; Bone Screws ; Female ; Fractures, Bone ; surgery ; Humans ; Ilium ; injuries ; surgery ; Male ; Sacrum ; injuries ; surgery

OBJECTIVETo summarize the clinical characteristics of severe lumbar dysplastic spondylolisthesis, and to investigate the effectiveness of the posterior surgery including decompression, partial reduction with instrumentations and interbody fusion.

METHODSTwelve patients of severe lumbar dysplastic spondylolisthesis treated between March 2007 and February 2012 were studied retrospectively. Twelve patients include 10 female and 2 male patients with an average age of 10.7 years (9-17 years). All of their spondylolisthetic level was L5 vertebrae. None of them were effective after regular conservative treatment. Eleven of 12 patients were treated surgically through a posterior decompression and instrumented reduction. One case was treated by L5 vertebrectomy and reduction of L4 onto sacrum. Their levels of instrumentations were L4-S1 in 8 patients and L5-S1 in 4 patients. All of 12 patients were fused via interbody fusion. The visual analog scale(VAS), Oswestry disability index (ODI), Japanese Orthopaedic Association(JOA) score, slip angle, percentage slip, lumbar lordosis, sagittal balance were used as outcome measures.

RESULTSAll of these patients were followed up regularly with an average follow-up of 32 months (6-64 months). Five of these 12 patients suffered postoperative nerve root impairment, including impairment of unilateral and bilateral L5 nerve roots. At the latest follow-up, only 1 case was still suffering from the weakness of unilateral peroneal long and short muscles, the other 4 patients recovered totally. The degree of their spondylolisthesis was reduced II degrees or more, and their slip angles decreased from 35.6 degree preoperatively to 9.8 degree postoperatively. The VAS, ODI , JOA, lumbar lordosis and sagittal balance were improved postoperatively. No instrumentation loosening or rupture was found.

CONCLUSIONSIn patients with severe lumbar dysplastic spondylolisthesis, isolated posterior decompression, reduction with internal fixation may lead to a satisfactory clinical outcomes. Surgical reduction is helpful to improve the interbody contact area, thus possibly improve the fusion rate. At the same time, reduction may reduce or correct the lumbar-sacral kyphosis, recover the normal lumbar lordosis and normal sagittal alignment with an excellent cosmetic result. The incidence of the postoperative nerve impairment is high because of the stretching of L5 nerve roots secondary to the reduction, but most of the patients with postoperative nerve impairment may recover gradually.

Adolescent ; Child ; Decompression, Surgical ; Female ; Humans ; Lumbar Vertebrae ; surgery ; Lumbosacral Region ; Male ; Orthopedic Procedures ; methods ; Retrospective Studies ; Sacrum ; surgery ; Severity of Illness Index ; Spinal Fusion ; Spondylolisthesis ; surgery ; Treatment Outcome

OBJECTIVESTo introduce a classification system of upper sacral segment and its significance based on the continuous pelvic axial computed tomography scan.

METHODSThe whole pelvis 2.0 mm thick axial scan images of 127 cases were observed, the sacroiliac screw channel of S1 were measured, according to the size of the transverse screw channel the upper sacral segment were classified. Such as transverse screw channel existed and in at least 4 layer scan images its width was > 7.3 mm, it was defined as sacral segment of the normal type. Such as transverse screw channel existed and its maximum width was 7.3 mm or less on scanning level, it was defined as a transitional. Such as transverse channel did not exist, or its width on all scanning level was 0 mm or less, it was defined as dysplastic. Various cases,percentage, and the average of the transverse screw channel were calculated.

RESULTSThere were 58 normal (45.7%),42 transitional (33.1%), and 27 dysplastic (21.2%) upper sacral segments with an averaged width of the tansverse screw channel of 13.9 mm, 5.2 mm, and 0.9 mm, respectively. Each specimen could be defined as one of the three types of upper sacral segment without exceptions.

CONCLUSIONIt is possible to insert a transverse iliosacral screw into a normal upper sacral segment when indicated because of the capacious transverse screw channel. The transverse iliosacral screw placement into the transitional and dysplastic upper sacral segments was contraindicated because of the limited or none transverse screw channel. The transitional upper sacral segment was superior to the dysplastic segment due to its starting point location restriction on the true lateral sacral view.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Bone Density ; Bone Screws ; Female ; Fracture Fixation, Internal ; Humans ; Male ; Middle Aged ; Pelvic Bones ; diagnostic imaging ; surgery ; Sacrum ; diagnostic imaging ; surgery ; Tomography, X-Ray Computed ; Young Adult

OBJECTIVETo introduce the location and course of S1, S2 sacral nerve root tunnel and to clarify the significance of the anterior aspect of sacral nerve root tunnel on placement of iliosacral screw on the standard lateral sacral view.

METHODSFirstly the data of 2.0 mm slice pelvic axial CT images were imported into Mimics 10.0, and the sacrum, innominate bones, and sacral nerve root tunnels were reconstructed into 3D views respectively, which were rotated to the standard lateral sacral views, pelvic outlet and inlet views. Then the location and course of the S1, S2 sacral nerve root tunnel on each view were observed.

RESULTSThe sacral nerve root tunnel started from the cranial end and anterior aspect of the vertebral canal of the same segment and ended up to the anterior sacral foramen with a direction from cranial-posterior-medial to caudal-anterior-lateral. The tunnel had a lower density than the iliac cortex and greater sciatic notch on the pelvic X-rays,especially on the standard sacral lateral view, on which it showed up as a disrupted are line and required more careful recognition.

CONCLUSIONIt can prevent the iliosacral screw from penetrating the sacral nerve root tunnel and vertebral canal when recognizing the anterior aspect of sacral nerve root tunnel and choosing it as the caudal-posterior boundary of the "safe zone" on the standard lateral sacral view.

Adult ; Aged ; Bone Screws ; Female ; Fracture Fixation, Internal ; Fractures, Bone ; surgery ; Humans ; Male ; Middle Aged ; Pelvic Bones ; diagnostic imaging ; injuries ; innervation ; surgery ; Radiography ; Sacrococcygeal Region ; diagnostic imaging ; innervation ; surgery ; Sacrum ; diagnostic imaging ; injuries ; innervation ; surgery ; Spinal Nerve Roots ; diagnostic imaging ; surgery ; Young Adult