A novel approach to sagittal balance restoration following iatrogenic sacral fracture and resulting sacral kyphotic deformity

Incidence and Risk Factors of Sacral Fracture Following Lumbosacral Fusion for Degenerative Spinal Stenosis with a Minimum Follow-Up of 2 Years: A Case-Control Study

BACKGROUND

This study aimed to investigate the incidence and risk factors for sacral fractures following lumbosacral fusion.

METHODS

We conducted a retrospective review of patients who underwent lumbosacral fusion for degenerative spinal stenosis with a minimum follow-up of 2 years. Patients who developed and those who did not develop a sacral fracture were categorized into the "sacral fracture" and "nonfracture" groups. The demographic and radiological data were compared between the 2 groups.

RESULTS

A total of 65 patients were included in this study. Among them, 7 patients were categorized into the sacral fracture and 58 patients into the nonfracture groups, respectively. The incidence of sacral fracture was 10.8%. In the sacral fracture group, age and fusion levels were significantly higher (P<0.05), while bone mineral density (BMD) T-score was significantly lower (P<0.05) than nonfracture group. Pelvic incidence, preoperative pelvic tilt, postoperative sacral slope, and postoperative lumbar lordosis were significantly higher (P<0.05) in the sacral fracture than the nonfracture group. Multivariable logistic regression analysis showed that BMD T-score (odds ratio [OR] 0.25, 95% confidence interval [CI] 0.08-0.79, P = 0.019), postoperative sacral slope (OR 1.14, 95% CI 1.00-1.29, P = 0.047), and changes in L4-S1 lordosis (OR 1.11, 95% CI 1.00-1.23, P = 0.049) were significant factors.

CONCLUSIONS

The overall incidence of sacral fracture was 10.8%. In our study, advanced age, low BMD, long fusion levels, and preoperative compensatory pelvic retroversion and excessive correction of it were risk factors for sacral fractures.

Biomechanical evaluation of multi-rod constructs to stabilize an S1 pedicle subtraction osteotomy (PSO): a finite element analysis

PURPOSE

To develop and validate a finite element (FE) model of a sacral pedicle subtraction osteotomy (S1-PSO) and to compare biomechanical properties of various multi-rod configurations to stabilize S1-PSOs.

METHODS

A previously validated FE spinopelvic model was used to develop a 30° PSO at the sacrum. Five multi-rod techniques spanning the S1-PSO were made using 4 iliac screws and a variety of primary rods (PR) and accessory rods (AR; lateral: Lat-AR or medial: Med-AR). All constructs, except one, utilized a horizontal rod (HR) connecting the iliac bolts to which PRs and Med-ARs were connected. Lat-ARs were connected to proximal iliac bolts. The simulation was performed in two steps with the acetabula fixed. For each model, PSO ROM and maximum stress on the PRs, ARs, and HRs were recorded and compared. The maximum stress on the L5-S1 disc and the PSO forces were captured and compared.

RESULTS

Highest PSO ROMs were observed for 4-Rods (HR + 2 Med-AR). Constructs consisting of 5-Rods (HR + 2 Lat-ARs + 1 Med-AR) and 6-Rods (HR + 2 Lat-AR + 2 Med-AR) had the lowest PSO ROM. The least stress on the primary rods was seen with 6-Rods, followed by 5-Rods and 4-Rods (HR + 2 Lat-ARs). Lowest PSO forces and lowest L5-S1 disc stresses were observed for 4-Rod (Lat-AR), 5-Rod, and 6-Rod constructs, while 4-Rods (HR + Med-AR) had the highest.

CONCLUSION

In this first FE analysis of an S1-PSO, the 4-Rod construct (HR + Med-AR) created the least rigid environment and highest PSO forces anteriorly. While 5- and 6-Rods created the stiffest constructs and lowest stresses on the primary rods, it also jeopardized load transfer to the anterior column, which may not be favorable for healing anteriorly. A balance between the construct's rigidity and anterior load sharing is essential.

Sacral Pedicle Subtraction Osteotomy for Treatment of High-Grade Spondylolisthesis: A Technical Note and Review of the Literature

BACKGROUND

Lumbosacral deformities are caused by high-grade spondylolisthesis, fractures, iatrogenic flat back, and other etiologies. The S1 pedicle subtraction osteotomy (PSO) can facilitate reduction of spondylolisthesis and lower the pelvic incidence. There are limited reports on the indications and outcomes of this technique.

OBJECTIVE

To present a technical description and literature review of the S1 PSO with video summary.

METHODS

This was a retrospective review of a single case to highlight the use of S1 PSO for the treatment of high-grade spondylolisthesis. A literature review was performed in accordance with STROBE guidelines.

RESULTS

A 47-year-old woman presented with back and right leg pain related to grade 4 spondylolisthesis at L5-S1 with sagittal imbalance and lumbosacral kyphosis. She was taken for an L2-pelvis instrumented fusion with S1 PSO. Three days later, she was taken for an L4-5 and L5-S1 anterior lumbar interbody fusion with the L5-S1 segmental plate. Her postoperative course was notable for right foot drop that resolved in 6 weeks. Postoperative x-rays showed successful reduction of spondylolisthesis with normal alignment and sagittal balance. Based on 6 studies involving 22 true sacral PSOs in the literature, the procedure carries a 27% risk of neurological deficit, typically in the form of L5 palsy.

CONCLUSION

The S1 PSO is a technically challenging operation that has a unique role in the treatment of high-grade spondylolisthesis. It carries a significant risk of L5 palsy and should be reserved for surgeons with experience performing complex 3-column osteotomies.

Sacral Insufficiency Fracture Following Short-Segment Lumbosacral Fusion: Case Series and Review of the Literature

STUDY DESIGN

Retrospective case series.

OBJECTIVE

Sacral insufficiency fracture is a rare and serious complication following lumbar spine instrumented fusion. The purpose of this study was to describe the patient characteristics, presentation, evaluation, treatment options, and outcomes for patients with sacral insufficiency fracture after short-segment lumbosacral fusion.

METHODS

Six patients from our institutional database and 16 patients from literature review were identified with a sacral insufficiency fracture after short-segment (L4-S1 or L5-S1) lumbar fusion within 1 year of surgery.

RESULTS

Patients were 55% female with a mean age of 58 years and body mass index of 30 kg/m². Osteoporosis or osteopenia was the most common comorbidity (85%). Half of patients sustained a sacral fracture after surgery from a posterior approach, while the others had anterior or anterior-posterior surgery. Mean time to fracture was 42 days with patients clinically presenting with new sacral pain (86%), radiculopathy (60%), or neurologic deficit (5%). Ultimately, 73% of patients underwent operative fixation often involving extension of the construct (75%) and fusion to the pelvis (69%). Men (P = .02) and patients with new radicular pain or neurologic deficit (P = .01) were more likely to undergo revision surgical treatment while women over 50 years of age were more likely to be treated conservatively (P = .003).

CONCLUSIONS

Spine surgeons should monitor for sacral insufficiency fracture as a source of new-onset pain in the postoperative period in patients with a short segment fusion to the sacrum. The recognition of this complication should prompt an assessment of bone health and management of underlying bone fragility.

Jumper's fracture of the sacrum: a novel and reproducible way for successful reduction and fixation

PURPOSE

Surgical treatment of jumper's fractures is a highly demanding situation for the surgeon due to its rareness and frequent association with severe concomitant injuries. There is no current consensus regarding a standard treatment approach, thus reducing quality of care. Our objectives were to describe, apply and assess a novel surgical technic.

METHODS

The presented research is an observational retrospective study of patients who underwent the described novel surgical intervention in a level 1 trauma center. We conducted analyses of the patient cohort using patient-related outcome measures at least 1 year after surgery, as well as investigating pain, quality of life and the clinical effectiveness of the procedure.

RESULTS

A total of 24 patients (17 male and 7 female) with an average age 47 ± 16.3 years were included. ISS scores ranged from 9 to 66 with a mean ISS of 40 ± 15. Clinical scores exist of 15 out of 24 patients (62.5%). The mean VAS score was 53.7 ± 12.9. The mean EQ-5D index was 0.68 ± 0.22. Significant negative correlation existed between the ISS value and the EQ-5D index (r =  - 0.704; p < 0.005) and EQ-5D VAS (r =  - 0.809; p < 0.001). Anatomical reduction was achieved in all patients (n = 24). Radiological follow-up was performed in 58%.

CONCLUSION

We present one of the largest studies with operatively treated jumper's fractures of the sacrum. The technique is capable of reproducibly restoring the physiological anatomy of the patient and allows pain-adapted mobilization.

Lumbosacral osteotomy to correct PI-LL mismatch in the presence of abnormally high pelvic incidence

STUDY DESIGN

A case report. It is important to achieve optimal sagittal balance in spinal deformity surgery by matching LL to PI. A Lumbar osteotomy to increase lordosis is often the method used to achieve this in adult patients. However, in patients with high PI with compensatory lumbar hyperlordosis, providing further lordosis does not address the root cause. The paper will describe a technique of lumbosacral osteotomy to address sagittal malalignment with associated coronal imbalance and pelvic incidence (PI)-lumbar lordosis (LL) mismatch.

METHODS

A 16-year-old female patient presented with low back pain and right leg pain. Standing anteroposterior X-ray showed scoliosis with a Cobb angle of 34º and 5.7 cm of coronal imbalance. Lateral X-ray showed a sacralized L5 with a PI of 85º and LL of 47º. Pedicle subtraction osteotomy through the sacralized L5 addressed the malalignment secondary to a high PI-LL mismatch of 38º.

RESULTS

Following alar resection, an osteotomy was performed below the L5 pedicles. The cranial parts including the superior endplate and intervertebral disc were removed. Osteotomy closure was achieved using the central rod technique. L5 incidence was reduced from 59º to 33º with reduced coronal malalignment. Back pain was significantly improved and PI-LL mismatch was improved to 10º two years post-operatively with no local loss of sagittal correction.

CONCLUSIONS

A lumbosacral osteotomy at the lumbosacral junction is useful to improve high PI - LL mismatch in patients with abnormally high PI with compensatory lumbar hyperlordosis.

Complication profile associated with S1 pedicle subtraction osteotomy compared with 3-column osteotomies at other thoracolumbar levels for adult spinal deformity: series of 405 patients with 9 S1 osteotomies

OBJECTIVE

There is an increased recognition of disproportional lumbar lordosis (LL) and artificially high pelvic incidence (PI) as a cause for positive sagittal imbalance and spinal pelvic mismatch. For such cases, a sacral pedicle subtraction osteotomy (PSO) may be indicated, although its morbidity is not well described. In this study, the authors evaluate the specific complication risks associated with S1 PSO.

METHODS

A retrospective review of all adult spinal deformity patients who underwent a 3-column osteotomy (3CO) for thoracolumbar deformity from 2006 to 2019 was performed. Demographic, clinical baseline, and radiographic parameters were recorded. The primary outcome of interest was perioperative complications (surgical, neurological, and medical). Secondary outcomes of interest included case length, blood loss, and length of stay. Multivariate analysis was used to assess the risk of S1 PSO compared with 3CO at other levels.

RESULTS

A total of 405 patients underwent 3CO in the following locations: thoracic (n = 55), L1 (n = 25), L2 (n = 29), L3 (n = 141), L4 (n = 129), L5 (n = 17), and S1 (n = 9). After S1 PSO, there were significant improvements in the sagittal vertical axis (14.8 cm vs 6.7 cm, p = 0.004) and PI-LL mismatch (31.7° vs 9.6°, p = 0.025) due to decreased PI (80.3° vs 65.9°, p = 0.006). LL remained unchanged (48.7° vs 57.8°, p = 0.360). The overall complication rate was 27.4%; the surgical, neurological, and medical complication rates were 7.7%, 6.2%, and 20.0%, respectively. S1 PSO was associated with significantly higher rates of overall complications: thoracic (29.1%), L1 (32.0%), L2 (31.0%), L3 (19.9%), L4 (32.6%), L5 (11.8%), and S1 (66.7%) (p = 0.018). Similarly, an S1 PSO was associated with significantly higher rates of surgical (thoracic [9.1%], L1 [4.0%], L2 [6.9%], L3 [5.7%], L4 [10.9%], L5 [5.9%], and S1 [44.4%], p = 0.006) and neurological (thoracic [9.1%], L1 [0.0%], L2 [6.9%], L3 [2.8%], L4 [7.0%], L5 [5.9%], and S1 [44.4%], p < 0.001) complications. On multivariate analysis, S1 PSO was independently associated with higher odds of overall (OR 7.93, p = 0.013), surgical (OR 20.66, p = 0.010), and neurological (OR 14.75, p = 0.007) complications.

CONCLUSIONS

S1 PSO is a powerful technique for correction of rigid sagittal imbalance due to an artificially elevated PI in patients with rigid high-grade spondylolisthesis and chronic sacral fractures. However, the technique and intraoperative corrective maneuvers are challenging and associated with high surgical and neurological complications. Additional investigations into the learning curve associated with S1 PSO and complication prevention are needed.

Sacrum osteotomy to change pelvic parameters: Surgical technique and 3D modeling

PURPOSE

Some clinical situations, such as great sagittal imbalance, high-grade isthmic spondylolisthesis or sacral malunion could require a sacral osteotomy to decrease pelvic parameters, horizontalize the sacrum or correct sacral malunion. Here is described a novel technique to perform a sacral osteotomy to decrease pelvic parameters with a lumbo-pelvic construct, with first a sacral slope decrease, then a pelvic tilt decrease.

METHODS

Simulations have been performed using tridimensional reconstructions of the lumbar spine and pelvis, made from CT-scan images of a healthy individual. A cadaveric study has then been performed.

RESULTS

3D modeling exhibited linear relationship between osteotomy angle and pelvic incidence correction, through multiple simulations with 1° increment. Cadaveric study demonstrated feasibility.

CONCLUSION

This preliminary work shows that this technique is efficient to decrease pelvic parameters. A linear relationship has been exhibited between osteotomy angle and PI decrease, as per the following formula: osteotomy angle=PI change/0.84.

A Case Series That Supports the Application of the S2AI Technique for Fractures and Failures After Lumbosacral Fusion

BACKGROUND

Sacral fractures and failures are uncommon after lumbosacral fusion but have received increasing attention in the surgical literature. They can be difficult to diagnose, making timely treatment difficult. No consensus has been reached on the characteristics of these complications or on optimal treatment.

QUESTIONS/PURPOSES

The goal of this retrospective case series is to contribute additional cases of these uncommon complications of lumbosacral fusion to the surgical literature to help clinicians to anticipate, diagnose, characterize, manage, and treat sacral fractures and failures after lumbosacral fusion.

METHODS

The medical records of five patients who experienced a sacral fracture or failure after lumbosacral fusion between January 2012 and November 2017 were identified and reviewed retrospectively. Records were reviewed for age, sex, clinical presentation, previous management, outpatient clinical records, imaging, and post-operative course.

RESULTS

Four patients in the series experienced a sacral fracture and one experienced hardware failure. All patients presented with elevated pain and underwent revision surgery. Radiographic detection of the fracture or failure occurred at a mean of 11.2 weeks (range, 3 to 24 weeks) after initial surgery, and the mean age of patients was 68.2 years (range, 63 to 80 years). Of the five patients, four were female; two had been diagnosed with osteoporosis and two with osteopenia. In our case series, the S2-alar-iliac (S2AI) technique was used with success in all five cases.

CONCLUSION

Fractures and failures after lumbosacral fusion can be difficult to diagnose because of delayed presentation, nonspecific presenting symptoms, and a lack of identifiable mechanism. A high index of suspicion is required to detect these uncommon complications, and patients have responded well to both conservative and surgical treatments.

Clinical results and functional outcomes after three-column osteotomy at L5 or the sacrum in adult spinal deformity

PURPOSE

Three-column osteotomies at L5 or the sacrum (LS3COs) are technically challenging, yet they may be needed to treat lumbosacral kyphotic deformities. We investigated radiographic and clinical outcomes after LS3CO.

METHODS

We analyzed 25 consecutive patients (mean age 56 years) who underwent LS3CO with minimum 2-year follow-up. Standing radiographs and health-related quality-of-life scores were evaluated. A new radiographic parameter ["lumbosacral angle" (LSA)] was introduced to evaluate sagittal alignment distal to the S1 segment.

RESULTS

From preoperatively to the final follow-up, significant improvements occurred in lumbar lordosis (from - 34° to - 49°), LSA (from 0.5° to 22°), and sagittal vertical axis (SVA) (from 18 to 7.3 cm) (all, p < .01). Mean Scoliosis Research Society (SRS)-22r scores in activity, pain, self-image, and satisfaction (p < .05), and Oswestry Disability Index scores (p < .01) also improved significantly. Patients with SVA ≥ 5 cm at the final follow-up experienced less improvement in SRS-22r satisfaction scores than those with SVA < 5 cm. Patients with LSA < 20° at the final follow-up had significantly lower SRS-22r activity scores than those with LSA ≥ 20° (p = .014). Two patients had transient neurologic deficits, and 11 patients underwent revision for proximal junctional kyphosis (5), pseudarthrosis (3), junctional stenosis (2), or neurologic deficit (1).

CONCLUSIONS

LS3CO produced radiographic and clinical improvements. However, patients who remained sagittally imbalanced had less improvement in SRS-22r satisfaction score than those whose sagittal imbalance was corrected, and patients who maintained kyphotic deformity in the lumbosacral spine had lower SRS-22r activity scores than those whose lumbosacral kyphosis was corrected. These slides can be retrieved under Electronic Supplementary Material.

Importance of Spinal Alignment in Primary and Metastatic Spine Tumors

Spinal alignment, particularly with respect to spinopelvic parameters, is highly correlated with morbidity and health-related quality-of-life outcomes. Although the importance of spinal alignment has been emphasized in the deformity literature, spinopelvic parameters have not been considered in the context of spine oncology. Because the aim of oncologic spine surgery is mostly palliative, consideration of spinopelvic parameters could improve postoperative outcomes in both the primary and metastatic tumor population by taking overall vertebral stability into account. This review highlights the relevance of focal and global spinal alignment, particularly related to spinopelvic parameters, in the treatment of spine tumors.

The Use of Sacral Osteotomy in the Correction of Spinal Deformity: Technical Report and Systematic Review of the Literature

BACKGROUND

Flat back deformity is a disabling adverse outcome following instrumented lumbar fusion. As patients are often fused in this non-physiologic alignment, correction is complex and has conventionally required fracture of the preexisting fusion mass. Sacral osteotomy may be one effective means of correcting the positive sagittal balance in these patients. Here we report a case of flat back deformity corrected using a 3-column sacral osteotomy, and systematically review the available literature on the effectiveness of 3-column sacral osteotomy for correcting flat back deformity.

METHODS

A systematic review was performed using the results of a search of the PubMed, EMBASE, Web of Science, and Cochrane databases according to PRISMA guidelines. We also include our patient as an example of the technique.

RESULTS

Eight studies-all case reports or small case series-were identified describing 37 patients, including our case example. The variety of techniques was too heterogeneous for meta-analysis, but all studies reported good correction of sagittal deformity. Transient L5 palsy was the most common side effect of this technique, being reported in 21 patients (56.8%) across all studies.

CONCLUSIONS

Sacral osteotomy is potentially an effective means of correcting positive sagittal balance in patients with flat back deformity secondary to high pelvic incidence.

Extended L5 pedicle subtraction osteotomy for neglected sacropelvic dissociation injury: case report

The sacrum forms the distal end of the spine and communicates with the pelvis. Fractures involving the sacrum are complex and may disrupt this vital communication. Neglecting these fractures may result in malunion, which often causes significant alteration in the pelvic parameters and sagittal balance. Management of ensuing deformities is complex and poorly described. The authors present a case of sacral malunion with sagittal imbalance treated with a low lumbar osteotomy.

SACRAL FRACTURE TREATMENT WITH A VARIATION OF THE LUMBOPELVIC FIXATION TECHNIQUE

ABSTRACT Spinopelvic instability is an uncommon injury that is caused by high-energy traumas. Surgical treatment is used, in the majority of cases, to restore stability and enable early mobilization. Various stabilization techniques have been used in the treatment of spinopelvic instability, and lumbopelvic fixation (LPF) is currently the technique of choice due to its biomechanical superiority. One of its limitations is the fact that the technique does not directly address the lower sacral segment, permitting a residual kyphotic deformity. This deformity has been attributed to unsatisfactory outcomes, including late development of pelvic floor muscle defects and complications during childbirth. We report a case of a patient with spinopelvic instability due to sacral fracture, which was treated using a variation of the LPF technique, in which rods and screws originally developed for cervicothoracic fixation were adapted to correct sacral deformity in the sagittal plane. The upper sacral segment was reduced indirectly using hip extension and femoral traction manoeuvres, associated with distraction manoeuvres via rods. Bone reduction forceps were used to reduce the kyphotic deviation in the lower sacral fragment, enabling its fixation to the lumbopelvic rod and screws system. There were no complications of infection, suture dehiscence, or breakage of the implants, and at the end of the first year of follow-up, the sacral kyphosis was normal and radiographic consolidation was confirmed. Our technique provides a viable and promising alternative to traditional LPF, making it especially useful in fractures with accentuated deviations of the lower sacral fragment. Level of Evidence: 4.Type of study: Case series

Sacral pedicle subtraction osteotomy for an extreme case of positive sagittal balance: case report

The importance of sagittal spinal balance and lumbopelvic parameters is now well understood. The popularization of various osteotomies, including Smith-Peterson, Ponte, and pedicle subtraction osteotomies (PSOs), as well as vertebral column resections, have greatly enhanced the spine surgeon's ability to recognize and effectively treat sagittal imbalance. Yet rare circumstances remain, most notably in distal kyphotic deformities and patients with extremely elevated pelvic incidences, where these techniques remain inadequate. In this article, the authors describe a patient with severe sagittal imbalance despite multiple prior anterior and posterior reconstructive surgeries in which a sacral PSO was performed with good results. A description of this technique as well as a brief review of the literature is provided.

Reduction and fixation of displaced U-shaped sacral fractures using lumbopelvic fixation: technical recommendations

PURPOSE

U-shaped sacral fractures are extremely rare injuries that usually occur as a result of falls from considerable heights. Almost all treatment methods described to date aim solely at stabilizing the fracture but do not contribute to supporting the reduction of such fractures. Using existing implants the purpose of this study is to present a surgical technique that facilitates both the reduction and the stabilization of these injuries. The presented technique was evaluated in a series of three cases.

METHODS

Polyaxial pedicle screws were placed through vertebral bodies L4 and L5. Two long pedicle screws were implanted in the posterior iliac spine. The lumbar pedicle screws were held with two longitudinal rods, and the pelvic screws with one transverse connecting rod. The lumbar longitudinal and pelvic transverse rods were connected via two hinge-like connecting elements. First, distraction was performed between lumbar pedicle screws L5 and the sacral transverse rod. Lordosis was then restored via the hinge joint, thereby eliminating kyphosis. After tightening all moving elements, the fracture was reduced and stabilized.

RESULTS

Computed tomography documented anatomical reduction and fracture healing was achieved in all cases. Two of three patients could be fully mobilized immediately; mobilization of the third patient was delayed due to multiple injuries. Two patients showed neurological symptoms. In one case, complete remission was achieved within 3 weeks, while in the other patient a clear improvement was observed. In all cases, the implant was removed after 8-12 months. There were no post-operative complications, such as infections, wound-healing disorders, neurological deterioration, implant failure, or premature loosening.

CONCLUSIONS

The surgical procedure was successful, since it considerably facilitated reduction, thereby shortening surgery time. The stabilization was sufficient to fully mobilize the patients. The procedure is based on existing implant components and is thus routinely available.

Current concepts in spondylopelvic dissociation

INTRODUCTION

Spondylopelvic dissociation is an uncommon and complex injury that results from high-energy trauma with axial overloading through the sacrum. Due to the life-threatening nature of these injuries, standard Advanced Trauma Life Support^® (ATLS) protocol must be used in the trauma setting as part of the initial management of these patients. The key to diagnosis is a good physical exam coupled with high level of suspicion. Radicular neurological deficits commonly are present in spondylopelvic dissociation (L5's roots) and should be documented for future evaluations. Radiographic views and CT-scan is preferred for the diagnosis.

BIOMECHANICS AND CLASSIFICATION

The authors briefly describe the anatomy and biomechanics of the pelvis, and present the main classifications used to define this rare lesion.

TREATMENT

Discussion about setting the boundaries of surgical stabilization, if there is still a role for conservative treatment, the importance of the initial treatment and the timing of intervention. Decompression is mandatory in the presence of canal compromise and progressive neurological deficit, regardless of biomechanical criteria for surgery. Kyphotic deformity occurs at the site of sacral transverse fracture and also reduces anteroposterior pelvis diameter. The technique of reduction and posterior surgical stabilization is emphasized. If residual kyphosis remains after bilateral lumbopelvic fixation by shifting of the lower sacral segment, we use S2 and/or S3 screws connected to transitional rods to additional reduction. An illustrated case is shown.

COMPLICATIONS

The infection of the wound and the failure of the implants are the most frequent complications of this surgical treatment.

CONCLUSION

Posterior stabilization is widely recognized as crucial in the treatment of pelvic disruptions. The concept of circumferential restoration of pelvic ring by bilateral lumbopelvic fixation and anterior fixation seems to be a nice option to increase stabilization and avoid bone misalignment.

New method for correction of lumbo-sacral kyphosis deformity in patient with high pelvic incidence

STUDY DESIGN

Technical note.

OBJECTIVE

We describe a novel technique of bilateral longitudinal sacral osteotomy allowing direct reduction of high pelvic incidence (PI) and correction of sagittal imbalance.

METHODS

A 25-year-old female patient presented with a disabling lumbo-sacral kyphosis fused in situ through previous operations with residual low-grade wound infection and grade IV L5/S1 spondylolisthesis with severity index (SI) of 65%. A two-stage correction was performed. First anterior in situ fixation of the L4-L5-S1 segments was performed using a hollow modular anchorages (HMA) screw and L3/L4 anterior interbody cage. The second stage consisted of instrumentation of the lower lumbar spine and pelvis; placement of an S1 transverse K-wire as pivot point and bilateral longitudinal sacral osteotomy which allowed for gradual retroversion of the central sacrum relative to the pelvis.

RESULTS

Sacrum was derotated by 30° which allowed to restore spinal sagittal balance and decrease SI by 15%. Postoperative recovery was complicated by a flare up of the pre-existing deep wound infection.

CONCLUSIONS

Bilateral longitudinal sacral osteotomy appears to be a safe and efficient way of correcting the sagittal imbalance caused by an extremely high PI. Although technically demanding, it achieves good radiological and functional outcomes and avoids entering the spinal canal.

Implications of spinopelvic alignment for the spine surgeon

The relation of the pelvis to the spine has previously been overlooked as a contributor to sagittal balance. However, it is now recognized that spinopelvic alignment is important to maintain an energy-efficient posture in normal and disease states. The pelvis is characterized by an important anatomic landmark, the pelvic incidence (PI). The PI does not change after adolescence, and it directly influences pelvic alignment, including the parameters of pelvic tilt (PT) and sacral slope (SS) (PI = PT 1 SS), overall sagittal spinal balance, and lumbar lordosis. In the setting of an elevated PI, the spineadapts with increased lumbar lordosis. To prevent or limit sagittal imbalance, the spine may also compensate with increased PT or pelvic retroversion to attempt to maintain anupright posture. Abnormal spinopelvic parameters contribute to multiple spinal conditions including isthmic spondylolysis, degenerative spondylolisthesis, deformity, and impact outcome after spinal fusion. Sagittal balance, pelvic incidence, and all spinopelvic parameters are easily and reliably measured on standing, full-spine (lateral) radiographs, and it is essential to accurately assess and measure these sagittal values to understand their potential role in the disease process, and to promote spinopelvic balance at surgery. In this article, we provide a comprehensive review of the literature regarding the implications of abnormal spinopelvic parameters and discuss surgical strategies for correction of sagittal balance. Additionally, the authors rate and critique the quality of the literature cited in a systematic review approach to give the reader an estimate of the veracity of the conclusions reached from these reports.

Sacral and pelvic osteotomies for correction of spinal deformities

INTRODUCTION

Restoring a physiological sagittal spine balance is one of the main goals in spine surgery. Several technics have been described previously, as pedicle subtraction osteotomy. In more complicated cases involving spino-pelvic disorders, three authors proposed sacral osteotomy to restore sagittal balance of the spine. The authors describe the use of pelvic osteotomies for the correction of lumbo-sacral kyphosis, for decreasing pelvic incidence and for achieving sagittal balance correction in cases of lumbo-sacral sagittal deformity as an alternative of pedicle subtraction osteotomies (PSO).

MATERIALS AND METHODS

We simulate four types of pelvic osteotomies previously described for hip pathology (Salter, modified Salter, Chiari and posterior sacral osteotomy) on drawing software, and calculate during these osteotomies the variation of pelvic incidence (PI). Then, we compare the behaviour in this simulation to a cadaveric model where we perform the same four pelvic osteotomies. Via X-rays made the study, we calculate also the PI. Then, we analyse 11 patients who underwent pelvic osteotomies for sagittal unbalance, analysing operative and clinical data.

RESULTS

We find a mathematical law governing the PI during anterior opening and posterior closing osteotomies (respectively Salter and sacral osteotomy):[Formula: see text]These laws are confirmed in the cadaveric model which retrieves the same behaviour. In the clinical series, Salter osteotomy is easy and efficient on sagittal rebalancing; sacral osteotomy is more powerful.

DISCUSSION

The Salter osteotomy is efficient for restoring sagittal balance of the spine. The posterior sacral osteotomy is more powerful but technically demanding. The indications of such special osteotomies are fixed lumbo-sacral kyphosis, especially high-grade spondylolisthesis, previously operated or not.

CONCLUSION

A study of a more substantial series would be considered.

Implications of spinopelvic alignment for the spine surgeon

The relation of the pelvis to the spine has previously been overlooked as a contributor to sagittal balance. However, it is now recognized that spinopelvic alignment is important to maintain an energy-efficient posture in normal and disease states. The pelvis is characterized by an important anatomic landmark, the pelvic incidence (PI). The PI does not change after adolescence, and it directly influences pelvic alignment, including the parameters of pelvic tilt (PT) and sacral slope (SS) (PI = PT + SS), [corrected] overall sagittal spinal balance, and lumbar lordosis. In the setting of an elevated PI, the spineadapts with increased lumbar lordosis. To prevent or limit sagittal imbalance, the spine may also compensate with increased PT or pelvic retroversion to attempt to maintain anupright posture. Abnormal spinopelvic parameters contribute to multiple spinal conditions including isthmic spondylolysis, degenerative spondylolisthesis, deformity, and impact outcome after spinal fusion. Sagittal balance, pelvic incidence, and all spinopelvic parameters are easily and reliably measured on standing, full-spine (lateral) radiographs, and it is essential to accurately assess and measure these sagittal values to understand their potential role in the disease process, and to promote spinopelvic balance at surgery. In this article, we provide a comprehensive review of the literature regarding the implications of abnormal spinopelvic parameters and discuss surgical strategies for correction of sagittal balance. Additionally, the authors rate and critique the quality of the literature cited in a systematic review approach to give the reader an estimate of the veracity of the conclusions reached from these reports.

Should symptomatic iliac screws be electively removed in adult spinal deformity patients fused to the sacrum?

STUDY DESIGN

Retrospective, single-institution review of adult deformity patients who underwent iliac screw (IS) removal placed during fusion to the sacrum.

OBJECTIVE

To demonstrate whether IS removal offered benefit in terms of hip/buttock pain overlying the IS and whether IS could be removed without significant complications.

SUMMARY OF BACKGROUND DATA

ISs are effective at countering cantilever forces imparted on sacral pedicle screws. Despite the efficacy of IS fixation, pain or implant prominence can lead to elective IS removal. There has been no study about IS removal in adult spinal deformity patients.

METHODS

A total of 395 consecutive walking adult spinal deformity patients fused to the sacrum with IS fixation and minimum 2-year follow-up met study inclusion criteria. Clinical/radiographical data were analyzed. Because there is no validated pain outcomes instrument specific to this situation, an 8-question IS removal questionnaire was designed and used for the sole purpose of this inquiry, within which a universally accepted numeric rating scale for pain was included. RESULTS.: Twenty-four of 395 (6.1%) patients (2 men and 22 women) with mean age of 50.5 ± 10.8 years underwent elective IS removal at mean 2.6 ± 1.3 years from index surgery. Mean follow-up from initial surgery was 6.3 ± 4.0 years. Symptoms included hip/buttock pain in all 24 patients and IS prominence in 5 patients (20.8%). Screw removal was bilateral in 18 (75%) patients and unilateral in 6 (25%) patients. Using a numeric rating pain scale (0-10), hip/buttock pain improved after IS removal: preoperative 6.9 ± 1.8, postoperative 2.0 ± 2.7 (P < 0.05). Patients reported hip/buttock symptoms post-IS removal as "much improved" (78.3%), "somewhat improved" (8.7%), and "unchanged" (13.0%). Two of 24 (8.3%) patients sustained complications from IS removal (wound infection, n = 1; coronal/sagittal imbalance, n = 1). Presented with the same set of circumstances, 22 of 24 (91.7%) patients would have their IS removed again, including one of the patients who had a complication.

CONCLUSION

Of 395 consecutive walking patients who had ISs placed during fusion to the sacrum for adult spinal deformity, 24 (6.1%) underwent elective removal. Patients had a statistically significant improvement in hip/buttock pain after IS removal, and a low prevalence of complications after the procedure was observed.

Sacral tumor resection and the impact on pelvic incidence

Object

Pelvic incidence (PI) directly regulates lumbar lordosis and is a key determinant of sagittal spinal balance in normal and diseased states. Pelvic incidence is defined as the angle between the line perpendicular to the S-1 endplate at its midpoint and the line connecting this point to a line bisecting the center of the femoral heads. It reflects an anatomical value that increases with growth during childhood but remains constant in adulthood. It is not altered by changes in patient position or after traditional lumbosacral spinal surgery. There are only 2 reports of PI being altered in adults, both in cases of sacral fractures resulting in lumbopelvic dissociation and sacroiliac (SI) joint instability. En bloc sacral amputation and sacrectomy are surgical techniques used for resection of certain bony malignancies of the sacrum. High, mid, and low sacral amputations result in preservation of some or the entire SI joint. Total sacrectomy results in complete disruption of the SI joint. The purpose of this study was to determine if PI is altered as a result of total or subtotal sacral resection.

Methods

The authors reviewed a series of 42 consecutive patients treated at The Johns Hopkins Hospital between 2004 and 2009 for sacral tumors with en bloc resection. The authors evaluated immediate pre- and postoperative images for modified pelvic incidence (mPI) using the L-5 inferior endplate, as the patients undergoing a total sacrectomy are missing the S-1 endplate postoperatively. The authors compared the results of total versus subtotal sacrectomies.

Results

Twenty-two patients had appropriate images to measure pre- and postoperative mPI; 17 patients had high, mid, or low sacral amputations with sparing of some or the entire SI joint, and 5 patients underwent a total sacrectomy, with complete SI disarticulation. The mean change in mPI was statistically different (p < 0.001) for patients undergoing subtotal versus those undergoing total sacrectomy (1.6° ± 0.9° vs 13.6° ± 4.9° [± SD]). There was no difference between patients who underwent a high sacral amputation (partial SI resection, mean 1.6°) and mid or low sacral amputation (SI completely intact, mean 1.6°).

Conclusions

The PI is altered during total sacrectomy due to complete disarticulation of the SI joint and discontinuity of the spine and pelvis, but it is not changed if any of the joint is preserved. Changes in PI influence spinopelvic balance and may have postoperative clinical importance. Thus, the authors encourage attention to spinopelvic alignment during lumbopelvic reconstruction and fixation after tumor resection. Long-term studies are needed to evaluate the impact of the change in PI on sagittal balance, pain, and ambulation after total sacrectomy.

PEDICLE SUBTRACTION OSTEOTOMY

OBJECTIVE

Pedicle subtraction osteotomy (PSO) is an effective tool for the correction of fixed sagittal plane deformity. However, there is potentially significant perioperative morbidity associated with this technique. We report our perioperative morbidity rate in recently performed PSO cases treated with our present surgical, anesthetic, and monitoring techniques and discuss complication-avoidance strategies.

METHODS

We conducted a retrospective study of 10 patients (mean age, 56 yr; range, 7–77 yr) undergoing thoracolumbar PSO at a single institution in the past 3 years. Two patients underwent PSO at T12, seven patients underwent PSO at L3, and one patient underwent PSO at L2. Eight of the patients had undergone at least one previous spine surgery in the region of the PSO, and nine of the patients had comorbidities that increased their surgical risk stratification. We identified all causes of perioperative morbidity.

RESULTS

We classified perioperative complications into two categories: intraoperative and early postoperative. Intraoperative complications included dural tears in two patients, cardiovascular instability in one patient, and coagulopathy in two patients. Early postoperative complications included neurological deficit (one patient), wound infection (two patients), urinary tract infection (one patient), and delirium (two patients). All patients recovered fully from these complications. There was no mortality in this series.

CONCLUSION

In this series, most patients undergoing PSO had multiple previous spine surgeries and comorbidities. The risk of perioperative morbidity for revision cases undergoing PSO was in excess of 50%. We discuss complication-avoidance strategies.