Classifications in Brief: The Denis Classification of Sacral Fractures

Development of a sacral fracture model to demonstrate effects on sagittal alignment

PURPOSE

To develop a modeling framework to predict the secondary consequences on spinal alignment following correction and to demonstrate the impact of pedicle subtraction osteotomy (PSO) location on sagittal alignment.

METHODS

Six patients were included, and pelvic incidence (PI) was measured. Full-length standing radiographs were uploaded into PowerPoint and manipulated to model S1-S2 joint line sacral fractures at 15°, 20°, 25°, and 30°. PSO corrections with hinge points at the anterior superior corner and vertical midpoint of the L3-5 vertebral bodies were modeled. Anterior translation (AT) and vertical shortening (VS) were calculated for the six PSO locations in the four fracture angle (FA) models.

RESULTS

PI had a strong effect in the mixed AT and VS models (P < 0.001). Both AT and VS were significantly different from zero at all FA (p < 0.001), and pairwise comparisons revealed all FA were different from each other with respect to both AT and VS after adjusting for PSO location (p < 0.001), increasing as FA increased. Varying PSO location resulted in significant differences in AT when comparing all locations (p < 0.001). AT was greatest for all FA in all patients when the PSO correction was performed at the L3-AS (p < 0.001). There were significant differences in VS when comparing the L5-Mid PSO location to the L3-AS, L3-Mid, L4-AS, and L4-Mid PSO locations (p < 0.034).

CONCLUSION

PSO correction superior to a sacral fracture resulted in AT and VS of the spine. It is crucial that these changes in spinal measures be predicted and accounted for to optimize patient sagittal alignment and outcomes.

Spinopelvic Dissociation Case Report and Literature Review

A 32-year-old male was brought to our emergency department following trauma due to fall of heavy object (tree) on his back. After Advanced Trauma Life Support (ATLS) protocol implementation, the patient was noted to have a complete perianal tear and loss of power in L3-S1 measuring 1/5 complete loss of sensation below the level of L2. Imaging showed spinopelvic dissociation with cauda equina syndrome. Spinopelvic fixation and fusion with rigid fixation done. The patient regained normal function following extensive physiotherapy. This paper concludes that good and prompt surgical intervention facilitated neurological recovery following decompression.

Evolution of the AO Spine Sacral and Pelvic Classification System: a systematic review

OBJECTIVE

The purpose of this study was to describe the genesis of the AO Spine Sacral and Pelvic Classification System in the context of historical sacral and pelvic grading systems.

METHODS

A systematic search of MEDLINE, EMBASE, Google Scholar, and Cochrane databases was performed consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify all existing sacral and pelvic fracture classification systems.

RESULTS

A total of 49 articles were included in this review, comprising 23 pelvic classification systems and 17 sacral grading schemes. The AO Spine Sacral and Pelvic Classification System represents both the evolutionary product of these historical systems and a reinvention of classic concepts in 5 ways. First, the classification introduces fracture types in a graduated order of biomechanical stability while also taking into consideration the neurological status of patients. Second, the traditional belief that Denis central zone III fractures have the highest rate of neurological deficit is not supported because this subgroup often includes a broad spectrum of injuries ranging from a benign sagittally oriented undisplaced fracture to an unstable "U-type" fracture. Third, the 1990 Isler lumbosacral system is adopted in its original format to divide injuries based on their likelihood of affecting posterior pelvic or spinopelvic stability. Fourth, new discrete fracture subtypes are introduced and the importance of bilateral injuries is acknowledged. Last, this is the first integrated sacral and pelvic classification to date.

CONCLUSIONS

The AO Spine Sacral and Pelvic Classification is a universally applicable system that redefines and reorders historical fracture morphologies into a rational hierarchy. This is the first classification to simultaneously address the biomechanical stability of the posterior pelvic complex and spinopelvic stability, while also taking into consideration neurological status. Further high-quality controlled trials are required prior to the inclusion of this novel classification within a validated scoring system to guide the management of sacral and pelvic injuries.

Percutaneous sacroiliac screw fixation in a pediatric with unstable bilateral superior rami and sacral fracture-dislocation; a case report and review of the literature

Complex pelvic ring injuries in childhood can be difficult to treat, and literature mentions several techniques for fixing SIJ fracture-dislocations. In accordance with the CAse REport (CARE) guidelines, this study describes a five-year-old boy with a complex pelvic ring fracture caused by a car accident: vertically unstable pelvic fracture consists of bilateral superior rami fractures and type I of Denis sacral fracture. Fixation was achieved by inserting a 6.5 mm major diameter cannulated screw with a 60 mm length and 16 thread into the SIJ at the level of S1. The pelvic inlet view corrected the anterior-posterior position, and the pelvic outlet view adjusted the superior-inferior position to determine a suitable sacral level. After three months, the SI joint has shown an anatomically fracture consolidation, and he could ambulate with full weight-bearing and full ROM with no pain. A 3-year follow-up showed promising results in radiological and functional terms.

We conclude that percutaneous SI screw fixation using a cannulated screw is a suitable technique for pediatrics because it provides anatomic reductions and is minimally invasive. Children as young as five can be treated safely with SI screws for sacral fractures and SIJ injuries.

Lumbar instability as an etiology of low back pain and its treatment by prolotherapy: A review

BACKGROUND

Low back pain is a significant spinal disorder that affects much of the population at some point during their lives.

OBJECTIVE

While proper diagnosis is key, diagnosing the underlying cause of low back pain may often be unclear.

METHOD

In this review article, we discuss lumbar instability as an etiology of low back pain and its treatment by prolotherapy.

RESULTS

Spinal ligaments may be an underlying culprit in the development of lumbar instability with resultant low back pain and associated disorders.

CONCLUSION

In these cases, adequate treatment consisting of non-biologic prolotherapy or cellular prolotherapy, including platelet rich plasma (PRP), can be beneficial in restoring spinal stability and resolving chronic low back pain.

Functional, morphological and molecular characteristics in a novel rat model of spinal sacral nerve injury-surgical approach, pathological process and clinical relevance

Spinal sacral nerve injury represents one of the most serious conditions associated with many diseases such as sacral fracture, tethered cord syndrome and sacral canal tumor. Spinal sacral nerve injury could cause bladder denervation and detrusor underactivity. There is limited clinical experience resolving spinal sacral nerve injury associated detrusor underactivity patients, and thus the treatment options are also scarce. In this study, we established a spinal sacral nerve injury animal model for deeper understanding and further researching of this disease. Forty 8 w (week) old Sprague Dawley rats were included and equally divided into sham (n = 20) and crush group (n = 20). Bilateral spinal sacral nerves of rats were crushed in crush group, and sham group received same procedure without nerve crush. Comprehensive evaluations at three time points (1 w, 4 w and 6 w) were performed to comprehend the nature process of this disease. According to urodynamic test, ultrasonography and retrograde urography, we could demonstrate severe bladder dysfunction after spinal sacral nerve injury along the observation period compared with sham group. These functional changes were further reflected by histological examination (hematoxylin-eosin and Masson's trichrome staining) of microstructure of nerves and bladders. Immunostaining of nerve/bladder revealed schwann cell death, axon degeneration and collagen remodeling of bladder. Polymerase Chain Reaction results revealed vigorous nerve inflammation and bladder fibrosis 1 week after injury and inflammation/fibrosis returned to normal at 4 w. The CatWalk gait analysis was performed and there was no obvious difference between two groups. In conclusion, we established a reliable and reproducible model for spinal sacral nerve injury, this model provided an approach to evaluate the treatment strategies and to understand the pathological process of spinal sacral nerve injuries. It allowed us to understand how nerve degeneration and bladder fibrosis changed following spinal sacral nerve injury and how recovery could be facilitated by therapeutic options for further research.

Spinal nerve compression after malunion of vertical sacrum fractures

Introduction and importance

Unstable pelvic ring injuries often occur in high energy traumas. Vertical sacrum fracture is an associated injury. This report describes a late spinal nerve compression that occurred following surgical reduction and fixation of pelvic ring injuries caused by traumatic L5-S1 disc herniation and malposition of the sacral fracture.

Case presentation

A 61-year-old female presented with radiculopathy in her right leg after surgical reduction and fixation of a sacral and pelvic fracture. Physical examination revealed numbness and weakness of the right leg. Radiographic studies showed spinal compression caused by a fracture spike from the malunion of the sacrum and protruding disc from the L5/S1 level. The fracture spikes were removed by laminectomy and discectomy after which the patient's condition had improved and she had no recurrent symptoms at the one-year follow-up.

Clinical discussion

Malunion of a posterior pelvic ring fracture and a herniated adjacent intervertebral disc can cause sacral nerve root compression. This complication can be managed and satisfactory results achieved by surgical intervention.

Conclusion

Traumatic L5-S1 disc herniation and malposition following surgical reduction and fixation of a sacrum fracture can be avoided. Posterior decompression by laminectomy and discectomy is an effective alternative treatment for patients with this condition.

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Malunion of a vertical sacral fracture can present with radicular symptoms

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Traumatic L5-S1 disc herniation and malposition of sacral fracture can occur after reduction and fixation of a pelvic and sacral fracture, causing spinal compression.

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This condition can be managed by laminectomy and discectomy, which can provide satisfactory results.

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This modified technique can provide long-term relief of radicular symptoms.

Emergency Department Stress Radiographs of Lateral Compression Type-1 Pelvic Ring Injuries Are Safe, Effective, and Reliable

BACKGROUND

Occult instability of lateral compression type-1 (LC1) pelvic ring injuries may be determined with a fluoroscopic stress examination under anesthesia (EUA) performed in the operating room. We hypothesized that LC1 injuries, similar to some fractures of the extremities, could be radiographically stressed for stability in the emergency department (ED). Our primary objective was to determine if stress examination of LC1 fractures could be safely and accurately performed in the ED and could be tolerated by patients.

METHODS

A prospective, consecutive series of 70 patients with minimally displaced LC1 pelvic injuries (<10-mm displacement on presentation) underwent stress examinations performed by the on-call orthopaedic resident in the ED radiology suite. The stress examination series included static 40° inlet, internal rotation stress inlet, and external rotation stress inlet views. Pelvic fractures that had positive stress results (≥10 mm of overlap of the rami) were indicated for a surgical procedure. These fractures also underwent EUA in order for the 2 techniques to be compared.

RESULTS

All patients tolerated the ED stress examination without general anesthetic or hemodynamic instability. Fifty-seven patients (81%) had negative stress results and were allowed to bear weight. All patients with negative stress results who had 3-month follow-up went on to radiographic union without substantial displacement. For the patients with a positive stress result in the ED, the mean displacement was 15.15 mm (95% confidence interval [CI], 10.8 to 19.4 mm) for the ED stress test and 15.60 mm (95% CI, 11.7 to 19.4 mm) for the EUA (p = 0.86). Two patients with a negative ED stress test did not mobilize during their hospitalization and underwent EUA and conversion to a surgical procedure. Thus, a total of 11 patients underwent both stress testing in the ED and EUA; no patient had a positive result on one test but a negative result on the other.

CONCLUSIONS

ED stress examination of LC1 injuries is a safe and reliable method to determine pelvic ring stability. The displacement measured in the ED stress examination is similar to the displacement measured under general anesthesia. Furthermore, a negative ED stress examination predicts successful nonoperative treatment. Given the results of this study, we encourage the use of stress examination in the ED for LC1-type injuries involving complete sacral fractures only. Widescale adoption of this streamlined protocol may substantially diminish cost, anesthetic risk, and potential operations for patients.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical Effects of a Cross Connector in Sacral Fractures - A Finite Element Analysis

Background: Spinopelvic fractures and approaches of operative stabilization have been a source of controversial discussion. Biomechanical data support the benefit of a spinopelvic stabilization and minimally invasive procedures help to reduce the dissatisfying complication rate. The role of a cross connector within spinopelvic devices remains inconclusive. We aimed to analyze the effect of a cross connector in a finite element model (FE model). Study Design: A FE model of the L1-L5 spine segment with pelvis and a spinopelvic stabilization was reconstructed from patient-specific CT images. The biomechanical relevance of a cross connector in a Denis zone I (AO: 61-B2) sacrum fracture was assessed in the FE model by applying bending and twisting forces with and without a cross connector. Biomechanical outcomes from the numerical model were investigated also considering uncertainties in material properties and levels of osseointegration. Results: The designed FE model showed comparable values in range-of-motion (ROM) and stresses with reference to the literature. The superiority of the spinopelvic stabilization (L5/Os ilium) ± cross connector compared to a non-operative procedure was confirmed in all analyzed loading conditions by reduced ROM and principal stresses in the disk L5/S1, vertebral body L5 and the fracture area. By considering the combination of all loading cases, the presence of a cross connector reduced the maximum stresses in the fracture area of around 10%. This difference has been statistically validated (p < 0.0001). Conclusion: The implementation of a spinopelvic stabilization (L5/Os ilium) in sacrum fractures sustained the fracture and led to enhanced biomechanical properties compared to a non-reductive procedure. While the additional cross connector did not alter the resulting ROM in L4/L5 or L5/sacrum, the reduction of the maximum stresses in the fracture area was significant.