Spondylopelvic Dissociation

Spinopelvic dissociation (SPD) is a severe injury characterized by a discontinuity between the spine and the bony pelvis consisting of a bilateral longitudinal sacral fracture, most of the times through sacral neuroforamen, and a horizontal fracture, usually through the S1 or S2 body. The introduction of the concept of triangular osteosynthesis has shown to be an advance in the stability of spinopelvic fixation (SPF). However, a controversy exists as to whether the spinal fixation should reach up to L4 and, if so, it should be combined with transiliac-transsacral screws (TTS).

The purpose of this study is to compare the biomechanical behavior in the laboratory of four different osteosynthesis constructs for SPD, including spinopelvic fixation of L5 versus L4 and L5; along with or without TTS in both cases.

By means of a formerly described method by the authors, an unstable standardized H-type sacral fracture in twenty synthetic replicas of a male pelvis articulated to the lumbar spine, L1 to sacrum, (Model: 1300, SawbonesTM; Pacific Research Laboratories, Vashon, WA, USA), instrumented with four different techniques, were mechanically tested. We made 4 different constructs in 5 specimen samples for each construct. Groups: Group 1. Instrumentation of the L5-Iliac bones with TTS. Group 2. Instrumentation of the L4-L5-Iliac bones with TTS. Group 3. Instrumentation of L5-Iliac bones without TTS. Group 4: Instrumentation of L4-L5-Iliac bones without TTS.

According to our results, it can be concluded that in SPD, better stability is obtained when proximal fixation is only up to L5, without including L4 (alternative hypothesis), the addition of transiliac-transsacral fixations is essential.

Traumatic spinopelvic dissociation is a rare injury pattern resulting in discontinuity between the spine and bony pelvis. This injury is associated with a known risk of neurologic compromise which can impact the clinical outcome of these patients. We sought to determine incidence and characteristics of neurologic injury, outcomes following treatment, and predictive factors for neurologic recovery.

We reviewed the clinical documentation and imaging of 270 patients with spinopelvic dissociation from three Level-1 trauma centers treated over a 20-year period. From this cohort, 137 patients fulfilled inclusion criteria with appropriate follow-up. Details surrounding patient presentation, incidence of neurologic injury, and outcome variables were collected for each injury. Neurologic injuries were categorized using the Gibbons criteria. Multivariate analysis was performed to assess for patient and injury factors predictive of neurologic injury and recovery.

The overall incidence of neurologic injury in spinopelvic dissociation injuries was 33% (45/137), with bowel and/or bladder dysfunction (n=16) being the most common presentation. Complete neurologic recovery was seen in 26 cases (58%) and two patients (4%) improved at least one Gibbon stage in clinical follow-up. The most common long-term neurologic sequela at final follow-up was radiculopathy (n=12, 9%). Increased kyphosis was found to be associated with neurologic injury (p=0.002), while location of transverse limb and Roy-Camille type were not predictive of neurologic injury (p=0.31 and p=0.07, respectively). There were no factors found to be predictive of neurologic recovery in this cohort.

Neurologic injury is commonly seen in patients with spinopelvic dissociation and complete neurologic recovery was seen in the majority of patients at final follow-up. When present, long term neurologic dysfunction is most commonly characterized by radiculopathy. While increasing kyphosis was shown to be associated with neurologic injury, no patient or injury factors were predictive of neurologic recovery.

Sacral fractures in young healthy patients are usually linked to high-energy trauma. They are often associated with multiple other injuries. Isolated sacral fractures are rare and can be easily missed in the absence of other surrounding pelvic or spinal injuries. In this article, we present a rare case of isolated U-shaped displaced sacral fracture despite the high-energy mechanism of injury being missed on initial presentation. This is a 17-year-old healthy female who presented to the emergency department after falling from five-meter height. She complained of lower back pain and inability to ambulate. Physical examination revealed significant sacral tenderness, bilateral lower limb weakness and hypoesthesia, anesthesia of the saddle area, weak anal tone and absent anal reflex. Initial radiographs showed no apparent fractures. Further imaging by pelvic computed tomography, however, revealed an isolated U-shaped displaced sacral fracture. The patient was treated by decompression and lumbopelvic fixation by triangular osteosynthesis and iliosacral screw. This fixation method restored stability of the spinopelvic junction and allowed for early mobilization. At her 18-month follow-up visit, she showed minimal disability score (10%) on the Oswestry Disability Index. In conclusion, sacral fractures are considered exceedingly rare to occur in isolation and in young healthy patients.

Spinopelvic lesions are the result of high-energy vertical trauma with axial skeletal overload where the spine impacts onto the sacrum, dissociating the lumbar spine from the pelvis. Therefore, lumbopelvic instrumentations are aimed to counteract these vertical forces, although various biomechanical aspects of the combinations of different constructs (with or without iliosacral screws) or the number of lumbar fixation levels (L5 or the combination of L5 with L4) are subject to controversy. The number of patients in each published series is too short, and the nature of the fixation is very different from one article to another, making comparison very difficult. In this paper the methodology for laboratory studies is discussed. The design of the test bench fixture, biomechanical testing protocol and data analysis are very important when inference to the clinical setting is desired.

Spinopelvic injuries result from high energy trauma with overloading through the sacrum. These lesions can accomplish either bone fractures, ligament injuries or, most commonly, both. They may be accompanied with other associated life threatening injuries and cause biomechanical instability with potential fracture non-union, mal-union and subsequent lifetime pain and disability. Surgical stabilization of spinopelvic injuries requires planning in order to apply the appropriate osteosynthesis principles (compression; neutralization; buttressing and tension band).

In general terms simple sacral fractures can be treated under compression by iliosacral screws. However, as more complex ones cannot be compressed, they need vertical support and neutralization of shearing forces (neutralization and buttressing principles). For that purpose, spinopelvic instrumentations appear to be the current appropriate technique of stabilization. In the herein paper the general principles of sacral fracture osteosynthesis are discussed, as well as its application to spinopelvic injuries. Controversies on positioning, surgical approach, per-operative traction, sacral laminectomy, type of biomechanical construct, length of fixation, screws length, mode of weight bearing, and osteosynthesis hardware removal are discussed.

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.

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

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.

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

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.