SACRAL FRACTURE TREATMENT WITH A VARIATION OF THE LUMBOPELVIC FIXATION

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


INTRODUCTION
Sacral fractures with spinopelvic instability are rare, and are the result of high-energy trauma with axial overload through the sacrum. 1,2][3][4] Another important aspect is the high rate of underdiagnosis of spinopelvic instability. 5The panoramic radiography of the pelvis, used in the routine evaluation of patients with multiple trauma, is insufficient to identify fractures of the sacrum with spinopelvic instability.The intestinal loops and sacral tilt can hinder the visualization of the transverse fracture. 6In addition, the pain originating from coexisting lesions can mask complaints coming from the sacropelvic region, contributing to underdiagnosis. 48][9] The conservative approach has been related to the worsening of the sacral deformity, aggravation of neurological symptoms, and higher mortality rates.][9][10][11][12][13][14][15][16] The rarity of sacral fractures, which may evolve with spinopelvic instability, makes standardization of techniques and evaluation of the postoperative results difficult. 9umbopelvic fixation (LPF) is currently a widely used method in the treatment of spinopelvic instability. 1,9,13The technique provides posterior stabilization of the pelvic ring, with stable realignment between the ilium, upper sacral fragment, and lumbar spine..17The lack of adequate implants for the sacral anatomy is a limitation of the LPF technique.Around 20% of patients were reoperated due to prominence of the screws or breakage of the synthesis material used in the stabilization. 1,18[21][22][23]

METHODS
Introducing a variation of the LPF used in the treatment of a multiplanar fracture of the sacrum with spinopelvic instability.The study was approved by the Institutional Review Board where it was conducted (CAAE: 51609815.1.0000.5273)and the patient agreed to participate voluntarily, by signing the informed consent form.

Case Description
A female patient, 21 years of age, admitted after a fall from 12 meters of height, with longitudinal trauma on the lower limbs.After initial clinical stabilization, physical examination revealed perianal hypoesthesia, absence of anal wink and bulbocavernosus reflex, and pain upon palpation of the lumbosacral bony prominences.The strength and deep reflexes of the lower limbs were normal.Radiological evaluation showed multiplanar fracture in the sacral 'H' indirectamente utilizando la extensión de la cadera y las maniobras de tracción femoral, asociadas con maniobras de distracción a través de vástagos.Pinzas de reducción fueron utilizadas para reducir la desviación cifótica del fragmento sacro inferior, lo que permite su fijación al sistema lumbopélvico de vástago y tornillos.No hubo complicaciones de infección, dehiscencia de la sutura o ruptura de implantes y al final del primer año de seguimiento, la cifosis sacral estaba normal y se confirmó la consolidación radiográfica.Nuestra técnica proporciona una alternativa viable y prometedora al FLP tradicional, por lo que es especialmente útil en las fracturas con desviaciones acentuadas del fragmento sacro inferior.Nivel de Evidencia: IV.Tipo de estudio: Serie de caso Descriptores: Sacro; Heridas e lesiones; Cifosis.
(variant of 'U' fracture), with longitudinal fractures extending beyond the lower sacral fragment.There was 60° kyphosis at the level of the transverse fracture, causing a narrowing of the spinal canal.Fractures of the pubic branch and transverse processes of L5 were also identified (Figure 1).

Operative technique
On a radiotransparent table, with the patient in ventral decubitus, a median longitudinal incision was made, followed by subperiosteal dissection of the paravertebral muscles to expose the posterior elements of L5 to the sacrum.Facet osteotomies were performed at the level of L5-S1, to allow the insertion of pedicle screws in L5 and S1.Iliac screws were also inserted bilaterally.The left lateral pedicle of S2 was instrumented using the Mirkovic technique. 24Screws were inserted in S3, with medial orientation.In this vertebra, the intersection between a vertical line through the sacral foramina and a transverse line between the dorsal foramen of S2 and S3 was used as the entry point for the screw (Figure 2).Laminectomias of S1 and S2 were performed, allowing good visualization of the dural sac and sacral roots, which were intact.An initial attempt was made to reduce the sacral kyphosis the through hip extension.Additional longitudinal distraction and cantilever manoevers were performed through rods fixed to the screws of L5, S1 and iliac screws to reduce the upper sacral fragment.The smallest fragment of the sacrum (below the transverse fracture) was realigned with the sacral fragment, using bone tweezers, enabling the screws of S2 and S3 to be connected to the rods (Figure 2).The cartilage of joints L5-S1 and the sacroiliac joints was removed, and autologous bone obtained from the sacrum was grafted between the transverse processes of L5 and the sacral wings, between facets L5-S1 and between the sacroiliac joints, aiming at arthrodesis between them.The musculature was approached by planes, ensuring good coverage of the implants.Suction drains were inserted into the subcutaneous tissue, and the skin was sutured  without tension.After sacropelvic stabilization, the patient was placed in the supine position and the pubic branch fixed with a percutaneous screw.The devices used in the osteosynthesis are listed in Table 1.

Postoperative care and Follow-up
On the third postoperative day, walking was started with partial support.A week after surgery, the patient was already walking with only one crutch, and was discharged to outpatient follow-up.On discharge, radiographic images were obtained to evaluate the fracture alignment, position of the implants and decompression of the spinal cord.During outpatient follow-up, pelvic and lumbosacral radiographs were taken at six-week intervals during the first six months, to evaluate the kyphotic angle at the level of the transverse fracture line.[27][28][29]

RESULTS
The surgical procedure lasted three hours, with estimated blood loss of 380 ml.The total length of hospital stay was 10 days, and there were no complications, such as infection or dehiscence of the suture.The local pain and perineal paresthesia improved gradually, and after discharge, opioid analgesics were no longer needed.A favorable prognosis was confirmed based on the positive results listed in Table 2.In the second outpatient follow-up consultation, the patient was already walking without crutches and was able to full weight while standing on one leg (Figure 3).There were no reports of lumbar or pelvic pain during walking or lying down.
Sexual function, competence sphincteric and perineal sensitivity were normal.The patient's only complaint was discomfort in the areas where the implants were prominent, especially when sitting down.The postoperative showed imaging study showed no loss of correction of kyphosis or pelvic instability; evidence of consolidation was identified on the twelfth postoperative day (Figure 3).The patient returned to regular activities three months after surgery, and even with prominence of the implants, did not undergo repeat surgery to remove them.

DISCUSSION
Roy-Camille was the first to describe sacral 'U' fracture as a multiplane lesion: a transverse fracture in the axial plane combined with bilateral longitudinal fractures in the sagittal plane. 30.31This system evaluates the relationship between the upper and lower sacral fragments, but does not address possible variations in the components of the multiplane fracture.
3][4][5][6][7][8][9]15 In LPF, it is possible to stabilize the lumbopelvic transition even without the instrumentation of the sacrum, which may be fragmented, without areas for anchoring the implants.In classical 'U' fracture, the realignment of the upper and lower sacral fragments is obtained indirectly through the reduction maneuvers by the rods, thanks to the existence of a bone connection   between the lower fragment and the pelvis (Figure 2).The rarity of the sacral fractures with spinopelvic instability, as well as their morphological diversity, makes it difficult to standardize techniques for correcting and stabilizing these lesions.
In this study, we present a morphological variation of a 'U' fracture, classified as Roy-Camille type 2. The transversal component of the lesion was located between S1 and S2, while the longitudinal components extended below sacroiliac joints, forming an 'H' pattern (Figures 1 and 2).There was no bone connection between the lower sacral bone fragment and the remaining portions of the sacrum, or pelvis, making it impossible to correct the kyphosis at the level of the transverse fracture using the original LPF technique alone.
The decision to reduce the kyphosis deformity in sacral fractures with spinopelvic instability is based on well-established principles of the spinopelvic balance.][34] In addition, reducing the deformity restores the diameter of the rachidian canal, the obliteration of which was attributed to neurological deficits and chronic pain in the medium and long terms.Another advantage of correcting sacral deformity is the restoration of the pelvic dimensions, especially its anteroposterior diameter..36To correct the sacral kyphosis of fractures in 'U', we combined the LPF technique with a sacro-sacral technique.After the insertion of screws in L5, S1, S2, S3 and iliac screws, reduction of the upper sacral fragment was performed using maneuvers of hip extension and femoral traction.Additional maneuvers of compression and distraction were also performed through the rods, using the screws in L5 and the iliac crest as points of support (Figure 2).These maneuvers were not sufficient to achieve complete reduction of the kyphosis.Therefore, it was essential to vary the technique presented.
Transition rods originally developed for use in the cervicothoracic transition were adapted for LPF, allowing the use of smaller-diameter screws (originally developed for the cervical spine) in the lower sacral fragment (Table 1), which was reduced with the aid of bone tweezers, to be subsequently fixed in the pre-molded rods through the screws in S2 and S3 (Figure 2).This adaptation allowed the direct reduction and stabilization of the kyphosis, connecting the lower sacral fragment to the LPF after reduction.
The need for decompression of the spinal canal is another controversial issue in the surgical treatment of sacral fractures in general. 1,12,37,38As a rule, we performed decompression in all unconscious patients or those with neurological deficits whenever there was impairment of the spinal canal or foraminal comminution.In the case presented here, performing adequate clinical evaluations was a particular challenge.Despite the complaint of perineal hypoesthesia in the first clinical evaluation, the patient's depressive mood and lack of cooperation hindered topographic characterization of the findings, and follow-up.Given that the imaging exams showed obliteration of the spinal canal, and that open surgery was to be performed, we opted for decompressive laminectomy of S1 and S2.
Another important aspect of the LPF technique is performing arthrodesis of the sacroiliac joints.The residual mobility in these joints has been related to breakage of the implants, residual pain, and the need for reoperation. 1,39,40Bearing in mind the unfavorable psychosocial profile of the patient for subsequent procedures, it was decided to perform the sacroiliac arthrodesis.The patient did not report any pain, limitations in movement of the hip and lumbar spine, or changes in gait during the follow-up, but we agree that other clinical and biomechanical studies are needed to clarify the importance of this stage in LPF.Protrusion of the implant is the most common problem related to LPF. 35,36 This was also observed in our patient.Even without continuity lesions or ulcers resulting from pressure on the prominent areas, the patient complained about the aesthetic appearance in all the postoperative visits.The development of implants more suitable for use in LPF may reduce this problem, prompting even more surgeons to use this technique.
A greater number of cases and longer follow-up times are needed to evaluate the complications related to LPF. 3,[8][9][10]19 The same reasoning should be applied to the variation of the technique presented in our case. Untl now, the standardization of a technique for the treatment of sacral fractures with spinopelvic instability has not been possible, whether due to the low incidence of these injuries, or to the great morphological heterogeneity of sacral involvement.
The variation of the LPF technique presented here proved to be a viable and promising alternative for the treatment of sacral fractures with spinopelvic instability, especially in cases where the sacral kyphosis cannot be treated by the classical LPF technique alone.

Figure 1 .
Figure 1.Radiological evaluation.A, B Panoramic radiographs and Outlet View -gaseous shadows of the intestines and the sacral tilt, hindering visualization of the fracture; C-F.Computed Tomography -better visualization of the fracture pattern.

Figure 2 .
Figure 2. Illustrations of the fracture pattern and technique performed.A. variant in 'H' seen in the presented case; B. sacral fracture in 'U', with emphasis on the bone bridge between the lower sacral fragment and the sacroiliac joint; C. entry point for the insertion of the screws in S3; D. maneuver of hip extension used in the reduction of the sacral fragment; E. compression maneuvers used to complement the reduction of upper sacral fragment; F. Compression maneuvers used to complement the reduction of the lower sacral fragment.

Table 2 .
Clinical and functional assessment scores.