Lumbopelvic Fixation in Unstable Traumatic Spinopelvic Sacral Fractures: Clinical and Radiological Outcome

Background Data: Although most sacral fractures can be treated conservatively, several surgical options are available for highly unstable fractures. Surgery aims to provide sacral realignment, fixation, and maybe neural decompression with subsequent pain relief and early mobilization. Surgical options are variable depending on the type of fractures and surgeon’s experience. Spinopelvic fixation is one of the famous surgical procedures. Purpose: To evaluate the safety and efficacy of lumbopelvic fixation for the treatment of unstable traumatic spinopelvic sacral fractures. Study Design: Prospective cohort study. Patients and Methods: All patients with unstable spinopelvic sacral fractures excluding those with other types of sacral fractures were recruited for this study. All patients were submitted to lumbopelvic fixation. Patients were evaluated clinically and radiologically, including full lumbar and pelvis X-Ray and 3D MSCT scan at the preand postoperative period. Clinical parameters included a full neurological examination, VAS, ODI, and modified Rankin scale. Results: A total of 15 patients including 7 males and 8 females with mean age of 28±8.11 years were recruited for this study. All patients were suffering from unstable traumatic spinopelvic type C sacral fractures according to AO Spine sacral fractures classification system. Four patients suffered from type C0, 2 from C1, 4 from C2, and 5 from C3. Neural insults were reported in 13 patients. The mean followup period was 19.2±8.6 (range, 6–36) months. The mean preoperative VAS improved from 8.13±1.25 to 2.6±1.01 postoperatively, while the mean preoperative ODI improved from 88.53±2.24 to 16.8±3.16 postoperatively. According to the modified Rankin scale for functional recovery, 14 (93.3%) of the patients were categorized as excellent and good, while only one patient (6.6%) was categorized as fair outcome. Complete fractures’ healing was reported in all patients and none required any revision procedure. Deformity correction was incomplete in 40% without clinical effects on patients. Surgical site infection was reported in 3 patients and one of them necessitated debridement.


INTRODUCTION
The sacrum is the mechanical nucleus of the axial skeleton serving as the base for the spinal column. Despite its mechanical importance, its transitional location between the spine and the pelvis has resulted in its being relatively overlooked by spine surgeons. 1 The lumbosacral neurologic function is protected by the sacrum and it maintains the spinal column and pelvic alignment. Thus, injuries to the sacrum may result in deformity, chronic pain, and loss of lower extremity function, bladder, bowel, and sexual function. 2 The surgical management for sacral fractures is challenging. Although they are rare injuries, they usually present with a wide variety of injury and fracture patterns. Sacral fractures often occur with pelvic and lower extremity fractures with or without concomitant neurologic dysfunction. 2 Sacral fracture with lumbopelvic dissociation usually happens after high-energy trauma. The most common mechanism is a jump or falls from height. 3 Due to the great variation in patterns of sacral fractures and associated fractures as well as neurological injuries, many classification systems have been proposed starting with Denis system, 4 Roy-Camille system, 5 and finally the AO Spine sacral fractures classification system introduced by the AO Spine. 6 The surgical options for treatment of sacral fractures are also variables and range from the percutaneous techniques to the open spinopelvic fixation procedure. Unstable sacral fractures are considered to be extremely devastating health problem that carry a great socioeconomic burden to either the patients, society, or health care providers. Spinopelvic fixation is one of the most important surgical options in the surgical management of these health problems.
This study aims to assess the safety and efficacy of the lumbopelvic fixation in the surgical management of unstable traumatic sacral fractures.

PATIENTS AND METHODS
Fifteen patients were prospectively recruited for this cohort study. All patients underwent the operation at Neurosurgery Department, Suez Canal University Hospital, through the period from 2016 to 2019 using the lumbopelvic fixation technique. All patients with unstable spinopelvic sacral fractures according to the AO Spine sacral fractures classification system excluding other types of sacral fractures were recruited for this study. Patients with other types of sacral fractures, metabolic bone diseases, and coagulopathy were excluded from our study. After stabilization of the general conditions of the patients, all patients were submitted to general and neurological evaluation. Clinical parameters included a full neurological examination, Visual Analog Scale (VAS) of back pain, and the Oswestry Disability Index (ODI). VAS was determined on a graphic chart between 0 (no pain) and 10 (maximum pain intensity). Neurological recovery and function were assessed using the Gibbons classification 7 of cauda equina impairment with its 4 subtypes: Type 1: none; Type 2: paresthesia only; Type 3: lower limb motor deficit; Type 4: bowel/bladder dysfunction. Patients were submitted to radiographic evaluations including; full lumbosacral and pelvis plain radiographs anteroposterior and lateral views and MS 3D CT-scan of the lumbosacral spine and pelvis. Types of fractures were categorized according to AO Spine sacral fractures classifications system. Immediately postoperative patients were submitted to full plain radiographs and MS 3D TC-scan of the lumbar spine and pelvis. This was repeated The EGYPTIAN SPINE Journal at 6 months intervals after surgery to assess the integrity of the spinopelvic construct and to assess the healing of fracture lines. Surgical Technique All the patients underwent operation under general anesthesia in the prone position under elective conditions after stabilization of the patient's general condition. Intraoperative fluoroscopy guidance was used throughout the whole procedure. All our patients were systematically submitted for the Galveston technique which was established by Allen and Ferguson. 8 Through a posterior midline approach, a subperiosteal muscle dissection was continued to expose L5 lamina and bilateral L5 screw entries. L5 screws were applied under image guidance before iliac screws were applied. We continued with subperiosteal dissection to expose the posterior superior iliac spine (PSIS). Once the PSIS was identified, we used a Leksell rongeur to make a small recess approximately 1.5 cm cephalad and medial to it to accommodate the head of the iliac screw. This was done to avoid subcutaneous prominence of the screw head from the ilium. Using the free-hand technique, iliac screws' purchase on the ilium was established. Two gear-shift pedicle probes were angled so that their shafts were parallel to the L5 lamina with the tip of the probe pointing to the notch created in the ilium. The shafts of the two probes should intersect each other over the L5 spinous process to confirm that they were still parallel to the lamina. The direction of each probe after these steps were completed was the trajectory that each iliac screw should take during placement. This is approximately the trajectory from the PSIS to the anterior inferior iliac spine. Screw length is identified based on preoperative imaging and intraoperative probing. The screw penetrates above the dense cortical bone which surrounds the superior aspect sciatic notch. Additionally, if they follow the optimum direction, the trajectory of the probe will parallel the L5-S1 facet joint. Each iliac screw was applied so that there was no substantial screw head prominence. Contoured rods were tapped directly on all screws; or, instead, connectors were used to connect the iliac screw to the contoured rods. Meticulous wound hemostasis and wound irrigation with betadine solution were performed, and a closed drain system was inserted. [9][10][11] Perioperative thirdgeneration cephalosporins were used for 5 days. Patients were discharged from the hospital when the drain was removed and the wound was in good condition. Postoperatively, patients were scheduled for routine outpatients' visits after 6 weeks, then at 3-month intervals where both back pain VAS and Oswestry Disability Index (ODI) were assessed at each visit. Full plain radiographs were performed at each visit and, in case of any further queries regarding healing, further 3D MSCT scan was requested. The endpoint of fracture union was defined by the disappearance of any visible fracture line in the sacral cortices on radiographs. Statistical Analysis Statistical analysis will be conducted using Statistical Package for Social Sciences (SPSS) version 20.0. The Kolmogorov-Smirnov, Shapiro, and D'Agostino tests were utilized to verify the normality of distribution of variables; the Mann-Whitney test was employed to compare the two groups for abnormally distributed quantitative variables. Pearson's coefficient was used to correlate between two normally distributed quantitative variables. Significance of the obtained results was judged at the 5% level. All data are expressed as mean±SD.

RESULTS
A total of 15 patients were prospectively recruited for this study. Seven (47%) patients were males and 8 (53%) were females with mean age 28±8.11 (range, 18-45) years. The reported causes of trauma were falling from heights in 10 (67%) including 5 suicidal attempts and road traffic accidents in 5 (33%) patients. (Table 1) According to AO Spine sacral fractures classification system, all reported patients were type C fractures distributed as follows: C0, 4 cases; C1, 2 cases; The EGYPTIAN SPINE Journal C2, 4 cases; C3, 5 cases. The reported associated injuries were diverse and included 2 spinal injuries including a traumatic L5/S1 spondylolisthesis and LV2 burst vertebral fracture. Other associated injuries included 5 patients with retroperitoneal hematoma, 6 with genitourinary injuries, and 4 with lower limb orthopedic fractures including 4 calcaneal and one femur fractures. Neurological assessment of patients showed that 2 patients were neurologically intact, and 9 (60%) patients suffered from urine retention, 4 from weak dorsiflexion, 5 from weak plantarflexion, 11 from saddle area anesthesia/hypesthesia, and 13 from lower limb sensory loss. (Table 2) All patients underwent lumbopelvic fixation using iliac screws in 10 patients (Figure 1,2) and S2 alar iliac screws in 5 patients. The lumbar anchoring points were L5 transpedicular screws in all cases. S1 pedicle screws were used in all 5 cases which were managed by S2 alar iliac screw as a distal anchoring point and in one case of associated traumatic pars fracture of L5-S1. One case of associated LV2 fracture was managed using transpedicular short segment screws fixation of LV1-LV3. (Figure 3) ( Table 1) There was no reported postoperative neurological deterioration in any of our patients. The mean operative time was 147.3±30.6 (range, 120-200) minutes, the mean operative blood loss 643±197 (range, 500-1000) ml, the mean hospital stays 12.8±3.8 (range, 7-19) days, and the mean follow-up period 19.2±8.6 (range, 6-36) months. The mean preoperative VAS improved from 8.13±12.5 (range, 6-10) to 2.6±10.1 (range, 1-5) postoperatively. The mean preoperative ODI improved from 88.53±8.2 (range, 86-92) to 16.8±7.6 (range, 12-22) postoperatively. According to the Gibbons classification of cauda equina impairment, the mean preoperative impairment type was 3.4±1.01 (range, 1-4). After a 6-month follow-up, the mean impairment type improved to 2.2±0.90 (rang, 1-4), while, after a 12-month followup, 13 out of 15 patients showed mean impairment improvement to 1.6±1.2 (range, 1-4). Ten patients out of 15 underwent surgical decompression during the procedures. The preoperative mean impairment of the decompression group improved from 4±0 (all patients underwent decompression were of type 4) to 2.5±0.80 and 2.1±1.1 at 6-and 12-month follow-up, respectively. In the other 5 patients, the mean impairment improved from 2.2±0.90 to 1.6±0.8 and 0.6±0.48 at 6 and 12 months, respectively. (Table 3) The correlation between the neurological outcome and the timing of surgery was not statistically significant at 6-month (r =0.397, p= 0.143) and at 12-month follow-up (r=0.497, p= 0.059). Moreover, the correlation between the neurological outcome and surgical decompression was statistically insignificant at 6-month and at 12-month followup (p-value was 0.129 and 0.679, respectively). Reported complications included the following: superficial surgical site infection in 3 (20 %), 2 of them treated with antibiotics and frequent dressings, while the other one treated with wound debridement followed by insertion of vacuum drain for 14 days. One patient underwent revision surgery for loosened cross-link, while the patient was still in the hospital. In this patient, we could not reduce the traumatic sacral kyphosis, and, meanwhile, he did not suffer from sphincter affection or significant back pain postoperatively. DVT was reported in one patient and managed well with anticoagulation therapy.
instability and neurologic impairment. Pelvic ring interruption, nerve root compression, cauda equina syndrome, and, on some occasions, associated direct injury to the spinal column were also reported as associated injuries with sacral fractures. 12 Although most sacral fractures can be treated conservatively, several surgical options are available for the management of unstable sacral fractures. The main clinical aims of surgery are to allow early mobilization of the patients and pain relief. This could be achieved through surgical stabilization and/or neural decompressive procedures. Surgical treatment is often offered to patients with unstable sacral fracture patterns, concomitant pelvic ring injury, and/or neurologic dysfunction with radiographic evidence of compression. 1 Patients with a stable pelvis doing well clinically could be managed conservatively. Other surgical indications include nerve root compression, fractures with pseudoarthrosis, and extensive lumbosacral disruption. 7 Relative indications for operations include multiple trauma cases to achieve early ambulation in order to aid in the process of rehabilitation. Besides obtaining fixation of the fracture, other aims include securing the lumbosacral equilibrium, promoting the clinical condition, and decreasing disability. Moreover, fixation of the sacral fractures provides stability which facilitates ambulation, preserves the sacral nerves and vessels, and relieves pelvic pain. 13,14 Unstable sacral fractures are usually associated with neural compromise. In this case, internal fixation is usually required to recover the pelvic strength and preserve the neural structure. 15 Adequate reduction and internal fixation for an unstable sacral fracture might avoid neural compromise due to fibrosis. 16 Cases with sacral fracture and neural compromise should undergo ner ve exploration and decompression to remove the fracture fragments from nerve roots. Clinical and neurologic improvement are elevated to 80% postoperatively. 17 This study reported 15 patients with unstable spinopelvic sacral fractures who underwent operation using the lumbopelvic fixation procedure. Acceptable reduction has been achieved in most patients and fractures showed osteal healing within 3 to 6 months postoperatively with no postoperative displacement. Before the 1960s, in situ fixation and prolonged bed rest with gypsum were the method of choice to achieve lumbosacral spine stability; 10 however, these were correlated with a high rate of nonunion (up to 50%). With the advancement of surgical modalities such as the Harrington-Luque and Cotrel-Dubousset techniques in spine surgery, the spine fusion ratio increased. However, disadvantages were detected such as back deformity, neural structure damage, and implant failure. With the recent improvement of internal fixation technology, more implants were adopted to accomplish lumbosacral spine stability in sacral fractures, such as lumboiliac plates, 5 transiliac plates, 18 transiliac rods, 19 and percutaneous iliosacral screws. 20 No agreement has been reached on the best technique for sacral fixation. The lumbopelvic internal fixation is one of the techniques that can accomplish lumbosacral fixation and spinal fusion and considerably increase the fusion ratio. 21 Reported complications of lumbopelvic fixation are mainly surgical site infection and implant failure with overall surgical site infection rate 26-50%. 22 Due to the delicate soft tissue in the sacrococcygeal region, the potentials of neural structure compromise the sacral fracture, sacral decompression technique might damage the blood supply of the nearby soft tissue, and the possibility of posteriorly protruding screw head, rod end, or red connectors is a major concern of the lumbopelvic fixation. 23 In a series with unstable first-and second-region fractures including 60 cases, Routt et al. 24 found that delays in the operation of 5 days or more were associated with weaker closed reduction ratios. Denis et al. 4 found that delays of more than 14 days had poorer results in cases doing well clinically. In our study, regarding the time of surgery after trauma, the cases that underwent the operation in the first 7 days had a higher rate of infection, while the cases that underwent operation later on had a much lower infection rate. This was attributed mainly to the presence of soft-tissue edema and stabilization of the general condition so they had better healing power. The Morel-Lavallée lesion is a soft-tissue injury reported with pelvic trauma in which the subcutaneous tissue is peeled away from the underlying fascia, resulting in a cavity filled with hematoma and seroma. A shearing force, for example, motor car accidents, has been incriminated to be the main cause. A study of 24 patients by Hak et al. 25 in 1997 reported that the commonest sites to be affected are lumbosacral and flank areas. Vanhegan et al. 26 after studying 204 lesions from 29 series revealed the frequency of the lumbosacral area to be 3.4%. These softtissue injuries varied in severity among patients and, whatever the severity, presence of hematoma and soft-tissue edema increase the risk of infection. 26 Moreover, the expanding hematoma in a closed internal degloving injury may further compromise the skin vascularity. In our series, we did not experience the classic degloving injury; however, in early cases, we experienced soft-tissue edema and muscular hematomas at the site of operation. In addition to this, the excessive use of electrocautery devitalizes the tissue more. As a result, antiedematous medications administration until the healing power of tissue improved, significantly reduce the postoperative infection rate. Regarding neurological outcome after neural decompression in this series, patients suffering from sphincter and/or neurological injuries showed no difference in outcome whether the operation was done early or late after trauma. Therefore, we recommend decompression as a part of correcting the deformity rather than enhancing neurologic recovery. The management of neurological injuries associated with sacral fractures is still problematic. Some advocates 27 support decompression routinely, while others 28 do not recommend routine surgical decompression as they think that neurological injury is a direct injury including contusions and lacerations. However, the comparative studies in the literature regarding functional and neurological recovery following sacral fractures are scarce. 29 Denis et al. 4 observed that five patients who had neurological improvement after surgical decompression with another case had conducted delayed surgical decompression and showed poor outcomes. Therefore, they supported early surgical decompression. Schmidek et al. 27 supported the same results in their 11-patient series with transverse sacral fractures after surgical decompression. Kim et al. 17 reported a group of 6 patients in which 5 patients neurologically improved. On the other hand, Sabastian and Wing 28 advised nonsurgical treatment for a group of 35 sacral fractures treated nonoperatively. This study, however, showed only one patient with a complete cauda equine syndrome who did not show significant neurological improvement. Phelan et al. 30 also recommend conservative treatment for these types of injuries. They followed up with only four patients who showed neurological recovery spontaneously. Nork et al. 20 reported neurological improvement in 7 patients who underwent percutaneous iliosacral fixation without surgical decompression and emphasized the importance of surgical fixation for neurological recovery. Elhabashy et al. 31 reported similar results in their study upon 20 patients operated for sacral fracture without surgical decompression using the percutaneous iliosacral screws. Some surgeons prefer to insert pedicle screws at L4 or L5 and S1 during iliolumbar fixation. As the plane of the sacrum screw is higher than that of the pedicle screw in this case, the fixed link must be bent into an S-shape so that it can fit adequately with the screws. 16 In our study, we used mainly L5 pedicle screws, iliac screws, and S2 alar iliac screws for fixation. By using the S2 alar iliac screws, we avoid excessive dissection too laterally to reach the posterior superior iliac spine. Tian et al. 32 recommended the use of long iliac screws with a trajectory toward the anterior inferior iliac spine just above the sciatic notch. This method created a center of rotation just anterior to the lumbosacral junction, protecting against the long lever arm force of flexion created by the The EGYPTIAN SPINE Journal spine component. 21 There are other techniques adopted to cross the sacral fractures that we did not use in this study and include iliosacral screws 31 and transsacral plating. 33 To overcome this issue, we used one transversal cross-link to convert the bilateral lumbopelvic fixation into a more rigid structure. These cross-links, despite being not strong enough in mechanics compared to other cross fixation techniques, facilitate the procedure and reduce its morbidity. Furthermore, they restabilize the disrupted posterior pelvic ring in continuity through compression. The number of anchor points needed in the lumbar and iliac area is still controversial. 34 Some authors 29 recommend a pair of pedicle screws in the L5 vertebra, providing adequate anchor points as long as there are no anterior pelvic ring injuries. On the other hand, the presence of anterior pelvic fractures and/or comminuted transverse fractures warrants the insertion of more screws. Furthermore, the current fusion procedures of sacral fractures are not motion preservation techniques that need further research studies in this field. 29 In our series, 3 patients developed surgical site infection which was mainly in the early cases and this was avoided in the later cases by reducing the usage of electrocautery (monopolar); instead, we used sharp technique in dissection using a scalpel, scissors, and bipolar for hemostasis. This decreased tissue necrosis and decreased exudates formation as a result of tissue degradation which resulted in a lower rate of postoperative infection or seroma formation. This observation was in agreement with Hak et al. 25 who reported that hematomas and soft-tissue edema in the operative site affect the safety of early operative intervention by increasing the risk of infection. The relationship between electrocautery and wound infection in different surgical specialties has been extensively studied, although it is scarce in neurosurgery practice. Sheikh et al. 35 performed 177 skin incisions for neurosurgical procedures using the microneedle electrocautery scalpel and the steel scalpel and reported only two cases of wound infection and dehiscence in the electrocautery group. In terms of the electrocautery usage in breast surgery which is a fatty area that could be associated with seroma formation and infection, Kathaleen et al. 36 reported seromas in 16 wounds in the electrocautery patients compared to only 5 in the scalpel arm (38% and 13%, respectively; P<0.01). Other results were reported in other studies 37,38 observing that electrocautery did not significantly affect the rate of postoperative subcutaneous wound infection. As a routine, all our patients received regular anti-deep venous thrombosis (DVT) measures; however, one of our patients developed postoperative DVT and has been managed with short-and long-term anticoagulants. There is an agreement that all trauma patients are at an increased risk of DVT. This consensus reported that patients with an acute head or spinal cord injury have a 40% incidence of DVT and a greater than 1% incidence of fatal pulmonary embolism (PE). 39 This study is limited by a low number of patients and the short-term follow-up period for that reason the validity of correlation and multivariate analysis and statistical significance cannot be relied on. A multicenter prospective study with long-term follow-up is recommended.