Abstract
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In young patients, lumbosacral fractures result primarily from high-energy traumas. Life-threatening lesions (e.g. visceral organs) are frequently associated with these fractures. Management consists of medical intensive care for adequate resuscitation and specialized surgical input.
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Lumbosacral junction represents a frontier between the spine and pelvic ring. Any injury in this area implies a thorough examination of both spine and pelvis through clinical examinations and CT scans. Patients must be assessed specifically for neurological and bladder/bowel symptoms. Several surgical classifications may be required to describe the entire fracture pattern.
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In unstable fracture with large displacements, definitive surgical fixation is often recommended. Various pelvic and spine surgery techniques can be used depending on the fracture pattern, surgeon’s experience, and available equipment. The use of intraoperative navigation may enhance placement of instrumentation, especially in cases of complex fractures, percutaneous fixations, and/or atypical patients’ anatomy.
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The fracture itself can cause debilitating complications with long-term consequences such as pain, neurological deficits, and bladder/bowel impairments. Wound infection remains the most common postoperative complication and prominent posterior instrumentation is frequently a source of pain. Irrespective of the treatment, leg discrepancy can be problematic in the case of malunion.
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Management of lumbosacral fractures requires a thorough understanding of both lumbar spine and pelvic injuries. Surgical treatment may involve a combination of spine and pelvic surgery techniques. Therefore, this implies for the surgeon to be trained specifically for these fractures, or else a close cooperation between the pelvic surgeon and the spine surgeon in managing the patients.
Introduction
Lumbosacral and sacral fractures are rare features that occur mostly after high-energy trauma in young patients (1, 2). In the context of this trauma, they are frequently associated with visceral lesions (brain, chest, abdomen) that are potentially life-treating. Due to the intimate relationship of the lumbosacral osseous components with the neural structures and the critical role played by the pelvis in transmitting forces between the spine and lower limbs, injuries in this area may also lead to substantial functional sequelae (2). In order to classify them and adapt surgical treatment, both clinical and radiological evaluations of lesions located at the lumbosacral junction are required. Since the sacrum, also called the pelvic vertebrae, is at the junction of the spine and the pelvis, it imparts forces between the inferior limbs and the spine via the pelvic ring (3). Furthermore, lumbosacral junction is a frontier between the spine and the pelvic ring in terms of anatomy, biomechanics, and trauma mechanisms, likewise between the spine surgeon and the pelvic surgeon. Knowing that, a major dilemma exists around these fractures. While pelvic surgeons are more amenable to manage these fractures than spine surgeons, surgical treatment of the most unstable fractures requires commonly lumbosacral fixation techniques that are more frequently used by spine surgeons.
What initial assessment should be done?
Clinical assessment
In the context of high-energy trauma, patients are often relatively young and polytraumatized. They require resuscitation while being investigated for life-threatening lesions. After the hemodynamic stabilization of the patient, one must assess the neurological function of an alert patient. Evaluation of the nerve roots from L4 to S4 is mandatory. The L5 nerve root is at risk in the L5/S1 foramina, and more importantly, the lumbosacral trunk is at high risk considering that it runs across the anterior aspect of sacral ala. Lumbosacral and sacral fractures are part of pelvic traumas; therefore, specific complications of pelvic traumas must be sought for (urinary, bowel, and skin lesions). Examination of the sacral nerve roots implies an assessment of urinary and bowel sphincters. Lesions of the sacral plexus lead to dramatic sequellae in these young trauma patients, leaving them potentially with urinary, bowel, and sexual impairments. Associated lesions in the case of sacral fractures are estimated as follows: 50% have pelvic ring fracture (pelvis or acetabulum), 30% have at least one spinal or lower limb fracture, almost 16% have abdominal trauma, and almost 11% cranial trauma (4).
Posterior skin and Morel-Lavallée lesions should be assessed and addressed accordingly.
Radiological assessment
Standard pelvic AP views are obtained in the trauma resuscitation bay to look for signs of pelvic disruption or elevation of the hemi-pelvis. However, lesions in this area can be easily overlooked on standard radiographs; therefore, CT scan is mandatory. One should look for L5 transverse process fracture, also named ‘sentinel fracture’, which may be indicative of a lumbosacral lesion (5). After hemodynamic stabilization is achieved, a whole-body CT scan including brain and thoracoabdominal CT with contrast is required for every polytrauma patient. CT scan at spine and pelvic levels may reveal lumbar and sacral compromise such as fractures and/or dislocations and is useful to analyze the various fractures’ displacements.
MRI might be indicated in case of traumatic lumbosacral dislocation which is a very rare injury. It serves to assess the L5/S1 disc looking for different disc lesions notably a compressive extruded disc that may cause neurological symptoms (radiculalgia, deficits).
Pelvic angiography is indicated in patients with suspicion of intrabdominal bleeding especially if they are hemodynamically unstable. Pelvic angioembolization is an effective treatment for bleeding pelvic injuries (6).
Anatomical and biomechanical considerations
Anatomy
Lumbosacral junction is a relatively ‘stiff’ region due to the presence of the L5/S1 disc, the articular processes of L5 and S1, and the iliolumbar ligaments attached from L4 and L5 transverse processes to the iliac crest.
The sacral bone is one piece of bone perforated by four foraminae for the sacral exiting nerve roots which represent a weakness in the bone where the fracture occurs more frequently. In elderly people, osteoporosis leads to a high frequency of fractures which are different from high-energy trauma and will not be developed in this article.
The sacrum, which has a triangular shape, is like a wedge inside the iliac crest via the sacroiliac joint (SIJ). The sacrum is attached to the pelvis by articular capsules and strong ligaments. The SIJ has a strong capsule and ligaments extended anteriorly from the sacrum to the ilium and posteriorly from the sacrum to the iliac crest. The sacrospinous ligament is attached from the ischiatic process to the lateral border of the sacrum and the sacrotuberal ligaments from the lateral border of the sacrum to the ischiatic tuberosity. These strong ligaments lock the pelvic ring.
Biomechanics
The lumbosacral junction represents a strong fixation with a tight connection between the spine, pelvis, and sacrum. Only high-energy traumas such as falls from height and car or motorcycle accidents can alter this junction. Consequently, sacral fractures following from high-energy trauma are part of a pelvic injury and should be analyzed accordingly.
The SIJs transmit forces between the spine and the lower limb via the ilium. Impairment of the SIJ will alter the gait. In addition, pain in the lumbar and pelvic areas will last a long time after injury because the lumbosacral area and the sacrum are highly innervated and connected to the pelvic floor.
Which classification is useful in practice?
Specific classification of the lumbosacral region does not exist. Because this is a junctional area, different classifications are involved, namely classifications of lumbosacral dislocations, pelvic fractures, and sacral fractures. In fact, what is crucial is to recognize lesions responsible for a total interruption of the continuity of the spine and the pelvis on one side or bilaterally (lumbopelvic dissociation).
Classification of lumbosacral dislocation
This entity was first described by Watson-Jones in 1938 (7). This rare entity accounts for only 1% of all spinal traumas (8, 9). We have proposed previously a classification: Type I represents a pure dislocation of the articular facets without fracture and can be divided into three subtypes: IA: unilateral rotary dislocation secondary to rotational traumatic forces; IB: bilateral facet joint dislocation with lateral displacement. The mechanism of injury seems to be hyperflexion associated with a lateral translational force; IC: bilateral dislocation, the mechanism involves flexion and distraction. In case IA and IB, there is no anterior slippage of L5 over the sacrum and the L5/S1 disc can be intact. Conversely, in type IC, there is an anterior slippage of L5 over S1 with a disruption of the L5/S1 disc which is the more frequent (8, 10). The risk of neurological symptoms is correlated to the amount of slippage with a high frequency of cauda equina deficit in anterior slippage greater than 30% (11). Type II represents unilateral articular process fracture dislocation and dislocation of the other facet. Type III represents bilateral fracture dislocation with anterior displacement and disc injury (Fig. 1).
Proposed lumbosacral dislocations classification (8).
Citation: EFORT Open Reviews 8, 5; 10.1530/EOR-23-0059
If the fracture goes through the pars interarticularis, it is a ‘traumatic’ isthmic spondylolisthesis as described in the Wiltse—Newman—Macnab classification (10).
Pelvis trauma classification
Traumas of the pelvis have been described by Tile (12, 13, 14) and modified by the AO trauma (15). There are three main types: type A = partial fracture with no instability including transverse fracture of the sacrum below S2; type B = fracture with horizontal instability; type C = fracture with vertical instability. In type B, the vertical opening of the posterior lesion can occur at the level of the sacrum or the SIJ. Type C is a lesion involving both the spine and the pelvis. Type C1 is a unilateral spinal dissociation, type C2 is a C1 lesion with a contralateral B lesion, and C3 is a bilateral vertical lesion representing the lumbopelvic dissociation (Fig. 2).
Tile classification of pelvic fractures (type A, B, and C lesions). Types B and C fracture lines are here represented through the sacrum.
Citation: EFORT Open Reviews 8, 5; 10.1530/EOR-23-0059
Sacral fractures
Sacral fractures were initially described by Denis (16) and further refined by Roy-Camille (5) and by the AO classification. Denis described three vertical fracture lines. zone I = through the sacral area (50% of cases with 5.9% of neurological lesion of the lumbosacral trunk); zone II = through the sacral foramen (34% of cases with 28.4% of sacral plexus lesions); zone III through the sacral canal (16% of cases with 56% of neurological lesion with partial or total cauda equina syndrome). Further studies have shown that the rate of neurological impairment was lower with 1.9% in zone I, 5.8% in zone II, and 8.6% in zone III (17). Gibbons defined the neurological impairment linked to sacral fracture (18).
In 1985, Roy-Camille first described a fracture called ‘suicidal jumper’s fractures’, which is a transverse fracture of the sacrum (between S1 and S2) with a longitudinal transforaminal bilateral sacral fracture causing dissociation of the spine and the upper body of the sacrum from the pelvis and the sacral wings (5). This spinopelvic dissociation (SPD) was divided into three main groups, based on the level of displacement on the sagittal plane (Fig. 3). The distal sacral fragment (connected to the pelvis) either rotates in extension or flexion relative to the upper sacral fragment (connected to spine) because of the injury mechanism and this rotation creates lumbosacral kyphosis or lordosis. If the spine is in flexion during the trauma the displacement will be in kyphosis resulting in type 1 (with posterior cortex intact) or type 2. Conversely, an extension of the spine will lead to type 3. The SPD can change the shape of the sacrum and acetabulum, thereby altering the position of the acetabula within the pelvis and changing the pelvic incidence (cf. Fig. 3). Pelvic incidence (PI) is the angle between the line connecting the bicoxo–femoral axis and the middle of the sacral plateau with the perpendicular to the sacral plateau (Fig. 3). Importantly, it remains a constant value for each individual after adolescence. Surgical treatment should restore in the sagittal plane the pelvic incidence around normative data which is 55 ± 10.6 degree.
Roy-Camille classification for spinopelvic dissociation (types 1, 2, and 3 lesions). Pelvic incidence (PI) increases in type 2 and decreases in type 3.
Citation: EFORT Open Reviews 8, 5; 10.1530/EOR-23-0059
The SPD has a U-shape or H-shape and represents 3–5% of sacral fractures. Previous studies reported organ injuries in 42% of SPD patients, thoracic injuries in 37% of them, closed craniocerebral injuries in 21%, musculoskeletal injuries (including limbs) in 63%, an anterior pelvic fracture in 52%, other vertebral fractures in 47%, and spinal injuries in 16% patients (19).
Subsequently, Strange-Vognsen and Lebech described another kind of fracture, characterized by segmental comminution of the S1 vertebral body in case of axial trauma with the spine in a neutral position (20).Lehman described a fifth type (Type 5) which is a shear injury caused by direct loading mechanisms such as impalement or ballistic trauma (21). The injury morphology is the result of an extremely large blast force through the bottom of a vehicle. This causes a substantial superiorly directed force on the seated combatant which imparts a significant amount of energy directly to the bottom of the pelvis and sacrum (21).
The AO defined a classification which integrates the sacral lesion and the pelvic lesion (17). This classification system introduces injury patterns in order of stability, while simultaneously taking into consideration the degree of neurological deficit; three types A, B, and C. Type A injuries have no impact on the stability of the posterior pelvic ring or spine, given their distant location from the weight-bearing axis. Subtype A1 injuries are coccygeal compression or ligamentous avulsion fractures, subtype A2 nondisplaced transverse sacral fractures below the sacroiliac, and subtype A3 displaced fractures below the SIJ. Type B with subtypes B1, B2, and B3. Sacral B1 subtype fractures are central fractures that involve the spinal canal (zone III of Denis). Sacral B2 subtype fractures are represented by transalar fractures, which do not involve the sacral foramina or spinal canal (zone I of Denis). Sacral B3 subtype fractures are transforaminal in nature but do not involve the spinal (zone II of Denis). In fact, the progression of the subtype number in AO classification corresponds to the progression of instability and not to the frequency of neurological compromise. One should consider in type B the fracture line exiting proximally medially or lateral to the S1 articular process. In the latest, the instability is higher corresponding to a spinopelvic lesion. Type C with subtypes C1, C2, and C3 can disrupt the relationship between the spine and the pelvis. C0 subtype fractures are nondisplaced insufficiency sacral U-type variants. Sacral C1 subtype injuries are unilateral B subtype injuries in which the ipsilateral superior S1 facet is discontinuous with the medial sacrum. Sacral C2 subtype fractures are bilateral complete type B injuries without a transverse component. Sacral C3 subtype fractures are displaced U-type sacral fractures. The AO Spine Sacral and Pelvic Classification addresses the biomechanical stability of the posterior pelvic complex and spinopelvic stability, while also taking into consideration neurological status. Nevertheless, the AO classification has a moderate-to-strong reliability for fracture type and moderate reproducibility for subtypes (17, 22, 23).
In summary, apart from lumbosacral dislocation, one should integrate sacral or lumbosacral lesions into pelvic ring injuries since sacral fracture classifications, which are mainly descriptive, do not take into consideration pelvic instability. Regarding the pelvic ring fracture classifications, type A is a stable lesion, type B has horizontal instability, and type C has vertical instability. Commonly, H-type sacral fracture following high-energy trauma results from a symmetrical and medial impact giving a type C3 pelvic lesion or bilateral spinopelvic dissociation.
Which surgical treatment?
Pelvic clamp
This is an emergency procedure performed by the pelvic or trauma surgeon that closes the pelvic ring by doing an abdominal counterpression which stabilizes the bones in order to avoid bleeding. The clamp is placed close to the posterior aspect of the pelvic ring but needs intact iliac wings. The patient is in the supine position and percutaneous insertion is in the direction of the trochanteric. The pelvic clamp is a temporary procedure. It is converted into definitive fixation once the patient’s condition has been stabilized. Other options to close the pelvic ring include the use of a non-invasive pelvic belt for a few hours due to the risk of skin compression or an external fixator which may preclude subsequent anterior plating of the anterior ring.
Skeletal traction
This is a temporary procedure. A transfemoral skeletal may be placed to reduce the pelvic upward displacement or to prevent displacement before the definitive surgical fixation.
Iliosacral screw
This technique has been widely diffused since Routt described the procedure for sacroiliac opening (24). Trauma pelvic surgeons extended the technic to sacral fractures and to all types of sacroiliac lesions. The main advantage of this minimally invasive procedure is that it provides good biomechanical stability with a low infection rate. However, upper sacral dysplasia can exist in 30–50% of all sacrum, which leads to a more narrow and oblique screw pathway in S1 making screw placement difficult and significantly increasing the risk of iatrogenic vessel and nerve injury (25). This occurrence must be looked at during surgical planning in the preoperative pelvic CT scan. The risk of screw misplacement has been evaluated at 10% due to poor visualization under fluoroscopy or incomplete reduction. In such cases, iliosacral screws are contraindicated except if navigation can be used to secure screw placement. The use of navigation helps to secure screw placement.
Briefly, the goal is to implant percutaneously screws from the iliac wing to the sacrum and has been extensively described (4, 24): one screw above the S1 foramen and if possible, a second one between S1 and S2 foramen. The procedure is performed in a supine position under fluoroscopy and is easier and safer under navigation. The need of femoral traction is required to reduce the ascension of the pelvis. In case of reduction failure, an open reduction is mandatory. The entry point of the k-wire is crucial and visualizes on profile view. Then, the progression of the screw is checked on Inlet and Outlet view. The screw can overlap the median line or even go through the contralateral SI joint to add resistance to pull out. Pelvic surgeon and spine surgeon have the competence to perform the technique which is used in both specialties for other indications.
Lumboiliac fixation and sacroiliac fixation
Lumboiliac fixation
The technique is more of a spine surgery procedure as it is used for lumbopelvic arthrodesis. The patient is placed in the prone position and a midline incision over the lumbosacral area is made. Pedicle screws are inserted in L5 and in L4 if needed. Two options are possible for the pelvic fixation (Fig. 4).
Lumboiliac fixation: iliac screws (A) vs S2AI screws (B).
Citation: EFORT Open Reviews 8, 5; 10.1530/EOR-23-0059
Iliac screws:Distal screws are inserted between the two tables of the iliac wing aiming toward the greater trochanter. Navigation can help. Screw from 90 mm to 100 mm length and 7.5 mm gives a strong resistance. Screws are inserted under the level of the border of the iliac wing to avoid skin conflict. One rod is inserted between the spine and the iliac screw to create a solid construct acting against vertical shear forces. Compressing between these screws reduces the ascension of the iliac wing. The two distal screws in the iliac wing are connected together owing to add horizontal compression (Fig. 5). To avoid a transversal rod, two vertical rods are inserted and a transverse connector can add compression between vertical rods. This construct can be bilateral doing a triangular construct in the case of C3 lesions.
Example of H-type sacral fracture with lumbopelvic dissociation. (A) Pre-operative CT scan. (B) Post-operative CT scan. (C) Post-operative radiographs showing a bilateral lumboiliac fixation with transverse rod.
Citation: EFORT Open Reviews 8, 5; 10.1530/EOR-23-0059
S2AI screws:The S2AI screw was developed as an alternative to iliac screws. This screw starts at the 1 mm lateral and 1 mm inferior portion of the first sacral neural foramen, traverses the SIJ, and terminates in the ilium above the sciatic notch. The S2AI screw has been shown to originate 15 mm deeper than the iliac screw, leading to less instrumentation prominence and less muscle disinsertion and wound complication. In a meta-analysis, authors have shown that S2AI, used in lumbopelvic fixation for spinal deformity, minimizes revision surgery due to mechanical failure and wound complications (14.2 vs 27.9%, P < 0.001), decreases the rate of infections (2.6 vs 25.4%, P < 0.001), and minimizes screw prominence (1.8 vs 18.1%, P < 0.001) when compared with iliac bolts (26). Inline fixation obviates the need for a modular offset connector, which eliminates an additional point of failure. Biomechanical studies have demonstrated equivalence between the S2AI and iliac screw in lumbosacral spine fixation to the pelvis with regard to construct stiffness and failure (27). S2AI screws are inserted easily with navigation as iliac screws are easier to insert without navigation. Finally, insertion of S2AI screws can be difficult in case of a fracture line passing close to the entry point.
Spinopelvic fixation has been shown to be more biomechanically stable than iliosacral screws or transiliac plates (26, 28, 29). To add stability, a so-called triangular osteosynthesis technique (Fig. 7) combines the vertical component (lumbopelvic distraction osteosynthesis) with transverse fixation (iliosacral screw) (29, 30).
Example of a right unilateral lumbopelvic dissociation (Tile C1) (A) Pre-operative CT scan. (B) Post-operative CT scan. (C) Post-operative radiographs showing a unilateral lumboiliac fixation through Wiltse approach.
Citation: EFORT Open Reviews 8, 5; 10.1530/EOR-23-0059
Example of a Tile C bilateral pelvic fracture with bilateral sacral fracture. (A) Preoperative CT. (B) Postoperative radiographs showing a triangular lumbopelvic fixation with iliac screws and iliosacral screws.
Citation: EFORT Open Reviews 8, 5; 10.1530/EOR-23-0059
Less invasive and percutaneous procedure
These two procedures can be performed mini-invasively. A Wiltse approach, which gives more lateral access, avoids a large exposure and muscle disinsertion as seen in a midline approach and decreases bleeding with less infection rate. This approach allows the use of reduction maneuvers through a conventional open procedure.
Also, percutaneous fixation can be performed as a common procedure in spine surgery. Pedicular screws and iliac screws can be inserted percutaneously under fluoroscopy or navigation and the rod inserted with a percutaneous dedicated spine device. These percutaneous procedures may be contraindicated if the reduction is not obtained under traction because of the difficulties to add reduction maneuvers percutaneously (31, 32). Percutaneous procedures decrease blood loss and infection rates (33).
Sacroiliac fixation
If the S1 pedicle is intact and the sacral fracture line is distant from the pedicle, an S1 pedicle screw can be inserted to avoid fixation of the lumbosacral junction. This screw is connected to an ipsilateral iliac wing screw owing to close a horizontal opening (4). This procedure has the same effect as an iliosacral screw. To add compressive forces, a second screw in the iliac wing can be added and connected to the contralateral iliac wing (32). To avoid this second rod, an iliosacral screw can be inserted on the ipsilateral side. Also, ilioiliac percutaneous fixation with screws in the iliac wing and rod can be inserted percutaneously, but reduction must be obtained preoperatively or operatively under traction (32). These procedures are common in spine surgery procedures.
Plating
Pelvic surgeons have described plating from one iliac wing to another to achieve horizontal compression. This procedure does not act against vertical shear forces. As it needs a large muscular disinsertion, some authors tried to insert plates in a less invasive way (34). Nevertheless, this author reported a 30% of infection rate and recommended to remove the hardware because of distant pain and skin conflict. Transacral plate has insufficient mechanical strength and has been shown to be less stable than the iliosacral screw (28).
Lumbosacral arthrodesis
Fixation between the spine and the sacrum is a routine procedure for spine surgeons. Pedicles screws are inserted in L5 and S1 pedicles and connected with two rods. In case of disc disruption, to have stability and enhanced the rate of fusion, an interbody fusion is added with a cage filled up with bone. The cage can be inserted either through the spinal canal (PLIF) or through a transforaminal approach (TLIF) (35). If the cage cannot be possibly inserted from the posterior, an anterior interbody fusion (ALIF) can be performed. This option needs a two-step procedure, posterior reduction and fixation from the back followed by the anterior approach.
Nerve root decompression
This is a spine procedure. In case of sacral fracture through the foramen, one must check for sacral nerve root entrapment before doing compression maneuvers. In the case of cauda equina syndrome, decompression of the spinal canal is controversial as authors have shown no evidence of whether decompression has significant superiority in terms of long-term neurological recovery. Decompression should be performed in less than 24–72 h after injury but is not always feasible in polytraumatized patients (36) and in the presence of skin lesions or Morel-Lavallée hematoma (29). Yi and Hak demonstrated an improvement in neurologic deficit in 80% of surgically treated patients irrespective of the type of treatment (36). In 86% of patients with radicular compression, a partial recovery of sphincter function was reported after surgery with decompression and lumboiliac fixation; in the case of complete lesion or radicular avulsion, only 36% of patients showed partial recovery.
Indirect decompression is achieved by reducing the vertical displacement which elongates nerve roots and stabilizes the lumbosacral junction or by reducing a sacral kyphosis which will open the sacral canal.
Indications
Lumbosacral dislocation
In lumbosacral dislocation, a posterior L5/S1 arthrodesis is required. An interbody fusion is added in case of disc disruption. The first step is an open posterior reduction, with distraction and additional flexion to release the locked articular processes. After this procedure, the facets can be brought into a normal position by compression (11). In case of difficulty for reduction, a facetectomy can help, especially in case of pure dislocation (9, 11). In such trauma, one should be aware of associate radicular avulsion and the dura mater laceration which need reparation to avoid cerebrospinal fluid leakage (8, 10, 11). The avulsion of cauda equina fibers from the conus medullaris has been reported (37).
Type A pelvic fracture
In pelvic type A, fracture and distal fracture of the sacrum are treated nonoperatively.
Type B pelvic fracture
In pelvic type B, anterior plating is performed previously to close the anterior opening which helps closing the posterior lesion. To reduce the posterior horizontal component, a pelvic procedure such as iliosacral screwing is preferred in SIJ opening or sacral fracture. If iliosacral screwing is not feasible, another option is to perform a unilateral sacroiliac fixation through a Wiltse approach to close the posterior ring. Another procedure is a percutaneous fixation between the posterior iliac wings as we described previously (32). In case of incomplete reduction or important displacement or old lesion, an open reduction is mandatory. Fixation is performed with an iliac screw (in prone position) as in a spine procedure or a lumbosacroiliac fixation is performed.
Type C pelvic fracture
In pelvic type C lesions, the vertical ascension component of the pelvis can be reduced preoperatively and intraoperatively by transcondylar traction. Otherwise, for displacement of the iliosacral angle (vertical sacral fracture, or vertical lesion of the SIJ), one should undergo a spine procedure as a lumboiliac or sacroiliac procedure with a spine device for reduction and fixation (Fig. 5 and 6). An iliosacral screw may be added to achieve a triangular construct and allow weight-bearing (Fig. 7) (29).
In case of type B and type C lesions, the anterior fixation should be done prior to the posterior procedure to facilitate the posterior reduction.
Sacral fractures
In the case of sacral fracture, the treatment depends on the location of the fracture and the presence or not of neurological deficit. In the case of nerve roots compression related to sacral fracture displacement, open reduction with internal fixation and decompression are preferred. In the case of non-displaced sacral fracture and no neurologic compression, percutaneous iliosacral screwing is preferred to decrease pain and facilitate mobilization.
Spinopelvic dissociation
In case of SPD, surgical treatment aims to restore continuation between the spine and the pelvis. The two most commonly used surgical techniques are spinopelvic fixation and iliosacral screw fixation which were inserted unilaterally, bilaterally, or transsacrally. However, Schildhauer et al. have shown that triangular osteosynthesis provides significantly greater stability than iliosacral screws in in vitro cyclical loading conditions (28). Technically, the first step is to achieve reduction. Some authors achieve a reduction on the operating table, in a prone position with two transcondylar tractions. Elevation of the legs helps to reduce kyphosis displacement. Percutaneous iliosacral screws are then inserted.
To achieve a more biomechanical rigid construct and a more accurate reduction, an open reduction is mandatory with a lumbopelvic fixation as described previously. Pedicle screws are implanted into the vertebral body of L4 and L5 and two iliac screws are inserted distal from the transverse fracture. In the case of kyphosis, distraction is along the pre-curved longitudinal rods, this action can also reduce the rotation of the lower sacral segment through a hyper-extension manner. Then, lordotic restoration is performed with a Weber clamp placed at the lower sacral segment through dragging. In some cases, raising the lower extremities might benefit the reduction of kyphotic displacement. In an extension injury, longitudinal distraction is performed along the spinopelvic rod, thereby reducing the vertical displacement between the upper and lower sacral segments and reducing the posterior displacement. Restoration of a normal value of the pelvic incidence is the key guideline of the reduction. Decompression of the sacral canal is not mandatory since the reduction of the sacral displacement provides indirect decompression of the cauda equina nerve roots.
Complications – long-term results
More than life-threatening complications and neurological dysfunction, infection is the most common complication. Open reduction and fixation lead to 13–15% of infection rate in type C pelvic fracture (28). Infection in sacral plating has been reported to occur in 33% of cases (34). Percutaneous fixation decreases this rate due to less blood loss, no musculature disinsertion, devascularization, and denervation.
Irritation of the skin with the iliac screw head is not infrequent. To prevent this, iliac screws need to be inserted below the posterior spinous process or by making a bony resection to insert them below the plane of the iliac wing. Bellarbaba et al. reported 11% of reoperation for skin irritation and 45% of reoperation for complications after open surgery (infection, hematoma, etc.) (38).
The rate of iliosacral screw displacement has been reported to be 8–13% (38).
Non union has been reported to be 10–15%. Malunion can lead to leg discrepancy, low back pain, and abnormal gait with a poor quality of life (39, 40). Residual sacral and low-back pain persists in approximately 30% of patients and it takes at least 1 year after the trauma to recover a normal gait (41).
A vertical displacement causes differences in the lower extremities, abnormal motor gaits, and lower Majeed scores (42). Also, insufficient quality of the horizontal reduction results in a change in the lever arm of the peak moment of the hip, which causes greater work in terms of hip abduction, adduction, flexion, and extension in the affected side in patients with SPD (39).
Adelved et al. reported that among 13 patients with TLSD who were followed over an average period of 7.7 years, while the majority were able to perform the activities of daily living (85%), many exhibited the reduced quality of life in measures such as neurological deficits (85%), sexual dysfunction (62%), and altered bladder function (69%) (43).
Quality of life can be altered in these polytraumatized patients with multiple injuries and a neurological permanent deficit of cauda equina is crucial in this young patient.
Conclusions
Sacral fractures are rare in isolation, and patients with sacral fractures should be carefully monitored for possible associated spinal and/or pelvic ring injuries. In fact, sacral fractures must be included in pelvic trauma classifications and submitted to equivalent biomechanical principles of treatment. Although pelvic surgeons are more aware of this part, a majority of the fixation techniques to achieve this goal are from spine surgery experience. Depending on the surgeon’s training, country habitus, both pelvic surgeon and spine surgeon dealing with lumbosacral and sacral fractures must contribute together to understand the biomechanics, classifications, and complications associated to these particular injuries and apply the adapted treatment.
ICMJE conflict of interest statement
The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding statement
There are no funders to report for this submission.
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