Skip to main content

Sacropelvic fixation


The sacropelvis is not only an anatomically complex region but also a biomechanically unique zone transferring axial weights via the transitional lumbosacral junction and the pelvic girdle to the lower appendicular skeleton. When the sacral instrumentation alone is insufficient to achieve stability and solid arthrodesis across the lumbosacral junction, as in long-segment fusions, high-grade spondylolisthesis, deformity corrections, complex sacral/lumbosacral injuries, and neoplasms, sacropelvic fixation is indicated. Many modern sacropelvic fixation modalities outperform historical modalities, especially the conventionally open and percutaneous iliac and S2-alar-iliac screw (S2AI) fixation techniques. Novel screw insertion technologies such as navigation and robotics and modern screw designs aim to maximize the accuracy of screw placement and minimize complications. This review addresses the anatomy and biomechanics of the sacropelvic region as well as the indications, evolution, advantages, and disadvantages of various past and contemporary techniques of lumbosacral and sacropelvic fixation.

Introduction and overview

Pseudarthrosis and instrumentation failure at the lumbosacral junction continue to be a challenge for spine surgeons worldwide. These could be attributed to the unique anatomical, structural and biomechanical properties of the sacrum, the lumbosacral junction as well as the sacropelvis. Significant efforts have been made and continue to be exerted to overcome these complications to improve the clinical and radiological outcomes of lumbosacral and sacropelvic fixation techniques [1].

This review addresses the anatomy and biomechanics of this region as well as the indications, evolution, advantages, and drawbacks of various past and contemporary techniques of lumbosacral and sacropelvic fixation.

Anatomy and biomechanics

The lumbosacral junction is a critical motion segment that includes the fifth lumbar vertebra, the sacrum, and the intervening articulations, including the L5–S1 disc anteriorly and the facet joints posteriorly as well as the supporting ligaments and muscles. It is a transitional zone transferring weights from the axial to the appendicular skeleton through the pelvic girdle, being the focus of significant biomechanical stresses that may reach up to 100 N with some activities [2]. When fusions are extended to it, a strong lever arm is formed, transmitting flexion, extension, as well as torsional forces from the superjacent spine, thus increasing the risk of pseudarthrosis and instrumentation failure. The obliquity of the L5–S1 disc, the suboptimal fixation due to the paucity of cortical bone in the sacrum, and the relatively weak purchase of S1 pedicle screws all contribute to these risks.

Long-segment fixations (i.e., ≥ 4 levels) with sacral inclusion, especially when crossing the thoracolumbar junction, are more prone to failure than short-segment ones due to longer lever arm exertion by the proximal column on the distal sacral instrumentation. [1, 3, 4] (Fig. 1).

Fig. 1
figure 1

Long-segment fixations, including the lumbosacral junction, resulting in a strong cantilever effect making the construct more prone to failure [5]

The 80–20 rule of Professor Harms

The anterior spinal column transmits approximately 80% of the axial load, while the posterior column transmits only 20%. Fusions and instrumentations across the lumbosacral junction should biomechanically restore the anterior column load-sharing property; otherwise, failure will supervise [3].

The concept of the lumbosacral pivot point

McCord et al. [6] first defined this concept as the midpoint of the osteoligamentous column at the L5/S1 junction. As the fixation progresses anteriorly, the stability of the sacropelvic instrumentation increases [6].

Consequently, when stability is a concern, iliac or S2AI screws are considered the best sacropelvic fixation modality [3, 4] (Fig. 2).

Fig. 2
figure 2

Different options for sacropelvic fixation in relation to the pivot point and adjacent neurovascular structures [7]

Pelvic parameters

The relationship of the spine to the pelvis is the key determinant of the sagittal spinal alignment and is analyzed by the following parameters: the pelvic tilt (PT), the pelvic incidence (PI), and the sacral slope (SS) [8]. The relationship between the above-mentioned parameters is determined by the following equation [9]: PI = PT + ‏SS. In the context of sacral/sacropelvic fixation, these parameters must be assessed preoperatively in order to achieve/restore spinopelvic harmony both clinically and radiologically [5, 10] (Fig. 3).

Fig. 3
figure 3

PT (green line) is defined as the angle between the vertical reference line and the line connecting the femoral head to the midpoint of the sacral plate. PI (red line) is defined by the angle between the line perpendicular to the sacral plate midpoint and another line connecting the sacral plate midpoint to the femoral head. SS (purple line) is the angle formed between the sacral endplate and the horizontal reference line [5]

The zone concept of O'Brien [11]and options for arthrodesis

Based on this concept, there are three zones of the sacropelvic unit available for sacral/sacropelvic fixation: [1, 3, 4] (Fig. 4).

  • Zone 1: S1 body and upper part of the sacral alae.

  • Zone 2: lower part of the sacral alae, the middle and lower sacrum, and the coccyx.

  • Zone 3: Bilateral ilia.

Fig. 4
figure 4

a The sacropelvic zones of O'Brien [11]. b Sacropelvic fixation options in relation to McCord's pivot point and zones of O'Brien [4]

Stability increases when fixation goes caudally utilizing more anchor points, and the best is through zone 3, with fixation extending beyond the pivot point.

There are plenty of options available for sacral/sacropelvic fixation, with sacral pedicle, iliac and S2AI screw fixation techniques being the most commonly used nowadays.

Below is a detailed list of these options, including methods of historical value only.

Zone I options

  • S1 pedicle screws.

  • S1 tricortical pedicle screws.

  • L5–S1 transfacet pedicle screws (TFPS).

  • Transdiscal fixation.

  • Transsacral fixation.

  • Sacral sublaminar wires, hooks, and cables.

  • Dunn-McCarthy S-rod fixation.

Zone II options

  • Sacral alar screws.

  • Intrasacral Jackson rod fixation.

Zone III options

  • Iliac screw fixation.

  • Maximum width (MW) spinopelvic construct.

  • The T-construct.

  • S2AI screw fixation.

  • S1-ALAR-ILIAC screws (S1AI).

  • Combined S1AI and S2AI screws.

  • S3-ALAR-ILIAC screws (S3AI)

  • Iliosacral screw (ISS) fixation.

  • Transiliac (sacral) bar and spinopelvic transiliac fixation (STIF).

  • Galveston L-rod fixation.

Indications of sacropelvic fixation

When sacral pedicle screws are not sufficient to achieve stability and solid arthrodesis across the lumbosacral junction, sacropelvic fixation is indicated as in:

  • Long-segment fixation (i.e., ≥ 4 levels) with sacral inclusion especially when crossing the thoracolumbar junction and also when pelvic obliquity should be corrected as during deformity corrections.

  • High-grade spondylolisthesis stabilization with or without reduction.

  • Lower lumbar spine osteotomies and revisions entailing potential destabilizations.

  • Spinopelvic dissociation, sacral fractures, and reconstruction of the sacropelvic unit after sacrectomy as in sacral tumors.

  • Osteopenic and osteoporotic patients to provide more anchoring points for solid arthrodesis.

  • Multimodal plans in the management of extensive neoplastic and inflammatory lesions of the lower lumbar spine, the sacrum, and the pelvis [1, 3, 4].

Sacral pedicle screws

After entry point preparation at the base of the S1 cranial facet, a pedicle probe is introduced perpendicularly with medial angulation and aimed toward the sacral promontory. In order to avoid loosening of unicortical screws, controlled bicortical (penetration of the anterior cortex) and even tricortical (with S1 endplate penetration at the promontory) screw purchase could be utilized. Even though tricortical screws have twice the insertional torque of bicortical screws, [12] the failure rate with long fusions is 44% [13, 14]. Being posterior to the pivot point with narrow safety zones of insertion, S2 pedicle screws have no statistically significant effect on construct strength [1, 3, 6, 15] (Fig. 5a).

Fig. 5
figure 5

S1 screw options. a S1 pedicle screw and b S1 alar screw [16]

Laterally directed sacral screws (alar screws)

The S1 alar screw entry is just distal to the S1 cranial facet parallel with the dorsal S1 foramen, whereas that of S2 is between the dorsal S1 and S2 foramina. The trajectory is ideally 35° laterally and parallels with the S1 endplate. The controlled bicortical purchase is desired. Aside from the narrow safety zones of insertion, pseudarthrosis and poor clinical outcomes are common [1, 3, 6, 14, 15] (Fig. 5b).

Structures endangered with screw placement through the anterior cortex of the sacrum

Except for the middle sacral vessels, no neurovascular structures are jeopardized by medial angulation of S1 pedicle screws and strict direction toward the promontory. Straightforward trajectories put the L5 nerve root at risk where it crosses the anterior sacrum. Lateral S1 screws endanger the lumbosacral plexus, the internal iliac vessels, and the sacroiliac (SI) joint. Lateral S2 screws may endanger the nearby colon [3].

L5–S1 transfacet pedicle screws (TFPS)

This technique of lumbosacral stabilization and fixation entails passing the pedicle screw through the L5–S1 facet into the S1 pedicle providing multiple anchoring points to obtain short segments and more solid constructs than classic pedicle screw rod fixation. In an in vitro study conducted by Chin et al. [17], TFPS achieved better immediate postoperative stability than standard pedicle screws at L5–S1 level. They recommended further validation of these results via biomechanical and clinical studies [17] (Fig. 6).

Fig. 6
figure 6

Bilateral TFPS at L5–S1. A Anterior–posterior view, B Lateral view [17]

Transdiscal fixation

This type of fixation introduced in 1994 by Abdu et al. [18] is sometimes utilized in high-grade spondylolisthesis. Screws passing from the sacral pedicles via the L5–S1 disc space and into L5, improve construct stability and fusion rates with a good clinical outcome. The triangular configuration of the construct (i.e., created by the transdiscal screw, the L5 screw, and the rod) is sometimes referred to as "delta" fixation resembling the Greek letter Δ [18] (Fig. 7).

Fig. 7
figure 7

Transdiscal or "delta" fixation [19]

Transsacral fixation

In order to stabilize the posterior pelvic ring, this method is most commonly utilized for longitudinal sacral fractures including type B and minimally displaced type C fractures. Under fluoroscopic guidance, one or more screws are advanced and anchored in the sacral bodies or the contralateral ilium (i.e., transsacral-transiliac screws). When the sacral ala is not comminuted, lag screws of sufficient length can be utilized; otherwise, two or more static screws in the uninvolved sacral side are preferred. These screws can be combined with other modalities of spinopelvic fixation. The main limitations of these techniques are closed reduction for severely displaced fractures and limited stability [3].

Sacral sublaminar wires, hooks, and cables

These methods lack anchoring strength and rigidity and may be reverted to in combination with pelvic screws when anatomy is disturbed as in revision cases, keeping in mind the poor pullout strength and high failure rate [1, 6, 11, 20].

Dunn-McCarthy S-rod fixation

In 1989, this technique was developed mainly for myelodysplastic pediatric patients and entails an S-shaped rod passing over the ala of the sacrum after releasing the iliolumbar ligament [21,22,23]. It provides a sufficient lever arm action against flexion forces being the most useful in non-ambulatory patients with neuromuscular deformities. On the contrary, it provides less resistance to distraction, rotation, and lateral bending forces being less suitable in ambulatory patients [11]. In a retrospective review of 67 patients with neuromuscular deformity, it demonstrated a 53% correction of pelvic obliquity with no significant demise at 6 years [22, 24] (Fig. 8).

Fig. 8
figure 8

Dunn and McCarthy S-rods fixation [24]

The Jackson intrasacral rods

Rods—not crossing the SI joint—are vertically inserted into sufficient alae of the sacrum from S1 to S2 and then, connected to the S1 pedicle screws and above. Bilateral pelvic fixation with S1 pedicle screws appears biomechanically stronger [1, 25] (Fig. 9).

Fig. 9
figure 9

Jackson intrasacral rods [26]

The Galveston technique

This technique entails submuscular iliac rod insertion at the posterior superior iliac crest crossing the SI joint [6, 27]. The trajectory is 30–35° caudally and 20–25° laterally. The micromovement-induced windshield-wiper effect may supervene, necessitating implant removal. [1, 28, 29] (Fig. 10).

Fig. 10
figure 10

Galveston L-rod fixation [24]

Transiliac (sacral) bar and spinopelvic transiliac fixation (STIF)

Sacral bar fixation entails rod(s) spanning the sacrum that passes horizontally from ilium to ilium. It is rarely used nowadays in the context of sacral fractures and complex lumbosacral/sacropelvic reconstructions. STIF technique was introduced by King et al. [30] consisting of L-shaped rods with threaded ends, washers, and locking nuts. The rod threads are inserted through the posterior ilium at the level of S2. The rods are then linked just proximal to the right angle of the bend followed by tightening the nuts over the washer and the ilium compressing the SI joints on each side. At long-term follow-up, STIF provides 67% correction of the pelvic obliquity, with only a 7.4% pseudarthrosis rate [3, 24, 31] (Fig. 11).

Fig. 11
figure 11

STIF system [24]

Iliosacral screws (ISS)

These are directed from the ilium's outer cortex, across the inner table, and then include the S1 pedicle dorsal to the SI joint [32]. Then, special connectors are utilized to accommodate the longitudinal rods to complete the construct. Extensive soft tissue dissection and dorsal iliosacral ligament resection are usually required. Some studies had yielded good fusion rates [33, 34], but others had a failure rate of 28% [1, 13] (Fig. 12).

Fig. 12
figure 12

ISS fixation [35]

Iliac screws (iliac bolts)

This relatively new method of fixation entails the independent placement of screws in the ilium, and special connectors are then used to connect them to the longitudinal rods. Iliac screws have superior pullout strength and fusion rates when compared with the previously mentioned modalities, especially the Galveston rods [1, 28, 36,37,38,39,40].

The conventional open iliac screws insertion technique

The overlying cortex is breached at the level of S2–S3, about 1 cm from the distal ilium, after the posterior superior iliac spine (PSIS) is palpated and exposed with Bovie cautery and Cobb retractors, taking into consideration the later on prominence of the implant. A pedicle probe is then introduced at 25° lateral to the sagittal plane and 30–35° caudal to the transverse plane aimed toward the anterior inferior iliac spine (AIIS). A fluoroscopic check or finger palpation of the sciatic notch may guide the screw path. The medial or lateral cortical breach is checked via a blunt probe with determination of the screw length which is commonly 8–10 mm in diameter and 80–100 mm in length. Finally, the iliac screw is inserted and then secured to the longitudinal rod of the main construct via a modular connector. There are modified techniques for medially placing the screw head to help decrease the prominence of the implant and avoid the use of connectors. There is also the minimally invasive percutaneous iliac screw insertion technique utilizing fluoroscopy to visualize the iliac teardrop as a guide for screw placement [3, 41] (Fig. 13).

Fig. 13
figure 13

Open iliac screw insertion technique A Entry point preparation and trajectory. B conventional iliac screws are connected to the rods via modular connectors. C A modified technique minimizes screw prominence by medializing the screw head obviating the need for modular connectors [42, 43]

Maximum width (MW) spinopelvic construct

This technique was developed by Arlet et al. [44] in 1999 for the correction of pelvic obliquity in patients with neuromuscular deformity. It entailed combining iliosacral and iliac screws, in an MW construct, to increase the stabilization at the lumbosacral junction. [45] The construct constituted an “M” and a “W” on posteroanterior radiograph and axial reconstruction images, respectively. Carroll et al. [46] reported an approximate reduction of 61% in pelvic obliquity at 3 months of follow-up [24] (Fig. 14).

Fig. 14
figure 14

MW spinopelvic construct [24]

The T-construct

This method has been used successfully for deformity correction in patients with neuromuscular scoliosis. A transverse rod is fixed to S1 and iliac screws resulting in a more stable T-shaped configuration of the construct [47,48,49] (Fig. 15).

Fig. 15
figure 15

The T-Construct [49, 50]

S2-alar-iliac (S2AI) screws

This is a contemporary technique of SI arthrodesis that crosses the SI joint. The screw entry is 2–4 mm lateral and 4–8 mm distal to the S1 dorsal foramen [51]. After entry point preparation, a 2.5 mm drill is advanced with a lateral trajectory of about 40° to the horizontal plane and a caudal trajectory of 20–30° depending on the PT. Fluoroscopic guidance is beneficial, and the trajectory should aim toward the AIIS being always above the greater sciatic notch. To avoid breaking the drill after crossing the SI joint, it is changed to a 3.2 mm drill. A teardrop fluoroscopic view ensures being within the confines of the iliac cortex. An 80–90 mm in length and 8–10 mm in diameter polyaxial screw is introduced. Unlike iliac screws, this technique avoids the implant prominence and obviates the need for connectors [51, 52]. This technique has the lowest overall complication rate among other techniques, but long-term follow-up is required, particularly to evaluate its adverse effects on the SI joint [1, 53, 54] (Fig. 16).

Fig. 16
figure 16

Open S2AI screw insertion technique. A The entry point. BD Coronal, sagittal, and axial views, respectively, of the final trajectory. E The connection of the S2AI screws to the longitudinal rods completes the construct [3]

The minimally invasive percutaneous S2AI screw insertion technique

S2AI screws could be placed percutaneously and combined with percutaneous fixation of the lumbar spine when indicated. The approach entails a 3 cm skin incision and the entry point aligned with the lateral margin of the S1 foramen and midway between the S1 and S2 foramina. The trajectory is identical to that of the open procedure. The Jamshidi needle is introduced and angled toward the AIIS above the sciatic notch. Standard anteroposterior (AP), pelvic inlet, and teardrop fluoroscopic views are utilized. The needle is advanced within the confines of the teardrop and across the SI joint into the ilium, followed by guidewire placement, tapping, and screw insertion [3] (Figs. 17 and 18).

Fig. 17
figure 17

The creation of the "teardrop" view. a The red line represents the contour of the inner table and sciatic notch creating the medial half of the "teardrop". The black line represents the contour of the anterior ilium that creates a portion of the teardrop. b The blue line represents the contour of the opposite lateral half of the "teardrop". The ideal "teardrop" view results from an overlap of the blue, red, and black lines [41]

Fig. 18
figure 18

The percutaneous S2AI screw insertion technique. A Entry point determination. Left: Localization of the S1 foramen using a standard probe. The white arrows refer to the S1 upper endplate, the SI joint, and the acetabulum. Middle: Localization of the S2 foramen. Right: The entry point (white star) is 10 mm lateral to the midpoint between S1 and S2 foramina. B Trajectory verification. Left: The probe is advanced keeping its tip in the center of the (teardrop) identified on the oblique obturator view. Middle: In the anteroposterior view, the probe is directed laterally in the transverse plane and caudally in the sagittal plane. Right: The screw is advanced in the direction of the AIIS (white star) (From Yilmaz E, Abdul-Jabbar A, Tawfik T, et al. S2 alar-iliac screw insertion: Technical note with pictorial guide. World Neurosurg 2018;113:296–301, Fig. 2, p. 297; Fig. 4, p. 298.) [55]

Risks associated with iliac and S2AI screw fixation

Due to their superficial location and use of connectors, iliac screws are more commonly associated with implant prominence than S2AI screws. Screw misplacement may injure the superior gluteal artery, the internal iliac vessels, the sciatic nerve, the obturator nerve, the lumbosacral plexus, or the cluneal nerves. Hip joint violation and chondral injury are feasible by misplaced or long screws. SI joint pain and dysfunction are commonly encountered but not properly estimated [3].

S2AI screws versus iliac screws

S2AI screws outperform iliac screws as reported in many studies in the literature, especially concerning revision and failure rates, wound problems as well as pain, and return to work activities [56, 57]. Ilyas et al. [58] conducted a clinical and radiological comparison between iliac and S2AI screws and reported that using S2AI screws had statistically better outcomes with respect to implant loosening, and revision surgery because of implant loosening, acute infections, delayed wound complications, and late pain. Keorochana et al. [59] came to the conclusion that both techniques have the same outcomes in the pediatric and adult populations and when pain scores are considered, but with superior complication and revision rates associated with iliac screws. Sponseller et al. [60] concluded that S2AI screws are better at correcting pelvic obliquity than iliac screws.

Better biomechanical outcomes and complication rates were observed with S2AI screws in a meta-analysis conducted by De la Garza Ramos et al. [61]. Hasan et al. [62] conducted another meta-analysis focusing mainly on the post-operative complications and concluded that lower profile S2AI screws outperformed iliac screws but with more concerns regarding SI joint violation resulting in pain and dysfunction.

Mazur et al. [63] suggested that S2AI screws have greater purchase and obviate the need for cumbersome connectors. Perrault et al. [64] illustrated that the use of connectors augments the loads and stresses on iliac screws and that the toggle movement on screws is decreased by 17% if a sacral screw entry is applied instead of the standard iliac crests. Lee et al. [65] revealed that S2AI screws have low implant failure rates and that cross-linkage with iliac screws reinforces the construct decreasing implant failure.

In a cadaveric biomechanical study conducted by Hoernschemeyer et al. [66], less stiffness in iliac screws was reported, but with no statistical significance [4].

S1-alar-iliac (S1AI) screws

They are rarely reverted to as a salvage option in cases with a failed promontory screw. The entry is identical to that of the S1 pedicle. The entry point should not be too lateral or too medial. The trajectory is 35–45° caudally and 20° horizontally in the coronal plane targeting the ipsilateral greater trochanter [4, 67].

Combined S1AI and S2AI screws

This is a salvage technique first described by Mattei et al. in 2013 and was reverted to in cases of pseudarthrosis, complex deformities, and failed instrumentation to gain better fixation and union [68].

S3-alar-iliac (S3AI) screws

This emerging technique was first described by Mattei et al. in 2020 as a salvage procedure for complex deformities. The entry is located at the midpoint of S2 and S3 foramina, 2 mm medial to the lateral iliac crest. Due to its proximity to the sciatic notch, navigation systems were warranted over the freehand for such screws [69].

Advances in screw design

For better fixation in and around the SI region, emerging screw designs are available. Dual outer diameter (DOD) screws: Their distal diameter is designed to penetrate deeply into bone without cortical violation providing better purchase in the sacrum, ilium, and osteoporotic bones via dual-diameter and threading (Fig. 19a).

Fig. 19
figure 19

a DOD screws. b Closed head polyaxial, monoaxial, and angled monoaxial DOD screws [4]

Closed head DOD screws: These polyaxial, monoaxial, or angled monoaxial screws, are primarily designed for iliac fixation having better purchase in cancellous bone. They taper distally for better navigation within the confines of the cortex with maintained core diameter. The closed heads provide better security, and their profile accepts round, faceted, and D-shaped offsets [4] (Fig. 19b).

Navigation and robotics

Navigation systems have emerged for accurate and safe screw placement including pedicle and S2AI screws. A stereotactic frame mounted on the spinous process of the lumbar vertebrae is utilized followed by determination of the screw entry on CT scan pre or intraoperatively. Screw trajectory and size are determined based on the CT scan. K wire and Jamshidi needle are then introduced followed by screw insertion. In a navigation-guided series of 36 S2AI screws conducted by Ray et al. [70], there was a single anterior breach that necessitated repositioning.

Robotics is recently applied, and it requires a thin cut (1 mm) CT scan uploaded to the planning software preoperatively. Individual segmentation of the vertebrae keeps the registration unaltered. The screw entry and trajectory are preplanned. Fluoroscopic images are then taken and synchronized with the preoperative CT scan. The robot is then positioned, and the predetermined arms are fixed to it followed by drilling and screw placement [4].

Bederman et al. [71] inserted 31 robotically guided S2AI screws; 20 of them penetrated the distal ilium by < 2 mm, 1 screw by 2–4 mm, and 10 screws by ≥ 4 mm. They encountered no violations proximally, to the sciatic notch or the pelvis. No neurovascular complications were detected. Shillingford et al. [72] reported no significant difference between the freehand and the robotic techniques in terms of accuracy and complications [4].


Although there are numerous techniques for sacropelvic fixation, some of them are only of historical interest. Iliac and S2AI screw fixation are considered the most commonly utilized modalities nowadays with better clinical and radiological outcomes in favor of the latter. Both could be placed percutaneously and combined with percutaneous fixation of the lumbar spine. Navigation and robotics are novel techniques that aim to maximize the accuracy of screw placement and minimize complications. Spine surgeons dealing with complex spine deformities and reconstructions should master the different modalities of sacropelvic fixation and be aware of the potential risks and complications associated with them. Surgical decision-making should be individualized for every patient, and the surgeon's experience should be considered.

Availability of data and materials

Not applicable.



Anterior inferior iliac spine


Dual outer diameter


Iliosacral screw


Maximum width


Pelvic tilt


Pelvic incidence


Posterior superior iliac spine


Sacral slope




S1-alar-iliac screws


S2-alar-iliac screws


S3-alar-iliac screws


Spinopelvic transiliac fixation


Transfacet pedicle screws


  1. Kebaish KM. Sacropelvic fixation: techniques and complications. Spine (Phila Pa 1976). 2010;35(25):2245–51.

    Article  Google Scholar 

  2. Potter BK, Kuklo TR, O’Brien MF. Sacro-iliac fixation for treatment of high-grade spondylolisthesis. Semin Spine Surg. 2004;16(2):119–25.

    Article  Google Scholar 

  3. Kebaish KM, Devlin VJ. Instrumentation and fusion at the lumbosacral junction and pelvis. Spine Secrets E-Book. 2020;23:298.

    Google Scholar 

  4. Nanda A, Manghwani J, Kluger PJ. Sacropelvic fixation techniques—current update. J Clin Orthop Trauma. 2020;11(5):853–62.

    Article  Google Scholar 

  5. El Dafrawy MH, Raad M, Okafor L, Kebaish KM. Sacropelvic fixation: a comprehensive review. Spine Deform. 2019;7(4):509–16.

    Article  Google Scholar 

  6. McCord DH, Cunningham BW, Shono Y, Myers JJ, McAfee PC. Biomechanical analysis of lumbosacral fixation. In: Yonenobu K, Ono K, Takemitsu Y, editors. Lumbar Fusion and Stabilization. Tokyo: Springer; 1993.

    Chapter  Google Scholar 

  7. Polly DW, Latta LL. Spinopelvic fixation biomechanics. Semin Spine Surg. 2004;16(2):101–6.

    Article  Google Scholar 

  8. Schwab F, Lafage V, Patel A, Farcy JP. Sagittal plane considerations and the pelvis in the adult patient. Spine. 2009;34:1828–33.

    Article  Google Scholar 

  9. Boulay C, Tardieu C, Hecquet J, Benaim C, Mouilleseaux B, Marty C, et al. Sagittal alignment of spine and pelvis regulated by pelvic incidence: standard values and prediction of lordosis. Eur Spine J. 2006;15(4):415–22.

    Article  CAS  Google Scholar 

  10. Schwab F, Patel A, Ungar B, Farcy JP, Lafage V. Adult spinal deformity-postoperative standing imbalance: How much can you tolerate? An overview of key parameters in assessing alignment and planning corrective surgery. Spine (Phila Pa 1976). 2010;35(25):2224–31.

    Article  Google Scholar 

  11. O’Brien MF, Kuklo TR, Lenke LG. Sacropelvic instrumentation: anatomic and biomechanical zones of fixation. Semin Spine Surg. 2004;16(2):76–90.

    Article  Google Scholar 

  12. Lehman RA, Kuklo TR, Belmont PJ, Andersen RC, Polly DW. Advantage of pedicle screw fixation directed into the apex of the sacral promontory over bicortical fixation: a biomechanical analysis. Spine (Phila Pa 1976). 2002;27(8):806–11.

    Article  Google Scholar 

  13. Camp JF, Caudle R, Ashmun RD, Roach J. Immediate complications of cotrel-dubousset instrumentation to the sacro-pelvis: a clinical and biomechanical study. Spine (Phila Pa 1976). 1990;15(9):932–41.

    Article  CAS  Google Scholar 

  14. Devlin VJ, Boachie-Adjei O, Bradford DS, Ogilvie JW, Transfeldt EE. Treatment of adult spinal deformity with fusion to the sacrum using CD instrumentation. J Spinal Disord. 1991;4(1):1–14.

    CAS  Google Scholar 

  15. Zindrick MR, Wiltse LL, Widell EH, Thomas JC, Holland WR, Field BT, et al. A biomechanical study of intrapeduncular screw fixation in the lumbosacral spine. Clin Orthop Relat Res. 1986;203:99–112.

    Article  Google Scholar 

  16. Kim DH, Vaccaro AR, Dickman CA, Cho D, Lee S, Kim I. Surgical anatomy & techniques to the spine. Amsterdam: Elsevier/Saunders; 2013.

    Google Scholar 

  17. Chin KR, Pencle FJ, Newcomb AG, Reis MT, Reyes PM, Malhotra D, Yu WD, Bruce CA, Crawford NR. Biomechanical comparison of same size transfacet screws versus pedicle screws across the L5–S1 native disc. West Indian Med J. 2017;66(3):416–23.

    Google Scholar 

  18. Abdu WA, Wilber RG. Pedicular trans vertebral screw fixation of the lumbosacral spine in spondylolisthesis: a new technique for stabilization. Spine (Phila Pa 1976). 1994;19(6):710–5.

    Article  CAS  Google Scholar 

  19. Delgado-Fernández J, Frade-Porto N, Blasco G, González-Tarno P, Gil-Simoes R, Rivas PP, et al. Long term outcome and fusion rate of transdiscal fixation for L5–S1 high grade spondylolisthesis. Clin Neurol Neurosurg. 2021;208(June):1–8.

    Google Scholar 

  20. Baldwin NG. Complex lumbosacropelvic fixation techniques. In: Spine surgery: techniques, complication avoidance, and management. 1999. p. 1111–9.

    Google Scholar 

  21. McCarthy RE, Dunn H, McCullough FL. Luque fixation to the sacral ala using the dunn–mcCarthy modification. Spine (Phila Pa 1976). 1989;14(3):281–3.

    Article  CAS  Google Scholar 

  22. McCarthy RE, Bruffett WL, McCullough FL. S rod fixation to the sacrum in patients with neuromuscular spinal deformities. Clin Orthop Relat Res. 1999;364:26–31.

    Article  Google Scholar 

  23. Warner WC, Fackler CD. Comparison of two instrumentation techniques in treatment of Lumbar Kyphosis in myelodysplasia. J Pediatr Orthop. 1993;13(6):704–8.

    Article  Google Scholar 

  24. Dayer R, Ouellet JA, Saran N. Pelvic fixation for neuromuscular scoliosis deformity correction. Curr Rev Musculoskelet Med. 2012;5(2):91–101.

    Article  Google Scholar 

  25. Lebwohl NH, Cunningham BW, Dmitriev A, Shimamoto N, Gooch L, Devlin V, et al. Biomechanical comparison of lumbosacral fixation techniques in a calf spine model. Spine (Phila Pa 1976). 2002;27(21):2312–20.

    Article  Google Scholar 

  26. Jackson RP, McManus AC. The iliac buttress: a computed tomographic study of sacral anatomy. Spine (Phila Pa 1976). 1993;18(10):1318–28.

    Article  CAS  Google Scholar 

  27. Devlin VJ. Biomechanics and surgical principles of long fusions to the sacrum. Spine State Art Rev. 1996;10:515–44.

    Google Scholar 

  28. Gau YL, Lonstein JE, Winter RB, Koop S, Denis F. Luque-galveston procedure for correction and stabilization of neuromuscular scoliosis and pelvic obliquity: a review of 68 patients. J Spinal Disord. 1991;4(4):399–410.

    Article  CAS  Google Scholar 

  29. Broom MJ, Banta JV, Renshaw TS. Spinal fusion augmented by luque-rod segmental instrumentation for neuromuscular scoliosis. J Bone Jt Surg Am Vol. 1989;71(1):32–44.

    Article  CAS  Google Scholar 

  30. King AG, Thomas KA, Zembo MM. Analysis of the STIF technique for spino-pelvic fixation. Orthop Trans. 1996;20:128–9.

    Google Scholar 

  31. King AG, Thomas KA, Eiserloh HL, Mills TE, Pisciotta DN. Analysis of the STIF technique for spino-pelvic fixation: clinical results in 19 patients with neuromuscular scoliosis. J Pediatr Orthop. 2000;20(5):667–76.

    Article  CAS  Google Scholar 

  32. Ebraheim NA, Xu R, Biyani A, Nadaud MC. Morphologic considerations of the first sacral pedicle for iliosacral screw placement. Spine (Phila Pa 1976). 1997;22(8):841–6.

    Article  CAS  Google Scholar 

  33. Farcy JPC, Margulies JY. Iliosacral screw fixation. In: Lumbosacral and spinopelvic fixation. Philadelphia: Lippincott Williams and Wilkins; 1996. p. 601–9.

    Google Scholar 

  34. Miladi LT, Ghanem IB, Draoui MM, Zeller RD, Dubousset JF. Iliosacral screw fixation for pelvic obliquity in neuromuscular scoliosis: a long-term follow-up study. Spine (Phila Pa 1976). 1997;22(15):1722–9.

    Article  CAS  Google Scholar 

  35. Banerjee R, Brink P, Cimerman M, Pohlemann T, Tomazevic M. Iliosacral screw for SI joint [Internet]. Surg Ref. Available from:

  36. Schwend RM, Sluyters R, Najdzionek J. The pylon concept of pelvic anchorage for spinal instrumentation in the human cadaver. Spine (Phila Pa 1976). 2003;28(6):542–7.

    Article  Google Scholar 

  37. Bridwell KH, Kuklo T, Edwards CC, Lenke LG, Berra A. Sacropelvic fixation. Memphis: Medtronic Sofamor Danek USA; 2004.

    Google Scholar 

  38. Kuklo TR, Bridwell KH, Lewis SJ, Baldus C, Blanke K, Iffrig TM, et al. Minimum 2-year analysis of sacropelvic fixation and L5–S1 fusion using S1 and iliac screws. Spine (Phila Pa 1976). 2001;26(18):1976–83.

    Article  CAS  Google Scholar 

  39. Saer EH, Winter RB, Lonstein JE. Long scoliosis fusion to the sacrum in adults with nonparalytic scoliosis: an improved method. Spine (Phila Pa 1976). 1990;15(7):650–3.

    Article  Google Scholar 

  40. Rosner MK, Ondra SL. Sacropelvic fixation in adult deformity. Semin Spine Surg. 2004;16(2):107–13.

    Article  Google Scholar 

  41. Jorgensen A, Shah D, Bates T. Percutaneous lumbopelvic fixation. Semin Spine Surg. 2021;33(1): 100850.

    Article  Google Scholar 

  42. George SG, Lebwohl NH, Pasquotti G, Williams SK. Percutaneous and open iliac screw safety and accuracy using a tactile technique with adjunctive anteroposterior fluoroscopy. Spine J. 2018;18(9):1570–7.

    Article  Google Scholar 

  43. Moshirfar A, Kebaish KM, Riley LH. Lumbosacral and spinopelvic fixation in spine surgery. Semin Spine Surg. 2009;21(1):55–61.

    Article  Google Scholar 

  44. Arlet V, Marchesi D, Papin P, Aebi M. The “MW” sacropelvic construct: an enhanced fixation of the lumbosacral junction in neuromuscular pelvic obliquity. Eur Spine J. 1999;8(3):229–31.

    Article  CAS  Google Scholar 

  45. Arlet V. Comments on the article: MW construct in fusion for neuromuscular scoliosis (Eben A. Carroll, Jeffrey Scott Shilt, Laura Jacks). Eur Spine J. 2007;16:379–80.

    Article  Google Scholar 

  46. Carroll EA, Shilt JS, Jacks L. MW construct in fusion for neuromuscular scoliosis. Eur Spine J. 2007;16(3):373–7.

    Article  Google Scholar 

  47. Bouyer B, Bachy M, Zahi R, Thévenin-Lemoine C, Mary P, Vialle R. Correction of pelvic obliquity in neuromuscular spinal deformities using the “T construct”: results and complications in a prospective series of 60 patients. Eur Spine J. 2014;23(1):163–71.

    Article  Google Scholar 

  48. Zahi R, Thévenin-Lemoine C, Rogier A, Constantinou B, Mary P, Vialle R. The, “t-construct” for spinopelvic fixation in neuromuscular spinal deformities. Preliminary results of a prospective series of 15 patients. Child’s Nerv Syst. 2011;27(11):1931–5.

    Article  Google Scholar 

  49. Vetrile MS, Kuleshov AA, Aganesov NA, Zakharin VR. Spinopelvic fixation: indications, anatomical and biomechanical aspects and historical development of methods. Hir Pozvonoc. 2021;18(3):100–10.

    Article  Google Scholar 

  50. Bachy M, Kabbaj R, Bouyer B, Mary P, Vialle R. Extensiones a la pelvis de las osteosintesis raquideas. EMC-Técnicas Quirúrgicas-Ortopedia y Traumatología. 2014;6(2):1–6.

    Article  Google Scholar 

  51. O’Brien JR, Yu WD, Bhatnagar R, Sponseller P, Kebaish KM. An anatomic study of the S2 iliac technique for lumbopelvic screw placement. Spine (Phila Pa 1976). 2009;34(12):E439–42.

    Article  Google Scholar 

  52. Chang TL, Sponseller PD, Kebaish KM, Fishman EK. Low profile pelvic fixation: anatomic parameters for sacral alar-iliac fixation versus traditional iliac fixation. Spine (Phila Pa 1976). 2009;34(5):436–40.

    Article  Google Scholar 

  53. Kebaish K, Ter GAP, Mohamed A, Zimmerman R, Ko P, Skolasky R, et al. 108. A new low profile sacro-pelvic fixation technique using S2 alar iliac (S2AI) screws in adult deformity fusion to the sacrum: a prospective study with minimum 2-year follow-up. Spine J. 2009;9(10):56–7.

    Article  Google Scholar 

  54. Sorour I, Elbary MA, Rabie A, Elhabashy AM. An early experience of lumbopelvic fixation techniques at Alexandria University. Egypt J Neurosurg. 2021;36(1):1–8.

    Article  Google Scholar 

  55. Yilmaz E, Abdul-Jabbar A, Tawfik T, Iwanaga J, Schmidt CK, Chapman J, et al. S2 alar-iliac screw insertion: technical note with pictorial guide. World Neurosurg. 2018;113:e296-301.

    Article  Google Scholar 

  56. Elder BD, Ishida W, Lo SFL, Holmes C, Goodwin CR, Kosztowski TA, et al. Use of S2-alar-iliac screws associated with less complications than iliac screws in adult lumbosacropelvic fixation. Spine (Phila Pa 1976). 2017;42(3):E142–9.

    Article  Google Scholar 

  57. Shabtai L, Andras LM, Portman M, Harris LR, Choi PD, Tolo VT, et al. Sacral alar iliac (SAI) screws fail 75% less frequently than iliac screws in neuromuscular scoliosis. J Pediatr Orthop. 2017;37(8):e470–5.

    Article  Google Scholar 

  58. Ilyas H, Place H, Puryear A. A comparison of early clinical and radiographic complications of iliac screw fixation versus S2 alar iliac (S2AI) fixation in the adult and pediatric populations. J Spinal Disord Tech. 2015;28(4):E199-205.

    Article  Google Scholar 

  59. Keorochana G, Arirachakaran A, Setrkraising K, Kongtharvonskul J. Comparison of complications and revisions after sacral 2 alar iliac screw and iliac screw fixation for sacropelvic fixation in pediatric and adult populations: systematic review and meta-analysis. World Neurosurg. 2019;132:408–20.

    Article  Google Scholar 

  60. Sponseller PD, Zimmerman RM, Ko PS, Pull Ter Gunne AF, Mohamed AS, Chang TL, et al. Low profile pelvic fixation with the sacral alar iliac technique in the pediatric population improves results at two-year minimum follow-up. Spine (Phila Pa 1976). 2010;35(20):187–92.

    Article  Google Scholar 

  61. De la Garza RR, Nakhla J, Sciubba DM, Yassari R. Iliac screw versus S2 alar-iliac screw fixation in adults: a meta-analysis. J Neurosurg Spine. 2019;30(2):253–8.

    Article  Google Scholar 

  62. Hasan MY, Liu G, Wong HK, Tan JH. Postoperative complications of S2AI versus iliac screw in spinopelvic fixation: a meta-analysis and recent trends review. Spine J. 2020;20(6):964–72.

    Article  Google Scholar 

  63. Mazur MD, Ravindra VM, Schmidt MH, Brodke DS, Lawrence BD, Riva-Cambrin J, et al. Unplanned reoperation after lumbopelvic fixation with S-2 alar-iliac screws or iliac bolts. J Neurosurg Spine. 2015;23(1):67–76.

    Article  Google Scholar 

  64. Desrochers-Perrault F, Aubin CE, Wang X, Schwend RM. Biomechanical analysis of iliac screw fixation in spinal deformity instrumentation. Clin Biomech. 2014;29(6):614–21.

    Article  Google Scholar 

  65. Lee MC, Jarvis C, Solomito MJ, Thomson JD. Comparison of S2-alar and traditional iliac screw pelvic fixation for pediatric neuromuscular deformity. Spine J. 2018;18(4):648–54.

    Article  Google Scholar 

  66. Hoernschemeyer DG, Pashuck TD, Pfeiffer FM. Analysis of the s2 alar-iliac screw as compared with the traditional iliac screw: Does it increase stability with sacroiliac fixation of the spine? Spine J. 2017;17(6):875–9.

    Article  Google Scholar 

  67. Wang Z, Boubez G, Shedid D, Yuh SJ, Sebaaly A. Is S1 alar iliac screw a feasible option for lumbosacral fixation? A technical note. Asian Spine J. 2018;12(4):749.

    Article  Google Scholar 

  68. Mattei TA, Fassett DR. Combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability technical note. J Neurosurg Spine. 2013;19(3):321–30.

    Article  Google Scholar 

  69. Mattei TA. S3 sacral-alar iliac screw: a salvage technique for pelvic fixation in complex deformity surgery. World Neurosurg. 2020;1(139):23–30.

    Article  Google Scholar 

  70. Ray WZ, Ravindra VM, Schmidt MH, Dailey AT. Stereotactic navigation with the O-arm for placement of S-2 alar iliac screws in pelvic lumbar fixation. J Neurosurg Spine. 2013;18(5):490–5.

    Article  Google Scholar 

  71. Bederman SS, Hahn P, Colin V, Kiester PD, Bhatia NN. Robotic guidance for S2-alar-iliac screws in spinal deformity correction. Clin Spine Surg. 2017;30(1):E49-53.

    Article  Google Scholar 

  72. Shillingford JN, Laratta JL, Park PJ, Lombardi JM, Tuchman A, Saifi C, et al. Human versus robot: a propensity-matched analysis of the accuracy of free hand versus robotic guidance for placement of S2 alar-iliac (S2AI) screws. Spine (Phila Pa 1976). 2018;43(21):E1297–304.

    Article  Google Scholar 

Download references


Not applicable.


Not applicable.

Author information

Authors and Affiliations



EY has conceptualized and designed the article, interpreted the relevant literature, drafted and revised the article critically for important intellectual content. The author has read and approved the final manuscript.

Corresponding author

Correspondence to Essam M. Youssef.

Ethics declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Youssef, E.M. Sacropelvic fixation. Egypt J Neurosurg 38, 2 (2023).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:


  • Sacropelvic
  • Fixation
  • Iliac
  • S2AI
  • Sacroiliac
  • Lumbosacral