Fluroscopy-assisted transiliac antegrade lag screw placement technique in both columns of acetabulum: A novel procedure

The use of pelvic osseous fixation corridors and lag screw fixation in acetabular and pelvic surgery has gained popularity, especially with the recent development of intraoperative imaging and navigation techniques. However, advanced intraoperative imaging and navigation techniques require technical equipment and are costly. Therefore, traditional fluoroscopic techniques still maintain their importance. In this article, we describe a novel pelvic osseous fixation corridor that traverses both columns of the acetabulum, along with the detailed methodology of its fluoroscopic imaging and the techniques for fluoroscopy-assisted screw placement. The technique of placing screws in this current fixation corridor is only under fluoroscopy assistance, without using any specially produced guide or navigation device. LEVEL OF PROOF: IV.

Bilateral dual iliac screw pelvic fixation for adult spinal deformity: a case report of a superior gluteal artery pseudoaneurysm secondary to aberrant iliac screw trajectory

PURPOSE

To present a case of a pseudoaneurysm of a branch of the left superior gluteal artery (SGA) secondary to lateral wall perforation from an iliac screw and its subsequent evaluation and management.

METHODS

Case report.

RESULTS

A 67-year-old female with a history of degenerative flatback and scoliosis and pathological fractures of T12 and L1 secondary to osteodisciitis underwent a single0stage L5-S1 ALIF and T9-pelvis posterior instrumented fusion with bilateral dual iliac screw fixation, revision T11-S1 decompression, and T12 and L1 irrigation and debridement and partial corpectomies. During the operation, non-pulsatile bleeding was encountered after creating an initial trajectory for the more proximal of the two left iliac screws. While the initial post-operative course was benign, the patient was readmitted for hypotension and anemia. Computed tomography of the abdomen/pelvis demonstrated a pseudoaneurysm (2.3 cm × 2.1 cm × 2.3 cm) of a branch of the left SGA. Diagnostic angiogram confirmed a pseudoaneurysm off of one of the branches of the left SGA. Endovascular embolization using multiple coils resulted in a complete cessation of blood flow in the pseudoaneurysm. At 2 years follow-up, no symptoms suggestive of recurrence of the pseudoaneurysm were reported.

CONCLUSIONS

A pseudoaneurysm of a branch of the left superior gluteal artery as a result of lateral wall perforation from an aberrantly placed iliac screw during an adult spinal deformity operation involving dual screw pelvic fixation is reported. Prompt recognition, multidisciplinary collaboration, and appropriate intervention were key in achieving a successful outcome and preventing further morbidity.

L4 fixation is not necessary in L5-Iliac spinopelvic fixation after trauma, but coadjutant transilio-transsacral fixation is

INTRODUCTION

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS AND CONCLUSIONS

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

Kyphectomy in myelomeningocele revisited: risk factors for failure

PURPOSE

Lumbar kyphosis occurs in approximately 8-20% of patients with myelomeningocele (MMC). The purpose of this article is to analyze the risks and benefits of vertebrectomy and spinal stabilization in MMC children with severe lumbar kyphosis and to establish treatment guidelines.

METHODS

This is an IRB-approved retrospective analysis of 59 patients with MMC who underwent kyphectomy and posterior instrumentation in three centers. Average age at surgery was 7.9 years (2 weeks-17 years). Sitting trunk position, skin status, kyphosis angle, and thoracic lordosis were analyzed preoperatively, postoperatively, and at an average follow-up of 8.2 years (range 2.5-16). The correction was maintained by applying a short posterior instrumentation in 6 patients, and extending to the pelvis in 53 cases. Pelvic fixation was achieved using the Warner and Fackler technique in 24 patients, the Dunn-McCarthy in 8, Luque-Galveston in 8, sacral screws in 2, and ilio-sacral screws in 11.

RESULTS

Sitting position improved postoperatively in 47 of the 53 patients who underwent pelvic fixation and only in one patient with short instrumentation. All 6 patients with long instrumentation and poor postoperative sitting balance were in the Dunn-McCarthy fixation group. Skin sores at the apex of the deformity disappeared postoperatively in all patients but recurred in two patients with short instrumentations. Kyphosis angle improved from 109° (45°-170°) preoperatively to 10° (0°-45°) postoperatively and 21° (0°-55°) at last follow-up. The best results were seen in cases where a cross-k-wire fixation of the kyphectomy site was used, augmented with a long thoraco-pelvic instrumentation consisting of Luque sublaminar wires in the thoracic region and a Warner-Fackler type of pelvic fixation. Good results were also found with the bipolar technique and ilio-sacral screw fixation. Six over 24 patients with the Warner and Fackler technique showed gradual dislodgment or hardware failure, with subsequent nonunion of the kyphectomy site in four. Infection, with or without wound dehiscence and/or hardware exposure, occurred in 17 cases, necessitating hardware removal in 9 patients.

CONCLUSION

Lumbar kyphosis in MMC children is best managed by resection of enough vertebrae from the apex to produce a flat lumbar spine, with perfect bone-to-bone contact and long thoraco-pelvic instrumentation using the Warner and Fackler technique through the S1 foramina or the bipolar technique with ilio-sacral screw fixation. Additional local fixation of the osteotomy site using cross-wires with or without cerclage increases the stability of the construct. The majority of complications occurred in patients with short instrumentations or where residual kyphosis persisted postoperatively regardless of the type of pelvic fixation or hardware density. The Dunn-McCarthy technique for pelvic fixation following kyphectomy in MMC was less successful in producing stable pelvic fixation and should not be considered in this patient category.

Activity and sports resumption after long segment fusions to the pelvis for adult spinal deformity: survey results of AO Spine members

PURPOSE

To assess recommendations for when adult spinal deformity (ASD) patients may return to athletic activities after surgery.

METHODS

A web-based survey was administered to members of AO Spine. The survey consisted of surgeon demographic information and questions asking when a patient undergoing a long thoracolumbar fusion (> 5 levels) with pelvic fixation for ASD would be allowed to resume unrestricted range of motion (ROM), non-contact sports, and contact sports postoperatively. Ordinal logistic regression was used to determine predictors for time to resume each activity.

RESULTS

One hundred twenty four members' responses were included for analysis. The majority of respondents would allow unrestricted ROM within 3 months postop (< 3 months: 81% vs > 3 months: 19%]. For when to return to non-contact sports, the most common responses were "2-3 months" (26.6%), "3-4 months" (26.6%), and "6-12 months" (18.5%). For when to return to contact sports, the majority advised > 4 months postop [> 4 months: "4-6 months" (19.2%), "6-12 months" (28.0%), " > 12 months" (28.8%) versus < 4 months: "1-2 months" (4.0%), "2-3 months" (1.6%), "3-4 months" (8.8%)]. 8.8% responded they would "never" allow resumption of contact sports.

CONCLUSION

There was significant variation between surgeons' recommendations for resumption of unrestricted range of motion and sports following long fusion with pelvic fixation for ASD. An evidence-based approach to activity recommendations will require information on outcomes and complications.

Complex surgical reconstruction for spinopelvic instability caused by a giant Tarlov cyst eroding the sacrum: A case report

Background

Tarlov cysts (TC), also known as perineural cysts are meningeal dilations of the posterior nerve root sheath that typically affect sacral nerve roots. TC are usually asymptomatic and found incidentally. We present the case of a patient with an enlarging sacral TC causing pain from spinopelvic instability secondary to extensive bone erosion. Such illustrative case is intended to increase awareness of the potential need for complex spinopelvic reconstruction in atypical instances of large TC.

Case Description

A 29-year-old female presented to clinic reporting progressive bilateral sacroiliac joint pain that was essentially mechanical in nature. The patient had a normal neurological exam except for a known left drop foot with numbness in the left sural nerve distribution, both attributed to a previously resected peripheral nerve sheath tumor. Magnetic resonance imaging revealed a large multilobulated lesion with imaging characteristics consistent with TC adjacent to the left side of the sacrum, extending outward from the left S1 and S2 neural foramina and measuring 6.7 × 3.7 cm in the axial plane and and 5.6 cm in the sagittal plane. Six weeks of conservative management consisting of physical therapy and pain management was unsuccessful, and the patient reported worsening pain. Surgical reconstruction consisting of L5-S1 transforaminal lumbar interbody fusion, L4 to pelvis navigation-guided instrumentation and posterolateral fusion, and bilateral sacroiliac joint fusion was successfully performed.

Outcomes

At 12 weeks follow-up appointment after surgery, the patient reported resolution of sacroiliac mechanical pain.

Conclusions

Sacral TC are asymptomatic in their vast majority of cases but may occasionally cause neurological deficits secondary to mass effect. Rarely, however, giant TC can also lead to significant bone erosion or the sacrum with secondary spinopelvic instability. In this brief report, we describe a giant TC generating significant spinopelvic instability, which was successfully treated with complex spinopelvic reconstruction, leading to complete resolution of the reported axial mechanical pain.

Distal junctional failure after corrective surgery without pelvic fixation for thoracolumbar junctional kyphosis due to osteoporotic vertebral fracture

BACKGROUND

Thoracolumbar junctional kyphosis (TLJK) due to osteoporotic vertebral fracture (OVF) negatively impacts patients' quality of life. The necessity of pelvic fixation in corrective surgery for TLJK due to OVF remains controversial. This study aimed to: 1) evaluate the surgical outcomes of major corrective surgery for thoracolumbar junctional kyphosis due to osteoporotic vertebral fracture, and 2) identify the risk factors for distal junctional failure to identify potential candidates for pelvic fixation.

METHODS

Patients who underwent surgical correction (fixed TLJK>40°, OVF located at T11-L2, the lowermost instrumented vertebra at or above L5) were included. Sagittal vertical axis, pelvic tilt, pelvic incidence, thoracic kyphosis, lumbar lordosis (L1-S1), local kyphosis, and lower lumbar lordosis (L4-S1) were assessed. Proximal and distal junctional kyphosis (P/DJK) and failures (P/DJF) were evaluated. Pre/postoperative spinopelvic parameters were compared between DJF and non-DJF patients.

RESULTS

Thirty-one patients (mean age: 72.3 ± 7.9 years) were included. PJK was observed in five patients (16.1%), while DJK in 11 (35.5%). Twelve cases (38.7%) were categorized as failure. Among the patients with PJK, there was only one patient (20%) categorized as PJF and required an additional surgery. Contrary, all of eleven patients with DJK were categorized as DJF, among whom six (54.5%) required additional surgery for pelvic fixation. In comparisons between DJF and non-DJF patients, there was no significant difference in pre/postoperative LK (pre/post, p = 0.725, p = 0.950). However, statistically significant differences were observed in the following preoperative alignment parameters: SVA (p = 0.014), LL (p = 0.001), LLL (p = 0.006), PT (p = 0.003), and PI-LL (p < 0.001).

CONCLUSIONS

Spinopelvic parameters, which represent the compensatory function of lumbar hyperlordosis and pelvic retroversion, have notable impacts on surgical outcomes in correction surgery for TLJK due to OVF. Surgeons should consider each patient's compensatory function when choosing a surgical approach.

O-Arm Accuracy and Radiation Exposure in Adult Deformity Surgery

OBJECTIVE

In long thoracolumbar deformity surgery, accurate screw positioning is critical for spinal stability. We assessed pedicle and pelvic screw accuracy and radiation exposure in patients undergoing long thoracolumbar deformity fusion surgery (≥4 levels) involving 3-dimensional fluoroscopy (O-Arm/Stealth) navigation.

METHODS

In this retrospective single-center cohort study, all patients aged >18 years who underwent fusion in 2016-2018 were reviewed. O-Arm images were assessed for screw accuracy. Effective radiation doses were calculated. The primary outcome was pedicle screw accuracy (Heary grade). Secondary outcomes were pelvic fixation screw accuracy, radiation exposure, and screw-related perioperative and postoperative complications or revision surgery within 3 years.

RESULTS

Of 1477 pedicle screws placed in 91 patients (mean 16.41 ± 5.6 screws/patient), 1208 pedicle screws (81.8%) could be evaluated by 3-dimensional imaging after placement. Heary Grade I placement was achieved in 1150 screws (95.2%), Grade II in 47 (3.9%), Grade III in 10 (0.82%), Grade IV in 1 (0.08%), and Grade V in 0; Grade III-V were replaced intraoperatively. One of 60 (1.6%) sacroiliac screws placed showed medial cortical breach and was replaced. The average O-Arm-related effective dose was 29.54 ± 14.29 mSv and effective dose/spin was 8.25 ± 2.65 mSv. No postoperative neurological worsening, vascular injuries, or revision surgeries for screw misplacement were recorded.

CONCLUSIONS

With effective radiation doses similar to those in interventional neuroendovascular procedures, the use of O-Arm in multilevel complex deformity surgery resulted in high screw accuracy, no need for surgical revision because of screw malposition, less additional imaging, and no radiation exposure for the surgical team.

Rescue Pelvic Fixation in a Patient with Sacral-2-Alar-Iliac and Triangular Sacroiliac Joint Fusion (Bedrock) Instrumentation

The purpose of this report is to demonstrate the creation of a 4-rod lumbosacral construct, when "stacked" sacral-2-alar-iliac (S2AI) screws are not possible due to a concurrent treatment of sacroiliitis with a posterior approach sacroiliac joint fusion device. This technique uses a combined S2AI and subcrestal iliac approach to achieve the 4-rod lumbosacral construct, while simultaneously biomechanically supporting the S2AI screws and treating the sacroiliitis.

Fragility Fractures of the Pelvis: Current Practices and Future Directions

PURPOSE OF REVIEW

To summarise the current evidence and clinical practices for patients with fragility fractures of the pelvis (FFP).

RECENT FINDINGS

FFPs are an increasingly prevalent and recognised problem in the elderly population. Recent evidence indicates they have a significant impact on function, morbidity and mortality. While traditional management of FFPs was predominantly non-surgical, surgical options have been increasingly used, with a range of surgical methods available. To date, limited consensus exists on the optimal strategy for suitable patient selection, and clinical trials in this population have proved problematic. The management of FFPs requires a multi-faceted approach to enhance patient care, including adequate pain control, minimisation of complications and optimisation of medical management. Early return to mobilisation should be a key treatment goal to maintain functional independence. The selection of patients who will maximally benefit from surgical treatment, and the most appropriate surgical strategy to employ, remains contentious.

Effect of pelvic fixation on ambulation in children with neuromuscular scoliosis

BACKGROUND

The effect of posterior spinal fusion (PSF) incorporating the pelvis on an ambulatory patient’s ability to mobilize after the fusion is not well understood.

AIM

To see whether a posterior spinal fusion with pelvic fixation using iliac or sacral alar iliac screws in ambulatory neuromuscular scoliosis (NMS) patients influences postoperative ambulatory ability.

METHODS

A retrospective review of all patients with NMS that underwent PSF with fixation incorporating the pelvis between January 1, 2012 and February 29, 2019. A total of 118 patients were eligible, including 11 ambulatory patients. The primary outcome was the maintenance of ambulatory status postoperatively. Secondary outcomes included postoperative curve magnitude, pelvic obliquity, and complications, comprising infections, instrumentation failure, and any unplanned returns to the operative room.

RESULTS

The ambulatory function was maintained in all 11 ambulatory NMS patients. One patient had an improvement in functional status with equipment-free ambulation postoperatively. An average postoperative follow-up was 19 mo. The overall complication rate was 19.4% (n = 23) with no significant differences between the groups in infection (P = 0.365), hardware failure (P = 0.505), and reoperation rate (P = 1.0). Ambulatory status did not affect complication rate (P = 0.967).

CONCLUSION

Spinal fusion to the pelvis in ambulatory patients with NMS provides effective deformity correction without the reduction in ambulatory capabilities.

Pelvic fixation is not always necessary in children with cerebral palsy scoliosis treated with growth-friendly instrumentation

PURPOSE

A previous study showed that patients with neuromuscular scoliosis who underwent fusion to L5 had excellent coronal curve correction and improvement in pelvic obliquity (PO) when preoperative L5 tilt was < 15°. Our purpose was to identify indications to exclude the pelvis in children with cerebral palsy (CP) scoliosis treated with growing-friendly instrumentation.

METHODS

In a retrospective cohort study, children with CP scoliosis treated with TGR, MCGR, or VEPTR with minimum 2-year follow-up were identified from a multicenter database.

RESULTS

27 patients with distal spine anchors (DSA) and 71 patients with distal pelvic anchors (DPA) placed at the index surgery were analyzed. The DSA group had a lower pre-index PO (9° vs 16°, P = 0.0001). Most recent radiographic data were similar except the DSA patients had a smaller major curve (47° vs 58°, P = 0.038). 6 (22%) DSA patients underwent extension of the instrumentation to the pelvis (DSA-EXT), most commonly at final fusion (5 patients). DSA-EXT patients had a higher pre-index L5 tilt than patients who did not require extension (DSA-NO EXT) (19° vs 10°, P = 0.009). Sub-analysis showed a lower major curve at most recent follow-up in the DSA-EXT group compared to the DPA group (33° vs 58°, P = 0.021). The DSA-EXT group had a higher number of complications per patient compared to the DSA-NO EXT group (2.3 vs 1.1, P = 0.029).

CONCLUSION

Pre-index L5 tilt ≤ 10° and PO < 10° may be indications to exclude the pelvis in children with CP scoliosis treated with growth-friendly instrumentation. DSA may provide better long-term control of the major curve than DPA.

The Utilization of Dual Second Sacral Alar-Iliac Screws for Spinopelvic Fixation in Patients with Severe Kyphoscoliosis

OBJECTIVES

As a new pelvic fixation technique, the dual S2AI screws fixation technique could provide highly stable distal strength, and have wide clinical prospect in the correction of severe kyphoscoliosis. However, the ideal trajectory parameters, indications and clinical outcomes of this technique have not been reported so far. This study aimed to determine the anatomical parameters of dual S2AI screws in the normal Chinese adult population, investigating the indications of this technique and evaluating the feasibility and clinical outcomes.

METHODS

Fifteen males and 15 females with normal pelvis underwent a pelvic CT scan to determine ideal dual S2AI screws trajectories. Sagittal angle (SA), transverse angle (TA), maximal length (ML), sacral length, and skin distance were measured. Subsequently, we retrospectively reviewed the data of 16 patients (seven males and nine females) who underwent dual S2AI screw fixation and 23 patients who underwent single S2AI screw fixation between January 2014 and December 2019. Preoperative, postoperative, and latest follow-up measurements of Cobb angle, coronal balance (CB), spinal pelvic obliquity (SPO), and regional kyphosis (RK) were obtained. The mean follow-up time was 16.7 ± 7.1 months (range: 12-30 months). Independent t-test was used to determine the difference in the analysis of the trajectories. The paired sample non-parametric Wilcoxon test was performed to assess the changes in radiographic parameters between different time points and different groups.

RESULTS

For both male and females, the proximal S2AI screws had significantly higher TA and ML, but a lower SA than distal screws. Females showed significantly more caudal (SA: 25.03° ± 2.32° vs. 29.82° ± 2.47°, t = 7.742, P < 0.001) trajectories of distal screw. Additionally, ML in the females were significantly shorter than that in males (106.81 mm ± 6.79 mm vs. 101.63 mm ± 6.55 mm, t = 3.007, P = 0.003, 124.41 mm ± 7.57 mm vs. 116.23 mm ± 7.03 mm, t = 4.337, P < 0.001). Eight had unilateral and eight had bilateral dual S2AI screw placement. Respectively, both the single S2AI and dual S2AI groups showed significant postoperative improvement of Cobb angle, RK angle and SPO angle. In patients with dual S2AI screws fixation, two patients found that screws loosening occurred in one of dual screws at 1-year follow-up, and in patients with single S2AI screws fixation, six patients found screw loosing as well as two patients found screw breakage at 1-year follow-up. None of all patients had any prominent loss of correction.

CONCLUSION

The ideal trajectory of dual S2AI screw could be well established. The dual S2AI screw fixation technique is feasible in patients with severe kyphoscoliosis, and provides satisfactory correction of deformity with few postoperative complications.

Is unrestricted weight bearing immediately after fixation of rotationally unstable pelvic fractures safe?

INTRODUCTION

Rotationally unstable pelvic fractures treated with surgical fixation have traditionally been treated with restricted weight bearing on the affected side for 6-8 weeks post operatively. We have been developing pelvic fixation standards to allow for unrestricted weight bearing immediately post operatively in type B rotationally unstable pelvic fractures.

AIMS

To assess for safety and efficacy of allowing unrestrictive weight bearing in this cohort of patients, we have clinically and radiologically monitored outcomes up to two years post operatively.

METHODS

Through retrospective review, two cohorts of patients with Tile Type B pelvic fractures were identified that were treated at the Royal Adelaide Hospital, South Australia. Patient demographics, injury classification, surgical fixation and weight bearing status post operatively was recorded. One cohort of patients was allowed to fully weight bear post operatively, whilst the other was treated with 6 weeks of restricted post op weight bearing. At clinical follow up, post-operative x-rays were assessed for loss of reduction, screw or plate breakage and reoperation.

RESULTS

Between January 2018 and January 2021, 53 patients with rotationally unstable pelvic fractures that underwent surgical fixation were included in this study. One group of patents were allowed to immediately weight bear as tolerated (WBAT) post operatively (n = 28) and the other with restricted weightbearing (RWB) (n = 25). There was 1 re operation for failure of fixation in each group. Metalwork breakage was more common in the WBAT group than in the RWB group and this was seen only in APC fractures. This increase in metalwork failure was not associated with loss of reduction.

CONCLUSIONS

With surgical fixation, Tile type B rotationally unstable pelvic fractures can be allowed immediate weight bearing post operatively. We found this to be safe and effective, employing surgical strategies to address both anterior and posterior injuries to allow immediate unrestricted weight bearing. Broken metalwork was more commonly seen in the WBAT group but this was not associated with loss of reduction or reoperation.

Ball Tip Technique for S2AI Screw Placement in Sacropelvic Fixation: A Comparative Study with Conventional Freehand Technique

Objective

To evaluate the efficiency of the ball tip technique for S2AI screw placement and introduce this technique.

Methods

Sixty‐three patients who underwent pelvic fixation with S2AI screws were retrospectively reviewed. They were 29 males and 34 females with an average age of 59.6 ± 12.5 years. Among these patients, 35 patients (14 males and 21 females with an average age of 58.8 ± 11.3 years) received ball tip technique and 28 patients (15 males and 13 females with an average age of 63.7 ± 12.6 years) received conventional freehand technique. Ball tip technique was used in ball tip technique group. After a pedicle probe just penetrated the sacroiliac joint, a ball‐tipped probe consisting of a ball shaped metal tip with a flexible shaft was malleted to make a guide track within ilium. This ball‐tipped probe could bend automatically away from the cortex and forward through the cancellous bone when the tip met the cortical lamina of ilium, which can avoid penetration. After repeating the procedures, a guide hole was gradually formed. S2AI screw was inserted along the guide hole after tapping. In the conventional freehand group, S2AI screw was placed according to the conventional method. Postoperative computed tomography (CT) was used to assess the accuracy of screws. The time cost of screw insertion and screw‐related complications were recorded. Independent t‐test was used to compare the time cost between ball tip group and conventional freehand group. A chi‐square test was used to compare the accuracies of the ball tip group with the conventional group.

Results

There were 35 patients (70 S2AI screws) in ball tip group and 28 patients (56 S2AI screws) in conventional freehand group. No screw‐related complication occurred in all patients. Time costs were 9.8 ± 4.5 mins in ball tip group and 20.2.0 + 8.6 mins in conventional freehand group, respectively (P < 0.05). Four screws penetrated iliac cortex in the ball tip group vs 10 screws in conventional freehand group (5.7% vs 17.9%) (P < 0.05).

Conclusions

The ball tip technique enhances the accuracy of screw placement and has less time cost compared with conventional freehand technique.

The posterior superior iliac rim screw as an adjunct to pelvic fixation in complex spinopelvic stabilization

BACKGROUND

Fixation to the ilium is a commonly used alternative or supplement to sacral fixation in complex spinopelvic reconstructions. This can be achieved with traditional posterior superior iliac spine or S2 alar-iliac screws. Posterior superior iliac rim screws may be considered to achieve or enhance pelvic fixation. The objective of this case series was to describe the use of and indications for posterior superior iliac rim screws.

METHODS

A retrospective review was performed of the medical records and radiographic data for three patients who underwent complex lumbosacral reconstructions involving the use of posterior superior iliac rim screws to enhance pelvic fixation. The cases included a 35-year-old with bilateral sacral fractures, a 43-year-old with extensive metastatic sarcoma to the sacrum, and a 48-year-old with multiple lumbar and pelvic fractures. An overview of the key surgical techniques is provided.

RESULTS

All three patients tolerated the procedure, without any unexpected post-operative complications or deficits. Radiographs at last follow-up showed stable fixation and no hardware issues.

CONCLUSIONS

The use of posterior superior iliac rim screws as an adjunct method of fixation in complex spinopelvic reconstructions is a feasible option that can be considered in the fixation armamentarium.

Pelvic Fixation Using S2AI and Triangular Titanium Implants (Bedrock Technique)

Pelvic fixation is becoming an increasingly important caudal anchor point for long lumbar constructs, high-grade spondylolisthesis, fixation of sacral fractures, and support for 3-column osteotomies, by adding lumbosacral fixation anterior to the McCord pivot point. Iliac bolts were once common but have become less favorable due to screw head irritation and complications associated with connecting rods. S2-alar-iliac (S2AI) screws have been shown to achieve equivalent anchoring strength of constructs to the pelvis, while being lower profile and in line with the lumbar instrumentation. More recently, surgeons have noted the potential for S2AI screws to toggle and loosen, commonly in the softer sacrum, leading to caudal anchor failure and possible pseudarthrosis. The addition of triangular titanium implants to augment S2AI screws (bedrock technique) is a relatively new adaptation to reduce toggling on the S2AI screw and improve the overall stability of the pelvic fixation. Video 1 shows the placement of an S2AI screw and triangular titanium implant for pelvic fixation. The patient is a 68-year-old woman who presented with flat back syndrome, spinal stenosis, degenerative spondylolisthesis, pseudarthrosis of previously instrumented levels, and bilateral sacroiliitis. She underwent posterior instrumentation and fusion of L1 to S1 with pelvic fixation, open bilateral sacroiliac joint fusion, and multilevel Smith-Peterson osteotomies and transforaminal lumbar interbody fusions.

Ilio-sacral screw pelvic fixation when correcting spinal deformities with or without pelvic obliquity: our experience over 40 years

Ilio-sacral screw fixation for treatment of spinal deformities with pelvic obliquity was used from more than 40 years in our department of pediatric orthopedics. Despite trying all the other systems published in the literature, the authors came back to iliosacral screw to address the pelvic fixation. Keeping the same anatomical and biomechanical principles, with no damage of the SI joint, they improve the technology over time, to allow an easy use. The fear about the precise insertion necessary to prevent any root irritation is now greatly reduced thanks to the modern navigation. The history of the establishment and the advantages of this technique are explained based on more than 250 cumulative cases with an excellent correction of the pelvic obliquity, without any case of complete pull out of the ilio-sacral screw. A very low rate of nonunion thanks to the 3D adaptation of the balance in erect standing or sitting posture of the patient, thanks to the motion of the intact SI joint, and the small sagittal motion existing in the linkage screw/connector. All this comparing favorably to the other techniques published in the current literature.

Intraoperative traction in neuromuscular scoliosis surgery improves major curve correction when fusing to L5

BACKGROUND

Intraoperative traction has shown improved curve correction in neuromuscular scoliosis surgery. It is found to be superior to anterior release in terms of correction of both main curve and pelvic obliquity. No previous study has examined the effect of intraoperative traction in patients without pelvic fixation.

METHOD

This retrospective study included 40 non-ambulatory (GMFCS 4 or above) patients with neuromuscular scoliosis undergoing surgery with bilateral segmental pedicle screw instrumentation to L5. Twenty-two consecutive patients had intraoperative Gardner-Wells tongs and skin traction (traction group), while the remaining did not (non-traction group). Inclusion criteria were minimum 2-year follow-up, complete medical records and radiographs. Main curve (MC), pelvic obliquity (POB), T1 tilt, kyphosis, rotation, coronal and sagittal balance and preoperative bending radiographs were measured and analyzed in all patients.

RESULTS

Both groups demonstrated roughly 60% MC correction. Preoperative MC was larger in the traction group [97° (49-126) vs. 83° (40-134); P = 0.03]. The measured correction index was almost twice as large in the traction group (1.9 vs. 1.1; P = 0.001). Mean [IQR] 2-year POB was 14° [7-40] in the traction group compared to 16° [4-60] in the non-traction group (P = 0.59). Eleven patients (50%) in the traction group compared to only four (22%) in the non-traction group had a POB within 10° at 2-year follow up (RR: 2.1; 95% CI 0.8-5.2). We found no difference in kyphosis or remaining radiographic parameters. No traction-related complications were recorded.

CONCLUSION

In patients with neuromuscular scoliosis undergoing instrumented fusion to the L5, we found that intraoperative traction increased the degree of MC correction and patients were more likely to achieve POB below 10° without any effects on sagittal parameters or without any detectable significant reduction on rotation.

Ambulatory capacity following fusion to the sacrum with pelvic fixations pediatric spinal deformity patients

OBJECTIVE

To investigate outcomes of ambulatory pediatric patients fused to the sacrum with pelvic fixation.

STUDY DESIGN

Retrospective cohort.

BACKGROUND

Historically in the pediatric spinal deformity literature, long fusions to the sacrum with pelvic fixation have been limited to non-ambulatory patients with pelvic obliquity. This analysis assesses the impact of how long fusions that include pelvic fixation in ambulatory pediatric patients.

METHODS

Consecutive pediatric patients undergoing fusion to the sacrum with pelvic fixation with any ambulatory capacity at a tertiary academic pediatric spine program from 2016 to 2018 were included in this review. Patient demographics, surgical details, and postoperative results were collected and analyzed to identify the impact on postoperative gait and ambulation function. Outcomes were determined from PROMIS, Parent Proxy Mobility questionnaires, as well as an institution specific pediatric gait questionnaire.

RESULTS

25 patients met inclusion criteria. 96.0% of patients had non-idiopathic scoliosis. 48% (12/25) of patients had previous spinal surgery. Median fusion levels were 17.0. 40% (10/25) had preoperative motor and gait deficits and only one patient with a documented decline at postoperative clinical examination. All 25 patients retained ambulatory capacity following their spinal fusion to the sacrum with pelvic fixation. 64% (16/25) of patients or family members completed the postoperative gait questionnaire. The mean PROMIS T-score was 43.4 (95% CI 36.5-50.0) for intact patients. The postoperative gait questionnaires revealed that 75% (6/8) of neurologically intact patients stated they would have the surgery again. 100% (8/8) of these patients noted an improved posture and 25% (2/8) reported a subjective decrease in ambulatory capacity status/post fusion to the sacrum. 100.0% (8/8) of limited ambulatory patients stated they would have the surgery again and noted improved posture with only 25% (2/8) noting a subjective decrease in ambulation postoperatively.

CONCLUSION

In appropriately selected pediatric spinal deformity patients fusion to the sacrum using pelvic fixation can maintain ambulation with high overall surgical satisfaction.

LEVEL OF EVIDENCE

III.

Limitations of posterior spinal fusion to L5 for flaccid neuromuscular scoliosis focusing on pelvic obliquity

STUDY DESIGN

Retrospective comparison based on the degree of pelvic obliquity (PO).

PURPOSE

To assess the controversial indications for and limitations of ending the instrumentation for posterior spinal fusion (PSF) at L5 in patients with flaccid neuromuscular scoliosis (fNMS).

METHODS

We reviewed the cases of 45 patients with progressive spinal deformity as a result of fNMS treated by PSF to L5 and followed for an average of 4 years postoperatively with adequate clinical and radiological data. Anterior-posterior and lateral whole spine radiographs were evaluated. We divided patients into two groups based on the degree of pelvic obliquity (PO) at the final follow-up. Radiographic data from the two groups were analyzed to identify the indications and limitations of this surgical method focusing on PO.

RESULTS

Preoperatively, there were significant differences between the two groups in Cobb angle, PO, thoracolumbar kyphosis, and lumbar lordosis (LL) while sitting; Cobb angle and LL while supine (Supine Cobb, and Supine LL); and major curve flexibility. Multivariate logistic regression analysis identified Supine Cobb and Supine LL as independent risk factors for residual PO at the final follow-up (Supine Cobb: odds ratio, 1.1; 95% confidence interval 1.0-1.2, Supine LL: odds ratio, 0.9; 95% confidence interval 0.8-1.0).

CONCLUSION

Patients with larger preoperative Cobb angle and smaller LL while supine may not achieve adequate spine and pelvic correction and this may lead to deterioration in the PO over time, even after spinal fusion ending at L5.

The use of triangular implants to enhance sacropelvic fixation: a finite element investigation

BACKGROUND CONTEXT

Long thoracolumbar fixation and fusion have become a consolidated treatment for severe spinal disorders. Concomitant sacropelvic fixation with S2 alar-iliac (S2AI) screws is frequently performed to limit instrumentation failure and pseudarthrosis at the lumbosacral junction.

PURPOSE

This study explored the use of triangular titanium implants in different configurations in which the implants supplemented standard sacropelvic fixation with S2AI screws in order to further increase the stability of S2AI fixation.

STUDY DESIGN

Finite element study.

METHODS

Four T10-pelvis instrumented models were built: pedicle screws and rods in T10-S1 (PED); pedicle screws and rods in T10-S1, and bilateral S2 alar-iliac screws (S2AI); pedicle screws and rods in T10-S1, bilateral S2AI screws, and triangular implants inserted bilaterally in a sacral alar-iliac trajectory (Tri-SAI); pedicle screws and rods in T10-S1, bilateral S2AI screws and two bilateral triangular titanium implants inserted in a lateral trajectory (Tri-Lat). The models were tested under pure moments of 7.5 Nm in flexion-extension, lateral bending and axial rotation.

RESULTS

SIJ motion was reduced by 50% to 66% after S2AI fixation; the addition of triangular titanium implants in either a SAI or a lateral trajectory further reduced it. S2AI, Tri-SAI, and Tri-Lat resulted in significantly lower stresses in S1 pedicle screws when compared to PED. Triangular implants had a protective effect on the maximal stresses in S2AI screws, especially when placed in the SAI trajectory. Sacropelvic fixation did not have any protective effect on the posterior rods.

CONCLUSIONS

Supplementing S2AI screws with triangular implants had a protective effect on the S2AI screws themselves, as well as the S1 pedicle screws, in the tested model.

CLINICAL SIGNIFICANCE

Triangular implants can substantially reduce the residual flexibility of the SIJ with respect to S2AI fixation alone, suggesting a possible role in patients needing reinforced fixation. In vivo investigation is needed to determine if these in vitro effects translate into clinically important differences.

S3 Sacral-Alar Iliac Screw: A Salvage Technique for Pelvic Fixation in Complex Deformity Surgery

Sacral-alar iliac (SAI) screws constitute a relatively new technique for pelvic fixation. Since their initial description in 2007, SAI screws have gained wide popularity among the spine surgery community. In 2013, we first described the possibility of using both S1 and S2 SAI screws for pelvic fixation in revision surgeries for adult degenerative scoliosis. Although a previous radiological study has suggested the feasibility of S3 and S4 SAI screws, to the best of our knowledge, there has been no report in the literature on the clinical use of such techniques. In this brief technical note, we present the first clinical report of the use of S3 SAI screws as a salvage method for pelvic fixation in a patient with suboptimal anatomy that prevented proper placement of S1 and S2 SAI screws. We also discuss the recommended anatomical entry points and trajectory of such screws.

Morphometric measurement and applicable feature analysis of sacral alar-iliac screw fixation using forward engineering

PURPOSE

To evaluate S1AI-S4AI screw channels with three-dimensional digital technology simulation analysis and to study the feasibility and applicable features of sacral alar-iliac screw fixation in adults.

MATERIALS AND METHODS

Forty (20 men and 20 women) normal adult's pelvic CT scan data sets were selected to reconstruct the three-dimensional pelvic model. The ideal S1AI-S4AI screw channels were simulated, followed by precise measurement of their parameters.

RESULTS

The results showed that there were no significant differences in the transverse angles, sagittal angles, radiuses of the maximal inscribed circles, or lengths of the screw channels in S1AI-S2AI screws between genders (P > 0.05). In contrast, the radiuses of the maximal inscribed circles on the left and right, respectively, were 5.93 ± 1.02 mm and 5.92 ± 1.04 mm in males and 4.64 ± 0.98 mm and 4.59 ± 0.95 mm in females, and there was a significant difference in S3AI screws between genders (P < 0.05). With a radius of 2.50 mm considered to be standard, there were 25 cases (62.5%) with an S4AI screw channel radius ≤ 2.50 mm in 40 adults, and 15 cases (37.5%; 9 males and 6 females) with a radius > 2.50 mm. Furthermore, the transverse angles, the sagittal angles, the lengths of the screw channels, and the radiuses of the maximal inscribed circles were significantly different between genders in 15 cases (P < 0.05).

CONCLUSION

Only one maximum ideal screw can be placed on one side at a time. With a radius of 2.50 mm considered to be standard, it is feasible to place S1AI-S3AI screws with a radius > 2.50 mm in the entire adult population and S4AI screws with a radius > 2.50 mm in some of the adult population. Furthermore, preoperative three-dimensional reconstruction and three-matic research software can effectively simulate the sacral alar-iliac screw channels, and they can provide accurate data for clinical applications.

Multiple-rod constructs in adult spinal deformity surgery for pelvic-fixated long instrumentations: an integral matched cohort analysis

PURPOSE

Multiple-rod constructs (Multi-Rod: extra rods for additional pillar support) are occasionally used in adult spinal deformity (ASD) surgery. We aimed to compare and analyze the general outcome of multi-rod constructs with a matched two-rod cohort, to better understand the differences and the similitudes.

METHODS

This is a retrospective matched cohort study including patients with ASD that underwent surgical correction with long posterior instrumentation (more than five levels), pelvic fixation and a minimum 1-year follow-up. Matching was considered with demographical data, preoperative radiographical parameters, preoperative clinical status [health-related quality-of-life (HRQoL) scores] and surgical characteristics (anterior fusion, decompression, rod material, osteotomies). Postoperative radiographical and clinical parameters, as well as complications, were obtained. Univariate and multivariate analysis was performed regarding postoperative improvement, group variables comparison and parameters correlation.

RESULTS

Thirty-three patients with multi-rod construct and 33 matched with a two-rod construct were selected from a database with 346 ASD-operated patients. Both groups had a significant improvement with surgical management in the radiographical and HRQoL parameters (p < 0.001). Differences between groups for the postoperative radiographical, clinical and perioperative parameters were not significant. Rod breakage was more frequent in the two-rod group (8 vs 4, p = 0.089), as well as the respective revision surgery for those cases (6 vs 1 p = 0.046). Risk factors related to revision surgery were greater kyphosis correction (p = 0.001), longer instrumentation (p = 0.037) and greater sagittal vertical axis correction (p = 0.049).

CONCLUSION

No major disadvantage on the use of multi-rod construct was identified. This supports the benefit of using multi-rod constructs to avoid implant failure. These slides can be retrieved under Electronic Supplementary Material.

Biomechanics of sacropelvic fixation: a comprehensive finite element comparison of three techniques

PURPOSE

Sacropelvic fixation is frequently used in combination with thoracolumbar instrumentation for complex deformity correction and is commonly associated with pseudoarthrosis, implant failure and loosening. This study compared pedicle screw fixation (PED) with three different sacropelvic fixation techniques, namely iliac screws (IL), S2 alar-iliac screws (S2AI) and laterally placed triangular titanium implants (SI), all in combination with lumbosacral instrumentation, accounting for implant micromotion.

METHODS

Existing finite element models of pelvis-L5 of three patients including lumbopelvic instrumentation were utilized. Moments of 7.5 Nm in the three directions combined with a 500 N compressive load were simulated. Measured metrics included flexibility, instrumentation stresses and bone-implant interface loads.

RESULTS

Fixation effectively reduced the sacroiliac flexibility. Compared to PED, IL and S2AI induced a reduction in peak stresses in the S1 pedicle screws. Rod stresses were mostly unaffected by S2AI and SI, but IL demonstrated a stress increase. In comparison with a previous work depicting full osteointegration, SI was found to have similar instrumentation stresses as those due to PED.

CONCLUSIONS

Fixation with triangular implants did not result in stress increase on the lumbosacral instrumentation, likely due to the lack of connection with the posterior rods. IL and S2AI had a mild protective effect on S1 pedicle screws in terms of stresses and bone-implant loads. IL resulted in an increase in the rod stresses. A comparison between this study and previous work incorporating full osteointegration demonstrates how these results may be applied clinically to better understand the effects of different treatments on patient outcomes. These slides can be retrieved under Electronic Supplementary Material.

Dual S2 Alar-Iliac Screw Technique With a Multirod Construct Across the Lumbosacral Junction: Obtaining Adequate Stability at the Lumbosacral Junction in Spinal Deformity Surgery

To illustrate the safe placement of a 5-screw/5-rod construct across the spinopelvic junction in a complex revision case utilizing 4 S2 alar-iliac (S2AI) screws as well as an iliac screw for a kickstand rod. The S2AI screws are often used for lumbosacral fixation at the base of long spinal deformity constructs. In severe spinal deformities, additional pelvic fixation beyond the standard 2 screws may help achieve and maintain correction, and also increase the rigidity of the construct. With a thorough understanding of pelvic anatomy, multiple pelvic screws, such as bilateral dual S2AI screws, may be placed safely to achieve stability and accommodate additional rods to perform powerful correction techniques. We illustrate the safe use of multiple rods across the lumbosacral junction in this case, by using both a hook rod construct and domino connectors – ultimately though these additional rods rely on the integrity of the pelvic fixation to provide their support. We recommend at least 3 rods across the lumbosacral junction in any adult spinal deformity case requiring pelvic fixation, and would recommend considering more than 3 rods, especially across 3-column osteotomy sites. For long spinal constructs in patients with significant adult spinal deformity, we believe the use of multiple pelvic screws to a multirod construct is a safe and effective way to provide long-term correction and clinical success.

Iliac screws may not be necessary in long-segment constructs with L5-S1 anterior lumbar interbody fusion: cadaveric study of stability and instrumentation strain

BACKGROUND CONTEXT

Lumbosacral pseudoarthrosis and instrumentation failure is common with long-segment constructs. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. The influence of iliac screws and interbody type on range of motion (ROM), rod strain (RS), sacral screw strain (SS) is not well-established.

PURPOSE

Investigate the effects of transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and iliac screws on long-segment lumbosacral construct biomechanics.

STUDY DESIGN

Biomechanical study.

PATIENT SAMPLE

Fourteen human cadaveric spine specimens.

OUTCOME MEASURES

Lumbosacral ROM, RS, and SS.

METHODS

Specimens were potted at L1 and the ilium. Specimens were equally divided into either an L5-S1 ALIF or TLIF group and underwent testing in the following conditions: (1) intact (2) L2-S1 pedicle screw rod fixation (PSR-S) (3) L2-ilium (PSR-I) (4) PSR-S+ALIF (ALIF-S) or TLIF (TLIF-S) (5) PSR-I + ALIF (ALIF-I) or TLIF (TLIF-I). Pure moment bending (7.5 Nm) in flexion, extension, lateral bending, axial rotation, and compressive loads (400N) were applied and ROM, SS, and RS were measured. Comparisons were performed using a one-way ANOVA (p<.05).

RESULTS

ALIF-S and TLIF-S provided similar decreases in ROM as TLIF-I (p>.05). Compared to PSR-S, PSR-I significantly decreased SS during bending in all directions (p<.02) but increased RS in flexion and extension (p≤.02). Anterior lumbar interbody fusion-S provided similar decreases in SS as TLIF-I in all directions (p>.40) but had significantly less RS than TLIF-I in flexion, extension, compression (p<.01). TLIF-S had more SS than TLIF-I in flexion, extension, axial rotation (p<.02), while TLIF-S had less RS only in flexion (p=.03). Compared to PSR-I, ALIF-I decreased the RS (p<.02) but TLIF-I did not (p>.67).

CONCLUSIONS

Iliac screws were protective of SS but increased RS at the lumbosacral junction. Constructs with ALIF and no iliac screws result in comparable SS as constructs with TLIF and iliac screws with significantly reduced RS. If iliac screws are utilized, ALIF but not TLIF reduces the iliac screw-induced RS.

CLINICAL SIGNIFICANCE

There is a relatively high incidence of lumbosacral instrumentation failure in adult spinal deformity. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. Iliac screws induce lumbosacral rod strain and may be responsible for instrumentation failure. Constructs with lumbosacral ALIF reduce iliac-screw induced rod strain and may obviate the need for fixation to the ilium.

Comparison of Sacral-Alar-Iliac and Iliac-Only Methods of Pelvic Fixation in Early-Onset Scoliosis at 5.8 Years' Mean Follow-up

STUDY DESIGN

Retrospective.

OBJECTIVE

Compare clinical outcomes in early-onset scoliosis (EOS) patients treated with sacral-alar-iliac (SAI) versus iliac-only methods of pelvic fixation at two years' minimum follow-up.

SUMMARY OF BACKGROUND DATA

Pelvic fixation in EOS is challenged by poor bone, anchor migration, and displacement. The long-term outcomes of SAI fixation in EOS is unknown.

METHODS

We retrospectively reviewed EOS patients in a single center from 2000 to 2017. Inclusion criteria were posterior spinal instrumentation with pelvic fixation before age 10 and 2 years' minimum follow-up. Clinical and radiographic data were analyzed using chi-squared and Student t tests (significance defined as p <.05).

RESULTS

Seven subjects were included in the iliac-only fixation group (Galveston technique = 2, iliac screws = 5) and 17 in the SAI group. For the iliac-only group (mean follow-up = 6.8 years), pelvic obliquity improved from a mean of 18° at initial presentation to 11° at first instrumentation (p = .096), to 9° at end follow-up (p = .060), whereas the major curve improved correspondingly from a mean of 84° to 50° (p = .002) to 39° (p = .006). For the SAI group (mean follow-up = 5.5 years) at the same time points, pelvic obliquity improved from a mean of 25° to 6° (p <.001) to 5° (p <.001), whereas the major curve improved from a mean of 83° to 38° (p <.001) to 29° (p <.001). SAI fixation was associated with fewer complications (11 complications in 17 patients) compared to iliac-only fixation (10 complications in 7 patients) (p = .04). Neither method was associated with pelvic growth disturbances or neurologic deficits.

CONCLUSIONS

In EOS patients at 2 years' minimum (5.8 years' mean) follow-up, both SAI and iliac-only methods corrected major curve, only SAI fixation corrected pelvic obliquity, and neither was associated with pelvic growth disturbances. SAI fixation was also associated with fewer complications. These findings may be due to the length and direction of the SAI anchors and abutment on the iliac cortex.

LEVEL OF EVIDENCE

Level III.

Anatomic Trajectory for Iliac Screw Placement in Pediatric Scoliosis and Spondylolisthesis: An Alternative to S2-Alar Iliac Portal

STUDY DESIGN

Single-center retrospective study.

OBJECTIVE

To analyze two-year postoperative outcomes following spinopelvic fixation in pediatric patients using the anatomic trajectory (AT) portal for iliac screws.

SUMMARY

Iliac fixation is crucial in situations requiring fusion to sacrum. Challenges include complex anatomy, pelvic deformation, severe deformity, and previous surgery. The PSIS portal requires significant dissection, rod connectors, and complex bends. The SAI portal requires navigating the screw across the SI joint to the ilium. The anatomic trajectory (AT), first reported in 2009, is between the PSIS and SAI portal, without prominence, connectors, or complex bends.

METHODS

Fifty-four patients aged ≤18 years requiring instrumentation to the Ilium with minimum follow-up of two years (mean 44 months) were clinically and radiographically evaluated. Changes in coronal curve magnitude and pelvic obliquity were assessed using paired t test for patients with cerebral palsy. Spondylolisthesis reduction was assessed in patients with moderate- to high-grade spondylolisthesis (Meyerding grade 3 and 4).

RESULTS

A total of 108 iliac screws were inserted using AT portal in 54 patients. Twenty-eight neuromuscular and syndromic patients had an initial mean coronal curve of 85° corrected to 23° at two years (p < .001) and a pelvic obliquity of 22° corrected to 4° (p < .001). Twenty patients with moderate- to high-grade spondylolisthesis treated with reduction and interbody fixation improved significantly with respect to their slip angles (7° ± 14.7° to -7.9° ± 6.1°, p = .003). In the neuromuscular group, two surgical site infections occurred, two had implant fractures, and 12 had asymptomatic iliac screw loosening, none requiring revision. In the spondylolisthesis group, there were no neurologic complications and one had prominent screw requiring removal. Of 108 iliac screws, 2 rod connectors were employed.

CONCLUSION

Iliac screw insertion using the AT portal is a safe and effective method of pelvic fixation in pediatric patients with satisfactory radiographic correction and minimal complications.

LEVEL OF EVIDENCE

Level 4.

Radiographic and Clinical Outcomes of Surgical Correction of Poliomyelitis-Related Spinal Deformities: A Comparison Among Three Types of Pelvic Instrumentations

BACKGROUND

We compared the clinical and radiographic outcomes of corrective surgery in patients with poliomyelitis-related spinal deformity (PSD) using 3 types of pelvic fixation and investigated the incidence and risk factors for complications.

METHODS

We reviewed the data from 42 patients with PSD who had undergone spinopelvic reconstruction at a single institution from 2000 to 2016. Of the 42 patients, 15 had been treated with the Galveston technique, 13 with iliac screw fixation, and 14 with S2-alar-iliac (S2AI) screw fixation. Demographic data, radiographic parameters, and complications were analyzed. Health-related quality of life was determined using Scoliosis Research Society (SRS) 22-item questionnaires and the Oswestry Disability Index scores.

RESULTS

After surgery, the correction rate of the main curve was 51.7%, 57.8%, and 52.1% in the 3 groups, with significant improvement in regional kyphosis, coronal balance, and pelvic obliquity (PO) (P < 0.05). The correction of PO was similar among the 3 types of pelvic fixation; however, the patients treated with S2AI fixation required significantly less operative time (P < 0.05) and blood loss (P < 0.006). The overall complication rate was 40.5%, with a major complication rate of 23.8%. Age at surgery (P = 0.006) and grade >2 SRS-Schwab osteotomy (P = 0.036) were significant risk factors for complications. Significant improvement was found in the SRS-22 and Oswestry Disability Index scores at the final follow-up examination in the 3 groups.

CONCLUSIONS

The present study showed satisfactory correction of spinopelvic deformity for 42 patients with PSD. Compared with the Galveston technique and iliac screw fixation, the use of S2AI significantly decrease the operative time and estimated blood loss and obtained similar correction of PO. Patient age at surgery and grade >2 SRS-Schwab osteotomy were significant risk factors for complications.

The comparison of the results after spinal fusion with or without iliac screw insertion in the treatment of neuromuscular scoliosis

Introduction

Neuromuscular scoliosis leads to a wide range of spinal disorders which disturb the musculoskeletal system. The aim of this study is to compare the clinical and radiological results of posterior spinal fusion with and without extending the instrumentation to iliac bones in treatment of neuromuscular scoliosis.

Methods

Medical records and radiographies of 36 patients with neuromuscular scoliosis who underwent posterior instrumentation between 2011 and 2015 were reviewed. Age and body mass index at time of surgery, underlying diagnosis, gender, postoperative infection rates, perioperative and postoperative blood transfusion, duration of surgery, complication rates were identified for each patient retrospectively. SF-36 physical questionnaire was applied to all patients. Surgery was performed in each patient and included posterior spinal fusion with pedicle screws from the proximal thoracic spine (T2 or T3) to S1 (Group A) or extension of distal instrumentation to pelvis by bilateral iliac screws (Group B).

Results

A total of 23 patients in group A were compared with 13 patients in group B. Median age was 14 (9–38) years for group A and 16 (12–25) years for group B. Median follow-up period was 20 (12–66) months. Preoperative median Cobb angles were 66^° and 60^° and postoperative Cobb values were 33^° and 31^° in group A and B respectively. Median Cobb angle reduction was 40^° and 34^° for group A and B. We are able to see in this study that the usage of illiac screws do not increase implant failure and help achieve better functional results.

Conclusion

This study shows that the extention of instrumentation to the pelvis with illiac screws can be beneficial in terms of functional and complicational incidences.

Level of evidence: Level III, therapeutic study.

Fixation to Pelvis in Pediatric Spine Deformity-An Analysis of 30-Day Outcomes

OBJECTIVE

To assess the impact of fixation to pelvis on 30-day outcomes after posterior spinal fusions in pediatric spine deformities.

METHODS

The 2012-2016 American College of Surgeons-National Surgical Quality Improvement Program pediatric database was queried using Current Procedural Terminology codes for patients undergoing posterior spinal fusions (22800, 22802, and 22804). Patients undergoing concurrent anterior fusion/combined fusion and anterior-only fusions were removed from the study. Patients undergoing additional fixation to pelvis were identified by code 22848.

RESULTS

Of a total of 13,398 patients, 1092 (8.2%) patients underwent a fixation to the pelvis. After adjustment for differences in baseline characteristics, patients undergoing fixation to pelvis had a longer length of stay (odds ratio [OR] 1.24; 95% confidence interval [CI] 1.04-1.48]), greater odds of any 30-day complication (OR 1.26; CI 1.03-1.55), pneumonia (OR 1.85; CI 1.26-2.70), renal insufficiency (OR 6.87; CI 2.02-23.40), acute renal failure (OR 14.23; CI 2.36-84.51), urinary tract infection (OR 1.99; CI 1.23-3.23), cardiac arrest (OR 2.98; CI 1.10-8.06), sepsis (OR 2.25; CI 1.35-3.74), bleeding (OR 1.51; CI 1.25-1.82), 30-day readmissions (OR 1.39; CI 1.07-1.81), and 30-day reoperations (OR 1.37; CI 1.06-1.76).

CONCLUSIONS

In contrast to adult spinal deformity literature, pediatric patients undergoing a fixation to pelvis are at a greater risk of experiencing adverse outcomes within 30 days of surgery. Providers should use these data for preoperative counseling and/or risk-stratification to improve quality-of-care in the acute postoperative period in these patients.

Risk Factors for Perioperative Blood Transfusions in Adult Spinal Deformity Surgery

OBJECTIVE

Adult spinal deformity (ASD) surgery is associated with a high rate of perioperative blood transfusions, and it is important to understand the risk factors for perioperative blood transfusions to implement strategies to reduce transfusions. The aim of this study was to identify independent risk factors of perioperative blood transfusions in patients undergoing surgery for ASD.

METHODS

A retrospective cohort study was performed using the American College of Surgeons National Surgical Quality Improvement Program database from 2010 to 2014. Adult patients undergoing surgery for ASD were separated into 2 cohorts based on whether they received a perioperative blood transfusion. Univariate and multivariate regression models were used to identify risk factors for blood transfusion.

RESULTS

In our cohort of 5805 patients, 27.1% received a blood transfusion. Multivariate regression analysis showed that patient-specific risk factors were age 65 years or older (odds ratio [OR], 1.74; 95% confidence interval [CI], 1.49-2.03; P < 0.001), American Society of Anesthesiologists classification of 3 or greater (OR, 1.18; 95% CI, 1.01-1.37; P = 0.033), cardiac comorbidity (OR, 1.21; 95% CI, 1.03-1.41; P = 0.018) and bleeding disorder (OR, 2.01; 95% CI, 1.10-3.66; P = 0.023). Surgery-specific risk factors were a posterior approach (OR, 4.25; 95% CI, 3.46-5.22; P < 0.001), pelvic fixation (OR, 1.73; 95% CI, 1.36-2.20; P < 0.001), and osteotomy (OR, 2.08; 95% CI, 1.71-2.51; P < 0.001). Longer operative time was also a risk factor with a duration-dependent effect on the odds of blood transfusion.

CONCLUSIONS

Recognition of patient- and surgery-specific risk factors for perioperative blood transfusion is important to identify patients who are at high risk and to implement strategies to minimize intraoperative blood loss and decrease healthcare costs.

Comparison of S2-Alar and traditional iliac screw pelvic fixation for pediatric neuromuscular deformity

BACKGROUND CONTEXT

Many pelvic fixation options exist for posterior spinal fusion of pediatric neuromuscular scoliosis, including standard iliac screws (SISs) or a more recently introduced S2-Alar (S2A) technique. However, little data exist comparing the clinical and radiographic outcomes of these techniques.

PURPOSE

This study aimed to dentify differences in clinical and radiographic outcomes for pediatric neuromuscular scoliosis patients treated with SIS or S2A pelvic fixation.

STUDY DESIGN/SETTING

This was a retrospective cohort study at a pediatric orthopedic clinic.

PATIENT SAMPLE

Patients aged 8-19 years undergoing posterior spinal fusion to the pelvis for neuromuscular scoliosis using SIS or S2A technique, with Gross Motor Function Classification System (GMFCS) Level 4 or 5 were included.

OUTCOMES MEASURES

Postoperative complication rates associated with pelvic fixation method were the outcome measures.

METHODS

Charts and radiographs were reviewed for demographics, intra- and postoperative course, levels of instrumentation, operative correction, and implant failure (IF). Postoperative complications were classified according to the Accordion scale.

RESULTS

We studied 50 patients (28 SIS, 22 S2A) aged 14.0±2.8 years and an average follow-up of 3.5±1.7 years. The average number of levels fused was 16.5±1.1 with an average curve correction of 48°±21° postoperatively. A significant difference in radiographic IF rates was noted between SIS and S2A groups (57% vs. 27%, p=.02). No difference was noted between groups for frequency or severity of postoperative complications, inclusive of wound infections. Subgroup analysis demonstrated equivalent IF rates when comparing the S2A group with the SIS group with cross-links.

CONCLUSIONS

The S2A group generally demonstrated improved rates of radiographic IF compared with the SIS group, but the rates became equivalent when a cross-link was added to an SIS construct. Further, no difference in postoperative complication rates were identified between SIS and S2A groups.

Proper detailed parameters for S1 sacral alar iliac screw placement in the Chinese population, a 3D imaging study

Background

S1-AI technique may be used as a salvage technique in pelvic fixation of complex spinal deformity surgery. However, the proper detailed parameters in the Chinese population has not been analyzed before to instruct S1-AI screws placement and to ensure the safety of clinical application while the trajectory in pelvic changes significantly at each angle.

Results

The ideal S1AI screw trajectory could be obtained in 28 of 30 female patient images (93.3%) and in all of the male patient images (100%). The screws that have already been used clinically in S2AI pathways can be applied in S1AI fixations.

Conclusion

It is feasible to place S1AI screws in 93.3% of female Chinese adult patients and in all male Chinese patients. Preoperative CT reconstruction should be performed to evaluate proper trajectory parameters and to avoid anterior violation.

S2 Alar Iliac Fixation in Long Segment Constructs, a Two- to Five-Year Follow-up

STUDY DESIGN

Retrospective review of patients having undergone S2 alar-iliac (S2AI) fixation for long fusions with a minimum two-year follow-up.

OBJECTIVES

To report on fusion rates, complications, technique-specific complications of patients having undergone S2AI fixation.

SUMMARY OF BACKGROUND DATA

Sacropelvic fixation continues to be a challenge when performing long fusions to the pelvis. S2AI screws have been found to provide solid biomechanical fixation and have been found to have good clinical results in short-term follow-up for pediatric and adult patients.

METHODS

Cases were retrospectively reviewed in patients who had placement of S2AI screws for long fusions with at least a two-year follow-up. Demographic data, complications, and reoperations were reviewed. Complications were broken into minor and major categories similar to previous series on pelvic fixation.

RESULTS

There were 86 cases identified. Minor and major complications occurred in 29% and 24% of patients, respectively, with the majority of minor complications being intraoperative dural tears. Revision surgery for all causes was performed in 23% of the cohort. Fusion rate at L5-S1 for patients without preoperative pseudarthrosis was 95.3%. Preoperative L5-S1 pseudoarthrosis was identified in 20 patients, 17 (95%) of these went onto fusion after one surgery. There was evidence of S2AI screw lucency in 10.4% of cases. However, the majority of these were asymptomatic.

CONCLUSIONS

Sacropelvic fixation using the S2AI technique provides safe, durable fixation with low rates of technique-specific complications and limited need for hardware removal. Complication rates in this series were similar to other series on long fusions to the pelvis. Additionally, fusion rates were high at L5-S1 for both patients with and without preoperative L5-S1 pseudarthrosis. It appears that the S2AI technique is a powerful option for patients with previous L5-S1 pseudarthrosis.

LEVEL OF EVIDENCE

Level III.

Sacral-Alar-Iliac Fixation in Children with Neuromuscular Scoliosis: Minimum 5-Year Follow-Up

OBJECTIVE

To investigate the 5-year outcomes of children with neuromuscular scoliosis treated with sacral-alar-iliac screws.

METHODS

We reviewed clinical and radiographic records of patients aged ≤18 years treated by 1 pediatric orthopedic surgeon for neuromuscular scoliosis with spinal fusion using sacral-alar-iliac pelvic anchors. Thirty-eight patients with a minimum 5-year radiographic follow-up (mean, 6.0 ± 1.2 years) were studied. The mean patient age was 13 ± 2.0 years, and 47% were female. The mean number of levels fused was 18 ± 0.7. Two-thirds (66%) of the patients were diagnosed with cerebral palsy.

RESULTS

Between the preoperative period and final follow-up, the patients exhibited a mean correction of the major coronal curve of 79% (preoperative, 85° to final, 18°) and a mean 57% correction of the pelvic obliquity (preoperative, 16° to final, 7°). Patients maintained the correction of mean pelvic obliquity from the early postoperative period (6°) to final follow-up (7°). Preoperatively, 76% of the patients had a pelvic obliquity of >10°, compared with 26% of patients postoperatively. There were no cases of neurologic or vascular complications or pseudarthrosis. Radiographs revealed bilateral sacral-alar-iliac screw lucency in 8 patients; 4 of these patients had deep wound infections, and the other 4 were asymptomatic. Unilateral screw fracture was found in 1 patient with an 8-mm-diameter screw (1.3%; 1 of 76 screws); the patient was observed and remained asymptomatic. There were no cases of set screw displacement, screw back-out, or rod dislodgement.

CONCLUSIONS

Sacral-alar-iliac screws are safe and effective pelvic anchors for use in children with neuromuscular scoliosis.

S2-AI screw placement with the aide of electronic conductivity device monitoring: a retrospective analysis

STUDY DESIGN

A retrospective analysis of two consecutive patients who underwent a novel surgical technique.

OBJECTIVE

A report of a novel surgical technique utilizing an electronic conductivity device guidance to aide placement of S2-Alar-Iliac (S2-AI) instrumentation. Electronic conductivity guidance for instrumentation of the thoracolumbar spine is an accepted means of improving intraoperative accuracy. Although commercially available for percutaneous techniques, there is a paucity of literature regarding its use. Percutaneous implantation of S2-AI screws has been previously described as another technique surgeons can avail, primarily employing fluoroscopy as a means of intraoperative feedback. We describe a novel technique that utilizes electronic conductivity as an added feedback measure to increase accuracy of percutaneous S2-AI fixation.

METHODS

Two patients were treated by the senior author (FAS) who underwent surgery employing S2-AI fixation utilizing an electronic conductivity device (Pediguard cannulated probe, Spineguard, Paris, France). The surgical technique, case illustrations, and radiographic outcomes are discussed.

RESULTS

Stable and accurate fixation was attained in both patients. There were no peri-operative complications related to hardware placement.

CONCLUSION

To the authors' knowledge, this is the first reported literature combining S2-AI screws with electronic conductivity for immediate intraoperative feedback. This technique has the opportunity to provide surgeons with increased accuracy for placement of S2-AI screws while improving overall radiation safety. This feedback can be particularly helpful when surgeons are learning new techniques such as placement of S2AI screws.

S2 Alar-iliac Fixation: A Powerful Procedure for the Treatment of Kyphoscoliosis

The purpose of this study was to introduce a powerful technique for the treatment of kyphoscoliosis. There are currently multiple techniques for sacropelvic fixation, including trans-iliac bars and iliac and iliosacral screws. Several studies have documented the use of these instrumentation techniques; however, a ubiquitous problematic issue concerns the need for separate incisions for the use of offset connectors, which add to surgical time and morbidity. Any additional dissection of the skin, subcutaneous tissue or muscle in this area is believed to increase the incidence of complications of wound healing. However, as stated above, the above-mentioned techniques require separate incisions for the use of offset connectors, which add to surgical time and morbidity. The novel technique of S2 alar-iliac (S2AI) pelvic fixation has been developed to address some of these issues. However, a technique for achieving correction of kyphoscoliosis with pelvic obliquity in adult patients with spinal deformity has not previously been described. Our entry point is based on the S1 foramen and is typically up to 5 mm caudal and 2 to 3 mm lateral to that foramen. Once the S1 foramen has been identified, a blunt instrument can be used to probe the alar ridge. The screw trajectory is 40°-50° from horizontal and 20°-30° caudal, aimed toward the greater trochanter and rostral to the sciatic notch. A 36-year-old female patient presented with a 3-year history of low back pain, and progressive thoracolumbar kyphoscoliosis. In this typical case, we performed S2AI fixation with transforaminal lumbar interbody fusion and hemivertebra resection technique to treat her lumbosacral kyphoscoliosis. Satisfactory improvement in her preoperative lumbar kyphoscoliosis was found at 3-month follow-up.

Sacral-Alar-Iliac Fixation in Pediatric Deformity: Radiographic Outcomes and Complications

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To assess the radiographic outcomes and complications of sacral-alar-iliac (SAI) fixation in children.

SUMMARY OF BACKGROUND DATA

Pelvic fixation in children undergoing spinal deformity surgery can be challenging because of complex anatomy, compound biomechanical forces at the lumbosacral junction, and poor bone quality.

METHODS

Radiographic and clinical records of 80 consecutive patients aged 18 years or younger who underwent posterior spinal fusion surgery with SAI fixation by one pediatric orthopedic surgeon and who had a minimum 2 years of follow-up (mean follow-up: 3.5 years, range, 2-7 years) were retrospectively reviewed. Changes in coronal curve magnitude and pelvic obliquity were assessed using Student t tests. Significance was set at a p value less than .05 for all analyses.

RESULTS

Pelvic obliquity correction averaged 77%, from 26 ± 13 degrees before surgery to 6 ± 4 degrees at final follow-up (p < .001); 91% of the patients were corrected to a pelvic obliquity of less than 10 degrees. Coronal curve correction averaged 72%, from 78 ± 27 degrees before surgery to 22 ± 15 degrees at final follow-up (p < .001). No patient had vascular or neurologic complications or died perioperatively. Twenty patients (25%) had radiographic evidence of implant-related problems, of which there were nine screw fractures (all in the neck of screws with ≤8-mm outer diameter). Six patients had symptomatic complications associated with SAI fixation (three patients with pseudarthrosis at the lumbosacral junction, all of whom required revision surgery, two patients with implant prominence, and one patient with pain related to implant). Other complications included seven instances of wound dehiscence, three deep wound infections, and one superficial wound infection.

CONCLUSIONS

SAI fixation provided a low-profile alternative to iliac screws for the correction of pelvic obliquity. The largest possible diameter screws are recommended, ideally >8 mm.

LEVEL OF EVIDENCE

Level 4.

Predicting Failure of Iliac Fixation in Neuromuscular Spine Deformity

STUDY DESIGN

Retrospective comparative cohort study.

OBJECTIVES

Identify whether there are patient or surgical risk factors to predict the probability of failure of iliac screw fixation after correction of neuromuscular scoliosis.

SUMMARY OF BACKGROUND DATA

There are high reported failure rates of pelvic fixation in long posterior spinal fusion (PSF) constructs to the sacrum for neuromuscular scoliosis.

METHODS

Patients aged 5 to 25 years, at a single institution, had PSF to the sacrum from 2001 to 2009 with pelvic fixation using iliac screws. Clinical data were retrospectively reviewed to identify patient and surgical variables related to surgery. Failure of iliac fixation was identified strictly as a broken screw, disengagement of the screw from the connector or the connector from the rod, or set plug failure. Lucency around the screws greater than 2 mm was recorded but not considered a failure. Variables were analyzed in a statistical model to identify predictors of failure.

RESULTS

A total of 108 patients met inclusion criteria; 100 (38 female and 62 male) had appropriate radiographs and minimum 2-year follow-up (average, 5.5 years). Coronal deformity correction averaged 59%. Most patients (89%) had fill of 6 of 8 possible distal fixation points composed of L4, L5, S1, and ilium bilaterally. Iliac screw failure occurred in 27 patients (27%). The initial single predictor statistical model identified 2 possible predictors of failure (patient: spastic tone; and surgical: absence of distal crosslink). In the multivariable model, spastic tone remained a predictor of failure (p = .0103), whereas absence of distal crosslink bordered on significance (p = .0516).

CONCLUSIONS

Iliac screw fixation failure is common in patients with long PSF constructs for neuromuscular scoliosis. Spastic tone is a risk factor for failure of pelvic fixation. A distal crosslink may protect against pelvic fixation failure. Alternative techniques for pelvic fixation should be studied in an attempt to improve the failure rates of iliac screw pelvic fixation.