Intrasacral rod fixation for pediatric long spinal fusion: results of a prospective study with a minimum 5-year follow-up

Three-Dimensional Analysis of the Ideal Entry Point for Sacral Alar Iliac Screws

STUDY DESIGN

This is a virtual three-dimensional (3D) imaging study examining computed tomography (CT) data to investigate instrumentation placement.

PURPOSE

In this study, we aim to clarify the ideal entry point and trajectory of the sacral alar iliac (SAI) screw in relationship to the dorsal foramen at S1 and the respective nerve root.

OVERVIEW OF LITERATURE

To the best of our knowledge, there is yet no detailed 3D imaging study on the ideal entry point of the SAI screw. Despite the evidence suggesting that the dorsal foramen at S1 is a landmark on the sacrum, the S1 nerve root disruption is a general concern during the insertion of SAI screws. No other study has been published examining the nerve root location at the S1and SAI screw insertions.

METHODS

Preoperative CT data from 26 patients pertaining to adult spinal deformities were investigated in this study. We applied a 3D image processing method for a detailed investigation. Virtual cylinders were used to mimic SAI screws. These were placed to penetrate the sacral iliac joint without violating the other cortex. We then assessed the trajectory of the longest SAI screw and the ideal entry point of SAI using a color mapping method on the surface of the sacrum. We measured the location of the nerve root at S1 in relation to the foramen at S1 and the sacral surface.

RESULTS

As per the results of our color mapping, it was determined that areas that received high scores are located medially and caudally to the dorsal foramen of S1. The mean angle between a horizontal line and a line connecting the medial edge of the foramen and nerve root at S1 was 93.5°. The mean distances from the dorsal medial edge of the foramen and sacral surface to S1 nerve root were 21.8 mm and 13.9 mm, respectively.

CONCLUSIONS

The ideal entry point of the SAI screw is located medially and caudally to the S1 dorsal foramen based on 3D digital mapping. It is also shown that this entry point spares the S1 nerve root from possible iatrogenic injuries.

Anatomical Study of a Novel Iliosacral Screw Placement for Sacrum-Pelvis in Adult Via Computed Tomography Reconstruction

STUDY DESIGN

This is a cross-sectional study.

OBJECTIVE

To investigate the feasibility and safety of a novel iliosacral screw placement for sacrum-pelvis in adult pelvis by computed tomography (CT) reconstruction.

SUMMARY OF BACKGROUND DATA

The optimal technique of spino-pelvic fixation is still being developed and redefined. However, neither the relevant anatomic parameters nor the potential spinal canal involvement for a novel iliosacral screw placement have been clearly analyzed.

METHODS

A total of 60 adults with normal pelvis, with the age ranging from 24 to 79 years old, were included in this study. Based on three-dimensional (3D) CT reconstruction of each pelvis, virtual iliosacral screw channel was identified bilaterally, the trajectory of which was characterized with the optimal width and length from the ilium to the sacrum. The virtual iliosacral screw channel that holding the greatest width and length of osseous channel was measured by rotating the 3D pelvis. Measurements of the determined channel on either side included iliosacral-screw-related and connector-related parameters.

RESULTS

There was a virtual iliosacral screw channel passing through the ilium, the iliosacral joint and then into the sacrum on either side of each pelvis. The caudal angle, convergent angle, and maximal length were 16.3 ± 3.0°, 61.3 ± 5.9°, 97.0 ± 5.6 mm in male, respectively. In female, they were 16.4 ± 3.9°, 63.0 ± 5.5° and 96.2 ± 6.0 mm, respectively. The ideal direction of the connector was from posteromedial to anterolateral. The cephalad angle, divergent angle, and embedding depth of the connector were 28.0 ± 5.7°, 28.7 ± 5.9° and 19.0 ± 2.9 mm in male, respectively. In female, they were 26.7 ± 6.1°, 27.0 ± 5.5° and 16.4 ± 2.6 mm, respectively.

CONCLUSION

It is safe and feasible to place the iliosacral screw when performing this novel instrumentation. Preoperative CT imaging and 3D reconstructions may help to determine the correct entry point and the trajectory of iliosacral screw.

LEVEL OF EVIDENCE

5.

Radiological and functional outcomes of high-grade spondylolisthesis treated by intrasacral fixation, dome resection and circumferential fusion: a retrospective series of 20 consecutive cases with a minimum of 2 years follow-up

PURPOSE

Major concern during surgery for high-grade spondylolisthesis (HGS) is to reduce lumbosacral kyphosis and restore sagittal alignment. Despite the numerous methods described, lumbosacral fixation in HGS is a challenging technique associated with high complication rate. Few series have described outcomes and most of the results are limited to lumbosacral correction without global sagittal alignment analysis. This study aims at analyzing clinical and radiological outcomes of HGS patients treated with intrasacral rods on full spine radiographs.

METHODS

HGS patients (Meyerding III or higher) operated between 2004 and 2014 were reviewed. All patients underwent full spine stereoradiographic images. After L5 and S1 decompression, reduction and circumferential fusion with intrasacral rod fixation and fusion up to L4 were performed under fluoroscopy. The entry points for S1 screws were located 3-5 mm above and 5 mm lateral to the first sacral hole, toward the promontory. The two short distal fusion rods were then positioned into the sacrum guided by anteroposterior fluoroscopy using Jackson's technique. Then, sacral dome resection was performed and a PEEK cage was impacted in L5S1 after reduction. Postoperatively, the hip and knee were kept flexed at 45° for 1 week and extended progressively. Preoperative, 3 months postoperative and last follow-up (> 2 years minimum) clinical and radiographic data were collected. Sagittal parameters included lumbosacral angle (LSA), olisthesis, T1 spinopelvic inclination (T1SPi) and spinopelvic parameters.

RESULTS

20 HGS patients were included (8 ptosis, 5 Meyerding IV). The mean age was 14 years. At final FU (7.2 years ± 3), LSA kyphosis and olisthesis were reduced (65° ± 14 vs 99° ± 11, p < 0.001 and 81% ± 19 vs 45% ± 18, p < 0.001, respectively). While L1L5 lordosis decreased, T1T12 kyphosis increased. At FU, global alignment with T1SPi was - 6° ± 3. No significant loss of correction was observed. Regarding complications, ten patients presented transient L5 motor deficit that occurred when patients were put in standing position. However, all recovered before 3 months postoperatively.

CONCLUSION

Intrasacral rod fixation appears to be an effective technique to correct LSA kyphosis, compensatory hyperlordosis and restore global sagittal alignment with a postoperative T1SPi corresponding to the value of the asymptomatic subject and achieve fusion. However, it remains a demanding technique with high risk of transient neurologic complications.

Outcomes after scoliosis surgery for children with cerebral palsy: a systematic review

AIM

This study aims (1) to evaluate and synthesize the evidence for the postoperative outcomes after scoliosis surgery for children with cerebral palsy (CP), and (2) to identify preoperative risk factors for adverse outcomes after surgery.

METHOD

Medline, EMBASE, CINAHL, and PubMed were searched for relevant literature. Included studies were assessed for risk of bias using the Cochrane Effective Practice and Organisation of Care tool. Quality of evidence for overall function, quality of life (QoL), gross motor function, caregiver outcomes, deformity correction, and postoperative complications were assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation).

RESULTS

Fifty-one studies met inclusion criteria, including 35 case series designs. Risk of bias was high across all studies. On average good deformity correction was achieved, the trend appears positive for caregiver and QoL outcomes, but there was minimal to no change for gross motor or overall function. Inconsistent measurement limited synthesis. A mean overall complication rate of 38.1% (95% confidence interval 27.3-53.3) was found. The quality of evidence was very low across all functional outcomes.

INTERPRETATION

Limited high-quality evidence exists for outcomes after scoliosis surgery in children with CP, a procedure associated with a moderately high complication rate. The intervention appears indicated for deformity correction, but currently there is insufficient evidence to make recommendations for this surgery as a way to also improve functional outcomes, caregiver outcomes, and quality of life.

Predictive factors of intraoperative cell salvage during pediatric scoliosis surgery. Cell saver during scoliosis surgery in children

INTRODUCTION

Blood-saving strategy during spinal surgery in children often includes recombinant erythropoietin (rEPO) and antifibrinolytic therapapy (AFT). The aim of this study was to investigate the efficacy of intraoperative blood salvage in decreasing homologous blood transfusion.

MATERIAL AND METHODS

Using the prospective data from patients operated during a one year period for scoliosis correction, we calculate the predictable hematocrit at day postoperative 1 without the use of blood salvage and compare it to the target hematocrit transfusion according to patient's status. Predictors analyzed were: age, weight, surgical indication, Cobb's angle, ASA status, preoperative hemoglobin, number of level fused, sacral fusion and thoracoplasty. Statistical analyses were performed using a classification tree analysis.

RESULTS

This study included 147 patients. Blood salvage was estimated avoiding homologous blood transfusion in 17 patients. Predictors of the efficacy of blood salvage were: neuromuscular indications, number of level fused and BMI. Blood salvage was found totally ineffective in: patients with no neuromuscular diseases with either: surgeries interesting<13 levels fused or surgeries interesting>13 levels with a preoperative BMI ≥ 21. In all other cases, blood salvage can decrease homologous transfusion. The model exhibited 97% of accurate for the prediction if the inefficacy of blood salvage. The AUCROC of the model was 0.93 [95% confidence interval 0.9 to 0.99] and the overall validation was 60.1% of explained variability.

CONCLUSION

The present study indicates that blood salvage is ineffective under certain circumstances. More studies are mandatory to confirm these results.

Rod Migration Into the Spinal Canal After Posterior Instrumented Fusion Causing Late-Onset Neurological Symptoms

BACKGROUND

Rod migration into the spinal canal after posterior instrumented fusion is a rare complication causing late-onset neurological symptoms. The purpose of the present study is to report a case of a 13-year-old boy with spastic cerebral palsy and related neuromuscular kyphoscoliosis who developed late-onset neurological deterioration secondary to progressive implant migration into the spinal canal over a 5-year period.

METHODS

A decision was made to remove both rods to achieve decompression. Intraoperative findings were consistent with information gained from preoperative imaging. The rods were found to have an intracanal trajectory at T9-T10 for the right rod and T12-L2 for the left rod.

RESULTS

The cause of implant migration, with progressive laminar erosion slow enough to generate a solid mass behind, was progressive kyphosis in a skeletally immature patient with neuromuscular compromise.

CONCLUSIONS

Fixation type, early surgery, and spasticity management contributed significantly to the presenting condition. Mechanical factors and timing of surgery played a decisive role in this particular presentation.

LEVEL OF EVIDENCE

Level IV--Case report and review of the literature.

Experience in Perioperative Management of Patients Undergoing Posterior Spine Fusion for Neuromuscular Scoliosis

The objective of this investigation was to determine the outcome of spine fusion for neuromuscular (NM) scoliosis, using Unit Rod technique, with emphasis on complications related to preoperative general health. Between 1997 and 2007, 96 consecutive patients with neuromuscular scoliosis operated on with Unit Rod instrumentation were retrospectively reviewed. The inclusion criteria were diagnosis of NM scoliosis due to cerebral palsy (CP) and muscular dystrophy (DMD). Patient's preoperative general health, weight, and nutrition were collected. Different radiographic and clinical parameters were evaluated. There were 66 CP patients (59 nonwalking) and 30 DMD patients (24 nonwalking). Mean age at surgery was 16.5 years and 13.9 years, respectively. All radiographic measurements improved significantly. Wound infection rate was 16.7% (11% of reoperation rate in CP; 10% in DMD; 3 hardware removal cases). No pelvic fracture due to rod irritation was observed. Unit Rod technique provides good radiographic and clinical outcomes even if this surgery is associated with a high complication rate. It is a quick, simple, and reliable technique. Perioperative management strategy should decrease postoperative complications and increases outcome. A standardized preoperative patient evaluation and preparation including respiratory capacity and nutritional, digestive, and musculoskeletal status are mandatory prior to surgery.

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.

Past and current use of walking measures for children with spina bifida: a systematic review

OBJECTIVES

To describe walking measurement in children with spina bifida and to identify patterns in the use of walking measures in this population.

DATA SOURCES

Seven medical databases-Medline, PubMed, Embase, Scopus, Web of Science, CINAHL, and AMED-were searched from the earliest known record until March 11, 2014. Search terms encompassed 3 themes: (1) children; (2) spina bifida; and (3) walking.

STUDY SELECTION

Articles were included if participants were children with spina bifida aged 1 to 17 years and if walking was measured. Articles were excluded if the assessment was restricted to kinematic, kinetic, or electromyographic analysis of walking. A total of 1751 abstracts were screened by 2 authors independently, and 109 articles were included in this review.

DATA EXTRACTION

Data were extracted using standardized forms. Extracted data included study and participant characteristics and details about the walking measures used, including psychometric properties. Two authors evaluated the methodological quality of articles using a previously published framework that considers sampling method, study design, and psychometric properties of the measures used.

DATA SYNTHESIS

Nineteen walking measures were identified. Ordinal-level rating scales (eg, Hoffer Functional Ambulation Scale) were most commonly used (57% of articles), followed by ratio-level, spatiotemporal measures, such as walking speed (18% of articles). Walking was measured for various reasons relevant to multiple health care disciplines. A machine learning analysis was used to identify patterns in the use of walking measures. The learned classifier predicted whether a spatiotemporal measure was used with 77.1% accuracy. A trend to use spatiotemporal measures in older children and those with lumbar and sacral spinal lesions was identified. Most articles were prospective studies that used samples of convenience and unblinded assessors. Few articles evaluated or considered the psychometric properties of the walking measures used.

CONCLUSIONS

Despite a demonstrated need to measure walking in children with spina bifida, few valid, reliable, and responsive measures have been established for this population.

Posterior spinal fusion to sacrum in non-ambulatory hypotonic neuromuscular patients: sacral rod/bone graft onlay method

PURPOSE

A retrospective study involving 65 non-ambulatory patients with hypotonic neuromuscular scoliosis has assessed the effectiveness of a sacral rod/bone onlay technique for extending spinal fusion to the sacrum.

METHODS

To extend posterior spinal fusion to the sacrum, we used either 1 Harrington rod and 1 Luque L rod with sublaminar wires in 14 patients (Group 1) or two rods with sublaminar wires in 51 patients (Group 2) along with abundant autograft and allograft bone covering the ends of the rods.

RESULTS

Diagnoses were Duchenne muscular dystrophy 53, spinal muscular atrophy 4, myopathy 3, limb girdle muscular dystrophy 2, infantile FSH muscular dystrophy 1, cerebral palsy 1, and Friedreich ataxia 1. Mean age at surgery was 14.3 years (±2.2, range 10.9-25.2). Radiographic follow-up (2 years post-surgery or greater) was 6.4 years (±4.4, range 2-25.3). Using the onlay technique, all patients fused with no rod breakage or pseudarthrosis. For the entire series, the mean pre-operative scoliosis was 54.7° (±31.1, range 0°-120°) with post-operative correction to 21.8° (±21.7, range 0°-91°) and long-term follow-up 24° (±22.9, range 0°-94°). For pelvic obliquity, pre-operative deformity was 17.3° (±11.3, range 0°-51°) with post-operative correction to 8.9° (±7.8, range 0°-35°) and long-term follow-up 10.1° (±8.1, range 0°-27°). Five required revision at a mean of 3.3 years post-original surgery involving rod shortening at the distal end. One of these had associated infection.

CONCLUSION

Lumbosacral stability and long-term sitting comfort have been achieved in all patients. Problems can be minimized by positioning the rods firmly against the sacrum at the time of surgery with a relatively short extension beyond the L5-S1 junction. The procedure is valuable in hypotonic non-ambulatory neuromuscular patients whose immobility enhances the success rate for fusion due to diminished stress at the lumbosacral junction. It is particularly warranted for those with osteoporosis and a small, deformed pelvis. Considerable weight loss and lengthy rods not closely apposed to the sacrum at the time of surgery played a major role in patients needing revision.

Lumbosacral arthrodesis for neuromuscular scoliosis using a simplified Jackson technique

Treating patients with severe neuromuscular scoliosis by long spinal fusion improves their quality of life and provides significant comfort for the patient and caregivers. But lumbosacral (L5-S1) fusion is challenging in these patients because of the significant deformities that result in poor bone anchoring quality and a risk of impingement between the skin and implants. In 1993, Jackson described a L5-S1 fusion technique using S1 pedicle screws and intrasacral rods (implanted under X-ray guidance) that are linked to the construct above with connectors. The goal of this study was to evaluate the clinical and radiological results and the postoperative complications of a simplified version of this technique, which does not require connectors or X-ray guidance.

MATERIALS AND METHODS

Thirty-three patients were evaluated with a minimum follow-up of 4years (average 82months). Frontal balance, sagittal balance, Cobb angle, sacral slope, lumbar lordosis and lateral pelvic tilt in the frontal plane were assessed on preoperative, postoperative and follow-up X-rays. Intraoperative and postoperative complications were recorded.

RESULTS

Complete fusion was obtained in 32 patients. The average Cobb angle was 62° initially and was reduced to 20° after surgery and 24° at the final follow-up. The average lateral pelvic tilt was 10.3° (0 to 26°) initially; it was surgically corrected to an average of 7.5° (0 to 24°); the average secondary loss of correction was 1.2° (0 to 9°). The sacral slope was corrected to an average of 11.2°; an average of 0.2° had been lost at the last follow-up (0 to 18°). Although the average for lumbar lordosis was unchanged, the standard deviation went from 29° to 16° after the corrective surgery and 17° at the last follow-up, with large cluster of measurements around the average value of 40°. The deformity correction was comparable to the results with other techniques (Galveston, sacroiliac screws); the complication rate was similar but the non-union rate was lower. This simplified Jackson technique appears to be an effective, simple method for L5-S1 fusion to correct neuromuscular scoliosis as it provides stable results over time.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Posterior second sacral alar iliac screw insertion: anatomic study in a Chinese population

OBJECTIVE

To provide radiographic parameters for optimal placement of posterior second sacral alar iliac (S2AI) screw for instrumentation and fusion of scoliosis to the second sacral level in a Chinese population.

METHODS

S2AI screw trajectories were mapped on three-dimensional computed tomography (3DCT) reconstructions of 60 normal adult pelvises. 1 mm inferior and 1 mm lateral to the S1 dorsal foramen were chosen as the entry point, and ideal S2AI screw trajectories were explored by rotating and cutting the 3D pelvis, ensuring that the trajectories were of maximum length and width. The directions and depth of these determined trajectories were then measured.

RESULTS

The ideal S2AI screw trajectories could be found in each pelvis. The left and right screw trajectory parameters for males were shown as follows: angulation was L 29.15 ± 8.60° vs. R 29.96 ± 8.28° (p = 0.286) caudally in the sagittal plane and L 36.49 ± 3.14° vs. R 37.16 ± 3.14° (p = 0.165) laterally in the transverse plane. The maximal and intrasacral lengths of trajectory were L 121.25 ± 8.33 vs. R 120.63 ± 7.54 mm (p = 0.460) and L 26.20 ± 3.31 vs. R 26.92 ± 4.76 mm (p = 0.268). The entry point was L 28.87 ± 3.33 vs. R 29.79 ± 3.55 mm (p = 0.186) lateral to the second sacral midline, and L 44.14 ± 11.87 vs. R 43.89 ± 12.53 mm (p = 0.687) underneath the skin. The trajectories for females were more caudal (L: 34.50 ± 6.56° vs. 29.15 ± 8.60°, p = 0.009; R: 35.72 ± 7.53° vs. 29.96 ± 8.28°, p = 0.007) in the sagittal plane, but the lateral angulation in the transverse plane showed no difference between genders (p > 0.05). The female iliac medullar cavities were obviously narrower than those of males (L: 14.76 ± 2.46 vs. 16.98 ± 3.52, p = 0.006; R: 14.94 ± 2.60 vs. 17.00 ± 2.81, p = 0.005). Although the average maximal length of trajectories for females were about 5 mm shorter than those of males, intrasacral length were equal to those of males. Furthermore, both the distance from entry point to the S2 midline and skin in the transverse plane showed no difference between genders.

CONCLUSION

The feasibility to insert S2AI screws to the sacrum and ilium in an Asian population along with the ideal entry angle and length of trajectory were identified for clinical practice.

Pelvic fixation for neuromuscular scoliosis deformity correction

Pelvic fixation is most frequently indicated in the pediatric population for the treatment of neuromuscular scoliosis with significant pelvic obliquity. Neuromuscular scoliosis surgery is associated with a high risk of complications, and this is further increased by extension of fusion to the sacrum. Numerous techniques have been described for pelvic fixation associated with a long spine fusion each with its own set of specific benefits and risks. This article reviews the contemporary surgical techniques of pelvic fixation used to extend a spine fusion to the sacrum and pelvis focusing on the management of neuromuscular scoliosis, including their biomechanical rationale, results, and complications.

A new pelvic rod system for the surgical correction and fixation of pelvic obliquity in pediatric neuromuscular scoliosis

PURPOSE

To describe surgical outcomes using the new device in pediatric neuromuscular scoliosis.

METHODS

All patients with neuromuscular disorders requiring surgery with pelvic fixation for the correction of scoliosis in the period 2002-2009 were operated by the new pelvic rod fixation device. Coronal and sagittal alignment before and after surgery until the latest follow-up were evaluated by standard X-rays. Intraoperative and postoperative complications were recorded.

RESULTS

All 18 study patients (mean age at surgery 15 years, range 10-27) achieved solid fusion at a mean follow-up of 41 months. The coronal Cobb angle improved from 82° ± 31° (range 36-168) to 33° ± 25° at the last follow-up (range 9-95 months) (P < 0.0001). Pelvic obliquity improved from 19° ± 6° (range 10-30) to 5° ± 5° (range 0-14) (P < 0.0001). Early complications included pneumonia, urinary tract infection, disseminated intravascular coagulation (DIC), and hypovolemic shock. Three patients required debriding and received prolonged antimicrobial therapy for deep wound infection (none required implant removal). At the latest follow-up, no patient complained of lumbar pain or worsening of ambulatory status or level of activity.

CONCLUSION

Surgery employing the new pelvic rod fixation device allowed solid fusion and fixation with significant correction of multiplanar deformity, but the complication rate was high.