Long posterior fixation of the spine to the sacrum and pelvis

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.

Matched-pair cohort study of 1-year patient-reported outcomes following pelvic fixation

BACKGROUND CONTEXT

Pelvic fixation improves fusion and stability for thoracolumbar constructs that extend across the L5-S1 junction. No patient-reported outcomes have been published to evaluate patients' functional outcomes following these procedures compared with pelvis-sparing procedures.

PURPOSE

The goal of this study is to identify the effect of pelvic fixation on both objective and patient-reported outcomes.

STUDY DESIGN/SETTING

This was a retrospective, matched cohort study.

PATIENT SAMPLE

The sample comprised adult patients undergoing spine surgery at our institution who had complete 1-year postoperative follow-up.

OUTCOME MEASURES

Patient-reported outcome instruments (Oswestry Disability Index [ODI], Short-Form 12-item survey, and EuroQol-5D) and objective measures (length of hospital stay, discharge disposition, postoperative complications, and readmission rates) were considered.

METHODS

We identified patients in our outcomes registry undergoing instrumented spinal fusion involving the pelvis between October 2010 and May 2014 who had 1-year follow-up data. Nearest-neighbor 1:1 matched controls were identified using propensity scoring from the cohort of patients undergoing any spinal procedure which extended caudally to the lumbar spine or sacrum. Objective and patient-reported outcomes were compared between cases and controls.

RESULTS

There were 44 patients who underwent spinal procedures involving the pelvis and had 1-year follow-up data. An equal number of controls were identified and had similar baseline demographic and clinical characteristics. No significant differences were found among operative variables or objective complication rates. Patients undergoing pelvic fixation had moderately greater improvement at 3 months as measured by ODI, but this difference was not present at 1 year. Other patient-reported outcome measures were equivocal between groups.

CONCLUSIONS

This matched cohort study demonstrates that inclusion of the pelvis in spinal hardware constructs is not associated with increased complications and may slightly improve patient disability at 1 year. Given that pelvic fixation may reduce L5-S1 breakdown and improve biomechanics, surgeons should more readily include the pelvis in instrumented fusion procedures.

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.

Surgical management of spinal deformities in cerebral palsy. A review

Cerebral palsy (CP) spinal deformities encompass a spectrum of deformities that are often initially treated nonoperatively, only to result in progression of scoliotic curves and further morbidity. Various surgical interventions have been devised to address the progressive curvature of the spine. This endeavor cannot be taken lightly and at times can be encumbered by prior treatments such as the use of baclofen pumps or dorsal rhizotomies. Care of these patients requires a multidisciplinary approach and comprehensive preoperative and postoperative management, including nutritional status, orthopedic assessment of functional level with specific emphasis on the hips and pelvic obliquity, and wheelchair modifications. The surgical techniques in CP scoliosis have progressively evolved from the classic Luque-Galveston fixation methods, the use of unit rods, and lately the use of pedicle screws, to modern sacropelvic fixation. With the latter method, the spinal deformity in patients with CP can usually be almost completely corrected.

Three-dimensional image-guided placement of S2 alar screws to adjunct or salvage lumbosacral fixation

BACKGROUND CONTEXT

Achieving fusion across the lumbosacral junction is challenging because of the unfavorable biomechanics associated with ending a fusion at this level. Bicortical placement of S1 pedicle screws can increase the construct stability at the lumbosacral junction; however, construct failure and pseudoarthrosis can still result. Iliac screws have been shown to increase the stiffness of lumbosacral constructs, but disadvantages include difficulty in connecting the iliac screw to adjacent sacral screws, painful screw loosening or prominence requiring removal, and the inability to place the screws in some patients with previous iliac crest autograft harvest.

PURPOSE

The purpose of the study is to describe a technique of S2 alar screw placement using three-dimensional image guidance.

STUDY DESIGN/SETTING

The study design is a retrospective analysis.

PATIENT SAMPLE

Twenty patients undergoing lumbosacral fusion had 32 screws placed using this technique.

OUTCOME MEASURES

An independent radiologist graded screw placement and lumbosacral fusion on thin-cut postoperative computed tomographic (CT) scans.

METHODS

Image guidance in this study was accomplished with the Medtronic Stealth Station Treon (Medtronic Inc., Littleton, MA, USA) used in conjunction with the O-ARM (Medtronic Inc.). Indications for placement of S2 alar screws included the following: to adjunct S1 pedicle screws in multilevel fusion cases; as an adjunct or alternative to S1 pedicle screws in pseudoarthrosis revision cases in which the S1 screws had loosened; as an alternative to S1 pedicle screws in cases where medial trajectory of an S1 pedicle screw was difficult to obtain because of a low-set lumbosacral junction; and a combination of the above. The entry point of the screw was typically chosen lateral and superior to the S2 dorsal foramen with the trajectory directed anterior, inferior, and lateral. Attempt was made to place the screw with the tip purchasing, but not penetrating through, the triangular area of cortical bone that can be found at the anterior, inferior, and lateral boundary of the sacral ala. An independent radiologist graded the placement of the screws on the intraoperative CT scan obtained with the O-ARM or on postoperative CT scans. Lumbosacral fusion was assessed on postoperative CT scans obtained at follow-up.

RESULTS

No complications occurred in this study as a result of S2 alar screw placement or image guidance. Five screws did penetrate the anterior cortex of the sacrum, with no clinical consequence. At the time of abstract submission, 16 patients were able to have follow-up CT scans, 15 of which were graded as solid fusion at the lumbosacral junction by the grading radiologist.

CONCLUSIONS

Three-dimensional image guidance allows for safe placement of large S2 sacral alar screws that can provide additional biomechanical stability to lumbosacral constructs or serve as an alternate point of sacral fixation when S1 pedicle screws cannot be salvaged or placed in a medial trajectory.