Posterior Column Osteotomy Research Articles

Intraoperative Neuromonitoring During Adult Spinal Deformity Surgery: Alert-Positive Cases for Various Surgical Procedures

Study DesignRetrospective study. ObjectivesTo analyze intraoperative neuromonitoring (IONM) alerts in various surgical procedures and clarify incidences and causes of IONM alarms in consecutive adult spinal deformity (ASD) surgeries. Summary of Background DataASD surgery has a high neurologic complication rate. IONM may play a role in identifying and preventing neurologic complications. MethodsThis study included 275 consecutive ASD patients treated by posterior corrective fusion who had been followed up for more than two years. We divided the patients into 1) the PCO group: multiple posterior column osteotomies; and 2) the 3CO group: three-column osteotomy including pedicle subtraction osteotomy and vertebral column resection. We set a 70% amplitude reduction as the alarm point for transcranial electrical stimulation motor-evoked potentials (Tc-MEPs) using 32-channel IONM. ResultsThe PCO and 3CO groups included 162 and 113 cases, respectively. IONM revealed 32 cases (11.6%) of Tc-MEP alerts, 10.4% in the PCO group, and 13.2% in the 3CO group. Postoperative follow-ups revealed 15 cases (5.5%) of new neurologic deficits, 4.9% in the PCO group, and 6.2% in the 3CO group. Most IONM alarms in the PCO group appeared at the time of rod rotation maneuvers, and 88.9% of alarms were selective for MEP decrease. In contrast, IONM alarms in the 3CO group appeared at the time of spinal shortening, and 80% were global MEP decreases. Immediately after the alarm, neurologic deficits might be rescued by foraminal decompression after rod rotation and by adjusting the length of spinal shortening. Overall, more than 50% of cases with IONM alerts were rescued by intraoperative additional management. ConclusionIONM reduced the incidence of neurologic complications in ASD surgery. Spinal surgeons should recognize the type of muscle derivation and respond to such alerts by performing appropriate corrections reflecting the mechanism underlying the neural damage. Level of EvidenceLevel IV.

Factors for the acquisition of 10° angular change at the lumbar spine through posterior column osteotomy in adult spinal deformity surgery.

OBJECTIVEPosterior column osteotomy (PCO) has been known to provide an angular change (AC) of approximately 10° in sagittal plane deformity. However, whether PCO can actually obtain an AC of ≥ 10° depending on the particular level in the lumbar spine and which factors can effect a gain of ≥ 10° AC after PCO remain to be elucidated. The aim of this study was to identify the factors that effect a gain of ≥ 10° AC through PCO by comparing radiographic measurements between an AC group and a control group before and after adult spinal deformity (ASD) surgery.METHODSForty consecutive patients who underwent multilevel PCOs for ASD at a single institution between 2012 and 2016 were included in this study. PCO was performed in 142 disc space levels in the lumbar spine. The authors defined the disc space level that obtained ≥ 10° AC in the sagittal plane by PCO as the AC group and the remaining patients as controls. The modified Pfirrmann grade, surgical level, implementation of the transforaminal lumbar interbody fusion (TLIF), and radiographic measurements were compared between the groups.RESULTSThere were 67 levels in the AC group and 75 in the control group. Multivariate analysis identified the surgical level at L4-5 (OR 3.802, 95% CI 1.127-12.827, p = 0.031), performing TLIF with PCO (OR 3.303, 95% CI 1.258-8.674, p = 0.015), and a preoperative kyphotic disc space angle (OR 1.397, 95% CI 1.231-1.585, p < 0.001) as the factors that significantly effected ≥ 10° AC in the sagittal plane after PCO.CONCLUSIONSIn ASD surgery, PCO cannot always achieve ≥ 10° AC in the sagittal plane. The factors that effected ≥ 10° AC in PCO for ASD were surgical level at L4-5, performing TLIF with PCO, and the preoperative kyphotic disc space angle.

Lordosis Recreation in Transforaminal and Posterior Lumbar Interbody Fusion: A Cadaveric Study of the Influence of Surgical Bone Resection and Cage Angle.

Controlled cadaveric study of surgical technique in transforaminal and posterior lumbar interbody fusion (TLIF and PLIF) OBJECTIVE.: To evaluate the contribution of surgical techniques and cage variables in lordosis recreation in posterior interbody fusion (TLIF/PLIF). The major contributors to lumbar lordosis are the lordotic lower lumbar discs. The pathologies requiring treatment with segmental fusion are frequently hypolordotic or kyphotic. Current posterior based interbody techniques have a poor track record for recreating lordosis, although recreation of lordosis with optimum anatomical alignment is associated with better outcomes and reduced adjacent segment change needing revision. It is unclear whether surgical techniques or cage parameters contribute significantly to lordosis recreation. Eight instrumented cadaveric motion segments were evaluated with pre and post experimental radiological assessment of lordosis. Each motion segment was instrumented with pedicle screw fixation to allow segmental stabilization. The surgical procedures were unilateral TLIF with an 18° lordotic and 27 mm length cage, unilateral TLIF (18°, 27 mm) with bilateral facetectomy, unilateral TLIF (18°, 27 mm) with posterior column osteotomy (PCO), PLIF with bilateral cages (18°, 22 mm), and PLIF with bilateral cages (24°, 22 mm). Cage insertion used and "insert and rotate" technique. Pooled results demonstrated a mean increase in lordosis of 2.2° with each procedural step (lordosis increase was serially 1.8°, 3.5°, 1.6°, 2.5°, and 1.6° through the procedures). TLIF and PLIF with PCO increased lordosis significantly compared with unilateral TLIF and TLIF with bilateral facetectomy. The major contributors to lordosis recreation were PCO, and PLIF with paired shorter cages rather than TLIF. This study demonstrates that the surgical approach to posterior interbody surgery influences lordosis gain and PCO optimizes lordosis gain in TLIF. The bilateral cages used in PLIF are shorter and associated with further gain in lordosis. This information has the potential to aid surgical planning when attempting to recreate lordosis to optimize outcomes. N/A.

Complications of Posterior Column Osteotomies in the Pediatric Spinal Deformity Patient

BackgroundIn spinal deformity surgery, posterior column osteotomies (PCOs) are used to increase spinal flexibility and permit greater deformity correction, while avoiding the morbidity of anterior column surgery. Complications related to use of PCOs have been well characterized in adults; however, there is a paucity of information in the pediatric population. MethodsA single-surgeon retrospective analysis was completed of 484 PCOs in 142 patients (average age: 14.5 years) undergoing spinal deformity surgery. All surgeries were completed by a standard posterior approach using a midline incision and dual-rod, pedicle screw constructs. PCO-related complications were recorded (intraoperative monitoring alerts, postoperative neurologic deficit, dural tear/violations, cerebrospinal fluid [CSF] leak, pseudarthrosis, etc.) and analyzed by diagnosis (idiopathic, congenital, neuromuscular, syndromic). ResultsThe diagnoses for the 142 patients were idiopathic (103 patients), neuromuscular (23 patients), syndromic (14 patients), and congenital (2 patients). In a subset of 87 patients with 2-year radiographic follow-up, the preoperative major coronal Cobb measurement was 75.5° ± 17.6°, which corrected to 34.9° ± 17.5° postoperatively and 37.8° ± 17.9° at last follow-up (p < .0001, p < .0001). Complications evaluated were postoperative neurologic deficit (0% of patients, 0/142), dural tears/violations at site of PCO (0.4% of PCOs, 2/484), CSF leak (0% of patients, 0/142), and pseudoarthrosis at site of PCO (0% of PCOs, 0/290). ConclusionThe overall frequency of complications related to PCOs was 0.4% (0.4% dural tears/violations) with 0% postoperative neurologic deficit, CSF leak, or pseudarthrosis. Based on these data, PCOs appear to be a safe technique in pediatric spine deformity surgery, with a low rate of technique-related complications. Study DesignRetrospective case series. ObjectivesTo report the frequency of posterior column osteotomy complications (neurologic deficit, dural tear, cerebrospinal fluid leak, and pseudarthrosis) in pediatric patients undergoing spinal deformity surgery. Level of EvidenceLevel IV.

Pedicle Subtraction Osteotomy Versus Multiple Posterior Column Osteotomies in Severe and Rigid Neuromuscular Scoliosis.

Retrospective analysis. The aim of this study is to compare the safety and efficacy of the apical pedicle subtraction osteotomy (PSO) technique with multiple posterior column osteotomies (PCOs) in nonambulatory patients with severe, rigid neuromuscular scoliosis. Neuromuscular scoliosis frequently causes intolerance to sitting due to pelvic obliquity, trunk decompensation, and associated back and rib impingement pain which diminish the patient's functional capacity. In the case of rigid curves, spinal osteotomy techniques are occasionally required for effective correction. We retrospectively reviewed our patients with severe and rigid neuromuscular scoliosis with associated pelvic obliquity who were treated with posterior instrumented fusion extending to pelvis with more than 1-year postoperative follow-up. We compared radiological and clinical results of PSO and multiple PCO techniques in severe rigid neuromuscular scoliosis with pelvic obliquity of more than 15° in traction radiograph under general anesthesia. Hospital records were also reviewed for operative time, intraoperative blood loss, amount of blood transfusion, duration of hospital stay, and complications. There were 12 patients in the PSO group and 10 patients in the PCO group. There was no significant difference between groups in terms of major curve magnitude, sagittal parameters or pelvic obliquity. Although not statistically significant, PSO technique did trend toward better scoliosis correction (post-op Cobb angle 56.1° vs. 66.7° [P = 0.415]). PSO technique provided a significantly better correction in pelvic obliquity (59% vs. 84%) (P = 0.001). There was no significant difference in average intraoperative blood loss, transfusion, and operative times including anesthesia time, hospital stay, or complications. PSO may be an option in correction of severe and rigid neuromuscular scoliosis. It provides better correction of pelvic obliquity without increasing operative time, need for transfusion, or duration of hospitalization as compared to multiple apical PCO technique. Traction radiograph under general anesthesia is a valuable tool in surgical decision making. 4.

Complications of 487 Posterior-Column Osteotomies in Pediatric Spinal Deformity

Title: Complications of 487 Posterior-Column Osteotomies in Pediatric Spinal Deformity Summary: A retrospective analysis was performed on 487 PCOs in 143 pediatric patients (average age 14.6 yrs.) with major curve Cobb of 75.34° ± 17.61° preoperatively, corrected to 38.08° ± 18.03° at last follow-up. Overall complication rate was 1.1% with no neurologic deficits or cerebrospinal fluid leaks postoperatively. Dural tears at the site of PCOs and pseudarthroses occurred at 0.4% and 0.7% of all PCOs, respectively. Hypothesis: Posterior column osteotomies performed during posterior spinal fusion (PSF) are …

Restoration of Sagittal Balance in Spinal Deformity Surgery.

The prevalence of patients with adult spinal deformity (ASD) has been reported as high as 68%. ASD often leads to significant pain and disability. Recent emphasis has been placed on sagittal plane balance and restoring normal sagittal alignment with regards to the three dimensional deformity of ASD. Optimal sagittal alignment has been known to increase spinal biomechanical efficiency, reduce energy expenditure by maintaining a stable posture with improved load absorption, influence better bony union, and help to decelerate adjacent segment deterioration. Increasingly positive sagittal imbalance has been shown to correlate with poor functional outcome and poor self-image along with poor psychological function. Compensatory mechanisms attempt to maintain sagittal balance through pelvic rotation, alterations in lumbar lordosis as well as knee and ankle flexion at the cost of increased energy expenditure. Restoring normal spinopelvic alignment is paramount to the treatment of complex spinal deformity with sagittal imbalance. Posterior osteotomies including posterior column osteotomies, pedicle subtraction osteotomies, and posterior vertebral column resection, as well anterior column support are well known to improve sagittal alignment. Understanding of whole spinal alignment and dynamics of spinopelvic alignment is essential to restore sagittal balance while minimizing the risk of developing sagittal decompensation after surgical intervention.

Preliminary results of anterior lumbar interbody fusion, anterior column realignment for the treatment of sagittal malalignment

OBJECTIVE Sagittal malalignment decreases patients' quality of life and may require surgical correction to achieve realignment goals. High-risk posterior-based osteotomy techniques are the current standard treatment for addressing sagittal malalignment. More recently, anterior lumbar interbody fusion, anterior column realignment (ALIF ACR) has been introduced as an alternative for correction of sagittal deformity. The objective of this paper was to report clinical and radiographic results for patients treated using the ALIF-ACR technique. METHODS A retrospective study of 39 patients treated with ALIF ACR was performed. Patient demographics, operative details, radiographic parameters, neurological assessments, outcome measures, and preoperative, postoperative, and mean 1-year follow-up complications were studied. RESULTS The patient population comprised 39 patients (27 females and 12 males) with a mean follow-up of 13.3 ± 4.7 months, mean age of 66.1 ± 11.6 years, and mean body mass index of 27.3 ± 6.2 kg/m2. The mean number of ALIF levels treated was 1.5 ± 0.5. Thirty-three (84.6%) of 39 patients underwent posterior spinal fixation and 33 (84.6%) of 39 underwent posterior column osteotomy, of which 20 (60.6%) of 33 procedures were performed at the level of the ALIF ACR. Pelvic tilt, sacral slope, and pelvic incidence were not statistically significantly different between the preoperative and postoperative periods and between the preoperative and 1-year follow-up periods (except for PT between the preoperative and 1-year follow-up, p = 0.018). Sagittal vertical axis, T-1 spinopelvic inclination, lumbar lordosis, pelvic incidence-lumbar lordosis mismatch, intradiscal angle, and motion segment angle all improved from the preoperative to postoperative period and the preoperative to 1-year follow-up (p < 0.05). The changes in motion segment angle and intradiscal angle achieved in the ALIF-ACR group without osteotomy compared with the ALIF-ACR group with osteotomy at the level of ACR were not statistically significant. Total visual analog score, Oswestry Disability Index, and Scoliosis Research Society-22 scores all improved from preoperative to postoperative and preoperative to 1-year follow-up. Fourteen patients (35.9%) experienced 26 complications (15 major and 11 minor). Eleven patients required reoperation. The most common complication was proximal junctional kyphosis (6/26 complications, 23%) followed by vertebral body/endplate fracture (3/26, 12%). CONCLUSIONS This study showed satisfactory radiographic and clinical outcomes at the 1-year follow-up. Proximal junctional kyphosis was the most common complication followed by fracture, complications that are commonly associated with sagittal realignment surgery and may not be mitigated by the anterior approach.

Health-related quality of life outcomes in complex adult spinal deformity surgery.

OBJECTIVE Significant health-related quality of life (HRQOL) benefits have been observed for patients undergoing primary and revision adult spinal deformity (ASD) surgery. The purpose of this study was to report changes in HRQOL measures in a consecutive series of patients undergoing complex spinal reconstructive surgery, using Scoli-RISK-1 (SR-1) inclusion criteria. METHODS This was a single-center, retrospective cohort study. The SR-1 inclusion criteria were used to define patients with complex ASD treated between June 1, 2009, and June 1, 2011. Standard preoperative and perioperative data were collected, including the Scoliosis Research Society (SRS)-22r instrument. The HRQOL changes were evaluated at a minimum 2-year follow-up. Standardized forms were used to collect surgery-related complications data for all patients. Complications were defined as minor, transient major, or permanent major. Patients who achieved a minimum 2-year follow-up were included in the analysis. RESULTS Eighty-four patients meeting SR-1 criteria were identified. Baseline demographic and surgical data were available for 74/84 (88%) patients. Forty-seven of 74 (64%) patients met the additional HRQOL criteria with a minimum 2-year follow-up (mean follow-up 3.4 years, range 2-6.5 years). Twenty-one percent of patients underwent posterior fusion only, 40% of patients had a posterior column osteotomy, and 38% had a 3-column osteotomy. Seventy-five percent of patients underwent a revision procedure. Significant improvements were observed in all SRS-22r domains: Pain: +0.8 (p < 0.001); Self-Image: +1.4 (p < 0.001); Function: +0.46 (p < 0.001); Satisfaction: +1.6 (p < 0.001); and Mental Health: +0.28 (p = 0.04). With the exception of Mental Health, more than 50% of patients achieved a minimum clinically important difference (MCID) in SRS-22r domain scores (Mental Health: 20/47, 42.6%). A total of 65 complications occurred in 31 patients. This includes 29.8% (14/47) of patients who suffered a major complication and 17% (8/47) who suffered a postoperative neurological deficit, most commonly at the root level (10.6%, 5/47). Of the 8 patients who suffered a neurological deficit, 1 (13%) was able to achieve MCID in the SRS Function domain. CONCLUSIONS The majority of patients experienced clinically relevant improvement in SRS-22r HRQOL scores after complex ASD surgery. The greatest improvements were seen in the SRS Pain and SRS Self-Image domains. Although 30% of patients suffered a major or permanent complication, benefits from surgery were still attained. Patients sustaining a neurological deficit or major complication were unlikely to achieve HRQOL improvements meeting or exceeding MCID for the SRS Function domain.

Multilevel Schwab grade II osteotomies for sagittal plane correction in the management of adult spinal deformity

Background ContextPrior reports have compared posterior column osteotomies with pedicle subtraction osteotomies in terms of utility for correcting fixed sagittal imbalance in adolescent patients with deformity. No prior reports have described the use of multilevel Smith-Petersen Osteotomies (SPOs) alone for surgical correction in the adult spinal deformity (ASD) population. PurposeThe study aimed to determine the utility of multilevel SPOs in the management of global sagittal imbalance in ASD patients. Study Design/SettingThis is a retrospective observational study at a single academic center. Patient SampleThe sample included 85 ASD patients. Outcome MeasuresThis is a radiographic outcomes cohort study. MethodsThe radiographs of 85 ASD patients were retrospectively evaluated before and after long-segment (>5 spinal levels) fusion and multilevel SPO (≥3 levels) for sagittal imbalance correction. The number of osteotomies, correction in regional lumbar lordosis (LL), and correction per osteotomy was evaluated. Independent predictors of correction per SPO were evaluated with a hierarchical linear regression analysis. ResultsEighty-five patients (mean age: 67.5±11 years) were identified with ASD (372 SPOs). The mean preoperative sagittal vertical axis (SVA) and T1 pelvic angle (TPA) were 8.16±6.75 cm and 25°±13.23°, respectively. The mean postoperative central sacral vertical line (CSVL) and SVA were 0.67±0.70 cm and 1.29±5.41 cm, respectively. The mean improvement in SVA was 6.29 cm achieved with a correction of approximately 5.05° per SPO. The mean LL restoration was 20.3°±13.9°, and 33(39%) patients achieved a final pelvic incidence minus lumbar lordosis (PI-LL) ≤10°. Fifty-four (64%) achieved a postoperative PI-LL ≤15°, 75 (88%) with a PI-LL ≤20°, and 85 (100%) achieved a PI-LL ≤25°. Correction per SPO was similar regardless of prior fusion (4.87° vs. 5.72° for revisions, p=.192). In a subgroup analysis of SVA greater than 10 cm, there was no significant difference in the final LL, thoracic kyphosis, PI-LL, SVA, CSVL, and TPA, as compared with SVA <10 cm. The LL was the only independent predictor of osteotomy correction per level (LL: β coefficient=−0.108, confidence interval: −0.141 to 0.071, p<.0001). ConclusionsMultilevel SPOs are feasible for restoration of LL as well as sagittal and coronal alignment in the ASD population with or without prior instrumented fusion.

Spinal osteotomies: indications, limits and pitfalls.

The aims of spinal deformity surgery are to achieve balance, relieve pain and prevent recurrence or worsening of the deformity.The main types of osteotomies are the Smith-Petersen osteotomy (SPO), pedicle subtraction osteotomy (PSO), bone-disc-bone osteotomy (BDBO) and vertebral column resection (VCR), in order of increasing complexity.SPO is a posterior column osteotomy in which the posterior ligaments and the facet joints are removed and correction is performed through the disc space. A mobile anterior disc is essential. SPO is best in patients with +6-8 cm C7 plumbline. The amount of correction is 9.3° to 10.7°/level (1°/mm bone).PSO is a technique where the posterior elements and pedicles are removed. Then a triangular wedge through the pedicles is removed and the posterior spine is shortened using the anterior cortex as a hinge. The ideal candidates are patients with a severe sagittal imbalance. A single level osteotomy can produce 30° 40° of correction. A single level osteotomy may restore global sagittal balance by an average of 9 cm with an upper limit of 19 cm.BDBO is an osteotomy done above and below a disc level. A BDBO provides correction rates in the range of 35° to 60°. The main indications are deformities with the disc space as the apex and severe sagittal plane deformities.VCR is indicated for rigid multi-planar deformities, sharp angulated deformities, hemivertebra resections, resectable spinal tumours, post-traumatic deformities and spondyloptosis. The main indication for a VCR is fixed coronal plane deformity.The type of osteotomy must be chosen mainly according to the aetiology, type and apex of the deformity. One may start with SPOs and may gradually advance to complex osteotomies.Cite this article: EFORT Open Rev 2017;2:73-82.DOI: 10.1302/2058-5241.2.160069

Multimodal nerve monitoring during periacetabular osteotomy identifies surgical steps associated with risk of injury.

Sciatic nerve palsy after periacetabular osteotomy (PAO) is a serious complication. The purpose of this study was to determine whether a multimodal sciatic monitoring technique allows for identification of surgical steps that place the sciatic nerve at risk. Transcranial electrical motor evoked potentials (TcMEPs), somatosensory evoked potentials (SSEPs), and spontaneous electromyography (EMG) were monitored in a consecutive series of 34 patients (40 hips) who underwent PAO for the treatment of symptomatic hip dysplasia between January 2012 and November 2014. There were 29 females (85%) and five males (15%) with an average age of 19years (range, 12-36 years) at the time of surgery. We detected eight temporary sciatic nerve monitoring alerts in six patients (incidence of 15%). The events included decrease in amplitude of the TcMEPs related to the position of the hip during incomplete ischium osteotomy and placement of a retractor in the sciatic notch during the posterior column osteotomy (N = 3), generalized bilateral decrease in TcMEPs during fragment manipulation and fixation in association with acute blood loss (N = 2), and a change in SSEPs during a superior pubic osteotomy and supra-acetabular osteotomy (N = 1). At the end of the procedure, TcMEPs and SSEPs were at baseline and there was no abnormal pattern on EMG in all patients. Post-operatively, at two, six, 12weeks, and six and 12months, no motor weakness or sensory deficits were noted. Multimodal neuromonitoring allowed for identification of intra-operative steps and maneuvers that potentially place the sciatic nerve at higher risk of injury.

Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study.

Background:In an effort to minimize rod fractures and nonunion in pedicle subtraction osteotomy (PSO) constructs, surgeons have adopted multirod constructs and interbody cages. Anterior column realignment (ACR) with posterior column osteotomies is a minimally invasive alternative to PSO in sagittal balance correction, however, there is a paucity of evidence with respect to rod survival.Methods:Three-dimensional (3D) finite-element-model of a T12-sacrum spine segment was used to compare a 25° PSO at L3 and an ACR with a posterior column osteotomy and 30° hyperlordotic interbody cage at L3–4. The amount of overall T12–S1 lordosis correction was the same for each condition. Each simulation included cobalt chromium alloy primary rods with: (1) PSO; (2) PSO with an interbody cage (IB) at L2–3 (PSO+IB); (3) PSO with accessory (A) rods and IB at L2–3 (PSO+IB+A); (4) PSO with satellite (S) rods and IB at L2–3 (PSO+IB+2S); (5) ACR; 6) ACR with satellite rods (ACR + 2S). A 400 N follower preload was simulated for each condition.Results:PSO condition had the largest rod stress of 286 MPa in flexion. Adding interbody support reduced the rod stress by 15%. The 4-rod constructs further reduced rod stress, with the satellite rod condition facilitating the largest reduction. The rod stress in the ACR+2S was equivalent to the PSO+2S, with 50% reduction in rod stress.Conclusion:The rod stress with an ACR was comparable to a PSO coupled with interbody support. These results suggest an ACR is a viable MIS alternative to a PSO without the need for a large posterior osteotomy.

Anterior Column Realignment (ACR) in Adult Sagittal Deformity Correction: Technique and Review of the Literature.

The anterior column realignment (ACR) procedure was retrospectively reviewed. To review surgical technique, complication avoidance, case examples, and published results on ACR. For surgical correction of sagittal imbalance, three column osteotomies (3CO) have traditionally been employed for large degrees of correction at a single segment. However, 3CO procedures are technically challenging and carry high morbidity rates. ACR was developed as a less invasive procedure for restoring segmental lordosis. The ACR surgical technique is reviewed. ACR involves either a lateral, trans-psoas or anterior retroperitoneal approach to sectioning the anterior longitudinal ligament/annulus and placing a hyperlordotic cage. ACR usually also involves a second stage posterior column osteotomy. Three case examples are presented. A review of literature on ACR papers was completed. Twelve papers met inclusion criteria. Ten to 27° of segmental lordosis were reported with use of hyperlordotic cages. 19° increase in mean intradiscal angle was reported when ACR was combined with posterior column osteotomy, 13° more than lateral lumbar interbody fusion alone without a hyperlordotic implant. Reported complication rates ranged from 18 to 47%. The most common minor complications were transient hip flexion weakness (9.3%) and transient paresthesia or dysesthesia (12%). There were few reports of major complications, such as bowel perforation (n = 1) or vascular injury (n = 1). Motor deficit was reported in 11 of 75 cases, lower than reported rates for 3CO. ACR is an emerging, less invasive technique for correction of sagittal deformity ACR has similar restorative capacity as other techniques with same or lower complication rates. 4.

Long-term radiographic outcomes of a central hook-rod construct for osteotomy closure: minimum 5-year follow-up.

Retrospective study. To evaluate long-term effectiveness of central hook-rod constructs for posterior spinal osteotomy closure. During osteotomy site closure various techniques are used, including patient positioning, rod cantilevering, extending fixation points, and compressing through pedicle fixation points. All add premature stress on fixation points and may lead to loosening/eventual fixation failure. To avoid this, we often use a central compression hook-rod construct for osteotomy closure. Fifty-six consecutive patients with fixed sagittal imbalance were treated with multilevel posterior column osteotomies (N = 19), pedicle subtraction osteotomy (N = 31), or vertebral column resection (N = 6). All 56 patients had undergone osteotomy closure using central compression hook-rod constructs and were analyzed at a follow-up of 5 years or more. Compression hooks were inserted into the fusion mass or lamina above/below the osteotomy and centrally attached to a short rod connected to pedicle screw-based rods via a cross-link. Diagnoses included sagittal imbalance associated with scoliosis (N = 39), degenerative sagittal imbalance (N = 14), ankylosing spondylitis (N = 2), and Scheuermann's kyphosis (N = 1). There were 55 revision cases and 1 primary. Radiographic/clinical analysis was performed to evaluate the efficacy/complications of this technique. Overall lumbar lordosis increased an average of 31.7° and local lordosis through the osteotomy site increased an average of 29.3°. Sagittal balance improved by an average of 92 mm. In all cases, osteotomy closures were performed without screw loosening or loss of correction intraoperatively. At a follow-up of 5 years or more, no failures of the hook-rod construct were seen, but there were 3 patients with partial implant failure; however, no symptomatic pseudarthroses at the osteotomy sites occurred. Seven patients developed pseudarthrosis below the central hook-rod construct. A central hook-rod construct is safe, controlled, and effective for applying compressive forces to close various spinal osteotomies without fixation failure or pseudarthrosis at the osteotomy site noted at a follow-up of 5 or more years. It adds fixation strength to the overall construct avoiding undue stress on pedicle screws. 3.

Radiographic outcomes of anterior column realignment for adult sagittal plane deformity: a multicenter analysis.

Anterior column reconstruction (ACR) is a minimally invasive technique for the treatment of sagittal plane deformity. ACR uses a lateral transpsoas approach with ALL release and the application of an interbody device to achieve correction. Here, we present 1-year radiographic results from a multicenter study of adult spinal deformity (ASD) patients. A multicenter database was queried from 2005 to 2013 for ASD patients treated with ACR. Demographics, surgical data, and radiographic measurements were collected and retrospectively analyzed. Radiographic time points included preoperative (pre-op), postoperative (post-op; first visit prior to 3 months), and last follow-up (last FU; minimum of 1 year). Sagittal radiographic measurements included regional lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), T1 spinopelvic inclination (T1SPi), and segmental lordosis (disc angle). Mean patient age was 67.4 years (range 46.5-80.0) and 11 patients (32.4 %) were male. Twenty patients (58.8 %) had previous lumbar surgery. All patients had a minimal of one-level ACR with ALL release (mean 1.7; range 1-4). Mean number of lateral interbody fusion (LLIF) levels without ALL release per patient was 0.7 (range 0-3). Thirty-three patients (97.1 %) received supplemental posterior fixation and 1 patient (2.9 %) had lateral fixation only. In 26 patients (76.5 %), supplemental posterior fixation was performed using an open approach, and 7 patients (20.6 %) were treated with percutaneous placement. Mean of number of levels fused was 7.1 (range 2-16). There was a significant improvement in LL (p < 0.001), PI-LL mismatch (p < 0.001), and PT (p = 0.03) from pre-op to post-op, and pre-op to last FU. There was no change in T1SPi, SS, or PI. Segmental lordosis improved at ACR levels from mean of -2.2° pre-op to -16.0° post-op (p < 0.01) and -16.3° at last FU (p < 0.001). The addition of posterior column osteotomy increased the change in segmental lordosis with ACR by 72.7 % (p < 0.001). LLIF without ALL release led to significant improvement in segmental lordosis from pre-op (-2.4°) to post-op (-7.1°; p < 0.01) but not from pre-op to last FU (-5.7°; p = 0.06). ACR successfully restores lumbar lordosis in ASD patients with sagittal imbalance. ACR results in greater segmental correction than is achieved with LLIF alone. Supplementing with posterior osteotomies allows for even greater correction. The ability to achieve the desired radiographic goals is expected to improve as technical nuances are refined and patient selection is optimized.

Finite element analysis of lordosis restoration with anterior longitudinal ligament release and lateral hyperlordotic cage placement.

Restoring sagittal alignment is an important factor in the treatment of spinal deformities. Recent investigations have determined that releasing the anterior longitudinal ligament (ALL) and placing hyperlordotic cages can increase lordosis, while minimizing need for 3 column osteotomies. The influences of parameters such as cage height and angle have not been determined. Finite element analysis was employed to assess the extent of lordosis achievable after placement of different sized lordotic cages. A 3-dimensional model of a L3-4 segment was used. Disc distraction was simulated by inserting interbody cages mid-body in the disc space. Analyses were performed in the following conditions: (1) intact, (2) ALL release, (3) ALL release + facetectomy, and (4) ALL release + posterior column osteotomy. Changes in segmental lordosis, disc height, foraminal height, and foraminal area were measured. After ALL resection and insertion of hyperlordotic cages, lordosis was increased in all cases. The lordosis achieved by the shorter cages was less due to posterior disc height maintained by the facet joints. A facetectomy increased segmental lordosis, but led to contact between the spinous processes. For some configurations, a posterior column osteotomy was required if the end goal was to match cage angle to intradiscal angle. Increased segmental lumbar lordosis is achievable with hyperlordotic cages after ALL resection. Increased cage height tended to increase the amount of lordosis achieved, although in some cases additional posterior bone resection was required to maximize lordosis. Further studies are needed to evaluate the impact on regional lumbar lordosis.

Ponte osteotomies in thoracic deformities

Thoracic hyperkyphosis is a sagittal deformity that can cause back pain and neurological impairment, leading to difficulties in maintaining a straight gaze. Sagittal thoracic malalignment has different etiologies and different corrective strategies. An adequate preoperative planning is mandatory to address correctly the surgical treatment, using an appropriate sagittal deformities classification and the rules that relate pelvic parameters to spine curvatures to determine the correction needed to restore a good sagittal alignment. Ponte osteotomies are performed in long non-angular hyperkyphotic thoracic deformities, even if idiopathic scoliosis, rigid deformities or proximal junctional kyphosis after instrumented fusions can benefit from the application of this technique that requires a mobile anterior column for the correction of the deformity. Ponte's is, together with Smith-Petersen osteotomy, a posterior column osteotomy. The magnitude of correction can reach 10° per level if intervertebral discs are still mobile.

Impact of Sagittal Spinopelvic Alignment for Clinical Outcome after Decompression Surgery for Lumbar Spinal Canal Stenosis

Health Survey Physical and Mental Component Summaries (SF-12 PCS and MCS), EuroQol-5D health survey (EQ-5D), NASS satisfaction METHODS: Analysis of 69 adult patients who underwent surgical correction of adult spinal deformity performed at a single institution. Patientreported outcomes (PROs) were assessed prospectively at baseline and 1 year postoperatively and included measures of back and leg pain on a numeric rating scale (BP-NRS and LP-NRS), Oswestry Disability Index (ODI), 12-Item Short Form Health Survey Physical and Mental Component Summaries (SF-12 PCS and MCS), and EuroQol-5D health survey (EQ-5D). Substantial clinical benefit (SCB) thresholds were determined by performing receiver operating curve (ROC) analysis using the NASS patient satisfaction score as an anchor. RESULTS: The mean age was 60 years (range 21-80). Fusion was performed over an average of 8 levels. Osteotomies performed included posterior column osteotomies in 53 patients (77%), pedicle subtraction osteotomies in 12 patients (17%), and vertebral column resection in 7 patients (10%). Significant improvements (p!0.01) were found in all PROs assessed except SF-12 MCS (mean improvement: BP-NRS [3], LP-NRS [2], ODI [14], SF-12 PCS [8], SF-12 MCS [1, p50.60] EQ-5D [0.2]. Surgery met patient expectations in 42 (61%) cases based on NASS Satisfaction Index. Substantial clinical benefit thresholds were 5.0 for BP-NRS, 2.0 for LP-NRS, 18 for ODI, 5.2 for SF-12 PCS, 3.5 for SF-12 MCS, and 0.09 for EQ-5D. There was a significant difference (p!0.01) seen in all PROs assessed for patients satisfied versus not satisfied. CONCLUSIONS: Thresholds of substantial clinical benefit following surgical procedures are important to understand, as they define the magnitude of improvement that patients recognize as significant postoperative improvement. This study provides these thresholds in adult patients undergoing scoliosis deformity surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.

Radiographical and Clinical Outcomes of Posterior Column Osteotomies in Spinal Deformity Correction

Prospectively enrolled, retrospectively analyzed case series. To evaluate a large series of pediatric patients/patients with adult spinal deformity undergoing surgery with posterior column osteotomies (PCOs). Osteotomies of the posterior column (Smith-Petersen or Ponté) are used to reduce kyphosis, increase lordosis, or increase spinal flexibility. However, little focused evidence exists regarding the efficacy and safety of this technique. A total of 128 consecutive patients underwent posterior spinal fusion with PCOs with minimum 2-year follow-up. Seventy-five were primary surgical procedures; 53 were revisions. Data were collected from hospital charts, clinic notes, radiographs, and standardized questionnaires (Scoliosis Research Society-30 and Oswestry Disability Index). A total of 128 patients aged 37.6 ± 21 years underwent 518 PCOs (mean, 4.0 ± 2.2 yr) with 14.4 ± 3 mean instrumentation levels, with 3-year (range, 2-6.8 yr) average follow-up. PCOs were used for kyphosis correction in 49%, scoliosis correction at the apex of a curve in 13%, and both in 38%. One hundred six patients had complete radiographical data available for evaluation. Mean kyphosis correction per PCO was 8.8° ± 7.2°, varying with patient age (10.2° for those younger than 21 yr vs. 7.7° for those 21 yr or older, P < 0.0001) and region of the spine: thoracolumbar (T10-L2) 11.6°, lumbar (L2-S1) 9.4°, midthoracic (T6-T10) 7.2° and proximal thoracic (T1-T6) 3.6°. With PCOs at the apex of a curve, the maximum coronal Cobb decreased from 66° ± 21° to 31° ± 14° (P < 0.0001). Average estimated blood loss was 1419 ± 887 mL, correlating with greater age (P < 0.0001) and more instrumented levels (P < 0.0001), but not with the number of PCOs (P = 0.32). Complications occurred in 31 (24.2%) patients, including 4 radiculopathies (none attributable to PCOs). Complications did not correlate with the number of PCOs (P = 0.5). Six (4.7%) patients had loss of spinal cord monitoring or a failed wake-up test that could be attributed to overcorrection with PCOs, but none had postoperative deficits. Oswestry Disability Index scores improved (34.4 ± 17 to 23.6 ± 18, P < 0.0001), as did normalized Scoliosis Research Society-30 scores (63.7 ± 13 to 76.4 ± 15, P < 0.0001). Patients in this series undergoing posterior spinal fusion with PCOs achieved overall favorable outcomes for spinal deformity correction. The number of PCOs did not correlate with increased estimated blood loss or complications. The main technical concern was overcorrection, but neurological consequences associated with overcorrection were identified by intraoperative spinal cord monitoring and wake-up tests, and no patients experienced permanent neurological deficits related to PCOs. 4.