PLF Versus PLIF and the Fate of L5-S1: Analysis of Operative Nonunion Rates Among 3065 Patients with Lumbar Fusions from a Regional Spine Registry.

STUDY DESIGN: A retrospective cohort study with chart review. OBJECTIVE: The aim of this study was to compare the reoperation rates for symptomatic nonunions (operative nonunion rates) between posterolateral fusions with pedicle screws (PLFs) and posterior interbody fusion with pedicle screws (PLIFs). SUMMARY OF BACKGROUND DATA: Although radiographic nonunions in PLFs and PLIFs are well documented in the literature, there is no consensus on which technique has lower nonunions. Since some radiographic nonunions may be asymptomatic, a more clinically useful measure is operative nonunions, of which there is minimal research. METHODS: A retrospective cohort study, using data from the Kaiser Permanente Spine Registry, identified adult patients (≥18 years' old) who had elective single and multilevel PLFs and PLIFs. Descriptive statistics and 2-year incidence rates for operative nonunions were calculated by fusion-level (1-3), fusion type (PLF vs. PLIF), and levels fused (L3 to S1). Time-dependent multivariable Cox-Proportional Hazards regression was used to evaluate nonunion reoperation rates with adjustment for covariates. RESULTS: The cohort consisted of 3065 patients with PLFs (71.6%) and PLIFs (28.4%). Average age was 65.0 ±â€Š11.7, average follow-up time was 4.8 ±â€Š3.1 years, and average time to operative nonunion was 1.6 (±1.3) years. Single and multilevel incidence rates for nonunions after PLF versus PLIF were similar except for three-level fusions (2.9% [95% confidence interval, CI = 1.0-6.7] vs. 7.1% [95% CI = 0.2-33.9]). In adjusted models, there was no difference in risk of operative nonunions in PLIF compared to PLF (hazard ratio [HR]: 0.8, 95% CI = 0.4-1.6); however, patients with L5-S1 constructs with PLFs had 2.8 times the risk of operative nonunion compared to PLIFs (PLF: HR = 2.8, 95% CI = 1.3-6.2; PLIF: HR = 1.5, 95% CI = 0.4-5.1). CONCLUSION: In a large cohort of patients with >4 years of follow-up, we found no difference in operative nonunions between PLF and PLIF except for constructs that included L5-S1 in which the risk of nonunion was limited to PLF patients.Level of Evidence: 3.

Use of an inertial measurement unit sensor in pedicle screw placement improves trajectory accuracy.

Ascertaining the accuracy of the pedicle screw (PS) trajectories is important as PS malpositioning can cause critical complications. We aimed to determine the angle range over which estimation is unreliable; build a low-cost PS placement support system that uses an inertial measurement unit (IMU) to enable the monitoring of surgical tools and PS trajectories, and determine the situations where IMU support would be most beneficial. In PS insertion experiments, we used cadaver samples that included lumbar porcine spines. Computed tomography images obtained before and after PS insertion were viewed. Offsets between the planned and implanted PS trajectories in the freehand and IMU-assisted groups were analyzed. The PS cortical bone breaches were classified according to the Gertzbein and Robbins criteria (GRC). Added head-down tilted sample experiments were repeated wherein we expected a decreased rostro-caudal rotational accuracy of the PS according to the angle estimation ability results. Evaluation of the PS trajectory accuracy revealed no significant advantage of IMU-assisted rostro-caudal rotational accuracy versus freehand accuracy. According to the GRC, IMU assistance significantly increased the rate of clinically acceptable PS positions (RoCA) than the freehand technique. In the head-down tilted sample experiments, IMU assist provided increased accuracies with both rostro-caudal and medial rotational techniques when compared with the freehand technique. In the freehand group, RoCA was significantly decreased in samples with rostral tilting relative to that in the samples without. However, In the IMU-assisted group, no significant difference in RoCA between the samples with and without head-down tilting was observed. Even when the planned PS medial and/or rostro-caudal rotational angle was relatively large and difficult to reproduce manually, IMU-support helped maintain the PS trajectory accuracy and positioning safety. IMU assist in PS placement was more beneficial, especially for larger rostro-caudal and/or medial rotational pedicle angles.

Restoration of Thoracic Kyphosis in Adolescent Idiopathic Scoliosis Over a Twenty-year Period: Are We Getting Better?

STUDY DESIGN: A multicenter, prospectively collected database of 20 years of operatively treated adolescent idiopathic scoliosis (AIS) was utilized to retrospectively examine pre- and postoperative thoracic kyphosis at 2-year follow-up. OBJECTIVE: To determine if the adoption of advanced three-dimensional correction techniques has led to improved thoracic kyphosis correction in AIS. SUMMARY OF BACKGROUND DATA: Over the past 20 years, there has been an evolution of operative treatment for AIS, with more emphasis on sagittal and axial planes. Thoracic hypokyphosis was well treated with an anterior approach, but this was not addressed sufficiently in early posterior approaches. We hypothesized that patients with preoperative thoracic hypokyphosis prior to 2000 would have superior thoracic kyphosis restoration, but the learning curve with pedicle screws would reflect initially inferior restoration and eventual improvement. METHODS: From 1995 to 2015, 1063 patients with preoperative thoracic hypokyphosis (<10°) were identified. A validated formula for assessing three-dimensional sagittal alignment using two-dimensional kyphosis and thoracic Cobb angle was applied. Patients were divided into 1995-2000 (Period 1, primarily anterior), 2001-2009 (Period 2, early thoracic pedicle screws), and 2010-2015 (Period 3, modern posterior) cohorts. Two-way repeated measures analysis of variance and post-hoc Bonferroni corrections were utilized with P < 0.05 considered significant. RESULTS: Significant differences were demonstrated. Period 1 had excellent restoration of thoracic kyphosis, which worsened in Period 2 and improved to near Period 1 levels during Period 3. Period 3 had superior thoracic kyphosis restoration compared with Period 2. CONCLUSION: Although the shift from anterior to posterior approaches in AIS was initially associated with worse thoracic kyphosis restoration, this improved with time. The proportion of patients restored to >20° kyphosis with a contemporary posterior approach has steadily improved to that of the era when anterior approaches were more common. LEVEL OF EVIDENCE: 3.

Clinical and Radiological Outcomes of Less Invasive Temporary Internal Distraction Followed by Staged Pedicle Screw Instrumentation in Adolescents with Severe Idiopathic Scoliosis at 2-Year Minimum Follow-Up.

OBJECTIVES: Temporary placement of an internal distraction rod is one of the surgical options in the treatment of severe scoliosis to avoid preoperative halo traction or vertebral column resection. This technique can be applied in a single session or staged. The aim of our study was to report the outcomes of less-invasive temporary internal distraction (LI-TID) in the surgical treatment of adolescents with severe idiopathic scoliosis (IS). METHODS: We performed a single-center, retrospective study of 22 adolescents (19 girls; mean age, 14.8 ± 2.0 years) with severe IS (major curve, ≥90°) who had undergone LI-TID, followed by staged pedicle screw instrumentation, with a minimum of 2 years of follow-up available. The demographic data, radiographic outcomes, pulmonary function test results, perioperative data, revised 22-item Scoliosis Research Society Outcomes questionnaire results, complications, and neuromonitoring data were collected. RESULTS: The average major curve was 120° (range, 90°-160°) preoperatively and 59° (range, 29°-69°) at the final follow-up examination. Thoracic kyphosis (T5-T12) had improved from an average of 80° preoperatively to 33° postoperatively (range, 22°-69°), and the spinal height (T1-S1) had increased from 332 mm (range, 198-432 mm) preoperatively to 405 mm (range, 258-495 mm) at the final follow-up visit. Of the 22 patients, 5 (22.7%) had experienced an intraoperative neuromonitoring change without postoperative neurologic deficits, and 2 had developed superior mesenteric artery syndrome, with resolution after conservative treatment. The mean percentage of the predicted forced vital capacity had improved from 44.5% ± 11.3% to 66.5 ± 10.8 at final follow-up (P < 0.05). The total questionnaire score had improved significantly from 2.9 ± 0.61 to 4.1 ± 0.44 (P < 0.05). CONCLUSION: The results from the present study have shown that staged LI-TID, followed by pedicle screw instrumentation, is safe and effective in adolescents with severe IS, with improvements in spinal deformity, pulmonary function, and health-related quality of life.

Minimally invasive spinal fixation in an aging population with osteoporosis: clinical and radiological outcomes and safety of expandable screws versus fenestrated screws augmented with polymethylmethacrylate.

OBJECTIVE: The goal of this study was to compare the clinical and radiological outcomes between fenestrated pedicle screws augmented with cement and expandable pedicle screws in percutaneous vertebral fixation surgical procedures for the treatment of degenerative and traumatic spinal diseases in aging patients with osteoporosis. METHODS: This was a prospective, single-center study. Twenty patients each in the expandable and cement-augmented screw groups were recruited. Clinical outcomes included visual analog scale (VAS), Oswestry Disability Index (ODI), and satisfaction rates. Radiographic outcomes comprised radiological measurements on the vertebral motion segment of the treated levels. Intraoperative data including complications were collected. All patients completed the clinical and radiological outcomes. Outcomes were compared preoperatively and postoperatively. RESULTS: An average shorter operative time was found in procedures in which expandable screws were used versus those in which cement-augmented screws were used (p < 0.001). No differences resulted in perioperative blood loss between the 2 groups. VAS and ODI scores were significantly improved in both groups after surgery. There was no significant difference between the 2 groups with respect to baseline VAS or ODI scores. The satisfaction rate of both groups was more than 85%. Radiographic outcomes also showed no significant difference in segment stability between the 2 groups. No major complications after surgery were seen. There were 4 cases (20%) of approach-related complications, all in fenestrated screw procedures in which asymptomatic cement extravasations were observed. In 1 case the authors detected a radiologically evident osteolysis around a cement-augmented screw 36 months after surgery. In another case they identified a minor loosening of an expandable screw causing local back discomfort at the 3-year follow-up. CONCLUSIONS: Expandable pedicle screws and polymethylmethacrylate augmentation of fenestrated screws are both safe and effective techniques to increase the pullout strength of screws placed in osteoporotic spine. In this series, clinical and radiological outcomes were equivalent between the 2 groups. To the authors' knowledge, this is the first report comparing the cement augmentation technique versus expandable screws in the treatment of aging patients with osteoporosis.

A Clinical Application Study of Mixed Reality Technology Assisted Lumbar Pedicle Screws Implantation.

BACKGROUND This was a prospective comparative study of mixed reality (MR) technology assisted lumbar pedicle screws placement and traditional lumbar pedicle screws placement. MATERIAL AND METHODS Fifty cases of lumbar pedicle screws placement were randomly divided into 2 groups: 25 cases with MR technology in group A, and 25 cases without MR technology in group B. All patients had their scores on the Oswestry disability index (ODI) of low back pain and the visual analog scale (VAS) of the affected lower limb recorded at pre-operation. Blood loss, operative duration, success rate of first penetration by tap, and number of times C-arm fluoroscopy was performed were recorded at intraoperation. The postoperative drainage was recorded. The ODI of low back pain and VAS of the affected lower limb were recorded at 1, 3, and 6 months after operation. RESULTS Group A had less bleeding, shorter operation time, higher success rate of first penetration by tap, and fewer times using C-arm fluoroscopy at intraoperation (P<0.05). There was significant difference in ODI scores and VAS scores at 1 mouth after operation (P<0.05). The postoperative drainage of group A was less than group B (P<0.05). The implantation accuracy of group A was higher than group B (P<0.05). The postoperative recovery rate of low back pain of group A was faster than group B (P<0.05). CONCLUSIONS The safety of spinal surgery and implantation accuracy of pedicle screw fixation system could be increased by MR technology.

Biomechanical evaluation of strategies for adjacent segment disease after lateral lumbar interbody fusion: is the extension of pedicle screws necessary?

BACKGROUND: Adjacent segment disease (ASD) is a well-known complication after interbody fusion. Pedicle screw-rod revision possesses sufficient strength and rigidity. However, is a surgical segment with rigid fixation necessary for ASD reoperation? This study aimed to investigate the biomechanical effect of different instrumentation on lateral lumbar interbody fusion (LLIF) for ASD treatment. METHODS: A validated L2~5 finite element (FE) model was modified for simulation. ASD was considered the level cranial to the upper-instrumented segment (L3/4). Bone graft fusion in LLIF with bilateral pedicle screw (BPS) fixation occurred at L4/5. The ASD segment for each group underwent a) LLIF + posterior extension of BPS, b) PLIF + posterior extension of BPS, c) LLIF + lateral screw, and d) stand-alone LLIF. The L3/4 range of motion (ROM), interbody cage stress and strain, screw-bone interface stress, cage-endplate interface stress, and L2/3 nucleus pulposus of intradiscal pressure (NP-IDP) analysis were calculated for comparisons among the four models. RESULTS: All reconstructive models displayed decreased motion at L3/4. Under each loading condition, the difference was not significant between models a and b, which provided the maximum ROM reduction (73.8 to 97.7% and 68.3 to 98.4%, respectively). Model c also provided a significant ROM reduction (64.9 to 77.5%). Model d provided a minimal restriction of the ROM (18.3 to 90.1%), which exceeded that of model a by 13.1 times for flexion-extension, 10.3 times for lateral bending and 4.8 times for rotation. Model b generated greater cage stress than other models, particularly for flexion. The maximum displacement of the cage and the peak stress of the cage-endplate interface were found to be the highest in model d under all loading conditions. For the screw-bone interface, the stress was much greater with lateral instrumentation than with posterior instrumentation. CONCLUSIONS: Stand-alone LLIF is likely to have limited stability, particularly for lateral bending and axial rotation. Posterior extension of BPS can provide reliable stability and excellent protective effects on instrumentation and endplates. However, LLIF with the use of an in situ screw may be an alternative for ASD reoperation.

More Than 10-year Follow-up After Laminoplasty and Pedicle Screw Fixation for Cervical Myelopathy Associated With Athetoid Cerebral Palsy.

STUDY DESIGN: Retrospective case series. OBJECTIVE: The aim of this study was to investigate the clinical outcomes >10 years following laminoplasty and pedicle screw fixation for cervical myelopathy associated with athetoid cerebral palsy (CP). SUMMARY OF BACKGROUND DATA: Surgery for cervical myelopathy associated with CP remains a challenge because of perioperative instrumentation failure and adjacent segment problems due to patients' repetitive involuntary neck movements with deformity of the cervical spine. METHODS: A single-center series of 14 patients were reviewed. The patients comprised seven women and seven men with a mean age of 52 years at the time of surgery. The mean follow-up period was 12.5 years. The Barthel index (BI), which shows independence in activities of daily life, and Japanese Orthopaedic Association (JOA) score were assessed. Radiographic evaluation included changes of the C2-C7 angle in the sagittal plane, fusion rate, adjacent segment degeneration, and instrument failure. RESULTS: The 10-year BI and JOA score significantly improved at 36% and 31%, respectively. The preoperative Cobb angle of the sagittal plane from C2-C7 measured 11.9° of kyphosis, which improved to 0.8° of lordosis. In the radiographic analysis, 35% (proximal) and 21% (distal) of the adjacent segment showed progression in degeneration of more than one grade after 10 years. More than 90% of the patients who underwent magnetic resonance imaging showed progressive disc degeneration on either side after 10 years. Autofusion inside the disc or anterior vertebral bony bridging was observed in 86% of intervertebral levels without anterior procedures. CONCLUSION: The procedure showed favorable initial stability and maintained favorable clinical outcomes in patients with CP. More than 90% of the patients showed disc degeneration on either side. The rate of proximal adjacent segment degeneration was higher than that of distal segments with or without symptoms at the >10-year follow-up. LEVEL OF EVIDENCE: 4.

The Effect of Paraspinal Muscle Degeneration on Distal Pedicle Screw Loosening Following Corrective Surgery for Degenerative Lumbar Scoliosis.

MINI: A total of 137 degenerative lumbar scoliosis patients were divided into two groups. In group A (six or more fused levels), mean rFCSA of erector spinae <0.71 was an independent risk factor of LIV screw loosening. In Group B (four or five fused levels), paraspinal muscle degeneration had no influence on LIV screw loosening. STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study was to evaluate the effect of degeneration of paraspinal muscles, including psoas muscles, erector spinae muscles, and multifidus muscles on pedicle screw loosening at lower instrumented vertebra (LIV) following corrective surgery for degenerative lumbar scoliosis (DLS). SUMMARY OF BACKGROUND DATA: The relation between paraspinal muscles and pedicle screw loosening in DLS patients has not been reported. METHODS: A total of 137 DLS patients underwent corrective surgery with at least 1-year follow-up were included. The patients were divided into two groups: Group A (68 patients) had six or more fused levels and Group B (69 patients) had four or five fused levels. Muscular parameters, including relative cross-sectional area (rCSA) and muscle-fat index (MFI), were measured on preoperative magnetic resonance imaging. rCSA and MFI were measured for both gross muscle (G) and functional muscle (F) as rGCSA, rFCSA, GMFI, and FMFI. Muscle ratio was calculated as rFCSA/rGCSA. Pedicle screw loosening was assessed on spine radiographs or CT at final follow-up. Clinical and radiological screw loosening were classified according to clinical significance. RESULTS: LIV screw loosening occurred in 77 patients at final follow-up. In Group A, patients with LIV screw loosening had significantly higher FMFI of psoas muscles and lower rFCSA and rGCSA of erector spinae. Logistic regression revealed that mean rFCSA of erector spinae <0.71 (odds ratio = 5.0, 95% confidence interval = 1.5-16.4) was an independent risk factor of LIV screw loosening. Mean muscle ratio of erector spinae was significantly lower in patients with clinical screw loosening compared with radiological screw loosening in univariate analysis. In Group B, all muscular parameters showed no significant difference. CONCLUSION: Degeneration of paraspinal muscles, especially psoas muscles and erector spinae, affected LIV screw loosening in six or more level fusion in corrective surgery for DLS, whereas the four- or five-level fusion had no this influence. LEVEL OF EVIDENCE: 3.

A retrospective study. The aim of this study was to evaluate the effect of degeneration of paraspinal muscles, including psoas muscles, erector spinae muscles, and multifidus muscles on pedicle screw loosening at lower instrumented vertebra (LIV) following corrective surgery for degenerative lumbar scoliosis (DLS). The relation between paraspinal muscles and pedicle screw loosening in DLS patients has not been reported. A total of 137 DLS patients underwent corrective surgery with at least 1-year follow-up were included. The patients were divided into two groups: Group A (68 patients) had six or more fused levels and Group B (69 patients) had four or five fused levels. Muscular parameters, including relative cross-sectional area (rCSA) and muscle-fat index (MFI), were measured on preoperative magnetic resonance imaging. rCSA and MFI were measured for both gross muscle (G) and functional muscle (F) as rGCSA, rFCSA, GMFI, and FMFI. Muscle ratio was calculated as rFCSA/rGCSA. Pedicle screw loosening was assessed on spine radiographs or CT at final follow-up. Clinical and radiological screw loosening were classified according to clinical significance. LIV screw loosening occurred in 77 patients at final follow-up. In Group A, patients with LIV screw loosening had significantly higher FMFI of psoas muscles and lower rFCSA and rGCSA of erector spinae. Logistic regression revealed that mean rFCSA of erector spinae <0.71 (odds ratio = 5.0, 95% confidence interval = 1.5­16.4) was an independent risk factor of LIV screw loosening. Mean muscle ratio of erector spinae was significantly lower in patients with clinical screw loosening compared with radiological screw loosening in univariate analysis. In Group B, all muscular parameters showed no significant difference. Degeneration of paraspinal muscles, especially psoas muscles and erector spinae, affected LIV screw loosening in six or more level fusion in corrective surgery for DLS, whereas the four- or five-level fusion had no this influence. Level of Evidence: 3.

Comparison of outcomes between cortical screws and traditional pedicle screws for lumbar interbody fusion: a systematic review and meta-analysis.

PURPOSE: The clinical outcomes of using a cortical screw (CS) for lumbar interbody fusion were evaluated by comparison with conventional pedicle screw (PS) fixation. METHODS: All of the comparative studies published in the PubMed, Cochrane Library, MEDLINE, Web of Science, and EMBASE databases recently as 18 March 2019, were included. All outcomes were analyzed by using Review Manager 5.3. RESULTS: Twelve studies were included with a total of 835 patients, and two of the studies were randomized controlled trials. The outcomes of the meta-analysis indicated that the use of CS fixation for lumbar interbody fusion was better than conventional PS fixation in regard to operating time (p = 0.02), intraoperative blood loss (p < 0.00001), length of stay (p = 0.02), incidence of complications (p = 0.02), adjacent segmental disease (ASD) incidence (p = 0.03), and Oswestry Disability Index (ODI) (p = 0.03). However, there were no statistically significant differences in the back and leg pain visual analog scale (VAS), Japanese Orthopaedic Association (JOA) scale, and intervertebral fusion rate (all p > 0.05) between the CS fixation group and the PS fixation group. CONCLUSIONS: Based on this systematic review and meta-analysis, our outcomes indicated that both CS and conventional PS can result in good postoperative outcomes in lumbar interbody fusion. No significant differences were found in the back and leg pain VAS, JOA scale, and intervertebral fusion rate. However, CS fixation is superior to PS fixation in the following measures: operating time, intraoperative blood loss, length of stay, incidence of complications, ASD incidence, and ODI. TRIAL REGISTRATION: PROSPERO registration number is CRD 42019132226 .

Idiopathic Scoliosis in Children and Adolescents: Emerging Techniques in Surgical Treatment.

BACKGROUND: Idiopathic scoliosis is the most common spinal disorder in the pediatric population. The goals of treatment for pediatric idiopathic scoliosis are to correct deformity, prevent curve progression, restore trunk symmetry and balance, and minimize pain and morbidity. Surgical treatment has advanced significantly, from the advent of segmental pedicle screw instrumentation several decades ago to the recent development of robotic-assisted surgery and growth-modulating fusionless surgery. The objective of the present study was to review the reported data on emerging techniques in the surgical treatment of idiopathic scoliosis in children and adolescents. METHODS: The PubMed and Google Scholar electronic databases were used to identify studies that had examined new emerging techniques in the surgical treatment of idiopathic scoliosis in children and adolescents. RESULTS: Major developments in the surgical techniques for pediatric idiopathic scoliosis have included robotic-assisted pedicle screw placement, vertebral body stapling, vertebral body tethering, magnetically controlled growing rods, ApiFix (not currently approved for use in the United States by the Food and Drug Administration), and sublaminar polyester bands. Such growth-modulating fusionless surgical techniques have received increasing attention in recent years, especially for the younger pediatric scoliosis population with significant growth potential remaining. CONCLUSIONS: Various emerging techniques in the surgical treatment of idiopathic scoliosis in children and adolescents have demonstrated promising results in the reported data thus far. However, longer term prospective studies with larger cohorts are necessary to better evaluate their safety and efficacy.

Augmented pedicle trajectory applied on the osteoporotic spine with lumbar degenerative disease: mid-term outcome.

PURPOSE: To compare the safety and efficiency of cement-augmented pedicle screw with traditional pedicle screw technique applied on the patients in the osteoporotic spine with lumbar degenerative diseases. METHODS: Fifty-six patients followed up at least 2 years were enrolled in our institute with retrospectively reviewed from January 2009 to June 2014, diagnosed as lumbar spondylolisthesis, or lumbar stenosis, with T score ≤- 2.5 SD of BMD, and received less than three-segment PLIF or TLIF. All patients were divided into 2 groups: 28 (2 males, 26 females) in polymethylmethacrylate-augmented pedicle screw group (PSA) group, the other 28 (3 males, 25 females) in traditional pedicle screw group (TPS). Surgical data including the operation time, intra-operative blood loss, hospitalization day and surgical complications were recorded, as well as the radiological parameters measured from the postoperative X-rays and CT scans containing the rates of fusion, screw loosening, and cage subsidence incidence. In addition, the visual analog scores (VAS) and Oswestry Disability Index (ODI) were evaluated preoperatively and postoperatively. RESULTS: The average follow-up period was 34.32 months (ranging from 24 months to 51 months). Compared with PSA group, operation time and average hospital stay in the TPS group decreased significantly (P < 0.05). While no statistical difference for blood loss between 2 groups (P > 0.05). At 2 years postoperation, from CT-scans, 2/172 screws loosening and 1/56 segment non-union occurred in PSA group, with significantly lower incidence than those in TPS group (8/152 screws loosening and 6/50 segments non-union occurred, P < 0.05). Regarding the cage subsidence, 24 segments found height loss (5.30 ± 1.92 mm) in PSA group without difference compared with that of 19 segments (4.78 ± 1.37 mm) in TPS group (P > 0.05). Besides, the number and the location of cages and the leakage of the cement were found out little related with the subsidence in the PSA group (P > 0.05). After surgeries, VAS and ODI at 1 month, 6 months, 12 months, and last follow-up improved significantly in two groups (P < 0.05). There were no significant differences in VAS and ODI preoperatively and postoperatively between 2 groups (P > 0.05). In addition, eight patients with asymptomatic trajectory PMMA leakages were detected. CONCLUSION: Cement-augmented pedicle screw technique is effective and safe in the osteoporotic spine with lumbar degenerative diseases, with better fusion rates and less screw loosening incidence. There is no difference in the fusion rate and loosening rate between the two groups in the single segment patients; however, there are better fusion rate and lower pedicle screw loosening rate of the PSA group in the double or multiple group patients.

Clinical and radiological outcomes of the multilevel Ponte osteotomy with posterior selective segmental pedicle screw constructs to treat adolescent thoracic idiopathic scoliosis.

BACKGROUND: To compare the clinical and radiological outcomes of the surgical correction of Lenke type 1 to 4 scoliosis by using a multilevel Ponte osteotomy procedure with posterior selective segmental pedicle screw constructs or posterior release and selective segmental pedicle screw constructs only in patients with adolescent thoracic idiopathic scoliosis. METHODS: Retrospective analysis of 65 patients, 32 treated with the multilevel Ponte procedure (Group A) and 33 with posterior soft tissue release only (Group B). The groups were compared with regard to the change in spinal alignment from preoperative to postoperative assessment and over the follow-up period. RESULTS: A correction rate of the main thoracic curve of 63.9 ± 4.5% was obtained for group A and 65.2 ± 2.4% for group B (P = 0.17). However, the Cincinnati correction index was greater for group A (1.8 ± 0.3) than that for group B (1.4 ± 0.2, P < 0.001), with a smaller change in angle over the period from 1 week postoperatively to the 2-year follow-up (P < 0.05). The operative time, volume of blood loss, and volume of transfusion were greater for group A than for group B (P < 0.05). CONCLUSION: The multilevel Ponte osteotomy procedure, with posterior selective segmental pedicle screw constructs, improves the Cincinnati correction index and restores the thoracic kyphosis in patients with adolescent thoracic idiopathic scoliosis.

Radiographic outcomes of transosseous intradiscal screw fixation in lumbar reconstruction-Imaging results of an experience with an alternative in fixation of the unexpectedly osteopenic spine.

OBJECTIVE: To present the results of a new alternative in the technique lumbar pedicle screw reconstruction in osteopenic bone. Pedicle screw fixation is compromised in osteopenic bone and adjunct fixation commonly requires incremental technology that can increase cost and risk, and which may not commonly be available. Readily available low cost techniques are desirable. PATIENTS AND METHODS: This is a retrospective review of a prospectively accumulated case series of all patients presenting to the senior author's (DAB) practice for elective lumbar reconstruction at a tertiary spine referral center. All consecutive patients treated by the senior author 2002-2012 who were unexpectedly found to be severely osteopenic at surgery are reported. RESULTS: In seventy-four cases with imaging and clinical information available at an average of five years after surgery there was no screw lucency or accelerated disc degeneration observed despite these screws purposefully projecting into the suprajacent disc space within the limits of the construct. No patient had presented for instrumentation-related revision surgery of any sort. CONCLUSION: Transosseous intradiscal screw fixation is a potentially viable alternative in surgical stabilization of the unexpectedly osteopenic lumbar spine.

How Many Screws Are Necessary to Be Considered an Experienced Surgeon for Freehand Placement of Thoracolumbar Pedicle Screws?: Analysis Using the Cumulative Summation Test for Learning Curve.

OBJECTIVE: To determine the amount of screws needed to achieve an adequate skill level for pedicle screw placement (PSP) via the freehand technique in the nondeformed thoracolumbar spine using the cumulative summation test for learning curve (LC-CUSUM) analysis. METHODS: This study includes the first 85 patients who underwent pedicle screw installation in the thoracic and lumbar spine by a single orthopedic surgeon. The surgeon had 1 years' experience of fellowship training in a tertiary teaching hospital. The learning curve of freehand PSP was investigated using the LC-CUSUM analysis. Procedure success was defined as acceptable accuracy of PSP, which was divided into group 1 (the screw breaches the pedicle's cortex by less than 2 mm) and group 2 (the screw is completely within the pedicle). RESULTS: A total of 52 cases and 313 pedicle screws were included and analyzed in this study. The LC-CUSUM analysis signaled competency for freehand PSP at the 115th pedicle screw (17th case) in group 1 and at the 312th pedicle screw (52nd case) in group 2. This means that a trainee with no experience with freehand PSP reached an adequate accuracy level of PSP with less than 2 mm pedicle breaches at the 115th screw and completely within the pedicle at the 312th screw. There were no major complications, such as neurovascular injury, and life-threatening complications. CONCLUSIONS: In this study, the learning curve analysis demonstrated that a substantial learning period may be necessary before an adequate level of performance is achieved for freehand PSP in the nondeformed thoracolumbar spine.

The use of the DTO™ hybrid dynamic device: a clinical outcome- and radiological-based prospective clinical trial.

BACKGROUND: The purpose of this study was to assess the radiological and clinical outcome parameters following lumbar hybrid dynamic instrumentation with the focus on the adjacent segment degeneration (ASD) and adjacent segment disease (ASDi). METHODS: In this prospective trial all patients presenting with degenerative changes to the lumbar spine have been included. Precondition was a stable adjacent level with/without degenerative alteration. The elected patients underwent a standardised fusion procedure with hybrid instrumentation (DTO™, Zimmer Spine Inc., Denver, USA). Patients' demographics have been documented and the follow-up visits were conducted after 6 weeks, and then stepwise after 6 up to 48 months. Each follow-up visit included assessment of quality of life and pain using specific questionnaires (COMI, SF-36, ODI) and the radiological evaluation with focus on the adjacent level alterations. RESULTS: At a mean follow up of 24 months an incidence of ASD with 10.91% and for ASDi with 18.18% has been observed. In 9% a conversion to standardised fusion was needed. There was a high rate of mechanical complication: (1) screw loosening (52.73%), (2) pedicle screw breakage (10.91%), and (3) rod breakage (3.64%) after a follow up of a maximum of 60 months. There were no significant difference of COMI, ODI and SF-36(v2) in comparison to all groups but all 55 patients showed a clinical improvement over the time. CONCLUSION: The dynamic hybrid DTO™ device is comparable to the long-term results after standardised fusion procedure, while a high rate of mechanical complication decreased the initial benefit. TRIAL REGISTRATION: This trial was registered at the ClinicalTrials Register ( #NCT03404232 , 2018/01/18, registered retrospectively).

Pedicle Screw with Cement Augmentation in Unilateral Transforaminal Lumbar Interbody Fusion: A 2-Year Follow-Up Study.

OBJECTIVE: To evaluate safety and efficacy of pedicle screw with polymethyl methacrylate (PMMA) augmentation in unilateral transforaminal lumbar interbody fusion (uTLIF) in osteoporotic patients. METHODS: We randomly divided 50 osteoporotic patients with degenerative lumbar diseases diagnosed between February 2014 and November 2015 into 2 groups. One group underwent standard uTLIF, and the other group underwent uTLIF with PMMA augmentation. All patients were scheduled to attend a series of regular follow-up evaluations. Oswestry Disability Index, Japanese Orthopaedic Association score, visual analog scale score, lumbar lordotic angle, segmental lordotic angle, and disc space height (DSH) at each follow-up were collected and analyzed. RESULTS: The 2-year follow-up was completed by 24 patients in the uTLIF group and 23 patients in the PMMA group. Oswestry Disability Index, Japanese Orthopaedic Association score, and visual analog scale score showed significant improvements after surgery in both groups, with no significant difference between groups. DSH in the uTLIF group was 8.7 ± 2.3 mm and in the PMMA group was 10.7 ± 1.6 mm. Fusion rate in the uTLIF group was 19/24 and in the PMMA group was 21/23. DSH and fusion rate in the PMMA group were higher than those in the uTLIF group. No severe complications were observed after PMMA injection. CONCLUSIONS: Pedicle screw with PMMA augmentation can increase fixation stability and reduce DSH loss in uTLIF. Moreover, PMMA in the vertebral body did not impede the interbody fusion ability in uTLIF.

Lumbar Interbody Fusion: A Historical Overview and a Future Perspective.

: In this historical study we present an overview of lumbar interbody fusion surgery, which is one of the most commonly performed instrumented spinal fusion surgeries. The present article focuses on the history of lumbar interbody fusion surgery, starting from the foundation which was laid in the 19th and 20th century until today. The development of material and techniques evolved from simple wiring to the combination of transforaminal interbody fusion with polyether ether ketone cages and pedicle screw fixation with poly axial screws. The possibilities of instrumented spinal fusion grew during the past 100 years, and a considerable increase in instrumented spinal surgery was seen over the past decades. Today, gain lies in perfection of techniques and deliberate indication and development of guidelines. Therefore, more standardized studies on instrumented spinal surgery are needed to be done and techniques should be personalized on the patients' specific needs. LEVEL OF EVIDENCE: N/A.

Comparison of Outcomes Between C1-C2 Screw-Hook Fixation and C1-C2 Screw-Rod Fixation for Treating Reducible Atlantoaxial Dislocation.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To compare the outcomes of C1-C2 transarticular screw with C1 laminar hook (TAS + C1H) fixation and C1 trans-arch lateral mass screw with C2 pedicle screw (C1TLMS + C2PS) fixation in the treatment of reducible atlantoaxial dislocation (AAD). SUMMARY OF BACKGROUND DATA: TAS + C1H is comparable to TAS with posterior wiring techniques and superior to C1 lateral mass screw combined with C2 pedicle screw (C1LMS + C2PS) in biomechanics. There were, however, few studies analyzing the differences in outcomes between TAS + C1H technique and modified C1LMS + C2PS technique (C1TLMS + C2PS) for treating AAD. METHODS: Data of 30 patients with reducible AAD treated by TAS + C1H fixation and another 30 cases treated by C1TLMS + C2PS fixation were retrospectively analyzed. Bone fusion time was recorded. The outcomes evaluated by American Spinal Injury Association impairment scale, visual analog scale score for neck pain, neck stiffness (none/mild/severe), patient satisfaction, and Neck Disability Index (NDI) were compared between two groups. RESULTS: There were no complications related to the surgical approach and instrumentation in either group. At the final follow-up, bone graft fusion rates were 100% in both the TAS + C1H fixation group and the C1TLMS + C2PS fixation group (P > 0.05). The neurological status evaluated by American Spinal Injury Association impairment scale were greatly improved in both screw-hook group (P < 0.001) and screw-rod group (P < 0.001), but with no significant differences between groups (P > 0.05). There were no significant differences between two groups in visual analog scale score for neck pain, neck stiffness, patient satisfaction, or Neck Disability Index (all P > 0.05). CONCLUSION: C1TLMS + C2PS fixation was comparable to TAS + C1H fixation in fusion rate and functional outcomes for treating reducible AAD. To reduce the risk of vertebral artery injury, computed tomography scan, and reconstruction should be done to analyze vertebral artery course and C1-C2 anatomic structures before operation. LEVEL OF EVIDENCE: 3.