All-pedicle Screw Research Articles

Three-dimensional deformity correction in adolescent idiopathic scoliosis patients: what are the benefits of hybrid apical sublaminar bands versus all-pedicle screws?

The amount of three-dimensional (3D) correction with apical sublaminar band (hybrid-SLB) technique has not been compared to all-pedicle screw instrumentation for adolescent idiopathic scoliosis (AIS) using detailed axial correction metrics or comparable rod types. Our purpose is to compare 3D improvement in AIS deformities following posterior spinal instrumentation and fusion (PSIF) with hybrid-SLB and segmental correction to all-pedicle screw correction. Patients ages 10-18 years with AIS who underwent PSIF between 2015 and 2022 and had preoperative and postoperative EOS imaging were included. Electronic medical records were reviewed for demographic, Lenke classification, operative technique, and 3D EOS data. Average changes in major and minor Cobb angle, axial rotation, thoracic kyphosis, and lumbar lordosis were compared. Ninety-five patients met inclusion criteria with 55 in the hybrid-SLB group (mean age 14.9 ± 1.9 years) and 40 in all-pedicle screw (mean age 14.7 ± 2.1 years). While all-pedicle screw demonstrated greater correction of major (45.7 ± 13.4 vs 37.9 ± 14.3 degrees; P = 0.008) and minor (28.7 ± 13.1 vs 17.8 ± 12.5 degrees; P = 0.001) Cobb angles, hybrid-SLB showed greater increase in T4-T12 kyphosis (13.3 ± 15.3 vs 5.6 ± 13.5 degrees; P = 0.01). Correction of T1-T12 kyphosis, axial rotation, and lumbar lordosis was similar between groups. 3D EOS analysis of AIS patients before and after PSIF revealed that all-pedicle screw constructs had greater overall coronal plane correction and hybrid-SLB had greater thoracic sagittal plane correction. Axial corrective abilities were similar. Hybrid-SLB may have advantages for correction of thoracic lordosis or hypokyphosis. Level of evidence: Level III, retrospective cohort study.

Topping-Off a Long Thoracic Stabilization With Semi-Rigid Constructs May Have Favorable Biomechanical Effects to Prevent Proximal Junctional Kyphosis: A Biomechanical Comparison.

In-vitro cadaveric biomechanical study. Long posterior spinal fusion is a standard treatment for adult spinal deformity. However, these rigid constructs are known to alter motion and stress to the adjacent non-instrumented vertebrae, increasing the risk of proximal junctional kyphosis (PJK). This study aimed to biomechanically compare a standard rigid construct vs constructs "topped off" with a semi-rigid construct. By understanding semi-rigid constructs' effect on motion and overall construct stiffness, surgeons and researchers could better optimize fusion constructs to potentially decrease the risk of PJK and the need for revision surgery. Nine human cadaveric spines (T1-T12) underwent non-destructive biomechanical range of motion tests in pure bending or torsion and were instrumented with an all-pedicle-screw (APS) construct from T6-T9. The specimens were sequentially instrumented with semi-rigid constructs at T5: (i) APS plus sublaminar bands; (ii) APS plus supralaminar hooks; (iii) APS plus transverse process hooks; and (iv) APS plus short pedicle screws. APS plus transverse process hooks had a range of motion (ie, relative angle) for T4-T5 and T5-T6, as well as an overall mechanical stiffness for T1-T12, that was more favourable, as it reduced motion at adjacent levels without a stark increase in stiffness. Moreover, APS plus transverse process hooks had the most linear change for range of motion across the entire T3-T7 range. Present findings suggest that APS plus transverse process hooks has a favourable biomechanical effect that may reduce PJK for long spinal fusions compared to the other constructs examined.

Comparative effectiveness of different pedicle screw density patterns in spinal deformity correction of small and flexible operative adolescent idiopathic scoliosis: inverse probability of treatment weighting analysis

PurposesAn optimal pedicle screw density for spinal deformity correction in adolescent idiopathic scoliosis (AIS) remains poorly defined. We compared radiographic correction, operative time, estimated blood loss, and implant cost among different screw density patterns in operatively treated AIS patients.MethodsA retrospective observational cohort study of AIS patients who underwent posterior spinal fusion using all-pedicle screw instrumentation was conducted from January 2012 to December 2018. All patients were categorized into three different pedicle screw density groups: the very low density (VLD), the low density (LD), and the high density (HD) group. The comparative effectiveness between each pairwise comparison was performed under the inverse probability of the treatment weighting method to minimize the possible confounders imbalance among treatment groups. The primary endpoints in this study were the degrees of correction and deformity progression at 2 years postoperatively.ResultsA total of 174 AIS patients were included in this study. The adjusted treatment effects demonstrated similar degrees of deformity correction after 2 years in the three treatment groups. However, the VLD and LD group slightly increased the curve progression at 2 years compared to the HD group by 3.9° (p = 0.005) and 3.2° (p = 0.044), respectively. Nevertheless, the limited screw density patterns (VLD and LD) significantly reduced the operative time, estimated blood loss, and implant cost per operated level.ConclusionThe limited pedicle screw pattern (VLD and LD) in relatively flexible AIS spinal deformity correction results in similar coronal and sagittal radiological outcomes while reducing operative time, estimated blood loss, and implant cost compared to the high-density pedicle screw instrumentation.

Is Lenke Rule About Selective Thoracic Fusion Applicable for Younger Adult Idiopathic Scoliosis Under 40 Years of Age: Comparison With Adolescent Patients.

Retrospective study. To evaluate the surgical outcomes of younger adult idiopathic scoliosis patients (YAdIS) with selective thoracic fusion by comparing them with adolescent idiopathic scoliosis (AIS). Seventy-two idiopathic scoliosis patients (36 adults and 36 adolescents) treated by posterior-only all-pedicle screw technique were retrospective reviewed and matched by fusion levels. Radiographic parameters were evaluated preoperatively, postoperatively, and at final follow-up. Operating time, blood loss, transfusion, and complications were noted. The clinical outcome was assessed by the Scoliosis Research Society-22 questionnaire (SRS-22). The major thoracic curves in YAdIS and AIS groups were 56.3° ± 9.7°, 53.3° ± 10.1° and corrected to 17.2° ± 7.3°, 14.9° ± 7.5° respectively without significant difference in correction rate (69.3% vs 72.0%). For the lumbar curve, Cobb angles in 2 groups were 35.6° ± 10.1°and 31.4 ± 9.2° preoperatively, and were spontaneously corrected to 18.5° ± 9.0° and 12.6° ± 8.2°.Correction rates were 48.0% and 59.8% (P < .05). Preoperative and postoperative coronal vertebra alignments (CVA) in the YAdIS group were 20.6 ± 9.7mm and 16.8 ± 7.9mm (P > .05), while in the AIS group was 17.8 ± 10.5mm and 9.7 ± 8.3mm (P < .05). However, sagittal parameters showed significant improvements in thoracic kyphosis in both groups (P < .05). Complication rates were 25% vs 11.1% (P = .13) with no significant difference. Preoperative SRS-22 was worse in the YAdIS group than AIS group. All the scores were significantly improved postoperatively in the YAdIS group. However, in the AIS group, only SRS scores improved significantly. YAdIS can also be treated very well with selective thoracic fusion based on the Lenke rule used for AIS.

All Pedicle Screw versus Hybrid Hook-Screw Instrumentation in the Treatment of Thoracic Adolescent Idiopathic Scoliosis (AIS): A Prospective Comparative Cohort Study.

Background: Posterior spinal correction and fusion remains the most common surgical treatment in AIS. Surgeons currently favour all pedicle screw (AS) correction techniques with alternative implants being less utilised. The purpose of this study was to assess whether a hybrid hook–screw (HS) construct could achieve similar outcomes. Methods: A single centre, prospective cohort study was conducted. Patients with moderate and severe thoracic AIS (Lenke 1) were included. Clinical and radiological results of a standardised hybrid HS technique were compared with those obtained with an AS construct. All patients had a minimum 2-year follow-up. Results: 160 patients were included in this series (80 patients/group). The HS group had significantly reduced surgical time, blood loss and implant density. Both techniques achieved ≥75% scoliosis correction. The HS group was superior in restoring thoracic kyphosis and global sagittal balance with an average 31% increase in kyphosis compared to 10% with the AS group (p < 0.001). There was significant improvement in SRS-22 scores at 2 years postoperative (p < 0.001) in both groups. There were no neurological or visceral complications related to instrumentation, no detected non-union and no reoperations. The HS implant cost was significantly lower than that of AS, with a mean instrumentation saving of almost £2000/patient. Conclusion: A standardised hybrid HS technique achieved excellent correction of thoracic scoliosis, high patient satisfaction and low complication rates in patients with thoracic AIS. These results were comparable to the AS group. The HS technique achieved better correction of thoracic kyphosis and sagittal balance than the AS technique, together with reduced surgical time, blood loss and implant cost.

Clinical Issues in Indication, Correction, and Outcomes of the Surgery for Neuromuscular Scoliosis: Narrative Review in Pedicle Screw Era.

Surgical treatment for neuromuscular scoliosis has evolved with pedicle screw instrumentation and the improvement of perioperative management. We aimed to review recent papers related to posterior surgical correction with a pedicle screw system for neuromuscular scoliosis, particularly cerebral palsy and muscular dystrophy, in terms of indication, correction method, and outcomes. The most remarkable change was the posterior-only operation with all-pedicle screw fixations. With this change, operation time, blood loss, and postoperative complications decreased. Furthermore, spinal osteotomy could be performed with the pedicle screw system for severe scoliosis. S2-alar-iliac screws demonstrated favorable outcomes in terms of stability and complication, but a question remains about saving the mobile segment for sitting balance, interaction between the hip and spine, effect to the sagittal balance, and proximal junctional problem. The quality of life improvement was more definite in patients with cerebral palsy. The improvement of respiratory function in Duchenne muscular dystrophy was not certain, although an increase of spinal height, thoracic cavity size, and absolute forced vital capacity have been reported. Further prospective studies or randomized clinical trials are needed to evaluate the long-term outcomes of lumbosacral fixation, preservation of the lumbosacral joint, or functional improvement considering the different etiology.

Complications of dual growing rod with all-pedicle screw instrumentation in the treatment of early-onset scoliosis

BackgroundTreatment of early-onset scoliosis (EOS) is still a challenge to patients, families, and surgeons. Previous studies have indicated that EOS patients are at high risk for complications following growth-friendly surgery. This study was performed to evaluate the results and complications of all-pedicle screw dual growing rod instrumentation in the treatment of EOS.MethodsIn an IRB-approved retrospective study, we searched the electronic medical records of our institution for all patients who underwent posterior spinal instrumentation for scoliosis between March 2014 and March 2017. Patients under the age of 10 at the time of surgery who were treated with a growth-friendly technique were then selected. Patients with incomplete records and less than 2 years of follow-up were excluded. Charts, operative notes, clinic visits, and radiographs were extracted. Radiographs were reviewed, and the main curve Cobb angle, thoracic kyphosis, pelvic tilt, pelvic incidence, sacral slope, and proximal junctional angles were measured. We specifically looked for any intra-operative or post-operative complications. Statistical analysis was performed to determine the risk factors of complications.ResultsA total of 42 patients with a mean age of 4.8 ± 2.1 years (range, 1.5–8 years) were included in the final analysis. Patients were followed for a median of 34 months (range, 24–55). The major curve was corrected from a mean of 42.9° ± 10.7° to 28.8° ± 9.6° at the latest follow-up. Proximal junctional angles and thoracic kyphosis increased significantly during the follow-up period (both P values < 0.001). A total of 7 complications (17%) were observed. Four patients (10%) developed superficial surgical site infections, all of which resolved with antibiotics and one round of surgical debridement. Three cases (7%) of proximal junctional kyphosis (PJK) were encountered during the study period, none of which required revision surgery. Pre-operative thoracic kyphosis was the only significant risk factor for the development of PJK.ConclusionsOur findings suggest that in settings without access to magnetically controlled growing rods, dual growing rods with all-pedicle screw instrumentation is still a viable treatment strategy with comparable results and complications. The most common complications are infection and PJK, with the latter being associated with a larger pre-operative thoracic kyphosis.

Spinal balance and lumbar curve stability after selective thoracic fusion in idiopathic scoliosis.

Selective thoracic fusion (STF) for double curve patterns in idiopathic scoliosis is an attractive treatment option. However, short-term coronal decompensation and truncal imbalance are known findings. Previous studies with hook constructs showed that eventually balance is achieved via an increase in lumbar curve magnitude, as the lumbosacral obliquity did not change following surgery. Our aim is to investigate patients with idiopathic curves who underwent STF using all-pedicle screw constructs to determine if the uninstrumented lumbar curve and lumbosacral obliquity responded in the same manner as was previously reported with all-hook constructs. 102 consecutive patients with Lenke 1B, 1C or 3C curves who underwent STF using all-screw constructs at a single institution were included in this study. Radiographic assessment was performed, and patient reported outcomes were obtained. Subgroup analyses were performed based on preoperative thoracic: lumbar curve ratio as well as lumbar curve magnitude. Overall, the patients showed statistically significant improvement in both trunk shift and L4-pelvis obliquity at final follow-up. The uninstrumented lumbar curves trended toward improvement over time, but did not reach statistical significance (p = 0.107). SRS-30 scores were statistically significantly improved in multiple domains. Selective thoracic fusion is an excellent treatment option in most double curve patterns. Balance in the coronal plane is predictably achieved at 2-year follow-up. The lumbosacral obliquity improves more with screw technology than was previously found with hook constructs; therefore, the improvement in balance over time does not depend upon an increase in the uninstrumented lumbar curve. IV.

Incidence of Proximal Junctional Kyphosis With Pedicle Screws at Upper Instrumented Vertebrae in Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis.

Study Design:Longitudinal cohort.Objectives:Posterior spinal fusion (PSF) using all-pedicle screw constructs has become the standard procedure in the treatment of adolescent idiopathic scoliosis (AIS). However, there have been several reports that all-pedicle screw constructs or the use of pedicle screws at the upper instrumented vertebrae (UIV) increases the incidence of proximal junctional kyphosis (PJK). We aimed to evaluate the impact of instrumentation type on the incidence of PJK following PSF for AIS.Methods:We performed a stratified random sampling from 3654 patients enrolled in a multicenter database of surgically treated AIS to obtain a representative sample from all Lenke types. Patients were then allocated into 3 groups based on the instrumentation type: all-pedicle screw (PS), hook at UIV with pedicle screws distally (HT), and hybrid constructs (HB). We measured proximal junctional angle (PJA) and defined PJK as PJA ≥ 10° and PJA progression of >10° at the final follow-up.Results:Fifteen (4.3%) of 345 cases had PJK. PJK was significantly more common in PS (11%) compared with HB (1%) and HT (0%) (P < .001). PJK patients were similar to non-PJK patients regarding age, sex, curve type, UIV, and preoperative coronal Cobb angle. Thoracic kyphosis was significantly higher in the PJK group before surgery. Patients who developed PJK had a statistically significantly larger negative sagittal balance compared with the non-PJK group.Conclusion:The incidence of PJK was 4.3% and was more common in all-pedicle screw constructs. Using hooks at UIV might be a treatment strategy to limit PJK.

Posterior Spinal Fusion With Multilevel Posterolateral Convex Disc Releases for the Treatment of Severe Thoracolumbar Scoliosis.

Severe, rigid thoracolumbar scoliosis presents a surgical challenge to achieve 3-dimensional correction, maximize distal motion segments, and avoid operative morbidity conferred by combined anterior-posterior approaches or 3-column osteotomies. We present a new approach for releasing these curves, using multilevel posterolateral convex disc release (PCDR) and posterior instrumented fusion. There were 3 adults and 1 adolescent (mean age, 31.8 years; 2 females) with severe progressive thoracic and transforaminal lumbar (major) idiopathic scoliosis (IS) who were treated with 3-level PCDR, multiple posterior column osteotomies, and posterior instrumented thoracolumbar fusion with all-pedicle screw constructs. Restoration of global coronal and sagittal alignment was achieved for all patients (minimum 2-year follow-up). Lowest instrumented vertebra (LIV) was L4 in 2 patients and L3 in the remaining 2. All except 1 were fused to the lower end vertebra. Postoperatively, mean thoracolumbar curve was reduced from 77.3° (range, 69°-91°) to 21.8° (72%Δ), LIV tilt decreased from 26.8° to 8.3°, and LIV translation improved (2.5-1.2 cm; 58%Δ), whereas lumbar lordosis remained unchanged. Average central sacral vertical line shift measured via C7 sagittal vertical axis changed from 1.4 to -0.7 cm. There were no complications except for dysesthesias in the lower extremity on the side of the PCDR in 1 patient, which resolved after 3 months. Severe thoracolumbar IS presents a surgical challenge to achieve 3-dimensional correction, minimize fusion levels, and avoid procedural morbidity. PCDR is a novel technique that may facilitate this correction with minimal procedure-related morbidity.

Posterior spinal fusion for severe kyphoscoliosis in a Loeys-Dietz syndrome patient with a large syringomyelia

Spinal deformity is a characteristic feature of Loeys-Dietz syndrome (LDS). Surgical correction in LDS is indicated when the deformity is progressive to avoid neurological deficits, respiratory impairment, and back pain. However, few reports exist on the surgical treatment of spinal deformity in LDS, and no therapeutic standards have been established. We described the clinical and radiological outcomes of a patient with LDS receiving surgery for severe kyphoscoliosis.A 21-year-old male patient with LDS underwent posterior spinal fusion with an all-pedicle screw construct from T10 to L5 for a preoperative main curve Cobb angle of 70 degrees and kyphotic angle of 49 degrees. The postoperative Cobb angle of the main curve and kyphotic angle improved to 36 and 8 degrees, respectively. Correction surgery was performed with frequent motor evoked potential testing, taking care not to cause motor paralysis. Ameliorated low back pain and improvements in clinical questionnaire scores were noted at 21 months after surgery. No perioperative complications were reported.Based on the present case, posterior spinal fusion represents a good correction option for severe spinal deformity in LDS with syringomyelia. Careful preoperative examination and treatment for neurovascular and neurological lesions is advised to prevent severe complications.

High density all-pedicle screw technique in correction of high-degree (≥70 degrees) scoliosis with sequential derotation without osteotomies

Background: Pedicle screws have become the principal method for scoliosis correction by allowing secure segmental three-column fixation, with many advantages over other fixation methods. This prospective study was conducted in 23 patients to evaluate the efficacy and safety of high-density pedicle screws in the correction of high degrees (≥70 degrees) of adolescent idiopathic scoliosis with sequential derotation without osteotomies. Methods: The traditional posterior approach was done with pedicle-screw instrumentation at each level of the concave side unless the pedicle was hypoplastic or markedly deformed and could not support pedicle-screw purchase. For the convex side, the surgeons instrumented at least the three lower-most vertebrae, three upper-most vertebrae, and at least three apical vertebrae. The mean preoperative Cobb angle of the major curve was 82.34 degrees. Results: The Cobb angle had been corrected to 19.65 degrees postoperatively and to 20.69 degrees at latest follow-up. The percent of curve correction was 76.1%. The Scoliosis Research Society (SRS) 22 questionnaire score improved significantly from a mean of 2.3 preoperatively to 3 at latest follow-up. There was no metal failure or pseudarthrosis detected during the follow-up period. The high-density screw technique allows control of each vertebra in the curve. Using a tough rod with a rod derotation technique aligns the coronal position of each vertebra. Conclusions: A high-density pedicle-screw technique through a posterior-only approach is a safe, effective method for treatment of severe adolescent idiopathic scoliosis avoiding the anterior approach-related complications. Level of Evidence: Level IV.

Proximal Anchor Constructs and Its Influence on Surgical Outcome in Growth Rod Technique; A Comparison Between Rib Hooks and Pedicle Screws

Study DesignRetrospective. ObjectivesTo compare outcomes and complications of all-pedicle screw against hybrid constructs as proximal anchors in traditional growth rod technique. Summary of Background DataTraditional distraction-based growth rods, although the preferred technique in treating progressive curves in early-onset scoliosis (EOS) is not free from complications. Surgical outcome and implant-related complications can be influenced by the choice of construct, but there is a paucity of evidence in literature comparing different constructs with these techniques. MethodsA retrospective review was performed of 28 consecutive patients with progressive EOS treated between 2009 and 2015 with growth rod technique. Patients were divided into two groups; Standard group (SG), where all pedicle screw construct was used; and Hybrid group (HG), where proximal rib hooks and distal pedicle screws were used. Pre- and postoperative clinical and radiologic parameters and complications were recorded and compared. ResultsThere were 13 patients (8 females, 5 males) in SG and 15 patients (13 females, 2 males) in HG. There was statistically significant improvement in scoliosis correction and length gain after initial surgery in both groups, where patients in SG showed better correction than HG. However, neither the radiologic parameters nor the complication rates showed any statistically significant difference between the two groups. ConclusionData from our study indicate that the proximal anchors, whether spine-based or rib-based, do not differ much in their outcome and complication rates, and the success of growing-rod technique depends largely on the security of cephalad and caudal foundations. Level of EvidenceLevel IV.

252. Incidence of PJK with pedicle screws at upper instrumented vertebrae in posterior spinal fusion for adolescent idiopathic scoliosis

BACKGROUND CONTEXT Posterior spinal fusion (PSF) using all-pedicle screw constructs has become the standard surgical treatment for adolescent idiopathic scoliosis (AIS). However, some studies have shown that all-pedicle screw constructs or the use of pedicle screws at the upper instrumented vertebrae (UIV) increases the incidence of proximal junctional kyphosis (PJK). The purpose of this study is to examine the impact of different instrumentation types on the incidence of PJK following PSF for AIS. PURPOSE To determine if all-pedicle screw constructs increase the incidence of PJK following PSF for AIS, as pedicle screw placement at the UIV may violate the supra-adjacent facet capsules. STUDY DESIGN/SETTING Longitudinal cohort study. PATIENT SAMPLE Multicenter database of surgically treated AIS. OUTCOME MEASURES PJA. METHODS A multicenter database of surgically treated AIS was used. A stratified random sampling was done to obtain a representative sample from all curve types. Patients were included if they underwent PSF, and if immediate postoperative and final follow-up radiographs were available. The patients were grouped by instrumentation type: all-pedicle screw (PS), hook at UIV with distal all-pedicle screw (HT), and hybrid (HB). PJA was measured as the angle between UIV and UIV+2 on lateral full-length standing radiographs immediately postoperative and at the final follow-up. PJK was defined as PJA ≥ 10° or PJA progression of ≥ 10° at the final follow-up. RESULTS The PS, HT and HB groups included 128, 111 and 106 patients, respectively. There was no difference in baseline demographic and radiographic characteristics among the groups. Fifteen cases (4.3%) developed PJK at the latest follow-up (average 2.2 years). PJK was more common in the PS group (p CONCLUSIONS The incidence of PJK following PSF for AIS was 4.3% and was more common in an all-pedicle screw constructs compared to hybrid or UIV-hook distal pedicle screw constructs. Using hooks at UIV might be a treatment strategy to limit PJK. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.

The use of sublaminar bands in treatment of spinal deformity: an operative technique

Background: Pedicle screws are commonly used in the surgical treatment and correction of spinal deformity. In recent years, polyester bands have been used as adjuncts to pedicle screws and hooks. Currently, the implementation of polyester sublaminar bands in the treatment of pediatric spinal deformity has led to improved results with similar complications as other techniques. This paper further highlights the innovative use of sublaminar bands utilized in a hybrid construct leading to improved results. Furthermore, we describe the surgical technique and indications for sublaminar bands in pediatric spinal deformity. Methods: Innovative sublaminar band hybrid construct description and comparison to current practices regarding surgical indications, complications, and comparative outcomes compared to the use of pedicle screw fixation. Results: The described hybrid sublaminar band implementation further validates the use of hybrid constructs as an innovative method and approach to pediatric spinal deformity. Hybrid constructs with sublaminar band utilization may become more favored in the future as they continue to have a safe track record within the literature and are able to optimize sagittal correction better than an all-pedicle screw construct, all while reducing operative time, blood loss, and radiation exposure. Conclusions: This novel surgical technique of sublaminar band utilization offers a user-friendly procedure with a short learning curve. This technique, if applied in the correct surgical candidates, has been proven to be a successful method of spinal deformity correction in pediatric spinal fusions. Level of Evidence: Level IV.

Radiographic and Functional Outcome in Adolescent Idiopathic Scoliosis Operated With Hook/Hybrid Versus All-Pedicle Screw Instrumentation—A Retrospective Study in 149 Patients

Study DesignRetrospective cohort study. ObjectiveTo compare radiographic outcome and health-related quality of life in patients with adolescent idiopathic scoliosis (AIS) treated with hook/hybrid (H/H) or all-pedicle screw (PS) instrumentation. Summary of Background DataPS instrumentation has largely replaced H/H in the surgical treatment of AIS but whether a normalized sagittal profile can be obtained with the PS construct is still debated. Additionally, comparative studies assessing HRQL and surgical complications are needed. MethodsTwo consecutive series of surgically treated AIS patients were included. Surgical treatment consisted of H/H or low-profile all-PS instrumentation. Radiographic and clinical follow-up, including SRS-22r questionnaires, was performed a minimum of two years postoperatively. ResultsThere were 85 and 64 patients in the H/H and PS group, respectively. The groups did not differ on baseline parameters apart from a lower flexibility in the H/H group (34% ± 14% vs. 39% ± 14% in the PS group, p = .026). Mean curve correction at final follow-up was 31% ± 13% versus 49% ± 12% in the H/H and PS group, respectively (p < .001), and mean loss of correction was 7° versus 4° (p < .001). The Cincinnati correction index was significantly higher in the PS group at final follow-up (p < .001). Postoperative thoracic kyphosis was significantly higher in the H/H group (27° ± 11° vs. 22° ± 11° in the PS group) with a mean change in kyphosis of 3° ± 9° versus −3° ± 12° in the H/H and PS group, respectively. SRS-22 scores did not differ between the two groups (p > .090), and the reoperation rate at final follow-up was 9% in the H/H group and 6% in the PS group (p = .556). ConclusionsIn a large consecutive cohort of AIS patients followed for a minimum of two years, we found a significantly better curve correction and less loss of correction with PS instrumentation compared to H/H. There was no significant difference in SRS-22r scores at final follow-up. Level of EvidenceLevel III.

Improved restoration of thoracic kyphosis using a rod construct with differentiated rigidity in the surgical treatment of adolescent idiopathic scoliosis.

OBJECTIVE The objective of this study was to compare postoperative sagittal alignment among 3 rod constructs with different rigidity profiles. METHODS This was a dual-center retrospective cohort study involving 2 consecutive cohorts in which patients were surgically treated for adolescent idiopathic scoliosis. Lenke Type 5 curves were excluded. Patients were operated on with all-pedicle screw instrumentation using 3 different rod constructs. The first group was operated on using a hybrid construct (HC) consisting of a normal circular rod on the convex side and a beam-like rod (BR) on the concave side. The second group was operated on with a standard construct (SC) using bilateral BRs in the full length of the fusion. The third group was operated on with a modified construct (MC). The modified rods have a beam-like shape in the caudal portion, but in the cranial 2 or 3 fusion levels the rod transitions to a circular shape with a smaller anteroposterior diameter. Radiographs were analyzed preoperatively and at the first postoperative follow-up (range 1-8 weeks). The primary outcome was pre- to postoperative change in thoracic kyphosis (TK), and the secondary outcome was the ability to achieve postoperative TK within the normal range. RESULTS The HC, SC, and MC groups included 23, 70, and 46 patients, respectively. The 3 groups did not differ significantly in preoperative demographic or radiographic parameters. The mean ± standard deviation of the preoperative main curve was 60.7° ± 12.6°, and the mean of curve correction was 62.9% ± 10.4% with no significant difference among groups (p ≥ 0.680). The groups did not differ significantly in coronal balance or proximal or thoracolumbar curve correction (p ≥ 0.189). Mean postoperative TK was 23.1° ± 6.3°, 19.6° ± 7.6°, and 23.4° ± 6.9° in the HC, SC and MC groups, respectively (p = 0.013), and the mean change in TK was -3.5° ± 11.3°, -7.1° ± 11.6°, and 0.1° ± 10.9°, respectively (p = 0.005). The MC group had significantly higher postoperative TK and less loss of TK compared with the SC group (p ≤ 0.018). Postoperative TK ≤ 10° was found in 12 patients (17%) in the SC group, 1 patient (5%) in the HC group, and 1 patient (2%) in the MC group (p = 0.021). There were no differences in proximal alignment, thoracolumbar alignment, or sagittal vertical axis (p ≥ 0.249). Lumbar lordosis was 58.9° ± 11.2° in the HC group versus 52.0° ± 1.3° and 55.0° ± 11.0° and the SC and MC groups, respectively (p = 0.040). CONCLUSIONS In the 3 rod constructs with different rigidity profiles, significantly better restoration of kyphosis was achieved with the use of bilateral modified rods compared with bilateral standard rods. In the MC and HC groups, the rate of severe postoperative hypokyphosis was significantly lower than in the SC group. This is the first study to describe the clinical use of a rod with a reduced proximal diameter and show marked radiographic improvement in sagittal alignment.

Posterior-Only Approach with Pedicle Screws for the Correction of Scheuermann's Kyphosis.

Study DesignRetrospective study (level of evidence: level 3).PurposeThe purpose of this study was to evaluate the clinical and radiological results of the posterior-only approach with pedicle screws for the treatment of Scheuermann's kyphosis (SK).Overview of LiteratureThe correction of SK with instrumentation can be performed using posterior-only or combined anterior-posterior procedures. With the use of all-pedicle screw constructs in spine surgery, the posterior-only approach has become a popular option for the definitive treatment of SK. In a nationwide study involving 2,796 patients, a trend toward posterior-only fusion with lower complication rates was reported.MethodsWe retrospectively reviewed the data of patients who underwent posterior-only correction for SK between January 2005 and May 2013. Patients with a definite diagnosis of SK who fulfilled the minimum follow-up criterion of 24 months were included. The thoracic kyphosis (T5–T12), lumbar lordosis (L1–S1), and thoracolumbar junction (T10–L2) angles were measured from preoperative, postoperative, and last control radiographs. Sagittal balance, thoracic length, thoracic diameter, Voutsinas index and the sacral slope, pelvic tilt, proximal junction kyphosis, and distal junction kyphosis angles were also measured.ResultsForty-five patients underwent surgery for the treatment of SK between 2005 and 2013. After applying the exclusion criteria, 20 patients (18 males and 2 females) with a mean age of 19 years were included. The mean thoracic kyphosis angle was 79.8 degrees preoperatively, 44.6 degrees postoperatively, and 44.9 degrees at the last control. There were statistically significant differences between preoperative and postoperative values in the thoracic kyphosis and lumbar lordosis angles, thoracic length, thoracic diameter, and Voutsinas index (p<0.05).ConclusionsThe clinical and radiological results of the current study suggest that posterior-only fusion is an efficient technique for the treatment of SK.

Comparison of low density and high density pedicle screw instrumentation in Lenke 1 adolescent idiopathic scoliosis

BackgroundThe correlation between implant density and deformity correction has not yet led to a precise conclusion in adolescent idiopathic scoliosis (AIS). The aim of this study was to evaluate the effects of low density (LD) and high density (HD) pedicle screw instrumentation in terms of the clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes in Lenke 1 AIS.MethodsWe retrospectively reviewed 62 consecutive Lenke 1 AIS patients who underwent posterior spinal arthrodesis using all-pedicle screw instrumentation with a minimum follow-up of 24 months. The implant density was defined as the number of screws per spinal level fused. Patients were then divided into two groups according to the average implant density for the entire study. The LD group (n = 28) had fewer than 1.61 screws per level, while the HD group (n = 34) had more than 1.61 screws per level. The radiographs were analysed preoperatively, postoperatively and at final follow-up. The perioperative and SRS-22 outcomes were also assessed. Independent sample t tests were used between the two groups.ResultsComparisons between the two groups showed no significant differences in the correction of the main thoracic curve and thoracic kyphosis, blood transfusion, hospital stay, and SRS-22 scores. Compared with the HD group, there was a decreased operating time (278.4 vs. 331.0 min, p = 0.004) and decreased blood loss (823.6 vs. 1010.9 ml, p = 0.048), pedicle screws needed (15.1 vs. 19.6, p < 0.001), and implant costs ($10,191.0 vs. $13,577.3, p = 0.003) in the LD group.ConclusionsBoth low density and high density pedicle screw instrumentation achieved satisfactory deformity correction in Lenke 1 AIS patients. However, the operating time and blood loss were reduced, and the implant costs were decreased with the use of low screw density constructs.

All-Pedicle Screw Fixation With 6-mm-Diameter Cobalt-Chromium Rods Provides Optimized Sagittal Correction of Adolescent Idiopathic Scoliosis

Recently introduced cobalt-chromium (CoCr) rods that rely solely on pedicle screws produce very good results in correcting scoliotic curves. All-pedicle screws constructs are also suspected of decreasing thoracic kyphosis. The current study was designed to evaluate sagittal correction in adolescent idiopathic scoliosis patients, using 6-mm CoCr rods and all-screw constructs. A total of 61 patients treated by posterior spinal fusion and instrumentation, using all-pedicle screw constructs were included. The mean age at surgery was 15.4 years (range, 12-18 y). Forty-five patients (group A) were diagnosed with decreased thoracic kyphosis, and 16 patients (group B) had normal (35-50 degrees) thoracic kyphosis. The preoperative main Cobb angle was 62.93±19.38 degrees in group A and 73.45±22.13 degrees in group B. In group A, the postoperative main Cobb angle was 23.33±12.71 degrees. In group B, the postoperative main Cobb angle was 27.20±10.04 degrees. The T4-T12 thoracic kyphosis improved postoperatively from 18.15±10.29 to 28.18±8.35 degrees in group A. In group B, the postoperative T4-T12 thoracic kyphosis was 40.34±3.13 degrees. Statistical analysis showed a significant improvement between preoperative and postoperative values of T4-T12 thoracic kyphosis in group A. In group B, the differences in T4-T12 thoracic kyphosis values were not statistically significant. Our result demonstrates a significant improvement of T4-T12 thoracic kyphosis in the hypokyphotic group of patients and confirms that CoCr rods can produce sagittal corrections in hypokyphotic adolescent idiopathic scoliosis patients. Our results confirm the benefit of combining all-pedicle screw constructs with a posterolateral translational in situ bending procedure to correct hypokyphosis directly.