Is it necessary to extend fusion to L4 when correcting pediatric L5-S1 spondylolisthesis?

OBJECTIVE: The objective of this study was to investigate whether extending fusion to L4 is imperative in the surgical treatment of pediatric L5-S1 spondylolisthesis. METHODS: This retrospective analysis encompassed 68 pediatric cases of dysplastic L5-S1 spondylolisthesis who underwent posterior lumbar interbody fusion surgery at two hospitals. Patients were categorized into two groups based on the upper instrumented vertebra (group L4 and group L5). Data were collected from medical records and radiological images obtained preoperatively and at last follow-up. Radiographic parameters including slip percentage (SP), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), Spinal Deformity Study Group dysplastic lumbosacral angle (SDSG-LSA), pelvic tilt (PT), Dubousset's lumbosacral angle (Dub-LSA), sacral slope (SS), and severity index (SI) were measured. Surgery-related data and complication data were also collected. The incidence rates of complications were compared, including those of neurological deficit, adjacent-segment instability (ASI), and other complications. ASI was defined as progression of slippage > 3 mm or posterior opening > 5° in the adjacent segment. Clinical outcomes were assessed with the numeric rating scale (NRS) and the Oswestry Disability Index (ODI) scores. The follow-up period for all patients lasted a minimum of 2 years. RESULTS: Among all 68 patients, group L4 consisted of 15 patients and group L5 comprised 53 patients. The patients included in both groups had comparable baseline demographic characteristics and radiographic parameters. Postoperative SP and SDSG-LSA were significantly lower in group L5 (p < 0.05). No other postoperative radiographic differences were observed between groups. One patient in group L4 and 3 patients in group L5 experienced transient neurological deficits (p > 0.05). There were 13 cases of ASI in group L5 compared with none in group L4 (24.5% vs 0%, p > 0.05). Of the 13 patients with ASI, 4 underwent revision surgery due to L4-5 level instability and clinical symptoms. The remaining individuals exhibited no symptoms, and regular annual follow-up assessments are being conducted for all patients. The NRS and ODI scores at final follow-up did not exhibit any significant differences between the two groups. CONCLUSIONS: Fusion to L5 could achieve comparable satisfactory results to fixation to L4, albeit with increased likelihood of ASI. Extension of fusion to L4 may not be necessary for most patients with pediatric L5-S1 spondylolisthesis.

Rb3MgB5O10 and LiBaAl(BO3)2: covalent tetrahedra MO4-containing borates with deep-ultraviolet cutoff edges.

Borates are favored by materials scientists and chemists because of the significant electronegativity difference between B and O atoms and their flexible assembly modes resulting in abundant structures and excellent properties. For the design of deep-ultraviolet (DUV) optical crystals with excellent macroscopic performance, it is crucial to choose appropriate cations and anionic groups and microscopically reasonable assembly patterns. Herein, by introducing covalent tetrahedra ([MO4], M = Mg, Al), two new mixed alkali metal and alkaline earth metal borates, Rb3MgB5O10 and LiBaAl(BO3)2, were synthesized using the melt method and high-temperature solution method. They contain M-B-O two-dimensional (2D) layers (2∞[MgB5O10] and 2∞[Al(BO3)2], respectively) composed of isolated B-O groups ([B5O10]5- and [BO3]3-, respectively) and metal-centered tetrahedral connectors ([MgO4]6- and [AlO4]5-, respectively). Combining experiments and theoretical calculations shows that the two compounds have short cutoff edges (<200 nm) and moderate birefringences. Further analysis manifests that the isolated [MO4] covalent tetrahedra can optimize the arrangement of anion groups, guarantee the balanced optical properties of materials, and point out the direction for further exploration of novel borate structures.

Scoliosis risk factors and outcomes in children with dysplastic spondylolisthesis undergoing surgical reduction and fixation.

Purpose: To explore scoliosis risk factors and outcomes in children with dysplastic spondylolisthesis undergoing surgical reduction and internal fixation. Methods: We retrospectively analyzed 56 children with dysplastic spondylolisthesis who underwent surgical reduction and internal fixation. Patients were grouped according to presence of scoliosis before surgery. Radiographic parameters measured before surgery included pelvic incidence, pelvic tilt, sacral slope, coronal Cobb angle, slip percentage, Dubousset's lumbosacral angle, lumbar lordosis, sagittal vertical axis, and Spinal Deformity Study Group index. Groups were compared using logistic regression. Receiver operating characteristic analysis was performed to determine the optimal Spinal Deformity Study Group index cut-off value. All patients were followed up for at least 2 years. Results: The scoliosis group comprises 36 patients (mean age: 9.6 ± 2.7 years), while the no scoliosis group comprises 20 (mean age: 9.1 ± 2.4 years). Slip percentage and Spinal Deformity Study Group index were significantly higher in the scoliosis group (p < 0.01). Sacral slope and pelvic incidence were lower in the scoliosis group (p < 0.05). Univariate logistic regression analysis showed that slip percentage, Spinal Deformity Study Group index, pelvic incidence, and sacral slope were significantly associated with scoliosis. In the multivariate logistic regression analysis, only Spinal Deformity Study Group index was an independent risk factor for scoliosis. The optimal cut-off value for Spinal Deformity Study Group index was 0.288. Mean Cobb angle decreased from 20.3° ± 8.8° before surgery to 8.5° ± 8.9° at last follow-up; the mean scoliosis correction rate was 59.3%. Conclusion: Severe S1 dysplasia and high slip percentage may be risk factors for developing scoliosis in patients with dysplastic spondylolisthesis. Scoliosis resolved spontaneously after spondylolisthesis reduction and fixation in most patients. Level of evidence: 3.

Structural Motif Cosubstitution Strategy for Designing Fluoroaluminoborate with the Sr2Be2B2O7-Type Double-Layered Structure.

The cosubstitution strategy often was applied to design borate optical crystal materials. Revealingly, a fluoroaluminoborate Sr2Al2.18B5.82O13F2 with Sr2Be2B2O7 (SBBO) double-layered like configuration has been rationally designed and successfully synthesized based on structural motif cosubstitution strategy via the high-temperature solution method. In Sr2Al2.18B5.82O13F2, a structural motif, the [Al2B6O14F4] unit, with edge-sharing [AlO4F2] octahedra was filled in interlamination of double-layer structure. The research indicates that Sr2Al2.18B5.82O13F2 features a short ultraviolet cutoff edge (<200 nm) and moderate birefringence (∼0.058 @ 1064 nm). As the first reported linker in the interlamination of double-layer structures, the [Al2B6O14F4] unit enlightens the synthesis and discovery of new layered structures in borates.

Aluminoborates as Nonlinear Optical Materials.

Ultraviolet (UV) and Deep-UV (DUV, λ<200 nm) nonlinear optical (NLO) materials play a significant role to convert the wavelength of laser for producing UV/DUV coherent light in the laser industry. The Al [Ne]3s2 3p1 atom with empty d orbitals can form sp3 , sp3 d, and sp3 d2 hybrid orbitals when bonding with O/F atoms, which leads to the construction of [AlOm Fn ] (m+n=4, 5, 6) units. Therein, aluminoborates have received intensive attention due to the effective structural and functional adjustment effects of the diverse Al-O/F units. Accordingly, numerous aluminoborates as candidates for the next generation of UV/DUV NLO materials were discovered. In this review, recently discovered aluminoborates are overviewed and analyzed, including their syntheses, crystal structure features, and second-order NLO performances. We aim to provide the latest progress and outlook on the crystal chemistry of aluminoborates and boost the finding of the next NLO candidates with high performances.

Promising Deep-Ultraviolet Birefringent Materials via Rational Design and Assembly of Planar π-Conjugated [B(OH)3 ] and [B3 O3 (OH)3 ] Functional Species.

Birefringent materials play a significant role in modulating polarized light in optical communication and the laser industry. However, the discovery of deep ultraviolet (DUV, λ<200 nm) birefringent materials still faces a serious challenge. Herein, we propose hydroxylated π-conjugated [B(OH)3 ] and [B3 O3 (OH)3 ] units for designing DUV birefringent materials. Innovatively, four new hydroxyborates have been synthesized under mild synthesis conditions. They present four novel pseudo layers that benefit from the large degree of freedom assembly modes of [B(OH)3 ] and [B3 O3 (OH)3 ] genes and large birefringence (0.057-0.123@532 nm). Moreover, the Cs3 [B(OH)3 ]2 Cl3 crystal features a short DUV cutoff edge (180 nm), which further indicates that the reported compounds are potential DUV birefringent crystals. Free and flexible assembly modes of π-conjugated [B(OH)3 ] and [B3 O3 (OH)3 ] groups endow them a particular advantage as significant genes for exploring promising DUV birefringent materials.

From ß-Na2 B6 O10 to Na3 AlB8 O15 and Na3 Al2 B7 O15 : Structural Tuning of Anionic-Group Architectures by Substitution of [BO4 ] by [AlO4 ] Covalent Tetrahedra.

Two new sodium aluminum borates, Na3 AlB8 O15 and Na3 Al2 B7 O15 , have been successfully synthesized by the high-temperature solution method. They crystallize in the different space groups, P21 /c and P2/c, respectively. The B-O configurations of ß-Na2 B6 O10 , Na3 AlB8 O15 and Na3 Al2 B7 O15 are compared to feature complicated different dimensional open-framework structures caused by the substitution of [BO4 ] by [AlO4 ] covalent tetrahedra. Moreover, the experimental results indicate that Na3 AlB8 O15 and Na3 Al2 B7 O15 have short ultraviolet (UV) cutoff edges (<187 nm). The first-principles calculations show that Na3 AlB8 O15 and Na3 Al2 B7 O15 have moderate birefringence (0.075 and 0.041@1064 nm, respectively).