Background Three-dimensional (3-D) printing offers the opportunity to create patient-specific guides for pedicle screw placement based on CT-generated models. This technology might allow for more-accurate placement of pedicle screws in patients with severe congenital scoliosis who have rotated vertebrae and small pedicles, but to our knowledge, this premise has not been tested. Questions/purposes (1) Is the use of 3-D printing and pedicle guider technology as or more accurate than the use of the freehand technique for pedicle-screw placement in patients with severe congenital scoliosis? (2) Does surgical time differ with the use of these guiders? (3) Are complications less common in patients treated with this new approach to pedicle-screw placement? Methods A prospective controlled study was conducted of patients with severe congenital scoliosis (major curve ≥ 90°) from June 2016 to June 2018. During this period, we treated 93 patients with congenital scoliosis; 32 had severe scoliosis with a major curve ≥ 90°. The patients were divided into a pedicle guider group (n = 15) and a control group (n = 17) based on their willingness to use pedicle guider technology, which was considered a research technology. With the numbers available, there were no between-group differences in terms of age, sex, BMI, or parameters related to curve severity or flexibility, and all patients in both groups had severe curves. Preoperative and postoperative low-dose CT scans were performed in the two groups. In the pedicle guider group, custom software was used to design the pedicle guider, and a 3-D printer was used to print a physical spinal model and pedicle guiders. The pedicle guiders were tested on the surface of the physical spinal model before surgery to ensure proper fit, and then used to assist pedicle screw placement during surgery. A total of 244 screws were implanted with the help of 127 pedicle guiders (254 guiding tunnels) during surgery in the PG group. Five predesigned pedicle guiders were abandoned due to an unstable match, and the success rate of assisted screw placement using a pedicle guider was 96% (244 of 254). The freehand technique was used in the control group, which relied on anatomic localization to place pedicle screws. The accuracy of pedicle screw placement was evaluated with CT scans, which revealed whether screws had broken through the pedicle cortex. We compared the groups in terms of accuracy (defined as unanticipated breaches less than 2 mm), surgical time, time to place pedicle screws, and screw-related complications. Results A higher proportion of the screws placed using pedicle guider technology were positioned accurately than were in the control group (93% [227 of 244] versus 78% [228 of 291]; odds ratio, 3.69 [95% CI, 2.09–6.50]; p<0.001). With pedicle guider use, operative time (296 ± 56 versus 360 ± 74; 95% CI, -111 to -17; p = 0.010), time to place all screws (92 ± 17 versus 118 ± 21; 95% CI, -39 to -12; p = 0.001), and mean time to place one screw (6 ± 1 versus 7 ± 1; 95% CI, -2 to 0; p = 0.011) decreased. One patient in the pedicle guider group and four in the control group experienced screw-related complications; the sample sizes and small number of complications precluded statistical comparisons. Conclusions In this small, preliminary study, we showed that the accuracy of the surgical technique using spinal 3-D printing combined with pedicle guider technology in patients with severe congenital scoliosis was higher than the accuracy of the freehand technique. In addition, the technique using pedicle guider technology appeared to shorten operative time. If these findings are confirmed in a larger study, pedicle guider technology may be helpful for situations in which intraoperative CT or O-arm navigation is not available. Level of Evidence Level II, therapeutic study.

Background: There are several risk factors for proximal junctional kyphosis (PJK) in adolescent idiopathic scoliosis (AIS) surgery. Decreased rod contouring angle (RCA) has been proposed as a risk factor for PJK, but the role of difference between proximal junctional angle (PJA) and RCA (PJA-RCA) has not been fully investigated. The aim of this study was to assess the role of PJA-RCA for the development of postoperative PJK in AIS. Methods: We performed a retrospective analysis of 96 AIS patients who underwent posterior segmental spinal instrumentation and fusion between the years 2012 and 2018 (minimum 1.5-year and average 2-year follow-up) at a single institution. Each patient was measured on preoperative, postoperative and final follow-up long-cassette standing radiographs. The PJA-RCA was regarded as a new definition that reflects the match degree between proximal rod contouring and vertebra curvature, and radiographic parameters were compared between PJK and non-PJK group. Results : Among the 96 patients with a mean age of 14.00 years (± 0.82), the overall incidence of PJK was 22%. PJK group showed a significantly greater preoperative SVA (P = 0.032) and larger correction of SVA (P = 0.007) than non-PJK group. At the last follow-up, PJK patients had significantly greater LL (P = 0.046). Patients in the PJK group had significantly greater preoperative PJA-RCA than the non-PJK group (4.07±3.30 vs. 1.42±4.28, P = 0.024). However, RCA was not significantly different between two groups (3.88 ± 4.34 vs. 2.86 ± 3.36, P = 0.405). In addition, Pearson correlation coefficient showed a significant correlation between the change of SVA and the last follow-up PJA (r =-0.208, P = 0.042). Preoperative PJA-RCA and postoperative PJA-RCA demonstrated similar results which showed a strong correlation with the last follow-up PJA (r = 0.528 and r = 0.532 respectively, P < 0.000). Conclusions: As a new reflex of improper rod contouring, large PJA-RCA is a risk factor for PJK in AIS, and PJK might be a compensation mechanism rather than complication when spine is shifted and overcorrected.

Objective This is the first systematic review and meta-analysis on the overall incidence of intraspinal abnormalities in patients with congenital scoliosis (CS) and potential influencing factors. Methods We searched three large electronic databases (PubMed, EMBASE, and Cochrane Library) for potentially relevant studies. The quality of the included studies was assessed independently by two authors using the Methodological Index for Non-Randomized Studies (MINORS) criteria. Data on the number of CS patients, number of CS patients with intraspinal abnormalities, sex of the patients, and CS types were extracted from the included studies. R software was used to pool and analyze all the extracted data. Results This meta-analysis included 10 articles, and 671 of 1863 CS patients undergoing magnetic resonance imaging (MRI) examinations were identified to have intraspinal abnormalities. The overall incidence of intraspinal abnormalities in the patients with CS was 37% (95% CI, 29–45%). Diastematomyelia was the most common intraspinal abnormality and was detected in 45.60% of the patients with intraspinal abnormalities (306/671). The remaining intraspinal abnormalities included syringomyelia (273/671, 40.69%), tethered cord (190/671, 28.32%), low conus (58/671, 8.64%), intraspinal mass (39/671, 5.81%), Chiari malformation (32/671, 4.77%), fatty filum (27/671, 4.02%), spina bifida (occulta excluded) (17/671, 2.53%), tumor (17/671, 2.53%), cyst (12/671, 1.79%), syringomyelus (4/671, 0.60%), dural ectasia (1/671, 0.15%), and undiagnosed cord MRI hyperintensity (1/671, 0.15%). The patient’s sex and CS type were not factors that affected the incidence of intraspinal abnormalities in CS patients (all P > 0.05). Conclusions This meta-analysis revealed that the overall incidence of intraspinal abnormalities detected by MRI in CS patients was 37%. Diastematomyelia was the most common intraspinal abnormality. The patient’s sex and CS type were not factors that affected the incidence of intraspinal abnormalities in CS patients.

Rationale: Primary Extranodal Natural Killer/T-Cell Nasal-Type Lymphoma (ENKTCL) of spine is rarely reported. This case study presents a rare case of ENKTCL originating from the sixth thoracic vertebra.Patient concerns: Here, we present a case of 49-year-old Asian male with chest and back pain. Physical examination revealed the myodynamia of both lower limbs decreased from IV degree to 0 degree, reflexes of both lower limbs and a large area of cutaneous sensation below xiphoid process disappeared in 3 days.Diagnoses: In immunophenotype analysis, CD2, CD3, CD7, and CD68 were positive and CD56 was suspiciously positive. Granzyme B and T-cell intracellular antigen (TIA-1) were also positive and in situ hybridization was positive for Epstein-Barr virusencoded mRNA (EBER). Ki-67 was 60%+. Nuclide bone scan showed that the nuclide was unusually concentrated in the sixth thoracic vertebra which considered extremely active and slightly concentrated in the right sacrolilac joint. Magnetic resonance imaging detected an abnormal signal in the sixth thoracic vertebra with corresponding paravertebral and intraspinal occupying lesion. Based on the above features, a diagnosis of ENKTCL was made.Interventions: This patient was treated with surgery and symptomatic supportive treatment.Outcomes: The myodynamia of patient's both lower limbs were elevated to I degree after the operation with chest and back pain partly relieved. However, the patient died about 3 months later.Lessons: ENKTCL could originate from spine. Clinicians should be alert for early stage diagnose and distinguish it from some common spinal tumor such as neurofibroma and hemangioma. Abbreviations: CT = computed tomography, EBER = Epstein-Barr virus-encoded mRNA, ENKTCL = extranodal NK/T-cell lymphoma, nasal type, OS = overall survival, PET-CT = positron emission tomography, PFS = progression-free survival, TCR = T-cell receptor, TIA-1 = T-cell intracellular antigen.