Real-World Effectiveness of Gelatin-Thrombin Matrix Sealant on Blood Loss in Adolescent Idiopathic Scoliosis Patients Undergoing Posterior Spinal Fusion: An Interrupted Time Series Study.

STUDY DESIGN: Retrospective cohort study with interrupted time series analysis. OBJECTIVE: To examine the clinical effectiveness of gelatin-thrombin matrix sealant (GTMS) on blood loss reduction after adolescent idiopathic scoliosis (AIS) surgery. SUMMARY OF BACKGROUND DATA: The real-world effectiveness of GTMS on blood loss reduction in AIS surgery has not been determined. PATIENTS AND METHODS: The medical records of patients receiving AIS surgery were retrospectively collected during a period before GTMS approval at our institution (January 22, 2010-January 21, 2015) as well as during a postintroduction period (January 22, 2015-January 22, 2020). The primary outcomes were intraoperative blood loss, drain output over 24 hours, and total blood loss (intraoperative blood loss + drain output over 24 h). Interrupted time series analysis using a segmented linear regression model was used to estimate the effect of GTMS on blood loss reduction. RESULTS: A total of 179 AIS patients [mean age (range): 15.4 (11-30) yr; 159 females and 20 males; 63 preintroduction patients and 116 postintroduction patients] were included. After its introduction, GTMS was used in 40% of cases. Interrupted time series analysis revealed changes of -340 mL (95% CI: -649 to -31, P = 0.03) for intraoperative blood loss, -35 mL (95% CI: -124 to 55, P = 0.44) for drain output over 24 hours, and -375 mL (95% CI: -698 to -51, P = 0.02) for total blood loss. CONCLUSIONS: The availability of GTMS was significantly associated with reduced intraoperative and total blood loss in AIS surgery. GTMS use as needed is recommended to control intraoperative bleeding in the setting of AIS surgery. LEVEL OF EVIDENCE: 3.

Reliability and validity of gait dynamic balance assessment in adult spinal deformity patients using a two-point trunk motion measuring device.

BACKGROUND CONTEXT: Adult spinal deformity (ASD) patients often complain of walking discomfort. However, dynamic balance evaluation methods of gait in ASD have not been well established. DESIGN: Case series study. PURPOSE: Characterize the gait of ASD patients using a novel two-point trunk motion measuring device. PATIENT SAMPLE: Sixteen ASD patients scheduled for surgery and 16 healthy control subjects. OUTCOME MEASURES: Trunk swing width and track length of the upper back and sacrum. METHODS: Gait analysis was performed using a two-point trunk motion measuring device on 16 ASD patients and 16 healthy control subjects. Three measurements were taken for each subject, and the coefficient of variation was determined to compare measurement accuracy between the ASD and control groups. Trunk swing width and track length were measured in three dimensions for comparisons between the groups. The relationship among output indices, sagittal spinal alignment parameters, and quality of life (QOL) questionnaire scores was examined as well. RESULTS: No significant difference was found for the precision of the device between the ASD and control groups. Compared with controls, the walking style of ASD patients tended to have larger right-left swing of the trunk (+14.0 cm and +23.3 cm at the sacrum and upper back, respectively), larger horizontal plane movement of the upper body (+36.4 cm), less vertical movement (-5.9 cm and -8.2 cm up-down swing at the sacrum and upper back, respectively), and longer gait cycle (+0.13 sec). Regarding QOL in ASD patients, greater right-left/front-back swing of the trunk, greater movement in the horizontal plane, and longer gait cycle were associated with lower QOL scores. Conversely, greater vertical movement was associated with higher QOL. CONCLUSIONS: ASD patients had unique gait characteristics, the intensity of which were associated with diminished QOL. The two-point trunk motion measuring device may be reliable and useful for the clinical assessment of balance during gait in ASD patients.

Impact of Physical Flexibility Changes on Respiratory Function after Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis Surgery.

Introduction: Corrective scoliosis surgery in patients with adolescent idiopathic scoliosis (AIS) increases thoracic volume but does not improve respiratory function (RF). This study evaluates the effect of physical flexibility (PF) improvement after scoliosis surgery on RF. Methods: This study reviewed the records of 61 consecutive patients with AIS (56 female and 5 male; mean±standard deviation age: 14.8±2.2 years, range: 11-20 years) who had undergone posterior spinal fusion (PSF) of the thoracic curve. PF evaluated as finger-floor distance (FFD) was measured preoperatively and one year after surgery. After dividing the cohort into the PF improvement group and the PF nonimprovement group, RF changes at two years postoperative were statistically compared. Using logistic regression analysis, we evaluated the impact of a PF improvement on % forced vital capacity (%FVC) two years after surgery. Results: The rate of patients with increased FVC, %FVC, and forced expiratory volume 1.0 second two years after surgery was 79%, 51%, and 80%, respectively. The PF improvement group exhibited a significantly higher gain in %FVC versus the PF nonimprovement group (P=0.043). Moreover, PF improvement significantly prevented a %FVC decrease (odds ratio 8.43, 95% confidence interval 1.92-59.70; P<0.001), with an adjusted odds ratio of 11.86 (P<0.001). Conclusions: Patients with diminished PF after PSF for AIS may be less likely to achieve postoperative %FVC improvement. As increased postsurgical %FVC had a positive effect on physical function, treatment strategies that focus on maintaining and increasing PF are desirable from an RF viewpoint.

Postoperative Residual Coronal Decompensation Inhibits Self-image Improvement in Adolescent Patients with Idiopathic Scoliosis.

STUDY DESIGN: Retrospective cohort study. PURPOSE: This study aimed to evaluate the relationship between C7 plumb line (C7PL) decompensation and the Scoliosis Research Society (SRS) 22-item patient questionnaire scores, including those related to self-image, preoperatively and 2 years after surgery. OVERVIEW OF LITERATURE: In the surgical treatment of adolescent idiopathic scoliosis (AIS), inferior trunk balance caused by C7PL decompensation can negatively affect patients' quality of life. However, there are few reports in the literature that describe or clarify how postoperative trunk imbalance affects each SRS-22 domain, including self-image domain scores. METHODS: A total of 120 patients with AIS who underwent posterior spinal fusion from August 2006 to March 2017 at our facility and were followed up for 2 years or more were included. Radiological parameters were measured on whole-spine anteroposterior and lateral radiographs. Revised SRS-22 (SRS-22r) values were also recorded. Coronal trunk imbalance was defined as a deviation of ≥2.0 cm between the C7PL and the central sacral vertical line. Patients with and without coronal trunk imbalance at 2 years after surgery were defined as D (+) (decompensation type) and D (-), respectively. Mean SRS-22r values, including function, pain, self-image, mental health, and subtotal were compared between the D (+) and D (-) groups. Logistic regression analysis was performed to detect the preoperative factors related to D (+) using predictors, including curve type, maximum Cobb angle, and coronal trunk imbalance. RESULTS: At 2 years after surgery, the D (+) group had a significantly lower self-image in the domain of SRS-22r scores compared with the D (-) group. Preoperative coronal trunk imbalance was significantly related to D (+) but not to significant changes in the postoperative SRS-22 score in any of the SRS-22 domains. CONCLUSIONS: Postoperative C7PL deviation lowers the self-image in patients with AIS. Patients with preoperative coronal trunk imbalance were significantly more likely to be D (+).

Surgical results for cervical spondylotic myelopathy with inconsistent between deep tendon reflex findings and magnetic resonance imaging findings.

BACKGROUND: To evaluate the surgical results of patients with cervical spondylotic myelopathy (CSM) with inconsistency between deep tendon reflex findings and cervical magnetic resonance imaging (MRI) findings and to analyze the differences between patients with good and poor surgical outcomes. METHODS: We evaluated 50 subjects with CSM (30 males, 20 females; mean age: 70.4 years) who underwent posterior surgery and were followed for at least 1 year postoperatively. Matched CSM was defined as a consistent preoperative neurological pattern determined by deep tendon reflex and cervical MRI T2-weighted high-signal intramedullary area or stenosis in the most cranial compression levels. A lack of consistency was classified as unmatched CSM. Recovery rate (RR) according to Japanese Orthopaedic Association (JOA) scoring preoperatively and at 1 year postoperatively were compared between the groups. RESULTS: The matched and unmatched CSM group included 27 subjects (13 males, 14 females; mean age: 68.2 years) and 23 subjects (17 males, 6 females; mean age: 72.8 years), respectively. RR was significantly higher in the matched CSM group (56.1 ± 3.7 % vs 36.8 ± 2.7 %; p = 0.002). Unmatched CSM was significantly associated with a lower RR independently of sex, patient age, surgical procedure, preoperative JOA score, diagnosis levels, and complication of diabetes. CONCLUSIONS: Postoperative JOA score RR was significantly diminished among unmatched CSM patients comprising of 46% of cases. Some patients with unmatched CSM had multiple levels of spinal canal stenosis, foraminal stenosis, and peripheral neuropathy, suggesting that surgical results were poorer than those of matched CSM.

Tips and pitfalls to improve accuracy and reduce radiation exposure in intraoperative CT navigation for pediatric scoliosis: a systematic review.

BACKGROUND CONTEXT: An increasing number of medical centers are adopting an intraoperative computed tomography (iCT) navigation system (iCT-Navi) to provide three-dimensional navigation for pediatric scoliosis surgery. While iCT-Navi has been reported to provide higher pedicle screw (PS) insertion accuracy, it may also result in higher radiation exposure to the patient. What innovations and studies have been introduced to reduce radiation exposure and further improve PS insertion? PURPOSE: Evaluate the level of evidence and quality of papers while categorizing the tips and pitfalls regarding pediatric scoliosis surgery using iCT-Navi. Compare iCT-Navi with other methods, including preoperative CT navigation. STUDY DESIGN: Systematic review. PATIENT SAMPLE: Articles on pediatric scoliosis surgery with iCT-Navi published through to June 2022. OUTCOME MEASURES: PS perforation rate and patient intraoperative radiation dose. METHODS: Following PRISMA guidelines, the Cochrane Library, Google Scholar, and PubMed databases were searched for articles satisfying the criteria of iCT-Navi use and pediatric scoliosis surgery. The level of evidence and quality of the articles meeting the criteria were evaluated according to the guidelines of the North American Spine Society and American Academy of Orthopedic Surgeons, respectively. The articles were also categorized by theme and summarized in terms of PS insertion accuracy and intraoperative radiation dose. The origins and characteristics of five major classification methods of PS perforation grade were summarized as well. RESULTS: The literature search identified 811 studies, of which 20 papers were included in this review. Overall, 513 pediatric scoliosis patients (381 idiopathic, 44 neuromuscular, 39 neurofibromatosis type 1, 28 congenital, 14 syndromic, seven other) were evaluated for PS perforations among 6,209 iCT-Navi insertions. We found that 232 (3.7%) screws were judged as major perforations (G2 or G3), 55 (0.9%) screws were judged as dangerous deviations (G3), and seven (0.1%) screws were removed. There were no reports of neurovascular injury caused by PSs. The risk factors for PS perforation included more than six vertebrae distance from the reference frame, more than nine consecutive insertions, upper thoracic level, thinner pedicle, upper instrumented vertebra proximity, short stature, and female. The accuracy of PS insertion did not remarkably decrease when the radiation dose was reduced to 1/5 or 1/10 by altering the iCT-Navi protocol. CONCLUSIONS: iCT-Navi has the potential to reduce PS perforation rates compared with other methods. The use of low-dose radiation protocols may not significantly affect PS perforation rates. Although several risk factors for PS perforation and measures to reduce radiation dose have been reported, the current evidence is limited by a lack of consistency in classifying PS perforation and evaluating patient radiation dose among studies. The standardization of several outcome definitions is recommended in this rapidly developing field.

How much residual deformity is acceptable according to SRS-22r and satisfaction scores after posterior spinal fusion for Lenke type 1 and 2 curves in adolescent idiopathic scoliosis?

OBJECTIVE: In recent years, it has become possible to predict postoperative correction and residual deformity in adolescent idiopathic scoliosis (AIS) surgery based on the technique used and extent of fixation. However, the recommended degree of correction has not yet been established. In this study, the authors aimed to clarify the extent to which a residual postoperative deformity would be acceptable according to Scoliosis Research Society (SRS)-22r and satisfaction scores after AIS surgery. METHODS: Overall, 92 patients who underwent posterior spinal fusion for Lenke type 1 or 2 AIS were retrospectively included. The Patient Acceptable Symptom State (PASS) cutoff values for each SRS-22r domain were calculated using receiver operating characteristic (ROC) curves to obtain predictive values of treatment satisfaction 2 years after surgery. Multivariate logistic regression analysis was performed with deformity parameters and demographic data as explanatory variables, and achieving the PASS cutoff value of each SRS-22r domain and treatment satisfaction were objective variables. Cutoff values were calculated using ROC analysis. RESULTS: The PASS cutoff values for SRS-22r domains were 3.69 (area under the ROC curve [AUC] 0.86) for self-image, 4.25 (AUC 0.82) for mental health, and 4.22 (AUC 0.82) for the subtotal. The residual main thoracic Cobb angle was not remarkably related to SRS-22r or treatment satisfaction. The residual thoracolumbar/lumbar (TL/L) Cobb angle was significantly associated with treatment satisfaction, with a cutoff value of 12.5° (AUC 0.75). The parameters of deformity that were significantly associated with achieving the PASS cutoff value for self-image were the TL/L Cobb angle and main thoracic apical vertebral translation, although their respective AUCs were < 0.7. CONCLUSIONS: In patients with Lenke type 1 and 2 AIS, the residual postoperative TL/L Cobb angle was significantly associated with achieving the PASS cutoff values for self-image and treatment satisfaction. Satisfaction with treatment was more likely when the TL/L Cobb angle was ≤ 12.5°.

Comparison of differences and random errors in pedicle diameter measurements between MRI and CT: observational study of 315 pedicles in Lenke type 1 adolescent idiopathic scoliosis patients.

BACKGROUND CONTEXT: Posterior spinal fusion with pedicle screws is commonly used for the treatment of adolescent idiopathic scoliosis (AIS). To reduce radiation exposure, methods other than computed tomography (CT) are desirable for preoperative determination of pedicle diameter. PURPOSE: Investigate the differences between magnetic resonance imaging (MRI) and CT measurements of pedicle diameter. STUDY DESIGN: Cross-sectional research. PATIENT SAMPLE: Twenty-one AIS Lenke type 1 patients (19 female and 2 males, mean age at surgery: 15.4 years) who underwent posterior spinal fusion between April 2009 and October 2019. OUTCOME MEASURES: Gap between CT and MRI pedicle diameters. METHODS: The inner and outer diameters of the right and left pedicles from T1 to L3 were measured separately by two spine surgeons for statistical comparisons. RESULTS: The respective minimum and maximum CT-MRI values were -3.7 mm and 4.7 mm for inner diameter and -4.6 mm and 5.3 mm for outer diameter. Regarding inter-examiner error, the probability of a 2 mm difference in measurement was less than 5% for both modalities. The probability of a 1 mm difference was also less than 5%, and that of a 3 mm or more difference was 2.1% for the inner diameter and 2.9% for the outer diameter. Whereas low body weight was significantly associated with measurement differences, pedicle laterality was not. CONCLUSIONS: MRI does not have the reliability to measure pedicle size in AIS patients at present. However, with advancements in image processing technology, the accuracy of pedicle size measurement by MRI may soon improve.

Pre-operative angle of trunk rotation in prone position estimates postoperative correction results.

ABSTRACT: This study investigated whether postoperative rotational deformity in adolescent idiopathic scoliosis patients could be predicted by prone-position pre-operative angle of trunk rotation (ATR).Surgical rib hump correction is performed with the patient in a prone position. However, the association between pre-operative ATR in the prone position and postoperative ATR results is unknown.Thirty-four consecutive patients who underwent skip pedicle screw fixation for Lenke type 1 or 2 adolescent idiopathic scoliosis were retrospectively reviewed. All subjects were followed for a minimum of 1 year. ATR measurements were taken for the standing-flexion position with a scoliometer before surgery and at 1 year afterward. Pre-operative measurements were also taken for the prone position. Correlations between pre- and postoperative ATR were calculated by means of Pearson correlation coefficient. Associations between the correction angle from the standing-flexion position to prone position and postoperative standing-flexion correction angle were determined by linear regression analysis.Pre- and postoperative ATR for the standing-flexion position showed a moderate association (r = 0.64, P < .01). A similar correlation was seen for pre-operative prone-position ATR and postoperative standing-flexion ATR (r = 0.56, P < .01). In linear regression analysis, there was significant proportional error between the correction angle from the standing-flexion position to prone position and postoperative standing-flexion correction angle (ß = 0.40, P < .01).In conclusion, pre-operative ATR in either standing-flexion or prone position and postoperative standing-flexion ATR displayed moderate associations. Linear regression analysis revealed that ATR correction angle could be estimated by calculating the correction gains of 0.4° per 1° of correction angle in the prone position.

Long-Term Surgical Results of Skip Pedicle Screw Fixation for Patients with Adolescent Idiopathic Scoliosis: A Minimum-Ten-Year Follow-Up Study.

Skip pedicle screw fixation for adolescent idiopathic scoliosis (AIS) requires fewer screws and can reduce the risk of neurovascular injury as compared with segmental pedicle screw fixation. However, the long-term impact of screw number reduction on correction and clinical results is unclear. This study examined the 10-year post-operative outcomes of skip pedicle screw fixation for patients with AIS. We reviewed the outcomes of 30 patients who underwent skip pedicle screw fixation for AIS. Radiological and clinical findings were assessed before and immediately, 2 years, and 10 years after surgery in the remaining 25 patients. The mean Cobb angle of the main curve preoperatively and immediately, 2 years, and 10 years post-operatively was 59.4°, 23.4°, 25.8°, and 25.60°, respectively, and was significantly improved at all post-surgical time points (all p < 0.001). The mean correction rate immediately after surgery was 60.8%, and the correction loss rate at the observation end point was 4.8%. The Cobb angle of the lumbar curve was significantly improved immediately after surgery, and the correction persisted until 10 years post-operatively. Remarkable gains were observed for most Scoliosis Research Society-22 patient questionnaire sub-scores at the final follow-up versus preoperative assessments. In conclusion, good correction of the AIS deformity by skip pedicle screw fixation was well maintained over a long follow-up period of 10 years, with clinically meaningful gains in Society-22 patient questionnaire sub-scores.

Does Main Curve Flexibility Affect Screw Insertion Accuracy Using a CT-based Navigation System in Adolescent Idiopathic Scoliosis Surgery?

STUDY DESIGN: A retrospective single-center and single-surgeon study. OBJECTIVE: This study investigated the screw perforation rate according to main curve flexibility in pedicle screw fixation using a computed tomography (CT) guidance for adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND: The authors have been using a CT-based navigation system during pedicle screw insertion for AIS to avoid serious neurovascular or visceral structure injury but suspect that high main curve flexibility may account for some breaches. DATA: Seventy-two consecutive patients with AIS Lenke type 1 or 2 who had undergone pedicle screw fixation using a CT-based navigation system between February 2008 and April 2018 were retrospectively reviewed. MATERIALS AND METHODS: The authors evaluated the perforation rate of pedicle screws inserted into the main thoracic curve between the upper-end and lower-end vertebrae for factors associated with screw violations using multivariate logistic regression mixed models. RESULTS: A total of 723 pedicle screws were inserted into the T4-T12 vertebrae with the aid of CT-based navigation. The respective grade 3 perforation rates according to main curve flexibility were 0%-30%: 3.2%; 30%-55%: 1.1%; 55%-75%: 5.2%; and 75%-100%: 5.5%. Main curve flexibility of ≥55% was significantly associated with grade 3 screw perforations (P=0.02). CONCLUSIONS: Main curve flexibility of ≥55% was significantly related to screw violation in AIS surgery. Greater care is thus advised for screw insertion using CT navigation in AIS with main curve flexibility ≥55%.

Factors leading to postoperative pain in adolescent idiopathic scoliosis patients including sagittal alignment and lumbar disc degeneration.

PURPOSE: This study examined for factors contributing to postoperative pain in adolescent idiopathic scoliosis (AIS), including those of sagittal alignment and lumbar disc degeneration. METHODS: A total of 101 consecutive patients who underwent posterior spinal fusion for AIS and who were followed for a minimum of 2 years were included in this investigation. We assessed Lenke curve type, age, Risser grade, body mass index (BMI), radiographic parameters, lumbar disc degeneration, correction rate, number of fused vertebrae, lowest instrumented vertebra, preoperative SRS-22r survey mental health score, and pre- and postoperative SRS-22r survey pain scores. Univariate and multivariate general linear models were employed to identify factors associated with pain 2 years after AIS surgery. RESULTS: In multivariate analysis, patients with a lower preoperative pain score (i.e. higher pain) (P < 0.01) or higher postoperative T5-12 kyphotic angle (P = 0.02) had a worsened pain score 2 years after surgery. There were no remarkable differences for Lenke curve type, age, BMI, coronal radiographic parameters, lumbar disc degeneration, correction rate, number of fused vertebrae, or lowest instrumented vertebra. Higher preoperative Risser grade (P = 0.01) and lower preoperative SRS-22r mental health score (P < 0.01) were significantly related to a diminished preoperative SRS-22r pain score. CONCLUSION: While preoperative lumbar disc degeneration was not associated with pre- or postoperative pain in AIS, higher preoperative pain and higher postoperative T5-12 kyphotic angle had significant associations with augmented postoperative pain. Higher preoperative pain was related to increased Risser grade and lower mental health score. These slides can be retrieved under Electronic Supplementary Material.

Upper instrumented vertebra to the right of the lowest instrumented vertebra as a predictor of an increase in the main thoracic curve after selective posterior fusion for the thoracolumbar/lumbar curve in Lenke type 5C adolescent idiopathic scoliosis: multicenter study on the relationship between fusion area and surgical outcome.

OBJECTIVE: Unfused main thoracic (MT) curvatures occasionally increase after selective thoracolumbar/lumbar (TL/L) fusion. This study sought to identify the predictors of an unacceptable increase in MT curve (UIMT) after selective posterior fusion (SPF) of the TL/L curve in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS). METHODS: Forty-eight consecutive patients (44 females and 4 males, mean age 15.7 ± 2.5 years, range 13-24 years) with Lenke type 5C AIS who underwent SPF of the TL/L curve were analyzed. The novel "Shinshu line" (S-line) was defined as a line connecting the centers of the concave-side pedicles of the upper instrumented vertebra (UIV) and lowest instrumented vertebra (LIV) on preoperative radiographs. The authors established an S-line tilt to the right as S-line positive (S-line+, i.e., the UIV being to the right of the LIV) and compared S-line+ and S-line- groups for thoracic apical vertebral translation (T-AVT) and MT Cobb angle preoperatively, early postoperatively, and at final follow-up. The predictors for T-AVT > 20 mm at final follow-up were evaluated as well. T-AVT > 20 mm was defined as a UIMT. RESULTS: Among the 48 consecutively treated patients, 26 were S-line+ and 22 were S-line-. At preoperative, early postoperative, and final follow-up a minimum of 2 years later, the mean T-AVT was 12.8 mm (range -9.3 to 32.8 mm), 19.6 mm (range -13.0 to 41.0 mm), and 22.8 mm (range -1.9 to 68.7 mm) in the S-line+ group, and 10.8 mm (range -5.1 to 27.3 mm), 16.2 mm (range -11.7 to 42.1 mm), and 11.0 mm (range -6.3 to 26.9 mm) in the S-line- group, respectively. T-AVT in S-line+ patients was significantly larger than that in S-line- patients at the final follow-up. Multivariate analysis revealed S-line+ (odds ratio [OR] 23.8, p = 0.003) and preoperative MT Cobb angle (OR 7.9, p = 0.001) to be predictors of a UIMT. CONCLUSIONS: S-line+ was defined as the UIV being to the right of the LIV. T-AVT in the S-line+ group was significantly larger than in the S-line- group at the final follow-up. S-line+ status and larger preoperative MT Cobb angle were independent predictors of a UIMT after SPF for the TL/L curve in patients with Lenke type 5C AIS. Surgeons should consider changing the UIV and/or LIV in patients exhibiting S-line+ during preoperative planning to avoid a possible increase in MT curve and revision surgery.

Correlation of Lower Instrumented Vertebra With Spinal Mobility and Health-related Quality of Life After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis.

STUDY DESIGN: This is a retrospective single-center and single-surgeon study. OBJECTIVE: We investigated the correlation between lower instrumented vertebra (LIV) and spinal mobility 2 years after posterior spinal fusion with pedicle screws for adolescent idiopathic scoliosis (AIS) for optimal LIV selection. SUMMARY OF BACKGROUND: Spinal motion can become limited in scoliosis patients who undergo posterior spinal fusion. However, few reports exist on spinal mobility after posterior spinal fusion for AIS and the relationship between the LIV and mobility is unknown. We hypothesize that mobility limitation increases as the LIV is moved inferiorly. DATA: Of 72 consecutive patients who received posterior spinal fusion using pedicle screws for AIS between October 2009 and August 2015, 66 patients (5 male and 61 female, mean age: 14.9 y) were enrolled. MATERIALS AND METHODS: In total, 66 patients were retrospectively reviewed after stratification according to LIV level. Follow-up rate was 91.7%. Patients were examined for the fingertip-to-floor distance (FFD) before and 2 years after surgery. FFD was measured from the tips of the middle fingers to the floor with the barefoot subject bent maximally forward and the feet together and knees straight. Clinical outcome was assessed using Scoliosis Research Society-22 patient questionnaire (SRS-22r) scores and a visual analog scale for low back pain before and at 2 years postoperatively. RESULTS: The median number of fused vertebrae was 9 (range: 4-15). The LIV was T11-12 in 15 patients, L1 in 11 patients, L2 in 10 patients, and L3 in 30 patients. The median decrease in FFD according to LIV at 2 years after surgery was T11-12: 0 cm, L1: 0 cm, L2: 5.5 cm, and L3: 10 cm. Thus, limited FFD became significantly more severe as the LIV was moved downwards (P<0.01). There were no significant correlations between limited FFD and SRS-22r or pain visual analog scale scores at 2 years postoperatively. CONCLUSIONS: FFD became significantly more restricted as the LIV was moved inferiorly but clinical results appeared unaffected by limited FFD.

Ten-Year Results of Reconstruction for Rheumatoid Cervical Spine Lesions and Occurrence Factor of Subaxial Subluxation.

Study Design: Retrospective chart review. Purpose: This study evaluated long-term surgical outcomes of computer-assisted reconstruction using transarticular or cervical pedicle screws for cervical spine lesions caused by advanced rheumatoid arthritis (RA). Overview of Literature: We routinely employ C1-C2 transarticular and cervical pedicle screw instrumentation to reconstruct advanced and unstable RA cervical lesions. However, few reports are available on the long-term results of surgical reconstruction for rheumatoid cervical disorders, particularly regarding cervical pedicle screw fixation. Methods: Six subjects (all female) with RA cervical lesions who underwent atlantoaxial or occipitocervical fixation and were followed for at least 10 years were retrospectively studied. A frameless, stereotactic, optoelectronic, computed tomography-based image guidance system was used for correct screw placement. Variables including the Japanese Orthopaedic Association score, EuroQol, Ranawat value, and C2-C7 angle before and 2, 5, and 10 years after surgery were assessed along with the occurrence of subaxial subluxation (SAS). Results: Mean age at initial surgery was 58.2±7 years (range, 51-68 years), and mean follow-up period was 141±11 months (range, 122-153 months). Lesions included atlantoaxial subluxation (AAS, n=2) and AAS+vertical subluxation (n=4). Mean C2-C7 lordotic angle before and 2, 5, and 10 years after surgery was 20.1°±6.1°, 21.0°±4.0°, 18.8°±4.7°, and 17.8°±5.3°, respectively. SAS did not occur in cases maintaining the C2-C7 lordotic angle. In two cases where the C2-C7 lordotic angle declined from 5 years postoperatively, SAS occurred at the C2-C3 level in one and at the C4-C5 level in the other, both of which required reoperation. Conclusions: Patients with rheumatoid cervical lesions who undergo atlantoaxial or occipitocervical fixation using C1-C2 transarticular or pedicle screws carry a risk of SAS for up to 10 years postoperatively, which may require reoperation.

Two-stage posterior spinal fusion for early-onset scoliosis: Two case reports.

RATIONALE: Fusionless techniques for early-onset scoliosis (EOS) have evolved to allow near-normal growth while maintaining the correction achieved during the initial surgery. However, such procedures require repeated surgeries and have increased complication rates. We have developed a 2-stage fusion technique using pedicle screws for EOS to reduce patient burden and complication risk. This series describes the clinical and radiological features of 2 patients with EOS who received 2-stage posterior spinal fusion. This surgical method for EOS represents the first of its kind. PATIENT CONCERNS: Case 1 was a 10-year-old girl who was diagnosed as having scoliosis with Prader Willi syndrome at the age of 2 years. Her preoperative major curve Cobb angle was 100 degrees at age 10 years. Case 2 was an 11-year-old boy who was found to have scoliosis with 22q11.2 deletion syndrome at the age of 4 years. His preoperative major curve Cobb angle was 77 degrees at age 11 years. DIAGNOSIS: Whole-spine radiographs were performed to diagnose scoliosis. INTERVENTIONS: Both patients received 2-stage posterior spinal fusion. OUTCOMES: Postoperative Cobb angle of the major curve improved to 46 and 48 degrees, respectively. Thoracic height respectively improved from 160 and 148 mm before surgery to 206 and 211 mm at final follow-up. Surgical outcome as evaluated by Scoliosis Research Society-22 patient questionnaires revealed acceptable results without any severe complications. LESSONS: Based on the present case report, 2-stage posterior spinal fusion for EOS achieves good radiological and clinical outcomes without severe complications.

Prediction of Spontaneous Lumbar Curve Correction After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis Lenke Type 1 Curves.

STUDY DESIGN: This is a retrospective single-center and single-surgeon study. OBJECTIVE: The present study examined for preoperative parameters having the highest correlation with compensatory thoracolumbar/lumbar (TL/L) curve correction 2 years after surgery in adolescent idiopathic scoliosis (AIS) patients with Lenke type 1 curves. SUMMARY OF BACKGROUND: Several parameters have been considered to evaluate the flexibility of compensatory TL/L curve in AIS patients with Lenke type 1 curves. However, the imaging position with the strongest correlation with postoperative spontaneous TL/L curve correction is unknown. DATA: In total, 37 patients with AIS Lenke type 1 curves who had undergone skip pedicle screw fixation were followed for a 2-year period were enrolled. MATERIALS AND METHODS: TL/L Cobb angles measured at the standing posteroanterior view, supine position, supine position with maximum bending, supine position with traction, prone position, and prone-push position were determined before surgery. Using TL/L Cobb angles determined 2 years postoperatively, correlations between preoperative and postoperative Cobb angles were calculated for each position using the Spearman rank-correlation coefficient, linear regression analysis, and paired t tests. RESULTS: Mean preoperative mean±SD TL/L Cobb angle was significantly improved from 31±9 to 13±8 degrees at the study end point. In analyses of correlations between postoperative TL/L Cobb angle and preoperative parameters, the supine position with traction was most strongly associated with TL/L curve correction rate at 2 years after surgery (r=0.72; P<0.01), with paired t tests revealing a significant mean difference of 3.1 degrees. CONCLUSIONS: Preoperative Cobb angle evaluated at the supine position with traction had the strongest correlation with spontaneously corrected TL/L curve Cobb angle after selective thoracic fusion for AIS Lenke type 1 curves. Accordingly, it may be sufficient to evaluate TL/L curve correction at this position only to reduce radiation exposure and operative time.

How Much Surface Registration Accuracy is Required Using Ct-based Navigation System in Adolescent Idiopathic Scoliosis Surgery?

STUDY DESIGN: Retrospective, single-center, single-surgeon study. OBJECTIVE: This study investigated screw perforation rate according to surface registration accuracy in pedicle screw fixation using a CT-based navigation system for adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: Posterior spinal fusion for scoliosis correction using pedicle screws is widely adopted but carries a risk of serious neurovascular or visceral structure events. To attempt to avoid these complications, we have been using a computed tomography (CT)-based navigation system during screw insertion, although insufficient surface registration accuracy may be a reason for some screw perforations. METHODS: We evaluated 116 AIS patients (9 male and 107 females; mean±standard deviation age: 15.2±2.3 y) who had received pedicle screw fixation guided by a CT-based navigation system between August 2007 and December 2017. Screw perforation rate was evaluated in relation to surface registration accuracy and cut-off values were determined by receiver operating characteristic (ROC) curves. RESULTS: A total of 1553 pedicle screws were inserted into T2-L4 vertebrae using CT-based navigation system. The respective overall perforation rates for grade 2 or 3 and grade 3 perforations by surface registration accuracy were 0.2 mm: 0% and 0%; 0.3 mm: 3.5% and 0%; 0.4 mm: 3.5% and 0.8%; 0.5 mm: 8.0% and 3.5%; 0.6 mm: 6.7% and 2.7%; 0.7 mm: 8.9% and 3.8%; 0.8 mm: 9.3% and 6.7%; and 0.9 mm: 9.3% and 4.7%. ROC curve analysis revealed a cut-off surface registration accuracy of 0.5 mm. The major screw perforation rate for a surface registration accuracy of ≥0.5 mm was significantly higher than that for <0.5 mm (P<0.01). CONCLUSIONS: Analysis of screw perforation rate according to surface registration accuracy demonstrated a clinical cut-off of 0.5 mm. Thus, surface registration accuracy should optimally be <0.5 mm for scoliosis surgery with CT-based navigation system.

Determination of optimal screw number based on correction angle for main thoracic curve in adolescent idiopathic scoliosis.

BACKGROUND: Reducing the number of screw insertions while maintaining good clinical outcomes can improve the efficiency and cost-effectiveness of scoliosis surgery. However, the optimal minimum number of pedicle screws remains unclear. This study searched for factors to estimate the fewest number of pedicle screws required between end vertebrae in relation to preoperative main thoracic curve flexibility. METHODS: Sixty-nine subjects (4 male and 65 female, mean age: 14.8 ± 2.5 years) who underwent skip pedicle screw fixation for Lenke type 1-4 or 6 curves and were followed for at least 1 year were enrolled. Intervention technique was selected according to the size and flexibility of the preoperative main thoracic curve. Surgery-related variables included pedicle screw number, rod material and diameter, and extent of Ponte osteotomy. The effect on postoperative correction angle (i.e., the difference between the preoperative supine position maximum bending and postoperative standing Cobb angles of the main thoracic curve) according to surgical intervention technique was estimated using multiple linear mixed regression models with the preoperative supine position maximum bending correction angle (i.e., the difference between the standing preoperative and supine position maximum bending Cobb angles) as a random effect. RESULTS: The preoperative maximum bending correction angle was 8-42° and had a moderate negative correlation with postoperative correction angle (r = -0.65, P < 0.01). Multivariate analysis revealed a 1.7° (95% CI 0.7-2.6; P < 0.01) correction gain per single-screw insertion and a 1.8° (95% CI 0.5-3.1; P < 0.01) gain per intervertebral level in Ponte osteotomy. CONCLUSIONS: The number of pedicle screws necessary to correct main thoracic adolescent idiopathic scoliosis curves can be estimated by calculating correction gains of 1.7° per pedicle screw and 1.8° per Ponte osteotomy intervertebral level. Based on these results, it may be possible to reduce invasiveness and cost for patients requiring a smaller degree of correction.

Can surgery for adolescent idiopathic scoliosis of less than 50 degrees of main thoracic curve achieve good results?

BACKGROUND: It is generally recognized that the main thoracic curve Cobb angle threshold for surgical correction is approximately 50 degrees in patients with adolescent idiopathic scoliosis (AIS). Although AIS with a Cobb angle of <50 degrees is sometimes treated surgically to improve cosmesis, the precise outcomes are unclear. This study analyzed the postoperative results for AIS with a main thoracic curve of 50 degrees. METHODS: Thirty-nine consecutive patients with Lenke type 1-2 curves underwent posterior spinal fusion for AIS. These subjects were divided into the <50 degrees of main thoracic curve group (n = 14) and the ≥50 degrees group (n = 25). Clinical and radiographic data were compared. RESULTS: The mean Cobb angle of the main thoracic curve before and at 2 years after surgery for the <50 degrees and ≥50 degrees groups was 44.5 and 60.3 degrees (p < 0.001) and 14.0 and 19.5 degrees (p = 0.016), respectively. Preoperatively, both groups had comparable Scoliosis Research Society-22 (SRS-22) scores (all p > 0.05). Patients with a Cobb angle of <50 degrees displayed significantly milder postoperative pain (4.7 vs. 4.3, p = 0.031), with no remarkable differences in other SRS-22 domain scores. These patients also had a significantly shorter operative time (194 vs. 235 min, p = 0.021) and fused level (9.2 vs. 10.8 vertebrae, p = 0.006) along with similar correction rate (68.1 vs. 65.8%, p = 0.622) and blood loss volume (932 vs. 1009 ml, p = 0.715). CONCLUSIONS: Surgical correction of AIS with <50 degrees of main thoracic curve may less invasively achieve results that are comparable with those for AIS with 50 degrees or more, including improvements in self-image.