All-pedicle-screw versus hybrid hook-screw instrumentation for posterior spinal correction surgery in adolescent idiopathic scoliosis: a curve flexibility matched-pair study

Hybrid vs all pedicle screws constructs in adolescent idiopathic scoliosis: a metaanalysis of clinical and radiological outcomes

BACKGROUND

Adolescent idiopathic scoliosis (AIS) affects around 1 to 3% of young individuals, leading to spinal deformities typically exceeding a Cobb angle of 10 degrees without congenital or neuromuscular causes. Advances in treatment now include various surgical techniques such as posterior fusion utilizing all-pedicle screw constructs or hybrid constructs.

METHODS

PubMed, Cochrane, and Google Scholar (pages 1-20) were searched up until February 2024. Comparative studies in which the cohort was separated into two groups (HC and PSC) were included. Data consisting of, surgery-related outcomes, sagittal radiographic outcomes, coronal radiographic outcomes, and patient-reported outcomes, was extracted and compared.

RESULTS

Twenty-eight studies including 3435 patients were included. Higher rates of complications (Odds-Ratio = 1.99, p < 0.00001) and reoperations (Odds-Ratio = 2.82, p < 0.00001) were seen in the hybrid group. Better radiographic coronal correction was seen in the PSC group in both the major curve (Mean Difference = 5.97, p < 0.00001) and the secondary curve (Mean Difference = - 10.73, p < 0.0001). However, restoration of sagittal alignment was better in the HC group when assessing thoracic kyphosis (Mean Difference = 2.97, p = 0.02) and lumbar lordosis (Mean Difference = 3.17, p = 0.005).

CONCLUSION

While all-pedicle screw constructs demonstrated greater stability in AIS compared to hybrid constructs, resulting in reduced rates of reoperations and complications, as well as improved correction of major and secondary curves, they were unable to fully restore optimal sagittal alignment.

Loss of correction in cubitus varus deformity after osteotomy

We aimed to investigate the rate of loss of correction and the factors thereof in pediatric patients undergoing osteotomy for treatment of cubitus varus deformity.Between July 2008 and July 2017, we treated 30 patients who underwent osteotomy for cubital varus. We compared the preoperative and postoperative clinical and imaging findings, including the H-Cobb and Baumman angles, in all patients. Postoperative evaluation was performed by telephonic interviews.Our patients consisted of 17 males and 13 females. The mean age was 75 months. At the first follow-up, approximately 80% of patients had experienced a loss of correction of the humerus-cobb angle (H-Cobb angle); at the second follow-up, the incidence was 83%. Meanwhile, 57% and 43% of patients experienced a loss of correction of the Baumman angle at the first and second follow-ups, respectively. The average interval between the first and second follow-ups was 24 days, and the mean loss in the H-Cobb angle was 2.4°. There was a significant difference between the H-Cobb angles as measured before and after surgery (P < .05). There was no significant difference between the H-Cobb angles of the affected side and the contralateral healthy elbow at the third postoperative follow-up; however, there was a significant difference between the Baumman angle between before and after surgery (P < .05). The Baumman angles as measured at the second and third postoperative follow-ups differed significantly from those of the contralateral healthy elbow joint. According to the survival curve analysis, the median survival times of the H-Cobb and Baumman angles were 27 and 34 months, respectively.The postoperative loss of the 2 angles occurred mainly during the first and second follow-up periods. Therefore, patient follow-up is particularly important in the period directly following the operation. Additional measures may be necessary to avoid rapid angle loss.

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.

Comparative radiological outcomes and complications of sacral-2-alar iliac screw versus iliac screw for sacropelvic fixation

PURPOSE

To compare the outcomes of sacropelvic fixation (SPF) using sacral-2-alar iliac (S2AI) screw with SPF using iliac screw (IS).

METHODS

A comprehensive search of PubMed, EMBASE, Cochrane Central Register of Controlled Trials and Scopus was performed for comparative studies between S2AI and IS for SPF. Two independent investigators selected qualified studies and extracted data indispensably. With 95% confidence intervals (CI), the odds ratio (OR) was applied to dichotomous outcomes and standardized mean difference (SMD) was applied to continuous outcomes for each item.

RESULTS

We included data from thirteen studies involving 722 patients (S2AI, 357 patients; IS, 365 patients). In the pediatric population, the S2AI group had a smaller pelvic obliquity (PO) than the IS group at final follow-up (SMD, - 0.38; 95% CI, - 0.72 to - 0.04). Patients who underwent S2AI screws showed reduced rates of re-operation (S2AI, 13%; IS, 28%), implant failure (S2AI, 12%; IS, 26%) [screw loosening (S2AI, 8%; IS, 20%); screw breakage (S2AI, 2%; IS, 12%)], implant prominence (S2AI, 2%; IS, 14%), pseudarthrosis (S2AI, 3%; IS, 15%), wound infection (S2AI, 8%; IS, 22%) and less blood loss (S2AI, 2035.4 ml; IS, 2708.4 ml).

CONCLUSION

Radiological outcomes indicate an effective maintenance of the correction and arrest of progression of deformity by S2AI, which is equal or better than IS. SPF with S2AI screw has obviously lower incidence of postoperative complications and less blood loss. Given these advantages, the S2AI screw seems to be a beneficial alternative to IS.

A Nomogram to Predict the Occurrence and Development of Postoperative Neck Tilt in Lenke I and II AIS Patients

OBJECTIVE

To investigate the risk factors and to construct a nomogram for the prediction of postoperative neck tilt (PNT) in patients with Lenke I and II adolescent idiopathic scoliosis (AIS).

METHODS

A total of 95 patients with Lenke I and II AIS who underwent posterior segmental spinal instrumentation and fusion between the years 2010 and 2018 (with an average 2-year follow-up) at a single institution were retrospectively investigated. The full spine X-rays of patients were measured preoperatively, postoperatively, and at the final follow-up. Variables were compared between the PNT group (n = 33) and the non-PNT group (n = 62), and univariate and multivariate logistic regressions were performed to identify the independent predictors for the occurrence of PNT. The discrimination and calibration of the nomogram were validated by the receiver operating characteristic curve and calibration curve.

RESULTS

Variables including the preoperative neck tilt, postoperative upper instrumented vertebrae imbalance, postoperative T1 tilt, and decreasing values in the main thoracic curve (ΔMTC) minus decreasing values in the proximal thoracic curve (ΔPTC) (ΔMTC - ΔPTC) were identified as the predictors for the nomogram. The area under the receiver operating characteristic curve was 0.900 (95% confidence interval, 0.857-0.932). Meanwhile, the calibration curve revealed good agreement, and the Hosmer and Lemeshow test determined that the model was well fitted.

CONCLUSIONS

Preoperative neck tilt, postoperative upper instrumented vertebrae imbalance, postoperative T1 tilt, and ΔMTC-ΔPTC are predictors for the nomogram. The nomogram can provide surgeons with a simple and effective tool to predict the occurrence and development of patients with PNT in Lenke I and II AIS.

Large Difference Between Proximal Junctional Angle and Rod Contouring Angle is a Risk Factor for Proximal Junctional Kyphosis

OBJECTIVE

To assess the role of the difference between the proximal junctional angle (PJA) and rod contouring angle (RCA) (PJA-RCA) in the development of postoperative proximal junctional angle (PJK) in Lenke I and II adolescent idiopathic scoliosis (AIS) patients.

METHODS

We performed a retrospective analysis of 84 Lenke I and II AIS patients who underwent posterior segmental spinal instrumentation and fusion between 2012 and 2018 (minimum follow-up of 1.5 years and an average follow-up of 2 years) at a single institution. The full-spine x-ray films taken at the preoperative, postoperative, and final follow-ups were measured for each patient. The radiographic parameters were compared between the PJK and non-PJK groups, and binary logistic regression with forward elimination (conditional) was also performed to identify the risk factors for the occurrence of PJK.

RESULTS

Among the 84 patients (mean age: 14.63 ± 1.33 years), the overall incidence of PJK was 23.81%. The PJK group showed a larger preoperative pelvic incidence (55.66° ± 8.66° vs. 50.29°±8.27°, P = 0.045), thoracic kyphosis (TK) (32.44° ± 5.60° vs. 27.19° ± 5.14°, P = 0.007) and sagittal vertical axis (SVA) (40.99 ± 21.82 mm vs. 18.13 ± 28.64 mm, P = 0.013) than the non-PJK group. Postoperatively, the PJK group showed a larger decrease in the TK (-10.62° ± 3.19° vs. -5.56° ± 1.17°, P < 0.001) and SVA (-24.28 ± 18.22 mm vs. -10.83 ± 15.02 mm, P = 0.007). In addition, the PJK group had significantly larger postoperative PJA (9.83° ± 2.64° vs. 5.77° ± 3.06°, P < 0.001) and postoperative PJA-RCA (6.56° ± 3.69° vs. 1.55° ±3.32°, P < 0.001). The proportion of patients with a PJA-RCA value greater than 5° was significantly larger in the PJK group (65.00% vs. 18.75%, P < 0.001). At the last follow-up, the PJK patients had significantly larger TK (35.11° ± 5.51° vs. 26.53° ± 4.71°, P < 0.001) and SVA (22.83 ±23.12 mm vs. 3.46 ±26.24 mm, P = 0.038). Binary logistic regression analysis showed that decreases in TK and postoperative PJA-RCA were the primary contributors to PJK in patients with AIS.

CONCLUSIONS

Large postoperative PJA-RCA and decreased TK are risk factors for PJK in Lenke I and II AIS patients, especially those with PJA-RCA greater than 5°, and the occurrence of PJK should be highly considered.

The substantiation of the elastic-viscoplastic model of the human spine for modeling the correction process of kyphoscoliotic deformation

PURPOSE

The relevance of the problem is caused by an increase in the number of spine-related diseases among children, including scoliosis. Currently, there are no methodologies for the treatment of scoliosis, which ensure an unambiguous positive result. The purpose of the article is to justify the spinal model as an elastic viscoplastic body for further mathematical modeling of the process of spine correction and search for its optimal conditions.

METHODOLOGY

The leading approach to the study of this problem is the development of techniques for the surgical treatment of deformities of the vertebral column with the aid of an external fixation device for the spine, providing for a rigid connection of the elements of the apparatus with each other and with the spine. The rigid connection between the elements of the external fixation device increases the degree of static indeterminacy of the design, which leads to the occurrence of additional dangerous stresses in the details of the apparatus and in the vertebrae. The control actions in such devices do not provide an adequate result for the process of correction of the vertebral column.

RESULTS

The main result is the substantiation of the spine model as an elastic viscoplastic body. This will allow more detailed consideration of the medical and biological features of the spine and the physical and mechanical properties of human bone and soft tissues. The proposed model will allow developing an adaptive design of the device, taking into account specific features of the organism and more effectively managing the correction process.

VALUE

The materials of the article can be useful for scientists, doctors and specialists in conducting scientific research on the problem of spine deformation correction and the development of appropriate technical means.

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

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To 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 DATA

PS 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.

METHODS

Two 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.

RESULTS

There 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).

CONCLUSIONS

In 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 EVIDENCE

Level III.

Pedicle screw versus hybrid instrumentation in adolescent idiopathic scoliosis: A systematic review and meta-analysis with emphasis on complications and reoperations

BACKGROUND

Incidence of complications and reoperations between pedicle screw (PS) and hybrid instrumentations (HI) are still controversial in adolescent idiopathic scoliosis (AIS) patients. A systematic review and meta-analysis were performed to compare overall complications, reoperations, and radiographic outcomes between the 2 constructs.

METHODS

Strictly followed the PRISMA 2009 guidelines, the MEDLINE, EMBASE, and the Cochrane Library databases were used to search for literatures up to April 2016, addressing PS versus HI in AIS patients. The Newcastle-Ottawa scale was adopted to assess the quality of the studies. Data on complications, reoperations, Cobb angle of major curve, thoracic kyphosis, and proximal junctional measurement were extracted from the included studies. RevMan 5.3 and SPSS 21.0 were used for statistical analysis.

RESULTS

Twenty-four case-control studies with a total of 3042 AIS patients (1582 PS, 1460 HI) were included, consisting of 1 randomized controlled trial, 1 prospective study, and 22 retrospective studies. Decreased overall complications (95% CI 0.42-0.87, P = .007; I = 38%) and reoperations (95% CI 0.22-0.62, P = .0001; I = 0%) were found in PS group compared with HI group. As regard to reasons for reoperations, increased incidence of pseudarthrosis (P = .005), dislodged instrumentation (P = .005), and deep infection (P = .016) occurred in HI group. PS group achieved a better coronal correction (95% CI -7.06 to -4.54, P < .00001; I = 34%), but HI group was more powerful in restoring thoracic kyphosis (95% CI -7.88 to -3.70, P < .00001; I = 60%), and no significant differences were found in proximal junctional measurement (95% CI -0.88 to 1.54, P = .59; I = 0%) between the 2 constructs.

CONCLUSION

Compared with hybrid instrumentation, pedicle screw construct provides better coronal correction but less thoracic kyphosis restoring, with decreased incidence of overall complications and reoperations in AIS patients. As regard to the pedicle screw construct, the most common reasons for reoperation are malposition, deep infection, pseudarthrosis, and prominent implant.

Could CCI or FBCI Fully Eliminate the Impact of Curve Flexibility When Evaluating the Surgery Outcome for Thoracic Curve Idiopathic Scoliosis Patient? A Retrospective Study

Purpose

To clarify if CCI or FBCI could fully eliminate the influence of curve flexibility on the coronal correction rate.

Methods

We reviewed medical record of all thoracic curve AIS cases undergoing posterior spinal fusion with all pedicle screw systems from June 2011 to July 2013. Radiographical data was collected and calculated. Student t test, Pearson correlation analysis and linear regression analysis were used to analyze the data.

Results

60 were included in this study. The mean age was 14.7y (10-18y) with 10 males (17%) and 50 females (83%). The average Risser sign was 2.7. The mean thoracic Cobb angle before operation was 51.9°. The mean bending Cobb angle was 27.6° and the mean fulcrum bending Cobb angle was 17.4°. The mean Cobb angle at 2 week after surgery was 16.3°. The Pearson correlation coefficient r between CCI and BFR was -0.856(P<0.001), and between FBCI and FFR was -0.728 (P<0.001). A modified FBCI (M-FBCI) = (CR-0.513)/BFR or a modified CCI (M-CCI) = (CR-0.279)/FFR was generated by curve estimation has no significant correlation with FFR (r=-0.08, p=0.950) or with BFR (r=0.123, p=0.349).

Conclusions

Fulcrum-bending radiographs may better predict the outcome of AIS coronal correction than bending radiographs in thoracic curveAIS patients. Neither CCI nor FBCI can fully eliminate the impact of curve flexibility on the outcome of correction. A modified CCI or FBCI can better evaluating the corrective effects of different surgical techniques or instruments.

Loss of correction in spinal cord injury-related scoliosis after pedicle screw fixation

PURPOSE

Spinal cord injury (SCI) in the pediatric population is an infrequent but clinically important disease to scoliosis surgeons. Spinal deformity after SCI is extremely common and almost uniformly develops in patients being injured before the growth spurt. Most treatment paradigms extrapolate management from both the adult literature as well as adolescent idiopathic scoliosis data. Since these patient populations are different in many respects, we sought out to investigate the rates of loss of correction over time as well as the factors associated with loss of correction in pediatric patients undergoing pedicle screw fixation for treatment of SCI-related scoliosis.

METHODS

All consecutive pediatric patients with spinal cord injury and paralytic scoliosis managed with pedicle screw constructs were identified at a single institution. Clinical and radiographic parameters were reviewed and analyzed with specific focus on parameters associated with loss of correction at an average follow-up of 2 years.

RESULTS

Approximately 15 % of patients had a loss of correction of greater than 10° of Cobb angle. Postoperative sagittal imbalance was found to be significantly greater in patients who lost greater than 10° of correction compared to patients who did not lose correction (53.6 ± 39.9 vs 4.3 ± 41.3 mm, p = 0.02).

CONCLUSIONS

Correction of patients with paralytic associated scoliosis should aim for a neutral sagittal balance in order to prevent postoperative loss of correction. Further study is needed on this subgroup of patients with scoliosis given the differences in strategies needed to correct and maintain their deformity correction.

Do anchor density or pedicle screw density correlate with short-term outcome measures in adolescent idiopathic scoliosis surgery?

STUDY DESIGN

Retrospective review.

OBJECTIVE

Determine if factors under surgeon control (anchor density or pedicle screw density) or those not under surgeon control (curve magnitude, levels requiring fusion, and curve flexibility) correlate with standard, short-term quality and outcome measures for adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Pedicle screw fixation has revolutionized posterior spinal instrumentation and fusion for adolescent idiopathic scoliosis and seems to provide greater radiographical coronal plane curve correction than less expensive constructs. Other clinically relevant improvements in outcome have been difficult to demonstrate.

METHODS

Retrospective review of 119 posterior spinal instrumentation and fusion cases for adolescent idiopathic scoliosis by 4 surgeons at 1 institution. Average follow-up was 586.7 days. Outcome measures were main thoracic curve correction, complications, reoperations, infection, intensive care unit days, length of stay, estimated blood loss, transfusion, procedure time, implant charges, and total hospital charges. "Surgeon-dependent" variables were implant density (fixation/instrumented level) and pedicle coefficient (implant density × percentage of anchors that are pedicle screws). "Surgeon-independent" variables were main thoracic curve magnitude, main thoracic curve flexibility, and levels fused. Correlations were estimated using Pearson correlation coefficients. One-way analysis of variance was used to estimate the effect of "type of surgeon" or "surgeon" on surgeon-dependent variables.

RESULTS

Complications, reoperations, and infections did not correlate with surgeon-dependent or surgeon-independent variables. Main thoracic curve correction correlated strongly with curve flexibility (correlation coefficient [cc] = 0.4089, P < 0.0001). Surgeon-independent variables were levels fused correlated significantly with procedure time (cc = 0.610, P < 0.001), hospital charges (cc = 0.309, P < 0.001), hospital length of stay (cc = 0.366 [P < 0.001]), implant charges (cc = 0.199, P < 0.047), and estimated blood loss (cc = 0.243, P < 0.013). Surgeon-dependent variables were implant density significantly correlated with implant charges (cc = 0.243, P < 0.015) and inversely with length of stay (cc = -0.236, P < 0.015). Pedicle coefficient was not significantly correlated with any outcome measure.

CONCLUSION

Levels fused, a surgeon-independent variable, had the most consistently strong correlations with standard short-term quality indicators. With physician grading by payers largely dependent on easily measured outcomes from medical records, hospital and billing records, physicians need to be aware of the surgeon-dependent and surgeon-independent variables that may affect their outcomes and cost-effectiveness profile.

LEVEL OF EVIDENCE

3.

Multicenter Comparison of the Factors Important in Restoring Thoracic Kyphosis During Posterior Instrumentation for Adolescent Idiopathic Scoliosis

STUDY DESIGN

Multicenter review, prospectively collected data.

OBJECTIVES

To determine factors predictive of postoperative correction of hypokyphosis when segmental posterior pedicle screw implants were used in treating thoracic adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Correcting hypokyphosis, which is common in patients with thoracic AIS, may be important in preventing junctional kyphosis, maintaining lumbar lordosis, and improving pulmonary function.

METHODS

A multicenter, prospective database was reviewed for Lenke type 1-4 AIS patients with preoperative kyphosis of 5° to 20°, treated with posterior pedicle screws and 5.5-mm rods. Surgeons with a minimum of 20 patients identified were included. Patients were divided into 2 groups postoperatively based on first erect X-rays: those remaining hypokyphotic (HK) (T5-T12 less than 20° or an increase less than 5° in T5-T12 kyphosis) and those restored to normal kyphosis (NK) (T5-T12 greater than 20° with 5° or more increase). Regression analysis was done on 5 preoperative factors thought to influence the postoperative kyphosis: preoperative kyphosis, surgeon, rod material (standard, high-strength, and ultra-high-strength steel; titanium; and cobalt chromium), implant density, and use or no use of a posterior release (Ponte osteotomies).

RESULTS

Of 280 patients included, 222 remained hypokyphotic and 53 achieved normal kyphosis. There were no differences in preoperative kyphosis (13.4° ± 5°, HK group vs. 14.5° ± 4°, NK group) and age (14.7, HK group vs. 14.6, NK group) between patients brought to greater than 20° (NK) and those who remained less than 20° (HK). Of the factors evaluated, the surgeon who performed the operation was the only significant predictor of restoration of normal kyphosis. Comparison of surgeons showed that the rate of normalizing kyphosis ranged from 6% to 42% (p = .001). There was no difference in the degree of preoperative kyphosis among surgeons.

CONCLUSIONS

Restoration of thoracic kyphosis remains a challenge in posteriorly treated thoracic AIS patients. The surgeon was the only significant predictor of restoring normal kyphosis, which emphasizes the importance of intraoperative techniques.