The impact of direct vertebral body derotation on the lumbar prominence in Lenke Type 5C curves

Comparison between the lowest instrumented vertebrae L3 with the use of direct vertebrae rotation (DVR) and the lowest instrumented vertebrae L4 for non-DVR in adolescents with idiopathic scoliosis Lenke 5C/6C: when LEV is L4

OBJECTIVE

As there are no substantial selection criteria for determining the lowest instrumented vertebra (LIV) in adolescent idiopathic scoliosis (AIS) Lenke 5C/6C, thus, many surgeons base their selection on experience. The study aims to compare the selection of the lowest instrumented vertebrae (LIV) lumbar vertebra three (L3) with the use of direct vertebrae rotation (DVR) to the lowest instrumented vertebrae (LIV) lumbar vertebra four (L4) with the use of non-DVR for the correction of adolescent idiopathic scoliosis (AIS) Lenke 5C/6C when the lower end vertebrae (LEV) is at lumbar vertebrae four (L4).

METHODS

This prospective study involved 101 patients who were divided into two groups based on different techniques. The patients were prospectively followed up for at least four years. All patients included in the study had a lower end vertebra (LEV) at L4, while patients older than 18 years and patients with prior surgical procedures were excluded. The DVR group consisted of 49 patients, and the non-DVR group included 51 patients.

RESULTS

The preoperative mean LIV disc angle was 3.1 ± 3 and 3.1 ± 1, P = 0.097, which corrected to 1.2 ± 0 and 1.1 ± 0 in both groups at 4-year follow-up without statistical significance. The LIVDA and LIVT were statistically insignificant at the preoperative, and there were no significant differences at the follow-up visitation. The DVR group achieved a satisfactory coronal and Cobb's angle correction compared to the NDVR group; however, there were no statistical differences at the follow-up visitations. Both groups achieve a satisfactory correction rate without substantial significance in clinical and radiological outcomes. Furthermore, no post-surgical complications were recorded in either group.

CONCLUSIONS

DVR is suitable for selecting L3 as the LIV in AIS Lenke 5C/6C compared to L4 in non-DVR. DVR preserved more segments without substantial complications during the follow-up visitations. Nevertheless, both groups will continue to be followed up to prevent adding-on post-surgical complications.

Rotational Assessment of Thoracolumbar/Lumbar Curves According to Lowest Instrumented Vertebra Level

Background

It is not clearly defined in the literature how the lowest instrumented vertebra (LIV) selection effects the rotation of lumbar vertebrae at fused and unfused levels in thoracolumbar/lumbar (TL/L) curves. The aim of this study was to evaluate the rotational profile of structural TL/L curves, corrected with rod derotation manoeuvre, according to LIV level.

Methods

82 consecutive AIS patients with structural TL/L curves who were treated with long segment posterior instrumentation and fusion were retrospectively evaluated. Patients were divided into three groups according to LIV level: lower end vertebra (LEV) group (32 patients), LEV-1 group (23 patients) and LEV + 1 group (27 patients). Cobb angles of structural curves, coronal and sagittal balance were evaluated with direct roentgenograms. Rotation of upper end vertebra, apical vertebra, LIV-1, LIV and LIV + 1 was evaluated with computerised tomography. Clinical outcomes were assessed using SRS-22 questionnaire.

Results

Mean follow-up time was 31 months (range 24-42 months). Preoperative LIV rotation was measured as 16.03°, 16.08° and 12.68° in LEV, LEV-1 and LEV + 1 groups, which changed postoperatively as 13.36°, 16.52° and 9.74° respectively. Postoperative LIV-1, LIV and LIV + 1 rotation values were significantly higher in LEV-1 group compared to LEV + 1 group. None of the patients developed coronal or sagittal imbalance. No significant differences were observed between the groups in terms of SRS-22 scores.

Conclusions

Axial rotation of LIV and vertebrae adjacent to LIV is higher when the fusion is stopped at LEV-1. However, higher rotation does not seem to cause poor radiologic and clinical outcomes in the last follow-up.

Midterm surgical outcomes of a short fusion strategy for adolescent idiopathic scoliosis with Lenke 5C curve

BACKGROUND CONTEXT

A previous study examined the short-term (2 years) outcomes of a short fusion strategy for Lenke type 5C curves. This strategy had a little less correction rate with no difference in coronal and sagittal balance and SRS-22 scores to those of a conventional strategy and was superior in operative time and intraoperative bleeding. However, its effectiveness in longer follow-up periods was unknown.

PURPOSE

To assess midterm surgical outcomes of a short fusion strategy for adolescent idiopathic scoliosis (AIS) with Lenke type 5C curve, involving posterior correction and fusion surgery (PSF) using pedicle-screw constructs.

STUDY DESIGN

Retrospective case series.

PATIENT SAMPLE

Twenty-nine patients who underwent PSF for AIS with Lenke type 5C curve with a minimum 5-year follow-up.

OUTCOME MEASURES

Radiographic parameters and SRS-22.

METHODS

We compared radiographic parameters and clinical outcomes between patients with an upper instrumented vertebra (UIV) at the end vertebra (EV) (n=12) and those treated by short fusion (S), with a UIV one level caudal to the EV (n=17).

RESULTS

A preoperative mean Cobb angle of 51.9±13.8° was corrected to 11.7±7.7° in the EV group, and an angle of 46.0±6.6° was corrected to 9.3±5.2° in the S group. The correction was maintained in both groups at the final follow-up, and the mean correction loss was 2.8±6.8° in the EV and 6.5±6.5° in the S group (p=.143). The mean correction rate at the final follow-up was not significantly different between the EV (71.4±11.8%) and S (64.9±13.7%) groups (p=.199). A Cobb angle of a thoracic curve was significantly improved immediately after surgery and maintained during the follow-up period in the both groups. Coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, L4 tilt, UIV/LIV tilt, shoulder balance, and SRS-22 had no difference between the two groups.

CONCLUSIONS

There was no difference in radiographic parameters and SRS-22 between patients treated with a UIV at the UEV and patients treated using a short fusion strategy, in which the UIV was one level caudal to the UEV. The short fusion strategy can be one of the alternatives in PSF for Lenke type 5C curves, at least in 5-year time frame.

Sagittal Alignment Profile Following Selective Thoracolumbar/Lumbar Fusion in Patients With Lenke Type 5C Adolescent Idiopathic Scoliosis

STUDY DESIGN

A retrospective case series.

OBJECTIVE

This study aimed to report the sagittal outcome measures in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS) undergoing thoracolumbar/lumbar (TL/L) fusion surgery.

SUMMARY OF BACKGROUND DATA

Previous studies have demonstrated coronal correction of Lenke type 5C AIS by selective TL/L fusion surgery. However, little is known about the sagittal influence of selective TL/L curve correction in Lenke type 5C AIS.

METHODS

Thirty-nine patients with Lenke type 5C AIS underwent selective posterior TL/L curves fusion (mean age, 15.9 ± 2.1 yrs). Preoperative and postoperative radiographic and clinical parameters were analyzed at a minimum 2-year follow-up period. Radiographic parameters were compared between patients with Lenke sagittal modifier normal (Group N) to those with Lenke sagittal modifier minus (Group M).

RESULTS

The main TL/L Cobb angle was 46.3° ± 7.7° preoperatively and 20.7° ± 5.3° (P < 0.0001) at 2-year follow-up. Also, thoracic kyphosis (TK) (T1-12) angle was 29.0° ± 11.3° preoperatively and 36.4° ± 10.3° at follow-up (P < 0.001), and TK (T5-12) angle was 18.1° ± 10.2° preoperatively and 25.9° ± 8.9° at follow-up (P < 0.001). The cervical lordosis (CL) was 9.6° ± 11.6° preoperatively and 6.1° ± 10.9° at follow-up (P = 0.037). Compared with the Lenke sagittal modifier groups, preoperative TK (T1-12), TK (T5-12), thoracolumbar kyphosis (TLK), and CL were significantly different from both the groups; and after the surgery, no significant differences in these parameters were observed between the two groups.

CONCLUSION

After the selective TL/L posterior fusion surgery in patients with Lenke type 5C AIS, the sagittal alignment profile, including TK, TLK, C7 sagittal vertical axis, T1 slope, and CL, was significantly changed. With regard to the sagittal aspect, selective TL/L surgery was more likely to affect Group M than Group N.

LEVEL OF EVIDENCE

4.

Differential Rod Contouring is Essential for Improving Vertebral Rotation in Patients With Adolescent Idiopathic Scoliosis: Thoracic Curves Assessed With Intraoperative CT

STUDY DESIGN

A case series.

OBJECTIVE

We investigated the contributions of rod contouring and differential rod contouring (DRC) to the reduction of apical axial vertebral body rotation in patients with adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

DRC is used for posterior spinal correction and fusion. The contribution of DRC to vertebral body derotation is unclear.

METHODS

We analyzed the results of intraoperative computed tomography (CT) in 40 consecutive AIS patients with thoracic curves (Lenke type I or II, 35; type III or IV, 5). Rod contour before initial rod rotation was analyzed by x-ray. Periapical rod contour between concave and convex rod rotation (RR) were analyzed by cone-beam CT imaging. To analyze the reduction of vertebral body rotation with DRC, intraoperative cone-beam CT scans of the three apical vertebrae of the major curve of the scoliosis (120 vertebrae) were taken post-concave RR and post-convex DRC in all patients. The angle of vertebral body rotation was measured. In addition, the contribution of rod contouring to apical vertebral body derotation was analyzed. Rib hump indices (RHi) were measured by pre- and postoperative CT.

RESULTS

The mean vertebral body rotation angles post-concave RR and post-convex DRC were 15.3° and 9.3°, respectively, for a mean reduction of vertebral rotation in convex DRC after concave RR of 6.0° for thoracic curves (P < 0.001). The RHi was significantly improved by DRC (P < 0.05). Improved apical vertebral rotation was significantly correlated with the difference of apical rod curvature between concave and convex. Vertebral derotation was significantly higher in curves with > 10° difference between concave and convex rod curvature than differences < 10°.

CONCLUSION

DRC contributed substantially to axial derotation and reducing rib hump in thoracic scoliosis. The degree of apical rod curvature correlated with the degree of apical vertebral derotation.

LEVEL OF EVIDENCE

4.

A biomechanical investigation of different screw head designs for vertebral derotation in scoliosis surgery

BACKGROUND CONTEXT

The posterior pedicle screw-rod system, which is widely used to correct spinal deformities, achieves a good correction rate in the frontal and coronal planes but not in the axial plane. Direct vertebral derotation (DVD) was developed to correct axial plane deformities. However, the design of screw head and body connection, in terms of monoaxial, polyaxial, and uniplanar screw, may influence the efficiency of DVD.

PURPOSE

This study compared the efficiency of a newly designed uniplanar screw with that of monoaxial and polyaxial screws in the DVD maneuver.

STUDY DESIGN

A porcine spine model and monoaxial, polyaxial, and uniplanar screws were used to examine the biomechanics of the DVD maneuver.

METHODS

Six T7-T13 porcine thoracic spine segments were used as test specimens in this study. Pedicle screws were inserted in the left pedicles of the T9-T11 spinal segments and then connected with a rod. Three types of pedicle screws with different screw head designs (monoaxial, polyaxial, and uniplanar) were employed in this study. The material testing system (MTS) machine generated a rotational moment through the derotational tube on the T10 (apical body) pedicle screw, which simulated the motion applied during the surgical vertebral derotational procedure. The pedicle strain and the kinematics of the vertebral body and derotational tube were recorded to evaluate the derotational efficiency of different pedicle screw head designs.

RESULTS

The variances of the derotation for the monoaxial, polyaxial, and uniplanar screws were 2.22°±1.43°, 32.23°±2.26°, and 4.75°±1.60°, respectively; the derotation efficiency was 0.65, 0.51, and 0.12, respectively, when the torques of the spinal constructs reached 3 Nm. The rotational variance of the polyaxial screw was statistically greater than that of the monoaxial and uniplanar screws (p<.05). The maximum micro-strains of the pedicles for the monoaxial, polyaxial, and uniplanar screws were 1,067.45±550.35, 747.68±393.56, and 663.55±271.04, respectively, with no statistically significant differences (p>.05).

CONCLUSIONS

The screw head design played an important role in the efficiency and variance of the derotation during the DVD maneuver. The derotational efficiency of the newly designed uniplanar screw was closer to that of the monoaxial screw group than to that of the polyaxial screw group. The polyaxial screw was inferior to DVD owing to a derotational variance between the derotational tube and the apical body that was correlated with the range of motion of the screw head. In the present study, the pedicle strain was similar in all groups. However, the pedicle strain of the uniplanar screw group was lower than that of the monoaxial screw group and was similar to that of the polyaxial screw group when the angle of rotation of the apical body increased.

The effect of different screw-rod design on the anti-rotational torque: a biomechanical comparison of three conventional screw-rod constructs

Background

Screw-rod constructs have been widely used to correct spinal deformities, but the effects of different screw-rod systems on anti-rotational torque have not been determined. This study aimed to analyze the biomechanical effect of different rod-screw constructs on anti-rotational torque.

Methods

Three conventional spinal screw-rod systems (Legacy, RF-F-10 and USSII) were used to test the anti-rotational torque in the material test machine. ANOVA was performed to evaluate the anti-rotational capacity of different pedicle screws-rod constructs.

Results

The anti-rotational torque of Legacy group, RF-F-10 group and USSII group were 12.3 ± 1.9 Nm, 6.8 ± 0.4 Nm, and 3.9 ± 0.8 Nm, with a P value lower than 0.05. This results indicated that the Legacy screws-rod construct could provide a highest anti-rotation capacity, which is 68% and 210% greater than RF-F-10 screw-rod construct and USSII screw-rod respectively.

Conclusions

The anti-rotational torque may be mainly affected by screw cap and groove design. Our result showed the anti-rotational torque are: Legacy system > RF-F-10 system > USSII system, suggesting that appropriate rod-screw constructs selection in surgery may be vital for anti-rotational torque improvement and preventing derotation correction loss.

Correction manoeuvres in the surgical treatment of spinal deformities

Correction manoeuvres are as important as the other issues such as hardware selection, graft options, fusion and osteotomy techniques in the surgical treatment of spinal deformities.The property of materials demonstrating both viscous and elastic characteristics when undergoing deformation is called visco-elasticity. Purely elastic materials change in shape with a stress, and go back to their initial form when the stress is removed. However, visco-elastic materials, like the spine, may protect their new formation unless a back stress is applied. Time is a very important parameter during manoeuvre application to the spine because of its visco-elastic behavior.The most common correction manoeuvres that can be used for spinal deformities are rod de-rotation, distraction-compression, in situ rod bending, segmental de-rotation, en bloc de-rotation and cantilever.Spontaneous correction of a minor curve is possible after selective fusion of a major curve due to coupling phenomenon. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.170002. Originally published online at www.efortopenreviews.org.

Surgical treatment of Lenke 5 adolescent idiopathic scoliosis: Comparison of anterior vs posterior approach

AIM

To compare the posterior vs anterior approaches for fusion of Lenke 5 adolescent idiopathic scoliosis curves, matched for curve magnitude and for the distal level of fixation (dLOF) standardized to the third lumbar vertebrae (L3).

METHODS

A prospectively collected multicenter database was used for this retrospective comparative study. Our dependent variables included sagittal and coronal radiographic measurements, number of fused vertebrae, estimated blood loss, length of hospitalization and SRS total and individual domain scores at the two-year follow-up. Subject demographics were similar for all group comparisons. Independent t-test was used to compare groups for all analyses at P < 0.01.

RESULTS

For all matched cases of Lenke 5 curves, a selective approach was used only 50% of the time in cases undergoing a posterior fusion. When comparing a posterior selective approach to an anterior selective approach, surgeons utilizing a posterior approach fused significantly more levels than surgeons using an anterior approach with no other significant differences in radiographic or SRS outcomes (Ant = 4.8 ± 1.0 levels vs post = 6.1 ± 1.0 levels, P < 0.0001). When the dLOF was standardized to L3, the anterior approached provided significantly greater lumbar Cobb percent correction than the posterior approach (Ant = 69.1% ± 12.6% vs post = 54.6% ± 16.4%, P = 0.004), with no other significant radiographic or SRS score differences between approaches.

CONCLUSION

Surgeons treating Lenke 5c curves with a posterior instrumentation and fusion vs an anterior approach include more motion segments, even with a selective fusion. When controlled for the distal level of fixation, the anterior approach provides greater correction of the thoracolumbar curve.

Rod rotation and differential rod contouring followed by direct vertebral rotation for treatment of adolescent idiopathic scoliosis: effect on thoracic and thoracolumbar or lumbar curves assessed with intraoperative computed tomography

BACKGROUND CONTEXT

Although direct vertebral rotation (DVR) is now used worldwide for the surgical treatment of adolescent idiopathic scoliosis (AIS), the benefit of DVR in reducing vertebral body rotation in these patients has not been determined.

PURPOSE

We investigated a possible additive effect of DVR on further reduction of vertebral body rotation in the axial plane following intraoperative rod rotation or differential rod contouring in patients undergoing surgical treatment for AIS.

STUDY DESIGN/SETTING

The study was a prospective computed tomography (CT) image analysis.

PATIENT SAMPLE

We analyzed the results of the two intraoperative procedures in 30 consecutive patients undergoing surgery for AIS (Lenke type I or II: 15; Lenke type V: 15).

OUTCOME MEASURES

The angle of reduction of vertebral body rotation taken by intraoperative CT scan was measured and analyzed. Pre- and postoperative responses to the Scoliosis Research Society 22 Questionnaire (SRS-22) were also analyzed.

METHODS

To analyze the reduction of vertebral body rotation with rod rotation or DVR, intraoperative cone-beam CT scans of the three apical vertebrae of the major curve of the scoliosis (90 vertebrae) were taken pre-rod rotation (baseline), post-rod rotation with differential rod contouring, and post-DVR in all patients. The angle of vertebral body rotation in these apical vertebrae was measured and analyzed for statistical significance. Additionally, differences between thoracic curve scoliosis (Lenke type I or II; 45 vertebrae) and thoracolumbar or lumbar curve scoliosis (Lenke type V; 45 vertebrae) were analyzed. Pre- and postoperative SRS-22 scores were evaluated in all patients.

RESULTS

The mean (90 vertebrae) vertebral body rotation angles at baseline, post-rod rotation or differential rod contouring, and post-rod rotation or differential rod contouring or post-DVR were 17.3°, 11.1°, and 6.9°, respectively. The mean reduction in vertebral body rotation with the rod rotation technique was 6.8° for thoracic curves and 5.7° for thoracolumbar or lumbar curves (p<.00005). The mean additional reduction in rotation with the DVR technique was 3.4° for thoracic curves and 4.9° for thoracolumbar or lumbar curves (p<.00005). Direct vertebral rotation displayed a slightly but significantly greater additive effect in reducing rotation following initial reduction with rod rotation or differential rod contouring in thoracolumbar or lumbar than in thoracic curves. In the SRS-22 results, postoperative self-image was significantly better than preoperative image in both groups.

CONCLUSIONS

Direct vertebral rotation contributed an additional reduction in vertebral body rotation in thoracic and thoracolumbar or lumbar curves. The DVR technique is likely to be more useful in thoracolumbar or lumbar curve scoliosis than in thoracic curve scoliosis.

Posterior correction and fusion surgery using pedicle-screw constructs for Lenke type 5C adolescent idiopathic scoliosis: a preliminary report

STUDY DESIGN

A retrospective case series.

OBJECTIVE

To assess whether a short fusion strategy is applicable when treating adolescent idiopathic scoliosis with Lenke type 5C curve by posterior correction and fusion surgery using pedicle-screw constructs.

SUMMARY OF BACKGROUND DATA

Previous studies have discussed the selection of the lower instrumented vertebra to best preserve motion segments and obtain coronal balance. However, reports evaluating the selection of the upper instrumented vertebra when treating Lenke type 5C curves are not available.

METHODS

We evaluated 29 patients who were treated surgically for adolescent idiopathic scoliosis with Lenke type 5C curve (mean age, 16.8 ± 4.7 yr; range, 10-29 yr). The mean follow-up period was 28.0 ± 6.3 months (range, 24-48 mo). We compared radiographical parameters and clinical outcomes between patients with an upper instrumented vertebra at the end vertebra (EV) (n = 10) and those treated by short fusion (S group), with a upper instrumented vertebra 1-level caudal to the EV (n = 19 patients).

RESULTS

In the EV group, a preoperative mean Cobb angle of 50°± 15° was corrected to 8°± 7°, which was maintained at the final follow-up (7°± 1°). In the S group, a mean preoperative Cobb angle of 47°± 4° was corrected to 8°± 5°, but this increased significantly to 12°± 7° at final follow-up (P = 0.033). The mean correction rate at final follow-up was significantly lower in the S group (72%) than in the EV group (86%) (P = 0.027). Coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, L4 tilt, and clinical outcomes evaluated by Scoliosis Research Society patient questionnaire-22 were equivalent between the 2 groups.

CONCLUSION

Scoliosis Research Society patient questionnaire-22 scores and radiographical parameters other than the correction rate were equivalent between the 2 groups. A short fusion strategy, in which the upper instrumented vertebra is 1-level caudal to the upper EV, is applicable to posterior correction and fusion surgery with pedicle-screw constructs for Lenke type 5C curves.

Radiographic, clinical, and patients' assessment of segmental direct vertebral body derotation versus simple rod derotation in main thoracic adolescent idiopathic scoliosis: a prospective, comparative cohort study

PURPOSE

The application of vertebral body derotation (DVBD) is still controversial by now; the purpose of this prospective cohort study was to compare comprehensive outcomes between segmental DVBD and simple rod derotation (SRD) especially in main thoracic adolescent idiopathic scoliosis.

METHODS

36 patients in DVBD group and 45 patients in SRD group were with a 2-year follow-up. Among them, 19 DVBD patients and 16 SRD patients received CT scan examinations.

RESULTS

There were no significant difference between the groups in preoperative main thoracic Cobb, apical vertebral rotation and rib hump. Apical vertebral rotation measured from CT scans was 9.7° ± 2.0° versus 15.3° ± 2.4° (p < 0.001) postoperatively in the DVBD and SRD patients, respectively. At 2-year follow-up, the main thoracic Cobb was 14.2° ± 1.6° versus 14.7° ± 1.7° (p = 0.18), rib hump was 6.4° ± 3.8° versus 6.8° ± 3.1° (p = 0.60) in DVBD group and SRD group. Patients' assessments of both groups were improved in Spinal Appearance Questionnaire (SAQ) and Scoliosis Research Society-22 Questionnaire (SRS-22), but showed no significant difference at follow-up (p = 0.47 and 0.60).

CONCLUSION

Although segmental DVBD showed excellent radiographic correction of axial spinal deformity postoperatively, there was no more correction of clinical rib hump or better patients' assessment than SRD at follow-up in our data.

Quantification of the spatial strain distribution of scoliosis using a thin-plate spline method

The objective of this study was to quantify the three-dimensional spatial strain distribution of a scoliotic spine by nonhomogeneous transformation without using a statistically averaged reference spine. The shape of the scoliotic spine was determined from computed tomography images from a female patient with adolescent idiopathic scoliosis. The shape of the scoliotic spine was enclosed in a rectangular grid, and symmetrized using a thin-plate spline method according to the node positions of the grid. The node positions of the grid were determined by numerical optimization to satisfy symmetry. The obtained symmetric spinal shape was enclosed within a new rectangular grid and distorted back to the original scoliotic shape using a thin-plate spline method. The distorted grid was compared to the rectangular grid that surrounded the symmetrical spine. Cobb's angle was reduced from 35° in the scoliotic spine to 7° in the symmetrized spine, and the scoliotic shape was almost fully symmetrized. The scoliotic spine showed a complex Green-Lagrange strain distribution in three dimensions. The vertical and transverse compressive/tensile strains in the frontal plane were consistent with the major scoliotic deformation. The compressive, tensile and shear strains on the convex side of the apical vertebra were opposite to those on the concave side. These results indicate that the proposed method can be used to quantify the three-dimensional spatial strain distribution of a scoliotic spine, and may be useful in quantifying the deformity of scoliosis.

En bloc vertebral column derotation provides spinal derotation but no additional effect on thoracic rib hump correction as compared with no derotation in adolescents undergoing surgery for idiopathic scoliosis with total pedicle screw instrumentation

STUDY DESIGN

A comparative review of 2 cohorts with prospective data collection.

OBJECTIVE

To compare clinical and radiographical parameters in patients with adolescent idiopathic scoliosis undergoing surgery, using total pedicle screw instrumentation with and without en bloc vertebral column derotation (DVR).

SUMMARY OF BACKGROUND DATA

All pedicle screw instrumentations with or without DVR are an effective surgical method for adolescent idiopathic scoliosis correction. However, there are limited data comparing pedicle screw instrumentation alone with pedicle screws with DVR on clinical and radiographical outcomes.

METHODS

We followed 72 consecutive children and adolescents (14 males, mean age at surgery: 14.7 [range, 9.0-18.0] years; 6 juveniles, 66 adolescents) operated for a structural thoracic idiopathic scoliosis (Lenke 1-4, or 6) using all pedicle screw construct in a prospective manner for a minimum of 2 years. Of them, 24 had pedicle screw instrumentation with apical monoaxial screws without derotation (N-DVR) and 48 with en bloc DVR.

RESULTS

Preoperatively, the mean (SD) main thoracic curve was 56° ± 9° and 57° ± 11° and was corrected to 16° ± 6° in both groups at 2-year follow-up (not significant). Thoracic rib hump averaged 12.3° ± 3.6° versus 14.2° ± 5.0° (P = 0.075) preoperatively and 7.2° ± 3.8° versus 8.3° ± 3.7° at 2-year follow-up in the N-DVR and in the DVR both groups, respectively (P = 0.30). Correction of spinal rotation in the main thoracic curve as assessed by the Upsani score was significantly better in the DVR group than in the N-DVR group at 6 months (P = 0.038) and 2-year follow-up (P = 0.039). Thoracic kyphosis reduced from a mean of 23° ± 18° to 20° ± 9° in the N-DVR group but remained unchanged in the DVR group (P = 0.11 between groups at 2-year follow-up).

CONCLUSION

En bloc DVR has a significant effect on radiographical spinal column derotation and may help prevent flattening of thoracic kyphosis, but this derotation is not reflected by better thoracic rib hump correction at 2-year follow-up.

LEVEL OF EVIDENCE

2.

Coronal realignment and reduction techniques and complication avoidance

Scoliosis is a broad term encompassing multiple pathologies with different etiologies. Patients may range from the infant with congenital deformity, to the adolescent with idiopathic scoliosis, to the elderly patient with severe degenerative scoliosis. Treatment must be tailored to individual circumstances and the pathoanatomy of each deformity. Various coronal reduction techniques have been described and will be discussed within this article. While scoliosis is generally considered a deformity in the coronal plane, often deformity is present in the sagittal and axial planes also. Treatment of these deformities can require osteotomies or vertebral column resections, techniques further discussed in accompanying articles.