Three-dimensional Deformity Correction Research Articles

Three-dimensional deformity correction in adolescent idiopathic scoliosis patients: what are the benefits of hybrid apical sublaminar bands versus all-pedicle screws?

The amount of three-dimensional (3D) correction with apical sublaminar band (hybrid-SLB) technique has not been compared to all-pedicle screw instrumentation for adolescent idiopathic scoliosis (AIS) using detailed axial correction metrics or comparable rod types. Our purpose is to compare 3D improvement in AIS deformities following posterior spinal instrumentation and fusion (PSIF) with hybrid-SLB and segmental correction to all-pedicle screw correction. Patients ages 10-18 years with AIS who underwent PSIF between 2015 and 2022 and had preoperative and postoperative EOS imaging were included. Electronic medical records were reviewed for demographic, Lenke classification, operative technique, and 3D EOS data. Average changes in major and minor Cobb angle, axial rotation, thoracic kyphosis, and lumbar lordosis were compared. Ninety-five patients met inclusion criteria with 55 in the hybrid-SLB group (mean age 14.9 ± 1.9 years) and 40 in all-pedicle screw (mean age 14.7 ± 2.1 years). While all-pedicle screw demonstrated greater correction of major (45.7 ± 13.4 vs 37.9 ± 14.3 degrees; P = 0.008) and minor (28.7 ± 13.1 vs 17.8 ± 12.5 degrees; P = 0.001) Cobb angles, hybrid-SLB showed greater increase in T4-T12 kyphosis (13.3 ± 15.3 vs 5.6 ± 13.5 degrees; P = 0.01). Correction of T1-T12 kyphosis, axial rotation, and lumbar lordosis was similar between groups. 3D EOS analysis of AIS patients before and after PSIF revealed that all-pedicle screw constructs had greater overall coronal plane correction and hybrid-SLB had greater thoracic sagittal plane correction. Axial corrective abilities were similar. Hybrid-SLB may have advantages for correction of thoracic lordosis or hypokyphosis. Level of evidence: Level III, retrospective cohort study.

Anterior vertebral body tethering for idiopathic scoliosis in growing children: A systematic review.

BACKGROUNDThe management of idiopathic scoliosis (IS) in skeletally immature patients should aim at three-dimensional deformity correction, without compromising spinal and chest growth. In 2019, the US Food and Drug Administration approved the first instrumentation system for anterior vertebral body tethering (AVBT), under a Humanitarian Device Exception, for skeletally immature patients with curves having a Cobb angle between 35° and 65°.AIMTo summarize current evidence about the efficacy and safety of AVBT in the management of IS in skeletally immature patients.METHODSFrom January 2014 to January 2021, Ovid Medline, Embase, Cochrane Library, Scopus, Web of Science, Google Scholar and PubMed were searched to identify relevant studies. The methodological quality of the studies was evaluated and relevant data were extracted.RESULTSSeven clinical trials recruiting 163 patients were included in the present review. Five studies out of seven were classified as high quality, whereas the remaining two studies were classified as moderate quality. A total of 151 of 163 AVBT procedures were performed in the thoracic spine, and the remaining 12 tethering in the lumbar spine. Only 117 of 163 (71.8%) patients had a nonprogressive curve at skeletal maturity. Twenty-three of 163 (14.11%) patients required unplanned revision surgery within the follow-up period. Conversion to posterior spinal fusion (PSF) was performed in 18 of 163 (11%) patients.CONCLUSIONAVBT is a promising growth-friendly technique for treatment of IS in growing patients. However, it has moderate success and perioperative complications, revision and conversion to PSF.

Does Implant Density Impact Three-Dimensional Deformity Correction in Adolescent Idiopathic Scoliosis with Lenke 1 and 2 Curves Treated by Posterior Spinal Fusion without Ponte Osteotomies?

Study DesignRetrospective cohort study.PurposeTo determine whether implant density impact three-dimensional deformity correction in posterior spinal fusion (PSF) without Ponte osteotomies (POs) for patients with Lenke 1 and 2 adolescent idiopathic scoliosis (AIS).Overview of LiteratureCurrently, the optimal pedicle screw (PS) density for flexible moderate-sized thoracic AIS curve correction is still controversial. There are limited data regarding the impact of implant density on three-dimensional correction in PSF without the use of PO for thoracic AIS surgery.MethodsA database of patients with AIS with Lenke 1 and 2 curves treated with PSF without PO and instrumented with PSs and ≥2-year follow-up was reviewed. The preoperative, immediate, and final follow-up postoperative radiographs were analyzed. The correlation between PS density and the following factors were determined: major curve correction (MCC), correction index (CI; MCC/curve flexibility), kyphosis angle change, and rib index (RI) correction. Then, patients were divided into low-density (LD) and high-density (HD) groups according to mean PS density for the entire cohort (1.5 PS per level). Demographics and radiographic and clinical outcomes were compared between groups.ResultsThe study included 99 patients with Lenke 1 and 23 patients with Lenke 2 AIS. The average MCC was 67.2%. There was no correlation between screw density and these parameters: MCC (r=0.10, p=0.26), CI (r=0.16, p=0.07), change in T2–T12 kyphosis angle (r=−0.13, p=0.14), and RI correction (r=−0.09, p=0.37). Demographic and preoperative radiographic parameters were similar between the LD and HD groups. At the latest follow-up, there were no differences between the two groups in regard to MCC, CI, change in T2–T12 kyphosis angle, RI correction, and Scoliosis Research Society-30 scores (all p>0.05).ConclusionsThis study revealed no significant correlation between screw density and curve correction in any planes. HD construct may not provide better deformity correction in patients with flexible and moderate thoracic AIS undergoing PSF without PO.

A posterior-only approach for treatment of severe adolescent idiopathic scoliosis with pedicle screw fixation: A case series

IntroductionAdolescent idiopathic scoliosis (AIS) can lead to severe deformity. However, early detection and treatment can prevent its progression. Surgical instrumentation for scoliosis treatment has evolved from Harrington instrumentation to pedicle screws. However, there are still some concerns about the efficacy and long-term effects of pedicle screw fixation, and the clinical and radiographic outcomes of surgical treatment for severe AIS (>90°) by posterior spinal fusion alone need to be established. Presentation of caseEight patients with severe and rigid idiopathic scoliosis were recruited for this study. All surgeries were performed by one senior spine surgeon between 2015 and 2018. Free hand technique, intraoperative neurophysiologic monitoring (IONM), and intraoperative fluoroscopy to assess the screw position was performed. DiscussionSevere scoliosis results in a complex three-dimensional spinal deformity that often requires correction in multiple planes. Mean major coronal correction rate was 67% (45–80%). No major complications occurred during the perioperative period and after one year follow up. ConclusionPedicle screws provide three-dimensional deformity correction. There were no complications other than the low-grade late implant-associated infections. Posterior spinal fusion with pedicle screw-only instrumentation obtains a good and stable correction for severe scoliosis.

Posterior Correction Techniques for Adolescent Idiopathic Scoliosis.

Adolescent idiopathic scoliosis represents a complex, three-dimensional deformity of the spine. Posterior spinal fusion is commonly performed in severe cases to avoid the long-term adverse sequelae associated with progressive spinal deformity. The goals of spinal fusion include halting the progression of deformity, optimizing spinal balance, and minimizing complications. Recent advances in short-segment spinal fixation have allowed for improved three-dimensional deformity correction. Preoperative planning and assessment of spinal flexibility is essential for successful deformity correction and optimization of long-term outcomes. Judicious use of releases and/or spinal osteotomies may allow for increased mobility of the spine but are associated with increased surgical time, blood loss, and risk of complications. Appreciation of implant design and material properties is critical for safe application of correction techniques. Although multiple reduction techniques have been described, no single technique is optimal for every patient.

Unusual Complication After Genioplasty

Facial beauty depends on shape, proportion, and harmony between the facial thirds. The chin is one of the most important components of the inferior third and has an important role on the definition of facial aesthetic and harmony in both frontal and lateral views. There are 2 principal therapeutic approaches that one can choose to treat mental deformities, alloplastic implants, and mental basilar ostectomy, also known as genioplasty. The latest is more commonly used because of great versatility in the correction of three-dimensional deformities of the chin and smaller taxes of postoperative complications. Possible transoperative and postoperative complications of genioplasty include mental nerve lesion, bleeding, damage to tooth roots, bone resorption of the mobilized segment, mandibular fracture, ptosis of the lower lip, and failure to stabilize the ostectomized segment. The study presents 2 cases of displacement of the osteotomized segment after genioplasty associated with facial trauma during postoperative orthognathic surgery followed by rare complications with no reports in the literature.

Distraction osteogenesis for correction of three-dimensional deformities with shortening of lower limbs by Taylor Spatial Frame

Surgical results of correction of three-dimensional deformities with shortening of lower limbs by simple two-ring system of Taylor Spatial Frame have been reported. The deformities were caused by various kinds of skeletal disorders. Ten cases were successfully corrected using distraction osteogenesis, being one case showed recurrence of deformity due to the nature of the disease. The ranges of corrected deformities were 5 degrees-55 degrees in coronal angulation, 2 degrees-47 degrees in sagittal angulation, and 5 degrees-40 degrees in rotational deformities. Amount of lengthening ranged from 1.2 to 6.0 cm. Pin-site infection occurred in five cases, being no other complications. External fixation index was longer in a group of rotational correction over 10 degrees. The current report seems the first series of cases with four-dimensional deformities treated by distraction osteogenesis by TSF and may help to determine the indication of use of TSF in case of treatment of patients suffering from deformities in the lower limbs.

SURGICAL TREATMENT OF III–IV GRADE SCOLIOSIS WITH PLATE ENDOCORRECTOR

Objectives. To analyze the efficacy of surgery using the original plate endocorrectors for III–IV grade idiopathic progressing scoliosis. Materials and methods. Two-plate endocorrector was used in surgical treatment of 380 patients. Out of them 171 patients at the age of 13–15 years had vertebral body apophysis ossification of stage 2–3 according to Risser’s test. Scoliosis was congenital in 12 patients (3.2 %) and idiopathic in 368 patients (96.8 %). The smallest coronal angle of curve according to Cobb was 40°, the largest one – 145°. Surgery of severe IV grade scoliotic deformity (curve angle of 60–90°) was performed in 178 patients. Results. Patients with non-removable instrumentation show the maintenance of post-surgical correction within 75–80% in long-term follow-up period (up to 9 years). Complications related to the plate endocorrector were observed in 9.8 % of cases: aseptic serous reaction induced by instability of the construct elements – in 3.7 %, plate breakage and release of endocorrector locking – in 5.3 %. Conclusion. Plate endocorrector of the third generation provides effective three-dimensional deformity correction for idiopathic III–IV grade scoliosis. The endocorrector does not prevent further spine growth in children after surgery.

Vertebral Rotation and Thoracic Torsion in Adolescent Idiopathic Scoliosis

As a result of the increased appreciation of the three-dimensional nature of scoliosis and modern spinal instrumentation's improved corrective capabilities, there has been renewed interest in the correction and measurement of vertebral rotation. Computed tomography (CT), the gold standard for accuracy, is limited in its clinical utility owing to cost, radiation exposure, and the effects of postural changes on scoliosis curves and vertebral rotation. Consequently, the Perdriolle and Nash-Moe techniques remain the standard measurements for providing a reasonable estimate of pre- and postoperative vertebral rotation because of their simplicity. However, these techniques have considerable interobserver variability, and pedicle screw instrumentation obscures the landmarks necessary for utilizing these techniques for postoperative vertebral rotation assessment. The purpose of the present study was to assess the utility of alternate radiographic measures to assess vertebral rotation and thoracic torsion when compared with conventional measures on pre- and postoperative radiographs and CT evaluation. We reviewed the preoperative, immediate postoperative, and final follow-up radiographs, as well as the pre- and postoperative CT scans, of 19 patients (average age 15 years, 6 months) with Lenke 1 curves (average 55 degrees , range 47-66 degrees ), all treated with anterior spinal fusion. Coronal and sagittal Cobb angles as well as vertebral rotation (Perdriolle and Nash-Moe) at the superior uninstrumented, superior instrumented, apical, inferior instrumented, and inferior uninstrumented vertebrae were measured on all films, and vertebral rotation was assessed on the CT scans by a previously described method. Additionally, several measures of thoracic torsion (as a proxy for vertebral rotation and overall deformity improvement) were assessed. These included the rib-vertebral angle difference (RVAD), apical rib hump prominence (RH), apical vertebral body-rib ratio (AVB-R), and apical rib spread difference (ARSD). The postoperative main thoracic curve averaged 26 degrees (range 16-39 degrees , 52% correction) and 29 degrees (range 22-40 degrees , 47% correction) at final follow-up. For apical derotation, the postoperative CT improved from -11.5 degrees to -6.6 degrees and correlated significantly with the Cobb main thoracic curves (42% correction, r = 0.48, P = 0.003). There was weakly positive, but statistically significant, correlation between the pre- and postoperative CT scans and the corresponding Perdriolle and Nash-Moe measures of segmental rotation (r = 0.32-0.40, all P < 0.0001). The RVAD demonstrated poor correlation with the main thoracic curve values and correction, Perdriolle rotation and correction, and CT rotation and correction (r = -0.22-0.37, all P > 0.20). The apical RH demonstrated good correlation with the main thoracic curve (r = 0.65, P < 0.0001), apical Perdriolle rotation (r = 0.57, P < 0.0001), and CT apical rotation (r = 0.53, P = 0.002). We also found moderate correlation between the AVB-R and the main thoracic Cobb, apical Perdriolle, and CT (r = 0.57, 0.59, and 0.49, respectively; all P < 0.005). Similar relationships were found with the ARSD (r = 0.51, 0.47, and 0.43, respectively; all P < 0.02). The RH, AVB-R, and the ARSD-measures of thoracic torsion-demonstrated moderate to good overall correlation with the main thoracic curve Cobb angles, apical Perdriolle rotation, and apical CT rotation. These should be useful as clinical measures for assessing three-dimensional deformity correction on plane radiographs, especially for the intraoperative evaluation of vertebral derotation and thoracic symmetry restoration.

Direct vertebral rotation: a new technique of three-dimensional deformity correction with segmental pedicle screw fixation in adolescent idiopathic scoliosis.

A prospective study. To introduce a new technique, direct vertebral rotation, and to compare the surgical results of direct vertebral rotation with those of simple rod derotation. Pedicle screw fixation with a simple rod derotation maneuver enables a powerful coronal and sagittal plane correction in scoliosis surgery. However, the ability of achieving rotational correction is still unclear. Thirty-eight adolescent idiopathic scoliosis patients treated with segmental pedicle screw fixation were analyzed. The first group (n = 17) was treated by direct vertebral rotation; the second group (n = 21) was treated by simple rod derotation. All patients had a minimum follow-up of 2 years. Having similar preoperative curve patterns, both groups were evaluated for the deformity correction, lower instrumented vertebral tilt, and spinal balance. Apical vertebral rotation was evaluated by computed tomography scans. Surgical techniques of direct vertebral rotation were as follows: a precontoured rod was inserted into segmental screws on the concave side in thoracic scoliosis; a simple rod derotation was performed; and then the screws on the juxta-apical vertebrae, both on concave and convex sides, were rotated opposite direction to the rod derotation. Then, all the screws were sequentially tightened. In the direct vertebral rotation group, the average preoperative apical vertebral rotation of 16.7 degrees was corrected to 9.6 degrees, showing 42.5% correction, whereas in the simple rod derotation group, the correction was negligible from 16.1 degrees to 15.7 degrees (2.4%). In the direct vertebral rotation group, the average preoperative thoracic curve of 55 degrees was corrected to 12 degrees (79.6%), and the lumbar curve of 39 degrees was corrected to 7 degrees (80.5%). In the simple rod derotation group, the preoperative thoracic curve of 53 degrees was corrected to 17 degrees (68.9%), and the lumbar curve of 39 degrees was corrected to 16 degrees (62.2%). The average lower instrumented vertebral tilt correction was 80.6% and 66.3% in the directvertebral rotation and the simple rod derotation group, respectively. There were statistically significant differences in the coronal curve, lower instrumented vertebral tilt, and rotational correction (P < 0.05, Mann-Whitney U test). Thoracic kyphosis was improved in both groups. Segmental pedicle screw fixation with "direct vertebral rotation" showed better rotational and coronal correction than "simple rod derotation."

Determination of distal fusion level with segmental pedicle screw fixation in single thoracic idiopathic scoliosis.

A retrospective study was conducted. To determine the exact distal fusion level in the treatment of single thoracic idiopathic scoliosis (King Types 3 and 4) with segmental pedicle screw fixation. Pedicle screw fixation effectively shortens the distal fusion extent by improved three-dimensional deformity correction. However, the selection of distal fusion extent remains controversial in single thoracic idiopathic scoliosis. This study analyzed 42 patients with single thoracic adolescent idiopathic scoliosis (32 King 3 patients and 10 King 4 patients) who underwent segmental pedicle screw fixation and had a minimum follow-up period of 2 years (range, 2-6 years). The patients were grouped according to the distal fusion level with reference to the standing neutral rotated vertebra (NV) for comparison of deformity correction and spinal balance using standing radiographs. Failure to restore an adequate trunk balance and progression or extension of the primary curve (adding on) was considered unsatisfactory. Preoperative 50 degrees +/- 11 degrees of thoracic deformity was corrected to 13 degrees +/- 5 degrees, for a curve correction of 74%. Preoperative 23 degrees +/- 7 degrees of lumbar deformity was corrected to 2 degrees +/- 8 degrees, for a curve correction of 93%. Curve correction was not significantly affected by King type or distal fusion level (P > 0.05). Postoperative unsatisfactory results were obtained in 14 patients. When the preoperative NV was the same or one level distal to end vertebra (EV), fusion down to NV was satisfactory (14/14). When the preoperative NV was more than two levels distal to EV, fusion down to one level shorter than NV (NV-1) also was satisfactory (9/9). However, when fusion down to NV-2 or shorter was performed, the chances of adding on were higher (14/19; P < 0.01). Preoperative 17 degrees +/- 8 degrees of thoracic kyphosis was improved to 24 degrees +/- 7 degrees. In single thoracic idiopathic scoliosis, NV is an important factor for the determination of fusion level. When preoperative NV and EV show no more than two-level gap differences, the curve should be fused down to NV. When the gap is more than two levels, fusion down to NV-1 is satisfactory, saving one or two motion segments, as compared with fusion extending to the stable vertebra.

Crossed-screw fixation of the unstable thoracic and lumbar spine

An ideal spinal construct should immobilize only the unstable spinal segments, and thus only the segments fused. Pedicle fixation techniques have provided operative stabilization with the instrumentation of a minimal number of spinal segments; however, some failures have been observed with pedicle instrumentation. These failures are primarily related to excessive preload forces and limitations caused by the size and orientation of the pedicles. To circumvent these problems, a new technique, the crossed-screw fixation method, was developed and is described in this report. This technique facilitates short-segment spinal fixation and uses a lateral extracavitary approach, which provides generous exposure for spinal decompression and interbody fusion. The technique employs two large transverse vertebral body screws (6.5 to 8.5 mm in diameter) to bear axial loads, and two unilateral pedicle screws (placed on the side of the exposure) to restrict flexion and extension deformation around the transverse screws and to provide three-dimensional deformity correction. The horizontal vertebral body and the pedicle screws are connected to rods and then to each other via rigid crosslinking. The transverse vertebral body screws are unloaded during insertion by placing the construct in a compression mode after the interbody bone graft is placed, thus optimizing the advantage gained by the significant "toe-in" configuration provided and further decreasing the chance for instrumentation failure. The initial results of this technique are reported in a series of 10 consecutively treated patients, in whom correction of the deformity was facilitated. Follow-up examination (average 10.1 months after surgery) demonstrated negligible angulation. Chronic pain was minimal. The crossed-screw fixation technique is biomechanically sound and offers a rapid and safe form of short-segment three-dimensional deformity correction and solid fixation when utilized in conjunction with the lateral extracavitary approach to the unstable thoracic and lumbar spine. This approach also facilitates the secure placement of an interbody bone graft.

Organizing and Implementing an Ilizarov Program

The Ilizarov external fixator has made a profound impact on orthopaedic science. With its circular design, it allows correction of three-dimensional deformities including rotation, angulation, translation, shortening, and widening, as well as lengthening and soft tissue defects. Because this device is largely patient centered and patient operated, it has presented a new challenge and career investment for the orthopaedic nurse. A comprehensive Ilizarov program is necessary to address the total patient and his multiple needs in any facility where the Ilizarov method of treatment is adopted. The Ilizarov program is a multidisciplinary team approach that provides a structure for administering and providing total patient care for the Ilizarov patient and his significant other(s).

Limb lengthening and three-dimensional deformity corrections

Different methods of limb lengthening as used at the Orthopedic Surgery Clinic of the Medical School, University of Zagreb, are compared. The results of operations performed between 1979 and 1989 on 111 patients are presented. These patients were subjected to surgery aimed at length equalization of limbs and/or correction of three-dimensional deformities. Lengthening was performed in 104 patients at one level, and in 7 patients at two levels of the same limb for a total of 118 procedures. In order to compare limb lengthening techniques the patients were divided into four groups: group I, original Wagner technique (45 patients); group II, Wagner technique using corticotomy (33 patients); group III, original Ilizarov technique (35 patients); group IV, continuous lengthening (2 patients). The evaluation covered radiological aspects of regenerated bone, complications and basic lengthening parameters. The results indicate that corticotomy has considerable advantages over osteotomy, provided bone circulation is maintained. These advantages manifest themselves in a reduced number of operations, lower incidence of infection and improved bone regeneration. It is preferable to perform corticotomy at the metaphysis site because of its optimum blood supply and its higher potential for osteogenesis. With corticotomy performed at the diaphysis site, satisfactory results were observed in only one-third of the cases.