Use of the Universal Clamp in adolescent idiopathic scoliosis for deformity correction and as an adjunct to fusion: 2-year follow-up

Proximal Fixation in Adolescent Scoliosis Lenke 1 and 3 Treated by Posteromedial Translation Using Sublaminar Bands: Transverse-pedicular Hook Claw Versus Transverse Hook-pedicular Screw Claw

STUDY DESIGN

This is retrospective comparative study.

SUMMARY OR BACKGROUND DATA

Numerous studies have focused on the efficacy, safety, and restoration of thoracic kyphosis in adolescent idiopathic scoliosis surgery using posteromedial translation method with sublaminar bands and hook claws at the top. The relevance of exchanging the penultimate anchor, that is, the pedicle hook with a pedicle screw in a hybrid construction has not yet been assessed.

OBJECTIVE

Our objective was to assess, in adolescent scoliosis Lenke 1 and 3 operated by posteromedial translation using sublaminar bands, the proximal fixation claw influence (transverse-pedicular hook vs. transverse hook-pedicular screw) for postoperative correction and the proximal junctional kyphosis (PJK) at 2 years follow-up.

MATERIALS AND METHODS

A comparative monocentric retrospective study included adolescent idiopathic scoliosis thoracic requiring surgery, between 2015 and 2017, with 2 years follow-up. Clinical (complications, revision surgery, and scoliosis research society-30) and radiographic (coronal and sagittal parameters) assessment were reported. Radiologic PJK was defined by a proximal junctional angle increase of 10 degrees or more between postoperative period and the last follow-up.

RESULTS

Sixty patients (age at surgery=16±2 y; mean Cobb angle=58.2±12 degrees) were divided into 2 similar groups according to upper fixation: transverse-pedicular hook (H-H) and transverse hook-pedicle screw (S-H). No statistical differences were found for correction parameters (P>0.05). We reported 2 cases of PJK in H-H group (N=2/30=6.6%) and none in S-H group (N=0/30) (P=0.1) none requiring revision. No infectious or neurological events were reported. Mean scoliosis research society-30 was 126±12.7 in H-H group whereas 129.3±10 in S-H group (P=0.4).

CONCLUSIONS

No differences in postoperative correction and clinical results at 2 years follow-up were found. A claw with transverse-pedicular hook increase proximal junctional angle without significant increase on radiographic PJK incidence compared with a claw with transverse hook and pedicle screws.

Efficacy of polyester bands placed under the transverse vertebral process for the correction of adolescent idiopathic scoliosis : A case series of 105 patients with a minimum of 24 months follow-up

PURPOSE

To report an original technique for the surgical correction of adolescent idiopathic scoliosis (AIS) based on hybrid construct using polyester bands placed under the thoracic transverse processes.

METHODS

We reviewed 105 patients operated between 2013 to 2017 for AIS with a minimum of 2 years follow-up. Clinical and radiological data, including 2D measurements of scoliosis parameters preoperatively, and at 3- and 24-months postoperatively were analyzed. Radiological analysis was performed by two independent observers using KEOPS (Smaio, Lyon-France, CE 2014) database.

RESULTS

Mean age was 14.6 ± 2 years. Mean follow-up was 23.7 ± 1.2 months. Most curves were classified as Lenke-1 (78%). The average number of vertebra involved in the construct was 10.9 ± 1.3 (range 7-13). A mean of 12.8 implants were used per construct (mean implant density 0.59). The number of subtransverse bands placed averaged 3 (range 1-5 bands). The mean frontal Cobb angle decreased from 57.9 to 21.2 ° (p < 0.05) postoperatively. The average T4-T12 kyphosis increased from 20.2°to 32.4° (p < 0.05) postoperatively and no loss of correction was observed at 2 years follow-up. We encountered one case of transverse process fracture intraoperativley. No neurological complications were observed. In the postoperative period, 4 cases were diagnosed with distal junctional failure, three of which required an extension of the construct, while the fourth case was treated by bracing.

CONCLUSIONS

The use of subtransverse band is an efficient and safe method for the surgical correction of AIS. This technique incorporates technical ease (minimal risk of neurological injury), provides good frontal correction and restores thoracic kyphosis. Results are maintained over a two-year period.

Influence of the sublaminar band density in the treatment of Lenke 1 adolescent idiopathic scoliosis

INTRODUCTION

Optimal pedicle screw density for the treatment of adolescent idiopathic scoliosis (AIS) remains unknown. It is not clear whether higher implant density results in better clinical outcomes. Large variability in implant density exists among hybrid or all screw constructs. Significant heterogeneity exists with respect to the number of sublaminar bands (SB) used, and the influence of SB density on curve correction in the treatment of AIS.

HYPOTHESIS

We hypothesize that increased SB density does not improve sagittal or coronal plane curve correction.

METHODS

A single-center, retrospective study of 131 consecutive patients (118 females) with Lenke 1 adolescent idiopathic scoliosis, all operated between 2012 and 2015 by two surgeons using identical surgical technique and type of instrumentation (SB hybrid instrumentation treatment). SB density was measured using the number of SB reported as well as the number of vertebrae instrumented. Radiographic measurements included preoperative thoracic curve flexibility, Cincinnati reduction index (CRI), and postoperative thoracic Cobb (POCC) and kyphosis (POKC) angle correction measured on immediate postoperative radiographs and at 2 years postoperatively.

RESULTS

Median patient age was 15.6 years (IQR, 12-18). The median SB density was 0.4 (IQR 0.4-0.5). No statistically significant correlation was identified between SB density and CRI (p=0.71), POCC (p=0.55), or POKC (p=0.61) at 2-years postoperatively. Preoperative curve flexibility was found to have significant effect both on immediate (r=-3.02, p<0.001) and 2-year (r=-2.69, p<0.001).

DISCUSSION

SB utilized as a part of a hybrid construct for patients with flexible Lenke I AIS achieve satisfactory deformity correction regardless of SBd. The use of low SB density is appropriate for a subset of patients with flexible Lenke 1 adolescent idiopathic scoliosis.

USE OF SUBLAMINAR BANDS FOR ADOLESCENT IDIOPATHIC SCOLIOSIS - A SYSTEMATIC REVIEW

ABSTRACT Objective In 2003, Mazda et al. introduced a new device for surgical correction of Adolescent Idiopathic Scoliosis (AIS) called sublaminar bands (SB). The reduction principle that SBs use is posteromedial spinal translation, similar to Luque’s wiring, but using polyester bands. Methods We performed a systematic review of the literature on this subject, evaluating the technique in terms of coronal correction, sagittal correction, bleeding, mean surgical time, loss of correction, infection, pseudoarthrosis, and neurological and other complications. The total search resulted in 14 articles published over the last 10 years. We found that the use of SBs in hybrid AIS correction instrumentations provides an average correction of 69% in the frontal plane, a 5° increase in thoracic kyphosis (average increase of 55%), overall complications of 4.5%, and no neurological complications were reported in any of the studies analyzed.. The mean blood loss was 682.5 mL and the mean surgical time was 228.6 minutes. Conclusions We conclude that the literature suggests that this instrumentation is safe, allows good correction in the frontal plane and great correction in the sagittal plane. As for complications, mean surgical time, and blood loss, their averages are lower than those of other constructions used for AIS. Level of evidence IIA; Systematic review.

Sublaminar polyester bands for the correction of idiopathic and neuromuscular scoliosis

Recent literature suggests that sublaminar bands (SB) can provide good coronal plane correction, comparable to pedicle screw constructs, as well as good correction in the sagittal plane, even in patients with preoperative hypokyphosis; comparable results have been reported in patients with adolescent idiopathic scoliosis (AIS) and in patients with neuromuscular scoliosis (NMS). Two types of SB constructs can be performed: the band-only construct, indicated for non-ambulatory patients with NMS, and the hybrid construct indicted for ambulatory patients with NMS and for patients with AIS. SB are made of polyester or acrylic material and do provide a safe alternative to sublaminar Luque-type wires (stainless steel) as well as an increased contact area between SB and bone allowing higher corrective forces and reduced laminar fracture risk; the use of SB is not associated with increased risk of neurological injury nor with an increased risk of deep postoperative infection. SB used in a hybrid or in a band-only construct in patients with AIS and NMS, appear to be safe in a trained surgeon hands and can achieve well-balanced spine in both coronal and sagittal planes. This article aimed to provide a review of how SB can restore normal frontal and sagittal spine alignment in patients with AIS and NMS.

Over 70° thoracic idiopathic scoliosis: Results with screws or hybrid constructs

BACKGROUND

Adolescent idiopathic scoliosis is the most common type of scoliosis. High degrees curve can be treated with the anterior, posterior, or combined anterior-posterior approach. Contrarily to the anterior approach, the posterior one is widely used nowadays for its good correction outcomes and relatively low-complication rate.

MATERIALS AND METHODS

We evaluated retrospectively 27 patients, treated with posterior approach. Patients were divided into two groups, namely pedicle screws group (PSG) and hybrid group (pedicle screws + sublaminar bands). Radiographic measurements, including thoracic and lumbar Cobb° measurements of primary and secondary curves, coronal balance and sagittal balance, kyphosis and lordosis, curve flexibility, first and last vertebra included in the arthrodesis, and implant density were evaluated. Clinical patients' satisfaction was also evaluated with Scoliosis Research Society (SRS) 24 questionnaire.

RESULTS

Considering both groups, on preoperative X-rays, the average primary scoliotic curve angle was 83.56° ± 10.96° (range 70°-112°), whereas the global flexibility was 64° ± 7.63 (range 46°-72°). The curves were classified following the Lenke classification: 17 Type 1, 2 Type 2, and 8 Type 3. The primary curve resulted to be well corrected in both groups. In T0, the groups were homogeneous, but in T1 and follow-up, PSG stated a better mean value. No other significative differences can be found between groups for all other items (P > 0.05). Clinical results of SRS 24 were excellent in both groups.

CONCLUSIONS

The posterior approach proved to be an excellent technique for obtaining good clinical and radiographic results if the surgeon adopts the third-generation high-density implants.

LEVEL OF EVIDENCE

III.

Do Sublaminar Polyester Bands Affect the Outcomes of Postoperative Infections After Adolescent Idiopathic Scoliosis Surgery?

BACKGROUND

The incidence of surgical site infections (SSI) after adolescent idiopathic scoliosis (AIS) surgery ranges from 0.5% to 7%. There is currently a regain of interest in hybrid constructs, combining lumbar pedicle screws and thoracic sublaminar bands, but some authors have raised concerns about the risk of SSI and the difficulty of bacterial eradication. The goal of this study was therefore to assess the outcomes of SSI after AIS surgery using sublaminar bands.

METHODS

A total of 524 consecutive patients operated for AIS using sublaminar bands between June 2006 and June 2014 were included. SSI cases were identified and analyzed retrospectively. Radiologic and functional outcomes were evaluated at follow-up using EOS imaging and SRS 30 scores, and compared with a control group.

RESULTS

The overall SSI rate was 5.3%, with a majority of monomicrobial (86%) infections occurring in the first 6 weeks postoperative (93%). The most frequent pathogens were skin germs (Staphylococcus aureus and Propionibacterium acnes) with a community profile. Patients were treated successfully with surgical debridement without implants removal, associated with 6 weeks of antibiotherapy. However, 25% of patients required >1 surgical debridement. Instrumentation removal was decided in the 2 cases with late SSI, and performed uneventfully. Radiologic and functional outcomes at follow-up were not affected by the occurrence of SSI.

CONCLUSIONS

Sublaminar bands are not associated with a higher risk of infection. However, the SSI rate in the current study stands in the upper range of the literature, and other preventive strategies should be considered. In case of early infection, bands removal is not necessary to obtain pathogen eradication, but the sublaminar implants can be pulled out safely in case of late SSI. The occurrence of SSI does not alter the outcomes at follow-up.

LEVEL OF EVIDENCE

Level III.

Radiopaque UHMWPE sublaminar cables for spinal deformity correction: Preclinical mechanical and radiopacifier leaching assessment

Polymeric sublaminar cables have a number of advantages over metal cables in the field of spinal deformity surgery, with decreased risk of neurological injury and potential for higher correction forces as the two most predominant. However, currently available polymer cables are radiolucent, precluding postoperative radiological assessment of instrumentation stability and integrity. This study provides a preclinical assessment of a woven UHMWPE cable made with radiopaque UHMWPE fibers. Our primary goal was to determine if the addition of a radiopacifier negatively affects the mechanical properties of UHMWPE woven cables. Tensile mechanical properties were determined and compared to suitable controls. Radiopacity was evaluated and radiopacifier leaching was assessed in vitro and in vivo. Finally, in vivo bismuth organ content was quantified after a 24-week implantation period in sheep. Results show that the mechanical properties of woven UHMWPE cables were not deleteriously affected by the addition of homogenously dispersed bismuth oxide particles within each fiber. Limited amounts of bismuth oxide were released in vitro, well below the toxicological threshold. Tissue concentrations lower than generally accepted therapeutic dosages for use against gastrointestinal disorders, well below toxic levels, were discovered in vivo. These results substantiate controlled clinical introduction of these radiopaque UHMWPE cables. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 771-779, 2018.

Comparison of Clinical and Radiologic Outcome of Adolescent Idiopathic Scoliosis Treated with Hybrid Hook-Screw Instrumentation versus Universal Clamp System

Background. In surgical treatment of adolescent idiopathic scoliosis (AIS), hybrid universal clamp system has been used by some authors. We aimed to compare the clinical and radiologic outcome of hybrid universal clamp with hybrid thoracic hook lumbar screw. Methods. A prospective study was performed on 56 consecutive patients with AIS, who had alternatively undergone a posterior spinal fusion and instrumentation with hybrid thoracic hook lumbar screw system (28 patients: group A) and hybrid universal clamp system (28 patients: group B) between June 2006 and January 2014 at Imam Reza University Hospital and had been followed up for more than two years. The comparison was according to radiographic changes, operative time, intraoperative blood loss, complications, and Scoliosis Research Society (SRS-22) outcome scores. Results. The preoperative mean curve Cobb angle was 58° ± 7° (42°-74°) in group A and 60° ± 9° (46°-75°) in group B. The mean final coronal curve correction was 60.4% and 75.5% in groups A and B, respectively (P = 0.001). Postoperative SRS outcome scores were also comparable. Conclusion. Universal clamp instrumentation had a significantly better curve correction and lower complication rate compared with hybrid thoracic hook lumbar screw. Both instrumentation methods had similar operative time, intraoperative blood loss, and postoperative SRS outcome scores.

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.

Adolescent idiopathic scoliosis correction achieved by posteromedial translation using polyester bands: A comparative study of subtransverse process versus sublaminar fixation

PURPOSE

Sublaminar polyester bands have been used in hybrid construct to achieve correction of adolescent idiopathic scoliosis since 2003. Despite the reported safety of the bands, some surgeons remain reluctant at the idea of approaching the canal because of the potential neurological complications reported with the Luque wiring. Sub transverse bands might be an alternative. The present study is the first to compare sublaminar polyester band fixation to fixation of polyester bands around the transverse processes in hybrid constructs used to treat AIS.

METHODS

Two cohorts of consecutive patients treated for thoracic AIS were retrospectively reviewed, with a minimum 2-year follow-up. Posteromedial translation was used for main curve correction in all cases. Sublaminar polyester bands were used in group 1 (20 patients). In group 2 (20 patients), the same implant was used, but the bands were passed around the transverse process instead of the lamina. Radiographic analysis included frontal Cobb angle measurements for each curve, thoracic kyphosis and rotation of the apical vertebra (RVA).

RESULTS

Mean operative time was similar in groups 1 and 2 (235±35 and 240±30minutes, respectively). Mean frontal correction achieved for the main curve was similar in both groups, 62.5±17.4% in group 1 and 54.1±19.4% in group 2. Sagittal correction was similar, with a final mean thoracic kyphosis of 30.9°±9.7° and 27.8°± 6.8° in group 1 and 2, respectively. Correction of RVA was similar in both groups postoperatively, 65.8% (±29.1) and 54.4% (±42.7) in group 1 and 2 respectively. No transverse process or lamina fracture was observed during insertion of the bands or curve correction in any of the groups.

CONCLUSION

This study confirms that anchorage of Universal clamps (UCs) around transverse processes is a safe and efficacious technique in both the frontal and sagittal planes, providing a useful alternative for the correction of moderate AIS. UCs attached to transverse processes can achieve correction of moderate AIS similar to that obtained with sublaminar UCs while further reducing risks of vertebral canal complications.

LEVEL OF EVIDENCE

Level IV.

The Universal Clamp hybrid system: a safe technique to correct deformity and restore kyphosis in adolescent idiopathic scoliosis

PURPOSE

Adolescent idiopathic scoliosis (AIS) is a tridimensional deformity characterized by coronal and sagittal profiles changes. We present a series of 62 patients affected by AIS and treated by thoracic Universal Clamps and transpedicular lumbar screws hybrid system.

METHODS

Mean age was 13 years. Average pre-operative Cobb angle was 63° ± 12°. Patients were divided into two groups depending on the kyphosis angle: lower than 45° (51 patients, 82.3 %, mean 21° ± 3°) and higher than 45° (11 patients, 17.7 %, mean 62° ± 6°).

RESULTS

The average percentage of coronal correction was 70 ± 3 % (mean post-operative Cobb angle 19° ± 4°, P < 0.001). In patients with pre-operative physiological thoracic kyphosis-hypokyphosis, we observed an increase in the average value (32° ± 4°, P < 0.001), while in patients with pre-operative hyperkyphosis, mean decrease of thoracic kyphosis was 19° ± 3° (43° ± 4°, P < 0.001).

CONCLUSIONS

This case-series study showed the efficacy and safety of Universal Clamp hybrid system in correcting coronal deformity and restoring physiological thoracic kyphosis in patients affected by AIS.

Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system

PURPOSE

Computed tomography can be used for three-dimensional (3D) evaluation of adolescent idiopathic scoliosis (AIS) patients, but at the expense of high radiation exposure, and with the limitation of being performed in the supine position. These drawbacks can now be avoided with low-dose stereoradiography, even in routine clinical use. The purpose of this study was to determine the 3D postoperative correction of AIS patients treated by posteromedial translation.

METHODS

Forty-nine consecutive patients operated for AIS (Lenke 1-4) using posteromedial translation were included. Corrections were evaluated preoperatively, postoperatively and after at least 2 years using the EOS imaging system. 3D angles were measured in the plane of maximum deformity.

RESULTS

Mean number of levels fused and operative time were 13.5 ± 1 and 215 ± 25 min, respectively. Main thoracic, proximal thoracic, and lumbar curves corrections averaged 64.4 ± 18, 31 ± 10 and 69 ± 20 %, respectively. Mean T4-T12 kyphosis increased 18.8° ± 9° in the subgroup of hypokyphotic patients. Mean apical vertebral rotation reduction was 48.3 ± 20 %. Trunk height gain averaged 27.8 ± 14 mm. There was no pseudarthrosis or significant loss of correction in any plane during follow-up. Two patients (4 %) developed asymptomatic proximal junctional kyphosis, despite having normal thoracic kyphosis. Their sagittal balance was shifted posteriorly by 36 and 47 mm, respectively, by the operation, but revision surgery was not performed.

CONCLUSIONS

Low-dose stereoradiography provided 3D reconstructions of the fused and unfused spine in routine clinical use. Postoperative 3D analysis showed that posteromedial translation enhanced sagittal balance correction, without sacrificing frontal or axial correction of the deformity.

Sagittal profile control in patients affected by neurological scoliosis using Universal Clamps: a 4-year follow-up study

PURPOSE

Patients affected by cerebral palsy often develop progressive scoliosis that can results in trunk instability with an impairment of both coronal and sagittal balance. The aim of this retrospective study was to demonstrate the ability of UC to control the sagittal profile in a consecutive series of patients affected by neurological scoliosis.

METHODS

From 2006 to 2008, 84 patients (57 F, 27 M) affected by neurological scoliosis were treated surgically. Mean age was 14 years (range 10-17). The etiology was mainly cerebral palsy. The average pre-operative Cobb angle was 73° ± 16°. Patients were divided into three groups according to the pre-operative presence of: physiological kyphosis (mean 29° ± 8°), thoracic lordosis (mean 10° ± 6°) and hyperkyphosis (51° ± 8°). A posterior access was performed in all patients using thoracic UC associated with transpedicular lumbar screws and a conventional claw at the upper extremity of the construct.

RESULTS

The average percentage of coronal correction was 72%. In all three groups, we observed a common trend toward maintaining or restoring the physiological values. Mean follow-up time was 36 months. At the 1-year follow-up, the mean loss of correction was 7° ± 2° in the coronal plane and 2° ± 1° in the sagittal plane with no other change thereafter.

CONCLUSIONS

The hybrid construct using UC appears effective in neurological scoliosis treatment, providing a good correction of the deformity in both coronal and sagittal planes. In the present series, physiological thoracic kyphosis has been restored in all patients, providing better sitting tolerance in wheelchair-bound patients, and retaining standing and walking abilities in ambulatory patients.