Matched Comparison of Magnetically Controlled Growing Rods with Traditional Growing Rods in Severe Early-Onset Scoliosis of ≥90°: An Interim Report on Outcomes 2 Years After Treatment

How do implants overlying the spine influence "The Law of Diminishing Returns" in early-onset scoliosis patients?

PURPOSE

The "law of diminishing returns" (LODR) in early-onset scoliosis (EOS) is well-known. We hypothesized that previously observed variations between constructs may be related to the lateral distance that each construct lies from the spine. We therefore sought to determine whether the curve magnitude improvement and spinal length gains for distraction-based constructs in EOS are positively correlated with the collinearity of the spine and the convex-sided implant on posteroanterior radiographs.

METHODS

A prospectively-collected, multicenter EOS registry was queried for all patients who underwent non-fusion, distraction-based instrumentation surgery. Post-index radiographs were graded from 1 to 5 based on amount of overlap between the convex-sided rod and the apical vertebra. Grade 1: convex rod is lateral to convex-sided pedicle; Grade 2: overlaps the convex-sided pedicle; Grade 3: lies between pedicles; Grade 4: overlaps concave-sided pedicle; Grade 5: medial to concave-sided pedicle. ANOVA assessed the correlations between post-index overlap grade and change in (a) curve magnitude and (b) T1-T12 height. Multivariable regression modeling further assessed these associations.

RESULTS

284 patients met all selection criteria and were included. On ANOVA, post-index grade was associated with curve magnitude (p <0.001) and T1-12 height (p = 0.028) change. Better curve correction and height change were associated with higher grade. On regression modeling, curve correction (R = 0.574) and T1-T12 height change (R = 0.339) remained significantly associated with grade when controlling for time, anchor locations, age, underlying diagnosis, and pre-index curve magnitude.

CONCLUSION

More apical overlap by the convex rod was associated with better spinal deformity control and improved height gain.

LEVEL OF EVIDENCE III

Therapeutic.

Complications and Health-Related Quality of Life in Children with Various Etiologies of Early-Onset Scoliosis Treated with Magnetically Controlled Growing Rods-A Multicenter Study

Background: Early-onset scoliosis (EOS) refers to spinal deformities that develop and are diagnosed before the age of 10. The most important goals of the surgical treatment of EOS are to stop the progression of curvature, achieve the best possible correction, preserve motion, and facilitate spinal growth. The objectives of this multicenter study were to analyze the risk of complications among patients with EOS treated using magnetically controlled growing rods (MCGRs) and assess the patients' and their parents' quality of life after diagnosis and treatment with a minimum two-year follow-up. Methods: Patients given an ineffective nonoperative treatment qualified for surgery with MCGRs. This study involved 161 patients (90 females and 71 males) who were classified according to the etiology of curvature. The intraoperative and postoperative complications and those that occurred during the continuation of treatment with MCGRs were recorded and analyzed. The 24-item Early-Onset Scoliosis Questionnaire (EOSQ-24) was used to evaluate the patients' quality of life and satisfaction with the treatment. Results: Implant-related complications requiring instrumentation revision were recorded in 26% of the patients. Medical complications occurred in 45% of the population. The EOSQ-24 revealed a significant improvement in the average scores during the follow-up. Conclusions: The treatment of early-onset scoliosis with MCGRs carries 66% risks of incurring medical and mechanical complications, the latter 26% of patients requiring revision procedures. Children with neuromuscular scoliosis, females, and with curvature greater than 90 degrees are at a higher risk of developing complications. Limiting the number of elective surgeries necessitated to prolong the instrumentation and treatment process for patients with MCGRs can greatly enhance their quality of life and satisfaction throughout the follow-up period.

Reliability and validity of the adapted Finnish version of the early onset scoliosis questionnaire (EOSQ-24)

BACKGROUND

EOSQ-24 is a disease specific patient-reported outcome score used to assess the quality of life in patients with early-onset scoliosis. The aim of this study was to translate and cross-culturally adapt the English version of the EOSQ-24 to Finnish language and to assess the reliability and validity of the translation.

METHODS

Cross-cultural adaptation and cross-cultural validation were performed to the Finnish translation of the EOSQ-24. Patients and/or their caretakers were then recruited to assess the psychometric properties of the translation. We assessed the internal consistency, test-retest reliability, floor and ceiling effects, and discriminative abilities. One-hundred-and-three patients filled the questionnaire.

RESULTS

EOSQ-24 was successfully translated into Finnish. The translation showed excellent internal consistency (Cronbach alpha 0.94), satisfactory item-total correlations ranging from 0.6 to 0.9, and moderate to strong inter item correlations. Test-retest reliability ranged from 0.7 to 0.96 indicating good to excellent agreement. Patients with neuromuscular and syndromic scoliosis reported lower EOSQ-24 scores when compared to patients' idiopathic and congenital scoliosis. There was a significant negative correlation between major curve and EOSQ-24 scores in patients with idiopathic early onset scoliosis.

CONCLUSION

The internal consistency and test-retest reliability of the measure were found to be satisfactory. A marked ceiling effect was observed, indicating a potential source of error.

Paediatric syndromic scoliosis: proceedings of the half-day course at the 57th annual meeting of the Scoliosis Research Society

There are some syndromes that present with unique manifestations pertaining to the spinal column. A good working understanding of these common syndromes is useful for the spinal deformity surgeons and related healthcare providers. This review attempts to encompass these unique features and discuss them in three broad groups: hypermobility syndromes, muscle pathology-related syndromes, and syndromes related to poor bone quality. This review explores the features of these syndromes underpinning the aspects of surgical and medical management. This review represents the proceedings of the Paediatric Half-Day Course at the 57th Annual Meeting of the Scoliosis Research Society.

Predictors of Rod Length Gain and Sagittal Alignment Change After Magnetically Controlled Growing Rod Lengthening

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

There are preoperative characteristics that predict rod lengthening of magnetically controlled growing rods (MCGR). The lengthening of MCGR will lead to increased kyphosis.

SUMMARY OF BACKGROUND DATA

The amount of length gained by MCGR is variable, and predictors are lacking. Similarly, sagittal plane changes over the MCGR lengthening period have not been investigated.

MATERIALS AND METHODS

Patients with MCGR and a minimum 2-year follow-up were identified and those with previous spine surgery were excluded. Preimplantation, postimplantation, and last follow-up postlengthening radiographs were examined. Multiple linear regression analyses were used for rod length gain predictors.

RESULTS

Fifty-six patients with early-onset scoliosis met inclusion criteria: nine idiopathic, five congenital, 14 neuromuscular, 20 syndromic, and eight skeletal dysplasia patients. No difference was seen between subtypes of early-onset scoliosis for rod length gain ( P =0.62). Shorter preoperative T1-T12 height and higher curve correction rate after implantation were significant predictors for rod length gain ( P <0.001). Preoperative major curve magnitude and kyphosis were not significant predictors. Flattening of the spine around the actuator and compensative increase in T1-T5 kyphosis were seen secondarily after MCGR implantation. Maximum sagittal kyphosis, T1-T5 kyphosis, and T5-T12 kyphosis did not change during lengthening. Lumbar lordosis significantly decreased postimplantation (first erect) but then increased during lengthening. Pelvic incidence and sacral slope both increased during lengthening, but this may be age related.

CONCLUSION

Patients who gained the most rod length with MCGR were those with an initially shorter T1-T12 height and better initial curve correction at implantation, likely representing that implants work best in small patients with flexible curves. Diagnosis, preoperative curve magnitude, and thoracic kyphosis were not related to rod length gain. Thoracic kyphosis did not deteriorate over the lengthening phase.

LEVEL OF EVIDENCE

Level III-retrospective cohort study.

Early-onset scoliosis

PURPOSE OF REVIEW

The aim of this review is to provide the reader with the most updated available information so that it can be helpful in the approach of patients with early-onset scoliosis (EOS).

RECENT FINDINGS

While confirming the efficacy and safety of classic techniques for the treatment of EOS such as traditional growing rods or Mehta casting, recent research suggests that there is room for improvement with less invasive techniques.

SUMMARY

The most important goal when treating patients with EOS should be to promote rib cage expansion and lung development. Different techniques have been described and may be used depending on the specific patient's characteristics.

Evaluating the Use of PROMs in Paediatric Orthopaedic Registries

Patient-reported outcome measures (PROMs) provide structured information on the patient's health experience and facilitate shared clinical decision-making. Registries that collect PROMs generate essential information about the clinical course and efficacy of interventions. Whilst PROMs are increasingly being used in adult orthopaedic registries, their use in paediatric orthopaedic registries is not well known. The purpose of this systematic review was to identify the frequency and scope of registries that collect PROMs in paediatric orthopaedic patient groups. In July 2023, six databases were systematically searched to identify studies that collected PROMs using a registry amongst patients aged under 18 years with orthopaedic diagnoses. Of 3190 identified articles, 128 unique registries were identified. Three were exclusively paediatric, 27 were majority paediatric, and the remainder included a minority of paediatric patients. One hundred and twenty-eight registries collected 72 different PROMs, and 58% of these PROMs were not validated for a paediatric population. The largest group of orthopaedic registries collected PROMs on knee ligament injuries (21%). There are few reported dedicated orthopaedic registries collecting PROMs in paediatric populations. The majority of PROMs collected amongst paediatric populations by orthopaedic registries are not validated for patients under the age of 18 years. The use of non-validated PROMs by registries greatly impedes their utility and impact. Dedicated orthopaedic registries collecting paediatric-validated PROMs are needed to increase health knowledge, improve decision-making between patients and healthcare providers, and optimise orthopaedic management.

Increasing soft tissue depth is associated with stalling of magnetically controlled growing rods

Background

Magnetically controlled growing rods (MCGR) represent the most used implant for the treatment of early onset scoliosis (EOS). These implants lengthen through the application of a remote magnetic field but distraction force generation has been negatively correlated with increasing soft tissue depth. Given the high rate of MCGR stalling, we proposed to investigate the impact of preoperative soft tissue depth on the rate of MCGR stalling at a minimum of 2 years following implantation.

Methods

A single-center, retrospective review of prospectively enrolled children with EOS treated with MCGR was performed. Children were included if they had a minimum of 2-years follow-up after implantation and underwent advanced spinal imaging (MRI or CT) preoperatively within a year of implantation. The primary outcome was the development of MCGR stall. Additional measures included radiographic deformity parameters and gain in MCGR actuator length.

Results

About 55 patients were identified with 18 having preoperative advanced imaging allowing tissue depth measurement (Mean 5.99 ± 1.9 years, 83.3% female, mean Cobb 68.6 ± 13.8°). At a mean follow-up of 46.1 ± 11.9 months, 7 patients (38.9%) experienced stalling. MCGR stalling was associated with increased preoperative soft tissue depth (21.5 ± 4.4 mm vs. 16.5 ± 4.1 mm; p = .025) and increased BMI (16.3 ± 1.6 vs. 14.5 ± 0.9; p = .007).

Conclusions

Greater preoperative soft tissue depth and BMI were associated with the development of MCGR stalling. This data supports previous studies showing that the distraction capacity of MCGR diminishes with increased soft tissue depth. Further research is needed to validate these findings and their implications on the indications for MCGR implantation.

The evolving stall rate of magnetically controlled growing rods beyond 2 years follow-up

PURPOSE

Magnetically controlled growing rods (MCGR) have become the dominant distraction-based implant for the treatment of early onset scoliosis (EOS). Recent studies, however, have demonstrated rising rates of implant failure beyond short-term follow-up. We sought to evaluate a single-center experience with MCGR for the treatment of EOS to define the rate of MCGR failure to lengthen, termed implant stall, over time.

METHODS

A single-center, retrospective review was conducted identifying children with EOS undergoing primary MCGR implantation. The primary endpoint was the occurrence of implant stalling, defined as a failure of the MCGR to lengthen on three consecutive attempted lengthening sessions with minimum of 2 years follow-up. Clinical and radiographic variables were collected and compared between lengthening and stalled MCGRs. A Kaplan-Meier survival analysis was conducted to assess implant stalling over time.

RESULTS

A total of 48 children met inclusion criteria (mean age 6.3 ± 1.8 years, 64.6% female). After a mean 56.9 months (range of 27 to 90 months) follow-up, 25 (48%) of children experienced implant stalling at a mean of 26.0 ± 14.1 months post-implantation. Kaplan-Meier survival analysis demonstrated that only 50% of MCGR continue to successfully lengthen at 2 years post-implantation, decreasing to < 20% at 4 years post-implantation.

CONCLUSION

Only 50% of MCGR continue to successfully lengthen 2 years post-implantation, dropping dramatically to < 20% at 4 years, adding to the available knowledge regarding the long-term viability and cost-effectiveness of MCGR in the management of EOS. Further research is needed to validate these findings.

Comparative efficacy and complications of single and dual growing rods for early-onset scoliosis: an updated meta-analysis

PURPOSE

This updated meta-analysis aimed to compare single and dual growing rods, including both traditional growing rod and magnetically controlled growing rod (MCGR) used in the treatment of early-onset scoliosis (EOS) with regard to deformity correction, spinal growth, and complications.

METHODS

This meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using articles extracted from PubMed, EMBASE databases, and Cochrane Library databases. Only articles reporting the complications and the imaging parameters before and after growing rods in the patients diagnosed with EOS were included. We extracted and statistically analyzed the data deemed relevant for this study, and used the Newcastle-Ottawa Scale to assess the risk of bias in each study. Data synthesis and statistical analyses were performed using R software.

RESULTS

Fifteen eligible articles containing 409 participants (n = 185, single growing rods; n = 224, dual growing rods) were identified. The meta-analysis found no significant differences in the preoperative and postoperative major Cobb angle, T1-S1 distance, thoracic kyphosis, and coronal balance between single and dual rods groups. The final follow-up major Cobb angle (P = 0.01; standardized mean difference, - 0.42 [95% confidence interval (CI), - 0.74 to - 0.10]; I² = 23%) was significantly smaller in dual rods group than single-rod group. However, no significant differences in the correction rate of angle (major Cobb angle and kyphosis angle) and changes in the T1-S1 distance between the two groups were observed. Moreover, there were no significant differences in the metalwork failure, infection, or proximal junctional kyphosis between single and dual rods groups. However, total complications (P = 0.03; risk ratio (RR), 0.79 [95% CI, 0.63-0.98]; I² = 29%) and distraction failure in MCGR (P = 0.04; RR, 0.38 [95% CI, 0.14-0.98]; I² = 11%) were significantly lower in dual rods group than single-rod group.

CONCLUSION

This updated meta-analysis found that patients with dual growing rods had fewer complications, especially distraction failure in MCGR, than those with single growing rod. However, none of deformity correction, spinal growth, or other complications differed between single and dual growing rods. Therefore, we believe that dual growing rods do not provide strong advantages over single growing rod in the treatment of EOS.

Lengthening Behavior of Magnetically Controlled Growing Rods in Early-Onset Scoliosis: A Multicenter Study

BACKGROUND

The "law of diminishing returns" is described for traditional growing rods. Magnetically controlled growing rods (MCGRs) have become a preferred implant for the surgical treatment of early-onset scoliosis (EOS). We examined a large cohort of patients with EOS to determine whether the law of diminishing returns applies to MCGRs.

METHODS

A prospectively collected, multicenter registry was queried for patients with EOS treated with MCGRs. Patients with only spine-based implants and a minimum of 2 years of follow-up were included; patients with congenital scoliosis, single rods, <3 lengthenings, or >25% missing data were excluded. Patients were analyzed in 3 cohorts: primary MCGR (pMCGR) had first-time MCGR implants, secondary MCGR (sMCGR) were converted from an MCGR to a new MCGR, and conversion MCGR (cMCGR) were converted from a non-MCGR implant to MCGR.

RESULTS

A total of 189 patients in the pMCGR group, 44 in the cMCGR group, and 41 in the sMCGR group were analyzed. From post-MCGR placement to the most recent follow-up or pre-definitive procedure, there were no differences in the changes in major Cobb angle, T1-S1 height, or T1-T12 height over time between the pMCGR and cMCGR groups. There was a decrease in length achieved at subsequent lengthenings in all cohorts (p < 0.01), and the sMCGR group had a significantly poorer ability to lengthen at each subsequent lengthening versus the pMCGR and cMCGR groups (p < 0.02). The 1-year survival rate was 90.5% for pMCGR, 84.1% for sMCGR, and 76.4% for cMCGR; 2-year survival was 61.5%, 54.4%, and 41.4%, respectively; and 3-year survival was 37.6%, 36.7%, and 26.9%, respectively. Excluding MCGRs still expanding, 27.6% of pMCGRs, 8.8% of sMCGRs, and 17.1% of cMCGRs reached the maximum excursion. Overall, 21.7% reached the maximum excursion. Within the pMCGR cohort, idiopathic and neuromuscular etiologies had a decline in lengthening achieved over time (p < 0.001), while syndromic EOS demonstrated a preserved ability to lengthen over time (p = 0.51). When the etiological groups were compared with each other, the neuromuscular group had the least ability to lengthen over time (p = 0.001 versus syndromic, p = 0.02 versus idiopathic).

CONCLUSIONS

The MCGR experiences the law of diminishing returns in patients with EOS. We found that only 21.7% of rods expanded to within 80% of the maximum excursion.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.