X-ref For other Roundups in this issue that cross-reference with Children’s orthopaedics see: Spine Roundup 8
Scoliosis management in patients with Duchenne’s
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In this valuable look back from San Diego, California (USA), the authors present 30 years of a single institution’s experience in treating spinal deformities in children with Duchenne muscular dystrophy (DMD).1 The complexities of treating scoliosis in patients with muscular dystrophy are well known; however, there are few long-term series on which to inform clinical practice, particularly when contemplating surgery. In this 30-year retrospective series, the authors were able to identify 60 patients, all with DMD, treated operatively for their scoliosis. There was a mixture of operative techniques, as one would expect with such a long-term follow-up series. Of the 60 reported patients, 47 were treated using the Luque wire constructs and the remaining 13 were treated using a posterior pedicle screw construct. In the Luque group, there was a high rate of intraoperative and postoperative complications, with an overall complication rate of 68% (n = 31/47). A total of 12 patients (26%) had implant-related complications and an overall 4% infection rate was found. In contrast, the pedicle screw group (although much smaller) reported an overall 54% complication rate (n = 6/13), with only a single (8%) implant-related complication in the form of proximal junctional kyphosis, with no need for revision at final follow-up. The infection rate in the pedicle screw group was very high, at 23% (three patients). Although the authors attempt to draw comparisons between the two instrumentation types, the pedicle screw group really is so small that there is little of use that can be gleaned from this comparison. Nonetheless, this review does demonstrate a clear transition from Luque instrumentation to pedicle screw instrumentation in the mid-2000s. There is also a noticeable trend in this group’s practice towards increased fixation to the pelvis using pedicle screw constructs, with good arguments presented by the authors for the need to avoid progression of pelvic obliquity and the potential for subsequent surgeries. There was also a change in practice with regard to the timing of surgery, and the series is notable in that there was a trend towards delaying treatment in the pedicle screw group, as the more recent patients treated using pedicle screw constructs were older and heavier with larger preoperative Cobb angles.
Preliminary results of magnetically controlled growing rods for early-onset scoliosis
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Magnetically controlled growing rods have been developed to offer the potential for better control of growth in paediatric scoliosis. The constructs offer the tempting scenario of controlled growth in a more continuous manner without the need for a second, smaller surgery to lengthen the rods, as has previously been necessary. There have been a number of small case series and case reports of complications; however, we were delighted to see this report of a large number of cases giving an overview of what one can expect from such implants. A team from Hamburg (Germany) presents their results using magnetically controlled growing rods (MCGRs) to treat patients with progressive early-onset scoliosis (EOS).2 Magnetically controlled growing rods have been in use for about four years now (Food and Drug Administration approval in February 2014, USA), and the preliminary reports are slowly coming in. The MCGR allows gradual outpatient distractions under the control of an external remote device. The attraction of the approach is that the standard familiar operative technique can be used but with a growing rod between the pedicle screws. These authors report on their first consecutive 35 patients treated using this technique, with 24 patients meeting the inclusion criteria for the study (minimum 12-month follow-up and four or more lengthening episodes). In terms of surgical correction achieved – within this cohort, at least – the authors were able to report a 54% immediate correction of scoliosis after surgery. Prior to surgery, the mean primary curve was 63° (sd 15°; range 40° to 96°), which had improved to 29° (sd 11°; range 11° to 53°) immediately postoperatively after MCGR. The mean preoperative thoracic kyphosis decreased from 43° (sd 24°; range -32° to 86°) to 27° (sd 12°; range 9° to 50°) after surgery. This was maintained throughout the follow-up period, with a mean major curve of 26° after the most recent lengthening. With regard to thoracic height, there was a statistically significant constant increase in T1 to T12 length and T1 to S1 height over the course of the reported follow-up period, suggesting that the magnetic rods themselves are working and allowing for growth. There were no reported intraoperative complications and only a single postoperative complication requiring a revision with exchange of the rod. There were no infections, rod breakages, or neurological complications. The authors here conclude that MCGR is a safe technique that produces predictable results while at the same time significantly reducing the risk of infection seen in traditional growing rod techniques.
Tranexamic acid to reduce transfusion requirements in paediatric scoliosis surgery
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With more than half of scoliosis patients needing blood transfusions after surgical correction, strategies are constantly being devised and improved to amend this. There has been widespread use of tranexamic acid (TXA) in all branches of orthopaedic and general surgery, with reports of efficacy in conditions as diverse as blunt trauma and hip and knee arthroplasty. Tranexamic acid is not widely used in children, however, and in many countries is not licensed for paediatric use. The authors of this study from Baltimore, Maryland; New York, New York; and Boston, Massachusetts (USA) compared two dosing regimens (low and high dose) of TXA in order to reduce intraoperative blood loss during paediatric scoliosis surgery.3 The efficacy of TXA has been hypothesized to be dose-dependent, but so far there has been no consensus on the best dosing regimen in adults, let alone in children. The two dosing regimens investigated in retrospect were the low dose (72 patients) of 10 mg/kg loading dose and a 1 mg/kg/h maintenance dose; and the high dose (44 patients) of 50 mg/kg loading dose and a 5 mg/kg/h maintenance dose. Patient characteristics were nearly identical between the two groups. Compared with the low-dose TXA group, the high-dose TXA group had decreased estimated blood loss (695 ml vs 968 ml, p = 0.01), and a decrease in red blood cell transfusion requirements both intraoperatively (0.3 units vs 0.9 units, p = 0.01) and over the course of the whole hospitalization (0.4 units vs 1.0 units, p = 0.04). The higher-dose TXA was associated with decreased intraoperative and postoperative transfusion requirements, even after risk adjustment for potential confounding variables. The high-dose group had significantly less intraoperative blood loss (≈ 30%) and a decreased red blood cell transfusion requirement (≈ 60%) when compared with the low-dose group. The authors argue that TXA dosage schemes used in studies in the available literature are not based on the pharmacokinetics of TXA, as such studies have not yet been conducted in the paediatric orthopaedic population. To maximize efficacy and minimize side effects, guidelines should be based on pharmacokinetic data and pharmacokinetic modelling to ensure that the minimally effective dosage scheme is recommended, which is clearly the ideal case. Until these data are available, it would seem that some of the best applicable data are in this study and that the authors’ ‘high-dose’ regime is probably the benchmark.
Performing a definitive fusion in juvenile cerebral palsy patients is a good surgical option
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The management of cerebral palsy (CP) children takes up a substantial proportion of paediatric orthopaedic surgical time and effort. The combination of cognitive difficulties and often progressive selective spasticity causes well-described problems in the hips, feet, and spine. The progressive neuromuscular spinal deformities seen in children with CP are not only common (with the overall incidence reported at between 20% and 25%) but almost ubiquitous in spastic quadriplegic patients, with a reported incidence of 74%. The challenge to managing this progressive condition is that the addition of progressive and differential muscle pulls with a growing spine results in a high failure rate of instrumentation. For this reason, there is an increasing propensity to fuse the spine early to prevent later progressive deformity. This study from San Diego, California (USA) evaluates the outcomes of early definitive spinal fusion in patients with juvenile cerebral palsy scoliosis.4 Fusing early raises concerns of an ultimately shorter trunk or progression of spinal deformity and pelvic obliquity by means of the ‘crankshaft’ phenomenon. These authors present a small series of 14 CP children who underwent spinal fusion at the age of ten years and younger (skeletally immature). All but one of these patients were fused to the pelvis to reduce the risk of the crankshaft phenomenon. The authors report that, by the first follow-up examination, there was a mean 71% correction rate of scoliosis and an 84% correction rate of pelvic obliquity across this small group of patients. During the subsequent two-year follow-up, the authors report some slight losses of correction in both the main curve and pelvic obliquity; however, this was a relatively minor loss of correction and none of the patients required revision surgery due to deformity progression during this period. The authors postulate that it is possible that the long construct secured to the pelvis, combined with the slower growth typically seen with CP patients, may lessen the risk of crankshaft. Despite the small numbers of patients in this study, the authors draw the very sensible conclusion that “progressive scoliosis in juvenile CP patients requires the surgeon to balance the need for further growth with the risks of progression or repeated surgical procedures. Our study demonstrates that definitive fusion once the curves approach 90 degrees results in significant radiographic and quality of life improvements”.
MRI as reliable and reproducible as CT in assessing paediatric hips
MRI scanning is not associated with any radiation and is therefore an attractive imaging modality in children. However, due to the method of image acquisition (roughly measuring the release in energy following excitation of hydrogen-dipoles secondary to a radio frequency pulse in a magnetic field), bony architecture is not as well visualized as it is with CT, and multiplanar reconstruction following acquisition is not possible. In order to take advantage of the reduced radiation burden associated with MRI scanning, femoral version measurement techniques have been developed. However, there are few validation studies and, as such, the accuracy of this diagnostic modality is not established. We reported on a paper validating the MRI scan following operative reduction in hip dysplasia in the last edition of 360,5 and hot on the heels of this paper comes a report from authors in Aurora, Colorado (USA) who undertook a diagnostic accuracy study with the aim of establishing whether MRI alone could be used, and what the reliability, repeatability, and accuracy of MRI-based femoral neck version measurements are in the paediatric population.6 The study focuses on a cohort of patients who underwent MRI scanning with a delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) protocol. The mean age for the cohort of 36 patients that formed the basis for this study was 15 years. There was a comparative interrater reliability for the CT and MRI protocols (0.91 vs 0.90) and a comparative intrarater reliability (0.96 vs 0.95), with highly concordant measurements in terms of femoral neck version. Essentially, these authors found that axial images at the pelvis and knee during MRI allow for reliable measurement of femoral version. The use of a rapid sequence acquisition MRI protocol also removes one of the drawbacks of MRI scanning in children, namely the requirement to stay stationary for a significant period of time.
Radial dysplasia: what is the optimal treatment?
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Radial dysplasia is a relatively common condition affecting around 1 in 7000 births. The appearance of a shortened dysplastic radius with a bowed ulna and radially deviated hand is the classic presentation. Despite the comparatively common presentation, there is a still a lot of debate and a lack of clarity as to what constitutes optimal treatment. This prompted a team in London (UK) to undertake an extensive systematic review to clarify the long-term outcomes of surgical and nonsurgical treatment of the wrist (secondary) deformity.7 The review team carried out a comprehensive search of the indexed medical literature and, in addition, queried the trials registries at ClinicalTrials.gov and the World Health Organization (WHO) Clinical Trials Registry Platform, searching for both published and unpublished studies reporting long-term outcomes for patients treated for radial dysplasia. There were 104 studies identified in the initial search, 12 of which were included in this review after screening. The usual GRADE method (Grades of Recommendation, Assessment, Development, and Evaluation) was used to assess the studies, and results were pooled for the change in forearm angle. Primary outcomes including range of motion (ROM) and clinical outcome scores were also subject to meta-analysis. The major finding of this study was that the hand-forearm angle worsened in patients who received nonsurgical treatment (from 66° to 84°), while the various surgical approaches achieved different outcomes. The analysis of the available data would suggest that soft-tissue distraction with centralization or radialization procedures yielded the best achievable hand-forearm angle correction at 16°. In terms of wrist motion, the radialization option gave best active wrist motion at 46°. An improved wrist ROM could be achieved with a complex microvascular second metatarsophalangeal joint transfer yielding a better active ROM at 83°. Although the quality of evidence here is somewhat compromised by a range of biases, the inherent limitations in the study designs, and the small numbers of patients, what evidence there is would suggest that soft-tissue distraction plus centralization or radialization is likely to achieve the best hand position in radial dysplasia.
Clicky hips: to scan or not to scan?
The traditional clinical screening tests applied to all neonates and six-week-old babies in order to establish whether a hip is dislocated and reducible, or in joint and dislocatable, are the Ortolani’s and Barlow’s tests. These have previously been demonstrated to have only moderate diagnostic accuracy; consequently, in most healthcare systems, babies with risk factors or with either a positive Ortolani or positive Barlow test are usually referred for ultrasound scanning. There are also specialist referrals commonly made for so-called ‘clicky hips’. The actual diagnostic value of a clicky hip is unclear, and without this information it is uncertain whether patients with a clicky hip should continue to be referred. The paediatric team in Blackburn (UK) have attempted to determine the clinical significance of a clicky hip.8 They report a 20-year prospective study of their one-stop paediatric hip clinic and report the clinical significance of a clicky hip in 362 infants referred over a 20-year period. All hips were assessed both through clinical examination and ultrasound imaging. The mean age at presentation was 14 weeks and the cohort consisted overwhelmingly of normal Graf type I hips (97%, n = 351/362), requiring no treatment or follow-up. Of the remaining 11 children, nine (2.5% of the total cohort) had Graf type II hips, all resolving on follow-up scans. There were just two children requiring treatment: one with Graf type III hip dysplasia and one child with an irreducible hip dislocation. Given the large number of patients in this cohort (nearly 400), the very low specificity (0.5%), and the unknown sensitivity of the clinically clicky hip, we would agree with the authors of this paper – only a strong family history or positive ‘special’ tests should trigger a referral to a specialist paediatric service, and not clicky hips alone.
References
1 Scannell BP , Yaszay B , Bartley CE , Newton PO , Mubarak SJ . Surgical correction of scoliosis in patients with Duchenne muscular dystrophy: 30-year experience. J Pediatr Orthop2017;37:e464-e469.CrossrefPubMed Google Scholar
2 Ridderbusch K , Rupprecht M , Kunkel P , Hagemann C , Stücker R . Preliminary results of magnetically controlled growing rods for early onset scoliosis. J Pediatr Orthop2017;37:e575-e580.CrossrefPubMed Google Scholar
3 Johnson DJ , Johnson CC , Goobie SM et al. . High-dose versus low-dose tranexamic acid to reduce transfusion requirements in pediatric scoliosis surgery. J Pediatr Orthop2017;37:e552-e557.CrossrefPubMed Google Scholar
4 Yaszay B , Sponseller PD , Shah SA et al. . Performing a definitive fusion in juvenile CP patients is a good surgical option. J Pediatr Orthop2017;37:e488-e491.CrossrefPubMed Google Scholar
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