Bernard Herbaux

Three-dimensional measurements of the lower extremity in children and adolescents using a low-dose biplanar X-ray device

AbstractObjectiveTo evaluate three-dimensional (3D) measurements of the lower extremity using a biplanar low-dose X-ray device in children and adolescents.MethodsFirstly, 3D measurements of eight dried bones were analysed by a biplanar low-dose X-ray device (LDX) using stereoscopic software and compared with 3D computed tomography (CT). Secondly, 47 lower limbs of children and adolescents were studied using LDX two-dimensional (2D) and 3D measurements. Both parts were evaluated for femoral and tibial lengths and mechanical angles, frontal and lateral knee angulations, and the femoral neck-shaft angle.ResultsThe 3D specimen comparison between LDX and CT measurements showed no significant differences: femoral length (P = 0.069), tibial length (P = 0.059), femoral mechanical angle (P = 0.475), tibial mechanical angle (P = 0.067), frontal knee angulation (P = 0.198), lateral knee angulation (P = 0.646) and femoral neck-shaft angle (P = 0.068). The comparison between LDX 2D and 3D measurements showed significant differences in tibial length (P = 0.003), femoral mechanical angle (P < 0.001) and femoral neck-shaft angle (P = 0.001); other parameters were unremarkable.ConclusionsThe 3D LDX system presented reliable measurements compared with 3D CT. Differences between LDX 2D and 3D measurements were noted in the femoral mechanical angle, femoral neck-shaft angle and tibial length. Moderate to good interobserver agreement for the 3D LDX measurements were found.Key Points• Low radiation dose is essential when assessing potential lower extremity discrepancies • A new biplanar low-dose X-ray device can assess such discrepancies in children/adolescents • This LDX device provides equally reliable 3D measurements as prevalent practice LDX measurements carry good overall interobserver agreement.

Complications in pediatric spine surgery using the vertical expandable prosthetic titanium rib: the French experience.

Study Design. Multicenter retrospective study of 54 children. Objective. To describe the complication rate of the French vertical expandable prosthetic titanium rib (VEPTR) series involving patients treated between August 2005 and January 2012. Summary of Background Data. Congenital chest wall and spine deformities in children are complex entities. Most of the affected patients have severe scoliosis often associated with a thoracic deformity. Orthopedic treatment is generally ineffective, and surgical treatment is very challenging. These patients are good candidates for VEPTR expansion thoracoplasty. The aim of this study was to evaluate the potential complications of VEPTR surgery. Methods. Of the 58 case files, 54 were available for analysis. The series involved 33 girls and 21 boys with a mean age of 7 years (range, 20 mo–14 yr and 2 mo) at primary VEPTR surgery. During the follow-up period, several complications occurred. Results. Mean follow-up was 22.5 months (range, 6–64 mo). In total, 184 procedures were performed, including 56 VEPTR implantations, 98 expansions, and 30 nonscheduled procedures for different types of complications: mechanical complications (i.e., fracture, device migration), device-related and infectious complications, neurological disorders, spine statics disturbances. Altogether, there were 74 complications in 54 patients: a complication rate of 137% per patient and 40% per surgery. Comparison of the complications in this series with those reported in the literature led the authors to suggest solutions that should help decrease their incidence. Conclusion. The complication rate is consistent with that reported in the literature. Correct determination of the levels to be instrumented, preoperative improvement of nutritional status, and better evaluation of the preoperative and postoperative respiratory function are important factors in minimizing the potential complications of a technique that is used in weak patients with complex deformities. Level of Evidence: 4

Prevalence and clinical significance of occult fractures in children with radiograph-negative acute ankle injury. A meta-analysis.

Background and purpose — Plain radiographs may fail to reveal an ankle fracture in children because of developmental and anatomical characteristics. In this systematic review and meta- analysis, we estimated the prevalence of occult fractures in children with acute ankle injuries and clinical suspicion of fracture, and assessed the diagnostic accuracy of ultrasound (US) in the detection of occult fractures. Methods — We searched the literature and included studies reporting the prevalence of occult fractures in children with acute ankle injuries and clinical suspicion of fracture. Proportion meta-analysis was performed to calculate the pooled prevalence of occult fractures. For each individual study exploring the US diagnostic accuracy, we calculated US operating characteristics. Results — 9 studies (involving 187 patients) using magnetic resonance imaging (MRI) (n = 5) or late radiographs (n = 4) as reference standard were included, 2 of which also assessed the diagnostic accuracy of US. Out of the 187 children, 41 were found to have an occult fracture. The pooled prevalence of occult fractures was 24% (95% CI: 18–31). The operating characteristics for detection of occult ankle fractures by US ranged in positive likelihood ratio (LR) from 9 to 20, and in negative LR from 0.04 to 0.08. Interpretation — A substantial proportion of fractures may be overlooked on plain radiographs in children with acute ankle injuries and clinical suspicion of fracture. US appears to be a promising method for detection of ankle fractures in such children when plain radiographs are negative.

Assessment of micro-dose biplanar radiography in lower limb measurements in children

AbstractObjectivesTo evaluate in children microdose protocol compared with low dose for lower limb alignment (LLA) measurements on biplanar radiography.MethodsChildren 6 years or older were included. Height, weight and hip width were measured prior to imaging. Hip width allowed classifying children into morphotype M1 (width <25 cm), M2 (25–35 cm) or M3 (>35 cm) corresponding to predefined acquisition parameters (kV, mA, tube speed). Micro- and low-dose protocols were used alternately, with simultaneous acquisition of frontal and lateral radiographs. LLA measurements were performed by two independent observers (n = 526). In 15 children per morphotype, a third observer performed measurements twice (n = 180). Intraclass correlation coefficients and the dose (delivered, absorbed) were calculated.Results100 girls and 160 boys (mean age = 11.7 years) were investigated: 74 M1 (mean BMI, 15.7kg/m2), 149 M2 (19.8 kg/m2) and 40 M3 (30.2 kg/m2). With microdose, inter- and intra-observer agreement was >0.90 for lengths whatever the morphotype, 0.75–0.90 (M1) and >0.90 (M2, M3) for valgus/varus and flexion/hyperextension deviations. Dose reduction reached a factor of 8.5 and 5.4 for the delivered and absorbed dose respectively.ConclusionsMicrodose could be used for LLA measurements in children and permits a significant dose reduction.Key points• Lower limb lengths of children can be evaluated with microdose biplanar radiography. • Valgus/varus deviations also can be evaluated with microdose biplanar radiography. • Microdose biplanar radiography significantly reduces delivered and absorbed dose in children.