Session 10: Pediatrics

17. November
09:30 - 11:00
Lokale: Vingsal 3
Chair: Marie Fridberg and Julie L. Erichsen

71. Stryde - the Danish Experience
Jan Duedal Rölfing ¹, Søren Kold ², Tobias Nygaard ³, Mindaugas Mikuzis ², Michael Brix 4 , Christian Faergemann 4, Martin Gottliebsen ¹, Michael Davidsen ¹, Juozas Petruskevicius ¹, Ulrik Kähler Olesen ³
¹ Orthopaedic Reconstruction and Children’s Orthopaedics, Aarhus University Hospital ² Department of Orthopaedics, Interdisciplinary Orthopaedics, Aalborg University Hospital ³ Department of Orthopaedics, Limb Lengthening and Bone Reconstruction Unit, Rigshospitalet 4 Department of Orthopaedics, Odense University Hospital

Background: Observing serious adverse events during treatment with the Precice Stryde bone lengthening nail (NuVasive, San Diego, CA, USA), we conducted a nationwide cross- sectional study.
Aim: To report the prevalence of adverse events from all 30 lengthened bone segments of the 27 patients treated in Denmark.
Materials and Methods: Radiographs of all bone segments were evaluated regarding radiographic changes in February 2021. We determined the number of bone segments with late onset of pain and/or radiographically confirmed osteolysis, periosteal reaction, or cortical hypertrophy in the junctional area of the nail.
Results: In 30 bone segments of 27 patients we observed radiographic changes in 21/30 segments of 20/27 patients, i.e., 19/30 osteolysis, 12/30 periosteal reaction (most often multi-layered), and 12/30 cortical hypertrophy in the area of the junction between the telescoping nail parts. Late onset of pain was a prominent feature in 8 patients. This is likely to be a prodrome to the bony changes. Discoloration (potential corrosion) at the nail interface was observed in multiple removed nails. 15/30 nails were still at risk of developing complications, i.e., were not yet removed.
Interpretation / Conclusion: All Stryde nails should be monitored at regular intervals until removal. Onset of pain at late stages of limb lengthening, i.e., consolidation of the regenerate, should warrant immediate radiographic examination regarding osteolysis, periosteal reaction, and cortical hypertrophy, which may be associated with discoloration (potential corrosion) of the nail. We recommend removal of Stryde implants as early as possible after consolidation of the regenerate.

72. A novel plate concept for rotational guided growth of the femur – An experimental porcine pilot study
Ahmed Abood ¹, Ahmed Halloum ¹, Søren Kold ¹, Marie Arildsen ¹, Ole Rahbek ¹, Jan Duedal Rölfing ²
¹ Department of Orthopaedics, Aalborg University Hospital ² Department of Orthopaedics, Aarhus University Hospital

Background: The use of guided growth to correct rotational lower limb deformities in children has been increasingly investigated. Alternative use of eight-plates and cable connected cannulated screws suggest the possibility of applying guided growth to correct rotational deformities. Still, there is no commercially available device for this purpose. We have developed a novel plate concept for rotational guided growth, which has proven effective in a cadaverous model, however large animal studies are lacking.
Aim: To proof the concept of the novel plate by rotating porcine femora through guided growth.
Materials and Methods: Six female porcines (n = 6) with a mean weight of 43 kg (38 - 47) were included in a paired design. The 3D printed titanium plates were inserted at baseline on the medial and lateral aspect of the left distal femoral physis. Each plate was attached using two 4.5 mm titanium screws. The animals were housed for 12 weeks before undergoing MRI, radiographs, and euthanasia. Change in femoral version and length between the right femur and left femur was determined on MRI. Clinical torsion was assessed using standardized photographs with the animal placed supine on a levelled table.
Results: The surgery was well tolerated by all animals, and they were ambulatory on the first post-operative day. A torsional difference was created in all operated femora. Mean change in femoral version was 12.5 degrees (9 - 16). Mean length of the operated femur was 2.9 mm (0 - 7) shorter than the non-operated. Mean clinical change in rotation was 10.3 degrees (7 - 14).
Interpretation / Conclusion: The plates were able to rotate all operated femora as intended. However, a decrease in axial growth due to the rotational guided growth cannot be ruled out. We did not assess possible changes in joint morphology. More comprehensive large animal studies investigating the precision of rotational potential of the plates in addition to detailed growth analyses including alignment in the coronal and sagittal plane are planned.

73. Midwives can measure the pubo-femoral distance reliably in ultrasound screening for developmental dysplasia of the pediatric hip.
Hans-Christen Husum, Michel Bach Hellfritszch, Mads Henriksen, Natallia Lapitskaya, Bjarne Møller-Madsen, Rikke Damkjær Maimburg, Ole Rahbek
Interdisciplinary Orthopaedics, Aalborg University Hospital; Department of Radiology, Aarhus University Hospital; Department of Children's Orthopaedics, Aarhus University Hospital; Danish Paediatric Orthopaedic Research; Department of Gynaecology and Obstetrics, Aarhus University Hospital

Background: Ultrasound screening for developmental dysplasia of the hip (DDH) is conventionally based on the Graf ultrasound technique which necessitates an experienced ultrasound user to be interpreted correctly. The pubo-femoral distance (PFD) has been proposed as a highly sensitive ultrasound screening tool for DDH, with low variability.
Aim: The aim of this study was to examine if midwives undergoing minimal training, could reliably perform pediatric hip ultrasound and measure PFD and to evaluate the learning curve of the midwives.
Materials and Methods: We recruited eight midwives with no prior experience in hip ultrasound for training in PFD measurements. They participated in a two-hour theoretical seminar on DDH screening and the PFD measurement. All midwives performed two rounds of independent blinded measurements on 15 static ultrasound images seven days apart and participated in four supervised live scanning sessions over two weeks. The midwives were compared to a group of three experienced musculoskeletal radiologists. Reliability and agreement were evaluated using interrater correlation coefficients (ICC) and Bland Altman plots. Linear regression was used to quantify the learning curve of the midwives as a group with absolute difference between midwife and radiologist as a function of number of scans.
Results: There was near complete intra- and interrater agreement (ICC > 0.89) on static ultrasound images across both rounds of rating and across both groups of raters. The midwives scanned a mean of 29 hips (range 24-35). Mean difference between midwife and supervising radiologists was 0.36mm 95% CI (0.12-0.61) for the first session which decreased to 0.2mm 95% CI (0.04-0.37) in the final session. ICC for PFD measurements between radiologist and midwives increased from 0.59 95% CI (0.37;0.75) to 0.78 95% CI (0.66;0.86) across sessions. The mean absolute difference between midwife and radiologist PFD measurements decreased by 0.1mm (95% CI 0.02-0.17) for every ten scans the midwives gained in experience (p=0.008).
Interpretation / Conclusion: Midwives reliably perform PFD measurements of pediatric hips, with minimal training, and with clinically insignificant differences compared to experienced musculoskeletal radiologists.

74. Preparing an automatic pin site infection detection tool with machine learning for home-based surveillance
Marie Fridberg ¹ , Sowmya Annadatha ², Qirui Hin ², Tobias Jensen ², Jianan Liu ², Søren Kold ², Søren Rahbek ², Ming Shen ²
1. Interdisciplinary Orthopaedics, Aalborg University Hospital, Denmark 2. Department of Electronic Systems, Aalborg University,Denmark

Background: To detect early signs of pin site infection infrared thermography has been suggested to provide quantitative information of clinical signs of pin site infection.
Aim: Our vision is to invent a pin site infection thermographic surveillance tool for patients at home. A preliminary step to this goal, is to automate the process of locating the pin and detecting the pin sites in thermographic images efficiently, exactly, and reliably for extracting the pin site temperatures.
Materials and Methods: Images (digital conventional and thermographic) were obtained in a controlled clinical setting and in an uncontrolled home setting. The total number of images of pin-sites used for developing the machine learning algorithm (images of pin sites) before augmentation was n=1708. The images was augmented, in to totally n=10.409. Randomly divided into a training set (n=8325), a validation set (n=1040) and a test set (n=1044) of images. The Pin Detection Model (PDM) was developed as follows: A You Only Look Once (YOLOv5) based object detection model with a Complete Detection Intersection over Union (CDIoU) was pre-trained by the hospital dataset and fine tuned by the home dataset through transfer learning. The performance was compared with other conventional models (FCOS and YOLOv4) for deep and transition learning to improve performance and precision. Maximum Temperature Extraction (MTE) Based on Region of Interest (ROI) for all pin sites was generated
Results: An automatic tool that can identify and annotate pin sites on digital images using bounding boxes was established. An obstacle was shifting, solved by calibration and image registration with a transformation matrix that converted every pixel on the digital images to a coordinate system of the thermographic image. The PDM algorithm was built on YOLOv5 with CDIoU and has a precision of 0.976 and it offers the pin site detection in 1.8 milliseconds. The PDM algorithm enabled MTE at an automatically detected ROI on the skin surface.
Interpretation / Conclusion: These results enable automatic pin site annotation on thermography with a precision of 0.976 in 1.8 milliseconds. This work, paves the way for future research on infection assessment using thermography.

75. Reliability of thermography in a clinical setting to detect skin temperatures at pin sites. A test-retest study
Marie Fridberg¹, Malene Engesgaard Christensen², Mathias Sørensen², Bente Madsen², Ole Rahbek¹ , Søren Kold¹
Interdisciplinary Orthopaedics, Aalborg University Hospital, Denmark; Department of Health Science and Technology, Aalborg University, Denmark.

Background: Thermography has been suggested to objectify clinical signs of pin site infection by measuring skin surface temperatures.
Aim: The aim was to test the reliability of thermography by investigating reproducibility in a test retest setup and the intra- and inter-rater reliability using two different temperature extraction methods (TEM).
Materials and Methods: Thermography was obtained of 216 pin sites in a test-retest setup using a FLIR T540 infrared camera. Session A (n=216) and B (n=216) were conducted in a standardized realistic clinical setting with 30 min. in between. The test-retest setup was similar according to photographer, patient, position, acclimatization, pins and environmental conditions. Minor variations in angle (random) and distance (40-60cm) to the pin site reflected the realistic random variations introduced by the photographer. All images (n=432) were analyzed using two different TEM in FLIR tools software: The 3-point method and the MaxROI method. Intra-rater reliability: 20 pins were analyzed twice by the same rater with one week in between. Inter-rater: 20 pins were analyzed by 3 raters blinded. ICC was calculated using a two-way mixed effects model with absolute agreement and 95% confidence intervals.
Results: Test -retest reliability of the 216 pin sites: 3-point (ICC=0.9, CI 0.88-0.93) and MaxROI method (ICC=0.91CI 0.88-0.93). The intra-rater reliability test of the two different TEM of 20 pin sites: 3-point (ICC=0.65 CI 0.30-0.84) and MaxROI method (ICC=0.91CI 0.78-0.96). The inter-rater reliability test performed by using three different raters extracting temperatures of 20 pin sites: 3-point (ICC=0.86 CI 0.76-0.92) and MaxROI method (ICC=1,00 (0.996) CI 0.99- 0.99).
Interpretation / Conclusion: Thermographic imaging used to measure skin temperatures at pin sites using a FLIR T540 infrared camera was found reproducible in a realistic clinical setting. We found an excellent test-retest reliability for both TEM despite minor variations in distance and angle. The MaxROI had the best intra-and inter-rater reliability.

76. Pubo femoral distances in hip ultrasound do not vary between lateral and supine examination positions in newborns.
Hans-Christen Husum, Christian Klitt Jensen, Mads Henriksen, Michel Bach Hellfritszch, Bjarne Møller-Madsen, Ole Rahbek
Interdisciplinary Orthopaedics, Aalborg University Hospital; Department of Radiology, Aarhus University Hospital; Department of Children's Orthopaedics, Aarhus University Hospital; Danish Paediatric Orthopaedic Research

Background: Ultrasound screening for developmental dysplasia of the hip (DDH) is conventionally based upon the method developed by Graf. In 2013 the pubo-femoral distance (PFD) was proposed as a new ultrasound screening measurement, defined as the minimally measurable distance between the medial aspect of the femoral head and the pubic bone with a PFD above 6.0 mm considered pathological. No consensus exists on the positioning of the child when performing the PFD examination.
Aim: Our aim was to examine the agreement of the PFD when measured with the child in the lateral versus supine position.
Materials and Methods: We included a consecutive series of children referred for hip ultrasound suspect of DDH during a period of two months. The PFD measurement was obtained for each child for both hips in the lateral position, afterwards the child was placed in the supine position and the PFD measurement was repeated on both sides. Ultrasound examinations were performed by two experienced pediatric musculoskeletal radiologists Mean PFD values for lateral and supine positioning were compared using Student’s paired t-test and agreement was analyzed using Bland Altman plot.
Results: We included 30 children (15 boys), mean age at examination was 34 days (range 13-83). Mean PFD in lateral position was 3.5 mm 95%CI (3.2; 3.7) and mean PFD in supine position was 3.6 95%CI (3.4 ; 3.9). Mean difference in PFD between examination positions was 0.16 mm 95% CI(-0.01 ;0.31) p=0.04. Inspection of the Bland Altman plot did not reveal a systematic difference in PFD between examination positions with increasing average PFD value.
Interpretation / Conclusion: Shifting from lateral to supine examination positions during hip ultrasound had no clinically significant impact on PFD measurements. These findings underline the versatility of the PFD measurement as a screening tool for DDH.

77. Complications of Orthopedic Treatment in Patients Diagnosed with X-linked Hypophosphatemic Rickets.
Søren Kold, Carl Paludan, Kristoffer Thomsen, Ole Rahbek
Department of Orthopaedics, Aalborg University Hospital

Background: X-linked Hypophosphatemic Rickets (XLHR) in children with a Rickets Severity Score = 2 can now be treated with the new fibroblast growth factor 23 (FGF23) antibody drug which prevents bone deformities and increases gait endurance. This study illustrates the extend and complications in the traditional orthopedic treatment in XLHR patients. The impact of surgery and severity of complications in this patient population has not been systematically assessed before. These data are needed to justify the very expensive antibody treatment
Aim: This study reviews systematically the complications of orthopedic treatment in XLHR patients
Materials and Methods: The search strategy resulted in 215 studies in which data were collected from 19 eligible studies and complications were categorized.
Results: XLHR patients without FGF23 antibody treatment undergo multiple surgeries. 168 complications were reported in 172 patient. One complication occurred in average per surgical procedure for XLHR in the published literature. The 168 reported complications were categorized as follows: Type 1 (n=79): Complications with minimal intervention required and treatment goal still achieved, Type II (n=41): Complications with substantial change in treatment plan and treatment goal still achieved, Type IIIA (n=23): Complications with failure to achieve treatment goal and no new pathology or permanent sequelae, Type IIIB (n=25): Complications with failure to achieve treatment goal and/or new pathology or permanent sequelae
Interpretation / Conclusion: In average one complication occurred per surgery and the severity of complications was remarkable. The treatment goal was not achieved in 28 % of surgeries whereof half of these resulted in permanent sequalae or new pathology. Complications were possibly underreported in current literature and complications of surgery in XLHR may therefore be underestimated. Our findings support the use of FGF23 antibody for treatment of the skeletal changes in XLHR instead of surgery as the reported side effects of antibody treatment is negligible compared to the impact of surgeries and related complications

78. The incidence of physeal fractures in the lower limb and the frequency of premature physeal closure, limb length discrepancy, and angular deformity: A cohort study of 236 physeal fractures.
David Alexander Lukas Wang Cant, Christian Færgemann
Section for Pediatric Orthopaedics, Department for Orthopaedic Surgery and Traumatology, Odense University Hospital.

Background: Pediatric fractures is a common injury among children and adolescents. Physeal fractures constitute a particular concern because of the risk of accompanying growth disturbances.
Aim: The aim of this study was to estimate incidence rates (IR) of physeal fractures in the lower limb and the frequency of premature physeal closure (PPC) leading to limb length discrepancy (LLD) and angular deformity (AD).
Materials and Methods: This retrospective cohort evaluated 236 children between 2013-2020 treated for a physeal fracture in either tibia, distal femur, or distal fibula. All medical records and radiographs/CT-scans were reviewed to obtain information regarding type of physeal fracture and the development of growth disturbances. Furthermore, we investigated relevant predictive risk factors.
Results: The total incidence rate of physeal fractures was 36.4 (CI:30.3-39.3) per 100.000 person-years, with 1.2 (CI:0.50-23.1) of distal femur, 5.7 (CI:3.1-7.8) of proximal tibia, 14.1 (CI:11.4-17.2) of distal tibia, and 13.6 (CI:11.0-16.7) of distal fibula. The overall frequency of growth disturbance was 9.7%. Within distal femur, proximal tibia, distal tibia, and distal fibula the frequency of growth disturbance was 37.5%, 15.4%, 13.5%, and 1.1%, respectively. The highest frequency of growth disturbances was in Salter-Harris type II and IV fractures (60.9 % and 34.9%). We found a significant higher risk of developing growth disturbances if the patient was treated operatively (p<0.001), sustained the fracture from a high-energy injury (p=0.02), or if the initial displacement was = 3 mm (p=0.01).
Interpretation / Conclusion: Despite a relatively low incidence of physeal fractures, we found that a recognizable part eventually develops growth disturbance, particularly children presenting with certain risk factors. We accentuate the importance of consistent and uniform growth evaluations after sustaining a physeal fracture.

79. Surgical procedures in infants with early diagnoses of developmental dysplasia of the hip. A prospective 4-year follow-up study.
Ingebrigt Grimstad Holstad , Christian Færgemann
Section for Pediatric Orthopaedics, Department of Orthopaedics and Traumatology, Odense University Hospital, Odense, Denmark

Background: To detect unstable dysplastic hips early, neonatology specialists routinely screen all new- borns in Denmark. Infants with detectable risk factors or clinical signs of dysplasia are referred to a combined pediatric orthopaedic and radiologic examination. A previous study has shown that 17% of all infants referred for this combined examination meet the diagnostic criteria of dysplasia. Four per cent have unstable hips that need treatment. Dysplastic hips may normalize spontaneously without any intervention due to the natural growth. However, some infants need one or more surgical intervention to achieve stable and non-dysplastic hips.
Aim: To determine the proportion of infants with early dysplasia of the hips undergoing surgical procedures and to determine the type and number of surgical procedures.
Materials and Methods: A prospective and consecutive study of all infants aged 0-6 months diagnosed with dysplasia of the hips in the combined pediatric orthopaedic and radiologic examination in the Region of Southern Denmark 2013-2017. From medical records, we obtained information about all surgical procedures in the hips including open or closed reductions, arthrographies, tenotomies, and pelvic osteotomies before the age of 4 years.
Results: Overall, 281 infants with hip dysplasia were included. The median age at first examination was 48 days. In 254 (90%) of the infants, the hips resolved spontaneously, and 27 (10%) needed one or more surgical interventions. Overall, the 27 infants had 47 surgical interventions as 12 infants had more than one intervention. One infants had five surgical interventions. The most frequent surgical procedures were closed reduction and arthrography with or without adductor tenotomy (58 %) and pelvic osteotomy (27%). Among infants with surgical interventions, 23 (8.2%) had unstable hips, and four (1.4 %) had stable hips. All four infants with stable hips had an arthrography and none required a pelvic osteotomy.
Interpretation / Conclusion: This study supports the propensity for spontaneous normalization of early dysplasia of the hips in infants. Only a small proportion of the infants needed surgical interventions to achieve stable and non-dysplastic hips.

80. The proportion of hip dysplasia in infants referred for combined pediatric orthopedic and radiologic examination in Region of Southern Denmark 2013-2019
Simon Norlén , Christian Færgemann
Section for Pediatric Orthopaedics, Department of Orthopaedics and Traumatology, Odense University Hospital.

Background: To detect developmental hip dysplasia (DDH) early, all newborns in Denmark are examined postnatally by a pediatrician and by a primary care physician at 5 weeks and 5 months of age. Suspect findings are referred to a combined pediatric orthopedic examination and ultrasonography. This combined examination is resource demanding, and studies have found variating effects of the screening. Previous studies have described variating proportions of DDH among infants referred for the combined examination. Furthermore, only few studies have examined which causes most commonly lead to referral and the association between different causes of referral and DDH.
Aim: To determine the proportions of infants with DDH and hip dislocation in infants referred for a combined pediatric orthopedic and radiologic assessment, and to describe the association between DDH and different reasons of referral.
Materials and Methods: A prospective study of all infants aged 0-6 months referred for a combined pediatric orthopedic and radiologic examination of the hips at Odense University Hospital or Kolding Hospital 2013-2019. We calculated the overall proportion of DDH and hip dislocations and the proportions stratified by different reasons of referral. We considered an acetabular index > 30° on radiographs or Graf Type 2b or worse on ultrasonographies diagnostic of DDH.
Results: Of the 1,989 infants included, 334 (17%) were diagnosed with DDH and 94 (4.7%) had hip dislocations. The proportions of infants with DDH among infants with a single reason of referral were 36% for breech position, 25% for familial disposition, 14% for hip click, 8% for asymmetry, and 3% for twins. The proportions of infants with unstable hip(s) were 14% for familial disposition, 12% for breech position, 3% for hip click, 3% for twins, and 1% for asymmetry.
Interpretation / Conclusion: The study demonstrates that a considerable proportion of infants referred for the combined examination have DDH and that some reasons of referral are clinically more important. The study showed that in infants with hip click and asymmetry, a considerable proportion had DDH. We recommend that infants with hip click or asymmetry should be referred for a the pediatric orthopedic and radiologic examination.