Publications by authors named "Won Joon Yoo"

125 Publications

Effect of Leg Length Discrepancy on Lateral Center-edge Angle Measurement.

J Pediatr Orthop 2022 Mar;42(3):e295-e300

Division of Paediatric Orthopaedics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Jongno-gu, Seoul, Republic of Korea.

Background: In patients with leg length discrepancy (LLD) and consequent pelvic obliquity, either the longitudinal axis of the pelvis or a line perpendicular to the ground may be used as the longitudinal reference line for measuring the lateral center-edge angle (LCEA). We aimed to (1) systematically inspect which longitudinal reference line has been used for measuring the LCEA in previous studies; (2) evaluate the frequency of change in the radiographical classification of acetabular overcoverage or undercoverage per the longitudinal reference line; and (3) validate the trigonometric method, predicting the change in the LCEA according to the LLD.

Methods: Studies investigating the LCEA published between January 1976 and July 2019 in the MEDLINE database were categorized according to the longitudinal reference line used. Further, in a retrospective analysis of 238 patients surgically treated for LLD, the LCEA was first measured on standing pelvic radiographs using the longitudinal axis of the pelvis (pLCEA) and measured again using a line perpendicular to the ground (gLCEA). Femoral head coverage was categorized as undercoverage, normal, or overcoverage based on the pLCEA and gLCEA. The theoretically calculated difference between the pLCEA and gLCEA (dLCEA) as determined using a trigonometric method was compared with the dLCEA measured on radiographs.

Results: Of 229 previous studies, 188 did not specify the longitudinal reference line. The number of patients who were diagnosed with acetabular overcoverage using the pLCEA and gLCEA was one and fourteen, respectively (P<0.001). The number of patients who were diagnosed with acetabular undercoverage using the pLCEA and gLCEA was one and zero, respectively (P=1.000). There was no difference (P=0.433) between the theoretically calculated (9±5 degrees) and measured (9±5 degrees) dLCEAs.

Conclusions: The definition of the longitudinal reference line should be clarified when measuring the LCEA. The trigonometric method can accurately predict the change in the LCEA according to LLD in concentric hips without proximal femoral and pelvic deformities.

Level Of Evidence: Level IV-diagnostic study.
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http://dx.doi.org/10.1097/BPO.0000000000002034DOI Listing
March 2022

Intra-articular acetabular osteochondroma in patients with multiple hereditary exostoses.

J Pediatr Orthop B 2022 Jan;31(1):e90-e94

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Republic of Korea.

We report three additional cases of intra-articular acetabular osteochondroma in multiple hereditary exostoses patients in order to raise the awareness of this rare location, to prompt early diagnosis, and to present various treatment options according to the patient's condition. A 2.5-year-old boy presenting with an out-toeing gait had a large acetabular osteochondroma causing lateral displacement of the femoral head and acetabular dysplasia. Mass excision through hip subluxation via anterior approach and concomitant Dega osteotomy resulted in a congruent, well-developed, and well-covered hip joint at 11-year follow-up. A 10-year-old boy showing a pedunculated osteochondroma arising from the triradiate cartilage was successfully treated by arthroscopic excision. Normal development of the hip joint was observed at skeletal maturity. A 6-year-old boy presented with a painless limp. Acetabular osteochondroma could be confirmed by computed tomography scan, which was excised through hip subluxation by anterior approach. Persistent coxa valga and femoral head uncovering were addressed by femoral varization osteotomy at 9 years of age. A high index of suspicion is required to detect a lesion at this rare location. Various procedures may be considered according to the pathoanatomy. Acetabular dysplasia, coxa valga, and femoroacetabular impingement by femur neck mass, if associated, should be addressed in due time.
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http://dx.doi.org/10.1097/BPB.0000000000000889DOI Listing
January 2022

Prospective study of epigenetic alterations responsible for isolated hemihyperplasia/hemihypoplasia and their association with leg length discrepancy.

Orphanet J Rare Dis 2021 10 9;16(1):418. Epub 2021 Oct 9.

Division of Clinical Genetics, Department of Paediatrics, Seoul National University Children's Hospital, Seoul National University College of Medicine, 101 Daehak-ro Jongno-gu, Seoul, 03080, Republic of Korea.

Background: Hemihyperplasia and hemihypoplasia result in leg length discrepancy (LLD) by causing skeletal asymmetry. Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) are opposite growth-affecting disorders caused by opposite epigenetic alterations at the same chromosomal locus, 11p15, to induce hemihyperplasia and hemihypoplasia, respectively. Because of their somatic mosaicism, BWS and SRS show a wide spectrum of clinical phenotypes. We evaluated the underlying epigenetic alterations and potential epigenotype-phenotype correlations, focusing on LLD, in a group of individuals with isolated hemihyperplasia/hemihypoplasia.

Results: We prospectively collected paired blood-tissue samples from 30 patients with isolated hemihyperplasia/hemihypoplasia who underwent surgery for LLD. Methylation-specific multiplex-ligation-dependent probe amplification assay (MS-MLPA) and bisulfite pyrosequencing for differentially methylated regions 1 and 2 (DMR1 and DMR2) on chromosome 11p15 were performed using the patient samples. Samples from patients showing no abnormalities in MS-MLPA or bisulfite pyrosequencing were analyzed by single nucleotide polymorphism (SNP) microarray and CDKN1C Sanger sequencing. We introduced a metric named as the methylation difference, defined as the difference in DNA methylation levels between DMR1 and DMR2. The correlation between the methylation difference and the predicted LLD at skeletal maturity, calculated using a multiplier method, was evaluated. Predicted LLD was standardized for stature. Ten patients (33%) showed epigenetic alterations in MS-MLPA and bisulfite pyrosequencing. Of these, six and four patients had epigenetic alterations related to BWS and SRS, respectively. The clinical diagnosis of hemihyperplasia/hemihypoplasia was not compatible with the epigenetic alterations in four of these ten patients. No patients showed abnormalities in SNP array or their CDKN1C sequences. The standardized predicted LLD was moderately correlated with the methylation difference using fat tissue (r = 0.53; p = 0.002) and skin tissue (r = 0.50; p = 0.005) in all patients.

Conclusions: Isolated hemihyperplasia and hemihypoplasia can occur as a spectrum of BWS and SRS. Although the accurate differentiation between isolated hemihyperplasia and isolated hemihypoplasia is important in tumor surveillance planning, it is often difficult to clinically differentiate these two diseases without epigenetic tests. Epigenetic tests may play a role in the prediction of LLD, which would aid in treatment planning.
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http://dx.doi.org/10.1186/s13023-021-02042-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8501601PMC
October 2021

Acute correction of proximal tibial coronal plane deformity in small children using a small monolateral external fixator with or without cross-pinning.

J Child Orthop 2021 Jun;15(3):255-260

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Korea.

Purpose: Surgical correction of proximal tibia deformity in small children can be challenging. We present the surgical technique and outcome of proximal tibia osteotomy fixed with small monolateral external fixator in this patient group.

Methods: A total of 17 cases in eight patients younger than nine years of age were study subjects. A proximal tibia osteotomy was fixed with a small monolateral external fixator with or without cross-pinning. Outcome was evaluated by changes of radiographic parameters such as medial proximal tibia angle (MPTA), metaphyseal diaphyseal angle (MDA) and clinical findings of complications, time interval until weight bearing and fixator removal time.

Results: MPTA improved from a preoperative mean of 73° (sd 4°; 66° to 78°) to an immediate postoperative mean of 90° (sd 3°; 85° to 96°) in varus tibiae, and from 104° (sd 1°; 103° to 105°) to 89° (sd 1°; 88° to 89°) in valgus tibiae. In all, 15 of the 17 cases (88.3 %) achieved postoperative MPTA within the normal range (85° to 90°). MDA improved from a preoperative mean of 19° (sd 5°; 11° to 24°) to an immediate postoperative mean of 0° (sd 4°; -6° to 7°) in varus tibiae, and from -25° (sd 2°; -22° to -24°) to 2° (SD 1°; 1° to 3°) in valgus tibiae. Full weight bearing was possible at mean 1.7 months (0.5 to 3.0). Mean follow-up period was 6.5 years (sd 5.4; 1.0 to 16.0). No complications developed during the follow-up.

Conclusion: Proximal tibia osteotomy fixed with small monolateral external fixator provides accurate, safe and efficient correction in the management of coronal plane angular deformity in small children.

Level Of Evidence: Level IV.
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http://dx.doi.org/10.1302/1863-2548.15.200187DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8223093PMC
June 2021

Patterns of femoral neck fracture and its treatment methods in patients with osteogenesis imperfecta.

J Pediatr Orthop B 2022 Mar;31(2):e114-e121

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital.

Femoral neck fracture (FNF) is not common in osteogenesis imperfecta patients but may result in serious complications if not properly treated in due time. We present three types of FNF in osteogenesis imperfecta and their characteristics, treatment methods and outcomes. Cases of FNF followed for more than 2 years were selected from the osteogenesis imperfecta database. Medical records and radiographs were reviewed to obtain demographic information and to determine ambulatory status, mode of injury, location of the fracture line, presence of preexisting implants, treatment methods and complications. Outcomes were evaluated according to the radiographic results and ambulatory function. The study investigated 15 FNFs in 10 patients including 1 Sillence type I, 1 type III and 8 type IV. They were either community or household ambulators. The mean age at fracture was 11.7 years. The fractures were followed for an average of 6.3 years. Six fractures were attributed to accidental injuries and nine without noticeable trauma. The fracture pattern was categorized into undisplaced (n = 3), angulated-stable (n = 7) or displaced-unstable (n = 5) types. Five fractures were fixed in-situ using screws or Kirschner wires. Other five fractures were treated by closed reduction and screw fixation and the remaining five fractures were managed by femoral valgus osteotomy. Bony union was achieved, and prefracture ambulatory status was restored in all cases. A high index of suspicion is required in the diagnosis of undisplaced or angulated-stable fractures. Treatment is usually challenging, but a judicious approach considering the fracture pattern and patient characteristics result in successful outcomes. The angulated-stable pattern of fracture is unique in osteogenesis imperfecta patients and requires special attention.
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http://dx.doi.org/10.1097/BPB.0000000000000887DOI Listing
March 2022

MRI risk factors for development of avascular necrosis after closed reduction of developmental dysplasia of the hip: Predictive value of contrast-enhanced MRI.

PLoS One 2021 18;16(3):e0248701. Epub 2021 Mar 18.

Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, Korea.

Purpose: The purpose of this study was to identify imaging risk factors on contrast-enhanced hip MRI after closed reduction of developmental dysplasia of the hip (DDH) that could predict future development of avascular necrosis (AVN) of the femoral head.

Materials And Methods: Fifty-eight infants (F: M = 53: 5, aged 3-18 months) who underwent immediate postoperative contrast-enhanced hip MRI after closed reduction of DDH were included in this study. Quality of reduction (concentric vs eccentric reduction with or without obstacles), abduction angle of the hip, presence of ossific nucleus, and pattern of contrast enhancement of the femoral head were retrospectively evaluated on MRI. Interobserver agreement of contrast enhancement pattern on MRI were evaluated by two radiologists. Development of AVN was determined through radiographic findings at 1 year after reduction.

Results: AVN of the femoral head developed in 13 (22%) of 58 patients. Excessive abduction of the hip joint (OR 4.65, [95% CI 1.20, 18.06] and global decreased enhancement of the femoral head (OR 71.66, [95% CI 10.54, 487.31]) exhibited statistically significant differences between the AVN and non-AVN groups (P < 0.05). Eccentric reduction (P = 0.320) did not show statistically significant difference between two groups and invisible ossific nucleus (P = 0.05) showed borderline significance. Multi-variable logistic regression indicated that global decreased enhancement of the femoral head was a significant risk factor of AVN (OR 27.92, 95% CI [4.17, 350.18]) (P = 0.0031). Interobserver agreement of contrast enhancement pattern analysis and diagnosis of AVN were good (0.66, 95% CI [0.52, 0.80]).

Conclusion: Contrast-enhanced hip MRI provides accurate anatomical assessment of the hip after closed reduction of DDH. Global decreased enhancement of the femoral head could be used as a good predictor for future development of AVN after closed reduction of DDH.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0248701PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7971487PMC
October 2021

Pseudo-Protrusio Acetabular Deformity in Osteogenesis Imperfecta Patients.

J Pediatr Orthop 2021 Mar;41(3):e285-e290

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul.

Background: Osteogenesis imperfecta (OI) can develop a protrusio acetabuli deformity. However, the authors observed a pseudo-protrusio-type acetabular deformity (PPAD) on 3-dimensional computed tomography (3D-CT). Hence, we systematically reviewed 3D-CT and pelvis radiographs of OI patients and report the incidence and patterns of acetabular deformity in OI patients and the associated radiographic signs.

Methods: The study included 590 hips of 295 OI patients, who were older than 5 years, and did not have a pelvic fracture. The incidence of a deformed acetabulum (center-edge angle >40 degrees) and its correlation with disease severity were investigated. In 40 hips for which 3D-CT was available, 3-dimensional morphology of the acetabular deformity was analyzed to delineate PPAD. On plain radiographs, PPAD-related signs were determined, focusing on the contour of ilioischial line, iliopectineal line, acetabular line, and their relationship. These radiographic signs were also evaluated in the remaining hips with deformed acetabula that did not have 3D-CT.

Results: One hundred twenty-three hips of 590 hips (21%) showed deformed acetabula. The incidence of deformed acetabula was significantly associated with disease severity (P<0.001). Three-dimensional analysis showed that 10 hips had protrusio acetabuli, whereas 17 had PPAD, which showed that the hemipelvis was crumpled, the acetabular roof was rotated upwardly and medially, and the hip center migrated superiorly, uncovering the anterior femoral head. Among the PPAD-related signs, superomedial bulging of the iliopectineal line was the most predictive radiographic sign (73% sensitivity and 100% specificity). This sign was also observed in almost one third of deformed acetabula of those investigated only with plain radiographs.

Conclusions: This study showed that acetabular deformity is common in OI patients and is associated with disease severity. A substantial number of hips showed PPAD, which may not cause femoroacetabular impingement but result in anterior uncovering of the hip joint. Superomedial bulging of the iliopectineal line suggests this pattern of acetabular deformity.

Level Of Evidence: Lever IV-prognostic studies.
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http://dx.doi.org/10.1097/BPO.0000000000001739DOI Listing
March 2021

Management of Osteogenesis Imperfecta: A Multidisciplinary Comprehensive Approach.

Clin Orthop Surg 2020 Dec 18;12(4):417-429. Epub 2020 Nov 18.

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.

Osteogenesis imperfecta (OI) is characterized by recurring fractures and limb and spine deformities. With the advent of medical therapeutics and the discovery of causative genes, as well as the introduction of a newly devised intramedullary rod, the general condition and ambulatory function of patients diagnosed with OI have been improved over the past decades. This review covers recent developments in research and management of OI.
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http://dx.doi.org/10.4055/cios20060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7683189PMC
December 2020

Effective and Rapid Microbial Identification in Pediatric Osteoarticular Infections Using Blood Culture Bottles.

J Bone Joint Surg Am 2020 Oct;102(20):1792-1798

Divisions of Pediatric Orthopaedics (C.H.S., T.-J.C., I.H.C., and W.J.Y.), and Pediatrics (E.H.C.), Seoul National University Children's Hospital, Seoul, Republic of Korea.

Background: The detection and identification of pathogenic microorganisms are essential for the treatment of osteoarticular infection. However, obtaining a sufficient amount of specimen from pediatric patients is often difficult. Herein, we aimed to demonstrate the effectiveness of the blood culture bottle (BCB) system in pediatric osteoarticular infections. We hypothesized that our BCB culture method is superior to the conventional swab and tissue culture methods in terms of required specimen size, incubation time, and microbial identification rate.

Methods: We analyzed the prospectively collected data of pediatric patients who underwent surgical treatment for osteoarticular infections between August 2016 and October 2019. Four needles were dipped in the infected fluid or tissue during the surgical procedure as soon as the infected area was exposed and were used to inoculate 2 aerobic pediatric BCBs and 2 anaerobic general BCBs. We also collected 2 conventional swab samples and 2 tissue samples from the identical area. The microbial identification rate and the time required for identification were compared between BCB, swab, and tissue cultures.

Results: Forty patients constituted the study group; 13 patients had osteomyelitis, 17 patients had septic arthritis, and 10 patients had both. Of these 40 patients, the microbial identification rate was higher with BCB cultures (27 [68%]) than with swab cultures (18 [45%]; p = 0.004) or tissue cultures (15 [38%]; p < 0.001). Nine samples (9 patients [23%]) were only positive in the BCB culture. Positive microbial growth was not detected with conventional culture methods when microorganisms did not grow on the BCB culture. Compared with swab culture (4.3 ± 1.1 days; p < 0.001) or tissue culture (4.4 ± 1.1 days; p < 0.001), the BCB culture reduced the time required for microbial identification (3.5 ± 0.9 days).

Conclusions: In pediatric osteoarticular infections, the BCB culture system improved the microbial identification rate, reduced the time to identification, and permitted a smaller-volume specimen, compared with traditional culture systems.

Level Of Evidence: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.20.00219DOI Listing
October 2020

Detailed analysis of phenotypes and genotypes in megalencephaly-capillary malformation-polymicrogyria syndrome caused by somatic mosaicism of PIK3CA mutations.

Orphanet J Rare Dis 2020 08 10;15(1):205. Epub 2020 Aug 10.

Department of Pediatrics, Seoul National University Children's Hospital, Seoul National University College of Medicine, Jongnogu Daehakro 101, Seoul, 03080, Republic of Korea.

Background: Megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP) belongs to a group of conditions called the PIK3CA-related overgrowth spectrum (PROS). The varying phenotypes and low frequencies of each somatic mosaic variant make confirmative diagnosis difficult. We present 12 patients who were diagnosed clinically and genetically with MCAP. Genomic DNA was extracted mainly from the skin of affected lesions, also from peripheral blood leukocytes and buccal epithelial cells, and target panel sequencing using high-depth next-generation sequencing technology was performed.

Results: Macrocephaly was present in 11/12 patients (92%). All patients had normal body asymmetry. Cutaneous vascular malformation was found in 10/12 patients (83%). Megalencephaly or hemimegalencephaly was noted in all 11 patients who underwent brain magnetic resonance imaging. Arnold-Chiari type I malformation was also seen in 10 patients. Every patient was identified as having pathogenic or likely pathogenic variants of the PIK3CA gene. The variant allele frequency (VAF) ranged from 6.3 to 35.3%, however, there was no direct correlation between VAF and the severity of associated anomalies. c.2740G > A (p.Gly914Arg) was most commonly found, in four patients (33%). No malignancies developed during follow-up periods.

Conclusions: This is the first and largest cohort of molecularly diagnosed patients with MCAP in Korea. Targeted therapy with a PI3K-specific inhibitor, alpelisib, has shown successful outcomes in patients with PROS in a pilot clinical study, so early diagnosis for genetic counseling and timely introduction of emerging treatments might be achieved in the future through optimal genetic testing.
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http://dx.doi.org/10.1186/s13023-020-01480-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7418424PMC
August 2020

Which Acetabular Landmarks are the Most Useful for Measuring the Acetabular Index and Center-edge Angle in Developmental Dysplasia of the Hip? A Comparison of Two Methods.

Clin Orthop Relat Res 2020 09;478(9):2120-2131

C. H. Shin, E. Yang, C. Lim, W. J. Yoo, I. H. Choi, T-J. Cho, Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Republic of Korea.

Background: The acetabular index and center-edge angle are widely used radiographic parameters. However, the exact landmarks for measuring these parameters are not clearly defined. Although their measurement is straightforward when the lateral osseous margin of the acetabular roof coincides with the lateral end of the acetabular sourcil, where these two landmarks disagree, recommendations have differed about which landmark should be used. Using a radiographic parameter with high reliability for predicting residual hip dysplasia helps avoid unnecessary treatment.

Questions/purposes: We aimed to (1) compare two landmarks (the lateral osseous margin of the acetabular roof and the lateral end of the acetabular sourcil) for measuring the acetabular index and center-edge angle with respect to intraobserver and interobserver reliability and the predictability of residual hip dysplasia in patients with developmental dysplasia of the hip (DDH) and (2) evaluate longitudinal change in the acetabular edge's shape after closed reduction with the patient under general anesthesia.

Methods: Between February 1985 and July 2006, we performed closed reduction with the patient under general anesthesia as well as cast immobilization in 116 patients with DDH. To be included in this study, a patient had to have dislocated-type DDH. We excluded patients with a hip dislocation associated with neuromuscular disease, arthrogryposis, or congenital anomalies of other organs or systems (n = 9); hips that underwent osteotomy within 1 year since closed reduction (n = 8); hips that underwent open reduction because of re-dislocation after closed reduction (n = 4); and hips with Type III or IV osteonecrosis according to Bucholz-Ogden's classification (n = 4). Ninety-one patients were eligible. We excluded 19% (17 of 91) of the patients, who were lost to follow-up before they were 8 years old, leaving 81% (74 of 91 patients) with full preoperative and most-recent data. Ninety-seven percent (72 patients) were girls and 3% (two patients) were boys. The mean ± standard deviation age was 14.0 months ± 6.4 months (range 3-40 months) at the time of closed reduction and 12.1 years ± 2.3 years (range 8.0-16.0 years) at the time of the latest follow-up examination, the duration of which averaged 11 years ± 2.2 years (range 6.5-15.4 years). To investigate whether longitudinal change in the acetabular edge's shape differed among hips with DDH, contralateral hips, and control hips, we identified control participants after searching our hospital's database for patients with a diagnosis of congenital idiopathic hemihypertrophy from October 2000 to November 2006 who had AP hip radiographs taken at 3 years old and then at older than 8 years. From 29 patients who met these criteria, we randomly excluded two male patients to match for sex because girls were predominant in the DDH group. We excluded another female patient from the control group because of a hip radiograph that revealed unacceptable rotation. Eventually, 26 patients were assigned to the control group. Control patients consisted of 24 girls (92%) and two boys (8%). The demographic characteristics of control patients was not different from those of 67 patients with unilateral DDH, except for laterality (left-side involvement: 64% [43 of 67] in the DDH group versus 38% [10 of 26] in the control group; odds ratio 1.7 [95% confidence interval, 1.0-2.8]; p = 0.035). The acetabular index and center-edge angle at 3 years old were measured using the lateral osseous margin of the acetabular roof (AIB and CEAB) and the lateral end of the acetabular sourcil (AIS and CEAS). The treatment outcome was classified as satisfactory (Severin Grade I or II) or unsatisfactory (Grade III or IV). The intraclass correlation coefficient (ICC) was used to compare the intraobserver and interobserver reliability of each method. We compared the predictability of residual hip dysplasia of each method at 3 years old as a proxy using the area under the receiver operating characteristic (AUC) curve. To evaluate longitudinal change in the acetabular edge's shape, we compared the proportion of hips showing coincidence of the two landmarks between 3 years old and the latest follow-up examination. To investigate whether the longitudinal change in the acetabular edge's shape differs among hips with DDH, contralateral hips, and control hips, we compared the proportion of coincidence among the three groups at both timepoints.

Results: Intraobserver and interobserver reliabilities were higher for the CEAB (ICC 0.96; 95% CI, 0.94-0.98 and ICC 0.88; 95% CI, 0.81-0.92, respectively) than for the CEAS (ICC 0.81; 95% CI, 0.70-0.88 and ICC 0.69; 95% CI, 0.55-0.79, respectively). The AIB (AUC 0.88; 95% CI, 0.80-0.96) and CEAB (AUC 0.841; 95% CI, 0.748-0.933) predicted residual hip dysplasia better than the AIS (AUC 0.776; 95% CI, 0.67-0.88) and CEAS (AUC 0.72; 95% CI, 0.59-0.84) (p = 0.03 and p = 0.01, respectively). The proportion of hips showing coincidence of the two landmarks increased from 3 years old to the latest follow-up examination in hips with DDH (37% [25 of 67] to 81% [54 of 67]; OR = 8.8 [95% CI, 3.1-33.9]; p < 0.001), contralateral hips (42% [28 of 67] to 85% [57 of 67]; OR = 16.5 [95% CI, 4.2-141.9]; p < 0.001), and control hips (38% [10 of 26] to 88% [23 of 26]; OR = 14 [95% CI, 2.1-592.0]; p = 0.001). The proportion of coincidence in hips with DDH was not different from that in the contralateral hips and control hips at both timepoints.

Conclusions: Measuring the acetabular index and center-edge angle at 3 years old using the lateral osseous margin of the acetabular roof has higher reliability for predicting residual hip dysplasia than that using the lateral end of the acetabular sourcil in patients with DDH treated with closed reduction. Measuring the acetabular index and center-edge angle at an early age using the lateral end of the sourcil may lead to overdiagnosis of residual hip dysplasia and unnecessary treatment.

Level Of Evidence: Level III, diagnostic study.
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http://dx.doi.org/10.1097/CORR.0000000000001289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431232PMC
September 2020

Inter-segmental foot kinematics during gait in elderly females according to the severity of hallux valgus.

J Orthop Res 2020 11 20;38(11):2409-2418. Epub 2020 Mar 20.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, Korea.

The objective of this study was to find the effect of hallux valgus (HV) deformity on the inter-segmental motion of the foot using an MFM with a 15-marker set (DuPont Foot Model, DuFM) in comparison with age and sex controlled healthy adults. Fifty-eight female symptomatic HV patients and 50 female asymptomatic older female volunteers were included in this study. According to the radiographic hallux valgus angle (HVA), the study population was divided into severe HV (SHV, HVA ≥ 40°, n = 25), moderate HV (MHV, 20° ≤ HVA < 40°, n = 47), and control (CON, n = 36). MHV group was divided into symptomatic MHV group (S-MHV, n = 33) and asymptomatic MHV group (A-MHV, n = 14) according to the symptoms associated with HV. For temporal parameters, gait speed and stride length were diminished according to the severity of HV deformity. Sagittal range of motion of hallux and hindfoot decreased significantly in SHV group. Loss of push-off during the preswing phase was observed and forefoot adduction motion during terminal stance was decreased in SHV group. In a subgroup analysis of MHV, asymptomatic HV minimally affects gait and inter-segmental motion during gait. HV deformity affects gait parameters and inter-segmental motion of the foot during gait in proportion to the severity of the deformity. However, the effect of MHV itself on foot kinematics might be limited while pain or arthritic change of the joint might cause changes in gait in patients with symptomatic HV.
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http://dx.doi.org/10.1002/jor.24657DOI Listing
November 2020

Functional Outcomes of Hip Arthroscopy for Pediatric and Adolescent Hip Disorders.

Clin Orthop Surg 2020 Mar 13;12(1):94-99. Epub 2020 Feb 13.

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Korea.

Background: There is a paucity of literature on the use of hip arthroscopy for pathologic conditions in skeletally immature patients. Thus, the indications and safety of the procedure are still unclear. The purpose of this study was to investigate the safety and functional outcomes of hip arthroscopy for pediatric and adolescent hip disorders. We further attempted to characterize arthroscopic findings in each disease.

Methods: We retrospectively reviewed 32 children and adolescents with hip disorders who underwent 34 hip arthroscopic procedures at a tertiary care children's hospital from January 2010 to December 2016. We evaluated functional limitations and improvement after operation by using the modified Harris hip score (HHS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), subjective pain assessment with a visual analog scale (VAS), and range of hip motion as well as the complications of hip arthroscopy. Arthroscopic findings in each disease were recorded.

Results: Hip arthroscopy was performed for Legg-Calvé-Perthes disease (n = 6), developmental dysplasia of the hip (n = 6), slipped capital femoral epiphysis (n = 5), idiopathic femoroacetabular impingement (n = 6), sequelae of septic arthritis of the hip (n = 3), hereditary multiple exostosis (n = 2), synovial giant cell tumor (n = 3), idiopathic chondrolysis (n = 2), and posttraumatic osteonecrosis of the femoral head (n = 1). Overall, there was a significant improvement in the modified HHS, WOMAC, VAS, and range of hip motion. Symptom improvement was not observed for more than 18 months in four patients who had dysplastic acetabulum with a labral tear (n = 2) or a recurrent femoral head bump (n = 2). There were no complications except transient perineal numbness in five patients.

Conclusions: Our short-term follow-up evaluation shows that hip arthroscopy for pediatric and adolescent hip disorder is a less invasive and safe procedure. It appears to be effective in improving functional impairment caused by femoroacetabular impingement between the deformed femoral head and acetabulum or intra-articular focal problems in pediatric and adolescent hip disorders.
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http://dx.doi.org/10.4055/cios.2020.12.1.94DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7031430PMC
March 2020

Diagnosis and Management of Hip Dislocation in Patients with Kabuki Syndrome.

Clin Orthop Surg 2019 Dec 12;11(4):474-481. Epub 2019 Nov 12.

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Korea.

Background: Kabuki syndrome is a rare genetic disorder characterized by distinct dysmorphic facial features, growth deficiency, intellectual disabilities, unusual dermatoglyphic patterns, and skeletal abnormalities. The incidence of hip dislocation in Kabuki syndrome ranges from 18% to 62%. We reviewed the outcomes of management of hip dislocations in patients with Kabuki syndrome with special attention to the diagnostic processes for hip dislocation and Kabuki syndrome.

Methods: Among 30 patients with mutation-confirmed Kabuki syndrome, we selected six patients who had hip dislocations and reviewed their medical records and plain radiographs. The modes of presentation and diagnostic processes for both hip dislocations and Kabuki syndrome were investigated. The management and treatment outcomes of hip dislocations in patients with Kabuki syndrome were evaluated.

Results: The average age of patients at the time of diagnosis of hip dislocation was 7.7 months (range, 1 week to 22 months). None of the patients were diagnosed as having Kabuki syndrome at that time. Two patients were treated with a Pavlik harness; one, with closed reduction; two, with open reduction and later pelvic and/or femoral osteotomies; and one, with open reduction combined with pelvic osteotomy. The patients were followed up for 5.8 years on average (range, 2.0 to 10.5 years). The radiologic outcome was graded as Severin IA or IB for three patients who were older than 6 years at the latest follow-up (mean age, 9.9 years; range, 7.8 to 12.4 years). In the remaining three patients younger than 6 years (mean age, 3.8 years; range, 2.7 to 5.3 years), the lateral center edge angle was more than 15°. The clinical diagnosis of Kabuki syndrome was made during follow-up after hip dislocation treatment and confirmed by mutational analysis at a mean age of 4.7 years. The mean interval between the diagnosis of hip dislocation and Kabuki syndrome was 4.0 years.

Conclusions: The management of hip dislocation by conservative or surgical method showed successful results. Awareness of Kabuki syndrome could lead to an early diagnosis of this rare disease in patients with hip dislocation and allow for early detection of other underlying conditions and multidisciplinary management.
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http://dx.doi.org/10.4055/cios.2019.11.4.474DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6867925PMC
December 2019

Overgrowth of the lower limb after treatment of developmental dysplasia of the hip: incidence and risk factors in 101 children with a mean follow-up of 15 years.

Acta Orthop 2020 04 12;91(2):197-202. Epub 2019 Nov 12.

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul.

Background and purpose - There are few studies on overgrowth of the affected limb after treatment of developmental dysplasia of the hip (DDH). We investigated the incidence of overgrowth and its risk factors in DDH patients.Patients and methods - 101 patients were included in this study. Overgrowth was defined by 2 criteria: when the height of the femoral head of the affected side was higher than that of the contralateral side by more than 10 mm, or by more than 15 mm. The potential risk factors of distinct overgrowth were retrospectively examined using multivariable analysis.Results - When overgrowth was defined as femoral head height difference (FHHD) > 10 mm, its incidence was 44%, and only femoral osteotomy was identified as a significant risk factor with a relative risk (RR) of 1.6 (95% confidence interval [CI] 1.0-2.5). When overgrowth was defined as FHHD > 15 mm, its incidence was 23%, and femoral osteotomy was identified as the only significant risk factor with an RR of 2.3 (CI 1.2-4.5). Overgrowth developed more frequently in patients who underwent femoral osteotomy at the age of 2 to 4 years (87%) than in the others (46%) (p = 0.04).Interpretation - Overgrowth of the affected limb is common in DDH patients. Patients who underwent femoral osteotomy, especially at the age of 2 to 4 years, may require careful follow-up because of the substantial risk for overgrowth.
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http://dx.doi.org/10.1080/17453674.2019.1688485DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7144334PMC
April 2020

Physeal and Subphyseal Distraction Osteogenesis in Atrophic-type Congenital Pseudarthrosis of the Tibia: Efficacy and Safety.

J Pediatr Orthop 2019 Sep;39(8):422-428

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul.

Purpose: To examine the efficacy, safety, and clinical outcomes of distraction osteogenesis through the physis (PDO) or through subphyseal osteotomy (SPDO) in patients with atrophic-type congenital pseudarthrosis of tibia with proximal tibial dysplasia.

Methods: To validate the efficacy and safety of PDO and SPDO, radiographic and clinical parameters were compared between 5 patients who underwent proximal tibial metaphyseal or metadiaphyseal lengthening as a control (group 1) and 7 patients who underwent PDO or SPDO (group 2). Postoperative complication was also compared between the groups.

Results: A significant difference in terms of healing index (group 1, 83.3±24.7 d/cm; group 2, 35.0±11.1 d/cm; P=0.001) and percentage increase (11.0%±3.7% vs. 23.1%±10.5%, P=0.034) was observed between the 2 groups. According to the Paley classification, group 1 included 1 "problems" case and 3 "obstacles" cases, whereas group 2 included 2 "problems" cases and 1 "obstacles" case. According to the Lascombes classification, group 1 included 2 grade IIIb cases and 3 grade IV cases, whereas group 2 included 6 grade I cases and 1 grade IIa case. Severe complications were significantly higher in group 1 compared with the group 2 (P=0.007).

Conclusions: This study demonstrated that PDO or SPDO can be effectively and safely performed for tibial lengthening in atrophic-type congenital pseudarthrosis of tibia patients with proximal tibial dysplasia.

Level Of Evidence: Level III.
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http://dx.doi.org/10.1097/BPO.0000000000000979DOI Listing
September 2019

In Vivo Response of Growth Plate to Biodegradable Mg-Ca-Zn Alloys Depending on the Surface Modification.

Int J Mol Sci 2019 Aug 1;20(15). Epub 2019 Aug 1.

Department of Orthopaedic Surgery, Chung-Ang University Medical Center, 102 Heukseok-ro, Dongjak-gu, Seoul 06973, Korea.

Because Mg-Ca-Zn alloys are biodegradable and obviate secondary implant removal, they are especially beneficial for pediatric patients. We examined the degradation performance of Mg-Ca-Zn alloys depending on the surface modification and investigated the in vivo effects on the growth plate in a skeletally immature rabbit model. Either plasma electrolyte oxidation (PEO)-coated ( = 18) or non-coated ( = 18) Mg-Ca-Zn alloy was inserted at the distal femoral physis. We measured the degradation performance and femoral segment lengths using micro-CT. In addition, we analyzed the histomorphometric and histopathologic characteristics of the growth plate. Although there were no acute, chronic inflammatory reactions in either group, they differed significantly in the tissue reactions to their degradation performance and physeal responses. Compared to non-coated alloys, PEO-coated alloys degraded significantly slowly with diminished hydrogen gas formation. Depending on the degradation rate, large bone bridge formation and premature physeal arrest occurred primarily in the non-coated group, whereas only a small-sized bone bridge formed in the PEO-coated group. This difference ultimately led to significant shortening of the femoral segment in the non-coated group. This study suggests that optimal degradation could be achieved with PEO-coated Mg-Ca-Zn alloys, making them promising and safe biodegradable materials with no growth plate damage.
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http://dx.doi.org/10.3390/ijms20153761DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6695941PMC
August 2019

Osteitis Following Immunization with Bacille Calmette-Guérin (BCG) in Korea.

J Korean Med Sci 2019 Jan 26;34(1):e3. Epub 2018 Dec 26.

Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.

Background: Bacille Calmette-Guérin (BCG) osteitis, a rare complication of BCG vaccination, has not been well investigated in Korea. This study aimed to evaluate the clinical characteristics of BCG osteitis during the recent 10 years in Korea.

Methods: Children diagnosed with BCG osteitis at the Seoul National University Children's Hospital from January 2007 to March 2018 were included. BCG was confirmed by multiplex polymerase chain reaction (PCR) in the affected bone. BCG immunization status and clinical information were reviewed retrospectively.

Results: Twenty-one patients were diagnosed with BCG osteitis and their median symptom onset from BCG vaccination was 13.8 months (range, 6.0-32.5). Sixteen children (76.2%) received Tokyo-172 vaccine by percutaneous multiple puncture method, while four (19.0%) and one (4.8%) received intradermal Tokyo-172 and Danish strain, respectively. Common presenting symptoms were swelling (76.2%), limited movement of the affected site (63.2%), and pain (61.9%) while fever was only accompanied in 19.0%. Femur (33.3%) and the tarsal bones (23.8%) were the most frequently involved sites; and demarcated osteolytic lesions (63.1%) and cortical breakages (42.1%) were observed on plain radiographs. Surgical drainage was performed in 90.5%, and 33.3% of them required repeated surgical interventions due to persistent symptoms. Antituberculosis medications were administered for a median duration of 12 months (range, 12-31). Most patients recovered without evident sequelae.

Conclusion: Highly suspecting BCG osteitis based on clinical manifestations is important for prompt management. A comprehensive national surveillance system is needed to understand the exact incidence of serious adverse reactions following BCG vaccination and establish safe vaccination policy in Korea.
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http://dx.doi.org/10.3346/jkms.2019.34.e3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6318445PMC
January 2019

Repeatability of a Multi-segment Foot Model with a 15-Marker Set in Normal Children.

Clin Orthop Surg 2018 Dec 21;10(4):484-490. Epub 2018 Nov 21.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, Korea.

Background: The use of three-dimensional multi-segment foot models (3D MFMs) is increasing since they have superior ability to illustrate the effect of foot and ankle pathologies on intersegmental motion of the foot compared to single-segment foot model gait analysis. However, validation of the repeatability of the 3D MFMs is important for their clinical use. Although many MFMs have been validated in normal adults, research on MFM repeatability in children is lacking. The purpose of this study is to validate the intrasession, intersession, and interrater repeatability of an MFM with a 15-marker set (DuPont foot model) in healthy children.

Methods: The study included 20 feet of 20 healthy children (10 boys and 10 girls). We divided the participants into two groups of 10 each. One group was tested by the same operator in each test (intersession analysis), while the other group was tested by a different operator in each test (interrater analysis). The multiple correlation coefficient (CMC) and intraclass correlation coefficient (ICC) were calculated to assess repeatability. The difference between the two sessions of each group was assessed at each time point of gait cycle.

Results: The intrasession CMC and ICC values of all parameters showed excellent or very good repeatability. The intersession CMC of many parameters showed good or better repeatability. Interrater CMC and ICC values were generally lower for all parameters than intrasession and intersession. The mean gaps of all parameters were generally similar to those of the previous study.

Conclusions: We demonstrated that 3D MFM using a 15-marker set had high intrasession, intersession, and interrater repeatability in the assessment of foot motion in healthy children but recommend some caution in interpreting the hindfoot parameters.
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http://dx.doi.org/10.4055/cios.2018.10.4.484DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6250958PMC
December 2018

Dual Interlocking Telescopic Rod Provides Effective Tibial Stabilization in Children With Osteogenesis Imperfecta.

Clin Orthop Relat Res 2018 11;476(11):2238-2246

C. H. Shin, W. J. Yoo, I. H. Choi, T.-J. Cho, Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Republic of Korea D. J. Lee, Department of Orthopaedic Surgery, Kangwon National University Hospital, Chuncheon, Republic of Korea.

Background: Interlocking telescopic rods for the management of osteogenesis imperfecta (OI)-related long bone fractures are a modification of the Sheffield rod. An interlocking pin anchors the obturator at the distal epiphysis, which spares the distal joint, while a T-piece anchors the sleeve at the proximal epiphysis. However, these devices are associated with some problems, including failure to elongate and difficulty with removal. A dual interlocking telescopic rod (D-ITR), in which the sleeve and the obturator are anchored with interlocking pins, was developed to address these problems.

Questions/purposes: In this study, we compared the D-ITR with an older version of a single interlocking telescopic rod (S-ITR) based on (1) surgery-free survival and rod survival; (2) cessation of rod elongation and elongated length of the rod; and (3) risk of refracture and complications related to the interlocking telescopic system.

Methods: This article compares the D-ITR with the S-ITR using a historically controlled, single-surgeon, retrospective design comparing two implants for the management of fractures in children with OI. Before August 2007, we exclusively used the S-ITR (n = 17 patients, 29 tibiae); from July 2008 until October 2014, we exclusively used the D-ITR (n = 17 patients, 26 tibiae). During the 1-year transition period, we performed five of these procedures (two S-ITR in two patients and three D-ITR in three patients), and implant use was based on availability with our preference being the D-ITR during that time when it was available. The general indications for use of both devices were the same: patients with OI and a tibial fracture who were older than 3 to 4 years of age and whose tibial canals were wide enough to accept an intramedullary rod. Younger patients were treated other ways (generally without surgery) and those with narrower canals with thinner, nonelongating rods or Kirschner wires, as indicated. All patients in both groups were available for followup at a minimum of 2 years (mean ± SD, 9.6 ± 3.0 years in the S-ITR group and 5.3 ± 2.1 years in the D-ITR group) except for one patient in the D-ITR group who died > 1 year after the procedure resulting from reasons unrelated to it. For the between-group comparison, we used only the followup data collected up to the ninth postoperative year in the S-ITR group. The truncated followup period of the S-ITR group was a mean of 5.0 ± 1.6 years. The mean age in the S-ITR group was 7 years (range, 3-12 years) and it was 8 years (range, 3-14 years) in the D-ITR group. There were nine boys and 10 girls in each group. Two orthopaedic surgeons other than the operating surgeon performed chart review to address our three research purposes. Survival analyses were performed using the Kaplan-Meier method. The overall pooled risk of refracture and major complications potentially associated with the interlocking telescopic rod system was compared between the groups.

Results: With the numbers available, there were no differences between the D-ITR and the S-ITR in terms of mean surgery-free survival time (5.7 [95% confidence interval {CI}, 4.5-6.9] versus 5.1 [95% CI, 4.1-6.1]; years; p = 0.653) or mean rod survival time (7.4 [95% CI, 6.4-8.4] versus 6.0 [95% CI, 5.1-6.9] years; p = 0.120). With the numbers available, cessation of elongation (4% in the D-ITR group versus 19% in the S-ITR group; p = 0.112) and elongated length (45.3 ± 24.3 mm in the D-ITR group versus 44.2 ± 22.3 mm in the S-ITR group; p = 0.855) also did not differ between the groups. The pooled proportions of refracture or complications after the index surgery were higher in the S-ITR group (25 tibias [81%]) than in the D-ITR group (15 tibias [54%]; p = 0.049). Eight tibias in the S-ITR group had proximal migration of the sleeve compared with no patients in the D-ITR group (p = 0.005).

Conclusions: In patients with OI, the modified D-ITR provides effective tibial stabilization with similar or better results than the S-ITR design. Anchoring the sleeve at the proximal epiphysis with an interlocking pin provides better anchorage and allows easier removal.

Level Of Evidence: Level III, therapeutic study.
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http://dx.doi.org/10.1097/CORR.0000000000000429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6260010PMC
November 2018

Inter-segment foot motion in girls using a three-dimensional multi-segment foot model.

Gait Posture 2018 06 6;63:184-188. Epub 2018 May 6.

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Republic of Korea. Electronic address:

Background: Several multi-segment foot models (MFMs) have been introduced for in vivo analyses of dynamic foot kinematics. However, the normal gait patterns of healthy children and adolescents remain uncharacterized. We sought to determine normal foot kinematics according to age in clinically normal female children and adolescents using a Foot 3D model.

Methods: Fifty-eight girls (age 7-17 years) with normal function and without radiographic abnormalities were tested. Three representative strides from five separate trials were analyzed. Kinematic data of foot segment motion were tracked and evaluated using an MFM with a 15-marker set (Foot 3D model). As controls, 50 symptom-free female adults (20-35 years old) were analyzed.

Results: In the hindfoot kinematic analysis, plantar flexion motion in the pre-swing phase was significantly greater in girls aged 11 years or older than in girls aged <11 years, thereby resulting in a larger sagittal range of motion. Coronal plane hindfoot motion exhibited pronation, whereas transverse plane hindfoot motion exhibited increased internal rotation in girls aged <11 years. Hallux valgus angles increased significantly in girls aged 11 years or older. The foot progression angle showed mildly increased internal rotation in the loading response phase and the swing phase in girls aged <11 years old.

Conclusion: The patterns of inter-segment foot motion in girls aged 11 years or older showed low-arch kinematic characteristics, whereas those in girls aged 11 years or older were more similar to the patterns in young adult women.
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http://dx.doi.org/10.1016/j.gaitpost.2018.05.007DOI Listing
June 2018

Clinical and radiological outcomes of arthroscopically assisted cannulated screw fixation for tibial eminence fracture in children and adolescents.

BMC Musculoskelet Disord 2018 02 6;19(1):41. Epub 2018 Feb 6.

Department of Orthopaedic Surgery, Seoul National University College of Medicine, 101 Daehak-ro Jongno-gu, Seoul, 03080, Republic of Korea.

Background: The purpose of this study was to determine the efficacy and complications of arthroscopically assisted reduction and fixation with cannulated screws for tibial eminence fracture in skeletally immature patients.

Methods: This was a retrospective case series study. Forty-eight patients who were skeletally immature at the time of tibial eminence fracture were treated in a tertiary children's hospital between May 2004 and August 2015. Twenty-one patients were excluded due to non-operative treatment (n = 10), other surgical treatments (n = 9), multiple fracture (n = 1), and follow-up < 1 year (n = 1). Twenty-seven knees of 27 patients were analyzed. Avulsed fragment was reduced arthroscopically. One to three cannulated screws (4.0 mm or 5.0 mm in diameter) were used for fixation. Passive knee motion was started in 3-4 weeks. Clinical outcomes were evaluated by Lysholm score, instability of the knee, and complications. Radiological outcomes including nonunion and malunion of the avulsed fragment and physeal growth disturbance were evaluated.

Results: Mean age at the time of surgery was 10.1 years (range, 6.2 to 13.8 years). Patients were followed up for a mean of 3.9 years (range, 1.0 to 7.6 years). Fracture types included type III (n = 13), type II (n = 12), and type IV (n = 2) according to Zaricznyj modification of Meyers and McKeever classification. Meniscus was entrapped in five patients. Six patients showed concomitant meniscal tear. Mean Lysholm score at the latest follow-up was 95 (range, 78 to 100). Joint instability was not observed in any patient except one (instability of 5-10 mm). All patients showed full range of knee motion except one (10 degrees of flexion contracture). Screw head impingement against intercondylar notch of the femur was observed in two patients during screw removal procedure. Five knees showed prominent tibial eminence without symptoms. The injured lower limb was longer than the contralateral normal side by a mean of 6.2 mm (range, - 4 to 18 mm).

Conclusions: Arthroscopically assisted reduction and fixation with cannulated screws is an effective and safe surgical option for treating tibial eminence fracture with few complications.
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http://dx.doi.org/10.1186/s12891-018-1960-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5801812PMC
February 2018

Percutaneous medial hemi-epiphysiodesis using a transphyseal screw for caput valgum associated with developmental dysplasia of the hip.

BMC Musculoskelet Disord 2017 Nov 14;18(1):451. Epub 2017 Nov 14.

Department of Orthopaedic Surgery, Seoul National University College of Medicine, Seoul, Republic of Korea.

Background: The purpose of this study was to evaluate the radiologic outcome of percutaneous medial hemi-epiphysiodesis using a transphyseal screw for the management of caput valgum associated with developmental dysplasia of the hip (DDH).

Methods: Eighteen hips (18 patients) having caput valgum treated with screw hemi-epiphysiodesis were followed for more than 2 years, and were included in this study. The mean age at the time of the index operation was 8.3 years (range, 4.3 to 10.7 years) and age at the latest follow-up was 12.2 years (range, 9.4 to 16.4 years). The screw in 5 hips was changed into a longer one at postoperative 21.8 months (range, 14 to 29 months) because the proximal femur outgrew the screw. The screws in 11 hips were removed at the mean age of 10.9 years (range, 8.0 to 14.5 years). We retrospectively analyzed the change in various radiologic parameters over time.

Results: The mean Hilgenreiner-epiphyseal angle (HEA) of the operated side was 5.1 ± 11.3° preoperatively, and increased to 20.6 ± 11.3° at the latest follow-up (p = 0.001). The mean difference of the HEA between the operated and contralateral sides was 16.9 ± 15.1° preoperatively, which decreased to 2.4 ± 12.4° at the latest follow-up (p = 0.008). The mean articulo-trochanteric distance of the operated side, which was 3.2 ± 5.5 mm longer than that of the contralateral side preoperatively, became 5.6 ± 9.1 mm shorter at the latest follow-up (p = 0.001). The ratio of femoral neck length of the operated side to that of the contralateral side decreased over the follow-up period. Acetabular shape as measured by the Sharp angle and acetabular roof angle and femoral head coverage as measured by lateral center-edge angle did not change significantly by the index operation. The ratio of medial joint space width of the operated side to that of the contralateral side did not change significantly.

Conclusions: Screw medial hemi-epiphysiodesis can effectively correct caput valgum associated with DDH. However, this technique remains coxa brevis and does not seem to significantly affect acetabular morphology or reduce subluxation.
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http://dx.doi.org/10.1186/s12891-017-1833-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5686794PMC
November 2017

Postinfectious heterotopic ossification of the ilium involving the iliacus muscle.

J Pediatr Orthop B 2018 Sep;27(5):407-411

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Republic of Korea.

Heterotopic ossification in soft tissue or muscle is rare in the pediatric and adolescent age group. Most cases are associated with musculoskeletal injury and trauma to the central nervous system. Here, we describe an adolescent patient without a history of trauma or lesions in the central nervous system who presented with a painful limp with limited motion of the left hip. Investigations indicated unusually large heterotopic ossification extending from the inner aspect of the ilium down to the anterior part of the hip, highly likely to have developed after an unrecognized periacetabular pyomyositis primarily involving the iliacus muscle. Surgical excision was performed successfully without perioperative complications. No recurrence was detected at the final follow-up.
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http://dx.doi.org/10.1097/BPB.0000000000000477DOI Listing
September 2018

Slipped capital femoral epiphysis in children younger than 10 years old: clinical characteristics and efficacy of physeal-sparing procedures.

J Pediatr Orthop B 2018 Sep;27(5):379-386

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul.

We aimed to investigate the clinical characteristics of slipped capital femoral epiphysis (SCFE) in patients aged less than 10 years and identify the efficacy of physeal-sparing procedures in this age group. Demographic data of 18 SCFE patients aged less than 10 years were compared with those of 71 older patients to investigate the clinical characteristics. The efficacy of physeal-sparing procedures (n=5) was investigated compared with that of in-situ screw fixation (n=13). Obese children were noticeably more common among SCFE patients aged less than 10 years (P=0.034). The slip angle improved significantly more in the physeal-sparing subgroups (P=0.038) without the occurrence of further slippage. Moreover, physeal-sparing procedures allow persistent growth of the proximal femoral physis. However, most of the patients in the physeal-sparing subgroup needed additional surgeries when the proximal femoral physis outgrew the implant. Obesity may be associated more with early-onset SCFE (onset<10 years). Physeal-sparing procedures are safe and effective in preventing leg-length discrepancy and allowing the remodeling of the deformed proximal femur in this age group.
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http://dx.doi.org/10.1097/BPB.0000000000000485DOI Listing
September 2018

Orthopedic Manifestations of Type I Camurati-Engelmann Disease.

Clin Orthop Surg 2017 Mar 13;9(1):109-115. Epub 2017 Feb 13.

Division of Pediatric Orthopedics, Seoul National University Children's Hospital, Seoul, Korea.

Background: Camurati-Engelmann disease (CED) is a rare genetic skeletal disorder characterized by limb pain, muscle emaciation and weakness, and cortical thickening of the diaphysis of long bones. It is caused by mutations in the transforming growth factor beta 1 (TGFB1) (type I) or other unknown gene(s) (type II). We present 8 consecutive patients with type I CED.

Methods: We retrospectively reviewed medical records and radiographs of type I CED patients with special reference to the mode of presentation, process of diagnostic work-up, and disease course. They were 4 sporadic patients, and two pairs of mother and son.

Results: We categorized the mode of presentation into three groups. Group I had 4 patients who mainly presented with motor disturbances in young age. They drew medical attention for waddling gait, awkward ambulation or running, difficulty in going upstairs, or a positive Gower's sign at age 4 to 6 years. Subsequent development of limb pain and radiographic abnormality led to the diagnosis of CED at age 6 to 29 years. Group II had 3 patients who mainly presented with limb pain at age 15, 20, and 54 years, respectively. Radiographic evaluation and molecular genetic test led to the diagnosis of CED. The remaining 1 patient (group III) was asymptomatic until age 9 years when bony lesions at the tibiae were found incidentally. For the last 10 years, he intermittently complained of leg pain in the morning or after sports activities, which did not interfere with daily life. All the patients in group I showed a body mass index in the underweight range (< 18.4 kg/m). At the latest follow-up, 4 patients in groups I and II required medication for the limb pain.

Conclusions: CED presents with a wide range of severity. Awareness of this rare disease entity may be the key to timely correct diagnosis. This disease entity should be considered in the differential diagnosis of limb pain or motor disturbance in children to avoid unnecessary diagnostic work-up.
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http://dx.doi.org/10.4055/cios.2017.9.1.109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5334020PMC
March 2017

Femoral overgrowth in children with congenital pseudarthrosis of the Tibia.

BMC Musculoskelet Disord 2016 07 12;17:274. Epub 2016 Jul 12.

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, 101 Daehak-ro, Jongno-gu, Seoul, South Korea.

Background: Having observed a tendency towards femoral overgrowth (FO) of the affected limb in children with atrophic-type congenital pseudarthrosis of the tibia (CPT), we aimed to identify the incidence of, contributors to, and patterns of FO among such children.

Methods: We retrospectively evaluated 55 children with CPT, 22 with prepseudarthrosis and 33 with atrophic-type CPT from 1989 to 2012. FO was defined as an affected femoral segment ≥10 mm longer than the contralateral segment. We investigated FO incidences in prepseudarthrosis versus atrophic-type CPT. Sex, laterality, coexistence of neurofibromatosis type 1, development of frank pseudarthrosis, extent of tibial shortening, shortening in foot height, deformity severity, distraction osteogenesis (DO) treatment, refracture, increased femoral neck-shaft angle, tibiofemoral angle, and ankle valgus angle were investigated to identify potential contributors to FO. Patterns of FO were also determined.

Results: At initial presentation, 11 patients exhibited a mean of 13 mm (10-23) of FO. However, the nature of FO changed over time during the follow-up period (mean, 10.8 years; range, 4.3-19.3). At the last follow-up, 14 patients presented with a mean of 12 mm (10-18) of FO. With the exception of one patient, all patients with FO presented with atrophic-type CPT. Frank pseudarthrosis, DO treatment, and increased femoral neck-shaft angle were significantly associated with FO (p = 0.016, p = 0.001, and p = 0.005, respectively). Diverse patterns of FO were observed.

Conclusions: FO of the affected limb is frequently encountered in patients with atrophic-type CPT. A compensatory response to frank pseudarthrosis, DO treatment, and neurofibromatosis may play a role in the diverse patterns of FO.
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http://dx.doi.org/10.1186/s12891-016-1157-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4941009PMC
July 2016

Acetabular Remodeling and Role of Osteotomy After Closed Reduction of Developmental Dysplasia of the Hip.

J Bone Joint Surg Am 2016 Jun;98(11):952-7

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Republic of Korea

Background: The purposes of this study were to evaluate acetabular remodeling after closed reduction of developmental dysplasia of the hip (DDH) and to delineate the role of osteotomy.

Methods: Eighty-four hips with DDH treated with closed reduction and followed until the patient was 8 years of age or older were included in this study. The mean age at closed reduction was 14.0 months (range, 3 to 30 months) and that at the latest follow-up visit was 12.7 years (range, 8.0 to 24.7 years). Osteotomy was performed in 26 hips (31%) during the follow-up period, at an average age of 2.8 years (range, 2.0 to 5.8 years). The acetabular index (AI) and center-edge angle (CEA) were measured, and osteonecrosis was graded. The treatment outcome was evaluated as satisfactory (Severin grade I or II) or unsatisfactory (III or IV). We retrospectively analyzed the associations among radiographic parameters, performance of osteotomy, grade of osteonecrosis, and final outcome.

Results: A satisfactory outcome was observed in 67 (80%) of the 84 hips. An osteotomy was not performed in 30 of 34 hips with an AI of <32° and a CEA of >14° at the age of 3 years, and 28 (93%) of these 30 hips showed a satisfactory outcome. Of the 33 hips with an AI of ≥32° and a CEA of ≤14° at the age of 3 years, the 20 that had undergone an osteotomy showed a higher proportion of satisfactory outcomes than the 13 hips that had not (p = 0.01). Three of the 4 hips that showed an unsatisfactory outcome following an osteotomy had an AI of ≥34° at 1 year post-osteotomy. Grade-II, III, or IV osteonecrosis, according to the Bucholz-Ogden classification, developed in 10 of the 84 hips, and these 10 hips had a higher proportion of unsatisfactory outcomes than did those that developed no or grade-I osteonecrosis (p = 0.004).

Conclusions: Hips with DDH showing poor acetabular remodeling after closed reduction may benefit from osteotomy. The AI and CEA at the age of 3 years can serve as one of the guidelines for osteotomy. Continued surveillance for acetabular remodeling is required even after osteotomy.

Level Of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.15.00992DOI Listing
June 2016

Foot and Ankle Function at Maturity After Ilizarov Treatment for Atrophic-Type Congenital Pseudarthrosis of the Tibia: A Comprehensive Outcome Comparison with Normal Controls.

J Bone Joint Surg Am 2016 Mar;98(6):490-8

Division of Pediatric Orthopedics, Seoul National University Children's Hospital, Seoul, South Korea

Background: The purpose of this study was to evaluate clinical outcomes and the biomechanical function of the foot and ankle at skeletal maturity of patients treated for atrophic-type congenital pseudarthrosis of the tibia (CPT) compared with healthy young adult controls.

Methods: Twenty-four patients (mean age of 19.1 years) who had undergone Ilizarov treatment for unilateral atrophic-type CPT were compared with twenty-four controls (mean age of 19.6 years). All participants were evaluated using validated outcome questionnaires, radiographs, physical examination, instrumented motion analysis including a multisegmental foot model, and pedobarographic measurement.

Results: Within the CPT group, the mean score of the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale was 89.9 (range, 76 to 100), and the mean score of the Oxford Ankle Foot Questionnaire (OAFQ) was 42.8 (range, 15 to 60). Motion analysis and pedobarographic measurement showed differences in biomechanical function of the foot and ankle on the side affected by CPT: a slower walking speed due to the short stride length; decreased dorsiflexion in hallux motion; increased hindfoot pronation in the presence of forefoot supination; diminished ankle push-off power; delayed time to heel-rise; and decreased forefoot pressure relative to hindfoot pressure. However, sagittal motion of the hindfoot and forefoot on the affected side was relatively well preserved. Subgroup analysis demonstrated no significant differences in terms of clinical outcome scores and most biomechanical parameters between the tibiofibular synostosis group and the intact-fibula group.

Conclusions: Children with atrophic-type CPT can obtain satisfactory foot and ankle function at maturity after successful Ilizarov treatment. Early stabilization of the ankle mortise by fibular stabilization and preservation of ankle mobility during and after treatment is thought to be crucial to maintaining function of the ankle in patients with CPT.

Level Of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.15.00964DOI Listing
March 2016
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