Reapplication of the Pavlik Harness for Treatment of Developmental Dysplasia of the Hip After Initial Pavlik Harness Failure.

OBJECTIVE: The Pavlik harness (PH) has been widely used as the standard treatment for infants with developmental dysplasia of the hip (DDH). When the initial application of the PH fails, alternative treatments, such as closed reduction, open reduction, and reapplication of the PH will be considered. Compared with other treatments, reapplication of the PH offers certain advantages, including simplicity and reduced physical, and psychological stress, on both infants and caregivers. This study aims to investigate the effectiveness of reapplying the PH in patients with DDH. METHODS: This study included patients with DDH (complete dislocation) who were treated by reapplication of PH between 1988 and 2012. Patients who were able to follow-up for more than 5 years were included. We examined the reduction rate and several factors to identify indicators associated with successful reduction during reapplication, including age, sex, side of hip dislocation, and the presence of the Ortolani sign. At the final follow-up, hip development was assessed using the Severin classification, whereas avascular necrosis (AVN) was evaluated using the Kalamchi classification and the Salter criteria. RESULTS: A total of 56 patients (48 females and 8 males) and 57 hips were included in this study. The mean age at first and second application of PH was 4.2 months old (range: 0.12 to 6.4), and 5.8 months old (3.0 to 11.4), respectively. The reduction rate was 49% (28 out of 57 hips). Among the successfully reduced hips, the AVN rate was 3.6% (1 out of 28 hips). The Severin classification revealed 27 hips in class I and 1 hip in class III. Statistical analysis indicated a significantly higher proportion of left hip involvement in the reduction group (85% vs 41%, χ 2 test, P < 0.001). Although not statistically significant, the rate of positive Ortolani sign tended to be higher in the reduction group (61% vs 38%, χ 2 test, P = 0.06). CONCLUSION: The reapplication method demonstrated a 49% reduction rate and a low AVN rate of 3.6% in our study. It is worth considering for patients who fail the initial PH treatment, particularly in cases of left-side dislocation and a positive Ortolani sign during the initial application.

Radiologic Changes After 10 Years Postreduction in Developmental Dysplasia of the Hip Treated With Different Reduction Methods and Risk Factors for Osteoarthritis.

BACKGROUND: This study examined how radiologic indices at 10 years postreduction change over time and influence the final outcome through a comparative study of 3 reduction methods for developmental dysplasia of the hip, including the Pavlik harness, closed reduction, and open reduction (OR). METHODS: Patients treated from 1990 to 2000 for dysplasia of the hip and followed up for >20 years were included in this study. Radiologic indices at 10 years postreduction and final follow-up (average 24 years postreduction) were measured in the 3 groups. The relative joint space of <66% compared with the healthy side was defined as positive osteoarthritis (OA) at the final follow-up. The relationship between OA and factors such as age, sex, method of reduction, radiologic indices, and Severin and Kalamchi classifications at 10 years postreduction were examined. Clinical evaluation was performed using the modified Harris Hip Score; a score of ≥80 was defined as good performance at the final follow-up. RESULTS: Sixty-five patients (totaling 74 hips) were included. There were no significant differences in radiologic indices between the 10-year postreduction time and final follow-up. Excluding 9 bilateral patients, based on the relative joint space, 21% of the patients (13/56 hips), were positive for OA. Univariate analysis showed that the incidence of positive OA was significantly associated with OR and Kalamchi grade 4 at 10 years postreduction. The modified Harris Hip Score was 80 or higher in 90% of the cases at the final follow-up. CONCLUSIONS: No significant changes in hip morphology were observed at 10 years postreduction. The Kalamchi classification at 10 years postreduction and OR were significantly associated with the incidence of OA at the final follow-up. Therefore, patients who undergo OR and/or display Kalamchi grade 4 have a high risk of developing OA and would require individual instructions for their daily lives to prevent further progression of OA and longer follow-up. LEVEL OF EVIDENCE: Level Ⅲ-case-control study.

Effects of bone marrow-derived mesenchymal stem cell transplantation in piglet Legg-Calve-Perthes disease models: a pilot study.

This preliminary study investigated the efficacy and safety of bone marrow-derived mesenchymal stem cell transplantation in a piglet Legg-Calve-Perthes disease (LCPD) model. The LCPD model was induced in two Landrace piglets (6- and 7-week-old, weighing 12 and 17 kg, respectively) by ligaturing the femoral neck. In the first piglet, the natural LCPD course was observed. In the second piglet, 4 weeks after ligaturing the femoral neck, simple medium and medium containing 2.44 × 107 bone marrow-derived mesenchymal stem cells were transplanted into the right and left femoral heads after core decompression, respectively. Plain radiographs were obtained every 4 weeks, and the epiphyseal quotient was calculated by dividing the maximum epiphysis height by the maximum epiphysis diameter. The piglets were sacrificed at 14 weeks postoperatively. The femoral heads were extracted and evaluated grossly, pathologically, and by using computed tomography. The transplanted cell characteristics were evaluated using flow cytometry. Flattening of the epiphysis was observed in both femoral heads of the first piglet and only in the right hip of the second piglet. The epiphyseal quotients immediately and at 14 weeks postoperatively in the right femoral head of the second piglet were 0.40 and 0.14, respectively, while those of the left femoral head were 0.30 and 0.42, respectively. Hematoxylin and eosin staining did not reveal physeal bar or tumor cell formation. The transplanted cells were 99.2%, 65.9%, 18.2%, and 0.16% positive for CD44, CD105, CD29, and CD31, respectively. Core decompression combined with bone marrow-derived mesenchymal stem cell transplantation prevented epiphyseal collapse.

An exploratory clinical trial for concentrated autologous bone marrow aspirate transplantation in the treatment of osteonecrosis of the femoral head.

PURPOSE: This study evaluated the efficacy and safety of a novel treatment for osteonecrosis, in which concentrated autologous bone marrow aspirate transplantation (CABMAT) is followed by low-intensity pulsed ultrasound (LIPUS) stimulation for 3 months. The study was designed as a prospective, uncontrolled, open-label phase II clinical study. METHODS: This study included 16 cases of osteonecrosis of the femoral head (ONFH), including 26 hips. Patients were transplanted with concentrated bone marrow and periodically evaluated for infection and neoplasm development. Moreover, clinical and radiological examinations were conducted to confirm the treatment efficacy. RESULTS: No infections were observed during the course of this study nor tumours developed at the treatment site 24 months after transplantation. At a mean 48 (30-56) months post-transplantation, the onset or progression of collapse was noted in four hips, of which one hip underwent total hip arthroplasty. CONCLUSION: Treatment with CABMAT combined with 3-month LIPUS stimulation was safe, and further randomised clinical studies are needed to determine the efficacy and feasibility of this treatment. TRIAL REGISTRATION: UMIN Clinical Trials Registry (UMIN000020940, 9/2/2016).

Total Hip Arthroplasty After Failed Hip-Preserving Surgery with Concentrated Autologous Bone Marrow Aspirate Transplantation for Osteonecrosis of the Femoral Head: A Retrospective Study.

Purpose: Since 2003, a hip-preserving technique-concentrated autologous bone marrow aspirate transplantation (CABMAT)-has been applied to treat osteonecrosis of the femoral head (ONFH). We investigated intraoperative and postoperative outcomes of total hip arthroplasty (THA) in patients who underwent CABMAT as hip-preserving surgery for ONFH but developed secondary hip osteoarthritis after progressive femoral head collapse. Methods: A total of 456 hips in 282 patients underwent CABMAT in our hospital between April 2003 and December 2018; 108 hips required THA (THA conversion rate, 23.7%). We enrolled 60 hips (26 hips in 20 men and 34 in 26 women) with a follow-up of over 2 years. We retrospectively analyzed patient background data, time to THA, surgical procedure, postoperative complications, and clinical outcomes from medical records. Results: The disease was steroid-related, alcohol-related, and idiopathic in 48, seven, and five hips, respectively. The mean age at THA was 45.7 years, and mean conversion time was 2.7 years. Cementless THA was performed in all cases; the mean operating time and blood loss were 82.7 min and 210 g, respectively. Postoperative complications were observed in four cases; intraoperative fracture, two cases; superficial infection, one case; and dislocation, one case. The mean follow-up period was 5.7 years; no loosening or deep infections occurred. No patients required revision arthroplasty. Conclusion: We noted no complications related to CABMAT. After a minimum 2-year follow-up, the clinical outcomes were good. CABMAT was found to be an useful hip-preserving surgery, with little effect on conversion to THA, and THA outcomes were good.

Comparison Between Concentrated Autologous Bone Marrow Aspirate Transplantation as a Hip Preserving Surgery and Natural Course in Idiopathic Osteonecrosis of the Femoral Head.

Purpose The purpose is to compare the therapeutic efficacy of concentrated autologous bone marrow aspirate transplantation (CABMAT) with that of observation alone for osteonecrosis of the femoral head (ONFH). Methods This single-center study included patients with idiopathic ONFH that were either treated with CABMAT (CABMAT group) or managed through observation alone (observation group) over a >2-year follow-up period. The Japanese Investigation Committee classification was used to diagnose and classify ONFH. The collapse rates for stages 1 and 2 ONFH (i.e., pre-collapse stages) and the THA conversion rates were compared between the CABMAT and observation groups. Results The CABMAT and observation groups comprised 232 (mean follow-up: 8.2 years) and 106 (mean follow-up: 6.0 years) patients, respectively. No significant intergroup differences were noted in the stages, types, and associated factors of ONFH. The collapse rates for pre-collapse stages in the CABMAT and observation groups were 67.1% and 65.3%, respectively. For stage 1, the collapse rates were significantly lower in the observation group than in the CABMAT group (p<0.05). The overall THA conversion rates in the CABMAT and observation groups were 24.3% and 41.5%, respectively (p<0.0001). For ONFH of stages 3A and 3B (collapse stages), the THA conversion rates were significantly lower in the CABMAT group (p<0.05). Conclusion Collapse rates were significantly higher for stage 1 ONFH; for collapse stages, the THA conversion rates were significantly lower in the CABMAT group than in the observation group. Therefore, observation and CABMAT are recommended for ONFH of stage 1 and for ONFH of higher stages, respectively.

Evaluation of Anterior Coverage in Children With Developmental Dysplasia of the Hip Using Transverse Magnetic Resonance Imaging at 2 Years Is Predictive of Future Radiographic Coverage.

BACKGROUND: Although normal anterior acetabular coverage provides stability to the hip, acetabular retroversion leads to femoroacetabular impingement related to hip osteoarthritis. Previous studies have focused on acetabular version and anteroposterior coverage in children with developmental dysplasia of the hip (DDH); however, the correlation between anteroposterior coverage and acetabular development is unclear. We measured anteroposterior acetabular coverage in DDH patients using transverse magnetic resonance imaging (MRI) and subsequent bony acetabular growth, and evaluated the correlation of those findings. METHODS: We evaluated 37 DDH (dislocations) in 36 patients who underwent MRI at 2 years of age. The mean age was 2.2±0.3 years at the time of MRI (1.6±0.4 y after reduction) and 6.0±0.1 years at the time of plain radiography for the Severin classification. On MRI scans, we measured the cartilaginous center-edge angle (CCEA) and cartilaginous acetabular-head index (CAHI) in the coronal plane and the anterior and posterior cartilaginous center-edge angles (AC-CEA and PC-CEA, respectively) in the transverse plane. Severin I or II was defined as a good outcome and III or IV as a poor outcome. RESULTS: In the evaluations conducted at 2 years of age, the mean CCEA, CAHI, AC-CEA, and PC-CEA were 14±9 degrees, 66%±10%, 39±8 degrees, and 77±7 degrees, respectively; the CEA at 6 years of age was 13±7 degrees. Twelve and 25 hips were classified in the good and poor outcome groups, respectively. Although CCEA, CAHI, and AC-CEA were significantly associated with the outcome in a single regression analysis ( P <0.05), only AC-CEA was significant in the multiple regression analysis with a stepwise selection method ( P =0.018). The cutoff AC-CEA value for a good outcome was 38 degrees (sensitivity, 67%; specificity, 68%) using a receiver operating characteristic curve. CONCLUSIONS: Among MRI findings for acetabular cartilaginous morphology, AC-CEA was strongly associated with the outcome. Anteroposterior coverage was correlated with bony acetabular growth in childhood, and anterior coverage was particularly important for subsequent acetabular growth. LEVEL OF EVIDENCE: Level IV-case series.

Influence of commuting methods on low back pain and musculoskeletal function of the lower limbs in elementary school children: A cross-sectional study.

BACKGROUND: Lower limb flexibility is known to be decreased in those living in mountainous areas, and musculoskeletal growth is often influenced by lifestyle factors. The purpose of this study was to determine the relationship between the means of transportation to school and lower limb musculoskeletal function and low back pain. METHODS: During routine medical examinations conducted in two cities in a prefecture in 2016, a questionnaire was administered. The parents of 15,259 students who attended elementary school answered questions evaluating the following parameters: (1) anteflexion limit in the standing posture, (2) crouching failure, (3) one leg standing failure, (4) low back pain during lumbar extension, (5) lower limb alignment abnormalities, and (6) flat foot. Students were divided into a walking commuting group (13,569 students) and a vehicle commuting group (1690 students), and findings were compared between the two groups using chi-square tests. RESULTS: In the walking and vehicle commuting groups, anteflexion limit in the standing posture was present in 23.3% and 26.1% of students, respectively (p = 0.013). Crouching failure was present in 4.6% and 7.3% of students (p < 0.001); one leg standing failure in 5.3% and 8.5% of students (p < 0.001); low back pain in 5.0% and 7.1% of students (p < 0.001); positive leg alignment abnormalities in 7.3% and 8.0% of students (p = 0.260); and flat foot in 7.4% and 8.7% of students (p = 0.067), respectively. Significant differences were observed in all four of the failure measures. No significant differences were observed in the two methods evaluating morphological abnormalities. CONCLUSIONS: The decreased walking duration and increased sitting duration associated with vehicle commuting had little effect on lower limb morphology but could induce lower limb dysfunction and low-back pain in children. Thus, supplemental walking should be instated for children who commute by car.

The relationship between gluteus medius and minimus muscle volumes and hip development in developmental dysplasia of the hip.

BACKGROUND: Several studies in adult hips have revealed the role of the gluteus medius (Gmed) and gluteus minimus (Gmin) muscles in maintaining the stability and centripetal force of the hip joint. Hip centripetality in developmental dysplasia of the hip (DDH) patients contributes to subsequent healthy hip development later in life. The purpose of this study is to investigate the relationship between Gmed and Gmin volume and centripetality of the hip in infant DDH patients. METHODS: We retrospectively enrolled 41 unilateral DDH patients (4 males, 37 females) who were treated by closed reduction from 2006 to 2016 and underwent magnetic resonance imaging at around 2 years old. Gmed, and Gmin volume was measured in magnetic resonance imaging. We defined both Gmin and Gmed together as hip abductor gluteus muscles (GMs; Gmed + Gmin). The muscle volume ratio of the affected side was calculated by dividing the GMs volume of the affected side by the contralateral side. Relationships between center-head distance discrepancy (CHDD) at 2 years old, and at 4-6 years old and GMs volume ratio were investigated by Pearson's correlation coefficient within the same patients. RESULTS: Mean age of closed reduction was 0.8 years old and mean age at MRI was 2.2 years old with a mean follow-up period of 3.7 years. Mean GMs volume in the affected side, contralateral side, and muscle volume ratio were 25.3 cm3, 27.0 cm3, and 0.94, respectively. GMs volumes were significantly higher in the contralateral side (p < 0.001). GMs volume ratio at 2 years old significantly correlated with CHDD at 4-6 years old (p < 0.05). CONCLUSION: GMs volume at 2 years old was found to be associated with later hip afferents. Promoting the healthy development of GMs by properly maintaining the infant's natural hip movement is important for the healthy hip development. LEVEL OF EVIDENCE: Level III.

Effect of temporary school closure due to COVID-19 on musculoskeletal function in elementary school children.

Objective: In 2020, coronavirus disease-2019 (COVID-19) became the cause of a pandemic. In response, the Japan Sports Agency issued warnings about secondary damage to health, such as the threat to physical and mental well-being due to the lack of exercise in this situation. In this study, we report on cross-sectional and longitudinal examinations of standing trunk flexion to evaluate how temporary long-term school closures affected musculoskeletal function in elementary school students. Patients and Methods: All children in one public elementary school in T-city during the school years 2019 and 2020 were included in this study. A digital forward flexion meter was used to measure standing trunk flexion. Results: In this study, 284 (284/289: 98.3%) and 266 (266/274: 97.1%) children in school years 2020 and 2019, respectively, were found to have valid data for cross-sectional analysis. The standing trunk flexion did not show significant differences between grades or sexes. In the longitudinal analysis, the results of the comparison of standing trunk flexion in children for two consecutive years revealed significant differences only between grades 3 and 4 (P<0.05) and between girls in grades 3 and 4 (P<0.01), but no significant differences in other grades or among boys or girls were observed. Conclusion: Initially, we expected that there would be a difference in the results of functional assessment using standing trunk flexion depending on the period of absence from school. However, the results of this study showed no significant changes in standing trunk flexion. Moreover, since children's musculoskeletal functions may be affected by various factors during the COVID-19 pandemic, they should be carefully monitored in the future.

Concentrated autologous bone marrow aspirate transplantation versus conservative treatment for corticosteroid-associated osteonecrosis of the femoral head in systemic lupus erythematosus.

Objective: To compare the outcomes of steroid-associated osteonecrosis of the femoral head in patients with systemic lupus erythematosus who underwent conservative treatment and concentrated autologous bone marrow aspirate transplantation Methods: Osteonecrosis of the femoral head was classified according to the Japanese Investigation Committee system. Concentrated autologous bone marrow aspirate transplantation was performed by aspirating the bone marrow from both iliac crests and then transplanting it to the necrotic area after the core decompression. Patients with >2-year follow-up after the concentrated autologous bone marrow aspirate transplantation in our institution (Group I) and those with >2-year follow-up after the first hospital visit in a cooperative institution (Group II) were included in this study. After a randomized matching based on age, sex, type, stage, and etiology, the collapse rate in pre-collapsed stages and total hip arthroplasty conversion rate in all stages were compared between the two groups. Results: After the matching adjustment, 33 pairs of hips were included. Preoperatively, 1, 2, 16, and 14 hips were classified as types A, B, C1, and C2, respectively, and 15, 13, 2, and 3 hips were classified as stages 1, 2, 3A, and 3B, respectively. The collapse rates in the pre-collapsed stages were 68% and 39% in Groups I and II, respectively. Total hip arthroplasty conversion rates were 33% and 45% in Groups I and II, respectively. However, Group I had significantly higher and lower conversion rates in stages 1 and 3, respectively (both P<0.05). Conclusion: Conservative treatment may be preferable in stage 1 hips. In addition, concentrated autologous bone marrow aspirate transplantation may prevent further collapse in stage 3.

Cross-Sectional Survey of Childhood Acetabular Development in Japan.

INTRODUCTION: We aimed to clarify childhood acetabular development and to identify the incidence of children's hip dysplasia in Japan using radiographs of the contralateral hip. METHODS: We performed radiological cross-sectional evaluation of hip development in 211 patients (106 boys, 211 hips) in different age groups (age range: 3-9 years). We excluded patients who complained of bilateral coxalgia at the first visit or had received a diagnosis of acetabular dysplasia. We measured the acetabular index (AI), center-edge angle (CEA), and acetabular head index (AHI) in plain radiographs taken at the first visit. RESULTS: A significant correlation was found between age and CEA in boys, but other parameters had no significant correlation. The mean AI values in boys and girls were 18 ± 3° and 20 ± 4° (p < 0.01), respectively, and the mean CEA values were 25 ± 5° and 24 ± 5° (p = 0.43), respectively. The mean AHI values in boys and girls were 83 ± 6% and 81 ± 7%, respectively (p < 0.01). Two of the 120 children (66 boys and 54 girls) aged ≥6 years old had a hip CEA < 15°; both were girls. CONCLUSIONS: We found decreased acetabular development in girls, and 4% (2/54) of girls without any history of dislocation belonged to Severin's group III. Acetabular dysplasia was observed more frequently in children from Japanese than in those from other countries. Girls with less than two standard deviations in hip dysplasia indices had an AI of 28°, an AHI of 67%, and a CEA of 14°. These reference values may be useful as prognostic indicators for hip dysplasia and OA in adulthood.

Four-year musculoskeletal examinations among elementary and junior high school students across a single city.

Objective: In 2016, Japan started conducting musculoskeletal examinations that included "limb status" of students as an essential item. Our institution implemented a unified musculoskeletal examination for all public elementary and junior high schools in T-city. In this study, we aimed to report the progress in the past 4 years. Patients and Methods: The Tsukuba Childhood Locomotive-Organ Screening Sheet (T-CLOSS), which is a questionnaire that includes some nationwide-recommended questions, was prepared and distributed to students. Results of the questionnaires were analyzed, and the orthopedic surgeon conducted examinations for the extracted items. From these questionnaires, the ratio of each item, rate of advisory for screening, and content of the advisory were investigated. Results: During 2016-2019, musculoskeletal examinations were conducted in every public schools, with nearly 20,000 students in T-city. The consultation advisory rate was 6.7% in 2019. Of the 524 students who received the third screening recommendation, the actual consultation rate was 248 (40.8%). After the third screening, the proportion of students requiring treatment and outpatient visits was 46.7% (n=248), which accounted for 1.2% of all elementary and junior high school students in the city. Conclusion: We reported the results of 4-year musculoskeletal examinations in a city. In our screening, we distributed a uniform questionnaire throughout the city, and orthopedic surgeons performed secondary examinations of identified students in all schools. This appears to be an advanced effort to prevent musculoskeletal impairment in students. We hope to conduct more sophisticated musculoskeletal examinations using our results, aiming at early detection, early treatment, and improvement of musculoskeletal function in elementary and junior high school students.

Characteristics and diagnostic factors associated with fresh lumbar spondylolysis in elementary school-aged children.

PURPOSE: We often encounter elementary school-aged children with fresh lumbar spondylolysis and non-union of bone. They may have factors that impede healing, and treatment outcomes need improvement. The purpose of this study was to investigate elementary school-aged patients with fresh lumbar spondylolysis and to identify characteristics that can aid in prompt diagnosis and proper therapy. METHODS: We retrospectively compared the characteristics of fresh lumbar spondylolysis in elementary school-aged children with those of older patients. We included patients aged 6-18 years with lower back pain and evidence of bone marrow oedema of lumbar pedicles on magnetic resonance imaging (MRI). The elementary school-aged group (group E) included 100 patients aged 6-12 years, and the senior group (group S) included 251 patients aged 13-18 years. We recorded patient sex, duration of lower back pain, injured site (lumbar level, unilateral/bilateral), presence of contralateral pars defect with evidence of high signal change on MRI (short tau inversion recovery), presence of spina bifida occulta (SBO), and follow-up treatment interruption rate. RESULTS: One-third of the patients in group E were female, and there was an even smaller proportion of females in group S. L5 lumbar spondylolysis was more common in group E. The treatment interruption rate was lower in group E. L5 SBO and contralateral pars defect were more common in group E. CONCLUSION: L5 lumbar spondylolysis, L5 SBO, and contralateral pars defect were important diagnostic factors in elementary school-aged patients. Identification of these characteristics will aid in prompt diagnosis and proper therapy.

Determining the relationship between physical status and musculoskeletal injuries in children: a cohort study.

Background: In Japan, in 2016, the School Health and Safety Act was revised and examination of extremities in addition to scoliosis became mandatory. Musculoskeletal examinations were subsequently started using a mark sheet-type questionnaire. In the present study, we aimed to analyze the relationship between physical findings and musculoskeletal problems and propose a preventive strategy for musculoskeletal injuries. Methods: In 2017, a total of 4,073 elementary and middle school students underwent direct musculoskeletal examination. In a direct examination, the following elements were included: torticollis; scoliosis; stiffness of the shoulder, elbow, hip, knee, and ankle; flexion and extension in standing position; flat foot; hallux valgus; and alignment of the upper and lower extremities. Of the 4,073 students who underwent direct examination in early 2017, only 3,754 were able to complete the mark sheet-type questionnaires in early 2018. A prospective longitudinal analysis of the data gathered was performed. Results: A total of 396 (11%) students had injuries. The ankle sprain/non-ankle sprain group comprised 119 (3%)/3,635 (97%) students, while the fracture/non-fracture group comprised 105 (2.8%)/3,650 (97.2%) students, respectively. Comparing the sprain group with the non-sprain group, ankle stiffness significantly correlated with ankle sprain in the univariable and multivariable analyses. Injuries occurred more frequently among boys, older students, students with stiff bodies, and students who were involved in sports activities of longer duration. Conclusion: Ankle stiffness was assumed to be a risk factor for ankle sprain. Stretching of the ankle might be effective for preventing ankle sprain. However, further interventional studies are needed to confirm this finding.

Relationship between exercise time and musculoskeletal problems in children.

Objectives: The purpose of this study was to evaluate the relationship between exercise time and musculoskeletal problems and to determine the appropriate amount of exercise for children in both lower- and higher-grade levels of elementary and junior high schools. Materials and Methods: Mark-sheet-type questionnaires were distributed to and collected from all elementary and junior high schools in two cities. We collected 22,494 questionnaires in total. The relationship between exercise time and musculoskeletal problems was analyzed. The χ2 test and multivariate logistic regression analysis were used for statistical analyses. Results: The mean exercise time in school, in addition to physical education time, was 3.1 hours per week. In 56% of the children, the exercise time was less than 2 hours per week, and in 13% of the children, the exercise time was more than 10 hours per week. Although the rate of sports injury increased with an increase in exercise time, the duration of one-leg stand (a test of balance and muscle strength) also increased with an increase in exercise time. The cut-off values for sports injuries in boys/girls were 2.9/2.9 hours, 4.0/2.9 hours, and 7.5/4.2 hours in lower grade elementary school, higher grade elementary school, and junior high school, respectively. Conclusions: Although an appropriate amount of exercise improves one's physical health and ability, excessive exercise leads to musculoskeletal problems. Approximately 7 hours/week of exercise is recommended for junior high school students. In elementary school, the exercise time should be carefully decided as the musculoskeletal system of the students is still immature.

Prophylactic pinning should be considered in patients at risk for slipped capital femoral epiphysis.

Background: The use of prophylactic contralateral pinning for slipped capital femoral epiphysis (SCFE) remains controversial. This study evaluated the outcome of SCFE treatment and examined the use of prophylactic pinning. Methods: The study included 44 patients (33 men, 11 women; 54 hips [right, 31; left, 23]), with mean age of 12.9 (7.3-29) years, who underwent treatment between 1986 and 2017, with follow-up for more than 6 months. Patients were divided into 3 groups: group 1 had bilateral SCFE at first presentation, group 2 developed contralateral side SCFE during follow-up, and group 3 had unilateral SCFE until final follow-up. Three patients who received prophylactic pinning were excluded. Univariate and multivariate logistic analyses were performed. Results: Overall, 93% (50/54) of hips underwent positional reduction and in situ fixation and 7.4% (4/54) underwent open reduction. Mean follow-up period was 4.8 (0.5-25) years. Groups 1, 2, and 3 had 7, 3, and 31 cases, respectively. Sex, age, and follow-up period showed no significant differences among the groups. The Rohrer index was significantly higher in group 1, the affected side posterior sloping angle (PSA) was significantly higher in group 3, and the contralateral side PSA and percentage with endocrinopathy were significantly higher in group 2. In multivariate logistic analysis, age, sex, Rohrer index, affected side PSA, and endocrinopathy were significantly correlated with bilateral SCFE. Conclusion: We recommend prophylactic contralateral side pinning in patients with risk factors of obesity, high PSA before slipping, and endocrinopathy. Careful observation until growth plate closure is required in patients without risk factors.

Proposal of a New Type of Innominate Osteotomy without the Use of Bone Graft in Children: A Preliminary Study.

Good long-term outcomes have been reported for the Salter innominate osteotomy (SIO), which is widely used to correct developmental dysplasia of the hip (DDH) in children. In this study, we describe the procedure and early outcomes of a new pelvic osteotomy termed "angulated innominate osteotomy" (AIO). METHODS: Twenty-one patients (22 hips) underwent AIO. We evaluated age at the time of surgery, operative time, blood loss, and time to bone union. Several radiographic parameters were assessed preoperatively, immediately postoperatively, and at the time of the latest examination. Measurements were compared with those of 20 previous patients who underwent SIO. The AIO is made to form an isosceles triangle. This enables 2 points of contact between the proximal and distal bone fragments, eliminating the need for a bone graft. RESULTS: Mean age at the time of surgery was 5.9 years, and the mean duration of follow-up was 30.8 months. The mean operative time was 103 minutes, mean blood loss was 33 mL, and mean time to bone union was 9.8 weeks. Immediately postoperatively, the mean "distance d" (lateral displacement of the distal fragment), mean ratio of the obturator heights (ROH), and mean lateral rotation angle (LRA) were 7.2 mm, 70.4%, and 19.3°, respectively. At the latest examination, the mean acetabular index (AI), center-edge angle (CEA), and acetabular head index (AHI) were 16.4°, 23.7°, and 85.5%, respectively, each of which were significantly improved compared with the preoperative values. Moreover, the mean postoperative iliac length difference (ILD) between the operative and contralateral sides was only 0.1 mm. Those treated with AIO had a significantly shorter operative time and time to bone union, and less blood loss, than those treated with SIO. The mean distance d, ROH, and LRA did not differ significantly from SIO results, while the mean ILD was significantly less. CONCLUSIONS: AIO is a less-invasive procedure that does not require a bone graft, and the short-term outcomes were favorable. Sufficient coverage of the acetabulum with displacement of the distal bone fragment to an extent similar to SIO can be achieved; we consider AIO a worthy surgical procedure that has the potential to provide good long-term outcomes similar to those seen with SIO. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Ten-year results of concentrated autologous bone marrow aspirate transplantation for osteonecrosis of the femoral head: a retrospective study.

BACKGROUND: Idiopathic osteonecrosis of the femoral head (ONFH) occurs at a relatively younger age. It is therefore important to prevent the resultant femoral head collapse and requirement of total hip arthroplasty in these patients. In 2003, we initiated concentrated autologous bone marrow aspirate transplantation (CABMAT), a joint-preserving treatment for ONFH, at our institution. Here, we report the long-term results of CABMAT treatment. METHODS: We retrospectively collated and analyzed the demographic and treatment data of 69 patients (109 hips) with idiopathic ONFH treated with CABMAT between April 2003 and April 2008. RESULTS: Totally, 44 patients (21 men, 23 women, 80 hips) completed the 10-year follow-up. The follow-up rate was 73.4%, and the mean follow-up period was 12.0 (range, 10.0-15.4) years. The mean age of the patients was 42.2 (range, 16.3-70.5) years. Using the Association Research Circulation Osseous (ARCO) classification system for preoperative analysis, 12, 31, 32, and 5 hips were classified as stages 1, 2, 3, and 4, respectively. The overall rate of conversion to total hip arthroplasty (THA) was 34% (27/80 hips). In a multivariate regression analysis, the preoperative stage of ONFH and the body mass index were found to correlate significantly with conversion to THA. Totally, 43 hips (of 80) were classified as belonging to the pre-collapse stage (i.e., stages 1 or 2). The overall collapse rate and the THA-conversion rate of these hips were estimated to be 49% (21/43) and 14% (6/43), respectively. CONCLUSIONS: On the basis of our long-term findings, the minimally invasive and feasible CABMAT therapy can be utilized as one of a joint-preserving treatment for ONFH.