Clinical outcomes of conservative treatment with a non-weight-bearing abduction brace for Legg-Calvé-Perthes disease

Multimodal radiomics and deep learning models for predicting early femoral head deformity in LCPD

PURPOSE

To develop a predictive model combining clinical, radiomic, and deep learning features based on X-ray and MRI to identify risk factors for early femoral head deformity in Legg-Calvé-Perthes disease (LCPD).

METHODS

This study involved 152 patients diagnosed with early unilateral LCPD across two centers between January 2013 and December 2023, and included an independent external validation set to assess generalizability. Four machine learning methods, including logistic regression (LR), random forest (RF), support vector machine (SVM), and extreme gradient boosting (XGBoost), were employed to develop radiomics deep learning signatures. The clinical-radiomics model (Clinic + Rad), clinical-deep learning model (Clinic + DL), and clinical-radiomics-deep learning model (Clinic + Rad + DL) were developed by integrating radiomics deep learning signatures with clinical variables. The best model, integrated into a nomogram for clinical application, was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

Among the four machine learning methods, XGBoost demonstrated superior performance in our patient dataset: radiomic (Rad) model (AUC, 0.786) and deep learning (DL) model (AUC, 0.803). Clinical variables such as age at onset and JIC classification were associated with early femoral head deformity (p < 0.05). The combined model incorporating clinical, radiomic, and deep learning signatures demonstrated better predictive ability (AUC, 0.853). The nomogram can assist clinicians in effectively assessing the risk of early femoral head deformity.

CONCLUSION

The Clinic + Rad + DL integrated model may be beneficial for prognostic assessment of early LCPD femoral head deformity, which is crucial for tailoring personalized treatment strategies for individual patients.

Does Flexion Varus Osteotomy Improve Radiographic Findings Compared With Patients Treated in a Brace for Late-onset Legg-Calvé-Perthes Disease?

BACKGROUND

Legg-Calvé-Perthes disease (LCPD) is a childhood hip disease characterized by osteonecrosis of the femoral head. Because severe deformity of the femoral head can cause secondary osteoarthritis in adulthood, progressive collapse should be prevented in children with a necrotic epiphysis. The prognosis of patients with LCPD generally worsens as the age at disease onset increases, and the appropriate treatment for late-onset LCPD remains unclear. Based on the limited effect of nonoperative treatment using a nonweightbearing brace, flexion varus osteotomy (FVO) was introduced in 2010 as an initial treatment for late-onset LCPD in place of brace treatment, which we used in our institution before that time.

QUESTIONS/PURPOSES

We asked, (1) Which treatment, FVO or a nonweightbearing brace, is associated with a lower likelihood of progressive femoral head collapse in children whose diagnosis of LCPD was made at the age of ≥ 8 years and who were followed for a minimum of 3 years after their intervention? (2) What proportion of patients in the brace group had surgery despite the treatment, and what percentage of children in the FVO group had a second operation to remove hardware and/or additional operations?

METHODS

The initial treatment was applied in 181 patients with LCPD between 1995 and 2018 in our institution. Patients whose disease onset was at ≥ 8 years old (late-onset LCPD) with complete clinical and radiologic data were considered potentially eligible. In 2010, treatment for these patients changed from brace treatment to FVO for all patients. A total of 35% (42 of 121) of patients who were treated with a nonweightbearing brace between 1995 and 2009 and 40% (24 of 60) of patients who were treated with FVO between 2010 and 2018 were eligible. Among patients treated with a brace, 21% (nine of 42 patients) were excluded because of hospital transfer (three patients), short-term follow-up (three), the period from onset to the first visit was ≥ 7 months (two), and inability to use the brace because of mental incapacity (one patient). In patients treated with FVO, 12% (three of 24 patients) were excluded (two patients with a period from onset to the first visit ≥ 7 months and one with a comorbidity and multiple-epiphyseal dysplasia). Among the remaining patients, 79% (33 of 42 patients) were classified into the brace group and 88% (21 of 24 patients) were classified into the FVO group for analyses. There were no overlapping patients at the timepoint when the treatment strategy for late-onset LCPD changed. In the FVO group, subtrochanteric osteotomy with 35° to 40° of flexion and 15° to 20° of varus was performed using a locking compression plate for pediatric use. Patient demographics, radiographic parameters, and the assessment of femoral head deformity using the Stulberg classification were compared between the two groups. There was a greater proportion of boys than girls in both groups (brace: 88% and FVO: 86%), and there were no differences in the distribution of genders between the groups (p = 0.82). The right side was more frequently treated in the brace group, but there was no difference in laterality between the groups (brace: 58% right and FVO: 62% left; p = 0.16). There was no difference between groups in the median age at disease onset (9.0 years [range 8.0 to 12.5 years] in the brace group and 9.6 years [range 8.0 to 12.4 years] in the FVO group; p = 0.26). There was no difference between the groups in the period of treatment from onset (1.7 ± 1.9 months in the brace group and 1.5 ± 1.5 months in the FVO group; p = 0.73) or the follow-up period (6.7 ± 2.1 years in the brace group and 6.2 ± 2.1 years in the FVO group; p = 0.41). The LCPD stage at the first visit was assessed using the modified Waldenström classification. The intraobserver and interobserver values of the modified Waldenström classification, evaluated using kappa statistics, were excellent (kappa value 0.89 [95% CI 0.75 to 0.97]; p < 0.01) and good (kappa value 0.65 [95% CI 0.43 to 0.87]; p < 0.01). The radiographic degree of collapse at the maximum fragmentation stage was assessed using the lateral pillar classification. The intraobserver and interobserver reliabilities of the lateral pillar classification were excellent (kappa value 0.84 [95% CI 0.73 to 0.94]; p < 0.01) and excellent (kappa value 0.83 [95% CI 0.71 to 0.94]; p < 0.01). The degree of femoral head deformity at the most recent follow-up examination was compared between the groups in terms of the Stulberg classification, in which Classes I and II were classified as good and Classes III through V were classified as poor. The intraobserver and interobserver reliabilities of the Stulberg classification were good (kappa value 0.74 [95% CI 0.55 to 0.92]; p < 0.01) and good (kappa value 0.69 [95% CI 0.50 to 0.89]; p < 0.01). The evaluators were involved in the patients' clinical care as part of the treating team.

RESULTS

Good radiographic results (Stulberg Class I or II) were obtained more frequently in the FVO group (76% [16 of 21 patients]) than in the brace group (36% [12 of 33 patients]), with an odds ratio of 5.6 (95% CI 1.7 to 18.5; p < 0.01). In the brace group, a subsequent femoral varus osteotomy was performed in 18% (six of 33) of patients with progressive collapse and hinge abduction, and implant removal surgery was performed approximately 1 year after the first procedure. This traditional varus osteotomy was occasionally performed in patients who were considered for conversion from nonoperative treatment before 2009 because FVO had not yet been introduced. In the FVO group, all patients (n = 21) had a second procedure to remove the implant at a mean of 10.5 ± 1.2 months postoperatively. Additional procedures were performed in 24% (five of 21) of patients, including a second FVO for progressive collapse (one patient), guided growth for a limb length discrepancy (one patient), and flexion valgus osteotomy for coxa vara in patients with a limb length discrepancy (three patients).

CONCLUSION

Our historical control study found that FVO may increase the possibility of obtaining good radiographic results (Stulberg Class I or II) compared with brace treatment for patients with late-onset LCPD, although surgical interventions after the first and second implant removal procedures may be indicated. Surgeons can consider FVO if they encounter patients with late-onset LCPD, which is a challenging condition. A larger study with long-term follow-up is needed to confirm the efficacy of FVO.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Does Prolonged Weight Relief Increase the Chances of a Favourable Outcome After Containment for Perthes Disease?

We have been treating children with Legg-Calvé-Perthes disease (LCPD) with a femoral varus osteotomy (PFVO) and weight relief till the disease evolves to the latter part of the stage of reconstitution (Stage IIIb). This entails weight relief for 18 to 24 months. We undertook this case-control study to test if a shorter period of weight relief would compromise the chance of retaining the spherical shape of the femoral head when the disease healed. Forty-one children diagnosed in the early stages of LCPD (Stages Ia, Ib, and IIa), were treated by PFVO and non-weight-bearing for a period of 6 months following surgery (6m group). Eighty-two children with LCPD matched for age, sex, and stage at surgery, who resumed weight-bearing only once they reached Stage IIIb, served as the control group (3b group). Both groups were followed up till the disease healed. The sphericity deviation score was calculated, and the height and width of the epiphysis were measured on the first radiograph designated as Stage IV. The median sphericity deviation score value at healing was 3 in the 3b group and 11 in the 6m group (P<0.001). The frequency of spherical heads was 76% in the 3b group and 49% in the 6m group (P<0.003). The Odds Ratio of the disease healing with an aspherical head in 6-month group was 3.05 (CI: 1.28 to 7.22) compared with the 3b group. The percentage increase in width of the femoral epiphysis at healing was greater in the 6 group (111.5±8.5% vs. 106.5±7.2%; P<0.001). The study confirms that containment by PFVO performed early in the course of LCPD combined with weight relief till the disease has evolved to Stage IIIb is likely to result in spherical hips in 75% of children. Reducing the period of weight relief to 6 months may yield significantly poorer results with only 49% spherical femoral heads.

Do Weightbearing Restrictions Cause Excess Weight Gain in Children With LEGG-Calvé-Perthes Disease?

BACKGROUND

Restricted weight bearing is commonly prescribed in Legg-Calvé-Perthes Disease (LCPD), raising concerns of causing overweight or obesity. This study utilizes prospectively collected data to address the following questions: (1) does body mass index (BMI) Z-score increase over the course of LCPD follow-up; (2) is having a BMI category of normal, overweight, or obese at baseline associated with BMI Z-score changes over the course of follow-up; and (3) is the duration of weight bearing restrictions (no restrictions, <3, 3 to <6, 6 to 9, or >9 mo) associated with BMI Z-score changes.

METHODS

Data of 130 children aged 5 to 12 years with unilateral early-stage LCPD were extracted from an international database. Nation-specific BMI Z-scores and percentile-based weight categories were determined, and the duration of follow-up and weight bearing restrictions were calculated. Longitudinal changes in BMI Z-scores were evaluated for the 3 study questions using mixed effects linear regression models with surgery as a covariate. Sensitivity analyses were used to determine the influence of socio-cultural background (USA vs. India) for each study question.

RESULTS

During the 35.5±15.9 months of follow-up, no statistically significant increase in BMI Z-scores was observed across the entire cohort, or following stratification by baseline weight categories or the duration of the weight bearing restriction. Sensitivity analyses indicated that patients in the USA had no change in their BMI Z-score. When stratified by weight categories, the normal weight of US children had a small increase in their BMI Z-score (0.005 per mo, 95% confidence interval: 0.0002, 0.009), but this was not seen in other BMI categories. The cohort of Indian children had a small but significant decrease in their BMI Z-score (-0.005/mo, 95% CI: -0.009, -0.0002). After stratification by weight categories, a small decrease of the BMI Z-score was observed only in the Indian overweight children (-0.016 per mo, 95% CI: -0.027, -0.005) and no other BMI category.

CONCLUSIONS

Weightbearing restrictions over the course of follow-up for our cohort of children with early-stage LCPD were not associated with clinically meaningful increases of BMI Z-scores. Weight gain is multi-factorial and probably not caused by weight bearing restrictions alone.

LEVEL OF EVIDENCE

III Diagnostic Study.

Does early and aggressive management of significant extrusion of the femoral head affect the outcome of Perthes' disease with the age of onset younger than 7 years?

BACKGROUND

Little literature exists regarding aggressive treatment of the extrusion in the early stage of the disease and the outcome at skeletal maturity. The purpose of the study was to evaluate the outcome of the disease with onset younger than 7 years, treated in the early stage of the disease, with aggressive management of significant extrusion (immediate containment with fixed abduction brace in children less than 5 years and varus derotation osteotomy in older children), and reached skeletal maturity.

METHODS

All children with the age of onset younger than 7 years of disease during active Perthes disease were prospectively followed. Children with early stages of the disease (modified Elizabethtown classification) and reached skeletal maturity were included (68 children). The extrusion of the femur head was calculated by Reimer's migration index on both sides. A migration difference 12 % or above was considered as "significant extrusion". Children without significant extrusion were treated non-operatively; children with significant extrusion were treated with varus derotation osteotomy. The final radiological outcome was assessed by the Stulberg classification and sphericity deviation score (SDS). The independent "t" test and Chi-square test were done to compare the difference between the two groups.

RESULTS

The mean age at the onset and the final follow-up was 5.7 years and 15.3 years. The frequency of significant extrusion was 57%. At the final follow-up, an excellent clinical outcome and radiological outcomes (in 88% hips) were noted. There was no significant difference in the Stulberg groups and SDS (sphericity deviation score) in both groups.

CONCLUSION

The outcome of the children who had the age of onset of the disease less than 7 years was good with early and aggressive management of the extrusion. The reversal of extrusion is associated with a similar result of non-operative children in this age group.

LEVEL OF EVIDENCE

III.

Moderate Weightbearing Restrictions Are Associated with Worse Depressive Symptoms and Anxiety in Children Aged 5 to 7 Years with Perthes Disease

BACKGROUND

Perthes disease most commonly affects children 5 to 7 years old, and nonoperative management, such as weightbearing and activity restrictions, is generally recommended. In earlier research in children aged 8 to 14 years who had Perthes disease, we found that the restrictions were associated with worse mobility, but mental health or social health measures were not linked. However, Perthes disease most commonly affects children 5 to 7 years old who are more emotionally and cognitively immature. Children in this age group are beginning school and organized sports experiences while developing meaningful social relationships for the first time. Because of such different life experiences, it is important to understand the psychosocial consequences of weightbearing and activity restrictions on this specific age group, as they may help guide choices about weightbearing restrictions and mental health support.

QUESTIONS/PURPOSES

In patients aged 5 to 7 years with Perthes disease, we asked: (1) Are weightbearing and activity restrictions associated with worse mental health, evaluated with the Patient-reported Outcome Measurement Information System (PROMIS) depressive symptoms, anxiety, and anger questionnaires? (2) Are weightbearing and activity restrictions associated with worse social health (PROMIS peer relationships measure)? (3) Are weightbearing and activity restrictions associated with worse physical health measures (PROMIS mobility, pain interference, and fatigue measures)? (4) What other factors are associated with mental, social, and physical health measures in these patients?

METHODS

Data were collected from 97 patients with a diagnosis of Perthes disease. Inclusion criteria were age 5 to 7 years at the time the PROMIS was completed, English-speaking patients and parents, in the active stage of Perthes disease (Waldenstrom Stages I, II, or III) who were recommended weightbearing and activity restrictions because of worsening hip pain, poor hip ROM, femoral head deformity, as a postoperative regimen, or if there was substantial femoral head involvement on MRI [23]. Based on their weightbearing and activity restriction regimen, patients were categorized into one of four activity restriction groups (no, mild, moderate, and severe restriction). The following pediatric parent-proxy PROMIS measures were obtained: depressive symptoms, anxiety, anger, peer relationships, mobility, pain interference, and fatigue. We excluded five patients who did not meet the inclusion criteria. Of the remaining 92 patients, 21 were in the no restriction group, 21 were in the mild restriction group, 28 were in the moderate restriction group, and 22 were in the severe restriction group at the time of PROMIS administration. ANOVA was used to compare differences between the mean PROMIS T-scores of these four groups. T-scores are computed from PROMIS survey responses, and a T-score of 50 represents the age-appropriate mean of the US population with an SD of 10. A higher T-score means more of that measure is being experienced and a lower score means less of that measure is being experienced. To address the possibility of confounding variables such as Waldenstrom stage, gender, age at diagnosis, and history of major surgery, we performed a multivariable analysis to compare the association of different weightbearing regimens and the seven PROMIS measures. This allowed us to answer the question of whether weightbearing and activity restrictions are associated with worse physical, mental, and social health measures in Perthes patients aged 5 to 7 years, while minimizing the possible confounding of the variables listed above.

RESULTS

After controlling for confounding variables such as Waldenstrom stage, gender, age at diagnosis, and history of major surgery, we found that moderate activity restriction was associated with worse depressive symptoms (β regression coefficient = 6 [95% CI 0.3 to 12]; p = 0.04) and anxiety (β = 8 [95% CI 1 to 15]; p = 0.02) T-scores than no restrictions. The mild (β = -7 [95% CI -12 to -1]; p = 0.02), moderate (β = -15 [95% CI -20 to -10]; p < 0.001), and severe (β = -23 [95% CI -28 to -18]; p < 0.001), restriction groups had worse mobility T-scores than the no restriction group. Weightbearing and activity restrictions were not associated with anger, peer relationships, pain interference, and fatigue measures. Waldenstrom Stage II disease was associated with worse pain interference than Waldenstrom Stage III (β = 7 [95% CI 0.4 to 13]; p = 0.04). A history of major surgery was associated with worse anger scores (β = 18 [95% CI 3 to 33]; p = 0.02). The child's gender and age at diagnosis had no association with any of the seven PROMIS measures.

CONCLUSION

Moderate weightbearing and activity restrictions are associated with worse depressive symptoms and anxiety in patients with Perthes disease aged 5 to 7 years, after controlling for Waldenstrom stage, gender, age at the time of diagnosis, and history of surgery. Considering the discoveries in this study and in our previous study, for patients 5 to 7 years old, we recommend that providers discuss the potential for mental health changes with moderate weightbearing restrictions with patients and their families. Furthermore, providers should monitor for worsening mental health symptoms at each follow-up visit and refer patients to a clinical child psychologist for support when appropriate. Future studies are needed to assess the effects of these restrictions on mental health over time and after patients are allowed to return to normal activities.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Development of a murine model of ischemic osteonecrosis to study the effects of aging on bone repair

Age at onset is one of the most important predictors of outcome following ischemic osteonecrosis (ON). Currently, there is no well-established animal model to study the effects of age on the repair process following ischemic ON. The purpose of this study was to further advance a murine model of ischemic ON using four age groups of mice to determine the effects of aging on revascularization and bone repair following ischemic ON. Ischemia was surgically induced in the distal femoral epiphysis of four age groups of skeletally immature and mature mice; juvenile (5 weeks), adolescent (12 weeks), adult (22 weeks), and middle age (52 weeks). Mice were euthanized at 2 days or 4 weeks post-ischemia surgery to evaluate the extent of ON, revascularization, and bone repair. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining showed extensive cell death in the epiphysis of all four age groups at 2 days post-ischemia surgery. At 4 weeks, the juvenile mice followed by the adolescent mice had significantly greater revascularization and repair of the necrotic marrow space, increased osteoblast and osteoclast numbers, and increased bone formation rates compared to the adult and middle-age mice. Faster revascularization and bone healing were observed in the skeletally immature mice compared to the skeletally mature mice following ischemic ON. The findings resemble the clinical observation of aging on bone repair following ischemic ON. The mouse model may serve as a useful tool to investigate the mechanisms underlying the age-related impairment of bone repair in adolescent and adult ON and to develop novel therapeutic strategies.

Weightbearing and Activity Restriction Treatments and Quality of Life in Patients with Perthes Disease

BACKGROUND

Weightbearing and activity restrictions are commonly prescribed during the active stages of Perthes disease. These restrictions, ranging from cast or brace treatment with nonweightbearing to full weightbearing with activity restrictions, may have a substantial influence on the physical, mental, and social health of a child. However, their impact on the patient's quality of life is not well-described.

QUESTIONS/PURPOSES

After controlling for confounding variables, we asked (1) are restrictions on weightbearing and activity associated with physical health measures (as expressed by the Patient-Reported Outcome Measurement Information System [PROMIS] mobility, PROMIS pain interference, and PROMIS fatigue) of children in the active stages of Perthes disease? (2) Are these restrictions associated with poorer scores for mental health measures (PROMIS depressive symptoms and PROMIS anxiety)? (3) Are these restrictions associated with poorer scores for social health measures (PROMIS peer relationships)?

METHODS

Between 2013 and 2020, 211 patients with Perthes disease at a single institution were assigned six PROMIS measures to assess physical, mental, and social health. Patients who met the following eligibility criteria were analyzed: age 8 to 14 years old, completion of six PROMIS measures, English-speaking, and active stage of Perthes disease (Waldenstrom Stage I, II, or III). Weightbearing and activity restrictions were clinically recommended to patients in the initial through early reossification stages of Perthes disease when patients had increasing pain, loss of hip motion, loss of hip containment, progression of femoral head deformity, increased hip synovitis, and femoral head involvement on MRI or as a postoperative regimen. Patients were categorized into four intervention groups based on weightbearing and activity regimen. We excluded 111 patients who did not meet the inclusion criteria. The following six pediatric self-report PROMIS measures were assessed: mobility, pain interference, fatigue, depressive symptoms, anxiety, and peer relationships. Of the 100 patients, 36 were categorized into the no-restriction regimen, 27 into the mild-restriction regimen, 25 into the moderate-restriction regimen, and 12 into the severe-restriction regimen at the time of PROMIS administration. The median (range) age at diagnosis was 8 years old (range 2 to 13 years). There were 85 boys and 15 girls. Eleven patients had hips in Waldenstrom Stage I, 10 were in Stage II, and 79 were in Stage III. Forty-four patients had hips classified as lateral pillar B and 47 patients as lateral pillar C. Nine patients had not reached the mid-fragmentation stage for appropriate lateral pillar classification by the time they took the PROMIS survey. ANOVA was used to compare differences between the mean PROMIS T-scores of these weightbearing/activity regimens. Results were assessed with a significance of p < 0.05 and adjusted for Waldenstrom stage, gender, age at diagnosis, and history of major surgery using multivariate regression analysis.

RESULTS

After controlling for confounding variables, the mild- (β regression coefficient -15 [95% CI -19 to -10]; p < 0.001), moderate- (β -19 [95% CI -24 to -14]; p < 0.001), and severe- (β -25 [95% CI -30 to -19]; p < 0.001) restriction groups were associated with worse mobility T-scores compared with the no-restriction group, but no association was detected for the pain interference or fatigue measures. Weightbearing and activity restrictions were not associated with mental health measures (depressive symptoms and anxiety). Weightbearing and activity restrictions were not associated with social health measures (peer relationships). Earlier Waldenstrom stage was associated with worse pain interference (β 10 [95% CI 2 to 17]; p = 0.01) and peer relationships scores (β -8 [95% CI -15 to -1]; p = 0.03); female gender was linked with worse depressive symptoms (β 7 [95% CI 2 to 12]; p = 0.005) and peer relationships scores (β -6 [95% CI -12 to 0]; p = 0.04); and earlier age at diagnosis was associated with worse peer relationships scores (β 1 [95% CI 0 to 2]; p = 0.03). History of major surgery had no connection to any of the six PROMIS measures.

CONCLUSION

We found that weightbearing and activity restriction treatments are associated with poorer patient-reported mobility in the active stages of Perthes disease after controlling for Waldenstrom stage, gender, age at diagnosis, and history of surgery. Weightbearing/activity restrictions, however, are not associated with pain interference, fatigue, depressive symptoms, anxiety, and peer relationships. Understanding how these treatments are associated with quality of life in patients with Perthes disease can aid in decision-making for providers, help set expectations for patients and their parents, and provide opportunities for better education and preparation. Because of the chronic nature of Perthes disease, future studies may focus on longitudinal trends in patient-reported outcomes to better understand the overall impact of this disease and its treatment.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Subchondral fracture of the femoral head in children: Differential diagnosis of pediatric hip pain

This report describes clinical and radiographic characteristics of two pediatric patients with a presumptive diagnosis of subchondral fracture of the femoral head made based on their clinical course and imaging findings. An 8-year-old boy and an 8-year-old girl had subchondral fracture in the femoral head without osteonecrosis, which was verified by contrast-enhanced magnetic resonance imaging. Although complete disappearance of the fracture line was confirmed in the boy, the girl had a residual femoral head deformity after conservative treatment. Subchondral fracture of the femoral head should be included in the differential diagnosis of pediatric hip pain.

Revascularization of the necrotic femoral head after traumatic open anterior hip dislocation in a child: a case report

INTRODUCTION

Avascular necrosis of the femoral capital epiphysis is the most serious complication after traumatic dislocation of the hip in children. This case report discusses the localization and revascularization of the necrotic femoral head following rarely experienced traumatic open anterior hip dislocation in children.

CASE PRESENTATION

Our patient was an 11-year-old Japanese boy who had open anterior hip dislocation sustained in a traffic accident. Reduction of the hip joint was performed in an emergency operation, and he was evaluated using serial gadolinium-enhanced magnetic resonance imaging. T1-weighted magnetic resonance images showed two bands with low signal intensity in the femoral capital epiphysis on coronal and oblique axial planes, indicating the existence of avascular osteonecrosis of the femoral head. We observed gadolinium enhancement in the central region of the epiphysis, where the area between the two bands with low signal intensity was located. Serial assessment with enhanced magnetic resonance images during a non-weight-bearing period of 1.5 years after injury showed revascularization starting from the central region and converging toward the peripheral region. Although the patient had leg-length discrepancy due to the early epiphyseal closure, non-weight-bearing treatment for the avascular osteonecrosis of the femoral head achieved a favorable outcome without any hip joint dysfunction, pain, or sign of secondary osteoarthritic change within 4.5 years after injury.

CONCLUSION

We confirmed the revascularization process of the necrotic lesion in the femoral capital epiphysis in an 11-year-old boy using serial gadolinium-enhanced magnetic resonance imaging. Conservative non-weight-bearing treatment achieved a favorable outcome.