Incidence and Risk Factors of Osteonecrosis of the Femoral Head after Cephalomedullary Nailing for Pertrochanteric Fractures: Observational Single-Center Study.

Background: The objective of this study was to investigate the incidence of osteonecrosis of the femoral head (ONFH) after cephalomedullary nailing in elderly patients with pertrochanteric fractures and to analyze the risk factors related to ONFH. Methods: A total of 689 consecutive patients with cephalomedullary nailing for pertrochanteric fractures at our hospital were recruited. Of these, 368 patients who met the inclusion criteria were finally enrolled. ONFH after cephalomedullary nailing was identified by reviewing patients' electronic charts and serial radiographs. The ONFH group was then compared with the non-ONFH group. Results: ONFH was identified in 9 of 368 patients (2.4%). The time to diagnosis of ONFH averaged 23.8 months (range, 5-54 months) after index surgery. The mean age, body mass index, and bone mineral density (T-score in femur neck) were 84.1 ± 7.1 years, 23.7 ± 3.6 kg/m2, and -3.1 ± 0.7 kg/m2, respectively. The times from injury to surgery, from admission to surgery, and operation time averaged 4.2 ± 2.7 days, 3.6 ± 2.6 days, and 87.2 ± 30.0 minutes, respectively. Among 9 patients, 3 underwent conversion arthroplasty. The ONFH group had advanced age (p = 0.029), more basicervical fracture components (p = 0.002), and inadequate reduction (p = 0.045) compared to the non-ONFH group. On multivariate analysis, advanced age (odds ratio [OR], 1.61;, p = 0.022), basicervical fracture components (OR, 24.58; p = 0.001), and inadequate reduction (OR, 4.11; p = 0.039) were identified as risk factors of ONFH. Conclusions: Although ONFH is relatively rare after cephalomedullary nailing for pertrochanteric fractures in elderly patients, its risk may increase with advanced age, basicervical fracture components, and inadequate reduction. Therefore, in patients with these risk factors, meticulous and longer follow-up is needed even after bone union.

Clinical efficacy of Femoral Neck System for treatment of unstable femoral neck fractures in young adults.

OBJECTIVE: This study was performed to evaluate the mid-term clinical efficacy of the Femoral Neck System (FNS) (DePuy Synthes, Zuchwil, Switzerland) in treating young patients with unstable Pauwels type III femoral neck fractures. METHODS: We performed a retrospective observational analysis of 21 young adults treated with the FNS. Clinical outcomes were assessed based on fracture reduction quality, Harris hip scores, and postoperative complication rates. RESULTS: The study comprised 21 patients with a mean age of 35 years (range, 20-50 years) who were followed for a mean duration of 22.8 months (range, 16-30 months). Closed reduction was unfeasible in three (14.3%) patients, each of whom required open reduction. Notable postoperative complications were avascular necrosis in two (9.5%) patients, nonunion in one (4.7%), and implant failure in one (4.7%). Each of these complications led to the requirement for total hip arthroplasty. CONCLUSION: The favorable mid-term clinical outcomes of this study indicate that the FNS is a potentially effective treatment modality for young individuals with unstable Pauwels type III femoral neck fractures.

Epidemiological investigation and diagnostic analysis of osteonecrosis of the femoral head in three northeastern provinces of China.

BACKGROUND: In this retrospective case investigation, we analysed the data of patients with osteonecrosis of the femoral head (ONFH) to reveal demographic and clinical diagnostic features of ONFH in three northeastern provinces of China and provide a reference for its prevention, diagnosis, and treatment. METHODS: We collected data from patients in Beijing Orthopaedic Hospital of Liaoning, focusing on the aetiology and diagnosis of ONFH. Medical records and self-designed questionnaires were used to collect information for statistical analysis, including age, aetiology, reason for glucocorticoid use, hospital level at first visit, and diagnosis. RESULTS: In total, 906 patients with complete medical records were included in the analysis. The mean patient age was 47.65 ± 12.12 years. The peak age distribution was in the 40s for men and the 50s for women. Among the total cohort, 72 patients (7.95%; 40 men and 32 women) had traumatic ONFH, 198 (21.85%; 131 men and 67 women) had steroid-induced ONFH, 230 (25.39%; 121 men and 109 women) had idiopathic ONFH, and 406 (44.81%; 397 men and 9 women) had alcohol-induced ONFH. Six hundred and twenty patients were diagnosed with ONFH at the first visit, while 286 patients were misdiagnosed, with a diagnosis rate of 68.43%. The diagnosis rate at the first visit in tertiary hospitals was 76.14%. The diagnosis rate at the first visit in second-class hospitals was 52.07%.ONFH was most likely to be misdiagnosed as lumbar disc herniation. CONCLUSIONS: Most patients with ONFH in three northeastern provinces of China were middle-aged, male, and had alcohol-induced ONFH. The misdiagnosis rate of ONFH at the first visit was very high, especially for misdiagnosis of lumbar disc herniation, indicating that the diagnosis of ONFH requires further improvement.

Subtrochanteric fracture after core decompression for osteonecrosis of the femoral head: a case report and literature review.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a common clinical disease. Improper treatment can lead to femoral head collapse and hip joint dysfunction. Core decompression is particularly important for early ONFH. However, subtrochanteric fractures after core decompression cause some clinical problems. CASE PRESENTATION: This article describes a 34-year-old male patient with early ONFH. After core decompression, he suffered a subtrochanteric fracture of the femur while bearing weight on the affected limb when going up stairs. He was subsequently treated with open reduction and intramedullary nail fixation. CONCLUSION: When core decompression is used to treat ONFH, the location or size of the drill hole, whether a tantalum rod or bone is inserted, and partial weight-bearing of the affected limb may directly affect whether a fracture occurs after surgery. It is hoped that this case report can provide a reference for clinical orthopedic surgeons in the treatment of early ONFH.

Unilateral avascular necrosis of the right hip in an HIV patient with tearing of the rectus femoris and adductor longus muscles.

A man in his 20s with a medical history of syphilis, chlamydia and HIV presented to the emergency department (ED) with 2 months of right hip pain and was found to have advanced avascular necrosis (AVN) of the right femoral head with secondary haemorrhage. The patient lacked the common risk factors of AVN in patients with HIV (PWH): ≥10 years of HIV diagnosis, extended duration on highly active antiretroviral therapy, trauma, corticosteroid use, alcohol abuse, systemic lupus erythematosus, obesity, smoking and dyslipidaemia. Given the extensive destructive changes in the hip joint and muscles, a right hip resection arthroplasty was performed, and the patient recovered well postoperatively. This case presents a learning opportunity for understanding bone pathologies in PWH and offers clinical guidance for the management of HIV-infected patients with a focus on optimising bone health.

[Avascular necrosis of the hip secondary to long-standing COVID]. / Necrosis avascular de cadera secundaria a COVID de larga duración.

Long COVID is a term used to describe the long-terms effects of COVID-19 infection that continue for weeks or months after the patient has recovered from COVID-19. Long COVID is defined by the persistence of symptoms beyond 12 weeks from the onset of the disease. Corticosteroids are part of the treatment in this period with good results in controlling the disease; however, it is a predisposing factor for the development of avascular necrosis. We present a clinic case of a young man of 39 years old with diagnosis of avascular necrosis in his left hip, before the administration of corticosteroids for the treatment of COVID-19. There is a lack of consensus about the dosage and duration of steroids required to develop avascular necrosis. Some authors have reported that cumulative dose of 2,000 mg prednisone (or its equivalent) was required for avascular necrosis development. For patients with advanced avascular necrosis stages total hip arthroplasty is an attractive option with excellent outcomes in terms of pain relief and survivorship.

El COVID de larga duración es un término que describe la enfermedad en pacientes que se recuperaron de una infección por COVID-19 y reportan síntomas por más de 12 semanas. Los corticosteroides forman parte del tratamiento en este período con buenos resultados en el control de la enfermedad; sin embargo, el uso de este grupo de medicamentos se ha descrito como un factor de riesgo para el desarrollo de necrosis avascular. Se describe el caso clínico de un paciente masculino de 39 años con diagnóstico de necrosis avascular de la cadera izquierda posterior a la administración de corticosteroides para el tratamiento de COVID-19. La dosis de esteroides capaz de provocar necrosis avascular no está clara o bien descrita; sin embargo, existen reportes en la literatura donde se habla de dosis de 2,000 mg de prednisona (o equivalentes) para su desarrollo. El tratamiento de la necrosis avascular tiene como objetivo el alivio del dolor, retardar la progresión del cuadro, prevenir el colapso en etapas tempranas y restaurar la función articular. La artroplastía o recambio total de cadera parece ser una excelente opción de tratamiento quirúrgico para aquellos pacientes en etapas avanzadas.

Research progress in the pathogenesis of hormone-induced femoral head necrosis based on microvessels: a systematic review.

Hormonal necrosis of the femoral head is caused by long-term use of glucocorticoids and other causes of abnormal bone metabolism, lipid metabolism imbalance and blood microcirculation disorders in the femoral head, resulting in bone trabecular fracture, bone tissue necrosis collapse, and hip dysfunction. It is the most common type of non-traumatic necrosis of the femoral head, and its pathogenesis is complex, while impaired blood circulation is considered to be the key to its occurrence. There are a large number of microvessels in the femoral head, among which H-type vessels play a decisive role in the "angiogenesis and osteogenesis coupling", and thus have an important impact on the occurrence and development of femoral head necrosis. Glucocorticoids can cause blood flow injury of the femoral head mainly through coagulation dysfunction, endothelial dysfunction and impaired angiogenesis. Glucocorticoids may inhibit the formation of H-type vessels by reducing the expression of HIF-1α, PDGF-BB, VGEF and other factors, thus causing damage to the "angiogenesis-osteogenesis coupling" and reducing the ability of necrosis reconstruction and repair of the femoral head. Leads to the occurrence of hormonal femoral head necrosis. Therefore, this paper reviewed the progress in the study of the mechanism of hormone-induced femoral head necrosis based on microvascular blood flow at home and abroad, hoping to provide new ideas for the study of the mechanism of femoral head necrosis and provide references for clinical treatment of femoral head necrosis.

[Correlation analysis between combined deflection angle and osteonecrosis of femoral head after femoral neck fracture].

Objective: To evaluate the correlation between pelvic incidence (PI) angle, hip deflection angle (HDA), combined deflection angle (CDA) and osteonecrosis of the femoral head (ONFH) after femoral neck fracture, in order to explore early predictive indicators for ONFH occurrence after femoral neck fracture. Methods: A study was conducted on patients with femoral neck fractures who underwent cannulated screw internal fixation between December 2018 and December 2020. Among them, 208 patients met the selection criteria and were included in the study. According to the occurrence of ONFH, the patients were allocated into ONFH group and non-NOFH group. PI, HDA, and CDA were measured based on the anteroposterior X-ray films of pelvis and axial X-ray films of the affected hip joint before operation, and the differences between the two groups were compared. The receiver operating characteristic curve (ROC) was used to evaluate the value of the above imaging indicators in predicting the occurrence of ONFH. Results: Among the 208 patients included in the study, 84 patients experienced ONFH during follow-up (ONFH group) and 124 patients did not experience ONFH (non-ONFH group). In the non-ONFH group, there were 59 males and 65 females, the age was 18-86 years (mean, 53.9 years), and the follow-up time was 18-50 months (mean, 33.2 months). In the ONFH group, there were 37 males and 47 females, the age was 18-76 years (mean, 51.6 years), and the follow-up time was 8-45 months (mean, 22.1 months). The PI, HDA, and CDA were significantly larger in the ONFH group than in the non-ONFH group ( P<0.05). ROC curve analysis showed that the critical value of PI was 19.82° (sensitivity of 40.5%, specificity of 86.3%, P<0.05); the critical value of HDA was 20.94° (sensitivity of 77.4%, specificity of 75.8%, P<0.05); and the critical value of CDA was 39.16° (sensitivity of 89.3%, specificity of 83.1%, P<0.05). Conclusion: There is a correlation between PI, HDA, CDA and the occurrence of ONFH after femoral neck fracture, in which CDA can be used as an important reference indicator. Patients with CDA≥39.16° have a higher risk of ONFH after femoral neck fracture.

Evaluation of the long-term patient-reported outcomes after hip arthroplasty or joint preserving with Sugioka femoral osteotomy in patients with femoral head osteonecrosis.

PURPOSE: This study retrospectively evaluated long-term clinical outcomes and patient-reported outcome measures (PROMs) in patients with osteonecrosis of the femoral head (ONFH) who underwent transtrochanteric rotational osteotomy (TRO), curved varus osteotomy (CVO), and total hip arthroplasty (THA). METHODS: We retrospectively reviewed the 109 hips in 96 patients (46 men, 50 women) who underwent CVO, TRO, or THA for ONFH treatment. The mean follow-up period for the TRO, CVO, and THA groups was 14.8, 11.5, and 13.3 years, respectively. RESULTS: The THA conversion rate of the TRO patients was significantly higher than that of the patients with CVO, and the final clinical scores in the patients with TRO did not improve compared with preoperative scores. Postoperative PROMs showed that the total and pain scores of the patients with THA were significantly higher than those of patients with TRO and CVO, while the PROM score did not change between patients with TRO and CVO. The analysis further showed that the preoperative type C2, stage 3A, or postoperative type C1 and C2 were significant predictors of decreased final PROM scores. CONCLUSION: This study found that CVO and THA are clinically effective treatments for ONFH, with significant improvements compared with preoperative scores. However, THA was associated with significantly higher PROMs and pain scores than those of CVO and TRO in long-term follow-up. Furthermore, our results suggest that postoperative PROMs depend mainly on the preoperative level of collapse and postoperative transposed intact ratio of the articular surface of the femoral head.

Intraoperative Epiphyseal Perfusion Monitoring Does Not Reliably Predict Osteonecrosis Following Treatment of Unstable SCFE.

BACKGROUND: Avascular necrosis (AVN) remains the most dreaded complication of unstable slipped capital femoral epiphysis (SCFE) treatment. Newer closed reduction techniques (with perfusion monitoring) have emerged as a technically straightforward means to address residual SCFE deformity while still minimizing the risk of osteonecrosis. However, limited data exists regarding the reliability of intraoperative epiphyseal perfusion monitoring to predict the development of AVN. The purpose of this study was to evaluate its reliability. METHODS: We retrospectively reviewed all patients with unstable SCFE who underwent closed or open reduction with epiphyseal perfusion monitoring using an intracranial pressure (ICP) probe from 2015 to 2023 at a single institution with a minimum 6-month radiographic follow-up. Demographic, clinical, and radiographic data were recorded, including duration of symptoms, type of reduction, capsulotomy performed, presence of a waveform on ICP monitoring after epiphyseal fixation, and development of AVN on follow-up radiographs. RESULTS: Our cohort included 33 hips (32 patients), of which 60.6% (n=20) were male. The average age was 12.5±1.8 years, with a median follow-up of 15.8 months. Eleven hips were treated with open reduction using the modified Dunn technique (10 hips) or anterior approach (1 hip), and 22 hips were treated with inadvertent (5 hips) or purposeful closed reduction using the Leadbetter technique (17 hips). Overall, 8 of the 33 hips in our series (24.2%) developed AVN, 6 of which (20%) had a pulsatile waveform on intraoperative epiphyseal perfusion monitoring. The overall rate of AVN after closed reductions was 31.8% (7 of 22 hips); the incidence of AVN after closed reduction with a detectable waveform was 30% (6 of 20 hips). There was no significant association between time to surgery ( P =0.416) or type of reduction ( P =0.218) and the incidence of AVN. CONCLUSIONS: In this series, intraoperative epiphyseal perfusion monitoring did not reliably predict the development of osteonecrosis. To our knowledge, this is the first study to report AVN after demonstrable intraoperative epiphyseal perfusion following closed reduction of unstable slips. LEVEL OF EVIDENCE: Level IV: case series-therapeutic study.

Is there still an indication for the Birmingham Hip Resurfacing in femoral head osteonecrosis?

PURPOSE: Osteonecrosis of the femoral head (ONFH) is a progressive hip disease. Hip resurfacing arthroplasty (HRA) is a preferred surgical procedure among hip arthroplasty performed in young patients. The aim of this study is to show the long-term clinical and radiological results of HRA procedures performed for patients suffering from ONFH. METHODS: Forty-five patients who underwent hip resurfacing with the diagnosis of femoral head osteonecrosis were included in the study. The Harris Hip Score (HHS) was used for clinical scoring of the patients. The blood chromium, cobalt, white blood cell (WBC) count, and CRP levels of patients were checked. Ultrasonography (USG) was performed for all patients at mid-term control checked for pseudo-tumours. For the radiological evaluation, acetabular inclination, stem shaft angle, prothesis-to-neck ratio, osteolysis zones, and heterotopic ossification were used. RESULTS: The mean age of the patients was 46.6 ± 9.3 years, and the mean follow-up period was 11.83 ± 2.9 years. The mean HHS was 90.3 ± 12.8 for final follow-up. The mean WBC value was 8.2 109/L, mean CRP value was 6.3 mg/L, mean chromium value was 4.9 µg/L, and mean cobalt value was 1.8 µg/L. Inclination changing 0.2°(p = 0.788), stem shaft angle changing 0.7°(p = 0.424), and neck-to-prosthesis ratio changing 0.01°(p = 0.075). No pseudo-tumours were detected in any patients in USG examination. CONCLUSION: HRA provides long-term implant survival and excellent clinical outcomes for end-stage ONFH patients with low complication rates.

Analysis of the natural collapse course of non-traumatic osteonecrosis of the femoral head based on the matrix model.

BACKGROUND: There are many predictions about the progression of natural collapse course of osteonecrosis of the femoral head. Here, we aimed to combine the three classical prediction methods to explore the progression of the natural collapse course. METHODS: This retrospective study included 127 patients admitted to our hospital from October 2016 to October 2017, in whom the femoral head had not collapsed. Logistic regression analysis was performed to determine the collapse risk factors, and Kaplan-Meier survival curves were used for femoral head survival analysis. The collapse rate of the femoral head was recorded within 5 years based on the matrix model. The specificity of the matrix model was analyzed using the receiver operating characteristic curve. RESULTS: A total of 127 patients with a total of 202 hips were included in this study, and 98 hips collapsed during the follow-up period. Multivariate logistics regression analysis showed that the predictive ability of the matrix model was stronger than Association Research Circulation Osseous staging, Japanese Investigation Committee classification, and area (P < 0.05). Kaplan-Meier survival curve showed that the median survival time of femoral head in patients was 3 years. The result of the receiver operating characteristic curve analysis showed that the area under the curve (AUC) of the matrix model had better predictive value (AUC = 0.771, log-rank test: P < 0.001). CONCLUSION: We creatively combined the three classical prediction methods for evaluating the progression of the natural collapse course based on the matrix model and found that the higher the score of the matrix model, the higher the femoral head collapse rate. Specifically, the matrix model has a potential value in predicting femoral head collapse and guiding treatment selection.

Femoral neck system versus multiple cannulated screws for the fixation of Pauwels classification type II femoral neck fractures in older female patients with low bone mass.

BACKGROUND: Femoral neck fractures in older adult patients are a major concern and often necessitate surgical intervention. This study compared the clinical outcomes of 2 surgical techniques: the femoral neck system (FNS) and cannulated compression screws (CCSs). METHODS: A total of 40 female patients (mean age 73.50 ± 11.55 years) with femoral neck fractures of Pauwels classification type II and receiving surgical fixation between 2020 and 2022 were enrolled. The patients were categorized into an FNS group (n = 12) or a CCS group (n = 28), and surgical duration, intraoperative blood loss, length of hospital stay, and incidence of postoperative adverse events were analyzed. RESULTS: No significant intergroup differences in demographic characteristics were discovered. The mean surgical duration for all patients was 52.88 ± 22.19 min, with no significant difference between the groups. However, the FNS group experienced significantly higher intraoperative blood loss (P = 0.002) and longer hospital stay (P = 0.023) than did the CCS group. The incidence of osteonecrosis was higher in the CCS group, whereas the incidence of nonunion or malunion was higher in the FNS group. The surgical method did not appear to be a significant risk factor. The main risk factor for revision surgery was longer duration until the first adverse event (P = 0.015). CONCLUSION: The FNS does not appear to provide superior surgical outcomes compared with CCSs in older adult women with Pauwels classification type II femoral neck fractures. A longer duration between surgical fixation and the first adverse event before stabilization of the fracture site may be a risk factor for revision surgery.

Effects of the location of both anterior and lateral boundaries of the necrotic lesion on collapse progression in osteonecrosis of the femoral head.

BACKGROUND: The location of the lateral boundary of the necrotic lesion to the weight-bearing portion of the acetabulum (Type classification) is an important factor for collapse in osteonecrosis of the femoral head (ONFH). Recent studies also reported the significance of the location of the anterior boundary of the necrotic lesion on the occurrence of collapse. We aimed to assess the effects of the location of both anterior and lateral boundaries of the necrotic lesion on collapse progression in ONFH. METHODS: We recruited 55 hips with post-collapse ONFH from 48 consecutive patients, who were conservatively followed for more than one year. Using a plain lateral radiograph (Sugioka's lateral view), the location of the anterior boundary of the necrotic lesion to the weight-bearing portion of the acetabulum was classified as follows: Anterior-area I (two hips) occupying the medial one-third or less; Anterior-area II (17 hips) occupying the medial two-thirds or less; and Anterior-area III (36 hips) occupying greater than the medial two-thirds. The amount of femoral head collapse was measured by biplane radiographs at the onset of hip pain and each follow-up period, and Kaplan-Meier survival curves with collapse progression (≥1 mm) as the endpoint were produced. The probability of collapse progression was also assessed by the combination of Anterior-area and Type classifications. RESULTS: Collapse progression was observed in 38 of the 55 hips (69.0%). The survival rate of hips with Anterior-area III/Type C2 was significantly lower. Among hips with Type B/C1, collapse progression occurred more frequently in hips with Anterior-area III (21 of 24 hips) than in hips with Anterior-area I/II (3 of 17 hips, P < 0.0001). CONCLUSIONS: Adding the location of the anterior boundary of the necrotic lesion to Type classification was useful to predict collapse progression especially in hips with Type B/C1.

Sclerosis rim volume ratio and Japanese Investigation Committee classification as predictive factors for femoral head collapse progression after non-vascularized fibular grafting in osteonecrosis patients.

OBJECTIVE: The purpose of this retrospective cohort study was to determine the relationship between sclerosis rim volume ratio (SVR) and the progression of femoral head collapse after non-vascularized fibular grafting (NVFG) surgery in patients with osteonecrosis of the femoral head (ONFH), investigating risk factors associated with femoral head collapse progression and establishing a predictive model to enhance clinical decision-making. METHODS: ONFH patients who underwent NVFG between January 2008 and December 2021 were analyzed retrospectively to assess the risk of post-operative collapse progression (collapse >2 mm). A logistic regression model was used to evaluate the independent risk factors associated with collapse progression, including age, sex, etiology, affected side, Japanese Investigation Committee classification (JIC), and the sclerosis rim volume ratio (SVR). SVR values was collected from three weight-bearing columns, namely SVR1, SVR2, and SVR3, respectively. RESULTS: 57 patients with 64 hips who had undergone NVFG and were followed up for at least one year were included. During the follow-up, collapse＞2 mm occurred in 30 hips (46.88%). Multivariable analysis revealed that JIC (p =0.037) and SVR1 (p = 0.04) were independent risk factors for collapse progression after NVFG. The results of the receiver operating characteristic (ROC) analysis indicated that the aforementioned indices provided a satisfactory prediction of early femoral head collapse progression in ONFH patients after NVFG. The regression model using the above two indicators as a composite index showed satisfactory performance in predicting early postoperative femoral head collapse progression, with an area under the curve (AUC) of 84.6%. CONCLUSIONS: SVR is significant predictor of post-operative collapse progression following NVFG, and the composite index provides an optimal predictive value for femoral head collapse progression after surgery.

Risk factor analysis of femoral avascular necrosis after operation for Tönnis grade IV developmental dysplasia of the hip.

PURPOSE: We explored the risk factors for avascular necrosis (AVN) after surgery using open reduction, pelvic osteotomy, and femoral osteotomy for Tönnis grade IV developmental dysplasia of the hip (DDH). METHODS: In this retrospective study, we collected data of patients with Tönnis grade IV DDH treated with open reduction and pelvic osteotomy combined with femoral osteotomy from January 2012 to May 2020. The patients were divided into the AVN group and non-AVN group using the Kalamchi-MacEwen classification system. The clinical and imaging data of the two groups were collected, and the possible risk factors were included in the analysis. Univariate and multivariate logistic regression analyses were used to identify the independent risk factors and odds ratios of AVN. RESULTS: In all, 254 patients (mean age; 2.6±0.9 years, 278 hips) were included. The mean follow-up time was 3.8±1.5 years. A total of 89 hips (32%) were finally classified as AVN (Kalamchi-MacEwen II-IV). Univariate analysis showed significant associations with AVN for age (p=0.006), preoperative femoral neck anteversion (FAV) (p<0.001), femoral osteotomy length to dislocation height ratio (FDR) <1 (p<0.001), and the epiphyseal ossific nucleus diameter to the neck diameter ratio (ENR) <50% (p=0.009). Multivariate logistic regression analysis showed that only excessive preoperative FAV (OR: 1.04; 95% CI: 1.02-1.05; p<0.001) and FDR<1 (OR: 3.58; 95% CI: 2.03-6.31; p<0.001) were independent risk factors for femoral head necrosis. CONCLUSION: Excessive preoperative FAV and FDR<1 are important risk factors for femoral AVN after open reduction, pelvic osteotomy, and femoral osteotomy for Tönnis grade IV DDH. For children with DDH with high dislocation and excessive FAV, clinicians should fully evaluate their condition and design more personalized treatment programs to prevent AVN.

Pathological fracture increases the risk of unsatisfactory functional results and avascular necrosis in children with proximal femur simple bone cysts.

INTRODUCTION: Proximal femur simple bone cysts (SBCs) are rare in children, but with a risk of pathological fractures and the associated poor outcomes. This study aimed to evaluate the functional and radiographic outcomes of children with proximal femur SBCs. PATIENTS AND METHODS: 38 children with proximal femur SBCs treated surgically at our department, West China hospital, were enrolled in the study. Patients were divided into two groups according to whether pathological fractures presented before treatment. The non-fracture group received treatment of open curettage, cavity electrocauterization, bone grafting, and fixation (proximal femoral plate, intramedullary nail or Kirschner wire). The pathological fracture group received the same procedures of curettage, electrocauterization, grafting, and fixation. Autogenous iliac bone grafting was done in all cases, and the artificial bone was used as a supplementary based on the size of the cavity. Postoperatively, all patients underwent hip spica or similar orthosis immobilization for six weeks and received the same rehabilitation program after the removal of hip spica. Patients were evaluated by two independent observers, including the functional results based on the Ratliff's criteria, avascular necrosis, healing rate based on the Neer scoring system, coxa vara, and premature physeal arrest. We described the good outcome in Ratliff's criteria as "Satisfactory results", and fair and poor outcomes as "Unsatisfactory results." Grade 1 and grade 2 Neer results were termed as failures in treatment, and grades 3 and 4 were considered successes and healing. RESULTS: 38 patients with 38 hips (18 on the left side and 20 on the right side) were evaluated, including 9 females and 29 males, with a mean age of 9.0±2.6 years old (range, 5 to 14 years). There was no significant difference between these two groups in the baseline data of gender, age, side, grafting, staging, and fixation methods. The rate of unsatisfactory functional results in the pathological fractures group was 56.3% (9/16), significantly higher than that in patients without fracture (22.7%, 5/22. p= 0.047). There was also a significant difference in avascular necrosis of the femoral head between the pathological fractures group (7/16) and the group without fracture (2/22, p=0.021). Thirty cases presented with healing, including 13 in the fractures group and 17 in the non-fracture group (p=1.000), and eight cases were graded as failures (2 cases of grade 1 and 6 cases of grade 2). There were also no significant differences between these two groups in premature physeal arrest (2 in fracture group and 1 in non-fracture group, P=0.562), and Coxa vara (3 in the fracture group and 0 in non-fracture group, P=0.066). CONCLUSIONS: Pathological fracture significantly increases the risk of unsatisfactory functional results and avascular necrosis of the femoral head in patients with femoral neck SBCs. Prophylactic treatment and fixation of SBCs in weight bearing proximal femur region is better to manage without complications than managing with pathological fractures.

Is COVID-19 an independent risk factor for the development of avascular necrosis of the hip? A retrospective study to evaluate the factors associated with avascular necrosis of the hip in patients who had COVID-19 infection.

PURPOSE: The cumulative effect of hyper-coagulative COVID-19 disease and using steroids leads to increased avascular necrosis (AVN) hip incidence. This study aims to correlate the various factors of COVID-19 infection with the occurrence of AVN hip. METHODS: It is a retrospective cross-sectional study of non-traumatic AVN hip patients with a history of COVID-19 infection. A total number of 50 patients satisfied the inclusion criteria. The following details were obtained: (a) patient's demographics, (b) COVID-19: interval of infection and groin pain, duration of symptoms, severity, steroid intake, (c) AVN hip: involved side, Ficat-Arlet staging. RESULTS: The mean age was 36.3 years (range: 20-60), and body mass index (BMI) was 25.13 kg/m2 (range: 18.50-31.50). There were 45 males and five females. Sixty percent (30) of patients managed at home, 24% (12) required admission into the ward, 2% (1) were in ICU only, and 14% (7) admitted to both ICU and ward. The mean interval of COVID-19 infection and onset of hip pain was 359.02 days (range: 10-822 days). Thirty-eight percent (19) patients required steroids (injection and oral), 46% (23) took steroids (oral only), whereas 16% (8) recovered without steroids. The stage of AVN correlated with the severity of COVID-19 infection (p-value -0.038) and significant improvement in VAS and HHS after treatment in each stage. The mean follow-up was 9.79 months (6-19 months). CONCLUSION: A low-dose steroid intake with moderate to severe COVID-19 infection produces an additive effect on the development of AVN hip. Most affected individuals were adult males, and stage II AVN was the most common, managed with bisphosphonates and core decompression for short intervals.

The Duration of Hardware Retention After Radiologic Union of Surgically Treated Femoral Neck Fractures in Children May Predict the Aggravation or Occurrence of Avascular Necrosis of the Femoral Head or Neck After Hardware Removal.

BACKGROUND: The incidence of aggravation or occurrence of avascular necrosis (AVN) following hardware removal in surgically treated pediatric femoral neck fractures who achieved radiologic consolidation is unknown. This study aimed to investigate the risk factors for this complication. METHODS: Seventy-one pediatric (mean age: 9.8±3.9 y) were retrospectively analyzed. Risk factors (age, sex, laterality, severity of initial displacement, type of fracture, time from trauma to reduction, reduction and fixation method, quality of reduction, time required to achieve radiologic union, duration of hardware retention, presence of AVN before hardware removal and follow-up time) were recorded. The severity of AVN was assessed based on radiographs with Ratliff's classification. RESULTS: Following hardware removal, the aggravation/occurrence of AVN was detected in 11 hips (15.5%). Among the 5 hips (7%) with aggravation of AVN, 1 (1.4%) with type II AVN and 3 (4.2%) with type III AVN exhibited aggravation of type I AVN, while the remaining hip (1.4%; type I) showed enlargement of the involved AVN area. Six hips (8.5%) developed AVN following hardware removal: 2 (2.8%) were classified as type I and 4 (5.6%) as type III. Receiver operating characteristic curve analysis indicated that hardware retention >7 months after union is associated with a decreased rate of aggravation or occurrence of AVN of the femoral neck or head following hardware removal. CONCLUSIONS: The incidence of aggravation or occurrence of AVN following hardware removal in surgically treated pediatric femoral neck fractures is 15.5%; hardware retention >7 months after radiologic union may reduce the risk of aggravation or occurrence of AVN of the femoral neck or head postimplant removal. LEVEL OF EVIDENCE: Level III.

Complete Repair of Osteonecrosis of the Femoral Head After Basicervical Femoral Neck Rotational Osteotomy: A Case Report.

CASE: We present a 28-year-old female patient who developed left hip pain and was diagnosed with osteonecrosis of the femoral head (ARCO stage II). The patient underwent a basicervical femoral neck rotational osteotomy (BFNRO) combining surgical hip dislocation technique and extended retinacular soft-tissue flap technique. She was followed up for 53 months and exhibited complete repair of the necrotic area, with normal hip range of motion, gait, and excellent hip functional scores. CONCLUSION: The BFNRO procedure, by rotating the necrotic area of the femoral head out of the weight-bearing zone, has the potential to achieve complete repair of the necrotic area.