Initial MRI findings of non-traumatic osteonecrosis of the femoral head in renal allograft recipients

Magnetic resonance imaging screening for osteonecrosis of the femoral head after coronavirus disease 2019

OBJECTIVES

Systemic steroid administration has been suggested for the treatment of coronavirus disease 2019 (COVID-19), but the occurrence of osteonecrosis of the femoral head (ONFH) was one of the concerns for this treatment. This study aimed to use magnetic resonance imaging (MRI) to assess the incidence of ONFH after the treatment for COVID-19.

METHODS

The study included 41 patients who were hospitalized and treated for pneumonia or other COVID-19-induced diseases. We conducted interviews with these patients regarding hip pain and performed MRI screenings for ONFH. The incidence and timing of ONFH after COVID-19 treatment were investigated.

RESULTS

Of the 41 patients, one died of pneumonia and the remaining patients did not complain of hip pain. MRI screening was performed for 26 patients, and asymptomatic ONFH was detected in one patient (3.8%) whose ONFH appeared 1 month after the COVID-19 infection.

CONCLUSIONS

Our MRI screening of ONFH in post-COVID-19 patients revealed asymptomatic ONFH, which would not have been identified without active screening. Physicians should be aware that ONFH may occur in patients after treating COVID-19.

Outcomes of Hybrid Total Hip Arthroplasty for Subchondral Insufficiency Fracture of the Femoral Head

Background

The purpose of this study was to evaluate functional outcomes, radiologic results, and complications after hybrid total hip arthroplasty (THA) in patients with subchondral insufficiency fractures (SIFs) of the femoral head.

Methods

From June 2009 to December 2020, among 985 patients who underwent hybrid THA at our hospital, 19 patients diagnosed with SIF through a retrospective chart review were included. Those under 50 years of age, with radiographic findings of osteonecrosis on the contralateral side of surgery, a history of organ transplantation, and alcohol abuse, were excluded. Functional evaluation was performed using a modified Harris Hip Score (HHS). After surgery, inclination and anteversion of the acetabular cup and version of the femoral system were measured using postoperative x-ray. The outpatient follow-up was performed at 6 weeks, 3 months, 9 months, and 12 months after surgery and every year thereafter. Complications including dislocation, implant loosening, stem subsidence, and periprosthetic infection were observed on follow-up radiographs.

Results

The average follow-up time was 29.3 ± 9.1 months (range, 24-64 months) with no loss to follow-up. The mean modified HHS was 83.4 ± 9.6 (range, 65-100) at the last outpatient clinic follow-up. The average inclination of the acetabular cup was 41.9° ± 3.4° (range, 37°-48°), and the anteversion was 27.5° ± 6.7° (range, 18°-39°). The version of the femoral stem was 19° ± 5.7° (range, 12°-29°). There was no case of intraoperative fracture. There were no cases of dislocation, loosening of the cup, subsidence of the femoral stem, intraoperative or periprosthetic fracture, or periprosthetic infection on the follow-up radiographs.

Conclusions

In our study, hybrid THA showed favorable outcomes in patients diagnosed with SIF, and there were no further special considerations as for THA performed due to other diseases or fractures.

Association between magnitude of femoral head collapse and quality of life in patients with osteonecrosis of the femoral head

OBJECTIVES

The magnitude of femoral head collapse (MFHC) is one of the criteria for staging osteonecrosis of the femoral head (ONFH). The present study aimed to clarify the relationship between MFHC and hip pain or functional quality of life (QOL) scores in patients with ONFH.

METHODS

Seventy patients with ONFH who had femoral head collapse without osteoarthritic changes were divided into four groups based on MFHC by 1 mm. Pain was assessed using the visual analogue scale (VAS). QOL was evaluated using patient-reported outcome measures such as the Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ), Oxford Hip Score (OHS), and Short Form-12 Health Survey, version 2 (SF-12v2). We also explored the relationship between MFHC and QOL.

RESULTS

Pain score and satisfaction score in the VAS, JHEQ pain subscale, JHEQ movement subscale, and JHEQ total score were significantly associated with MFHC, and no significant differences were found between groups in any subscale or total score for OHS and SF-12v2.

CONCLUSION

In patients with ONFH, differences in MFHC by 1 mm were associated with deterioration of some pain VAS and QOL outcomes.

Osteonecrosis of the Knee: Not all Bone Edema is the Same

Knee pain is among the most common complaints that an orthopedic surgeon may see in practice. It is often worked up with X-rays and MRI, leading to a myriad of potential diagnoses ranging from minimal edema patterns to various types of osteonecrosis. Similarities in certain causes can pose diagnostic challenges. The purpose of this review was to present the 3 types of osteonecrosis observed in the knee as well as additional causes to consider to help aid in the diagnosis and treatment..

The effect of genetically modified platelet-derived growth factor-BB over-expressing mesenchymal stromal cells during core decompression for steroid-associated osteonecrosis of the femoral head in rabbits

BACKGROUND

Approximately one third of patients undergoing core decompression (CD) for early-stage osteonecrosis of the femoral head (ONFH) experience progression of the disease, and subsequently require total hip arthroplasty (THA). Thus, identifying adjunctive treatments to optimize bone regeneration during CD is an unmet clinical need. Platelet-derived growth factor (PDGF)-BB plays a central role in cell growth and differentiation. The aim of this study was to characterize mesenchymal stromal cells (MSCs) that were genetically modified to overexpress PDGF-BB (PDGF-BB-MSCs) in vitro and evaluate their therapeutic effect when injected into the bone tunnel at the time of CD in an in vivo rabbit model of steroid-associated ONFH.

METHODS

In vitro studies: Rabbit MSCs were transduced with a lentivirus vector carrying the human PDGF-BB gene under the control of either the cytomegalovirus (CMV) or phosphoglycerate (PGK) promoter. The proliferative rate, PDGF-BB expression level, and osteogenic differentiation capacity of unmodified MSCs, CMV-PDGF-BB-MSCs, and PGK-PDGF-BB-MSCs were assessed. In vivo studies: Twenty-four male New Zealand white rabbits received an intramuscular (IM) injection of methylprednisolone 20 mg/kg. Four weeks later, the rabbits were divided into four groups: the CD group, the hydrogel [HG, (a collagen-alginate mixture)] group, the MSC group, and the PGK-PDGF-BB-MSC group. Eight weeks later, the rabbits were sacrificed, their femurs were harvested, and microCT, mechanical testing, and histological analyses were performed.

RESULTS

In vitro studies: PGK-PDGF-BB-MSCs proliferated more rapidly than unmodified MSCs (P < 0.001) and CMV-PDGF-BB-MSCs (P < 0.05) at days 3 and 7. CMV-PDGF-BB-MSCs demonstrated greater PDGF-BB expression than PGK-PDGF-BB-MSCs (P < 0.01). However, PGK-PDGF-BB-MSCs exhibited greater alkaline phosphatase staining at 14 days (P < 0.01), and osteogenic differentiation at 28 days (P = 0.07) than CMV-PDGF-BB-MSCs. In vivo: The PGK-PDGF-BB-MSC group had a trend towards greater bone mineral density (BMD) than the CD group (P = 0.074). The PGK-PDGF-BB-MSC group demonstrated significantly lower numbers of empty lacunae (P < 0.001), greater osteoclast density (P < 0.01), and greater angiogenesis (P < 0.01) than the other treatment groups.

CONCLUSION

The use of PGK-PDGF-BB-MSCs as an adjunctive treatment with CD may reduce progression of osteonecrosis and enhance bone regeneration and angiogenesis in the treatment of early-stage ONFH.

Nomogram to predict collapse-free survival after core decompression of nontraumatic osteonecrosis of the femoral head

Background

Nontraumatic osteonecrosis of the femoral head (NONFH) is a devastating disease, and the risk factors associated with progression into collapse after core decompression (CD) remain poorly defined. Therefore, we aim to define risk factors associated with collapse-free survival (CFS) after CD of precollapse NONFH and to propose a nomogram for individual risk prediction.

Methods

According to the baseline characteristics, clinical information, radiographic evaluations, and laboratory examination, a nomogram was developed using a single institutional cohort of patients who received multiple drilling for precollapse NONFH between January 2007 and December 2019 to predict CFS after CD of precollapse NONFH. Furthermore, we used C statistics, calibration plot, and Kaplan-Meier curve to test the discriminative ability and calibration of the nomogram to predict CFS.

Results

One hundred and seventy-three patients who underwent CD for precollapse NONFH were retrospectively screened and included in the present study. Using a multiple Cox regression to identify relevant risk factors, the following risk factors were incorporated in the prediction of CFS: acute onset of symptom (HR, 2.78; 95% CI, 1.03–7.48; P = 0.043), necrotic location of Japanese Investigation Committee (JIC) C1 and C2 (HR, 3.67; 95% CI, 1.20–11.27; P = 0.023), necrotic angle in the range of 250–299°(HR, 5.08; 95% CI, 1.73–14.93; P = 0.003) and > 299° (HR, 9.96; 95% CI, 3.23–30.70; P < 0.001), and bone marrow edema (BME) before CD (HR, 2.03; 95% CI, 1.02-4.02; P = 0.042). The C statistics was 0.82 for CFS which revealed good discriminative ability and calibration of the nomogram.

Conclusions

Independent predictors of progression into collapse after CD for precollapse NONFH were identified to develop a nomogram predicting CFS. In addition, the nomogram could divide precollapse NONFH patients into prognosis groups and performed well in internal validation.

The efficacy of core decompression for steroid-associated osteonecrosis of the femoral head in rabbits

Although core decompression (CD) is often performed in the early stage of osteonecrosis of the femoral head (ONFH), the procedure does not always prevent subsequent deterioration and the effects of CD are not fully clarified. The aim of this study is to evaluate the efficacy of CD for steroid-associated ONFH in rabbits. Twelve male and 12 female New Zealand rabbits were injected intramuscularly 20 mg/kg of methylprednisolone once and were divided into the disease control and CD groups. In the disease control group, rabbits had no treatment and were euthanized at 12 weeks postinjection. In the CD group, rabbits underwent left femoral CD at 4 weeks postinjection and were euthanized 8 weeks postoperatively. The left femurs were collected to perform morphological, biomechanical, and histological analysis. Bone mineral density and bone volume fraction in the femoral head in the CD group were significantly higher than in the disease control group. However, no difference in the mechanical strength was observed between the two groups. Histological analysis showed that alkaline phosphatase and CD31 positive cells significantly increased in the males after CD treatment. The number of empty lacunae in the surrounding trabecular bone was significantly higher in the CD group. The current study indicated that CD improved the morphological properties, but did not improve the mechanical strength in the femoral head at early-stage ONFH. These data suggest the need for additional biological, mechanical strategies, and therapeutic windows to improve the outcome of early-stage steroid-associated ONFH.

The efficacy of lapine preconditioned or genetically modified IL4 over-expressing bone marrow-derived mesenchymal stromal cells in corticosteroid-associated osteonecrosis of the femoral head in rabbits

Cell-based therapy for augmentation of core decompression (CD) using mesenchymal stromal cells (MSCs) is a promising treatment for early stage osteonecrosis of the femoral head (ONFH). Recently, the therapeutic potential for immunomodulation of osteogenesis using preconditioned (with pro-inflammatory cytokines) MSCs (pMSCs), or by the timely resolution of inflammation using MSCs that over-express anti-inflammatory cytokines has been described. Here, pMSCs exposed to tumor necrosis factor-alpha and lipopolysaccharide for 3 days accelerated osteogenic differentiation in vitro. Furthermore, injection of pMSCs encapsulated with injectable hydrogels into the bone tunnel facilitated angiogenesis and osteogenesis in the femoral head in vivo, using rabbit bone marrow-derived MSCs and a model of corticosteroid-associated ONFH in rabbits. In contrast, in vitro and in vivo studies demonstrated that genetically-modified MSCs that over-express IL4 (IL4-MSCs), established by using a lentiviral vector carrying the rabbit IL4 gene under the cytomegalovirus promoter, accelerated proliferation of MSCs and decreased the percentage of empty lacunae in the femoral head. Therefore, adjunctive cell-based therapy of CD using pMSCs and IL4-MSCs may hold promise to heal osteonecrotic lesions in the early stage ONFH. These interventions must be applied in a temporally sensitive fashion, without interfering with the mandatory acute inflammatory phase of bone healing.

Is bone marrow edema syndrome a precursor of hip or knee osteonecrosis? Results of 49 patients and review of the literature

PURPOSE

Diagnosis of bone marrow edema syndrome (BMES) can be challenging. There is sometimes uncertainty about the correct diagnosis of BMES on morphologic magnetic resonance imaging (MRI), since subchondral findings like lines and spots can be misinterpreted as "beginning" or "possible" avascular osteonecrosis (AVN). The aim of our study was to systematically assess the temporal course of BMES from first diagnosis on MRI until the end of clinical symptoms and the full disappearance of bone marrow edema (BME) to determine whether subchondral lines and spots detected in these patients can develop into osteonecrosis.

METHODS

In a combined retrospective and prospective study, we retrieved serial MRI scans of hips and knees with BME from the hospital database. According to clinical and imaging data, all patients with degenerative, infectious/inflammatory, rheumatic, neoplastic conditions and those showing typical osteonecrosis were excluded. We collected all available MRI examinations from first detection of BME until its disappearance. In case edema had not fully resolved in the last available MRI scan, we performed an MRI with an additional dynamic contrast-enhanced (DCE-MRI) sequence. For each MRI scan, we recorded the severity of edema, the presence of subchondral hypointense lines and the presence of subchondral focal hypointense zones on T1-weighted images by two independent readers. The DCE-MRI scans were used to calculate parameter maps to assess the perfusion characteristics.

RESULTS

The study comprised 49 patients aged 22-71 years. In total, 171 morphologic and 5 DCE-MRI scans were evaluated. In 44 patients (89.8%), the BMES completely healed without remnants. In 18 of 49 patients (36.7%), a subchondral line was present in the first MRI exam. Nine patients (18.4%) developed a subchondral line within 1-5 months after the first MRI. In total, 27 out of 49 patients (55.1%) had subchondral lines (12 knees, 15 hips) during the timeframe of the study. All subchondral lines disappeared in the timeframe of the study. Subchondral focal hypointense zones were present in 14 out of 49 patients (28.6%): in 9 cases, subchondral focal hypointense zones disappeared after a median of 5.5 months (range, 1-85 months), while in 5 cases, subchondral focal lesions persisted until the end of the study (up to more than 85 months) without edema in the surrounding bone. All persisting subchondral focal lesions were hyperperfused. These 5 patients had associated meniscal lesions.

CONCLUSION

Our study shows that subchondral lines and spots found in patients with BMES do not develop into AVN. Subchondral lines, which resemble subchondral insufficiency fractures, are associated with BMES. Subchondral focal T1-hypointense zones do not represent AVN; most probably these areas represent reparative processes within the subchondral bone, where tensile and shear force overload is present due to altered biomechanics.

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.

Japanese Orthopaedic Association 2019 Guidelines for osteonecrosis of the femoral head

PURPOSE

The Clinical Practice Guidelines for Osteonecrosis of the Femoral Head (ONFH) 2019 Edition, written by the working group for ONFH guidelines of the Japanese Investigation Committee (JIC) for ONFH under the auspices of the Japanese Ministry of Health, Labour, and Welfare and endorsed by the Japanese Orthopaedic Association, were published in Japanese in October 2019. The objective of this guideline is to provide a support tool for decision-making between doctors and patients.

METHODS

Procedures for developing this guideline were based on the Medical Information Network Distribution Service Handbook for Clinical Practice Guideline Development 2014, which proposed an appropriate method for preparing clinical guidelines in Japan.

RESULTS

This clinical practice guideline consists of 7 chapters: epidemiology; pathology; diagnosis; conservative therapy; surgical treatment: bone transplantation/cell therapy; surgical treatment: osteotomy; and surgical treatment: hip replacement. Twelve background questions and 13 clinical questions were determined to define the basic features of the disease and to be addressed when deciding treatment in daily practice, respectively.

CONCLUSIONS

The clinical practice guidelines for the ONFH 2019 edition will be useful for physicians, investigators, and medical staff in clinical practice, as well as for patients, during the decision-making process when defining how to treat ONFH.

Disassembly of bilateral bipolar heads within 10 years after hip hemiarthroplasties for avascular necrosis of femoral heads: a case report

Prosthetic joint surgeries, total hip arthroplasty (THA) or bipolar hemiarthroplasty (BHA) and joint preservation surgeries can be performed for avascular osteonecrosis of femoral head (ONFH) with collapse. Although excellent surgical results have been reported, long-term survivorship and postoperative complications are a great concern. The purpose of this study was to report a case of bilateral disassembly of bipolar heads within 10 years after BHA for ONFH. A 61-year-old man, whose occupation was carpenter, underwent bilateral BHA for ONFH at another hospital when he was 57 years old. He had acute right hip pain during working and visited our institute. Radiographs revealed intra-articular (outer and inner head) disassembly of the right bipolar head, and conversion to THA was performed. Five years later, he had contralateral (left) hip pain. Radiographs revealed disassembly of bipolar head, as had occurred with the right hip, and similar conversion surgery was performed for the left hip. Marked wear and detachment of the polyethylene bearings of the outer head and failure of the locking mechanism between a skirted 22-mm-diameter inner head and polyethylene insert were observed in both hips at each revision surgery. Degeneration of the acetabulum were also observed in both hips. The failure of the self-centering mechanism because of degenerative change of the acetabulum, impingement of the outer head and neck, and high activity seemed to be the causes of disassembly of the bilateral bipolar heads. Therefore, it is important to select the type of prostheses depending on the age, activity and occupation of each patient.

Incidence and risk factors for osteonecrosis of the hip in renal transplant patients: a prospective single-centre study

BACKGROUND

There is a lack of evidence about the risk factors associated with osteonecrosis of the femoral head (ONFH).

PURPOSES

To determine the incidence and risk factors for ONFH following renal transplantation (RT).

METHODS

In total, data of 681 RT patients (mean age at surgery, 49.5 ± 13.6 years; 249 women and 432 men) were evaluated to determine the incidence of ONFH. Hip magnetic resonance imaging (MRI) was performed six months after RT. The following potential predictors of ONFH were evaluated: (1) patient's condition at RT; laboratory test results including calcium (Ca), phosphorus (P), calcium-phosphorus product (Ca × P), and intact parathyroid hormone before RT; blood relationship between the patient and donor; and mismatching number of human leukocyte antigens (HLAs), especially HLA class I and class II and (2) dosages of steroids after RT, immunosuppressive regimen, and incidence of acute rejection.

RESULTS

ONFH was observed in 30 hips (21 cases, 3.1%). We successfully matched 63 patients without ONFH. Multivariate logistic regression analysis, adjusted for cumulative dosages of steroids, revealed that mismatching number of HLA (hazard ratio [HR], 1.61; 95% confidence interval [CI], 1.10-2.36; p = 0.014), HLA class II (HR, 3.73; 95% CI, 1.46-9.56; p = 0.001), P before RT (HR, 1.62; 95% CI, 1.02-2.58; p = 0.041), and Ca × P  before RT (HR, 1.06; 95% CI, 1.01-1.11; p = 0.024) were risk factors for ONFH.

CONCLUSION

A greater number of HLA mismatches, HLA class II, serum P, and serum Ca × P were risk factors for ONFH after RT. Therefore, these factors should be evaluated in order to predict ONFH after RT.

Transitional changes in the incidence of hip osteonecrosis among renal transplant recipients

BACKGROUND

Immunosuppressive therapy for renal allograft recipients has changed substantially since the introduction of the anti-CD25 monoclonal antibody, basiliximab. We hypothesized that recent improvements in immunosuppressive treatment may reduce the incidence of osteonecrosis of the femoral head (ONFH). This study aimed to investigate transitional changes in the incidence of OFNH among renal transplant recipients by MRI.

METHODS

Participants comprised 110 patients who had undergone renal transplantation from 2003 to 2012, during which time basiliximab was in regular use at our institute (Recent group), and 232 patients who had undergone RT between 1986 and 2003 (Past group). We compared ONFH incidence between the two groups and evaluated risk factors for ONFH, including immunosuppressants (calcineurin inhibitors, basiliximab, and/or steroids) and postoperative renal function.

RESULTS

Incidence of ONFH was lower in the Recent group (0%) than in the Past group (3.4%; p = 0.043). In the Recent group, age was greater, ABO/human leukocyte antigen incompatibility was worse, while steroid dose was decreased and post-transplant renal function was improved. Cumulative methylprednisolone dose at postoperative week 2 and delayed graft function were identified as risk factors for ONFH.

CONCLUSION

Risk of ONFH after renal transplantation has fallen with the advent of regular use of basiliximab, although this agent does not appear to be a factor directly associated with the incidence of ONFH.

STUDY DESIGN

Clinical prognostic study (Level III case control study).

How We Manage Bone Marrow Edema-An Interdisciplinary Approach

Bone marrow edema (BME) is a descriptive term for a common finding in magnetic resonance imaging (MRI). Although pain is the major symptom, BME differs in terms of its causal mechanisms, underlying disease, as well as treatment and prognosis. This complexity together with the lack of evidence-based guidelines, frequently makes the identification of underlying conditions and its management a major challenge. Unnecessary multiple consultations and delays in diagnosis as well as therapy indicate a need for interdisciplinary clinical recommendations. Therefore, an interdisciplinary task force was set up within our large osteology center consisting of specialists from internal medicine, endocrinology/diabetology, hematology/oncology, orthopedics, pediatrics, physical medicine, radiology, rheumatology, and trauma surgery to develop a consenus paper. After review of literature, review of practical experiences (expert opinion), and determination of consensus findings, an overview and an algorithm were developed with concise summaries of relevant aspects of the respective underlying disease including diagnostic measures, clinical features, differential diagnosis and treatment of BME. Together, our single-center consensus review on the management of BME may help improve the quality of care for these patients.

[Imaging and classification of avascular femoral head necrosis]

Avascular femoral head necrosis (AVNFH) is difficult to diagnose on plain radiographs in early stages of the disease. Since early stages are often clinically occult, early use of MRI is required to rule out or verify a clinical suspicion. MRI and, in some cases, additional CT are the cornerstones of AVNFH diagnosis and classification. Anteroposterior radiography of the pelvis and a second plane of the involved hip remains the primary basic imaging examination for follow-up and to rule out other pathologies. Correct staging of adult disease has been shown to be the key factor in therapeutic decision-making. According to the German S3 guideline on diagnosis and treatment of AVNFH, use of the ARCO classification is recommended for staging. This paper presents the current status of diagnosis and classification of adult AVNFH. The criteria for ascribing disease to a particular ARCO stage are defined and critically discussed.

Magnetic resonance imaging of subchondral insufficiency fractures of the lower limb

Subchondral insufficiency fracture (SIF) is a non-traumatic condition that has historically been associated with elderly, osteoporotic women and patients with systemic conditions. There has been much work done to determine the pathogenesis of SIF, which has previously been regarded as idiopathic, rapid-progressive osteoarthritis or osteonecrosis of the hip, spontaneous osteonecrosis of the knee (SONK), osteochondral defect (OCD) of the talus and adult-onset Freiberg infraction of the metatarsal head. Early diagnosis and management are crucial to prevent subchondral collapse, secondary osteonecrosis and early-onset osteoarthritis. Magnetic resonance imaging (MRI) plays an important role in the diagnosis of SIF, which is often inconspicuous on initial radiographs. In this article, the authors provide an update on the role of MRI in identifying key imaging features of SIF in various joints of the lower limb to aid in its correct diagnosis.

Incidence of osteonecrosis and insufficiency fracture of the hip and knee joints based on MRI in 300 renal transplant patients

INTRODUCTION

The purpose of this study was to investigate the incidence of necrosis and insufficiency fracture of the hip and knee using magnetic resonance imaging (MRI) in renal transplant patients.

METHODS

We examined 300 consecutive renal transplant patients using MRI of the hips and knees (T1-weighted coronal MRI) preoperatively and at 3 and 6 months postoperatively. Oblique axial-plane T1-weighted MRI and short-tau inversion-recovery T2-weighted MRI were performed parallel to the femoral neck when distinguishing the osteonecrosis of the femoral head (ONFH) from subchondral insufficiency fracture (SIF) of the femoral head was difficult.

RESULTS

ONFH was observed in 3 hips (3 cases, 1.0%). Osteonecrosis of the knee was observed in 2 knees (1 case, 0.3%). SIF of the femoral head was observed in 5 hips (3 cases, 1.0%). Bilateral simultaneous onset of SIF of the femoral head was observed in 2 cases (0.7%). Insufficiency fracture of the knee was observed in 2 knees (1 case, 0.3%).

CONCLUSIONS

When it was difficult to distinguish ONFH from SIF of the femoral head, oblique axial-plane T1-weighted MRI and the short-tau inversion-recovery T2-weighted MRI parallel to the femoral neck were useful to establish the correct diagnosis.

The effects of a functionally-graded scaffold and bone marrow-derived mononuclear cells on steroid-induced femoral head osteonecrosis

Osteonecrosis of the femoral head (ONFH) is a debilitating disease that may progress to femoral head collapse and subsequently, degenerative arthritis. Although injection of bone marrow-derived mononuclear cells (BMMCs) is often performed with core decompression (CD) in the early stage of ONFH, these treatments are not always effective in prevention of disease progression and femoral head collapse. We previously described a novel 3D printed, customized functionally-graded scaffold (FGS) that improved bone growth in the femoral head after CD in a normal healthy rabbit, by providing structural and mechanical guidance. The present study demonstrates similar results of the FGS in a rabbit steroid-induced osteonecrosis model. Furthermore, the injection of BMMCs into the CD decreased the osteonecrotic area in the femoral head. Thus, the combination of FGS and BMMC provides a new therapy modality that may improve the outcome of CD for early stage of ONFH by providing both enhanced biological and biomechanical cues to promote bone regeneration in the osteonecrotic area.

Bilateral osteonecrosis of the femoral head associated with corticosteroid therapy for alopecia areata: a case report and review of the literature

Corticosteroids have been widely used for the treatment of various inflammatory diseases because they provide an acute response of immunosuppression. Numerous side effects of corticosteroids have also been known, with varying degrees of severity. Osteonecrosis of the femoral head (ONFH) is a rare and serious complication that directly inhibits walking because of femoral head collapse. However, sometimes, clinicians who consider that corticosteroids are required for primary disease do not recognize steroid-induced ONFH. The final stage of ONFH is severe osteoarthritis, requiring total hip arthroplasty. We describe a 23-year-old woman with bilateral ONFH after corticosteroid treatment for alopecia areata (AA). She was administered several intralesional corticosteroid injections to the scalp and repeated systemic corticosteroid therapy for extensive AA. While undergoing therapy, she lost her balance and complained of right groin pain when standing. The patient was subsequently diagnosed with bilateral ONFH. She recovered from AA, but she complained of persistent right hip pain, which subsequently required total hip arthroplasty. We would like to emphasize that patients on corticosteroid therapy for any common disease should be considered as having a potential risk for ONFH. An early stage detection of ONFH is crucial for its treatment. MRI evaluation warrants a higher level of accuracy in early diagnosis of ONFH for the opportunity to undergo joint-preservation surgery in patients with ONFH.

Which Classification System Is Most Useful for Classifying Osteonecrosis of the Femoral Head?

BACKGROUND

Many studies have confirmed that the size and location of necrotic lesions are major factors that affect the prevalence of collapse and prognosis in patients with osteonecrosis of the femoral head (ONFH). Although several classification systems categorize and quantify ONFH, there is no agreement on which one is most useful for the purpose.

QUESTIONS/PURPOSES

We compared the Steinberg, modified Kerboul, and Japanese Investigation Committee (JIC) classifications of ONFH in terms of (1) the correlation among the three different classification systems. We further examined (2) the inter- and intraobserver reliability of the three classification systems and (3) the association of higher grades within each classification and the risk of subsequent collapse.

METHODS

Between January 2000 and December 2014, we treated 101 hips in 74 patients for precollapse ONFH, diagnosed either on plain radiographs or MRI. Of those, one patient (1%) died, six patients (8%) were lost to followup, and two patients (3%) underwent osteotomy before 2 years, leaving 86 hips in 65 patients (88%) for analysis here. Three-dimensional spoiled gradient-echo sequence (3D-SPGR) MRI was performed for all hips, and the presence of ONFH was determined by finding the area surrounded by the outer margin of the low-signal-intensity band on 3D-SPGR MRI. Patients with ONFH were categorized using the Steinberg, modified Kerboul, and JIC classification systems, and correlations among these three classification systems were investigated. Inter- and intraobserver reliability was assessed by 10 orthopaedic surgeons using 40 sets of 3D-SPGR MR images. The reliability of each system was evaluated using the kappa coefficient. The cumulative survival rate with collapse and undergoing hip arthroplasty as the endpoints was evaluated for each of the three classification systems (mean followup, 9 years; range, 2-16 years), and the association of higher grades within each classification and the risk of subsequent collapse were also evaluated.

RESULTS

We found strong correlations between the Steinberg and modified Kerboul classifications (ρ = 0.83, p < 0.001), the Steinberg and JIC classifications (ρ = 0.77, p < 0.001), and the modified Kerboul and JIC classifications (ρ = 0.80, p < 0.001). Interobserver reliability in the JIC classification (0.72; range, 0.30-0.90) was higher than that in the Steinberg classification (0.56; range, 0.24-0.84; p < 0.001) and the modified Kerboul classification (0.57; range, 0.35-0.80; p < 0.001). The cumulative survival rate with collapse as the endpoint after a minimum of 2 years of followup in the Steinberg classification differed between Grades A (82%; 95% confidence interval [CI], 66%-97%) and B (43%; 95% CI, 21.9%-64.8%; p = 0.007), Grades A and C (20%; 95% CI, 4.3%-35.7%; p < 0.001), and Grades B and C (p = 0.029). Survival was lower for modified Kerboul Grade 4 hips (12%; 95% CI, 0%-27.1%) than for Steinberg Grade C hips (20%; 95% CI, 4.3%-35.7%) and JIC Type C2 hips (18%; 95% CI, 2.8%-34.0%). The JIC classification was best able to identify hips at low risk of collapse because no JIC Type A hips collapsed.

CONCLUSIONS

The JIC classification was more reliable and effective, at least for early-stage ONFH, than the Steinberg or modified Kerboul classifications. Further investigation might be useful to identify whether each classification system emphasizes specific risk factors for collapse.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Clinical analysis of 23 cases of steroid-associated osteonecrosis of the femoral head with normal initial magnetic resonance imaging presentation

To explore the clinical characteristics of steroid-associated osteonecrosis of the femoral head (ONFH) presenting initially normal magnetic resonance imaging (MRI) results.This retrospective study examined data from 23 cases that suffered from ONFH but presented a normal image at the first MRI examination after corticosteroid therapy from June 2005 to December 2013. Data on protopathy, age, sex, time of pain onset, MRI examination, and initial diagnosis were collected and analyzed.Average time from steroid therapy to first MRI examination was 45.7 ± 25.5 days (range, 10-94 days). Average time to final diagnosis was 199.9 ± 165.8 days (range, 32-762 days). Of the 23 cases, 21 cases complained of discomfort and were misdiagnosed because of a normal initial MRI scan. Twelve hips progressed to collapse and 1 hip received lumbar discectomy when got the final diagnosis. Cases with continuous pain (9/21) presented with pain at a later time than those with intermittent pain (12/21), although the continuous pain cases were diagnosed earlier.MRI performed 2 to 3 months after steroid therapy may present normal images. Another MRI examination is necessary to make a definite diagnosis.

[Posttherapeutic changes in bone marrow]

The bone marrow basically consists of red blood-forming bone marrow and yellow fat. In the skeleton, there is an age-dependent distribution of these two parts. In the context of medical interventions or therapies, bone marrow changes can occur, whereby the normal bone marrow can basically be replaced by fat, edema, or fibrosis/sclerosis. Here, specific signal intensities and patterns are shown in imaging. After irradiation therapies, edematous changes, hemorrhages, and osteoradionecroses are observed. Likewise, insufficiency fractures, impairment of the growth gaps, or the development of tumors is possible. In patients on dialysis, deposit of protein in the bone marrow is possible in the case of the so-called amyloidosis osteoarthropathy. Postoperative bone marrow edema, insufficiency fractures, or osteonecrosis can be observed after arthroscopy. Changes in the distribution of fat markers and blood-forming bone marrow can be observed after stem cell transplants. In the therapy with cortisone, insufficiency fractures and osteonecroses are possible. Depending on their effect on the hematopoietic system, chemotherapyies can first lead to edematous changes and then to fatty bone marrow, which is reversible after therapy. Angiogenesis inhibitors in combination with other chemotherapeutic agents often lead to mixed images of stimulated and fatty bone marrow.

Hip preserving surgery with concentrated autologous bone marrow aspirate transplantation for the treatment of asymptomatic osteonecrosis of the femoral head: retrospective review of clinical and radiological outcomes at 6 years postoperatively

Background

We had previously established concentrated autologous bone marrow aspirate transplantation (CABMAT), a one-step, low-invasive, joint-preserving surgical technique for treating osteonecrosis of the femoral head (ONFH). The present study aimed to evaluate the effects of CABMAT as a hip preserving surgical approach, preventing femoral head collapse in asymptomatic ONFH.

Methods

In total, 222 patients (341 hips) with ONFH were treated with CABMAT between April 2003 and March 2013. Based on magnetic resonance imaging, we determined that 119 of these patients had bilateral asymptomatic ONFH (238 hips), and 38 further patients had unilateral asymptomatic ONFH (38 hips). In this series, we retrospectively examined 31 hips in 31 patients with unilateral asymptomatic ONFH treated surgically between 2003 and 2012 and followed up for more than 2 years. Clinical and radiological evaluation were performed immediately before the procedure and at the final follow-up. The two-year follow-up rate among patients with unilateral ONFH was 82% (31/38). Therefore, the present study included 31 patients (19 males and 12 females), with a mean age and follow-up period of 40 and 5.8 years, respectively. Of the 31 asymptomatic hips, 5, 6, 10, and 10 had osteonecrosis of types A, B, C1, and C2, respectively. The diagnosis, classification, and staging of ONFH were based on the 2001 Japanese Orthopaedic Association (JOA) classification.

Results

Secondary collapse of the femoral head was observed in 6/10 hips and 5/10 hips with osteonecrosis of types C1 and C2, respectively. Total hip arthroplasty was performed in 9.6% of patients (3/31 hips), at an average of 33 months after surgery. Clinical symptoms improved after surgery, and the secondary collapse rate at a mean of 5.8 years after CABMAT was lower than that reported in several previous studies on the natural course of asymptomatic ONFH.

Conclusions

Early diagnosis of ONFH (i.e., before femoral head collapse) and early intervention with CABMAT could improve the clinical outcome of corticosteroid and alcohol-induced ONFH.

Favorable Clinical and Radiographic Results of Transtrochanteric Anterior Rotational Osteotomy for Collapsed Subchondral Insufficiency Fracture of the Femoral Head in Young Adults

Background:

Subchondral insufficiency fracture of the femoral head (SIF) occurs infrequently in young adults. As the collapsed SIF lesion is usually located at the anterior portion of the femoral head, young adults with SIF are considered to be candidates for transtrochanteric anterior rotational osteotomy, similar to patients with osteonecrosis of the femoral head (ON). In the present study, we assessed the clinical and radiographic results of anterior rotational osteotomy for the treatment of SIF as compared with ON.

Methods:

We retrospectively reviewed 28 consecutive patients who underwent anterior rotational osteotomy for the treatment of unilateral SIF (7 patients) or unilateral ON (21 patients). The mean duration of follow-up was 3.7 years (range, 2.0 to 6.2 years). Clinical and radiographic assessments were performed with use of the Harris hip score (HHS), sequential radiographs, and single-photon emission computed tomography/computed tomography (SPECT/CT) with ^99mTc-hydroxymethylene diphosphonate performed 5 weeks after surgery.

Results:

The mean HHS (and standard deviation) in the SIF group improved significantly from 51.6 ± 11.7 preoperatively to 91.9 ± 7.1 at 1 year after surgery and to 96.9 ± 3.8 at the time of the latest follow-up (p = 0.0010 and 0.0002, respectively). Similarly, the mean HHS in the ON group improved significantly from 52.4 ± 13.7 preoperatively to 80.7 ± 10.0 at 1 year after surgery and to 88.2 ± 12.6 at the time of the latest follow-up (p < 0.0001 for both). The HHS was significantly higher in the SIF group than in the ON group at 1 year after surgery (p = 0.019), but there was no significant difference between the groups at the time of the latest follow-up (p = 0.10). A postoperative intact ratio (calculated as the intact area of the femoral head divided by the weight-bearing area of the acetabulum on an anteroposterior radiograph) of >80% was achieved in association with smaller femoral neck-shaft varus angles in the SIF group (10.0° ± 4.2°) as compared with the ON group (15.3° ± 8.2°). Postoperative progression of collapse at the anteriorly rotated subchondral lesion was observed in 5 patients (23.8%) in the ON group but no patients in the SIF group. SPECT/CT images showed that rate of increased tracer uptake at the collapsed lesions in the SIF group was significantly higher than that in the ON group (p < 0.0001).

Conclusions:

The present study suggested that the absence of progression of collapse and a sufficient postoperative intact ratio without the need for marked varus realignment may be associated with favorable results following anterior rotational osteotomy for the treatment of SIF in young adults.

Level of Evidence:

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Radiologic and Clinical Features of Misdiagnosed Idiopathic Osteonecrosis of the Femoral Head

Idiopathic osteonecrosis of the femoral head (ONFH) can be correctly diagnosed in accordance with the established criteria. However, some general orthopedic physicians have misdiagnosed patients as having ONFH. The goal of this study was to clarify the radiologic and clinical features of misdiagnosed patients. This study included 50 patients who were referred to the authors' hospital by general physicians with a diagnosis of ONFH. The correct diagnosis was made based on the Japanese Investigation Committee diagnostic criteria for ONFH. Demographic data were compared between patients with and without ONFH. Of the 50 patients, 24 were diagnosed with other diseases: 10 with osteoarthritis, 7 with transient osteoporosis of the femoral head, 4 with rapidly destructive coxopathy, and 3 with subchondral insufficiency fracture. Seventeen patients who did not have ONFH had magnetic resonance imaging findings that showed a bone marrow edema pattern at the femoral head. The mean age of 62.9 years among patients without ONFH was significantly higher than that of 45.2 years among patients with ONFH. There were 18 female patients in the non-ONFH group and 5 female patients in the ONFH group. Bilateral disease was found in 1 patient in the non-ONFH group and 17 patients in the ONFH group. No patients in the non-ONFH group had a history of systemic steroid administration compared with 11 patients in the ONFH group. Clinical features associated with the non-ONFH group were female sex, older age, unilateral disease, and no history of systemic steroid administration. For patients with these features, the diagnosis of ONFH should be made carefully. [Orthopedics. 2017; 40(1):e117-e123.].

Transient Bone Marrow Edema Syndrome versus Osteonecrosis: Perfusion Patterns at Dynamic Contrast-enhanced MR Imaging with High Temporal Resolution Can Allow Differentiation

Purpose To prospectively evaluate the perfusion patterns at quantitative dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging of transient bone marrow edema syndrome (TBMES) and avascular osteonecrosis. Materials and Methods Institutional review board approval and written informed consent were obtained. Thirty-two patients (21 men, 11 women; mean age, 48 years; 26 hips, 10 knees) underwent conventional MR imaging and a dynamic contrast-enhanced three-dimensional spoiled gradient-echo sequence at 3 T. Parameter maps for mean transit time (MTT) and plasma flow (PF) were evaluated qualitatively and quantitatively. Differences in perfusion patterns were analyzed by using the Fisher exact test. Regions of interest were drawn in areas of high PF and long MTT on each parametric map. Mean, median, standard deviation, minimum, and maximum values were determined. TBMES and osteonecrosis were compared statistically by using the Mann-Whitney U and Wilcoxon signed-rank tests, with a P value of less than .05 considered indicative of a significant difference. Results Nineteen joints with TBMES and 17 joints with osteonecrosis were evaluated. TBMES joints showed a subchondral elongated area of high PF and low MTT that was surrounded by an area of long MTT and low PF. Osteonecrosis joints showed a subchondral area with low or no detectable PF and MTT adjacent to the joint surface, which was surrounded by a rim of high PF and intermediate MTT. Patterns for TBMES and osteonecrosis did not overlap. A significant difference (P < .001) in PF in the immediate subchondral area was found between TBMES and osteonecrosis; in joints with osteonecrosis, this was comparable to background noise, and therefore, could not be quantified. In the circumscribed rim of high PF and intermediate MTT, which was only found in joints with osteonecrosis, mean ± standard deviation PF was 18.9 mL/100 mL per minute ± 11.0 and mean MTT was 213.3 seconds ± 56.8. No significant difference between TBMES and osteonecrosis was found for MTT (P = .09) and PF (P = .75) in the surrounding area. Conclusion Parameter maps derived at dynamic contrast-enhanced MR imaging with high temporal resolution can allow differentiation of osteonecrosis from TBMES in hip and knee joints. ^© RSNA, 2016 Online supplemental material is available for this article.

Fat-suppressed T2-weighted MRI appearance of subchondral insufficiency fracture of the femoral head

OBJECTIVE

Our aims were to investigate the imaging appearance of subchondral insufficiency fracture (SIF) of the femoral head based on fat-suppressed T2-weighted MRI, and evaluate its correlation with the clinical outcomes following conservative treatment.

MATERIALS AND METHODS

We retrospectively evaluated 40 hips in 37 patients with SIF of the femoral head (12 males and 25 females; mean age 55.8 years, range 22-78 years). MRI examinations were performed within 3 months after the onset of hip pain. Using fat-suppressed T2-weighted imaging, we evaluated the hips for the intensity of the subchondral bone (corresponding to the area superior to the low intensity band on T1-weighted images) as well as bone marrow edema, joint effusion, and presence of the band lesion. We then correlated the intensity of the subchondral bone with clinical outcomes.

RESULTS

The hips were classified into three types based on subchondral intensity on fat-suppressed T2-weighted images: type 1 (21 hips) showed high intensity, type 2 (eight hips) showed heterogeneous intensity, and type 3 (11 hips) showed low intensity. The mean period between pain onset and MRI examination was significantly longer for type 2 hips than for type 1. Healing rates were 86 % for type 1, 75 % for type 2, and 18 % for type 3.

CONCLUSION

SIF cases were classified into three types based on subchondral intensity on fat-suppressed T2-weighted imaging performed within 3 months after pain onset. Type 3 SIF tended to be intractable to conservative treatment compared to type 1 and type 2.

Clinical and basic research on steroid-induced osteonecrosis of the femoral head in Japan

BACKGROUND

Steroid (glucocorticoid)-induced osteonecrosis of the femoral head (ONFH) in young adults has been a challenging disorder due to frequent incidence of collapse of the femoral head and resulting dysfunction of the hip joint and impairing quality of life. In Japan, the working group on ONFH in the Specific Disease Investigation Committee under auspices of the Japanese Ministry of Health, Labor and Welfare was founded in 1975, clinical and related basic research on ONFH have been continued for more than 40 years.

EPIDEMIOLOGY AND CLINICAL COURSE

A national epidemiologic survey in 2004 estimated that 2200 new patients per year would be diagnosed with ONFH in Japan. ONFH was associated with steroid intake (51%), heavy alcohol intake (31%), both (3%), and neither (15%). The male-to-female ratio was 5:4, and the peak decades of age at definitive diagnosis were the 40s in male patients and the 30s in females. MRI studies revealed that ONFH would have occurred in early phase after start of steroid administration and no expansion of necrotic lesion within the femoral head in spite of continued steroid use. To standardize ONFH diagnosis and treatment strategy, the Committee established validated diagnostic criteria, a radiological staging system, and type categorization.

TREATMENT OPTIONS

Most symptomatic patients with collapse of the femoral head require various surgical procedures. Joint preserving surgery, such as transtrochanteric rotational osteotomy and curved varus osteotomy, should be the treatment choice for young patients with healthy areas without severe collapse of the femoral head.

CLINICAL AND RELATED BASIC RESEARCH

Clinical and basic research has been performed to determine the pathogenesis of steroid-induced ONFH. Low hepatic CYP3A activity has been reported to significantly contribute to the risk of steroid-induced ONFH. Several gene polymorphisms related to steroid metabolism were shown to be associated with the occurrence of ONFH.

Bone SPECT/CT of Femoral Head Subchondral Insufficiency Fracture

Subchondral insufficiency fracture of the femoral head may be confused with osteonecrosis, mainly because of radiological overlap. SPECT/CT with Tc-99 m hydroxymethylene diphosphonate images in 7 patients with subchondral insufficiency fracture were retrospectively reviewed and compared with those from 11 patients with symptomatic early osteonecrosis. In all of the hips with subchondral insufficiency fracture, SPECT/CT showed increased uptake at the subchondral lesions of the femoral head. On the other hand, in all of the hips with osteonecrosis, absence of uptake was confirmed at the subchondral lesions. SPECT/CT may assist in differentiating subchondral insufficiency fracture from osteonecrosis.

Prediction of femoral head collapse in osteonecrosis using 18F-fluoride positron emission tomography

OBJECTIVE

We investigated the usefulness of (18)F-fluoride PET as a predictor of femoral head collapse in patients with osteonecrosis (ON) before radiographic changes occur.

PATIENTS AND METHODS

Sixty-six hips of 42 patients diagnosed with ON of the femoral head were included in this study. We evaluated the relationship between the maximum standardized uptake value (SUV(max)) in (18)F-fluoride PET and the Ficat classification. We evaluated the relationship between SUV(max) and the presence of femoral head collapse on plain radiography at 12 months after (18)F-fluoride PET in 23 hips of 18 patients with Ficat classification stage 1 or 2. A receiver operating characteristic analysis was carried out to calculate the cut-off SUVmax for the prediction of femoral head collapse. We analyzed the relationship between SUV(max) and femoral head collapse on plain radiography in the 23 hips using a logistic regression model.

RESULTS

SUV(max) increased according to the progression of the Ficat classification stage. The mean SUV(max) was 12.3±5.9 in the collapse group and 4.9±1.3 in the noncollapse group (P<0.01). The cut-off SUV(max) of 6.45 (sensitivity: 0.80, specificity: 0.92) was used for the prediction of femoral head collapse. In the univariate analysis, SUV(max), type classification, and ring sign were related significantly to femoral head collapse.

CONCLUSION

We showed that the quantitative assessment of SUV(max) in (18)F-fluoride PET was useful to predict femoral head collapse in ON. (18)F-Fluoride PET might reflect accelerated bone metabolism because of microcollapse of the femoral head, which is undetectable on plain radiography.

Subchondral insufficiency fractures of the femoral head: associated imaging findings and predictors of clinical progression

OBJECTIVES

To characterize the morphology and imaging findings of femoral head subchondral insufficiency fractures (SIF), and to investigate clinical outcomes in relation to imaging findings.

METHODS

Fifty-one patients with hip/pelvis magnetic resonance (MR) images and typical SIF characteristics were identified and reviewed by two radiologists. Thirty-five patients had follow-up documentation allowing assessment of clinical outcome. Subgroup comparisons were performed using regression models adjusted for age and body mass index.

RESULTS

SIF were frequently associated with cartilage loss (35/47, 74.5 %), effusion (33/42, 78.6 %), synovitis (29/44, 66 %), and bone marrow oedema pattern (BMEP) (average cross-sectional area 885.7 ± 730.2 mm(2)). Total hip arthroplasty (THA) was required in 16/35 patients, at an average of 6 months post-MRI. Compared to the THA cohort, the non-THA group had significantly (p < 0.05) smaller overlying cartilage defect size (10 mm vs. 29 mm), smaller band length ratio and fracture diameters, and greater incidence of parallel fracture morphology (p < 0.05). Male gender and increased age were significantly associated with progression, p < 0.05.

CONCLUSIONS

SIF were associated with synovitis, cartilage loss, effusion, and BMEP. Male gender and increased age had a significant association with progression to THA, as did band length ratio, fracture diameter, cartilage defect size, and fracture deformity/morphology.

KEY POINTS

• Femoral head subchondral insufficiency fractures (SIF) frequently require total hip arthroplasty (THA). • SIF frequently coexist with synovitis, cartilage loss, and bone marrow oedema pattern. • SIF cartilage defect size, band length ratio, and fracture diameter/morphology can predict progression risk.

MRI-detected bone marrow changes within 3 weeks after initiation of high-dose corticosteroid therapy: a possible change preceding the subsequent appearance of low-intensity band in femoral head osteonecrosis

Osteonecrosis of the femoral head is considered to occur early during the course of corticosteroid treatment. However, it remains unclear exactly how early it can develop after initiation of corticosteroid treatment. We report a case of osteonecrosis of the femoral head in which abnormal findings were observed on short-tau inversion recovery (STIR) sequence image performed 2 weeks and 4 days after initiation of high-dose corticosteroid therapy. A 45-year-old man with hemophagocytic syndrome was started on prednisolone, with a maximum dose of 40 mg/day. On day 13 after initiation of this corticosteroid therapy, he transiently experienced left hip pain with no apparent cause. STIR sequence image 5 days after the onset of pain revealed high-intensity bone marrow lesions at the femoral neck of both hips. At 3 months after initiation of corticosteroid therapy, T1-weighted magnetic resonance imaging revealed concave-shaped low-intensity bands, which corresponded to the preceding high-intensity lesions on both hips. Because of the subsequent progression to collapse of the left femoral head, he underwent prosthetic replacement surgery. The high-intensity lesions on STIR sequence image indicate the possibility that osteonecrosis can occur within 3 weeks after initiation of high-dose corticosteroid therapy.

Femoral perfusion after pulsed electromagnetic field stimulation in a steroid-induced osteonecrosis model

This study was designed to evaluate femoral perfusion after pulsed electromagnetic field (PEMF) stimulation in a steroid-induced osteonecrosis rabbit model by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Steroid-induced osteonecrosis was produced by single intramuscular injection of methylprednisolone in 15 rabbits. Eight rabbits underwent PEMF stimulation (PEMF group) and seven did not (control group). DCE-MRI was performed before PEMF stimulation, immediately before steroid administration, and 1, 5, 10, and 14 days after steroid administration. Regions of interest were set in the bilateral proximal femora. Enhancement ratio (ER), initial slope (IS), and area under the curve (AUC) were analyzed. ER, IS, and AUC in the control group significantly decreased after steroid administration compared with before administration (P<0.05). In PEMF group, IS significantly decreased; however, ER and AUC showed no significant differences after steroid administration compared with before. ER and IS in PEMF group were higher than in control group until 10th day, and AUC was higher until 5th day after steroid administration (P<0.05). PEMF stimulation restrains the decrease in blood flow after steroid administration.

Epidemiology of nontraumatic osteonecrosis of the femoral head in Japan

OBJECTIVES

To elucidate the epidemiology of nontraumatic osteonecrosis of the femoral head (ONFH), and to estimate the annual incidence rate in Japan.

METHODS

We examined, over the course of 3 years, personal records and radiographic images from the national registry of documents used for the study of nontraumatic ONFH in patients in Aichi Prefecture, Japan (population: 7.4 million). Those patients not meeting the diagnostic criteria according to the Japanese Investigation Committee for nontraumatic ONFH were excluded from this study.

RESULTS

A total of 285 out of the 327 patients who applied for the national registration of nontraumatic ONFH during the 3-year study met the diagnostic criteria for personal records, radiographic images, and magnetic resonance images. Forty-two patients (12.8%) were not considered to have nontraumatic ONFH. The mean age of patients was 50.4 years, and the male-female ratio was 2.1:1. Nontraumatic ONFH was steroid-induced in 135 cases (47.4%), alcohol-associated in 87 cases (30.5%), steroid-induced and alcohol- associated in 14 cases (4.9%), and idiopathic in 49 cases (17.2%).

CONCLUSIONS

The age-adjusted annual incidence of nontraumatic ONFH in Aichi Prefecture was estimated at 138.5 patients.Thus the annual incidence rate in Japan (population 128 million) was 1.91/100,000.

Corticosteroid administration within 2 weeks after renal transplantation affects the incidence of femoral head osteonecrosis

BACKGROUND AND PURPOSE

It has been suggested that avascular osteonecrosis (AVN) of the femoral head occurs early after systemic steroid administration. The purpose of this study was to investigate the risks regarding development of AVN at a very early stage after renal transplantation.

METHODS

The presence or absence of AVN was determined by MRI at 4 weeks, at 6-12 weeks, at 24 weeks, and at 12 months after renal transplantation in 286 patients (183 males) with a mean age of 39 (16-65) years. The relationship between AVN and age, sex, absence or presence of acute rejection (AR), type of transplanted kidney (living or cadaveric), type of immune suppressor, and total dose of orally administered steroids given in the 2-week period after transplantation was investigated.

RESULTS

There were no statistically significant correlations between the development of AVN and age, sex, absence or presence of AR, type of transplanted kidney, or type of immune suppressor. A significant dose-response relationship was found between development of AVN and the total dose of steroid administered in the first 2 weeks after surgery.

INTERPRETATION

We found a relationship between AVN development and steroid dose in the early postoperative period, and we also showed a dose-response relationship.

Imaging and histopathological evaluation of a cystlike formation in subchondral insufficiency fracture of the femoral head: A case report and literature review

INTRODUCTION

In the majority of subchondral insufficiency fractures (SIFs) of the femoral head, T₁-weighted magnetic resonance imaging shows an irregular, serpiginous, low-intensity band that is convex to the articular surface. We report a case of a cystlike formation in SIF of the femoral head in an elderly woman.

PRESENTATION OF CASE

A 71-year-old woman reported right hip pain without any history of antecedent trauma. The initial radiograph showed a slight narrowing of the joint space in the right hip. The patient was treated with conservative therapy for 2 months. Radiographs obtained 3 months after the onset of pain showed non-progressive joint-space narrowing. T₁-weighted magnetic resonance images obtained 2 months after pain onset revealed a round, cystlike, low-intensity area just beneath the articular cartilage. The patient underwent total hip arthroplasty. Histopathological examination showed fracture callus and granulation tissue in the subchondral area, surrounded by vascular-rich granulation tissue and fibrous tissue, which corresponded to the round, low-intensity band observed on the T₁-weighted image.

DISCUSSION

This case was a rare SIF of the femoral head which had a cystlike formation with a low signal intensity on T₁-weighted images and a very high signal intensity on STIR sequences in the superolateral portion of the femoral head, surrounded by a pattern of edema in the bone marrow. To our knowledge, no similar cases were cited in the literature.

CONCLUSION

It is important for surgeons to keep in mind that sometimes SIFs of the femoral head can appear as a round cystlike formation.

Evaluation of femoral perfusion in a rabbit model of steroid-induced osteonecrosis by dynamic contrast-enhanced MRI with a high magnetic field MRI system

PURPOSE

To evaluate perfusion during the early phase after steroid administration in vivo using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with a high magnetic field MRI system. The main pathogenesis of steroid-induced osteonecrosis is considered to be ischemia.

MATERIALS AND METHODS

A single dose of methylprednisolone (MPSL) was injected into nine rabbits. DCE-MRI was performed for these rabbits before MPSL administration and 1, 5, 10, and 14 days after administration. Time-signal intensity curves were created for each femur based on the signal intensity to evaluate perfusion. Enhancement ratio (ER), initial slope (IS), and area under the curve (AUC) were calculated and the value before MPSL administration and the minimal value after administration were compared statistically.

RESULTS

ER, IS, and AUC values after MPSL administration significantly decreased (P < 0.05, P < 0.01, and P < 0.01, respectively). All of them decreased by the 5th day in 56% of the femora and by the 14th day in 83%, and some femora even showed a decrease from the 1st day.

CONCLUSION

In this study, decreased perfusion in the femora after steroid administration was proven. Additionally, we could show that it occurred from the early days after steroid administration.