Bone marrow edema syndromes of the hip: MRI features in different hip disorders

Detection of bone marrow edema in differential diagnoses of odontogenic cysts using dual-energy computed tomography

PURPOSE

In this study, we prospectively investigated the relationship between bone marrow edema (BME) and odontogenic cysts and explored the possibility of using dual-energy computed tomography (DECT) as an auxiliary tool for the diagnosis of odontogenic cysts.

METHODS

This cross-sectional study included 73 patients who underwent the DECT scan and surgery for odontogenic cysts or odontogenic tumors. The virtual noncalcium (VNCa) computed tomography (CT) values and CT values were measured at several sites. The predictor variable was diagnosis, and the other variables included age, sex, and sites. The primary outcome was VNCa CT value. Variables were tested using the chi-square test or the Kruskal-Wallis test. The VNCa CT and CT values were tested using the Scheffe test for multiple comparisons. All variables were analyzed as independent variables affecting the VNCa CT values around the lesion in the multiple regression analysis.

RESULT

There were 35 men and 38 women. The mean patient age was 50.0 ± 19.5 years (range: 8-86). The VNCa CT values (- 6.2 ± 34.3) around the lesion in patients with RCs were significantly higher than those in patients with dentigerous cysts (- 44.4 ± 28.6) and odontogenic keratocysts (- 67.3 ± 19.5). In multiple regression analysis, the VNCa CT values around the lesion showed a significant positive correlation with histological results (regression coefficient: - 0.605, P < 0.001).

CONCLUSION

The presence of BME is associated with radicular cysts, and DECT can be used as an auxiliary tool for radicular cyst diagnosis.

Management of transient bone osteoporosis: a systematic review

INTRODUCTION

Transient bone osteoporosis (TBO) is characterized by persistent pain, loss of function, no history of trauma and magnetic resonance image (MRI) findings of bone marrow edema.

SOURCE OF DATA

PubMed, Google scholar, EMABSE and Web of Science were accessed in February 2023. No time constrains were used for the search.

AREAS OF AGREEMENT

TBO is rare and misunderstood, typically affecting women during the third trimester of pregnancy or middle-aged men, leading to functional disability for 4-8 weeks followed by self-resolution of the symptoms.

AREAS OF CONTROVERSY

Given the limited evidence in the current literature, consensus on optimal management is lacking.

GROWING POINTS

This systematic review investigates current management of TBO.

AREAS TIMELY FOR DEVELOPING RESEARCH

A conservative approach leads to the resolution of symptoms and MRI findings at midterm follow-up. Administration of bisphosphonates might alleviate pain and accelerate both clinical and imaging recovery.

Displaced femoral neck fracture in a pregnant patient diagnosed with transient osteoporosis of the hip

Transient osteoporosis of pregnancy (TOP) is a self-limiting pathology with unspecified etiology. It is typically found in women in late pregnancy or early postpartum. A femoral neck fracture is an infrequent complication. Herein, we describe a TOP case in a 38-year-old female who suffered a displaced sub-capital femoral neck fracture without obvious trauma at 28 weeks of gestation. The patient underwent operative treatment using closed reduction and internal fixation (CRIF), using cannulated screws, with no intraoperative complications. The postoperative radiograph revealed a collapse and further displacement of the femoral neck. A decision was made to postpone a definitive treatment to a postpartum date. The patient underwent a cesarean section at 38-week of gestation with no complications. At her latest follow-up, 24 months postoperatively, the patient was asymptomatic. Pelvic and hip radiographs demonstrated consolidation of the fracture. Level of evidence: IV.

Transient regional osteoporosis of the ankle with shifting bone marrow edema pattern within the joint

We describe a case of bone marrow edema (BME) shifting within one ankle joint in a 35-year-old - male patient. He presented with increasing pain and no history of trauma. Clinically no local swelling was found and laboratory findings and plain x-ray studies were normal. He did not improve on non-steroidal anti-inflammatory drugs for 2 weeks. A Gadolinium enhanced magnetic resonance imaging showed no evidence of synovitis, but BME was observed in the talus and transient regional osteoporosis was diagnosed. The patient was treated conservatively by protective partial weight bearing of the affected joint and he showed partial improvement after 6 months of daily treatment with Calcitonin Salmon nasal spray. A magnetic resonance imaging after 6 months showed that the BME had shifted anteriorly with complete resolution at the initial site. Transient regional osteoporosis is a rare self-limiting syndrome characterized by sudden onset of joint pain, functional limitations and spontaneous recovery, without preceding trauma. The condition may present as one episode affecting only one joint or recurrent episode that may affect multiple joints. BME between different compartments of the same joint can occur and has been reported only in a few case reports in the knee joint. The case is discussed and the literature is reviewed.

Deep Learning for the Differential Diagnosis between Transient Osteoporosis and Avascular Necrosis of the Hip

Differential diagnosis between avascular necrosis (AVN) and transient osteoporosis of the hip (TOH) can be complicated even for experienced MSK radiologists. Our study attempted to use MR images in order to develop a deep learning methodology with the use of transfer learning and a convolutional neural network (CNN) ensemble, for the accurate differentiation between the two diseases. An augmented dataset of 210 hips with TOH and 210 hips with AVN was used to finetune three ImageNet-trained CNNs (VGG-16, InceptionResNetV2, and InceptionV3). An ensemble decision was reached in a hard-voting manner by selecting the outcome voted by at least two of the CNNs. Inception-ResNet-V2 achieved the highest AUC (97.62%) similar to the model ensemble, followed by InceptionV3 (AUC of 96.82%) and VGG-16 (AUC 96.03%). Precision for the diagnosis of AVN and recall for the detection of TOH were higher in the model ensemble compared to Inception-ResNet-V2. Ensemble performance was significantly higher than that of an MSK radiologist and a fellow (P < 0.001). Deep learning was highly successful in distinguishing TOH from AVN, with a potential to aid treatment decisions and lead to the avoidance of unnecessary surgery.

Inflammation and nutrition based screening tests for detection of infection in cases of rapid hip destruction

Preoperative diagnosis of infection is important for appropriate surgical treatment of patients with rapid hip destruction (RHD). We investigated whether test results, including inflammatory and nutritional markers, could be used to accurately differentiate infectious and non-infectious RHD. Fifty patients with RHD who underwent total hip arthroplasty within a year of onset were observed. Infectious RHD was defined as ≥ 2 positive serological inflammatory, microbiological, or pathological evaluations. The albumin to globulin ratio (AGR), C-reactive protein (CRP)/albumin ratio (CAR), Glasgow prognostic score (GPS), modified GPS (mGPS), prognostic nutritional index (PNI), geriatric nutritional risk index (GNRI), and platelet to lymphocyte ratio (PLR) were calculated from the blood test results. In the infectious group, the white blood cell count, platelet count, CRP level, erythrocyte sedimentation rate, CAR, GPS, mGPS, and PLR were significantly higher, while the albumin level, AGR, PNI, and GNRI were significantly lower. The CRP and albumin levels showed the highest sensitivity (1.00 for both; specificity of 0.87 and 0.73, respectively) in diagnosing infectious RHD. Combining these measurements (CAR) increased the specificity to 0.92. The accuracy of other nutritional assessments was good. Thus, nutritional assessment as well as conventional assessment of the inflammatory response can improve the accuracy of preoperative diagnosis of infectious RHD.

Transient regional osteoporosis of the hip with extensive bone marrow edema (BME): Dramatic improvement after three months of Alendronate therapy

Transient osteoporosis of the hip, also termed transient bone marrow edema, is a painful condition often occurring after trivial trauma. It can be diagnosed with MRI in patients whose radiographs are negative or inconclusive. In this case report we describe a 39-year-old female patient with this rare entity, who was successfully treated with oral Alendronate, active vitamin D and calcium supplementation combined with avoiding of weight bearing on the affected hip. She improved clinically within three months and on contrast enhanced MRI studies, as performed before and after treatment, complete regression of bone marrow edema was shown already after three months of treatment. The literature was reviewed regarding the pathophysiology of transient osteoporosis of the hip and the beneficial effects of Alendronate in this domain. The report is important because it will increase the awareness among clinicians and radiologists about this entity, as in neglected cases transient regional osteoporosis of the hip may progress to avascular necrosis with complete loss of hip function.

Similarity in Sequential Bilateral Transient Osteoporosis of the Hip: A Report of 3 Cases

CASE

Three middle-aged men with habitual drinking developed unilateral hip pain and were referred for osteonecrosis of the femoral head (ONFH). Radiographs showed osteopenia, and magnetic resonance imaging (MRI) showed diffuse bone marrow edema (BME). After several months, the patients' symptoms resolved and radiographic images normalized. More than 6 months later, the contralateral side showed the same clinical course.

CONCLUSION

Transient osteoporosis of the hip (TOH) resembles ONFH but heals spontaneously. We report 3 rare cases of sequential TOH, similar in that they occurred in middle-aged male habitual drinkers at risk for ONFH, characterized by diffuse BME on MRI and radiographic resolution.

Magnetic resonance imaging of avascular necrosis of the femoral head: predictive findings of total hip arthroplasty

Background

Avascular osteonecrosis of the femoral head (AVNFH) is an ischemic condition which despite different treatments often leads to collapse of the femoral head and to total hip arthroplasty. However, the magnetic resonance imaging findings predisposing to disease progression and total hip arthroplasty are somewhat elusive.

Purpose

To evaluate the magnetic resonance imaging findings of AVNFH and to assess the patterns of findings which may predict total hip arthroplasty.

Materials and methods

A retrospective study was conducted with a total of 18 diagnosed AVNFH treated with core decompression combined with intraosseous stem cell treatment. After treatment, magnetic resonance imaging follow-ups were done at three-month and one-year follow-up or until total hip arthroplasty. Association Research Circulation Osseous classification and magnetic resonance imaging findings such as the size and the location of the AVNFH, bone marrow edema in femoral neck, effusion and subchondral fracture were evaluated.

Results

Hips advancing to total hip arthroplasty have more often bone marrow edema in femoral neck (90% vs. 0%), adjacent to necrotic lesion (100% vs. 43%) and in acetabulum (90% vs. 14%), but also subchondral fractures (70% vs. 0%), effusion (80% vs. 29%), and synovitis (80% vs. 14,3%). The greater size and the lateral weight-bearing location of the necrotic lesion also predicted future total hip arthroplasty.

Conclusion

Hips advancing to total hip arthroplasty have often a combination of pathognomonic AVNFH imaging findings compared to hips not advancing to total hip arthroplasty.

Calcium dobesilate (Doxium®) in bone marrow edema syndrome and suspected osteonecrosis of the hip joint - A case series

Osteonecrosis of the femoral head is a disease that leads to gradual degeneration of the hip joint causing immobility and a devastating impairment of quality of life. Early stage disease is characterised by a bone marrow edema of the proximal femur, a sight it shares with bone marrow edema syndrome. Although total hip arthroplasty offers quick symptom relief and functionally appealing results the treatment remains challenging, with its particularly young patients and considering limited non-invasive treatment options. We treated 6 patients with bone marrow edema in MRI and suspected osteonecrosis of the hip joint with calcium dobesilate, a vasoactive agent used in the treatment of diabetic retinopathy. We could demonstrate rapid symptom relief and concomitant disease remission on control MRI in early stage disease without any adverse events. Patients at advanced stages benefited in terms of pain reduction, but the treatment failed to halt disease progression. To the best of our knowledge, this is the first report of the therapeutic administration of calcium dobesilate in patients with bone marrow edema syndrome or osteonecrosis of the hip joint.

Bone marrow edema in non-traumatic hip: high accuracy of dual-energy CT with water-hydroxyapatite decomposition imaging

OBJECTIVES

To evaluate the diagnostic performance of dual-energy CT with water-hydroxyapatite (HAP) imaging for bone marrow edema in patients with non-traumatic hip pain.

METHODS

Forty patients (mean age, 58 years; 16 male and 24 female) who underwent rapid kVp-switching dual-energy CT and MRI within 1 month between April 2018 and February 2019 with hip pain but no trauma were enrolled. Two radiologists retrospectively evaluated 80 hip joints for the presence, extent (femoral head involved, head and neck, and head to intertrochanter), and severity (mild edema, moderate, severe) of bone marrow edema on dual-energy water-HAP images. Water mass density (mg/cm³) on water-HAP images was determined with region of interest-based quantitative analysis. MRI served as the standard of reference.

RESULTS

Sensitivity, specificity, and accuracy of readers 1 and 2 for the identification of bone marrow edema in water-HAP images were 85% and 85%, 93% and 73%, and 89% and 79%, respectively. The area under the receiver operating characteristic curve was 0.96 for reader 1 and 0.91 for reader 2 for differentiation of the presence of edema from no edema. The optimal water mass density to classify the presence of edema for reader 1 was 951 mg/cm³ with 93% sensitivity and 93% specificity and for reader 2 was 957 mg/cm³ with 80% sensitivity and 80% specificity. The more severe the edema, the higher was the mean water density value (p < 0.035).

CONCLUSION

Dual-energy water-HAP images showed good diagnostic performance for bone marrow edema in patients with non-traumatic hip pain.

KEY POINTS

• Dual-energy water-HAP imaging depicts bone marrow edema in patients with non-traumatic hip pain and may serve as an alternative to MRI in select patients. • A cutoff value of 951 mg/cm³mean water mass density results in 93% sensitivity and 93% specificity for the detection of bone marrow edema. • The more severe the bone marrow edema, the higher the mean water density value.

Global urinary metabolic profiling of the osteonecrosis of the femoral head based on UPLC-QTOF/MS

INTRODUCTION

Osteonecrosis of the femoral head (ONFH), one of the widespread orthopedic diseases with a decrease in bloodstream to the femoral head, is frequently accompanied by cellular death, trabecula fracture, and collapse of the articular surface. The exactly pathological mechanism of ONFH remains to explore and further identify.

OBJECTIVES

The aim was to identify the global urinary metabolic profiling of ONFH and to detect biomarkers of ONFH.

METHODS

Urine samples were collected from 26 ONFH patients and 26 healthy people. Ultra-performance liquid chromatography-quadrupole time of flight tandem mass spectrometry (UPLC-QTOF/MS) in combination with multivariate statistical analysis was developed and performed to identify the global urinary metabolic profiling of ONFH.

RESULTS

The urinary metabolic profiling of ONFH group was significantly separated from the control group by multivariate statistical analysis. 33 distinctly differential metabolites were detected between the ONFH patients and healthy people. Sulfate, urea, Deoxycholic acid and PE(14:0/14:1(9Z)) were screened as the potential biomarkers of ONFH. In addition, the up/down-regulation of sulfur metabolism, cysteine and methionine metabolism, glycerophospholipid metabolism, and histidine metabolism were clearly be associated with the ONFH pathogenic progress.

CONCLUSION

Our results suggested that metabolomics could serve as a promising approach for identifying the diagnostic biomarkers and elucidating the pathological mechanism of ONFH.

Study of Osteocyte Behavior by High-Resolution Intravital Imaging Following Photo-Induced Ischemia

Ischemic injuries and local hypoxia can result in osteocytes dysfunction and play a key role in the pathogenesis of avascular osteonecrosis. Conventional imaging techniques including magnetic resonance imaging (MRI) and computed tomography (CT) can reveal structural and functional changes within bony anatomy; however, characterization of osteocyte behavioral dynamics in the setting of osteonecrosis at the single cell resolution is limited. Here, we demonstrate an optical approach to study real-time osteocyte functions in vivo. Using nicotinamide adenine dinucleotide (NADH) as a biomarker for metabolic dynamics in osteocytes, we showed that NADH level within osteocytes transiently increase significantly after local ischemia through non-invasive photo-induced thrombosis of afferent arterioles followed by a steady decline. Our study presents a non-invasive optical approach to study osteocyte behavior through the modulation of local environmental conditions. Thus it provides a powerful toolkit to study cellular processes involved in bone pathologies in vivo.

Difficulty in the diagnosis of bone and joint pain associated with pediatric acute leukemia; comparison with juvenile idiopathic arthritis

OBJECTIVES

Acute leukemia often causes osteoarthralgia. The aim of this study is characterization of leukemia-associated osteoarthralgia in comparison with juvenile idiopathic arthritis (JIA).

METHODS

We retrospectively reviewed clinical records of 31 patients with acute leukemia and 13 patients with articular JIA diagnosed between January 2008 and March 2013. Clinical and laboratory findings at the initial examination were compared among the three groups; 10 leukemia with and 21 leukemia without osteoarthralgia and 13 JIA groups.

RESULTS

Eleven of the 31 leukemic patients (35%) had osteoarthralgia before the diagnosis of leukemia. Peripheral leukemic cells were initially absent in 10 of the 31 leukemia patients including three with osteoarthralgia. Platelet counts over 300 × 10⁹/L were common in JIA, but not in osteoarthralgia group. Mean serum lactate dehydrogenase levels were higher in both of the leukemia groups than JIA group but often within normal or near-normal levels in the leukemia groups. Magnetic resonance imaging was examined in three leukemic patients and demonstrated osteomyelitis-like bone marrow edema in two and periarticular infiltration similar to synovitis in one patient. Three leukemic patients with osteoarthralgia showed partial and transient responses to antibiotic therapy.

CONCLUSIONS

Leukemia-associated osteoarthralgia is often indistinguishable from rheumatic diseases by imaging and laboratory findings and should be confirmed by bone marrow examination.

Nontraumatic Osteonecrosis of the Femoral Head: Where Do We Stand Today? A Ten-Year Update

➤ Although multiple theories have been proposed, no one pathophysiologic mechanism has been identified as the etiology for the development of osteonecrosis of the femoral head. However, the basic mechanism involves impaired circulation to a specific area that ultimately becomes necrotic.➤ A variety of nonoperative treatment regimens have been evaluated for the treatment of precollapse disease, with varying success. Prospective, multicenter, randomized trials are needed to evaluate the efficacy of these regimens in altering the natural history of the disease.➤ Joint-preserving procedures are indicated in the treatment of precollapse disease, with several studies showing successful outcomes at mid-term and long-term follow-up.➤ Studies of total joint arthroplasty, once femoral head collapse is present, have described excellent outcomes at greater than ten years of follow-up, which is a major advance and has led to a paradigm shift in treating these patients.➤ The results of hemiresurfacing and total resurfacing arthroplasty have been suboptimal, and these procedures have restricted indications in patients with osteonecrosis of the femoral head.

Imaging evaluation of patients with osteonecrosis of the femoral head

Imaging modalities for the diagnosis of osteonecrosis (ON) of the femoral head have been studied extensively, but there have been few reports strictly addressing radiographic evaluation. The purpose of this report is to examine the use and role of (1) plain radiographs, (2) magnetic resonance imaging (MRI), (3) computerized tomography (CT), (4) bone scanning, and (5) positron emission topography (PET) for the diagnostic evaluation of ON. Plain radiographs are a mainstay in diagnosis but have very low sensitivity for early ON. MRI is the gold standard for diagnostic evaluation but may not identify subchondral fractures on collapse as well as CT scan or tomogram. Bone scanning should not be used for diagnosis due to its low sensitivity. PET scanning does not have a definitive role in diagnosis yet. Future research should focus on the role of new imaging technologies in evaluation.

Initial experiences with a new MRI scoring system for differentiating advanced femoral osteonecrosis from tubercular arthritis

The purpose of this study was to formulate a magnetic resonance imaging-based scoring system for differentiating tuberculous arthritis from advanced osteonecrosis of the femoral head. Magnetic resonance imaging findings in 18 hips with tuberculous arthritis and 36 hips with advanced osteonecrosis of the femoral head were reviewed retrospectively. Confirmation of tuberculous arthritis was based on enzyme-linked immunosorbent assay and/or synovial biopsy. Osteonecrosis was confirmed either by histopathology or eventual radiographic evidence on follow-up. The findings were analyzed with an emphasis on the changes in femoral head marrow, joint cavity, synovium, acetabulum, and contrast enhancement patterns. A score of 2 was assigned for the presence of each of the following: T2 hyperintensity of the femoral head, synovial hypertrophy, articular cartilage erosion, unilateral involvement of the femoral head, acetabular edema/sclerosis, and enhancement of the involved head. A score of 1 was assigned for each of the following: joint effusion, edema of adjacent marrow, and enhancement of adjacent soft tissue. A cutoff value of 10 of 15 points was considered to be positive for tuberculous arthritis. Sixteen of 18 cases of tuberculous arthritis were correctly identifiable on the basis of this scoring system. The 2 remaining cases had a score of 9. No case of osteonecrosis of the femoral head scored more than 9. A score of 10 for a positive diagnosis of tuberculous arthritis had a sensitivity of 88.89% and specificity of 100%. Positive and negative predictive values were 1 and 0.94, respectively. Statistical significance for each of the parameters and the entire model was established with logistic regression analysis. This new scoring system is effective in solving the imaging dilemma pertinent to endemic regions.

Evaluation of transient osteoporosis of the hip in magnetic resonance imaging

Transient osteoporosis is a relatively rare condition of unknown etiology that causes temporary bone loss. The syndrome is characterized by self-limited course and spontaneous resolution after 6 to 12 months. The pathogenesis of transient osteoporosis is not fully understood but several hypotheses that have been proposed include trauma, neurovascular dysfunction and transient hyperemia. Clinical manifestations include sudden onset of pain in the hip that usually worsens with weight bearing and leads to functional disability involving the affected extremity. Radiographs are frequently unremarkable, but may reveal periarticular osteopenia 3-6 weeks after the onset of clinical symptoms. There is no radiographic evidence of demineralization during the early phase of syndrome, as a result advanced imaging is required. Magnetic resonance imaging is the most sensitive and predictable test for an early diagnosis and monitoring of disease progression.

Methodologies for semiquantitative evaluation of hip osteoarthritis by magnetic resonance imaging: approaches based on the whole organ and focused on active lesions

OBJECTIVE

As a wider variety of therapeutic options for osteoarthritis (OA) becomes available, there is an increasing need to objectively evaluate disease severity on magnetic resonance imaging (MRI). This is more technically challenging at the hip than at the knee, and as a result, few systematic scoring systems exist. The OMERACT (Outcome Measures in Rheumatology) filter of truth, discrimination, and feasibility can be used to validate image-based scoring systems. Our objective was (1) to review the imaging features relevant to the assessment of severity and progression of hip OA; and (2) to review currently used methods to grade these features in existing hip OA scoring systems.

METHODS

A systematic literature review was conducted. MEDLINE keyword search was performed for features of arthropathy (such as hip + bone marrow edema or lesion, synovitis, cyst, effusion, cartilage, etc.) and scoring system (hip + OA + MRI + score or grade), with a secondary manual search for additional references in the retrieved publications.

RESULTS

Findings relevant to the severity of hip OA include imaging markers associated with inflammation (bone marrow lesion, synovitis, effusion), structural damage (cartilage loss, osteophytes, subchondral cysts, labral tears), and predisposing geometric factors (hip dysplasia, femoral-acetabular impingement). Two approaches to the semiquantitative assessment of hip OA are represented by Hip OA MRI Scoring System (HOAMS), a comprehensive whole organ assessment of nearly all findings, and the Hip Inflammation MRI Scoring System (HIMRISS), which selectively scores only active lesions (bone marrow lesion, synovitis/effusion). Validation is presently confined to limited assessment of reliability.

CONCLUSION

Two methods for semiquantitative assessment of hip OA on MRI have been described and validation according to the OMERACT Filter is limited to evaluation of reliability.

Transient osteoporosis of the hip, complete resolution after treatment with alendronate as observed by MRI description of eight cases and review of the literature

Transient osteoporosis of the hip (TOH), also referred to as transient bone marrow edema syndrome, is most common in middle-aged men and often after trivial trauma or sport-related injuries. Diagnosis is usually made by eliminating other possible causes of hip pain. Magnetic resonance imaging (MRI) plays an important role in diagnosis and demonstrates a typical pattern of bone marrow edema (BME) in the form of diffuse low signal on T1-weighted images and high signal on T2 fat-suppressed or short T1 inversion recovery images. No consensus exists about the management of TOH, as it may progress to avascular necrosis. We describe eight cases of TOH treated with alendronate resulting in improvement of pain and function and complete resolution of BME on MRI. The literature is reviewed regarding TOH and the relationship with bone marrow edema syndrome, avascular necrosis of the hip, and regional migratory osteoporosis. To our knowledge, this is the first report describing the improvement of this condition after of alendronate with documented radiological improvement on follow-up MRI.

Magnetic resonance imaging of subchondral bone marrow lesions in association with osteoarthritis

OBJECTIVES

This nonsystematic literature review provides an overview of magnetic resonance imaging (MRI) of subchondral bone marrow lesions (BMLs) in association with osteoarthritis (OA), with particular attention to the selection of MRI sequences and semiquantitative scoring systems, characteristic morphology, and differential diagnosis. Histologic basis, natural history, and clinical significance are also briefly discussed.

METHODS

PubMed was searched for articles published up to 2011, using the keywords bone marrow lesion, osteoarthritis, magnetic resonance imaging, bone marrow edema, histology, pain, and subchondral.

RESULTS

BMLs in association with OA correspond to fibrosis, necrosis, edema, and bleeding of fatty marrow as well as abnormal trabeculae on histopathology. Lesions may fluctuate in size within a short time and are associated with the progression of articular cartilage loss and fluctuation of pain in knee OA. The characteristic subchondral edema-like signal intensity of BMLs should be assessed using T2-weighted, proton density-weighted, intermediate-weighted fat-suppressed fast spin echo or short tau inversion recovery. Several semiquantitative scoring systems are available to characterize and grade the severity of BMLs. Quantitative approaches have also been introduced. Differential diagnoses of degenerative BMLs include a variety of traumatic or nontraumatic pathologies that may appear similar to OA-related BMLs on MRI.

CONCLUSIONS

Subchondral BMLs are a common imaging feature of OA with clinical significance and typical signal alteration patterns, which can be assessed and graded by semiquantitative scoring systems using sensitive MRI sequences.

Evaluation of osteoarthritis in cats: novel information from a pilot study

OBJECTIVE

To describe structural changes associated with osteoarthritis (OA) in cats and to quantify OA-associated disability using functional evaluations.

STUDY DESIGN

Cross-sectional pilot study with longitudinal data.

ANIMALS

Normal cats (n = 2) and coxofemoral joint OA cats (n = 4) were evaluated by physical examination, radiography, and magnetic resonance imaging (MRI).

METHODS

Structural changes related to OA were scored using computed radiographs (CR) and MRI. Functional evaluation consisted of podobarometric gait analyses performed using a pressure-sensitive mattress and motor activity assessments using collar-attached, accelerometer-based activity sensors.

RESULTS

Structural scores for the coxofemoral joint OA-related lesions were lower in normal cats than OA cats for MRI (P = .07). Use of MRI allowed for whole-organ assessment of the coxofemoral joint. Pelvic limb peak vertical ground reaction force (PVF) was higher in normal cats than OA cats (P = .10). During the night, motor activity was greater in normal cats than OA cats (P = .04). PVF was positively correlated with mean motor activity (Spearman coefficient [Rho] = 0.83, P = .04) and negatively correlated with age and MRI structural score (Rho = -0.93 and -0.79, P < .01 and .06, respectively).

CONCLUSIONS

This study provides the first description of OA-related lesions in cats using MRI. Gait analysis and accelerometry should be considered as objective tools to characterize OA-associated disability, although these assessments were weakly correlated with structural changes.

Imaging of lower limb cartilage

The cartilage of the lower limb joints is exposed to high levels of mechanical stress and therefore is a frequent site of degenerative and traumatic lesions. Magnetic resonance imaging (MRI) is the modality of choice for the assessment of these cartilage lesions. To date, clinically available sequences have focused on morphological defects and cartilage loss. Efforts have been made in recent years to depict cartilage lesions at an earlier stage, with new quantitative sequences focusing on the biochemical assessment of tissue.After a brief review of the hyaline cartilage structure, we review the current morphological imaging methods and the biochemical MRI techniques to assess the cartilage. We then illustrate the application of these MRI sequences for the most common degenerative and traumatic disorders affecting lower limb cartilage.

The bone marrow lesion in osteoarthritis

Osteoarthritis (OA) is considered a multifactorial disease whose development and progression may include several structural abnormalities aside from cartilage destruction. Bone marrow lesions (BMLs) have been reported to be associated with OA pathology, and several studies have advocated its close connection to the severity of joint structural alterations and pain, the main OA clinical manifestation. Hence, BMLs may not only affect subchondral bone and its neuronal and vascular structures but also negatively influence the adjacent tissues. Here, we analyze the pathophysiology and natural history of OA-associated BMLs and their potential relevance to the radiographic progression and severity of the disease. The notion that BMLs may be a precursor to additional articular abnormalities, can be a potential risk factor for development of OA, and may serve as an additional diagnostic tool and a therapeutic target are further discussed.

Transient osteoporosis of the hip

Transient osteoporosis of the hip is an uncommon cause of hip pain, mostly affecting healthy middle-aged men and also women in the third trimester of pregnancy. We present a case of transient osteoporosis of the hip in a 33-year-old non-pregnant female patient. This case highlights the importance of considering a diagnosis of transient osteoporosis of the hip in patients who present with hip pain.