MR Imaging of the Hip: An Update on Bone Marrow Edema.

Bone marrow edema (BME) represents a frequent and easily detected MR imaging finding that is recognized as a common source of pain. It is considered a nonspecific finding that constitutes a central component of a wide spectrum of pathologies affecting the hip joint, showing high variability in terms of prognosis and treatment requirements. Solid knowledge of the various BME patterns and associated imaging findings indicative of these conditions can aid in differentiation. Additionally, correlation with clinical and laboratory data are essential for arriving at a final diagnosis in several cases. In this review, we describe the disease characteristics and imaging findings and also highlight the differential diagnostic clues regarding common hip disorders associated with BME including avascular necrosis, transient osteoporosis, stress injuries, and infectious/inflammatory disorders.

Morel-Lavallée Lesions of the Knee: MRI Findings Compared With Cadaveric Study Findings.

OBJECTIVE: The purpose of this study is to describe the MRI findings and treatment decisions and outcome for Morel-Lavallée lesions (MLLs) of the knee and to investigate whether evidence exists to support an increased frequency of such lesions on the medial or lateral side by performing a cadaveric experiment. MATERIALS AND METHODS: In a 4-year period, 24 MRI studies of 24 consecutive patients (16 male patients and eight female patients) with knee MLLs were retrospectively reviewed. Patient demographic characteristics, treatment decisions and outcome, and associated injuries were recorded. The location of the MLL was categorized as medial, lateral, or global. Lesions were categorized according to an established MRI classification. During the cadaveric experiment, the compartmental pressures of the medial or lateral aspect of the knee were monitored in 20 cadaveric knees. The chi-square test, t test, and Pearson correlation were used for statistical analysis. RESULTS: MLLs were located medially in 16 patients, laterally in two patients, and globally in six patients. The medial location was significantly more common than a lateral or global location (p < 0.05). MLLs were classified as type I in 14 patients, type II in eight patients, and type III in two patients. MRI type was correlated with the chronicity of injury (r2 = 0.614; p = 0.0014). Fractures were the most common associated injuries, occurring in seven of 24 patients. In 17 patients, all of whom had conservatively treated type I or type II lesions, complete resolution of the MLL occurred. The maximum compartmental pressures were significantly higher on the lateral side than on the medial side (p < 0.0001). CONCLUSION: Knee MLLs have a predilection for the medial side, which may be attributed to the lower resistance in this location, and they have variable patterns on MRI, which correlate with chronicity. Conservative treatment of type I and II lesions seems effective.

Spectrum of skeletal disorders during the peripartum period: MRI patterns.

Pregnancy is a normal condition in which a combination of biomechanical and hormonal changes may result in a wide spectrum of skeletal disorders. Skeletal overloading due to postural and weight changes, combined with increased ligamentous laxity stemming from the action of relaxing and the risk of pregnancy-related osteoporosis during childbearing, childbirth, and postpartum, have been associated with various pathologies. Owing to the heterogeneity of proposed contributing factors, skeletal lesions in the peripartum period may be related to different pathogenesis depending on the metabolic status of the patient and the degree of biomechanical stress; thus, a fatigue or insufficiency discrimination is not always easy to make. When combined with clinical data, magnetic resonance imaging (MRI) is a powerful tool in clarifying the cause of skeletal pain in the majority of patients or alerting clinicians to proceed to further investigations. Early detection and tailored treatment are important in order to avoid disease progression and long-term restriction of daily activities which may have an adverse impact on the relationship between the mother and the newborn. This pictorial essay provides an overview of the MRI characteristics and pattern of involvement of skeletal lesions presenting during the peripartum period, combined with demographic data and dual-energy X-ray absorptiometry (DEXA) measurements.