A 42-year-old female presents to an outpatient clinic with a 3-week history of worsening left hip and groin pain. She has a history of systemic lupus erythematosus (SLE) diagnosed 1 year ago, which has been managed with long-term oral corticosteroids. She describes the pain as deep and aching, exacerbated by weight-bearing and movement, but present even at rest. She denies any specific trauma or fall. On physical examination, her vital signs are stable: temperature 36.8°C, blood pressure 128/82 mmHg, pulse 76/min, and respirations 14/min. Musculoskeletal examination of the left hip reveals tenderness to palpation over the greater trochanter and anterior joint line. There is a painful arc of motion, particularly with internal rotation and abduction, although the full range of motion is preserved. There is no significant effusion or erythema. Her gait appears antalgic. What is the most appropriate diagnostic approach and initial management strategy for this patient's condition?

A 10-year-old boy with a history of sickle cell anemia presents to a general outpatient clinic with a chief complaint of chronic, progressive left hip pain over the past month. He reports difficulty bearing weight and an antalgic gait. His mother notes he has had multiple admissions for vaso-occlusive crises, predominantly affecting his long bones. On physical examination, his left hip demonstrates a restricted range of motion, particularly with internal rotation and abduction, and palpation elicits mild discomfort in the inguinal region. The joint appears neither erythematous nor significantly warm to touch. His temperature is 36.8°C, blood pressure is 92/60 mmHg, pulse is 95/min, respirations are 18/min, and oxygen saturation is 98% on room air. Given this clinical presentation, what is the most probable diagnosis and the critical initial step in imaging and management?

A 55-year-old man presents to the emergency department with a 2-month history of progressive left hip pain. The pain is deep in the groin, constant, and significantly exacerbated by walking or bearing weight, making it difficult to perform daily activities. He denies any recent trauma or fall. His medical history includes a chronic autoimmune disorder for which he has been on high-dose oral corticosteroids for several years. On examination, his vital signs are stable: temperature 37.0°C, blood pressure 130/78 mmHg, pulse 80/min, respirations 16/min. He walks with an antalgic gait, favoring his left leg. Palpation of the hip joint itself is non-tender, but passive range of motion reveals marked pain and limitation, particularly with internal rotation and abduction of the left hip. Distal neurological and vascular exams are intact. Plain radiographs of the left hip appear unremarkable. Given the clinical presentation, which is the most appropriate next diagnostic step and initial therapeutic approach?