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The hip joint is a ball and socket type of joint that is also the deepest joint in the body. Since this joint transfers weight from the upper body to the lower limbs, it is subject to a range of problems resulting from faulty weight-bearing positions in normal individuals to problems caused by wear and tear in those who are athletically active. Moreover, the symptoms related to hip pathology can have myriad of manifestations ranging from focal pain to vague groin pain. Sometimes, an injection of local anesthetics into the hip joint might be required to help diagnose the actual source of the patient’s pain.
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All imaging studies should begin with radiographs, which help differentiate many benign conditions at the outset from what might appear to be very confusing on MRI studies. One should also remember that any unexplained hip pain without any apparent radiographic findings is an indication for MRI if the pain does not resolve within a week. It might be referred pain, but it alerts the radiologist and the referring physician to the possibility of more ominous conditions, such as the beginning of avascular hip necrosis.
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We routinely perform coronal T1-weighted and short-tau inversion recovery (STIR) sequences of the pelvis that include both hips. This helps us evaluate for conditions such as avascular necrosis (AVN) that might be bilateral. It also helps in comparing common anatomical variants and clarifying imaging artifacts. We subsequently scan the affected hip in axial T1-weighted or proton density and fluid-sensitive sequences. T2-weighted fat-suppressed sequences are useful in assessing for edema. Sagittal sequences are added to assess the musculature and look for what, if any, part of the weight-bearing surface is affected. In case of hip arthrograms, sequences are tailored to assess for labral pathology. If AVN is a possible diagnosis but MRI is equivocal, we suggest the referring physician put the patient on restricted weight-bearing and repeat the MRI study in a month.
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In this chapter, we provide a brief introduction of the hip pathologies one is most likely to see and describe some relatively less common conditions. Interested readers are referred to the references at the end of the chapter for further studies.
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AVN is discussed first, followed by less common conditions. The basic concepts of femoral acetabular impingement (FAI) syndrome are discussed. This is becoming a more common diagnosis as knowledge of it spreads and the population becomes more physically active at a younger age. In the end, associated conditions such as sacral fractures and some basic concepts of pubalgia or “sports hernias” are briefly discussed.
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AVN is a crippling process that can lead to collapse of the femoral head and the onset of disabling osteoarthritis. There is a long list of conditions that predispose to AVN; some ...