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 just a 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.
All imaging studies should begin with radiographs that help differentiate many benign conditions at the outset from what might appear to be very confusing on magnetic resonance imaging (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 a referred pain, but it alerts the radiologist and the referring physician to the possibility of more ominous conditions like the beginning of an avascular hip necrosis. We routinely perform coronal T1-weighted and short-tau inversion recovery (STIR) sequences of the pelvis that include both hips. This helps in conditions like avascular necrosis (AVN) that might be bilateral. It also helps in comparing common anatomical variants or clarifying imaging artifacts. Then we 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 the MRI is equivocal, we suggest the referring physician put the patient on restricted weight bearing and repeat the MRI study in a month.
In this chapter, we provide a brief introduction of the hip pathologies one that is most likely to seen and then describe some relatively less common conditions. Interested readers are referred to the references at the end of the chapter for further studies.
AVN is discussed first, followed by less common conditions, and then basic concepts of femoroacetabular impingement 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 like sacral fractures and some basic concepts of pubalgia or “sports hernias” are discussed briefly.
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 of ...