Anatomy clinical correlates: Hip, gluteal region and thigh

At osmosis, we are not too sure where the phrase ‘break a leg’ comes from, but we are pretty sure it is not meant to be taken literally. In this video, we are going to discuss the anatomy behind the clinical conditions affecting the hip, gluteal region, and thigh, and we hope you won't even break a sweat learning these conditions, let alone a leg!

Let’s start with femoral neck fractures, often simply called hip fractures. They can be classified as intracapsular or extracapsular fractures based on their anatomic location. Intracapsular fractures occur in the region of the femoral head and neck within the joint capsule of the hip, while extracapsular fractures occur outside the fibrous joint capsule, anywhere in the intertrochanteric or subtrochanteric area of the femur.

Hip fractures are typically caused by mechanical falls or a trauma such as a car crash. And while they can affect anyone, they’re more likely to occur in the eldery, because of associated conditions such as osteoporosis, or Vitamin D and calcium deficiency. The classic presentation of a hip fracture is an individual who presents after a fall, and has an acutely shortened, externally rotated leg on physical examination compared to the contralateral side. This is due to the attachment points and pull of the iliopsoas and gluteus muscles. Other clinical features of a hip fracture include hip or back pain; joint deformity; and inability to bear weight.

Intracapsular fractures are at risk of avascular necrosis and displacement of the femoral head, whereas extracapsular fractures are less likely to undergo avascular necrosis. See, with an intracapsular hip fracture, the retinacular arteries, branching mainly from the medial circumflex femoral arteries are disrupted, resulting in potential avascular necrosis to the femoral head as the artery within the ligament to the head of the femur isn’t able to ensure adequate blood supply on its own. Conversely, with extracapsular femoral neck fractures, these arteries are not disrupted and maintain their function.

Confirming the diagnosis of a hip fracture usually relies on anterior-posterior and lateral hip x-rays, but if x-rays are inconclusive in the context of strong clinical suspicion, a CT scan can be done. On imaging, intracapsular fractures can be identified by a loss of Shenton’s line, a line drawn from the inferior border of the superior pubic rami along the inferomedial border of the neck of the femur. Other features of an intracapsular fracture include a prominent lesser trochanter due to external rotation of the femur compared to the contralateral side, and shortening or angulation of the femoral neck.