Posttraumatic Avascular Necrosis of the Hip
Abstract
Avascular necrosis of the hip has many causes, with trauma being one. Its diagnosis becomes difficult after an injury, as the potential of AVN isn’t the main focus, but rather healing the injury itself. AVN can take months to years to develop, depending on MOI and severity. It can also be caused by chronic alcohol, steroid use, and idiopathic disease. No matter the cause, it leads to a disruption in blood flow and supply to the acetabulum and femoral head. In this patient’s case, after a head-on collision, the femur was pushed into the acetabulum, crushing its blood supply. In this patient’s case, she did not realize there was pain and necrosis in her hip due to being non weight bearing for an ankle injury and surgery months prior.
This patient came to the orthopedic clinic with hip and groin pain for multiple weeks after beginning to walk from a previous ankle surgery and car accident. Otherwise healthy female, with X rays showing flattening and shrinking of the right femoral head, along with collapse of the joint space. The history, imaging, and symptoms aligned with a diagnosis of avascular necrosis The left hip joint space was maintained, and appeared normal for age, although some evidence of osteoarthritis was present.
The patient was initially seen for an ankle surgery following a motor vehicle accident. After her surgery she was non weight bearing for multiple weeks, preventing her from noticing the pain of the developing AVN. Once her therapy progressed to walking, she noticed groin pain. X-rays revealed fairly progressed AVN, requiring surgery. A total hip replacement was recommended and performed with no complications via posterior/lateral approach. Follow up visits were optimistic, with therapy and ambulation progressing as planned. Patient says both ankle and hip have become much less painful, and has returned to activities of daily life without complication. Follow up in 1 year was recommended.
The objective of this study is to understand the slow progression and nature of AVN, and to consider the diagnosis based on certain MOA. Although it is not a diagnosis that will be found right after an injury, it is important to consider it occuring down the road, and to order repeat imaging, and discuss warning signs with patients. Repeat imaging after traumatic orthopedic injuries is very important to not only track healing progress, but to also assess for any missed injuries that may have become present over time.