It has been shown that the risk for vascular complications is significantly higher if a dislocated hip is not able to be reduced within 6 hours after the initial injury. A more positive prognosis also depends upon several factors including the severity of the injury; the severity of the dislocation including if the dislocation involved a fracture; and/or how well the ball fits back into the socket. The displaced femur bone often damages surrounding blood vessels which then limits the blood flow to the bone. This can lead to avascular necrosis (AVN) or sometimes referred to as osteonecrosis. AVN is the death of bone due to the lack of an adequate blood supply. This can occur in up to 40% of patients that had hip dislocations with a delayed reduction. (Gammons, Malanga, Talavera, Whitehurst, & Ho, 2014). As shown in the table below, there are several stages of AVN.
Staging of Avascular Necrosis
|0||No symptoms. Radiology results are normal. Lab findings abnormal.|
|I||Symptoms may be present. Labs, MRI and bone scan results abnormal. CT and X-ray will likely not show abnormalities.|
|II||Symptoms present. Radiographic tests are abnormal. A diagnosis may be made based on MRI.|
|III||Symptoms present. Collapse of bone may begin. The femoral head continues to maintain its shape.|
|IV||Collapse or flattening of the femoral head occurs. Irregularity of the joint space. CT scan shows sensitive abnormalities.|
|V||Radiology shows continued damage.|
|VI||Severe destruction of the femoral head and joint.|
Often the surgeon will bore holes into the bone to relieve pressure and open the possibility for new blood vessel formation in the channels or performing a bone graft. Once collapse of the femoral head occurs, the possibility of surgical repair is often too late and the damage is irreversible. (Tofferi, et al., 2014). Artificial hip replacement may be the last option. AVN can occur up to 2 years following the initial injury of dislocation.
For our civil newsletter and blog this month we are reviewing traumatic hip dislocations and delayed reduction. The blog topics for this month are:
- Hip Anatomy (3/2/15)
- Traumatic Dislocation (3/9/15)
- Avascular necrosis (3/16/15)
- Legal Implications (3/23/15)
Note: To see all posts in this topic, click here