Friday, March 31, 2017

Hip Air Arthrogram and Steroid Injection

I perform steroid injections for my patients to treat hip pain. When the pain is coming from inside the hip joint,such as in cases of osteoarthritis, avascular necrosis, hip impingement, or labral tear, an intra-articular injection is indicated. These injections are performed with fluoroscopic guidance (using a real-time x-ray machine). Usually intra-articular contrast is used to verify position of the needle.
I prefer to inject air rather than commercial contrast material since I believe that air is safer. Other doctors ask me how I can be sure that the injection is going in the right place with just using air, they ask how can you see the air. Here is an example of a recent patient with an air arthrogram of the hip:
Air Arthrogram Right Hip Joint Injection
Right Hip Air Arthrogram
As can be seen in the above images, the right side shows air injected into the inferior region of the femoral neck. The air then naturally travels to the inferior region of the hip joint and encircles the hip joint in the area just outside the labrum This is seen as a lighter density coming from the inferior hip and heading in a direction up and lateral, approximately perpendicular to the femoral neck.
In this case the patient was highly satisfied with the steroid injection and had relief of hip pain.

Thursday, February 16, 2017

Failed fixation of hip fracture with subsequent conversion to hemiarthroplasty

Hip Nail Failure Case

This case involves an elderly female who fell at home and fractured her hip. She was evaluated with x-rays and found to have an intertrochanteric hip fracture. Here are the initial x-rays:

I consider this fracture pattern to be unstable due to the reverse obliquity of the fracture line. The patient was optimized and underwent intramedullary fixation with a cephalomedullary device (Zimmer Natural Nail). Here are the intra-operative fluoroscopy images.

As seen above, the cephalomedullary nail is in excellent position and the fracture is well reduced and aligned. Here are x-rays taken at routine follow up evaluations:

Here are x-rays at a later date:

You can see evidence of screw migration and fixation failure. At this point the patient had severe symptoms. A CT of the hip was obtained. Here are the coronal and sagittal reconstructions:

As seen, the hip screw has penetrated the femoral head and failed. There is a nonunion of the fracture as well. This patient required additional surgical treatment. Removal of the hip nail and placement of a partial hip replacement or hemiarthroplasty was recommended. Revision fixation was not considered advisable due to damage to the head and high risk of failure.

Here are the final x-rays showing the long stemmed partial hip replacement. The Zimmer/Biomet Arcos Modular Femoral Revision system was used.

The patient recovered well from the surgery and has regained functional abilities. I have noticed a higher incidence of these kinds of failures over the last few years. I suspect it is related to an aging population with more severe osteoporosis. Nevertheless, I think there is room for improvement in implant design to improve the success rate.