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hemiarthoplasty

Hemiarthroplasty for hip fractures

As part of the requirements to be on staff at the hospital where I work, I am required to take trauma call.  One of the most frequent reasons for semi-urgent orthopedic surgery is a fractured hip.  A modification of the anterior approach is commonly used during the treatment of a certain subtype of hip fractures, and this procedure deserves an explanation.  A hip fracture that occurs at the base of the femoral neck, “a basi-cervical” femoral neck fracture, is best treated with half of hip replacement which is why this procedure is called a hemiarthroplasty.  Rather than proceeding with replacing both the acetabular and the femoral sides of the joint, it is usually only necessary to replace the femoral side of the joint, especially when there is minimal arthritis affecting the acetabulum.

There are several advantages to a hemiarthroplasty over direct repair of the fracture site.  First, a hemiarthroplasty usually allows the patient to bear full weight on the fracture immediately after the operation which is very beneficial in the elderly since their lack of balance and coordination (especially after a general anesthetic) limits their ability to put only a portion of their weight on the operated limb.  Second, this type of fracture occurs at a critical junction between the head and the neck of the femur, where the blood vessels that supply the femoral head are very susceptible to injury.  The most important blood vessels that supply the femoral head are a continuation of the superficial branch of the medial femoral circumflex artery, and this fracture pattern often tears those branches.  If the blood supply to the femoral head is interrupted, the head will almost certainly collapse as a result of avascular necrosis — death of the bone due to the lack of a blood supply.

Over the years, there have been a number of different classification systems that have sought to define the subtypes of femoral neck fractures and predict the risk of avascular necrosis as a function of the degree of displacement.  Ultimately, the majority of orthopedic surgeons tend to classify these fractures as unstable — those fractures with significant displacement — versus stable — those fractures that are impacted in place.

If the patient is elderly (and that used to mean over 65, but as Clint Eastwood recently remarked in our local paper, “80 years old?  It’s the new 79 and a half!”), or in poor health with medical problems that may result in poor healing, then often the best result surgical solution is a hemiarthroplasty.  This surgical procedure involves accessing the joint, removing the remainder of the femoral head, resecting some of the residual femoral neck, and inserting a femoral stem into the proximal portion of the femur.  Once the head of the femur has been replaced with a prosthesis, the joint needs to be re-located and the patient rehabilitated in such a way that the chance of complications from bed rest (pneumonia, blood clots, and bed sores) are minimized, rehabilitation is maximized (achieving pre-injury level of ambulatory ability), and the procedure is performed with predictable results.  In the correct setting, with one of many surgical techniques and variations, a hemiarthroplasty is capable of achieving these goals.

In the following example, we have the xrays of an elderly female patient who had a fall while at home.  The majority of these falls are what we call ground-level falls, meaning that the patient was standing, or sitting, and simply fell to the floor.  Typically some degree of pre-existing osteoporosis exists which results in a fracture of the femoral neck with what could be considered minimal trauma.  There also appears to be some evidence that the elderly may actually break their femurs by forceful contraction of the muscles about the hip, and then fall to the floor.  The proposed mechanism of this type of an injury is a slip where the patient tries to catch themselves, and the reflexive muscular contraction of the muscles of the hip may actually break the bone as the patient is trying to recover, and then they fall to the ground.

Here are a series of xrays taken in the emergency department of an 80 year old female who fell early in the morning while trying to use the bathroom.  Her medical conditions include early dementia with a degree of forgetfulness, slight confusion, and atrial fibrillation, for which she takes Coumadin.  The fracture should be fairly obvious, and the xray of just the left hip (the fractured side) is shown, in addition to a lateral view of the joint.

femoral neck fracture AP pelvis xray

femoral neck fracture AP hip xrayfemoral neck fracture lateral hip xray

After the patient was admitted to the hospital, her primary physician was consulted in order to obtain medical clearance.  In general, the rule of thumb is to operate on these patients as soon as possible; once they have been medically cleared.  Medical clearance means that they have been seen by their primary doctor or a consulting internal medicine physician called a hospitalist and everyone that there are no other diagnostic procedures that need to be done or other medical conditions that need to be treated before they are in suitable shape to go to the operating room.

In the operating room, the patient was positioned in the lateral position and an antero-lateral approach to the hip was made, which allows for excellent visualization of the fracture site, good access to the proximal portion of the femur, and may result in less chance of a post-operative dislocation.

lateral-hip-surgery-position-hemiarthroplasty lateral hip surgery prep and drape surgical incision hemiarthroplasty space suit hemiarthroplasty hip fracture surgery

In this series of pictures taken in the operating room, the patient is positioned in the lateral position and care is taken to protect the fragile skin over bony prominences with special pads.  The blue sticky pad on the patient’s right leg (the down leg) is a grounding pad for a device called the Bovie electrocautery, which is used to coagulate bleeding blood vessels and assist during surgical dissection.  In the second picture, a series of drapes are being used to cover the patients skin and establish a completely sterile field in which to operated.  In the 3rd and 4th pictures the operation is in progress.  You can click on any of the pictures to enlarge them, and for further explanation of our photo policy, click here.

The next picture is of the xray that is taken in the recovery room.  This film is used to verify that everything went as planned during the operation and here we can see the new femoral head (which in this case is a bipolar component) and the femoral stem inside of the intramedullary canal of the femur.  This patient will be mobilized by physical therapy on the first day after the operation, she will be able to bear full weight on the leg, and the therapists and her family will do their best to help her achieve functional independence after this operation.

 

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