Overview of Hip Arthrogram
Arthrography, a kind of medical imaging, is particularly useful for children’s bone surgery. It’s especially handy in cases related to developmental hip dysplasia, a condition where the hip joint doesn’t develop properly. Because children have a lot of cartilage in their joints, which is harder to see than bone, making it difficult to figure out what’s going on just by looking at it.
In the past, arthrography was primarily used along with X-rays for diagnosing joint problems. Today, however, CT and MRI scans have mostly replaced arthrography for diagnosis. That said, arthrography is still pretty handy for use in the operating room. If a child is under general anesthesia for surgery, arthrography can provide vital information that could influence the surgical approach.
Arthrography is especially valuable for diagnosing and treating developmental dysplasia of the hip in children. A regular X-ray of the hip in children might not show all the needed information, because the structures that are made of cartilage in the hip do not show up as clearly as bone structures. Add to that, arthrography of the hip can help surgeons see these cartilaginous structures and helps surgeons to diagnose and to decide the proper treatment plan for such condition.
Performing arthrography is safe, minimally invasive, fast, and not too expensive, bearing in mind that it’s done properly. It’s considered very important in handling hip issues in children, because it allows doctors to see the head of the thigh bone (femoral head), hip socket (acetabulum), and any issues that could prevent the proper alignment of the hip.
Arthrography gives a clear view of the cartilage anatomy of the hip socket and the thigh bone’s head in children. It’s also a dynamic test, which means it can provide doctors with useful information about the stability and quality of the hip’s alignment. Thus, it plays a crucial role in deciding between closed (without surgery) and open (with surgery) methods of reduction (putting the joint back in place) when treating a child’s developmental hip dysplasia.
Anatomy and Physiology of Hip Arthrogram
Hip dysplasia in infants, also known as developmental dysplasia of the hip, is a condition that happens due to different reasons, including things like environmental factors, hormone changes, genetics, and the shape of the hip socket itself. One example of an environmental factor could be the way some cultures swaddle their babies, which can put harmful pressure on the hips. Hormonal changes in the baby before birth can sometimes induce joint laxity, causing the ball part of the joint (femoral head) to dislocate.
Initial instability in a newborn’s hip can lead to hip dysplasia. The insufficiency is often in the front or front-side of the socket (acetabulum). This can lead to partial dislocation and gradual full dislocation of the joint. Prolonged dislocation causes changes in the structure of the hip, and creates obstacles to putting the hip back into position later on. These structural changes can flatten the ball of the joint, change the angle of the socket, alter the concavity of the socket roof, and increase the thickness of the medial acetabular wall.
Over time, as the joint stays dislocated, it can affect the tissues around the joint and cause secondary changes such as contractures and deformations in the head of the femur. The labrum, an important structure around the rim of the hip socket, can become inverted and block the hip from being put back into its correct position. Similarly, the ligamentum teres, a ligament inside the hip joint, can thicken and lengthen and obstruct the hip’s reduction.
Consistent dislocation causes a build-up of fatty fibrous tissue, called a pulvinar, within the hip socket that can also prevent reduction. Furthermore, the transverse acetabular ligament found at the base of the hip socket can also develop an obstruction due to contractures from repeat dislocations. Also, the hip capsule can become stretched and wrapped around the tendon of a major hip muscle, known as the iliopsoas, resulting in an hourglass-shaped deformity that can hinder proper reduction.
An arthrography test, which involves a special dye and X-ray, can help figure out if any of these secondary issues are present. It can identify the position of the femoral head, the status of the labrum, ligamentum teres, and the other elements involved in the hip dysplasia. Constricted tissues, like an inverted labrum, thickened ligaments or contracted ligament, influence the success of the hip being put back into place.
The width of the medial dye pool, which is the space between the hip socket and the femoral head filled with dye, should be less than 6 millimeters to successfully put the hip back into position. If this space is above 6 millimeters, then there is a high chance of a soft tissue block to reduction. Good results can be expected from the reduction if these findings are addressed adequately.
Why do People Need Hip Arthrogram
If your child’s doctor suspects that they might have a condition called Legg-Calve-Perthes disease, a procedure known as hip arthrography may be used. Legg-Calve-Perthes disease affects the hip joint, where the thighbone and the hip meet, and it can disrupt the blood flow to the hip. This can lead to deformity or flattening of the hip bone. Through hip arthrography, the doctor can view the hip joint and the cartilage, which is a flexible tissue protecting the ends of the bones. This helps the doctors understand the layout and condition of the hip joint, and accordingly, they can decide the best method of treatment.
Hip arthrography has also been declared the go-to procedure when assessing another condition called developmental dysplasia of the hip. Developmental dysplasia of the hip represents a range of conditions where the hip joint does not form correctly. When conducting hip arthrography, doctors can analyze the stability of the hip joint and the shape of the top part of the thighbone or the femoral head. It helps in determining if further action, like open surgery, will be needed to fix the joint.
Besides assessing Legg-Calve-Perthes disease and developmental dysplasia of the hip, hip arthrography can be used to deal with other issues related to the pediatric hip joint. For instance, if a child has a fracture in the neck of the femur (the long bone in the thigh), arthrography can help visualize the joint surface and ensure any hardware, like pins or screws used for treatment, aren’t going into the joint. It also assists doctors in planning the best treatment for a child with any kind of deformity in the femoral head and accurately placing the femoral head during surgery, among others. So, in essence, this procedure is a critical tool for your child’s doctor in diagnosing and treating hip abnormalities in children.
When a Person Should Avoid Hip Arthrogram
There are certain situations where performing a hip arthrography, which is a type of X-ray procedure, is not advised. These include when there is an active infection in the hip joint, on nearby skin or tissues, or along the path the needle would need to take. An skin infection over the hip joint can spread to the joint space when the needle used in the procedure passes through the infected skin and into the joint.
Applying a contrast dye into the hip joint has similar issues to using the dye intravenously, or through your veins, like allergies to the dye and impaired kidney function. However, the risk of a bad reaction is lower when the dye is injected into the hip joint because less dye is used, and it’s absorbed into the body slower. If a person has had allergic reactions to contrast dye before, a plan should be established to prevent any problems during the procedure.
If a patient is prone to allergic reactions to contrast dye, steroids can be used to reduce the risk. If the person’s kidneys do not function well, the consequences of this injection will depend on how strong the dye is and how severe the kidney problem is. The bare minimum necessary amount of dye should be diluted with a saltwater solution in these cases. If a patient’s kidney function is suddenly worsening, the use of contrast dye is not recommended.
Equipment used for Hip Arthrogram
A hip arthrogram procedure is a medical process where a special dye, known as contrast, is injected into your hip joint. To keep everything clean and free of germs (which is referred to as a “sterile field” in medical terms), various items like skin cleansers, sterile sheets called drapes, gloves, syringes, and needles are used.
A specific type of needle, known as an 18-gauge spinal needle, is connected to a large syringe that acts as a storage space for the contrast. This syringe is connected to the needle with a length of tubing typically about 18 inches long. This setup makes it easier for the healthcare provider to adjust the position of the needle and make sure it goes in the right place during the procedure.
Contrast agents are pretty thick and can sometime blur the visuals of body structures, so it’s often a good idea to dilute them. This means mixing the contrast agent with a solution called sterile saline to decrease the concentration. Usually a half-and-half mixture of sterile saline and contrast agent is used.
Who is needed to perform Hip Arthrogram?
A children’s bone doctor, also known as a pediatric orthopedic surgeon, should be aware of the reasons for performing and not performing a special hip procedure called a hip arthrogram. This procedure involves examining the inside of the hip joint with an X-ray called fluoroscopy. The doctor should also be aware of any potential risks to the patient from this procedure. It’s important that these risks are thoroughly discussed with the child’s parents.
A radiology technologist, a health care professional with special training in taking medical images, plays a key role in this process too. They are responsible for making sure the child is safe while they get images taken for the hip arthrogram. These pictures will then be examined by both the radiologist, a doctor who specializes in reading these images, and the orthopedic surgeon.
Preparing for Hip Arthrogram
Before a hip arthrogram procedure, which is a type of medical imaging used to assess hip joint conditions, it’s important that parents of the child receiving the procedure are well-informed about the whole process. This is known as obtaining ‘informed consent’, which involves explaining the positives and negatives of the procedure, as well as other options that might be available. It’s also crucial to double-check which hip joint will be examined and review the child’s allergies and previous reactions to medication.
During the arthrogram, a needle is inserted into the hip joint. This is often done with the help of ultrasound, fluoroscopy, or CT scan for guidance. One common use of this procedure is examining cases of hip dysplasia in children. Hip dysplasia is a condition in which the ‘ball and socket’ joint of the hip doesn’t properly form in babies and young children.
The procedure involves the use of a special dye or contrast agent. The type of contrast used generally depends on the doctor’s judgement. But, the most commonly used types are low-osmolar nonionic monomer contrast media, which are usually better tolerated and have fewer side effects than other types of contrast media.
The contrast dose used in pediatric patients is usually 2 mg/kg for contrast-enhanced CT scans. However, the dose is often restricted by the size of the joint and is less than what is usually used for a CT scan. If more than one joint requires a contrast injection, it’s usually recommended that the total amount used is less than 2 mg/kg.
How is Hip Arthrogram performed
After being given a general anesthetic, your child will be placed flat on their back. This is to keep them calm and comfortable throughout the procedure. The medical team will clean and sterilize the hip area to minimize the risk of any infections.
To find the hip joint, the doctor will use their finger during the surgical procedure. This joint is positioned a little way to the side of the major blood vessel in the upper thigh (the femoral artery) and just below the ligament running from the hip to the groin area (the inguinal ligament).
A thin, long needle (22-gauge spinal needle) is then inserted into the hip joint using the help of a technique called fluoroscopy. This technique, using X-ray technology, helps guide the needle into the correct place. You might feel a slight resistance as the needle pushes past the joint coverings.
Once the needle is in the right place, a small syringe full of saltwater (saline solution) will be attached to it. This saline solution is then pushed into the hip joint. You’ll notice this becoming more difficult as the hip joint fills up and begins to bend due to the pressure. When the saline is released, it forces the syringe plunger back, showing that the joint has been correctly accessed.
The saline solution is then removed from the hip joint. During this process, the needle is kept in place. A syringe containing a mixture used for visibility during imaging tests (a contrast solution) is then prepared and connected with the help of medical tubes. The medical team will make sure there are no air bubbles in the syringe or tubes before they begin, as air bubbles could cause complications such as air emboli.
Once the needle is correctly located, the contrast solution is injected into the hip joint. This is done while watching the fluoroscopy monitor. After this, the needle is removed, and images are taken of the hip area while it is still in its natural position. The hip is then gently moved back into its normal place (reduced), and further images are collected. These pictures let your doctor check that the hip has been correctly positioned and is safe.
If both hips are being treated, the same steps are carried out on each side. Each hip is injected with the contrast solution and images are taken to ensure everything has been done correctly.
Possible Complications of Hip Arthrogram
While complications are rare with hip arthrography (a medical imaging procedure to view the hip joint), just like any procedure, some risks exist. These can include septic arthritis (a severe joint infection), allergic reactions, bleeding, reactions to the contrast dye used during the procedure, and potential damage to nearby structures.
There have been reports of complications when the procedure uses air in a double-contrast technique. To explain, this technique involves injecting air and a contrast dye into the joint to get a better image. In one noteworthy case, a patient experienced a life-threatening air bubble in their bloodstream, known as an air embolus, from air injected into the hip joint. This incident has led to recommendations against using air arthrography to confirm that the needle is in the joint properly.
Interestingly, a review study found one instance of death related to the double-contrast technique involving an air embolus injected during a hip arthrography. Because of these reports, using air in this technique is generally discouraged.
In order to prevent air embolus, it is crucial to properly release any present air from the intravenous tubing and syringe before injecting the contrast dye into the hip joint.
What Else Should I Know About Hip Arthrogram?
Hip arthrograms, a type of X-ray where a special dye is injected into the hip joint to give a clearer image, are a vital tool in accurately diagnosing and treating children’s hip issues. For example, in one study of children with developmental dysplasia of the hip (a condition where the hip joint doesn’t develop properly), 12 out of 21 treatment plans had to be changed based on the findings of a hip arthrogram. This special X-ray was also useful in confirming what doctors found during surgery, like a flipped over rim of cartilage in the hip joint (inverted labrum) and overgrowth of a certain hip ligament (ligamentum teres hypertrophy).
Another study looked closely at 72 hips with developmental dysplasia and found that hip arthrograms could easily show the shape of the limbus, a crescent-shaped piece of cartilage in the hip. According to common medical understanding, if the dye used in the arthrogram pools in one area of the joint less than 6 mm into the hip, it means the hip joint has been deeply repositioned. One study suggested that looking at the medialization ratio, which shows how much of the hip joint lines up properly, can help show how well the hip joint will fit and move. Their findings showed that the shape of the limbus and the medialization ratio can help predict the success of a nonsurgical treatment in repositioning the hip joint.
Another study looked into hip osteonecrosis, a condition where bone tissue in the hip dies due to lack of blood supply, following a nonsurgical treatment to reposition the hip joint. They wanted to see if using a hip arthrogram changed the chances of osteonecrosis. Results showed that the hip arthrogram helped identify soft tissue structures that were preventing a secure repositioning. In patients who had the nonsurgical treatment without using the arthrogram, 29% developed osteonecrosis. But in patients who had the treatment using the arthrogram, only 7.6% developed osteonecrosis.