Overview of Osteocutaneous Radial Forearm Flap
The radial forearm free flap is a type of medical procedure that was originally introduced by Dr Yang and Dr Gao in the early 1980s and is now widely used. In simple terms, it’s a versatile technique that allows doctors to use skin, fat or even some bone from the forearm to repair other parts of the body. Many studies highlight this method’s effectiveness, especially for surgeries within the mouth.
One way this process is used is in what’s known as an osteocutaneous radial forearm free flap. This is when a small amount of bone is also collected from the forearm and used for reconstruction in other parts like the head, neck, or face structure. It’s a useful option if some bony reconstruction is required.
In this specific technique, the useful part of the forearm (known as the “flap”) is kept well-supplied with blood by maintaining the connection to certain blood vessels. This technique isn’t the only option; there are alternative methods that use bone and skin or fat from other areas (like the fibula in the leg, the scapula in the shoulder, or the iliac crest of the hip).
So what makes the osteocutaneous radial forearm free flap so advantageous? Some of the main benefits include the thin, flexible skin from the forearm, the long connecting blood vessel, and the reliable structure of the blood vessels in the forearm. Despite these benefits, it also has its downsides. The main drawback relates to the surgical site on the forearm (where the “flap” is taken from), as this can result in bone breakage risks and reduced strength and function of the wrist.
This method’s usefulness depends on understanding the procedure in detail, and considering its risks and benefits. That information can help doctors make informed decisions about whether this technique is the best choice for each individual patient’s needs.
Anatomy and Physiology of Osteocutaneous Radial Forearm Flap
The blood supply for a certain type of skin graft called the osteocutaneous radial forearm flap hinges on the radial artery. This artery, alongside the ulnar artery, comes from a pair of arteries called the brachial artery located in the pit of your elbow, the antecubital fossa. Doctors make sure not to take the artery from any area higher than this bifurcation, or branching off, to keep the lower half of the arm safe. The radial artery, on average, has a diameter of 3 mm at this point and tends to be anywhere between 14 and 22 cm long in an adult.
This graft is placed in a groove between the brachioradialis muscle and the flexor carpi radialis muscle. This area is known as the lateral intermuscular septum.
The numerous blood vessels supplying nutrients to the skin and bone of this flap originate from the radial artery. It’s crucial not to damage these passages during the operation as they provide the necessary nutrients to the harvested bone.
Choosing the patient for this procedure depends heavily upon how well the hand and fingers can survive with only the ulnar artery supplying blood. If ulnar artery flow alone is sufficient for the hand’s needs, the radial artery (which terminates in the wrist before becoming a part of the deep palmar arch) can be used for this type of flap.
Different tests, such as the Allen test, can assess whether the ulnar artery alone can feed the hand and fingers sufficiently. During this test, the patient clenches their fist while the doctor compresses the arteries in the wrist. When the patient opens their fist, the doctor releases the pressure on the ulnar artery while continuing to compress the radial artery. If the hand returns to its normal color within five seconds, this suggests the ulnar artery can alone supply blood to the hand.
Venous drainage, or the return route of the blood back to the heart, is provided by veins that travel with the radial artery. This system allows for either one single or two independent drainage systems to be used in the neck, depending on what is most suitable for the patient.
While performing the operation, it’s crucial to identify the sensory nerve that provides feeling to the thumb and the back of the hand, to prevent discomfort after the surgery. There are also nerves that provide feeling to the forearm. Those are usually removed as they belong to the skin removed during the operation, but they could potentially help the grafted skin have sensation.
While a large piece of skin can be taken, doing so would significantly alter the natural flow of lymph (a clear fluid that is part of the immune system) from the hand. To prevent swelling in the hand, a strip of skin should be preserved. If the flap being harvested includes bone, the cut should be made slightly higher to avoid complications, like issues with the hardware used to stabilize the bone after the surgery.
One downside of undergoing this procedure is discomfort at the site of the harvest. The radius, one of the two bones in the forearm, is important for wrist and hand function. The length of the bone that can be harvested is limited, but if necessary, a muscle connected to the radius can be released to gain more bone length. However, doing so increases the chance of postoperative discomfort. Hence, decisions like these are taken on a case by case basis.
Why do People Need Osteocutaneous Radial Forearm Flap
The osteocutaneous radial forearm free flap, also known as OCRFFF, is a type of medical procedure most commonly used in rebuilding parts of the jawbone (the mandible and maxilla). This might become necessary due to injuries, cancers, or other conditions that damage or remove part of the jaw. But there is a limit to the amount of bone that can be harvested from the forearm, so this procedure is usually used for smaller, shorter parts of the jawbone.
However, the bone taken from the forearm is usually thin, so it has its limitations. For example, the thin bone makes it difficult to place dental implants. The forearm bone can also be used to repair bone in arms or legs, but its thinness may limit its use in those areas too.
Besides jaw and limb repair, OCRFFF has been used in other types of surgeries: including to rebuild the nose (nasal reconstruction), the forehead sinus (frontal sinus reconstruction), and the airway. Recently, it’s also been used in the construction of a penis (phalloplasty).
When a Person Should Avoid Osteocutaneous Radial Forearm Flap
Microvascular surgery is a delicate process that is often used to repair tissues in our body by manipulating tiny blood vessels. Specific patients being considered for a procedure known as osteocutaneous radial forearm free flap (OCRFFF) reconstruction might not be suitable due to several reasons. This procedure uses skin, bone, and blood vessels taken from the arm to reconstruct and repair other parts of the body. However, some conditions might make it unsafe for these patients to go ahead with the surgery:
1. High risk of serious injury to the lower part of the arm if the only blood supply comes from the ulnar artery, one of the two main arteries in the forearm.
2. A high chance the flap taken from the arm might fail if the radial artery, another main artery in the forearm, is not sufficient.
3. The body parts receiving the transplanted tissue need to have good quality blood vessels. If this is not the case, then the surgery cannot be performed.
4. The repair can’t be completed if it requires more than 10 to 12 cm of bone from the arm.
5. The procedure cannot be performed if there is a need to place dental implants into the bone that has been transferred.
The OCRFFF procedure involves using the radial artery in the arm. If this artery is damaged due to injury, profound peripheral vascular disease (a condition that restricts blood flow to arms and legs), arterial agenesis (absence of artery), or due to clots in the blood, this could prevent the OCRFFF procedure. In other words, if the artery that supplies blood to the arm is not up to the task, then it makes it unsafe to proceed with the surgery.
When it’s possible to perform the procedure, the area that is going to receive the transplanted tissue must be healthy enough. Multiple arteries in the neck are suitable for this kind of surgery. But if the neck doesn’t have enough of these arteries, other options need to be considered, for example, a specific artery in the chest. And, if the case is too severe, it might be better to avoid this type of surgery altogether and favor a different approach.
The size and quality of the bone that is harvested or extracted are also important considerations. Recovery is more difficult if more than 10 to 12 cm of bone is required, such as in the case of replacing the entire lower jaw. When large bone pieces are needed, another procedure using tissue from the lower leg might be recommended instead – but that also depends on that person’s blood supply to their foot. Medical complications such as conditions caused by smoking, old age, and other illnesses can make sufficient blood flow a concern.
Previous injuries and surgeries to the wrist might make the process more complicated. The hand that is not used for writing is usually preferred for the procedure, but sometimes, due to blood flow considerations, the other hand might need to be used. Jobs and hobbies that require manual dexterity might also be a reason to think twice before proceeding with this procedure.
Some health issues might increase the risk of failure for these procedures. Examples include severe peripheral vascular disease, blood clotting disorders, and heart disease. Patients with a condition called factor V Leiden thrombophilia (a disorder that increases the risk of blood clots) are also at a higher risk of the procedure failing due to clotting. Smoking increases the risk of failure in this type of surgery as well. Despite this, many patients with these conditions have undergone successful microvascular reconstructive procedures.
Cancer patients with multiple severe health issues might not be well enough to withstand this long and complicated surgery and may consider other options instead. For patients with multiple health issues, the risks and benefits of microvascular reconstruction may need to be assessed against less optimal but lower-risk reconstructive options.
Equipment used for Osteocutaneous Radial Forearm Flap
The doctor will need a specific set of equipment to carry out the operation:
* A soft tissue set, which includes tools designed for surgical procedures involving your body’s soft tissues, like muscles and fat.
* A microvascular set, a collection of tools needed for microvascular surgery – it’s a procedure that involves the repair of tiny blood vessels and nerves.
* An operating microscope, which is a special type of microscope that allows your doctor to see very small areas clearly during surgery.
* Instruments the surgeon prefers to use for osteotomy, a procedure used to cut and reshape your bones.
* A tourniquet, which could be used to control or stop excessive bleeding during the operation. However, this is optional.
* Instruments aimed at protective plating of the radius – the bone in your forearm on the thumb side. Doctors strongly recommend this because it offers additional safety during your recovery.
Who is needed to perform Osteocutaneous Radial Forearm Flap?
The team for this operation includes a main doctor who is the surgeon, one or two other doctors who assist, a nurse who helps with equipment and medications in the operating room, a medical professional who has trained to assist in surgery, and a doctor called an anesthesiologist who will put you to sleep for the duration of the surgery. It is important that this anesthesiologist has experience with very precise surgeries that can take a long time.
Preparing for Osteocutaneous Radial Forearm Flap
Preparing a patient for surgery usually starts with putting them to sleep using general anesthesia and ensuring their airway remains open safely. With the patient asleep, doctors can safely take a piece of tissue, called a “flap,” from one part of the body.
Before this though, doctors perform something called an Allen Test. This test checks the blood flow in the hand of the arm where the tissue will be taken. The test involves raising the arm and pressing down on two arteries in the wrist to stop the blood flow. The doctor then releases one of the arteries and checks how quickly the hand returns to its normal color. A quick return to normal color means there is good blood flow. This test is best done when the patient is warm; if the patient is cold, the hand’s blood flow may appear slower than it actually is.
Doctors may also use a tool called a Doppler to help with the Allen test. This device helps to measure blood flow and can confirm the results of the Allen test. If the Doppler, however, shows that the blood flow in the hand is mainly through one artery, the procedure of taking the tissue might need to be stopped and another method considered.
Once these tests are done, the patient is then positioned for the surgery. Most commonly, the patient lies flat on their back with their head raised slightly. The arm from which the tissue is to be taken is stretched out on a special board.
Before starting the surgery, a tourniquet (a band wrapped tightly around an arm or leg to control bleeding) may be applied. The tourniquet can be put on in a clean or sterile manner, depending on the situation. If the tourniquet is put on in a non-sterile manner, it is covered to prevent contamination of the surgery area.
Finally, the patient’s arm and surgical site are cleaned thoroughly. Antibiotics might also be given before the surgery starts, to reduce the risk of infection. The exact type and amount of antibiotics would be decided by the surgeon.
How is Osteocutaneous Radial Forearm Flap performed
This procedure involves operations on the arm, which may be done using a tourniquet (a device to stop blood flow). Surgeons may prefer to perform the procedure with the arm drained of blood, using a tourniquet set to a specific pressure for no more than 2 hours. An Esmarch wrap can be used to drain the blood from the arm before the tourniquet is applied if preferred.
The surgical area is designed around the radial artery (an artery on the underside of your arm). A skin flap is created and placed on an island by cutting through the skin and fat around it until the forearm muscles’ lining is visible. The muscles on the inside and outside of the forearm are identified, and dissection is carried out along the sides of these muscles.
The skin flap is also incised along the top and bottom. Care is taken during this process not to damage certain vessels. The vein may be preserved to aid in draining the flap, which is a part of tissue that has been surgically moved from one part of the body to another.
A lazy-S incision (an S-shaped cut) is made from the top of the skin flap to the pit of the elbow. The flaps are lifted over the lining of the muscles on either side of the forearm. The radial artery and additional vessels that supply and drain the flap are exposed and isolated by tying off their smaller connections along their length. It’s important to maintain these deep vessels that may supply blood to the radius (a bone in the forearm).
If there’s any concern about the lower arm’s viability, an Allen test can be performed. This test involves using a special type of clamp on the radial artery at the wrist and releasing the tourniquet, showing the impact of blood flow from the ulnar artery only. If there’s a suggestion of blood shortage, the flap procedure is stopped. If the arm can get enough blood from the ulnar artery alone, the procedure can continue by tying off the radial artery. The flap is then lifted off the tendons of the forearm. Care is taken to keep the lining of the tendons intact to prevent the tendons from sticking to the skin graft after the operation.
The arm’s bone can then be harvested for grafting. Several steps are taken to expose the bone and then remove a piece of it. Care is taken not to cut the remaining radius, which could weaken it. Once this is done, the flap can be lifted out of the forearm, with the vessel bundle feeding it in place.
The arterial and venous anatomy is then defined before ligation (a process of binding or tying off blood vessels) and the start time for the tissue without blood flow is marked. The details of the vessel connections determine where they can be taken and ensure there is sufficient length and size for the anastomosis (a surgical connection between blood vessels).
Once the flap is ready to be moved, the donor vein and artery are tied off, and the flap’s blood flow is stopped. The flap is then placed according to the planned reconstruction, and the surgical connection of the blood vessels is performed.
It is highly recommended to place a plate on the radius after this type of procedure as the process of harvesting the bone significantly weakens it. This provides extra support and reduces the risk of a fracture.
Possible Complications of Osteocutaneous Radial Forearm Flap
The forearm free flap surgery, where skin and muscle are moved from the arm to another part of the body, is quite a reliable procedure with a high success rate. Even when a small segment of arm bone is included in the process, the success rate remains largely unaffected.
As with every surgery involving the reattachment of tiny blood vessels, there’s a risk of the newly attached section, or flap, not getting enough blood supply. This is called flap failure. The surgeon’s expertise, how the surgery is done, and the shape of the blood vessels play a part in the success or failure of the surgery. Flap failure can occur if the blood flow gets blocked due to vessel twists or if there is too much tension. Careful placement of the flap is especially crucial for surgeries in the mouth to avoid problems from saliva leakage.
Despite the best planning and careful surgery, some patient-specific factors could still lead to flap failure. Avoiding these situations and catching signs of flap failure early on can help fix a problem or avoid complications that may require another reconstructive surgery.
In the procedure where a small segment of arm bone is used, complications can occur, such as fractures, improper healing, insufficient bone, or bone shrinkage over time. Moreover, there’s also a risk of complications from surgical implants, slow wound healing, or wounds reopening.
In some rare cases, using the skin and muscle from the forearm can lead to reduced blood flow to the hand. Tests are carried out before and during the surgery to prevent this from happening. There’s also a risk of damage to the nerve in the forearm, resulting in painful lumps called neuromas. The wound where the flap was taken might be closed with a skin graft (transplant), which the patient might not find aesthetically pleasing. Sometimes, skin grafts may not be successful due to blood accumulation, exposed tendons, poor wound healing, or infections. Also, during the procedure, careful attention must be given to avoid damaging the forearm muscle, which could lead to tendon exposure or injury.
The more specific complications with this type of surgery can involve losing strength in the arm due to some of the radial bone (part of the forearm) being used. This increases the risk of the radius bone fracturing. To reduce this risk, the remaining radius can be reinforced with metal plates, although these can also become infected. However, these complications are very rare.
Few studies compare this forearm skin and muscle transfer surgery to other similar procedures. One study concluded that while there were more healing delays and a higher chance of chronic pain or dissatisfaction with scar appearance, there were minimal impacts on daily functions or activities. This surgery may not always be the best option depending on individual circumstances, but it provides a valuable tool for reconstructive surgeons.
What Else Should I Know About Osteocutaneous Radial Forearm Flap?
A forearm free flap, specifically the radial forearm free flap, is a popular way to reconstruct parts of the head and neck. For those who are unfamiliar, this involves taking a segment of the bone from the forearm (the radius) and using it to reconstruct the affected area. It’s a flexible method that reconstructive surgeons often use to rebuild parts of the body.
This type of surgery is seen as an alternative to other kinds of ‘free flap’ operations that borrow bone from different parts of the body such as the fibula (leg), scapula (shoulder blade), and iliac crest (hip bone).
It’s important for both the patient and the surgeon to understand the pros and cons, as well as any potential complications of each type of operation. This understanding helps in setting realistic expectations and achieving the best possible results from the surgery.
