Overview of Digit Replantation
When it comes to reattaching any part of the upper extremity (like a hand) after it has been amputated, the main goal is to maximize how well that part will function after the procedure, not just to ensure that it survives. The success of this called “functional outcomes” depends on a few important factors.
One of them is the anatomical characteristics of the amputated area. This includes where the amputation happened and how much damage was done to the arterial intima (the inner layer of the artery) and other soft tissues.
In addition to these, there are also patient-specific considerations that should be kept in mind. For instance, their age, occupation, and the cultural importance they associate with their hands can play a crucial role in determining the outcome.
Anatomy and Physiology of Digit Replantation
The point where a person’s limb is amputated depends on the area where the flexor tendon, a tissue that connects muscle to bone, is injured. The areas of flexor tendon injury are categorized based on their relation to the flexor digitorum profundus, a muscle in the finger that helps with flexible movements. These areas or ‘zones’ also consider factors such as the location of the carpal tunnel, a passage in the wrist, and parts of the finger like the digital pulley system and the flexor digitorum superficialis tendon.
Let’s break down the five different zones. Zone 1 injuries are those where the cut happens at a part further than the starting point of the flexor digitorum superficialis tendon. Zone 2 injuries happen between the ending point of the flexor digitorum superficialis and a part called the A1 pulley, which is slightly above the joint connecting the hand with the finger. Zone 3 injuries or amputations occur between the A1 pulley and the end of the carpal tunnel in the wrist. Injuries going through the carpal tunnel are considered as zone 4 injuries. Lastly, Zone 5 injuries occur before the start of the carpal tunnel.
Zone 1 amputations only involve the deep flexor tendon of the fingers, which allows the next joint in the finger to still move. These types of amputations generally lead to positive outcomes. However, if the amputation happens towards the far end of the middle phalanx or after the joint at the finger’s far end, the small size of blood vessels in the fingers may make reattachment difficult. Amputations in zone 2 historically have challenging outcomes due to the complex structure of the finger, but this doesn’t mean reattachment should not be considered for certain patients.
Overall, results of reattachment, in zones 3 to 5, really depend on other factors related to the injury and the patient’s overall health, such as the length of time the amputated part has been without blood, the way the amputation happened, and any existing health conditions the patient has, rather than the point of amputation.
Why do People Need Digit Replantation
Upper extremity replantation is a surgery that reattaches a part of your arm, hand, or fingers that have been amputated, or cut off. This type of surgery might be needed if you have had an amputation in the following areas: your thumb, multiple fingers, the palm of your hand, a single finger lower than where the flexor digitorum superficialis tendon attaches (a tendon in your hand that helps with finger movement), sharp amputations at the hand, forearm, or elbow level. Kids who have any type of amputation might also need this surgery.
Not everyone who has had an amputation will need this type of surgery. Usually, a hand surgeon at a major trauma center or a facility that can do replant surgeries will look at your injury and decide if the surgery is right for you. This approach ensures that patients are transferred to these facilities only when necessary and that the transfer is worthwhile.
When a Person Should Avoid Digit Replantation
There are certain situations when it’s not safe to reattach a severed finger. These situations include:
If the injury to the finger is very severe because of a crushing or tearing, it might not be possible to do the surgery. Also, if there are injuries in many places on the finger, this can make it more complicated.
The surgery may not be possible if the finger was cut off above where a certain tendon (the flexor digitorum superficialis) attaches. Tendons are like ropes inside your hand that help your fingers bend. If the finger was cut off too high on the tendon, it might not be possible to reattach it.
If it’s been a long time since the finger was severed, this can also make reattachment harder. This is because the tissue in the finger might have started to die because it’s not getting any blood.
Finally, if the patient is not stable, either mentally or physically, it might not be safe to do this surgery.
If these situations apply to a patient, then there is no urgent need for them to be transferred to a hospital that can do the finger reattachment, as long as their injury can be managed at the hospital they’re currently at.
Equipment used for Digit Replantation
Reattaching a finger needs the use of a special microscope used during surgery, as well as the correct tiny surgical tools and stitches. If these specific items aren’t easily available at the hospital treating the patient, it may be necessary for the patient to be moved to a different hospital that has all the necessary equipment.
Who is needed to perform Digit Replantation?
Reattaching a finger (or “digit replantation”) is a delicate job that requires a well-trained surgeon who is familiar with a special technique known as microsurgery. Commonly, this could be an orthopedic or plastic surgeon. However, this type of surgery not only requires a skilled surgeon, but also special equipment and medical professionals who know how to use it. Not all hospitals or medical centers may have these resources.
Surgeons who work specifically with bones and muscles (orthopedic), appearance or reconstruction (plastic), or general surgery and also have a special certificate in hand surgery are usually the best people to do this type of procedure. If your local hospital does not have the necessary resources, these surgeons can also guide you to places where you can safely have your finger reattached.
Preparing for Digit Replantation
If a body part gets amputated, it’s extremely important to transport it properly in the hopes of reattaching it. The best way to preserve it for transportation is by wrapping the part in a bandage that’s been soaked in a special liquid (like normal saline or lactated ringers), then place it inside a plastic bag, and put that bag on ice. But never put the part directly on ice, as it can cause freeze burns or other injuries to the tissue. If this happens, doctors may have difficulty reattaching the part, or the function of the reattached part might be compromised.
Time is a very crucial factor when it comes to surgery to reattach the lost part. The window of opportunity for reattachment depends on the amount of muscle present in the amputated part. Finger amputations are an example where there is no muscle and the tissues present can survive on their own for up to 12 hours under normal conditions and up to 24 hours if cooled. However, for parts with a significant amount of muscle tissue, like a forearm or an elbow, the maximum time until reattachment surgery should be no more than 6 hours under normal conditions or up to 12 hours if cooled. Sometimes, to buy this time, doctors temporarily redirect blood flow to the detached part before they even start the reattachment surgery.
How is Digit Replantation performed
If an unfortunate accident results in a body part becoming severed, such as a finger, the amputated part should be brought to the operating room even before the patient. This allows doctors to clean it thoroughly and examine under a microscope to see the quality of the tissue, including nerves and blood vessels. This helps decide if the part can be reattached successfully. During this examination, any recognizable parts are marked with stitches or tiny chips for easy identification.
The process of reattachment, known as replantation, follows a specific order. It begins with shortening and fixing the bone in the severed part. This step is crucial as it eases tension on the surrounding soft tissues, which are repaired later. For children, care is taken not to affect the “physis” – the growing part of a child’s bone.
After fixing the bone, the next step is the repair of the “extensor tendon”, a tough band of tissue that helps extend or straighten the body part. This repair is followed by fixing the “flexor tendon”, which opposes the extensor helping to bend the body part.
The focus then shifts to fixing the artery – a blood vessel that takes blood away from the heart. Making sure the artery is working properly again is crucial for the success of the replantation. Sometimes, this might require the use of vein grafts – replacing damaged portions with a healthy vein – if the artery is excessively damaged. Surprisingly, we have an abundant supply of these replacement veins in the same limb, but sometimes doctors may need to use veins from the leg.
After arterial repair, the doctor will then repair the nerves, which are essential for feeling and movement. Repairing the vein, which returns blood to the heart, comes next. Finally, the doctor will repair “soft tissue”, the tissues that surround and support organs and body structures.
So, here’s the sequence in which a doctor typically repairs an amputated body part:
- Bone
- Extensor tendon (helps extend the body part)
- Flexor tendon (helps bend the body part)
- Artery (carries blood away from the heart)
- Nerve (helps in sensation and movement)
- Vein (returns blood back to the heart)
- Soft tissue (surrounding and support structures)
Possible Complications of Digit Replantation
Injuries to the flexor tendons in the hand can cause several problems. These may include bleeding, infections, failure of the injured part to reattach, and stiffness in the finger. A common issue is blood pooling in the finger because repairing damaged blood vessels on the back of the hand can be challenging.
Doctors use various methods to prevent or treat this blood pooling, such as removing the fingernail, making small incisions in the fingertip and applying a medication called heparin, or using leeches. Leech therapy might sound unusual, but it’s a trusted method used by medical professionals. However, patients undergoing leech therapy need to take an antibiotic named ciprofloxacin. This medication helps prevent an infection caused by a bacteria called Aeromonas hydrophilia.
What Else Should I Know About Digit Replantation?
If your doctor is experienced in microsurgery, the success rate of reattaching a severed body part, like a finger or hand, is usually around 80%. How well you can move that body part after surgery depends on where the cut happened, how the cut happened, and how well you stick to your physical therapy after surgery.
Your doctor will likely tell you before surgery that the movement in the reattached body part may only be about half of what it was before. So, if it’s a finger, you might only be able to bend it halfway compared to before. Also, after surgery, people usually have to stay in the hospital for around ten days and may need to take about 7 months off work or their regular activities to fully recover.
The best outcomes are usually seen when the thumb, hand, part of the forearm closest to the hand, and fingers closer to the palm (an area known as “zone 1”) are reattached.
