What is Hand Extensor Tendon Lacerations?
Cuts to the extensor tendons, which are the tissues that help straighten the hand, are fairly common injuries. If these types of injuries aren’t properly treated, they can lead to long-term issues with hand movement. These tendons, located near the surface of the hand and close to the bones, are more likely to get injured than the flexor tendons, which help bend the hand.
What Causes Hand Extensor Tendon Lacerations?
Extensor tendon injuries, which are cuts or tears to the tendons that straighten your fingers, are often seen in young people who do manual work. These injuries can happen in a few ways, but they are most commonly caused by cuts from sharp objects or from saw accidents.
The way the injury happens can also affect where it occurs on your hand. For example, if you injure your hand with a saw, it’s more likely to occur further down your hand, past the main knuckle of your hand (also known as the metacarpophalangeal joint or MCPJ), and these injuries could also come with broken bones. On the other hand, cuts from sharp objects often happen nearer to your wrist, on the side closer to your body.
These injuries can also occur in children, although they’re not as common. Both the tendons that bend (flexors) and straighten (extensors) the fingers can be injured. Very rarely, these injuries can happen to newborns during birth, especially during C-sections. This is known as an iatrogenic injury, which means it is an unintentional harm caused during medical treatment or procedures.
Risk Factors and Frequency for Hand Extensor Tendon Lacerations
Extensor tendon injuries typically affect working-age men, often in their thirties, and can have a significant economic effect. In the United Kingdom alone, these injuries account for over £100 million per year in direct care costs. This number jumps greatly when considering lost wages and productivity. The most common hand affected by these injuries is the dominant one, particularly the thumb. However, the index and middle fingers can also be injured, and these types of lacerations can happen anywhere.
- Men in their thirties, particularly those who are working, are most affected.
- In the UK, these injuries cost over £100 million per year in direct care. The cost is much higher when considering lost wages and productivity.
- The dominant hand is usually the one that gets injured, particularly the thumb. But the index and middle fingers could also be affected.
- These injuries can happen anywhere.
- In the UK, these injuries make up 30% of all emergency department visits.
- In the United States, they make up over 25% of all soft tissue injuries.
Signs and Symptoms of Hand Extensor Tendon Lacerations
Proper assessment and treatment of hand injuries is extremely important because they can significantly impact someone’s daily life and work. When examining an individual with a hand injury, it’s important to know how they were injured, what position their hand and fingers were in when it happened, their age, job, and whether they’re right or left-handed. It’s also important to know if a human bite was involved because this can cause an infection and would require more extensive cleaning of the wound. A thorough examination of both hands is necessary, comparing the injured hand to the healthy one.
If the hand injury is severe or part of a greater trauma, the individual should be treated according to a trauma care protocol. The medical professional should start by looking at the hand to check for any visible injuries. Injuries to the back of the hand could indicate damage to the tendon that straightens the fingers. Before giving any local anesthetic, the doctor should check the pulses, sensory function, and movement, which can indicate the health of the nerves and blood vessels in the affected area.
After these initial checks, any open wounds need careful examination under local anesthetic and magnification. The medical professional needs to look for additional injuries. Any wound that appears deep might need to be evaluated by a hand surgery specialist. The doctor needs to check the function of the nerves that affect hand movement, particularly the radial, median, and ulnar nerves. The tendons that aid in extending the fingers and thumb can be divided into two main groups:
- Superficial Extrinsic Extensors:
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor digitorum communis
- Extensor digiti minimi
- Extensor carpi ulnaris
- Deep Extrinsic Extensors:
- Abductor pollicis longus
- Extensor pollicis longus
- Extensor indicis proprius
In addition to these groups, the tendons at the level of the wrist are compartmentalized into 6 compartments. Each digit can be moved independently and should be tested individually to assess the active range of movement and movement against resistance. Additionally, tendons have been divided into zones based on the underlying bones and joints. Damage to these areas may require specialized treatment depending on the zone affected.
Testing for Hand Extensor Tendon Lacerations
If you’re being evaluated for a suspected injury, the first thing your doctor will do is thoroughly examine the injured area. They will use x-rays to check for broken bones and the presence of other foreign materials like glass.
The doctor will take three different kinds of x-rays: a straight-on view (anteroposterior), a side view (lateral), and a side-angled view (oblique). These images will cover not just the injured area, but also the joints close to it.
If your injury is complex and involves significant damage to your tissues or bones, you may need some kind of reconstructive surgery. This goes beyond just repairing the affected tendon and isn’t covered in this piece. However, before deciding on any treatment plan, a detailed analysis of your condition will be conducted. The doctor will follow some basic steps to manage your injury:
- Ensure that blood supply to the affected area is adequate
- Prepare the wound for healing (a process also known as debridement)
- Make sure that your bones are secure and stable
After these steps are completed, the doctor can look at fixing the damaged tendons and consider if grafting or the use of tissue flaps is necessary for your recovery.
Treatment Options for Hand Extensor Tendon Lacerations
When it comes to treating extensor tendon injuries (also known as cuts or tears to the tendons at the back of your hand that help straighten your fingers), there’s no one-size-fits-all approach. It’s crucial to remember that the term ‘laceration’ can often refer to various types of injuries that may be more complicated than a simple cut.
The initial steps usually involve considering tetanus injections for prevention and the use of antibiotics. Attempting to repair the injured tendon should ideally occur within a week, but definitely within two weeks of the injury.
The repair process might include direct repair of the tendon, using a graft (donor tendon), or even a tendon transfer. The more tissues damaged from the injury, the harder it can be to restore normal hand function. It’s vital to maintain or restore the correct length of the tendon during this process, as any minor changes can have negative effects on finger movement.
Surgery might be necessary under certain conditions, such as if a significant portion of the tendon is cut, the patient cannot straighten their digit, the wound is contaminated and requires thorough cleaning, the joint is unstable, previous non-surgical attempts have failed, and the patient can follow the post-surgery care plan.
Different areas of the hand call for different treatment approaches. For instance, for cuts near or beyond the last joint of the finger, the skin and the injured tendon could be stitched simultaneously. If there’s no associated bone injury, these injuries can be treated right away, provided the joint is thoroughly cleaned.
Injuries on the middle part of the finger involving less than 50% of the tendon may be treated with 1 to 2 weeks of wearings a splint, provided the joint can be extended against resistance.
It’s important to note that more severe injuries, contamination, and complications from the injury could require additional treatment methods, could delay treatment, or could result in less than ideal outcomes.
In any case, timely and appropriate treatment, patient compliance with the treatment and post-treatment protocols, and a thorough evaluation of the injury (such as using the Miller’s criteria) all play a significant role in the recovery process.
What else can Hand Extensor Tendon Lacerations be?
The word ‘laceration’ suggests a specific type of injury, but other conditions can also cause a similar difficulty with extending the fingers. These can include:
- Mallet finger: This is caused by the tearing away of the extensor tendon – which allows you to straighten your finger – from the very end of the finger, sometimes taking a piece of bone with it.
- Arthritis: Long-term irritation to the tendon can damage the structure that helps extend the fingers, leading to well-known deformities like boutonniere or swan neck, or even a simple tendon tear near the affected joint.
- Trigger finger: This condition causes a loss of both automatic and voluntary finger extension.
- Posterior interosseous nerve syndrome: People with this condition can’t extend their fingers on their own, but normal movement can be preserved with surgical intervention.
It’s essential to identify the specific cause in order to determine the most effective treatment.
What to expect with Hand Extensor Tendon Lacerations
These types of injuries are common due to the size of the population, and treatment often aims to get people back to work as soon as possible. Overall, the results of treatment are usually better when the injury occurs closer to the body, rather than further away, because the tendons have more room to move and heal.
Recovery also depends on how quickly the injury is treated after it happens. People who receive treatment within five days typically regain nearly all of their normal range of motion (the ability to move a joint fully and freely). Specifically, they regain about 97.8% of the normal movement of their other, uninjured limb, while those treated after five days regain about 89.5% of normal movement.
Children tend to recover from these injuries more quickly and successfully than adults, often regaining their full range of motion even if they have to remain still for a long time. Their rehabilitation and recovery stages are typically better and they generally achieve excellent results with only a few complications.
Possible Complications When Diagnosed with Hand Extensor Tendon Lacerations
When someone injures the tendons on the back of their hand, different complications can develop:
- Tendon rupture: The tendon, or tissue connecting muscle to bone, breaks away completely.
- Reduction in both active and passive motion range: Difficulty or limitation in moving the hand both voluntarily and involuntarily.
- Adhesions: Scarring that connects tissue that should not be connected.
- Extension lag (especially in main joint of the hand): Difficulty or inability to fully straighten the hand.
- Loss of flexion and reduced ability to grip: Difficulty or inability to bend the hand or fingers to hold objects.
- Finger deformities: Changes in the normal shape of the fingers.
- Swan neck deformity: A condition that usually occurs due to prolonged bending of the endmost joint of the finger and slight dislocation of tissue bands, resulting in the middle joint of the finger bending backward.
- Boutonniere deformity: In this condition, a finger is bent downward at the middle joint and bends backward at the last joint; this usually occurs due to an injury to the central part of the finger – the central slip – and slight dislocation of the tissue bands on the underside.
The most common complication is adhesions, or scar tissue, that can cause limited finger bending. This is a bigger problem, especially at certain zones of the hand, because it can significantly affect one’s grip. In such cases, intense hand therapy or sometimes even a second surgery to release the adhesion (called tenolysis) may be required. The chances of needing a tenolysis range between 0 and 17%, while the chances of the repaired tendon rupturing again range between 0 and 8%.
We can measure how well a person recovers from such an injury using Miller’s criteria. This scales range from ‘excellent’ (no lag in straightening or loss in bending), to ‘good’ (less than 10 degrees lag in straightening, and less than 20 degrees loss in bending), to ‘fair’ (between 11 and 45 degrees lag/loss) and ‘poor’ (greater than 45 degrees lag/loss). The extent of these complications decides the recovery outcome.
Recovery from Hand Extensor Tendon Lacerations
Following surgery for repairing a tendons, a specific regimen is followed to prevent the tendon from moving too much while also avoiding the formation of troublesome adhesions that can limit movement. There are generally three methods of post-surgery care when it comes to lacerations on the extensor tendon, or the tendons that help us extend our hands and fingers. These methods are immobility (not moving the injured part at all), early passive motion (movement starts sooner after surgery), and early active motion (the patient begins to move the injured part as guided by a therapist).
Typically, the practice was to keep the injured part completely immobile for 4 to 6 weeks after surgery. However, this method often led to patients losing some flexibility due to the formation of adhesions, which are bands of scar-like tissue that form between tissues and organs. Immobilization might be appropriate for patients who can’t control their movements but it has the highest rate of complications. When treated this way, only 64% of patients experienced good to excellent results, with a noticeable loss of motion in most cases. This can partially be solved by reducing the time the patient remains immobile.
For children, immobility might be preferable since it doesn’t rely on them controlling their movements and they also don’t get complications common among adults like adhesions, tissue shrinkage (contractures), misaligned tendons (bowstringing), and misplaced tendons (tenodesis). Most complications in kids after surgery relate to damage at the repair site rather than not moving enough.
Studies show that dynamic splints, splints that allow controlled and minimal movement, lead to much better recovery in the case of extensor tendon injuries. However, some of these early passive motion splints can be expensive and uncomfortable to wear, so they do require a motivated patient. Generally, doctors encourage early active movement after surgery as it has been found to be more cost-effective and has a lower rate of complications.
Nowadays, splints are made such that they allow just the right amount of movement to prevent stiffness, but not so much that it damages the repair. A relative motion splint is a smaller kind of splint that is designed in such a way that the injured tendon moves less compared to the nearby tendons. This has been proven to work well with extensor tendons in particular regions of the hand and wrist. Protected movement early after surgery led to 90% of patients recovering well, even if they weren’t quite able to follow the recovery protocol perfectly.
Preventing Hand Extensor Tendon Lacerations
These types of injuries are always caused by accidents, so preventing them largely involves using tools and equipment safely, from kitchen utensils to work machinery. After an injury occurs, it’s crucial for patients to understand and follow the recommended recovery plan. This will help them heal as effectively and efficiently as possible.
