What is Finger Dislocation?
Finger joint dislocation is a typical injury that can happen in different parts of the hand. The dislocation can happen in the proximal interphalangeal (PIP), distal interphalangeal (DIP), or metacarpophalangeal (MCP) joints. This article covers the occurrence, structure, check-up, imaging, treatment, and potential complications of finger dislocation.
Each finger has three joints: the MCP joint, the PIP joint, and the DIP joint. The MCP joint is the junction between the metacarpals and the initial part of the fingers (proximal phalanges). The PIP joint works like a hinge and connects the first and middle parts of the fingers (proximal and middle phalanges), while the DIP joint, also a hinge, connects the middle and end parts of the fingers (middle and distal phalanges). The flexibility of these joints allows our fingers to bend and straighten, which helps them to grab, pinch, and reach for things. A lot of the finger’s flexibility comes from the PIP joint.
The finger joints are supported by stabilizers, which are essential for finger movement. Stabilizers can be non-moving (static) or moving (dynamic). Non-moving stabilizers are made up of tissue that doesn’t contract, which includes different kinds of ligaments, like the volar plate, which prevents overextending of the finger joints. The moving stabilizers, on the other hand, include tendons and muscles, an example of each being the central slip and lateral bands which help in straightening the PIP and DIP joints, respectively. Lastly, you can find digital arteries and nerves at the base of the finger, both on the inner and outer sides.
What Causes Finger Dislocation?
Finger dislocations can happen in different joints of the finger, namely the MCP, PIP, or DIP joints. A dislocation refers to the alignment of the bone – when a bone gets pushed out of its normal position in relation to the bone it’s directly connected to.
Dislocations in the MCP joint, where the hand meets the finger, are, unfortunately, quite common due to activities that excessively straighten the finger or put pressure on it. Protecting it is a tough job as it has only limited protection from the structures around it. Typically, it’s found more often in the index finger and the middle finger, especially if the finger is overstretched while also being pushed towards the little finger side. In most cases, the MCP joint dislocates backward. A clear sign of MCP joint dislocation is when the finger joints are bent in opposite directions, with an inability to straighten the finger implying a dislocated joint.
Dislocations in the PIP joints, or middle joints of the fingers, are the type most related to sports injuries – sometimes called “coach’s finger”. Signs might include a bent finger, pain, and a reduced ability to move the joint. The direction of dislocation could either be backward, forward or sideways; though a forward dislocation comes with more complications and difficulties in treatment. This kind of dislocation often happens by a ball hitting the fingertips.
The middle finger is most likely affected in backward dislocations, causing injuries to various parts of the finger like the ligaments and joint covering. Sometimes, a part of the joint might get trapped inside, causing dislocation of the joint and abnormal rotation of the finger making treatment more difficult. It’s worth noting that forward dislocation can sometimes be associated with injuries to the tendons, leading to further complications if left untreated.
Sideways dislocation can disrupt the ligaments causing the joint to become unstable and widen, seen in radiographs as the “Chinese finger trap”.
Lastly, dislocations at the last joint, or DIP joints, are usually noticeable with deformities at the fingertips. They can dislocate in all three directions: backward, forward, or sideways. Most commonly, these occur backwards and are often linked with fractures and skin injuries. Conversely, forward dislocations are likely associated with injuries to the tendons. It’s rare to find these dislocations without other related injuries, and they are usually handled with resetting the bone and stabilizing it with a splint.
Risk Factors and Frequency for Finger Dislocation
Between 2004 and 2008, around 166,000 finger dislocations were treated in US Emergency Departments. These dislocations mostly happened to people between fifteen and nineteen years old. They were also more common among African Americans than other racial groups. Mostly, basketball and football players experienced these dislocations.
Signs and Symptoms of Finger Dislocation
When examining a hand injury, medical professionals must consider various factors. A patient’s history is crucial to form a full understanding of the issue, including risk factors like Ehlers-Danlos syndrome, how the injury happened, whether the person is left or right-handed, any past finger injuries, their job, and their hobbies. The hand examination should be done in ample light to clearly see any skin damage, bruising, swelling, or deformities.
If the skin has cuts or scratches, the aim is to examine the area without blood if possible. Techniques such as using a finger tourniquet or an anesthetic with epinephrine can help achieve this. It’s crucial to check the finger’s full range of movement, both when the patient moves it and when the doctor moves it.
A thorough check of the nerves and blood vessels in the hand is paramount after an injury. The injured finger should be compared to the same finger on the other hand to check for sensitivity to light touch, sharpness, and distinguishing two separate points in close proximity, which can help identify any potential nerve damage.
Blood flow to the finger can be assessed by comparing the speed at which blood returns after pressing on the fingertip (capillary refill) with the same finger on the other hand. If a deformity is found, the examiner should also check for any twisting or bending.
There are specific tests to evaluate different parts of the finger. For instance, the Elson test checks the integrity of the central slip. This helps in assessing for rotation or angulation, a condition where the patient is asked to make a fist if possible, and all fingertips should point toward a part of the wrist called the scaphoid. Overlapping or “scissoring” of the fingers indicates a rotational problem. Checking for rotation or angulation can also happen by comparing the nails and fingertips to the same fingers on the unaffected hand. Palpation, or gently pressing on parts of the hand, can help to work out the most painful area.
Testing for Finger Dislocation
The recommended method for checking hand injuries is through standard X-rays. When taking these X-rays, it’s important to get clear views from multiple angles – side, front to back, and slanted – for each finger that’s been injured. It’s important to get a clear picture of the affected finger and ensure that it is not being hidden by any unaffected fingers.
One thing to keep in mind is that physical examinations often detect deformities due to rotation, rather than relying solely on the X-rays. Additionally, ultrasound technology, which is a topic of ongoing investigation, could potentially be used to recognize fractures and torn tendons.
Treatment Options for Finger Dislocation
If a person dislocates one of the joints in their hand, the treatment could involve surgery or it could be managed nonsurgically. This depends on factors like how easy the joint can be reset, how stable it is after being reset, or if it has affected certain important structures in the hand. Prior to any treatment, the affected finger is numbed using an injection of a local anesthetic like lidocaine, bupivacaine, or tetracaine.
For dislocations of the Metacarpophalangeal (MCP) joint, which is where the fingers meet the hand, nonsurgical treatment involves resetting the joint and then putting it in a splint. The medical professional can do this by straightening and pressing on the part of the finger closest to the hand and applying pressure to gently guide it back into place. If this doesn’t work after several attempts, it might indicate a more severe issue that requires surgical intervention. If the joint is reset successfully, the patient’s hand is placed in a certain position in a splint for about 3 to 6 weeks
Surgery is needed if the MCP joint can’t be reset manually. The surgeon might enter the hand from the back or the front, but the back is generally preferred to lower the risk of damaging nerves and blood vessels. Whether surgical or nonsurgical, the MCP joint is usually splinted in a slightly bent position for two weeks after treatment to prevent it from extending too far. Full recovery typically takes about 4 to 6 weeks.
For dislocations of the Proximal Interphalangeal (PIP) joint, which is the first joint within the finger, the treatment might change depending on the direction of the dislocation. PIP joints can be reset similarly to MCP joints, and then put in a splint. If the attempted reset is successful and the joint moves well without slipping, then it’s typically stable. Anyone with a joint that’s unstable after a reset likely needs surgery.
If a Distal Interphalangeal (DIP) joint is dislocated, which is the joint closest to the fingertip, the treatment is less complicated than a PIP dislocation. Similarly to the other joints, a DIP joint can be reset and then put in a splint. If it can’t be reset, surgical intervention is required. Immediate motion exercises are usually encouraged after surgical reduction.
What else can Finger Dislocation be?
Several injuries can occur in our hands, like:
- Fracture-dislocation: This is when a bone breaks and moves out of place.
- Collateral ligament injuries, often called finger “sprains”: The collateral ligaments are tissues that connect the bones of each finger joint, and these can be damaged or stretched.
- Tendon avulsion: This happens when a tendon, a fibrous cord attaching a muscle to a bone, gets torn away from the bone.
What to expect with Finger Dislocation
Dislocations of the MCP joint often require surgery, and the recovery time to regain typical motion usually takes roughly 4 to 6 weeks. Many PIP joint dislocations, except those to the side, are typically stable after being realigned. However, similar to the MCP joints, side dislocations of the PIP and DIP joints often require surgical treatment. It’s worth noting that isolated DIP joint dislocations are uncommon.
Possible Complications When Diagnosed with Finger Dislocation
After treating a DIP dislocation, chronic stiffness is a common experience. Overdoing treatments such as wearing a splint for too long or trying many times to reduce a volar PIP joint dislocation increases the chances of volar plate scarring and flexion contractures (permanent bending of the joint). Chronic pain and limited mobility of the MCP, PIP, and DIP joints are also common effects.
Not catching a volar plate injury on time (or missing it completely) may lead to complications such as boutonniere deformity (muscle becomes weak or deformed), swan neck deformity (joint positions change), laxity (loose joint), and contractures (hardening of the joints and muscles). If finger dislocations are missed over a long time, swan neck deformity, PIP flexion contracture, and mallet finger deformity (drooping of the end of the finger) are also possible.
Common Issues:
- Chronic stiffness
- Volar plate scarring and flexion contractures
- Chronic pain
- Limited mobility of MCP, PIP, and DIP joints
- Boutonniere deformity, swan neck deformity, laxity, and contractures due to missed volar plate injuries
- Swan neck deformity, PIP flexion contracture, and mallet finger deformity due to chronic unrecognized finger dislocations
Recovery from Finger Dislocation
When treating simple dislocations, it’s usually possible to allow some movement soon after the treatment. However, the motion past neutral is limited with a specialized splint known as a dorsal extension block splint. For complicated dislocations, it’s customary to immobilize the joint (called MCP joint) in a slightly bent (30 degrees flexion) position for two weeks using a removable dorsal extension block splint. During this period, gentle movements and exercises to improve the range of motion are prompted.
After getting rid of the splint, patients are encouraged to start a variety of hand exercises. These activities include making a fist, lifting fingers, stretching passively, and exercises that cover the full range of motion and strengthening the internal and external hand muscles. One crucial aspect is to ensure that the joint located at the furthest point of the fingers (the distal interphalangeal joint) is activated as soon as possible. Doing so promotes smooth gliding of the lateral bands which benefits overall hand movement and functionality.
Preventing Finger Dislocation
There’s often a need for physical therapy, occupational therapy, and training before returning to sports or work after an injury. It’s important for the orthopedic or hand surgeon to guide and educate the patient on how to look after the injury until they’re fully healed.
