What is Fifth-Toe Deformities?
The forefoot is the front part of your foot which stretches from the joint where the long bones of your foot (metatarsals) meet the small bones (tarsals) up to the tips of the toes. If you look into issues or abnormalities with the toes, you’ll often find these divided into two categories: those involving the big toe (also called the hallux) and those involving the smaller toes. The small toe on the side of your foot, or fifth toe, is the furthest and most on the side of the forefoot. It’s made up of three small bones, known as the proximal, middle, and distal phalanges, which are connected by two joints.
The surface layer of the foot, or layer 1, consists of various muscles including the abductor hallucis muscle that moves the big toe away from the other toes, and the abductor digiti minimi muscle that performs a similar function for the fifth toe. There’s also a muscle named the flexor digitorum brevis that bends the joints of toes 2 to 5.
Just beneath this surface layer is layer 2. It contains long tendons that go to toes 2 to 5, helping them to bend. One of these tendons, the flexor hallucis longus tendon, goes to the big toe to bend it. Additionally, this layer holds the quadratus plantae muscle, which aids in bending toes 2 to 5, and the lumbrical muscles, which helps to flex and extend the joints of toes 2 to 5.
Next, in layer 3, you find a muscle named the flexor hallucis brevis that bends the big toe. This muscle contains the small bones of the big toe. Also, within this layer are the adductor hallucis muscle which moves the big toe towards the other toes, and the flexor digiti minimi brevis muscle that flexes the fifth toe at the joint with the metatarsal.
The deepest layer, layer 4, houses muscles that move your toes away and towards each other at the metatarsophalangeal joints, or the joints between the metatarsals and the phalanges. This layer also houses the peroneus longus tendon, which contributes to the turning and flexing of the ankle, and the tibialis posterior tendon, which twists the foot and helps maintain its arch.
Finally, on the top of the foot are muscles like the extensor digitorum longus, which helps extend toes 2 to 5 and contribute to the upward bending of the ankle, and the extensor hallucis longus, which extends the joint of the big toe. Having a clear understanding of foot anatomy helps to comprehend various foot deformities. For example, the fifth toe can sometimes have abnormalities from birth, like overlapping, curling, or developing a small bump on its outside edge (a bunionette).
What Causes Fifth-Toe Deformities?
Overlapping Fifth Toe, often known as crossover toe or digiti quinti varus, is a birth defect. It happens because of the tightening of the tissue on top of the skin, around the joint of the big toe, or the extensor tendon complex of the fifth toe. This condition leads to the toe bending backwards, moving towards the other toes, and rotating outwards. The main tendon on the inside of the toe, called the extensor digitorum longus tendon, can shift over time. This shift can make the contraction worse and exaggerate the deformity.
Curly Toe, also known as underlapping toe or underriding toe, is also a congenital deformity. It primarily involves the fifth or sometimes fourth toe. It is characterized by the bending of the toe, its inward and external rotational deformity. There is debate about what causes a curly toe. One theory suggests it can be due to the extreme turning of the foot inwards during the late stage of walking, causing the flexor digitorum longus to shift out of place, which changes the mechanical axis of the flexor tendons. This then results in the toe bending and turning inward. Another theory suggests that a curly toe is caused by excessive pulling of the flexor digitorum longus tendon and eventual shortening of the tendon, leading to a bending deformity.
Bunionette Deformity, also known as tailor’s bunion, is another toe condition that includes a bony lump along the side of the fifth metatarsal head, basically the joint at the base of the little toe. Factors like a large metatarsal head, bending of the metatarsal towards the outside, increase in the angle between the fourth and fifth metatarsal bones (IMA), and the development of hard skin (keratosis) are known contributors to painful bunions.
Risk Factors and Frequency for Fifth-Toe Deformities
Overlapping fifth toes and curly toes present from birth aren’t more common in any particular gender and tend to affect both feet. For instance, roughly 13.8% of people have a small bunion, and about 61.2% have someone else in their family with the same condition.
Signs and Symptoms of Fifth-Toe Deformities
Deformities of the fifth toe are often detected in young children whose parents might be worried about how the toe looks or the children’s trouble finding comfortable shoes. Here, we will look at three common types of these deformities:
- Overlapping Fifth Toe: This issue is seen at the joint connecting the foot and the fifth toe. The toe turns inwards, upwards, and twists, causing it to overlap the fourth toe. You may see tightened skin or feel a rigid tendon on top of the fifth toe. Sometimes, the other joints in the toe become affected, making the toe divert more. This issue can usually be corrected without surgery, and when under pressure from standing or walking, the toe may look more normal.
- Curly Toe Deformity: This condition creates a toe that curls under the nearby toe, heading towards the center of the foot, due to the toe’s joints bending inwards. Usually, this issue is temporarily correctable, but it can become a rigid deformity if the skin and soft tissue underneath the foot tighten. Hard, thickened areas of skin may arise at the tip or other parts of the toe due to the increased contact pressure with the shoe.
- Bunionette Deformity: This deformity usually shows up as painful hard skin over the head of the fifth toe bone, making the front part of the foot wider. This condition usually happens with flat feet and bent big toe deformities.
Testing for Fifth-Toe Deformities
If you have a birth defect that affects your fifth toe, you usually don’t need any routine lab tests or X-ray scans. Even though an X-ray might show the deformity, the most crucial assessment tool is a physical check-up by your doctor. For a specific condition called Bunionette Deformity, an X-ray taken while you stand can show an increased angle between the bones in your foot (more than 12 degrees between the metatarsal bones and more than 14 degrees between the metatarsal bone and the bones of the toe).
Treatment Options for Fifth-Toe Deformities
If a child has an overlapping fifth toe, it is often seen to correct itself as the child starts to walk. Sometimes bandages or braces might be used to help straighten the toe, but the condition often returns once this is stopped. In such cases, specially made shoes may help provide relief to the overlapping fifth toe that doesn’t correct itself.
However, if the overlapping fifth toe is causing repeated irritation or makes it hard to wear shoes, surgical treatments become necessary. The goal of this surgery is to correct the position of the toe. Sometimes, the fourth toe is used to keep the fifth toe in its correct place. A commonly used surgical procedure for the overlapping fifth toe is the Butler procedure, which involves making an incision over the joint of the toe, removing part of the tendon and joint capsule, which allows the toe to rest in the correct position.
Congenital curly toe, a condition where the toe curls under instead of pointing straight, often corrects itself when a child starts walking. If it does not, and it causes discomfort, shoe modifications can be helpful. If the condition persists and causes discomfort, surgical intervention may be required. Here, they’ll make a small cut in one of the tendons of the toe or remove part of the bone from the toe to straighten it.
Bunionette deformity, also known as a tailor’s bunion, is a bony bump that forms on the joint at the base of the little toe. In its initial stages, you can try to manage it by wearing wide shoes, using special supports, taking anti-inflammatory drugs, and using forefoot barrier pads. However, if these methods don’t work, surgery may be needed. During the surgery, the doctors will either remove part of the bone causing the bump or realign the bones of the foot to correct the deformity.
What else can Fifth-Toe Deformities be?
Deformities in the smaller toes are generally caused by an imbalance in the foot’s internal and external muscles. There are a few common toe deformities, that include:
- Mallet toes: Mallet toes are bending deformities at the last joint of the toe. This most often happens due to a tight or contracted ‘flexor digitorum longus’ muscle which connects to the base of the end part of the lesser toes.
- Hammer toes: These are bending deformities at the first joint of the toe and straightening of the end joint. This is usually caused by an overpull of the ‘extensor digitorum longus’ muscle.
- Claw toes: These are characterized by a straightening deformity at the joint where the toe meets the foot, which results in uncontrolled bending of the first and last joints of the toe. This kind of deformity is more commonly seen with nerve and muscle diseases and inflammatory joint conditions.
These deformities can be flexible, meaning they can be controlled by your muscles, or rigid, meaning they cannot be control by the muscles and are permanently in the deformed state.
What to expect with Fifth-Toe Deformities
Most birth defects of the fifth toe (pinkie toe) usually correct themselves once the child starts to walk. However, if they don’t, they can most likely be managed with simple non-surgical methods, such as strapping the toe or changing the type of shoes worn.
In very rare instances where surgery is required, a procedure called ‘Butler procedure’ and ‘flexor tenotomies’ are typically used. They are effective in fixing overlapping toes and “curly toes,” respectively.
In addition, minimally invasive techniques, which involve making small cuts instead of large incisions have shown promising results following correction of a bunionette (a small bunion, or swelling on the pinkie toe joint).
Possible Complications When Diagnosed with Fifth-Toe Deformities
The main issue people with persistent congenital fifth toe deformities usually face is discomfort when wearing shoes. If this condition doesn’t clear up early in childhood, non-surgical treatment methods can still often work, although the possibility of the deformity returning in the future increases. Surgery can be an option with minimal complications, but the most common issues post-surgery are infections and scarring.
Common issues related to persistent congenital fifth toe deformities could include:
- Discomfort when wearing shoes
- Return of the deformity over time
- Post-surgery infection
- Scarring after surgery
After corrective surgery for a toe deformity (bunionette correction), some complications could happen, such as:
- Delayed wound healing
- Malunion – poor alignment of the bone
- Nonunion – the broken bone fails to heal
- Metatarsalgia – pain in the ball of the foot
- Recurrence of the bunionette
- Overcorrection or under-correction of the deformity
- Subluxation (partial dislocation) of the toe joint
Recovery from Fifth-Toe Deformities
Using K-wire fixation, a procedure to hold bones together, has been shown to be more effective than the repeated use of straps. Stitches are often removed about 2 to 3 weeks after imaging scans are taken, while K-wires are usually taken out in a doctor’s office 6 weeks later. During the next 6 weeks, it’s suggested to keep the K-wire area strapped for protection, a method known as bonnet tapping.
If you have a procedure on your metatarsals, or the long bones in your foot, you’ll have a foot splint for 2 weeks, followed by a short leg cast for an additional 4 weeks. After 6 weeks, doctors will usually allow you to put weight on your feet. However, they advise waiting 8 to 10 weeks before returning to regular activities, during which supportive shoes should be worn. After that, by around 12 weeks, most patients are usually able to tolerate activities involving contact.
Preventing Fifth-Toe Deformities
If a child has a birth defect affecting their fifth toe, it’s important for parents to understand that these defects usually do not cause any symptoms and often get better as the child starts to walk. If the child is experiencing discomfort when wearing shoes, there are many non-surgical ways to manage this issue. So, in most cases, there’s no need to worry excessively or immediately consider surgery.
