What is Tarsal Navicular Fractures?
Fractures of the tarsal navicular bone, situated in the foot, usually occur due to physical trauma or excessive stress. These fractures are more common in young people and athletes. Even though breaking a bone in the mid-foot is quite rare, up to a third of all stress fractures occur in the tarsal navicular bone. Nonhealing and bone death can occur due to the bone’s limited blood supply and the complexity of the joint. Typically, these fractures need surgery to heal, although in some situations, non-surgical treatments can be sufficient.
The navicular bone is shaped like a wedge and interacts with several other bones in the foot. It has a unique orientation and is connected to many joints, which means a large part of it is covered in joint cartilage, a smooth tissue that allows for easy movement of the joints.
The blood supply to the navicular bone’s top surface comes from certain branches of arteries in the foot. Meanwhile, another artery branch supplies blood to the inner sole of the navicular. Some studies suggest that there’s a zone without a direct blood supply in the navicular, which may lead to bone death when these fractures occur.
The tarsal navicular is a key part of a larger joint in the foot, the Chopart joint, which includes two sub-joints. Both of these sub-joints play a vital role in side-to-side movement of the foot.
What Causes Tarsal Navicular Fractures?
Stress fractures of the tarsal navicular, a bone in the foot, are still not fully understood, but they’re generally considered to be a type of injury that happens over time due to repeated minor damages to the bone. On the other hand, traumatic injuries to this bone are better understood and can lead to different types of fractures, including avulsion fractures, tuberosity fractures, and body fractures.
Avulsion fractures of the navicular bone can happen in different ways, depending on where the impact to the midfoot hits. If the top of the foot is overly flexed, it can put too much stress on the deltoid and dorsal capsules, causing a fracture. Overpulling from a tendon in the back of your leg can result in medial and tuberosity fractures, and fractures on the bottom part of the bone are typically caused by ligament injuries.
Body fractures of the navicular bone can be caused by either a direct impact or an indirect force. The Sangeorzen classification, a system made in 1989, is commonly used to grade these fractures. It looks at things like the direction of the fracture line, how much nearby joints are disrupted, and where the foot is displaced. According to this system, a Type-1 injury happens in the coronal plane (a vertical cut creating a front and back half) without any angulation of the forefoot. A Type-2 injury has a certain type of fracture line with the major fragment and forefoot displaced away from the midline. A Type-3 injury is a shattered fracture in the sagittal plane (a vertical cut creating a left and right half) with the forefoot displaced to the side. All these fractures are thought to be caused by forces on a foot that is overly flexed.
Risk Factors and Frequency for Tarsal Navicular Fractures
Midfoot fractures are only a small part of all foot injuries, but about one-third of them are stress fractures. These types of injuries occur most frequently in the navicular bone, usually due to car accidents. They can also happen because of falls or blunt force impacts. Young people, particularly competitive athletes who put a lot of strain on their feet, are at a higher risk for stress fractures.
- Midfoot fractures make up a small percentage of all foot injuries.
- About one-third of all foot stress fractures happen in the midfoot.
- Traumatic navicular injuries often occur from car accidents, followed by falls and blunt impacts.
- Stress fractures are especially common in young, high active individuals like competitive athletes.
Signs and Symptoms of Tarsal Navicular Fractures
Avulsion fractures, which are a type of fracture that occurs when a small piece of bone attached to a tendon or ligament gets pulled away from the main part of the bone, can cause intense pain in the middle of the foot, especially when pushing off with the broken part. Those who have a navicular body fracture, a specific type of bone fracture located in the foot, generally can’t put any weight on the injured foot and have a lot of swelling on the top and inside of their foot. This is due to the way the injury happened and because of the disturbances in the inner structure of the foot.
It’s important for doctors to perform a comprehensive check of the patient’s blood flow and nerves because of the possibility of complications like compartment syndrome, a dangerous condition where pressure builds up in the muscles that could lead to nerve or muscle damage. They should also examine the patient for any open wounds. Note that people often have other injuries in the same foot when they have a navicular body injury; in one recent study, out of 24 patients with this type of injury, 15 had additional injuries.
On the other hand, people with navicular stress fractures usually have a less severe presentation. They might have a longer history of vague discomfort in the middle of the foot. When these patients are examined, the pain usually centers on the top part of the middle of the navicular bone, which is located on the inner side of the foot.
Testing for Tarsal Navicular Fractures
If your doctor suspects that you have fractured a bone in your foot called the tarsal navicular, they will likely start by taking three different x-ray scans of your foot. These X-rays will be taken from the top, side, and at an angle. Normally, these X-rays are taken without you putting weight on your foot. However, if they suspect you might have damaged your ligaments or have a minor injury, they might ask you to stand and put weight on your foot for the x-ray.
Another type of x-ray, called an external oblique radiograph, can be useful for looking at a specific kind of fracture called a tuberosity fracture. A tuberosity fracture is when a particular part of the bone has been broken. When looking at these x-rays, your doctor will also be careful to check for an accessory navicular. This is an extra part of the bone that some people have, and it can be spotted by comparing an x-ray of your injured foot with an x-ray of your uninjured foot.
Sometime, in case of more forceful injuries, a technique called computed tomography (or CT for short) might be used. This imaging method gives a more detailed image of complex fractures, the shape of the joint between two specific bones in your foot, and helps prepare for surgery if needed. The CT scan can even create a three-dimensional picture of your foot bone.
Treatment Options for Tarsal Navicular Fractures
Tarsal navicular fractures, or breaks in one of the bones in the foot, can be treated in various ways. Their specific characteristics, such as the size of the fracture, how much the broken bone has moved, the exact location of the fracture, how splintered the bone is, as well as the condition and strength of the foot’s soft tissues play a deciding role. Besides, if the patient also has other injuries or health conditions, and their overall functional status become crucial determining factors too.
For navicular stress fractures, doctors typically immobilize the foot and limit weight-bearing activities for about six to eight weeks. However, if the patient has high physical activity requirements, like athletes, they might choose surgery. If surgical intervention is chosen, doctors most likely would use a method called ‘open reduction and internal fixation’ to repair the fracture.
Likewise, traumatic navicular fractures could be addressed either surgically or nonsurgically. Minor fractures that don’t cause the bone pieces to move can be usually managed non-surgically, with a short leg cast for weight-bearing and eventually a walking boot.
If the broken pieces of bone have moved significantly, surgery would typically be necessary. In this case, the same ‘open reduction and internal fixation’ procedure is used. The main goals of surgery are to restore the fracture to its original position, to rebuild the length of the inner bone column, and to establish a firm bone structure that will allow for early movement.
What else can Tarsal Navicular Fractures be?
If doctors suspect a navicular bone fracture (a bone in the foot), they may also consider other conditions with similar symptoms. These could include:
- A condition affecting the tendon attached to the same bone (posterior tibialis tendinopathy)
- A tear in a ligament in the foot (the spring ligament)
- a common but harmless condition where there’s an extra (accessory) navicular bone
To tell the difference between these conditions and a broken navicular bone, doctors can use an MRI scan. However, they often don’t need to use this at first, as X-rays and CT scans can usually identify a broken navicular bone quite easily.
What to expect with Tarsal Navicular Fractures
People who have experienced a navicular stress fracture generally have a positive outlook if they receive prompt and appropriate treatment. This is supported by a recent study where 57 out of 62 patients were able to resume their normal activities at the same level as before their injury, which indicates an excellent clinical outcome. Furthermore, in a case study of 10 patients with more complex tarsal navicular fractures, all patients who underwent surgery had successful bone healing without needing joint fusion surgery, as observed after an average of 20 months.
Possible Complications When Diagnosed with Tarsal Navicular Fractures
Like most areas around a joint, there are several potential complications and risks associated with a navicular (one of the bones in the foot) fracture. These complications can include bone death (osteonecrosis), improper bone healing (malunion), failure of the bone to heal (nonunion), persistent stiffness, and pain.
Patients with non-healing fractures may have a deformed foot, but this can be managed with the use of special footwear or potentially surgery, depending on how severe the deformity is. Osteonecrosis, on the other hand, can result in a significant deformity. The main treatment goal in these cases is to restore the foot’s length and alignment, usually by fusing certain foot bones together.
Common complications and risks of navicular fractures:
- Bone death (osteonecrosis)
- Improper bone healing (malunion)
- Failure of the bone to heal (nonunion)
- Persistent stiffness
- Pain
- Foot deformity
Preventing Tarsal Navicular Fractures
Navicular stress fractures, which are often seen in competitive athletes, are typically caused by excessive and continuous use of the foot. Given the high number of cases amongst athletes, it’s crucial for them to understand the importance of correct training techniques and using the right equipment when participating in their sports. These measures can help lessen the pressure exerted on the foot, thereby reducing the chances of this type of fracture. Furthermore, fractures that are quickly immobilized and treated generally have better healing outcomes. That’s why it’s critical to have these injuries assessed promptly. This can’t be stressed enough.
