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Accessory Navicular
Fitness Health Physical Health

Do you know what Accessory Navicular is?

 Many people are unaware that they have this condition, as in most cases it does not cause symptoms. However, some individuals develop a pain syndrome characterized by swelling and pain in the area when the bone or tendon suffers damage due to trauma, irritation from poorly fitting shoes, or overuse.

In many cases, individuals with accessory navicular syndrome may also have flat feet. “It is most often asymptomatic and found incidentally on radiographs, although it can cause local pain and swelling. The pain is usually aggravated by physical activity or local trauma.”

Most carriers are asymptomatic

The prevalence of accessory navicular in the population is estimated to be around 10% to 12%. However, symptoms only occur in a small proportion, which may be up to 0.1% (1 in 1000) of carriers.

Types of Accessory Navicular

This accessory bone  is commonly classified into three types.

Clinical Picture

Symptoms of this condition usually first appear in adolescence, when the ossification process is taking place, which will transform the cartilaginous nucleus of the accessory navicular into bone.

The most common symptoms are the presence of a visible bony prominence on the inside of the foot, redness, pain and swelling in this region. Pain may occur when palpating the area, or when it rubs against footwear, as well as during or after a period of activity, indicating local instability.

  • Local pain
  • Volume increase
  • Redness
  • Worsening of symptoms during physical activity

How to diagnose Accessory Navicular?

Diagnosis is usually made through clinical evaluation, which includes foot shape, palpation, gait assessment and patient mobility. X-rays can aid in diagnosis, both by demonstrating the presence of accessory bone, when already ossified, as in figure 2, and by analyzing the relationships between the bones of the foot on weight-bearing radiographs.

Magnetic resonance imaging (Figure 3) provides a more detailed view of the tendons and cartilage, as well as the presence of edema between the navicular and the accessory bone, which can demonstrate the location of instability and the probable origin of pain. It also provides characteristics related to the posterior tibial tendon, which is inserted into this bone and may be related to the painful genesis of the symptoms, and its analysis is fundamental for therapeutic decision-making.

Figure 2: Anteroposterior X-ray of the foot, with red arrow showing the accessory navicular bone

 

Figure 3: Axial resonance image demonstrating edema in the accessory navicular and mild insertional tendinopathy of the posterior tibial tendon.

Conservative Treatment of Accessory Navicular

In general, non-surgical treatment can resolve the symptoms of this syndrome. Immobilization with a removable boot to rest the affected area and relieve inflammation, shoe adjustments, use of ice and oral non-steroidal anti-inflammatory drugs to reduce pain and inflammation help relieve symptoms.

Changing impact activities and identifying the causal factor are part of this stage of treatment. Physiotherapy with exercises to strengthen the surrounding muscles can reduce pressure in the area, stabilizing the structures that are associated with the painful process.

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Symptoms:

Symptoms of this condition usually first appear in adolescence, when the ossification process is taking place, which will transform the cartilaginous nucleus of the accessory navicular into bone. The most common symptoms are the presence of a visible bony prominence on the inside of the foot, redness, pain and swelling in this region. Pain may occur on local palpation, or when the area is rubbing against footwear, as well as during or after a period of activity, indicating local instability.

Diagnosis:

The diagnosis is made with the help of imaging tests, such as x-rays, and it is important

to avoid incorrect assessment it is confused with a fracture. It is worth remembering that ossification only occurs at approximately 4 years of age (a little earlier in girls and a little later in boys).
In some cases, additional tests to assess for signs of overload, dysfunction or inflammation at the site, such as ultrasound or MRI may be necessary.
 Furthermore, clinical examination is essential, and should assess whether the patient presents any changes.
compatible with the problem.

Treatment:

Treatment, when necessary, normally begins with conservative measures such asimmobilizations, use of insoles and physiotherapy to control pain and improve

foot function.

Eventually, when there is no improvement with this treatment, surgical treatment maybe performed, which generally consists of resection (removal) of the accessory navicular and
reinsertion of a portion of the posterior tibial tendon, which may be accompanied by correctionof foot deformity, if any.

 Many people have pain and/or a lump in the medial (inner) region of the foot. This situation may be due to the presence of an accessory navicular.

The accessory navicular is an accessory ossicle present next to the navicular bone and which receives the insertion of the posterior tibial tendon.

In most patients, this change does not cause symptoms, however, in some people, the presence of this bone can lead to pain, local volume and predispose to diseases such as flat feet .

Epidemiology

Accessory navicular is present in approximately 10% of the population, being more common in female patients, being bilateral in up to 70% of cases.

Clinical presentation

“It is most often asymptomatic and found incidentally on radiographs, although it can cause local pain and swelling. The pain is usually aggravated by physical activity or local trauma.”.

Foot with Accessory Navicular

Classification of the Accessory Navicular

There are 3 types of accessory navicular:

  • Type 1: small ossicle, usually “inside” the tendon. They are usually asymptomatic.
  • Type 2: larger bone, connected to the navicular by cartilage. These are the most common and most frequently symptomatic.
  • Type 3: bone fused to the navicular, forming a medial volume that often, due to friction, leads to pain.

In which tests do we see this change?

Accessory Navicular

The navicular is a bone that articulates with the head of the talus and the three cuneiforms. It is shaped like a “C,” a horseshoe, or a ship’s hull, and is located in the highest portion of the plantar arch, the medial curvature of the sole of the foot. This bone is important for midfoot movements, especially for pronation and supination (outward and inward movement with rotation).

. The accessory navicular is a congenital alteration in the formation of the tuberosity of the navicular bone due to the division of its ossification matrix during the embryonic phase. This leads to the appearance of an accessory bone (sesamoid) on the medial protuberance of the navicular.

The accessory navicular is classified into three types:

Type 1 – Small accessory bone without direct connection or articulation with the body of the navicular. Usually rounded and well-defined, located in the plantar portion of the insertion of the posterior tibial tendon. Asymptomatic in most cases.

Type 2 – Bony portion clearly related to the body of the navicular, separated by a fibrocartilaginous plate (synchondrosis). Frequently causes painful symptoms, especially after physical activity.

Type 2 navicular can be located medially, at the tip of the tuberosity and subject to tensile force by the posterior tibial tendon (Type 2A), or more plantarly, below the navicular and subject to shear force by the same tendon (Type 2B).

Type 3 – Bony extension of the navicular tuberosity. The accessory bone is joined by a rigid and continuous bony bridge, giving a more elongated shape to the navicular.

The presence of an accessory navicular can cause pain and discomfort when there is some form of injury involved, such as local compression, trauma or repeated traction by the posterior tibial tendon. Inadequate footwear, impact activities and sprains are the main factors that can cause the onset of pain. Symptoms often occur in early adolescence with increased weight and sports activity.

The fall of the plantar arch, flat foot or pes planus, is related to the presence of the accessory navicular due to the increase in bone length and the change in the insertion of the posterior tibial tendon. This modifies the line of pull of this tendon, which begins to act more as an adductor than a supinator of the forefoot, thus decreasing the support of the plantar arch.

Initial treatment aims to alleviate pain and local inflammation.

Using an immobilizing boot, ice, and anti-inflammatory medication can relieve acute symptoms. Changing footwear to sneakers with an insole to support the plantar arch improves comfort and provides support, reducing the mechanical overload of the tendon related to the accessory navicular. Physiotherapy can enhance tendon strength and provide symptomatic relief.

Surgical treatment is indicated in recurrent cases or when there is no improvement with conservative treatment. Surgery involves removing (excising) the accessory navicular, and it may be necessary to reinsert (replace) or retension (shorten) the posterior tibial tendon in the navicular.

Surgical Treatment of the Accessory Navicular

When symptoms of accessory navicular syndrome do not go away or reappear after previous treatment, surgical approaches may be recommended. The procedure usually involves removing the accessory bone, reshaping the area, and repairing the posterior tibial tendon to improve its function.

 Conclusion:

the accessory navicular is a prevalent anatomical variation that often goes unnoticed, as it is frequently asymptomatic. However, for some individuals, it can lead to pain and discomfort, particularly with physical activity. Understanding this condition is essential for effective diagnosis and management. With appropriate treatment, including rest, physical therapy, or, in some cases, surgical intervention, those affected can find relief and improve their quality of life. Awareness of the accessory navicular can help both patients and healthcare providers address any issues that may arise, ensuring better foot health overall.

FAQs

1. Why does the accessory navicular hurt?

The main causes of pain related to the accessory navicular are instability in its union with the navicular bone, especially in type II, the tendinopathy it causes at the insertion of the posterior tibial tendon and its friction with footwear, especially very bulky ones.

2. How to treat accessory navicular?

Most people with this accessory bone will be asymptomatic. For those who do have symptoms, periods of rest, removable orthopedic boots, short courses of anti-inflammatories and shoe adjustments will usually be sufficient to control symptoms. For individuals who are resistant to these measures, surgical treatment may be an option.

3. Do I need to remove my accessory navicular?

The answer is no. Only a minority of individuals who have symptoms and are refractory to conservative treatment need to remove this bone. Therefore, in general, this bone does not need to be removed.

 

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