Exostosis: development and accompanying symptoms of bone proliferation

Exostosis - is the pathological formation of new bone growths on an already existing bone surface. The cause can be chronic overloading, such as occurs with a hallux valgus (bunion). Very often, however, an exostosis is also the result of arthrosis (degenerative wear and tear of the joints). In this article, you will learn everything about the most important issues surrounding the topic of exostosis of the foot:

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The terms exostosis and ganglion are often used synonymously, which is not correct from a medical point of view. Strictly speaking, they are two different clinical pictures.

The term exostosis (from the Latin ex 'out', os 'bone' and ose ‘disease’) or ectopic bone formation - refers to pathological bone protrusions or bony outgrowths. These often form in the course of arthrosis. The arthrosis in the joint leads to outgrowths at the joint edges, which are called exostoses.

A ganglion is a non-specific term for a lump or nodule. In orthopedics, it is usually an outpouching of a joint or tendon sheath filled with gelatinous fluid. In this case, excess fluid forms at joints or tendon sheaths, which becomes noticeable externally as a bulging elastic thickening or swelling.
Most often, an exostosis or a ganglion occurs around the hand. However, both clinical pictures can also occur on the knee or foot.

An exostosis can basically occur anywhere where bones are present. Either these areas are "displaced" bones that form an exostosis or there is joint damage that leads to exostosis formation in the context of osteoarthritis. The following locations on the extremities are most affected:

An exostosis occurs preferentially in the hand or wrist area

• On the back of the hand, an exostosis develops mainly on the outside of the hand.
• On the fingers or thumbs, exostosis form most often near the joints.
• Osseous prominence on the wrist can occur both internally and externally.

The foot is also predestined for the formation of exostoses:

• Plantar Hyper phalangeal Bone:
  An exostosis often occurs as a bony prominence on the dorsum of the foot. This is also a new formation of bone substance that can cause pain due to pressure and friction on the shoe.
• Exostosis of the metatarsus:
  Exostoses also commonly occur on the metatarsal bone as visible, small bony prominences. Here, ectopic bone formation usually develops in connection with hallux rigidus, a change in the toe joint caused by osteoarthritis. Another cause can be chronic overloading.
• Hyperextension of the calcaneus (Haglund's heel):
  Haglund exostosis is a bony protrusion of the calcaneal tuberosity. This so-called Haglund's heel can affect one or both feet. The supra-leg protrudes prominently at the back of the heel and can thus lead to chronic pain due to pressure points in the shoe.

The symptoms caused by an exostosis depend greatly on the extent and location of the exostosis as well as its cause.

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What does an exostosis look like?

An exostosis is a bumpy or spur-like bone protrusion or a new bone formation that can form in the context of osteoarthritis or joint damage. This outgrowth is often recognizable and palpable as a bump or bulge and does not always have to lead to pain or mechanical problems.

Overleg-associated pain

An exostosis can significantly disrupt the movement of the joints. This creates a kind of vicious circle: when the joint is damaged, the cartilage gradually loses its gliding and buffering function. As a protective function, new bones (exostoses) form at these points, but they are misaligned. This ectopic bone formation further restricts the mobility of the joint. This usually causes pain.

Additional pain is caused by footwear rubbing additionally against a protruding exostosis. Redness, irritation, and pressure points around the shoe occur. If an exostosis is present on the foot, wearing shoes can become very painful. In these cases, surgical removal of the osseous prominence is recommended.

Exostosis and ganglion can be confused by the layperson because of their outward similarity. A ganglion (not a real exostosis) is a fluid-filled outgrowth that develops on a joint capsule or tendon sheath. The real exostosis or osteophyte, in contrast to the fluid-filled ganglion, is a bony outgrowth. Therefore, if unusual thickening or swelling occurs around the foot, a foot specialist should always be consulted for clarification.

Based on his many years of expertise as a foot surgeon, Dr. Tonio Gottlieb, MD in Berlin can make an accurate diagnosis and recommend optimal treatment options for you. In addition to a detailed medical history, he will assess the appearance and mobility of the foot during a manual examination. In most cases, the diagnosis can already be verified by palpation. An additional X-ray examination is often performed to confirm the diagnosis.

For patients with complaints due to an exostosis, the foot surgeon Dr. Tonio Gottlieb, MD in Berlin is exactly the right specialist. As a foot specialist with over 20 years of experience, he offers you a precise diagnosis and attaches great importance to a cause-oriented treatment. Make your personal consultation appointment right away - even if it's for a second opinion.

However, to achieve permanent freedom from symptoms beyond this symptomatic treatment, the cause should also be investigated and, if possible, also surgically remedied. When diagnosing an exostosis, Dr. Tonio Gottlieb, MD, will therefore always suggest a cause-oriented treatment method.

Dr. Tonio Gottlieb, MD, the specialist foot surgeon in Berlin advises:

"Depending on the location and size of an exophyte in the foot, ablation of an exostosis can often be performed as an outpatient procedure under local anesthesia. It is a minor surgical procedure. In addition to treating the exostosis, I believe it is important to always diagnose and treat the underlying condition. By ablating the ectopic bone formation alone, I would only be treating the symptom and not the cause."

Case studies with different causes.

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Dr. Tonio Gottlieb, MD in Berlin, the specialized foot surgeon advises:

"Patients often come to me with an exostosis that is causing pain. Through a comprehensive history and examination on the foot platform, I can usually quickly determine the cause of the exostosis. It's important for the treatment plan going forward that the underlying condition is also diagnosed and treated."

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Results can also be achieved with conservative methods

If an exostosis of the foot causes only minor discomfort, conservative treatment methods can bring relief. Here, attention should be paid above all to the adjustment of the footwear to avoid pressure points and friction at the site of the bone growth.

Tip: Give your feet a regular break from shoes and walk barefoot as often as possible when you are pain-free.

• Hallux rigidus or arthrosis of the metatarsophalangeal joint of the big toe
• tarsal or metatarsal arthrosis
• hallux valgus
• Hammer or claw toes
• chronic overuse

Exostosis due to hallux rigidus or arthrosis of the metatarsophalangeal joint of the big toe

Exostoses that manifest on the first metatarsal usually occur due to underlying hallux rigidus.
Hallux rigidus is a pathological change in the area of the metatarsophalangeal joint of the big toe. In the context of this disease, there is a degenerative change in the joint due to arthrosis (metatarsophalangeal joint arthrosis). During this process of wear and tear, bony exostoses very often form.

Exostosis due to tarsal or metatarsal arthrosis

Tarsal arthrosis is cartilage wear directly at the tarsal. In metatarsal arthrosis, this occurs between the metatarsus and the tarsus. Constant overloading causes the cartilage wear to progress successively. The buffering cartilage layer recedes further and further until the bones finally rub directly against each other. Sometimes bony attachments can also form, which then appear as an exostosis.

Exostosis due to a hallux valgus (bunion)

A hallux valgus deformity is the pathological inward rotation of the big toe. The first symptoms occur on the protruding inner side of the first metatarsal bone, the bunion. Here, at the widest point of the foot, mechanical irritation leads to painful inflammation of the skin and the bursa that forms.

Exostosis due to hammer or claw toes

Hammer toes and claw toes are toe deformities that often occur together with hallux valgus (bunion).

Hammertoe syndrome occurs when the balance of forces in the muscles at the base of the small toe joints is disturbed. As a result, malposition can occur in all three of the following toe joints:

• Metatarsophalangeal joint (MTP joint): This is exclusively a malposition in the direction of the dorsum of the foot (dorsal extension), up to dislocation of the joint.
• Toe joint close to the body (PIP joint): Here, a bending malposition (plantar flexion) and overextension (dorsal extension) can occur.
• Toe joint far from the body (DIP joint): Here, too, a bending malposition (plantar flexion) and overextension (dorsal extension) occur.

Usually there is a combination malposition of these joints, which then leads to descriptive proper names, such as:

• Hammer Toe
• Claw Toe – different versions
• Digitus superductus
• Mallet toe

Due to these malposition’s and overloading, exostoses can also occur in these areas:

A chronic overload as a trigger of the bone protrusion

Even though the triggers for an exostosis vary, an exostosis should always be evaluated as a sign of chronic overloading of the foot - especially when exophytes form in the course of arthrosis. Osteoarthritis itself always represents a situation that arises when the load on the foot is higher than its load-bearing capacity. Causes for this can be, for example, high endurance loads, intensive sports, permanent overweight, but also congenital foot malposition.

What role does incorrect footwear play in the development of an exostosis?

The choice of incorrect footwear is not the cause of the development of an exostosis. However, ill-fitting, too tight, or too high shoes can promote or even aggravate the complaints.

In the case of an exostosis on the foot, care should be taken to ensure that the shoes are comfortable and wide enough and that as little pressure and friction as possible is exerted at the site of the exostosis. If you want to do something good for your feet, you should avoid wearing shoes as often as possible, if your feet do not hurt. Walking barefoot and on soft surfaces can be an effective therapy measure.

If an exostosis is suspected, it is advisable to consult a foot specialist in good time. On the one hand, to first differentiate an exostosis from a ganglion diagnostically and, on the other hand, to approach the corresponding treatment not only symptomatically but also cause-oriented.