Exostosis: osteochondral, calcaneal, knee joint, in dentistry

Exostosis of the femur is excessive growth of bone tissue in a certain area with subsequent protrusion beyond the bone. The neoplasm manifests itself in the form of single or multiple growths. It takes on a linear, spherical, mushroom-like shape (with a “leg” and a cartilaginous cap). Most often it is located in the distal part of the bone under the quadriceps femoris muscle, which is responsible for the functional ability of the knee joint and stabilization of the patella. Exostosis of the femur ranks first among benign tumors of the musculoskeletal system.

In addition to the lower extremities, bulges can form on almost any part of the skeletal base.

And now in more detail what it is - exostosis, what the anomaly is associated with and how to deal with it.

General information

Osteochondroma of bone (synonymous with osteochondral exostosis) is a benign exophytic osteochondral formation, which is located on the outer surface of the bone and consists of a bone base, covered on top with cartilaginous tissue (the so-called cartilaginous cap). It is one of the most common skeletal tumors, accounting for about 20% of all human bone tumors and almost 40% of the totality of benign tumors ( chondroma , osteoma , osteoblastoma , chondroblastoma , osteoid osteoma , etc.).
Morphologically, osteochondroma is a spongy bone with a cortical layer, which is covered with articular-like cartilage, the thickness of which does not exceed 1 cm, and can be attached to the bone with a pedicle or a wide base; the cartilaginous covering of the subchondral endplate is not separated from the underlying bone (Fig. below). In this case, there is a violation of the processes of resorption, remodeling of physiological regeneration of bone tissue, which characterizes pycnodysostosis .

This type of tumor is most common in children and young people (up to 20 years) in whom epiphyseal bone growth has not yet been completed. The focus of osteochondroma can occur anywhere in the skeleton, however, in most cases it is localized in long tubular bones (femur, humerus, tibia), affecting their metaphyseal sections, and the favorite localization is the upper part of the tibia or the lower part of the femur. The approximate incidence of tumors in various bones of the skeleton is: in the femoral part of the leg about 30%; shin bones 15-20%; in the humerus 10-20%. The remaining bones of the skeleton (scapula, collarbone, spine, ribs, pelvic bones, etc.) are affected much less frequently.

Exostoses are quite common in dentistry. Most often, ecostoses in the oral cavity are localized in the area of the alveolar process from the buccal surface or the body of the jaw in the form of tubercles, blunt ridges and protrusions. Exostosis of the gums occurs more often after tooth extraction, trauma, or due to age-related changes in the alveolar ridge. Exostoses of the mandibular bone are most often located on the lingual side in the area of premolars and much less often in the area of molars, incisors and canines. They manifest themselves in the form of a tubercle or ridge, a process, and if they are large in size, they may require not only their removal, but also restoration of the gums (Fig. below).

Osteochondral exostosis in children at the beginning of development is located on the side of the metaphysis near the epiphyseal-cartilaginous plate, and exostosis in older children is located closer to the diaphysis and based on the distance of the exostosis from the epiphysis of the bone, one can judge the timing of its appearance. The growth of most exostoses continues, as a rule, until the onset of synostosis of the epiphysis with the metaphysis (until the end of skeletal growth). ICD-10 code: D16 (benign neoplasms of bones and articular cartilage).

This osteochondral formation can be either solitary (single) or generalized in the form of multiple exostoses. Solitary osteochondromas can have a narrow or wide base, and with multiple lesions, all bone metaphyses are involved in the pathological process in the form of an ovoid/spherical formation, the sizes of which vary widely (from 2 to 12 cm or more), sometimes reaching a large size. This type of tumor is more common in males, and there are cases of family predisposition to the appearance and development of multiple exostoses. At the same time, multiple exostotic osteochondrodysplasia is inherited in an autosomal dominant manner and manifests itself in patients under 20 years of age.

Due to the effect of the tumor on the growth zones of long bones, exostosis can lead to significant shortening of the segments of the lower/upper limb, curvature of the arms/legs, fractures of the extremities and cause early disability of the patient, and the constant experience of one’s inferiority negatively affects the mental and emotional state of patients.

The most dangerous complication of osteochondroma of the bone is the potential for its malignant transformation, usually into chondrosarcoma. At the same time, atypical growth can manifest itself both in the area of the cartilaginous cap of the exostosis tumor, and in the middle part or at the base of the tumor.

Malignancy of exostoses is more common (72%) in patients with multiple forms of exostotic chondrodysplasia, and the prevailing localization of exostoses with atypical growth is predominantly the pelvic bones, less often the ribs, scapula, and spine.

Surgery and rehabilitation for exostosis

Removal of exostosis is carried out by excision of the neoplasm and the sclerotic area to the border with healthy tissues. To avoid relapse or development of bursitis, the periosteum and fibrous capsule are removed together. If the operation is performed correctly, without damaging the growth plate, a small depression remains in the femur. The defect does not require replacement, as it is smoothed out over time due to the process of bone tissue regeneration. Minimally invasive techniques can reduce the rehabilitation period to a minimum.

Resection of numerous exostoses will require bone grafting and/or partial endoprosthetics, with mandatory drainage for 2–3 days. Due to the increased risk of fractures, fixation of the knee joint with orthopedic devices (7–14 days) and limitation of static load (30–45 days) are indicated.

Radical surgical treatment has a high probability of complete recovery. Cutting down protrusions with special tools does not exclude the possibility of reoccurrence.

The prognosis for exostosis is quite favorable. Only one neoplasm in a hundred undergoes malignancy. Patients whose close relatives are susceptible to the formation of osteochondral growths are advised to protect themselves from hypothermia, colds and injuries.

Classification

The classification is based on several characteristics. Based on quantitative characteristics, solitary (single) and multiple (generalized) forms are distinguished.

According to the stages of osteochondroma formation:

The neoplasm is formed from cartilaginous tissue and cannot be detected by palpation.
Ossification of the growth and its increase. The bone tissue is covered with cartilage, and active growth continues.
The growth of the bone part of the tumor stops, but the growth of the cartilaginous “cap” of the tumor may continue. Determined by palpation examination. During physical activity, it can manifest as pain and impaired limb function.

Based on the shape and direction of tumor growth, there are hill-shaped, linear and spherical exostoses.

Causes

The question of the etiology of osteochondromas remains open to this day. A number of authors do not recognize the tumor nature of osteochondromas, but consider it as a violation of the process of enchondral ossification (as a result of dysembryogenesis ). Many authors are inclined to believe that the appearance and development of osteochondroma is associated with a congenital pathology, the development of which continues throughout the entire period of bone growth (that is, the epiphyseal plate is displaced during the formation of the child’s bones even during the intrauterine formation of the skeleton).

Factors that increase the risk of its development include:

Ionizing radiation.
Severe bone bruises and fractures.
Disruptions in the endocrine system.
Infectious diseases.

Symptoms

The symptoms of osteochondrosis are determined by the form of the disease, the size, shape and localization of exostoses, their relationships with surrounding tissues and organs. As a rule, in the solitary form, tumor-like formations of bone density are detected, of various sizes and shapes, motionless in relation to the bone. The skin over them is often unchanged. Since the tumor growth process is slow, in most cases it is asymptomatic and there is no pain. However, osteochondral exostoses of significant size can compress blood vessels/nerve trunks, joints, and cause reactive bursitis/myositis, which causes pain.

Osteochondroma of the femur in the initial stage is asymptomatic. When the size of the tumor reaches significant levels, pain and dysfunction appear. Exostosis of the knee joint, when it reaches a large size and is localized at the end of the tibia, can cause pain, especially in women when walking in high heels. In this area, injury to the adjacent soft tissues of the knee joint may occur with the development of tendinitis or bursitis .

Exostosis of the calcaneus can have different shapes, which determines the clinical picture. If the osteochondral formation of the heel bone has a spherical/mushroom-shaped shape with localization on the back of the heel, then after reaching a size of 3-4 cm, pain appears when walking with the inability to fully step on the foot. At the same time, due to frequent traumatization of the formation by shoes, the skin over it becomes rough, compacted with pronounced abrasions. The pain syndrome is stronger in the morning, and after a while its intensity decreases somewhat. Due to prolonged irritation of the muscular-ligamentous apparatus of the sole of the foot when walking in the evening, swelling appears (Fig. below).

When exostoses are localized in the spinal region and they grow in the direction of the spinal canal, compression of the spinal cord may be observed with corresponding symptoms depending on the location of the compression. In the form of multiple exostotic chondrodysplasia, the disease can manifest itself as short stature, valgus deformity of the knee joints, and clubhandedness. of osteochondroma are common .

Exostoses of the jaw of small size, as a rule, do not cause any complaints and tumors are detected when visiting the dentist. The mouth opens fully. Exostoses of the oral cavity, not fused with the surrounding soft tissues, the mucous membrane above them is mobile, pale pink, without visible pathological changes. As the size of exostoses increases, the mucous membrane becomes thinner, which increases the risk of injury from the edges of the teeth. More unfavorable is the localization of the tumor in the area of the articular process, which causes pain, a displacement of the mental part to the healthy side, there is a restriction in opening the mouth, and a violation of occlusion. The general condition of patients with exostosis of the jaw does not suffer.

Based on the nature of development and clinical course, there are several variants of exostosis, the prognosis of which varies:

Exostosis with “normal” growth activity (grows slowly, the growth of cartilage and the affected bone is balanced. As a rule, such tumors do not increase in size after completion of skeletal growth. The prognosis is favorable with an extremely low probability of malignancy.
Exostoses with high growth activity and uneven bone formation. Growth occurs primarily due to the proliferation of cartilage, since the cartilaginous growth zone is preserved and this process continues even after the completion of the formation of the skeleton. The likelihood of malignancy of exostoses is high.
Malignant exostosis. They transform predominantly into chondrosarcoma / osteogenic sarcoma . The most common localization is the ribs, pelvic bones, scapula, and spine. The prognosis is unfavorable.

Indications for surgery

Treatment of growths with therapeutic methods does not bring results. The only option for getting rid of osteochondral growths is removal.

Considering that benign tumors do not pose a threat to the patient’s life, surgical intervention is resorted to if:

the neoplasm has penetrated deep into the underlying soft tissue or is characterized by rapid growth;
exerts strong pressure on nerve endings and neighboring organs;
leads to limited functional abilities, skeletal deformation;
causes persistent pain and aesthetic discomfort;
promotes the formation of a false joint and the development of inflammation.

If there are no indications, the patient is under medical supervision. Regular assessment of the growth dynamics of newly formed tissues and changes in their structures is carried out.

Tests and diagnostics

The diagnosis is made on the basis of the patient’s complaints, medical history, results of a physical examination and X-ray data in 2 projections, in which the tumor is visualized as an additional shadow with smooth, clear contours, connecting to the bone with a wide base or pedicle. If the cartilaginous cap does not contain calcifications, then it is not visible on the images. Additional methods of instrumental examination are:

CT scan, which makes it possible to track the presence of a connection between the central part of the formation, which is filled with bone marrow contents directly with the medullary canal of the maternal bone.
MRI - allows you to obtain data on the thickness of the cartilage cap, which allows you to determine the nature of the tumor (a thickness of more than 2 cm is a sign of malignant transformation).
Differential diagnosis is carried out with other types of benign tumors ( chondroma , osteoma , osteoblastoma , chondroblastoma , osteoid osteoma ).

List of sources

Zatsepin, S.T. Bone pathology of adults / S.T. Zatsepin. – M.: Medicine, 2001. – 640 p.
Neustadt, E.L. Tumors and tumor-like bone diseases / E.L. Neustadt, A.B. Markochev. – St. Petersburg: Foliant, 2007. – 344 p.
Epidemiology of skeletal tumors: educational manual / Chernyakova Yu.M., Ivanov S.A., Yadchenko V.N. – 2012.
Volkov, M.V. Bone diseases in children / M.V. Volkov. – M: Medicine, 1985. – 511 p.
Lanzman Yu.I. Benign tumors / Bone tumors. – Tomsk: Tomsk University Publishing House, 1990. – P. 88158.

Symptoms

At the initial stage, exostoses form unnoticeably. With slow growth over many years, patients may not be aware of pathological changes until they are accidentally discovered on x-rays. As the growths increase in size, they are determined visually and by palpation.

The clinical picture of osteoid exostoses is different. In this case, growths on the bones initially manifest themselves with limited pain in the area close to the lesion. The discomfort is similar to muscle pain syndrome. The discomfort gradually progresses. Intense pain appears spontaneously, temporarily decreases or disappears under the influence of an anesthetic.

With any type of bone exostosis, if it has formed close to the joint capsule, fluid accumulation, swelling, and sometimes local hyperemia and hyperthermia are noted in the lesion. The growths can stimulate the development of reactive arthritis and synovitis. The growth of neoplasms provokes deformation and shortening of the limb, forced lameness, limited range of motion, and atrophy of muscle tissue.

In childhood and adolescence, the close location of the protrusions relative to the growth zone leads to skeletal asymmetry due to the acceleration of bone growth.

In children, spontaneous resolution of exostoses is observed upon completion of active maturation of bone tissue.