Table of Contents
Description
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An osteochondroma is a common developmental abnormality of the peripheral growth plate that results in a lobulated outgrowth of cartilage and bone from the metaphysis.
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Appears as a cartilage-capped bony projection from the metaphysis of long bones
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Can occur in any bone that develops from enchondral ossification
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Most commonly occurs in:
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Long bones, usually the proximal or distal femur, proximal tibia, pelvis, or scapula
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10-25-year-old persons (stops growing at skeletal maturity)
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Growth of the lesions parallels that of the patient.
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Classification:
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Solitary osteochondroma (nonheritable)
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Multiple hereditary exostoses (autosomal dominant):
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Osteochondromatosis
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Diaphyseal aclasis
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Synonym: Osteocartilaginous exostosis
Epidemiology
Incidence
No substantial difference in frequency between males and females
Prevalence
This most common benign bone lesion comprises 40% of all benign bone tumors .
Risk Factors
Genetics
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Multiple hereditary exostoses often is inherited in an autosomal dominant manner.
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To date, 3 different genetic mutations have been isolated:
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EXT 1
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EXT 2
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EXT 3
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Etiology
The cause of an osteochondroma most likely is a detached portion of the growth plate that grows on the surface of the bone.
Diagnosis
Osteochondroma Signs and Symptoms
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Symptoms result from pressure on adjacent nerves and muscle and from local irritation.
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Hard, painless, fixed mass
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Associated symptoms of tissue or nerve irritation
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The skeletal deformity is secondary to undergrowth of the affected bones, with narrower bones being affected more seriously.
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Therefore, the tibia and radius grow longer than the ulna and fibula.
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This phenomenon produces valgus at the knee, ankle, and elbow in some patients.
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Physical Exam
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Note any hard, painless, fixed mass in the metaphyseal region of the fastest growing bones; the region around the knee is the most common.
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Height in most patients falls in the low-normal range.
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Group findings occur in 4 major categories:
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Local impingement, which may include peroneal palsy and soreness of the muscles about the knee
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Valgus at knee, ankle, elbow, and wrist (variable)
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Limb-length inequality
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ROM may be limited secondary to the presence of the osteochondroma.
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Physical examination and radiography should confirm the diagnosis.
Tests
Lab
Blood tests are not altered by this condition.
Imaging
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Radiography:
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Plain films typically depict a compact pedunculated or sessile protuberance of bone.
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The well-defined lesion projects from the metaphysis.
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CT scans are helpful in locations that are difficult to image, such as the scapula, pelvis, and proximal femur.
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MRI scans can be used when a suspicion of malignancy is present.
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The size of the cartilage cap can be measured (a cap >1 cm is worrisome for malignancy).
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Symptomatic bursae can be detected with MRI.
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MRI can detect soft-tissue masses.
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Pathological Findings
Normal hyaline cartilage undergoes normal enchondral ossification, occurring on the end of a stalk or ridge of bone.
Differential Diagnosis
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Surface chondrosarcoma
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Parosteal osteosarcoma
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Periosteal chondroma
Osteochondroma Treatment
General Measures
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Local measures or analgesics are indicated for minor aches.
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Medical treatment:
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The lesion may be left untreated unless it is symptomatic.
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It should be followed clinically, because a 1-10% risk of malignant transformation to chondrosarcoma is present in persons with multiple hereditary exostoses .
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Activity
Activity is allowed as tolerated.
Special Therapy
Physical Therapy
Not usually necessary
Medication
Tylenol or NSAIDs may be used by the patient with occasional symptoms.
Surgery
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Surgical resection of symptomatic lesions is successful with minimal morbidity.
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In patients with the multiple hereditary exostoses form of the disorder, new lesions may form in multiple areas, and they may grow.
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Osteotomies and physeal stapling may be done for angular disturbances.
Follow-up
Prognosis
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The prognosis is good.
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The chance of recurrence after excision of a solitary lesion is very small.
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The risk of malignant transformation of isolated osteochondromas is even lower.
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Patients with multiple hereditary exostoses have a 1-10% risk of malignant transformation .
Complications
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Fracture may occur during the first 3 months after removal of an osteochondroma.
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Vascular or neurologic injury during surgery may occur if the osteochondroma is associated closely with these structures.
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Occasionally, the stalk may fracture.
Patient Monitoring
Patients should be followed regularly (for 1-2 years) for angular disturbances, limb-length inequality, or serious problems from pressure of lesion so they can be treated in a timely fashion before more complex intervention is needed.
Miscellaneous
Codes
ICD9-CM
756.4 Osteochondroma
Patient Teaching
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Reassure the patient about the benign nature of the lesions.
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Teach adults to be alert for growth or new onset of pain in osteochondroma, which may be a sign of a malignant transformation.
FAQ
Q: Is it necessary to remove all osteochondromas?
A: In general, if the patient is asymptomatic, surgical removal is not necessary.
Q: What is the risk of malignant degeneration, and are the resultant cancers treatable?
A: The risk of malignancy in an isolated osteochondroma is extremely low, and the prognosis for the resulting low-grade chondrosarcomas is excellent.
Q: How are patients with multiple hereditary exostoses followed to check for malignant degeneration?
A: Patients are queried about new masses or pain. Plain radiographs, CTS, or MRIs can be used to monitor exostosis in the axial skeleton or large lesions in the extremities.
Appointment
If you would like an appointment / review with our osteochondroma specialist in Singapore, the best way is to call +65 6664 8135 or click here to book an appointment at the clinic. If you would like to speak to one of our clinicians first about e.g. knee osteochondroma, osteochondroma treatment, osteochondroma pain, tibia osteochondroma – then please contact feedback2@bone.com.sg or SMS/WhatsApp to +65 6664 8135.
Rest assured that the best possible care will be provided for you.
