Hereditary Multiple Osteochondromas (HMO), also known as Multiple Hereditary Exostoses (MHE), is a rare genetic disorder defined by the development of several benign osteochondromas.
These tumours, which usually develop near the growth plates of long bones, can lead to various complications, including skeletal deformities, joint pain, and, in some cases, a risk of malignant transformation. This article explores the causes, symptoms, and treatment options for hereditary multiple osteochondromas to provide a comprehensive understanding of this rare medical condition.
What is Hereditary Multiple Osteochondromas?
The skeletal condition known as Hereditary Multiple Osteochondromas (HMO) occurs when people develop several osteochondromas, which are bony growths capped with cartilage that appear close to the growth plates of long bones like the femur, tibia, humerus, and forearm bones.
While these osteochondromas are usually benign, they can cause deformities, pain, and limited movement, significantly if they compress nearby tissues like muscles, tendons, or nerves. hereditary multiple osteochondromas are often diagnosed during childhood, as the symptoms become evident when the child begins to grow.
Causes of Hereditary Multiple Osteochondromas
Hereditary multiple osteochondromas is a genetic disorder caused by mutations in either the EXT1 or EXT2 genes, which are involved in the production of heparan sulfate, a substance essential for the proper formation of cartilage and bone. Heparan sulfate plays a critical role in signalling pathways during bone growth and development, and mutations in the EXT1 or EXT2 genes disrupt these pathways, leading to abnormal bone growth and the formation of osteochondromas.
This disorder is inherited in an autosomal dominant pattern, meaning that only one copy of the mutated gene from an affected parent is sufficient to cause hereditary multiple osteochondromas in offspring. While most cases of hereditary multiple osteochondromas are familial, spontaneous mutations can also occur, resulting in cases without a family history.
Epidemiology of Hereditary Multiple Osteochondromas
Hereditary multiple osteochondromas is a rare condition with an estimated prevalence of 1 in 50,000 individuals. However, the frequency varies across populations and may be underreported due to mild cases that go undiagnosed. Both males and females are affected, but males are more likely to experience severe symptoms and complications.
Symptoms typically begin to appear in early childhood, usually before the age of 12, and the number of osteochondromas may increase during periods of rapid growth, such as adolescence.
Symptoms
A person’s age and skeletal development stage, as well as the size, quantity, and location of osteochondromas, all influence the symptoms of hereditary multiple osteochondromas. While some individuals may experience only mild symptoms, others may suffer from significant physical and functional limitations. The common symptoms include:
Bone Pain and Discomfort
Pain is often the earliest symptom, especially when osteochondromas press on surrounding muscles, tendons, or nerves. Pain can intensify during periods of rapid growth, such as adolescence, or with physical activity. In some cases, the discomfort can be constant, impacting sleep and daily activities.
Skeletal Deformities
Large or numerous osteochondromas can cause deformities, particularly in the long bones. It may lead to issues such as bowed legs, short stature, or disproportionate limb lengths. Over time, these deformities can become more pronounced, sometimes resulting in visible limb misalignment that can affect posture and balance.
Restricted Joint Movement
When osteochondromas grow near joints, they can restrict movement, leading to stiffness, reduced range of motion, and difficulty performing daily tasks. Limited mobility can further contribute to muscle weakness around the affected joints, making it harder for individuals to maintain physical activity levels.
Nerve Compression
Osteochondromas that grow near nerves can cause numbness, tingling, or weakness in the affected limb, sometimes leading to nerve damage if not treated. In severe cases, prolonged nerve compression can result in persistent weakness or loss of function, impacting activities that rely on fine motor control or strength.
Treatment Options for Hereditary Multiple Osteochondromas
Treatment for hereditary multiple osteochondromas depends on the severity of symptoms, the number and location of osteochondromas, and the age of the patient. While there is no definitive cure for hereditary multiple osteochondromas, various treatment approaches can help manage symptoms, prevent complications, and improve quality of life.
Non-Surgical Treatments
Here are the non-surgical treatment options:
Pain Management
Pain relievers, such as nonsteroidal anti-inflammatory drugs (NSAIDs), may be used to alleviate pain associated with osteochondromas. Stronger prescription painkillers might be necessary in certain situations, particularly if pain interferes with daily activities. Complementary therapies such as massage, acupuncture, or heat therapy may also be used as part of long-term pain management plans.
Physical Therapy
Physical therapy exercises can improve flexibility, strengthen muscles, and help individuals maintain joint mobility, reducing the risk of stiffness and restricted movement. A tailored therapy plan may focus on specific areas affected by osteochondromas, helping to improve posture, coordination, and overall body mechanisms. Regular therapy sessions can also help manage discomfort and preserve physical function over time.
Regular Monitoring
Regular follow-up with a healthcare provider and periodic imaging studies can help monitor the growth and behaviour of osteochondromas, allowing for early detection of potential complications, such as malignant transformation.
Monitoring is especially important during growth spurts in childhood and adolescence, as osteochondromas may develop or change more rapidly during these periods. Early detection of any suspicious changes can lead to timely interventions that may prevent complications.
Surgical Treatments
Here are the surgical treatment options:
Osteochondroma Resection
Surgical removal of osteochondromas is considered when they cause significant pain, deformities, or functional impairment or if there is a suspicion of malignant transformation. This procedure typically involves removing the entire bony growth along with the cartilaginous cap. In carefully planned cases, the surgery can restore mobility, relieve pressure on surrounding tissues, and improve overall quality of life.
Corrective Surgery for Deformities
In extreme situations, corrective surgeries may be required to address skeletal deformities, such as limb length discrepancies or bowed legs, to improve function and appearance. These procedures may involve bone realignment, growth plate adjustments, or the use of specialised implants. Corrective surgeries are often performed in childhood or adolescence to allow for better outcomes as the skeleton matures.
Nerve Decompression Surgery
Decompression surgery may be required to release pressure and stop more nerve injury if an osteochondroma is compressing a nerve. This procedure helps restore function and avoid long-term nerve problems by reducing symptoms like numbness, tingling, and weakening. To minimise risks and guarantee a positive result, careful surgical planning is necessary, especially if the nerve compression is near a joint or blood vessel.
Conclusion
In conclusion, Hereditary Multiple Osteochondromas is a complex genetic disorder that poses various physical, functional, and emotional challenges for affected individuals. Although there is no cure for Hereditary multiple osteochondromas, early diagnosis and comprehensive management can help alleviate symptoms, prevent complications, and improve quality of life.
Advances in genetics and molecular biology are gradually opening doors to potential new treatments, offering hope for a future where individuals with hereditary multiple osteochondromas can live with reduced symptoms and fewer limitations.
