Osteoporosis – Causes, Symptoms, Treatments

What is Osteoporosis?

Osteoporosis is a disease that weakens bones, making them more likely to break. It develops slowly over several years and is often only diagnosed when a fall or sudden impact causes a bone to break (fracture). 

Bones are living tissues that constantly renew themselves. In healthy bone, new bone is formed at about the same rate as old bone is broken down. But in osteoporosis, this balance is tipped. More bone is broken down than formed, which leads to a loss of bone density and strength.

Osteoporosis can cause bones to become weak and fragile, making them more likely to break from a fall or even a minor bump. The most common fractures in people with osteoporosis occur in the hip, spine, and wrist.

Osteoporosis is a common condition, especially among older adults. It is estimated that over 54 million people in the United States either have osteoporosis or have low bone mass that puts them at high risk for the disease. Women are more likely to develop osteoporosis than men, especially after menopause.

Which Bones are Most Susceptible to Osteoporosis?

Osteoporosis has a specific target in the body: bones with high turnover. These are bones that are constantly undergoing remodeling, where old bone is broken down in a process called bone resorption and replaced with new bone. This remodeling process is essential for maintaining bone strength and adapting to mechanical stresses. 

Bone resorption is a natural process in our bodies where specialized cells, called osteoclasts, break down old and damaged bone tissue. This breakdown releases minerals, like calcium and phosphate, back into the bloodstream for the body to use elsewhere. Normally, this process is balanced by bone formation by other cells called osteoblasts.

However, in osteoporosis, this balance is disrupted. Bone resorption outpaces bone formation, leading to a net loss of bone density and weaker bones. This makes them more susceptible to fractures, even from minor falls or bumps.

• Increased Activity of Osteoclasts: In osteoporosis, various factors can cause osteoclasts to become overactive, breaking down bone tissue at an accelerated rate. This could be due to hormonal changes, certain medical conditions, or medications.
• Decreased Bone Formation: Bone formation by osteoblasts may also be impaired in osteoporosis. This can be caused by deficiencies in calcium and vitamin D, both essential nutrients for building strong bones.
• Net Loss of Bone Density: With resorption outpacing formation, the overall bone density starts to decline. This decrease in density weakens the bone structure, making it more prone to fractures.

The hip bone (femur) is a prime target because it’s a weight-bearing bone. It constantly supports the upper body’s weight and experiences significant stress during activities like walking, climbing stairs, or getting up from a chair. This high turnover rate makes it vulnerable when the bone remodeling process becomes imbalanced in osteoporosis.

The vertebrae in the spine are another area susceptible to osteoporosis due to their high remodeling activity. They are constantly under stress from supporting the upper body and the twisting and bending motions of the spine. When bone formation can’t keep up with resorption in osteoporosis, these vertebrae become weak and prone to compression fractures, which can cause pain, height loss, and a curved spine (kyphosis).

The bones in the wrist (distal radius) are also susceptible due to their cancellous bone structure. Cancellous bone, also known as trabecular bone, is a spongy type of bone with a high surface area for rapid bone remodeling. This makes it more vulnerable to the loss of bone density in osteoporosis compared to cortical bone, the denser outer shell of most bones. Additionally, the wrist is often the point of impact when trying to break a fall, further increasing the risk of fracture.

Other factors influencing fracture sites:

• Fall patterns: Falls are a major cause of fractures in osteoporosis, and the body position during a fall can influence the fracture site. For example, a fall forward might lead to a wrist fracture, while a fall backward might impact the spine.
• Bone geometry: The inherent shape and size of some bones can make them more susceptible to fractures. For example, the slender neck of the femur in the hip is a weak point even in healthy bones.

Symptoms of Osteoporosis

Osteoporosis is often called a “silent disease” because typically there aren’t any noticeable symptoms in the early stages. The first sign of osteoporosis for many people is actually a bone fracture.

However, there can be some subtle signs that might indicate bone loss due to osteoporosis. These are generally not specific to osteoporosis and can be caused by other things, but if you experience any of them it’s important to talk to your doctor to get checked for osteoporosis:

• Loss of height: This can happen gradually over time and may not be noticeable at first. A difference of more than an inch compared to your younger height could be a sign.
• Changes in posture: A stooped posture or a condition called kyphosis, where the spine curves forward in the upper back, can be caused by vertebral fractures in the spine.
• Back or neck pain: Vertebral fractures can also cause pain in the back or neck.

Some other possible indicators, though less common and not entirely specific to osteoporosis, include:

• Receding gums: This can be a sign of underlying bone loss throughout the body.
• Weaker grip strength: Reduced grip strength may suggest a loss of bone density in the hands and wrists.
• Brittle fingernails: While not a definitive sign, some people with osteoporosis report experiencing more brittle nails.

Long Term Complications of Osteoporosis

Osteoporosis, if left untreated, can lead to several long-term complications that significantly impact a person’s mobility, independence, and overall quality of life. Here’s a breakdown of the key complications:

Increased Risk of Fractures is the most prominent long-term complication of osteoporosis. The weakened bones are highly susceptible to fractures, even from minor falls or bumps.

The most common fracture sites include:

• Hip: Hip fractures are a serious complication, often requiring surgery (hip replacement) and extensive rehabilitation. Regaining mobility after a hip fracture can be challenging, and some individuals may require long-term care.
• Spine (Vertebrae): Vertebral fractures can cause chronic pain, height loss, and a stooped posture (kyphosis). These fractures can also impinge on nerves, causing pain and radiating symptoms.
• Wrist: While less debilitating than hip fractures, wrist fractures can still cause pain and limitations in hand and arm function.

Fractures caused by osteoporosis are often painful and take time to heal. Chronic pain, especially in the back from vertebral fractures, can significantly limit mobility and affect daily activities. The fear of falling and sustaining another fracture can also lead people with osteoporosis to become more withdrawn and restrict their activities, further impacting mobility and overall well-being.

Vertebral fractures in the spine can cause the vertebrae to collapse, leading to a characteristic stooped posture known as kyphosis. This curvature of the spine can not only be aesthetically displeasing but also cause difficulty breathing and digestive problems.

The limitations in mobility and pain caused by osteoporosis can significantly impact a person’s ability to live independently. Daily activities like dressing, bathing, and housework can become challenging, and some individuals may require assistance or long-term care facilities.

Chronic pain, limitations in mobility, and the fear of falling can take a toll on a person’s mental well-being. Depression and anxiety are common among people with osteoporosis Studies have shown an increased risk of mortality, particularly after hip fractures. Complications from surgery and the challenges of rehabilitation can contribute to this risk.

Causes of Osteoporosis

Osteoporosis develops due to an imbalance in the body’s natural process of bone remodeling. Normally, our bones are constantly undergoing renewal. Specialized cells break down old bone tissue (resorption) and new bone cells form new tissue (formation). In healthy adults, these processes happen at a roughly equal rate. However, with osteoporosis, the resorption outpaces formation, leading to a net loss of bone density and weaker bones.

Several factors can contribute to this imbalance and increase the risk of osteoporosis. As we age, bone formation naturally slows down, while bone resorption continues at a similar rate. This age-related decline is a major risk factor for osteoporosis.

Women are more susceptible to osteoporosis after menopause due to a decline in estrogen production. Estrogen plays a vital role in regulating bone remodeling, and its decrease accelerates bone resorption. Men also experience a gradual decline in testosterone levels with age, which can contribute to  bone loss, although to a lesser extent than in women.

Another cause of this condition is a deficiency in Calcium and Vitamin D. Calcium is the primary mineral component of bone, and vitamin D is essential for calcium absorption. Deficiencies in either can hinder bone formation and contribute to osteoporosis.

Certain medical conditions, such as hyperthyroidism, rheumatoid arthritis, and celiac disease, can disrupt bone metabolism and increase the risk of osteoporosis. Long-term use of medications like corticosteroids (used to treat various inflammatory conditions) can also weaken bones.

Other Factors

Lifestyle Factors:

• Diet: A diet low in calcium and vitamin D can contribute to bone loss.
• Inactivity: Weight-bearing exercises help stimulate bone formation. People with sedentary lifestyles are at a higher risk of osteoporosis.
• Smoking: Smoking disrupts bone formation and healing, increasing the risk of osteoporosis.
• Excessive Alcohol Consumption: Heavy alcohol consumption can interfere with calcium absorption and bone metabolism.

Family History: Having a family history of osteoporosis increases your risk. If a parent or sibling has osteoporosis, you’re more likely to develop it as well.

Race and Ethnicity: White and Asian people are at higher risk for osteoporosis compared to Black and Hispanic people. The reasons for this ethnic disparity are complex and not fully understood but may be linked to genetic factors and vitamin D levels.

How is Osteoporosis Diagnosed?

Osteoporosis itself often doesn’t cause obvious symptoms early on. The first sign for many people is actually a bone fracture. However, doctors can diagnose osteoporosis through a combination of methods:

1. Medical History and Risk Assessment: Doctors will discuss your medical history, including any family history of osteoporosis, and your lifestyle habits such as diet, exercise, and smoking. This conversation helps assess your overall risk for developing the disease.
   
   
2. Physical Examination: A physical exam might reveal signs that could suggest osteoporosis, like a stooped posture or a loss of height. However, a physical exam alone isn’t diagnostic of osteoporosis.
   
   
3. Bone Density Scan (DXA): This is the primary tool for diagnosing osteoporosis. It uses a specialized X-ray to measure bone mineral density (BMD) in the hips and spine, the most common fracture sites. The DXA scan results are compared to reference standards to determine bone density and diagnose osteoporosis or a precursor condition called osteopenia (bone loss that isn’t yet osteoporosis). The DXA scan compares your BMD to that of a healthy young adult. The T-score reflects the following comparison. 

• A T-score above -1 is considered normal bone density.
• A T-score between -1 and -2.5 suggests osteopenia, indicating bone loss but not yet osteoporosis.
• A T-score below -2.5 is generally considered osteoporosis.

Other Imaging Tests (less common):

• X-rays: Although not a primary diagnostic tool for osteoporosis itself, X-rays might be used to identify existing fractures that could indicate the disease.
• CT scans: In some cases, a CT scan might be used to measure BMD, but DXA is generally preferred due to its lower radiation exposure.

How is Osteoporosis Treated?

Osteoporosis treatment focuses on two main goals: preventing further bone loss and reducing the risk of fractures. 

Some medications are often prescribed for use in osteoporosis treatment. Bisphosphonates are the most commonly prescribed medications for osteoporosis. They work by slowing down the rate of bone breakdown (resorption). Examples include alendronate (Fosamax) and risedronate (Actonel).

RANK ligand inhibitors are newer medications that target a protein involved in bone resorption. Denosumab (Prolia) is an example of a RANK ligand inhibitor. Other options include Teriparatide (Forteo) is a medication that stimulates bone formation and is used in some cases of osteoporosis. Selective estrogen receptor modulators (SERMs) like raloxifene (Evista) may be helpful for some women after menopause.

Calcium is the primary mineral component of bone, and ensuring adequate intake is crucial. Rich dietary sources include dairy products, leafy green vegetables, and calcium-fortified foods. Doctors may also recommend calcium supplements. Vitamin D is essential for calcium absorption. Sunlight exposure promotes vitamin D production in the skin, but dietary sources like fatty fish and vitamin D-fortified foods can also contribute. Vitamin D supplements are often recommended to ensure sufficient levels.

Regular weight-bearing exercise is vital for maintaining bone strength and stimulating bone formation. Weight-bearing exercises like walking, jogging, dancing, and strength training put stress on bones, which helps to keep them strong. Balance and coordination exercises can also be helpful to prevent falls, a major risk factor for fractures in people with osteoporosis.

Smoking weakens bones and hinders healing. Quitting smoking is essential for bone health and overall well-being. Excessive alcohol consumption can interfere with calcium absorption and bone metabolism. Moderation or abstinence from alcohol is recommended for people with osteoporosis. Falls are a major concern for people with osteoporosis. Modifications like installing grab bars in bathrooms, removing tripping hazards, and improving lighting can help to prevent falls.