What causes your legs to bow as you get older? A look into adult genu varum

Approximately 14% of people aged 60 and older have osteoarthritis, a leading contributor to leg deformities. This and other age-related conditions can help explain what causes your legs to bow as you get older, a phenomenon known medically as genu varum.

Quick Summary

Several underlying medical conditions and factors can cause legs to bow in older adults, most notably progressive osteoarthritis and Paget's disease, which lead to bone and joint deterioration over time. The condition is often exacerbated by mechanical stress on the knees, past injuries, and nutritional deficiencies.

Key Points

• Osteoarthritis is a primary cause: Uneven cartilage wear in the knees, particularly on the inner side, is a common reason legs bow in older adults.

• Paget's disease weakens bones: This metabolic condition disrupts bone remodeling, creating weaker bones that can bend under the body's weight.

• Nutritional deficiencies play a role: A lack of Vitamin D, leading to osteomalacia, can soften bones and cause bowing in adults.

• Past injuries can resurface: Fractures near the knee that healed improperly can lead to gradual worsening of leg alignment over time.

• Treatment options vary: Management ranges from non-surgical methods like orthotics and physical therapy to surgical correction via osteotomy or knee replacement for more severe cases.

• Weight management is crucial: Reducing excess body weight significantly decreases the mechanical stress on aging knee joints.

The Progression of Genu Varum in Adulthood

While infants are often born with a degree of bowleggedness that typically resolves itself, the onset of genu varum later in life is a different and often more concerning matter. In older adults, bowing is not a natural part of aging but a symptom of an underlying condition affecting the bones and joints. Understanding the causes is the first step toward effective management and treatment.

Osteoarthritis: The Most Common Culprit

Osteoarthritis (OA) is the most frequent cause of leg bowing in older adults. This degenerative joint disease involves the breakdown of cartilage that cushions the ends of bones.

• Uneven Wear and Tear: Over many years, a lifetime of weight-bearing can cause the cartilage to wear away unevenly. In the case of genu varum, the cartilage on the inner (medial) side of the knee joint degenerates more rapidly than the outer (lateral) side.
• Increased Compressive Force: This uneven loss of cartilage shifts the weight-bearing axis, placing an excessive compressive force on the medial compartment of the knee. A varus deformity of just 5 degrees can increase the load on the inner knee significantly.
• Bone Remodeling: In response to the increased mechanical stress, the underlying bone remodels and shifts, further increasing the outward angle of the leg over time.
• Varus Thrust Gait: The instability caused by this process can lead to a 'varus thrust' gait, where the knee displaces laterally during walking.

Paget's Disease of Bone

Paget's disease is another significant cause of adult-onset genu varum, primarily affecting individuals over 50. This chronic condition disrupts the body's normal bone remodeling process.

• Disrupted Remodeling: In a healthy person, old bone is broken down and replaced by new bone in a tightly regulated cycle. In Paget's disease, this process is abnormally rapid.
• Weaker, Softer Bone: The resulting new bone is softer, weaker, and more prone to bending and breaking. When this affects the weight-bearing bones of the legs, such as the tibia or femur, it can cause them to bow.
• Deformity and Complications: Bowing is a direct result of the weakened bone giving way to the stress of body weight. The enlarged and misshapen bones can also cause pain, increase fracture risk, and put additional stress on nearby joints, leading to secondary osteoarthritis.

Comparison of Major Causes: OA vs. Paget's Disease

Feature	Osteoarthritis (OA)	Paget's Disease of Bone
Mechanism	Uneven cartilage loss shifts weight-bearing axis.	Disrupted bone remodeling creates weaker, softer bone.
Primary Impact	Joint cartilage and underlying bone.	Bone structure and integrity.
Age of Onset	Typically begins after age 50.	Primarily affects older adults, often after age 50.
Progression	Gradual worsening with increased pain and instability.	Progressive bone softening and deformity over time.
Related Symptoms	Knee pain, stiffness, reduced range of motion.	Bone pain, enlarged head, hearing loss.

Other Contributing Factors

In addition to the primary conditions, several other issues can contribute to or worsen bowed legs in older adults.

1. Osteomalacia (Adult Rickets): Caused by a severe, prolonged vitamin D deficiency, this condition results in soft, weak bones that can bow under weight. While less common today, it can still affect older adults with limited sun exposure or dietary deficiencies.
2. Improperly Healed Fractures: A previous fracture to the leg bones, particularly near the knee, can heal with a slight angular deformity. Over many years, this can worsen and lead to noticeable bowing.
3. Chronic Stress and Occupation: Certain jobs or activities that place constant, uneven stress on the knee joints, such as those that involve repetitive kneeling or heavy lifting, can exacerbate the development of genu varum.
4. Obesity: Carrying excess weight places significantly more stress on the knee joints, accelerating cartilage wear and increasing the risk of OA and other deformities.

Management and Treatment Options

For adults with genu varum, the primary goals of treatment are to manage pain, improve mobility, and prevent further progression. An orthopedic specialist can determine the best course of action based on the underlying cause and severity.

• Non-Surgical Treatments:
  • Physical Therapy: Strengthening the muscles around the knee, hip, and core can improve stability and gait.
  • Orthotics: Shoe inserts or custom-made braces can help redistribute pressure and improve alignment.
  • Weight Management: Losing excess weight is crucial for reducing stress on the knee joints.
  • Medications: Pain relievers and anti-inflammatory drugs can help manage symptoms associated with arthritis.
• Surgical Interventions:
  • Osteotomy: For more severe cases, an osteotomy is a surgical procedure to cut and reshape the bone to correct the alignment. It is often used to prevent or delay the need for a total knee replacement.
  • Total Knee Replacement (TKR): In advanced cases of osteoarthritis where significant joint damage has occurred, a TKR can effectively straighten the leg and relieve pain.

Proper diagnosis is key, so if you notice your legs bowing, it's important to consult a healthcare professional. For more information on bone and joint health, visit the Bone Health & Osteoporosis Foundation for authoritative resources.

Conclusion

Bowing of the legs as you get older is not an inevitable part of aging but a sign of underlying orthopedic or metabolic issues. The most common causes include degenerative osteoarthritis and Paget's disease, both of which compromise the integrity and alignment of the knee joint and leg bones over time. Early diagnosis, combined with lifestyle changes, physical therapy, and—when necessary—medical intervention, can effectively manage symptoms and slow the progression of the condition, helping to maintain mobility and quality of life.

Frequently Asked Questions

Can bowed legs be corrected in adults without surgery?

While surgical correction is often needed for significant deformities, non-surgical methods can help manage symptoms and slow progression. These include physical therapy, weight management, and using orthotics or braces to improve alignment and reduce stress on the knees.

Are bowed legs painful in older adults?

Yes, unlike in young children, bowed legs in adults can cause significant pain. The uneven stress on the knee joints, often caused by advanced osteoarthritis, leads to discomfort, swelling, and reduced range of motion.

What's the difference between bowlegs and knock-knees?

The medical term for bowlegs is genu varum, where the legs curve outward, causing a gap between the knees. Knock-knees, or genu valgum, is the opposite, where the knees touch but the ankles are apart.

How is adult-onset genu varum diagnosed?

A doctor will perform a physical examination and often use imaging, such as X-rays, to assess the alignment of the legs and the condition of the knee joints. This helps determine the underlying cause and severity.

Can exercise help with bowed legs?

Specific exercises prescribed by a physical therapist can help strengthen the muscles that stabilize the knees and improve gait. While exercise won't change the bone shape in adults, it can significantly improve function and reduce pain.

Is it possible to prevent your legs from bowing with age?

While it may not be entirely preventable, managing risk factors can help. This includes maintaining a healthy weight, ensuring sufficient vitamin D intake, and strengthening the knee-stabilizing muscles to reduce joint stress over time.

Can bowed legs get worse with age if left untreated?

Yes, if the underlying cause is a progressive condition like osteoarthritis or Paget's disease, the bowing can worsen over time. This can increase pain, instability, and the risk of further joint damage.