What Is Leg Length Discrepancy?
Leg length discrepancy (LLD) occurs when one leg is shorter than the other. While small differences are common and usually harmless, larger discrepancies can cause problems with walking, posture, and joint health.
In adults, leg length differences often develop as a result of arthritis. When hip or knee joints wear down unevenly, the bones shift position and the leg can become functionally shorter on the affected side.
Types of Leg Length Discrepancy
Structural LLD
This involves an actual difference in bone length. Causes include:
- Previous fractures that healed improperly
- Bone diseases or infections
- Congenital conditions present from birth
- Surgical procedures that affected bone length
Functional LLD
The bones are the same length, but other factors make one leg appear shorter:
- Hip or knee arthritis causing joint collapse
- Muscle tightness pulling the pelvis out of alignment
- Foot problems like flat feet on one side
- Scoliosis or spinal curvature
In older adults with joint pain, functional LLD from arthritis is the most common type.
Signs and Symptoms
What You Might Notice
- Uneven hips when standing - one side appears higher
- Limping or an altered walking pattern
- Back pain from compensating for the imbalance
- Hip pain on one or both sides
- Knee pain from abnormal stress distribution
- Uneven shoe wear - one sole wears down faster
How It Affects Your Body
When your legs are unequal length, your body compensates:
- Your spine curves to keep your head level
- One hip works harder than the other
- Your knees absorb uneven forces
- Muscles on each side develop differently
These compensations can lead to pain and accelerated wear on your joints over time.
Connection to Advanced Arthritis
Leg length discrepancy often signals that arthritis has progressed significantly. Here is why:
Cartilage Loss and Joint Space Narrowing
As arthritis wears away cartilage in your hip or knee, the joint space narrows. This makes the affected leg functionally shorter.
Bone Changes
Bone spurs and bone remodeling can alter how your joints fit together, changing leg length.
Joint Collapse
In severe arthritis, the joint surfaces may partially collapse, creating measurable length differences.
Why This Matters
Understanding that leg length changes often reflect underlying arthritis helps you:
- Recognize when to seek evaluation
- Understand why treatment of the arthritis itself is important
- Make informed decisions about treatment options
The Role of Imaging
Standing X-Rays
Full-length standing X-rays are the gold standard for measuring leg length. They show:
- Exact difference in leg length
- Where the discrepancy originates (hip, knee, or both)
- The severity of arthritis in each joint
- Whether bone spurs or joint collapse contribute to the difference
Hip and Knee X-Rays
Focused images of individual joints reveal:
- How much joint space remains
- The presence and size of bone spurs
- Bone density and quality
- Alignment of the joint components
When Additional Imaging Helps
Your doctor may order:
- CT scans for precise bone measurements
- MRI to evaluate soft tissues and cartilage
- Bone scans if infection or other conditions are suspected
When to See a Doctor
Schedule an evaluation if you notice:
- One leg appears shorter when you look in the mirror
- You have developed a new limp
- Hip, knee, or back pain accompanies the leg length difference
- Your shoes wear unevenly despite proper fit
- You struggle with activities you could do before
Signs Requiring Prompt Attention
Seek care quickly if you experience:
- Sudden leg length change after a fall or injury
- Progressive difficulty walking or standing
- Severe pain in your hip, knee, or back
- Numbness, tingling, or weakness in either leg
- Inability to bear weight
Treatment Options
Addressing the Discrepancy
Heel lifts and shoe inserts - Custom or over-the-counter lifts can equalize leg length and reduce strain on your joints and spine.
Shoe modifications - A cobbler can add height to one shoe for larger discrepancies.
Physical therapy - Exercises to strengthen core muscles, improve flexibility, and optimize your walking pattern.
Treating the Underlying Arthritis
Since arthritis often causes functional leg length differences:
Viscosupplementation (gel injections) can restore joint lubrication and potentially slow further joint space loss.
Physical therapy strengthens muscles around the joint to improve stability and function.
Corticosteroid injections reduce inflammation contributing to pain and swelling.
Joint replacement surgery - When arthritis is severe, hip or knee replacement can restore leg length and eliminate pain.
Self-Care Strategies
While awaiting evaluation or as part of ongoing management:
Try heel lifts - Inexpensive inserts available at pharmacies can provide temporary relief
Stay active - Low-impact exercises like swimming maintain fitness without stressing joints
Strengthen your core - Strong abdominal and back muscles help compensate for imbalances
Stretch regularly - Flexibility exercises for hips and legs reduce muscle tightness
Use assistive devices - A cane on the longer leg side provides stability
What to Expect
Treatment goals for leg length discrepancy include:
- Reducing or eliminating pain
- Improving your walking pattern
- Preventing further joint damage
- Maintaining independence and activity level
Many people achieve significant improvement through a combination of treatments tailored to their specific situation.
Questions for Your Doctor
- How much difference is there between my leg lengths?
- Is this caused by arthritis, or is there another reason?
- What do the X-rays show about my hip and knee joints?
- Would heel lifts or shoe modifications help me?
- What treatment options address both the leg length difference and my arthritis?
Related Symptoms
- Bone Spurs - Osteophytes that develop around joints
- Joint Deformity - Visible changes to joint shape