Leg-Length Discrepancy

Leg-length discrepancy (LLD) refers to a condition in which one leg is shorter than the other. This difference in leg length may be minimal and go unnoticed, or it can be more pronounced, causing a noticeable limp, discomfort, or musculoskeletal problems (1). LLD can be categorized into two primary types: structural and functional. Structural discrepancies arise from actual differences in bone length, while functional discrepancies are due to posture or other compensatory mechanics, such as pelvic tilt or joint contractures.

LLD can affect individuals of all ages, from children with congenital conditions to adults dealing with injury-related shortening. Depending on the severity, it can influence gait, spinal alignment, and overall biomechanics, sometimes leading to chronic pain or reduced quality of life (1).

Symptoms

The symptoms of leg-length discrepancy vary depending on the extent of the discrepancy and whether it is structural or functional. Common symptoms include:

• Visible Limping: A shorter leg can cause an asymmetrical gait or limp.
• Uneven Hips or Shoulders: The pelvis may tilt, making one hip or shoulder appear higher.
• Lower Back Pain: LLD can strain the lumbar spine and surrounding muscles.
• Hip, Knee, or Ankle Pain: Imbalanced weight distribution often leads to joint pain or overuse injuries.
• Fatigue: Walking or standing may be more tiring due to inefficient movement.
• Frequent Tripping or Balance Issues: Especially in more significant discrepancies.

Mild discrepancies may be asymptomatic but still affect posture or performance, particularly in athletes (1).

Causes

The causes of LLD are diverse and can be broadly classified as congenital or acquired

• Congenital Causes
  • Birth defects affecting bone development
  • Hemihypertrophy (one side of the body grows faster)
  • Developmental dysplasia of the hip (DDH)
• Acquired Causes
  • Bone fractures that heal improperly
  • Growth plate injuries in children
  • Infections affecting bone growth (e.g., osteomyelitis)
  • Neurological conditions (e.g., cerebral palsy)
  • Joint or bone surgery (e.g., hip replacements)
  • Tumors or their treatment, such as radiation

Functional LLD, while not due to bone length differences, can result from muscle imbalances, scoliosis, pelvic obliquity, or arthritis.

Risk Factors

Several risk factors can predispose individuals to leg-length discrepancy

• Childhood Bone Injuries: Injuries that damage the growth plates can lead to uneven growth (2).
• Congenital Conditions: Disorders like fibular hemimelia or congenital hip dislocation.
• Previous Surgeries: Especially orthopedic surgeries on the lower limbs.
• Infections and Inflammation: Such as bone infections in childhood.
• Neuromuscular Disorders: Conditions that alter posture and muscle function.
• High-impact Sports: Athletes may develop functional LLD due to repetitive strain and muscle imbalance.

Family history may also play a role in some congenital discrepancies.

Diagnosis

Diagnosing LLD begins with a thorough clinical evaluation and is often confirmed with imaging (2). The diagnostic process typically includes

1. Physical Examination
   • Measurement from the pelvis to the ankle or knee
   • Gait analysis
   • Assessment of pelvic tilt and spinal curvature
2. Imaging Studies
   • X-rays: Standard for measuring actual bone lengths.
   • CT Scan or MRI: Used when detailed bone or soft tissue imaging is needed.
   • Scanograms: Specialized X-rays for precise measurement of limb length.
3. Functional Assessments
   • Analysis of muscle strength and joint mobility
   • Observation of walking and posture

Measurement errors can occur, so multiple methods are often used to ensure accuracy.

Treatment Options

The treatment for LLD depends on the severity of the discrepancy, symptoms, and whether the condition is expected to progress (as in growing children) (3). Treatment can be non-surgical or surgical

Non-Surgical Treatment

• Shoe Lifts: Custom heel or sole lifts help balance gait and relieve symptoms.
• Physical Therapy: Helps improve posture, strength, and alignment.
• Orthotics: Used for functional LLD to address pelvic tilt or foot abnormalities.
• Regular Monitoring: In children, regular assessments are crucial to track progression.

Non-surgical options are generally suitable for discrepancies under 2 cm, especially if symptoms are mild.

Surgical Treatment

Surgery is usually considered when the discrepancy is

• Greater than 2–2.5 cm and causing symptoms
• Expected to worsen in growing children

Surgical options include

• Epiphysiodesis: A procedure to slow growth in the longer leg to allow the shorter leg to catch up (3).
• Leg Lengthening Surgery: Involves cutting the bone and using an external or internal device to gradually lengthen it.
• Shortening Procedures: Removing a segment of bone from the longer leg (less common).
• Bone Transport or Reconstruction: Used in complex cases with bone loss.

Surgical intervention requires long-term commitment, rehabilitation, and carries risks such as infection, nerve damage, or joint stiffness.

Living With or Prevention

Living with LLD often requires long-term management, especially in individuals with mild discrepancies or those not opting for surgery (3).

Lifestyle Adjustments

• Use of Shoe Inserts: These help alleviate symptoms and prevent further musculoskeletal problems.
• Regular Physical Therapy: Maintains strength and flexibility, especially in the hips, knees, and spine.
• Posture Awareness: Ergonomic adjustments and posture correction reduce strain.
• Activity Modification: Avoiding high-impact activities that may worsen symptoms or imbalance.

Preventive Measures

While not all forms of LLD can be prevented, certain steps may reduce risk:

• Prompt Treatment of Pediatric Bone Injuries: Reduces the risk of growth plate damage.
• Regular Screening in High-risk Children: Particularly those with congenital or neuromuscular conditions.
• Postoperative Monitoring: After leg or joint surgery, ensuring proper healing and symmetry.
• Early Intervention in Scoliosis or Pelvic Tilt: Prevents compensatory LLD from becoming structural.

References

1. Applebaum A, Nessim A, Cho W. Overview and Spinal Implications of Leg Length Discrepancy: Narrative Review. Clin Orthop Surg. 2021 Jun;13(2):127-134. doi: 10.4055/cios20224. Epub 2021 May 18. PMID: 34094002; PMCID: PMC8173231.
2. Alfuth M, Fichter P, Knicker A. Leg length discrepancy: A systematic review on the validity and reliability of clinical assessments and imaging diagnostics used in clinical practice. PLoS One. 2021 Dec 20;16(12):e0261457. doi: 10.1371/journal.pone.0261457. PMID: 34928991; PMCID: PMC8687568.
3. Vogt B, Gosheger G, Wirth T, Horn J, Rödl R. Leg Length Discrepancy- Treatment Indications and Strategies. Dtsch Arztebl Int. 2020 Jun 12;117(24):405-411. doi: 10.3238/arztebl.2020.0405. PMID: 32865491; PMCID: PMC7477698.