What is a Leg Length Discrepancy ?
Leg length discrepancy is defined as a condition in which the lower extremities are noticeably unequal in length. They can be classified as either:
Structural – Resulting from bony structure unequal in length.
Functional – Asymmetry of the lower extremities causes by mal-position or muscle length/shortening.
What Causes Leg Length Discrepancy ?
Common causes of structural leg length discrepancy:
- Developmental abnormalities
- Fractures/trauma to the growth plate prior to skeletal maturity
- Degenerative disorders
- Legg-calve perthes disease
- Cancer or neoplastic changes
Common causes of functional leg length discrepancy:
- Shortening of soft tissue
- Joint contractures
- Ligament laxity
- Axial malalignments
- Foot bio-mechanics (such as excessive ankle pronation)
What is Considered Significant ?
The medical field is not consistant as to what is considered clinically significant. Globally, leg length inequalities can be described as mild (0-30 mm), moderate (30-60 mm), and severe (>60 mm).
As a manual therapist, a leg length discrepancy can be found on most people. The difficult part is determining where the discrepancy is coming from, and if it is playing a significant role in pain production.
How to Assess for Leg Length Discrepancy?
The gold standard in assessing leg length discrepancy is the use of radiography evidence. The 4 common methods include: teleroentgenography, orthoroentgenography, scanography and computed tomography (CT scan). Research has proven these methods to be the most accurate and reliable, although the majority of therapist do not have access to these scans, so they must rely on clinical examination findings.
Clinical assessments include measuring between two bony landmarks, often being the anterior superior iliac spine (bony part of the hip) to the medial malleoli (inside of the ankle). Other clinical examinations may include palpating and “eye-balling” pelvic and hip landmarks in standing, sitting and lying positions. Keep in mind that these clinical tests are not considered reliable.
How to Treat Leg Length Discrepancies ?
Once again, finding an ‘apparent’ leg length discrepancy is common. The difficult part is determining where it is coming from and if it is playing a role in pain production. The body is fantastic at finding ways to compensate for discrepancies, although over time, this may put certain structures under more stress, and lead to an injury and/or pain.
Interventions can be classified as surgical or non-surgical treatment.
Surgical intervention is often considered for severe and for some moderate leg length discrepancies. Non-surgical treatment such as physiotherapy is often considered for mild and moderate leg length discrepancies.
Physiotherapy intervention for leg length discrepancy will depend on what is found during the assessment, and if it is thought to be structural or functional. Treatment’s may include corrective orthotics, manual therapy to correct bio-mechanical dysfunctions and muscle imbalances, exercises to strengthen certain muscle groups and stretches to lengthen certain muscle groups.
If you have hip/low back pain or feel like you have a leg length discrepancy, contact a physiotherapist to determine the best possible treatment plan for you!