What is the cause of my femur (thigh bone) length discrepancy?

From the Guidelines

Femur length discrepancies can occur due to several reasons, including congenital conditions, growth plate injuries, infections, fractures that heal improperly, or diseases affecting bone growth, and the most recent evidence suggests that determining the cause requires a comprehensive evaluation by an orthopedic specialist 1. The cause of femur length discrepancy can be complex and multifactorial. Some possible causes include:

• Congenital conditions, such as skeletal dysplasia, which can affect bone growth and development 1
• Growth plate injuries, which can damage the growth plates and affect bone growth 1
• Infections, such as osteomyelitis, which can affect bone development and growth 1
• Fractures that heal improperly, which can lead to discrepancies in bone length
• Diseases affecting bone growth, such as juvenile arthritis or Legg-Calvé-Perthes disease To determine the best approach, it is essential to consult with an orthopedic specialist who can evaluate the specific situation through physical examination and imaging studies like X-rays or CT scans to measure the exact difference and recommend appropriate treatment 1. Some key points to consider in the evaluation and management of femur length discrepancies include:
• The severity of the discrepancy, which can range from minor differences (less than 2 cm) to significant discrepancies that may require surgical intervention
• The impact of the discrepancy on daily life and mobility, which can inform treatment decisions
• The potential for metabolic complications, such as diabetes or cardiovascular disease, which may be associated with certain skeletal dysplasias 1
• The importance of maintaining a healthy lifestyle and weight, which can help prevent metabolic complications and improve overall health outcomes 1

From the Research

Possible Causes of Femur Length Discrepancy

• Leg length inequality can occur after childhood femoral fractures, with significant overgrowth happening in the first two years after injury 2
• Developmental dysplasia of the hip can cause leg-length discrepancy due to complications such as avascular necrosis, femoral shortening, and varus at reduction 3
• Congenital short femur can lead to knee arthritis after Wagner lengthening, with factors such as knee instability and temporary subluxation during the lengthening procedure contributing to the development of arthritis 4
• Loss of femoral antecurvatum after elastic stable intramedullary nailing of diaphyseal fractures of the femur in children can result in limb length discrepancy 5
• Femoral morphology asymmetry in hip dysplasia can make radiological leg length measurement inaccurate, with significant asymmetry in femoral length between the greater and lesser trochanter and the knee 6

Factors Contributing to Femur Length Discrepancy

• Age at trauma, with overgrowth significantly depending on the age at trauma (4-9 years) 2
• Number of repositions, with 2 or more repositions leading to overgrowth 2
• Degree of axial deviation, with > 10 degrees leading to overgrowth 2
• Delayed surgical treatment, with > 48 hours leading to overgrowth 2
• Type of surgical treatment, with plate fixation inducing overgrowth 2
• Knee instability and temporary subluxation during the lengthening procedure, contributing to the development of arthritis 4