Leg length discrepancy (LLD) is a condition where one leg is measurably shorter than the other. This difference can range from a few millimeters to several centimeters, impacting an individual’s posture and movement. While a minor difference might go unnoticed, a more significant discrepancy can lead to various physical challenges.
What is Leg Length Discrepancy?
Leg length discrepancy can be categorized into two primary types: structural and functional. A structural LLD indicates an actual difference in the bone lengths of the thigh (femur) or shin (tibia/fibula). Functional LLD, conversely, occurs when the bone lengths are equal, but other factors, such as muscle imbalances, pelvic tilt, or joint contractures, create an apparent difference in leg length. This article primarily focuses on structural LLD and its direct corrections.
LLD can stem from various causes, including conditions present at birth. These might involve underdeveloped bones or issues like hemihypertrophy, where one side of the body grows larger. Acquired LLD can develop later in life due to factors such as growth plate injuries during childhood, poorly healed bone fractures, or bone infections. Bone diseases can also cause LLD.
Diagnosing LLD begins with a physical examination, where a doctor observes gait and may use measured blocks under the shorter leg to level the pelvis. For precise measurements, imaging techniques like X-rays or scanograms are utilized. A scanogram is a specialized full-length X-ray of both legs that allows for accurate measurement of each bone segment, providing detailed information for treatment planning.
Non-Surgical Treatments
For smaller leg length discrepancies, non-surgical approaches are often used. Shoe lifts or orthotics are a common method to compensate for the length difference. These can be internal heel inserts for minor discrepancies or external sole lifts for larger differences, typically addressing discrepancies up to 2-3 centimeters. Properly fitted lifts can help normalize gait, reduce strain on joints, and alleviate associated pain.
Physical therapy addresses issues arising from LLD. Therapists work to improve muscle strength, flexibility, and range of motion. Exercises may focus on correcting gait abnormalities and strengthening core muscles to minimize compensatory movements and reduce discomfort in the back, hips, or knees.
For very small discrepancies, or for children who are still growing, observation may be recommended. Regular monitoring allows healthcare providers to track the discrepancy’s progression. This approach is considered when the LLD is not causing significant symptoms or is expected to improve naturally as a child matures.
Surgical Treatment Options
When non-surgical methods are insufficient or for larger discrepancies, surgery may be considered. One option for growing children is growth plate modulation, also known as epiphysiodesis. This procedure involves slowing or stopping the growth of the longer leg’s growth plate, allowing the shorter leg to catch up. It is a permanent solution, typically performed for predicted discrepancies between 2 and 6 centimeters.
Limb lengthening is a complex procedure used to increase the length of the shorter leg. Techniques include external fixation, such as the Ilizarov method, or internal lengthening nails. These methods rely on distraction osteogenesis, a process where new bone is gradually formed. The bone is surgically cut, and a device slowly pulls the two segments apart, stimulating new bone growth in the gap. This process requires significant patient commitment and can take several months.
Another surgical approach, limb shortening, involves removing a segment of bone from the longer leg. This procedure is performed on individuals who have reached skeletal maturity with moderate discrepancies. Unlike limb lengthening, limb shortening is a single-stage operation. The choice between lengthening and shortening depends on the magnitude of the discrepancy and the patient’s overall height.
Choosing the Right Treatment Plan
Selecting the most appropriate treatment plan for leg length discrepancy involves several factors. The magnitude of the discrepancy is a primary determinant, as smaller differences often respond well to non-surgical methods, while larger ones may necessitate surgical intervention. A patient’s age and remaining growth potential are also important, as growth plate modulation is only an option while bones are still growing.
The underlying cause of the LLD influences treatment choices. Associated conditions, such as angular deformities or joint issues, also influence decisions. A patient’s lifestyle, activity level, personal preferences, and understanding of benefits and risks are all weighed.
Treatment decisions for LLD are often made through a multidisciplinary approach. A team of specialists, including orthopedic surgeons, physical therapists, and orthotists, works together to develop a comprehensive plan. This ensures the chosen treatment is tailored to individual needs and goals, to improve function and quality of life.