Leg length discrepancy (LLD) is a condition where the two lower limbs have a noticeable difference in length. Differences can range from minor to significant, impacting daily activities and posture. This article explores how healthcare professionals identify, assess, and implement various methods to address and correct leg length discrepancies.
Diagnosing Leg Length Discrepancy
Accurately identifying and measuring leg length discrepancy is a foundational step before any correction method can be considered. Healthcare providers typically begin with a physical examination, observing the patient’s gait and posture for signs of imbalance or compensatory movements like limping or walking on the toes of the shorter leg. The doctor may also use specific techniques, such as placing blocks of varying heights under the shorter leg until the pelvis appears level, to estimate the discrepancy.
For more precise measurement, imaging studies are often employed. X-rays, especially scanograms, are common tools used to obtain accurate bone length measurements of the femur (thighbone) and tibia (shinbone). A scanogram provides a full-length image of the legs while the patient is standing, for detailed skeletal assessment. In some cases, computerized tomography (CT) scans may also be used to gather detailed images of the bones and surrounding soft tissues for a comprehensive evaluation.
These diagnostic methods help determine whether the discrepancy is structural, meaning an actual difference in bone length, or functional, which occurs when bone lengths are equal but other conditions like pelvic tilt create the appearance of unequal length. Accurate measurement is crucial for determining the appropriate course of action. For instance, a difference greater than 2 centimeters is often considered significant enough to warrant intervention.
Non-Surgical Correction Methods
For smaller leg length discrepancies, non-surgical approaches are often the first line of management. Shoe lifts or orthotics, which are inserts placed inside or attached to the outside of the shoe on the shorter leg, are common non-invasive methods. These lifts physically add height to the shorter limb, effectively equalizing the leg lengths and improving gait and posture. Shoe lifts are particularly suitable for discrepancies of less than 2 centimeters, as larger lifts can become cumbersome or affect stability.
Physical therapy may also be recommended to address secondary issues that arise from a leg length difference, such as muscle imbalances or gait abnormalities. Therapists can guide patients through exercises designed to strengthen specific muscle groups, improve flexibility, and refine walking patterns. While physical therapy does not directly alter bone length, it plays an important role in enhancing overall function and reducing potential discomfort or pain associated with the discrepancy.
Surgical Correction Methods
When leg length discrepancies are more significant, typically exceeding 2 to 5 centimeters, surgical interventions may be considered to achieve more substantial correction. These procedures aim to either shorten the longer leg or lengthen the shorter leg. The choice of surgical method depends on factors such as the patient’s age, the magnitude of the discrepancy, and the specific bones involved.
One surgical approach for growing children is growth modulation, specifically epiphysiodesis. This procedure involves slowing or stopping the growth of the longer leg at its growth plates, which are areas of developing cartilage near the ends of long bones. By strategically targeting one or more growth plates, surgeons can allow the shorter leg to catch up as the child continues to grow, ultimately equalizing leg lengths by the time the child reaches skeletal maturity. This method does not require cutting the bone and allows the child to bear weight relatively quickly.
For more significant discrepancies or in patients who have finished growing, leg lengthening, also known as distraction osteogenesis, is a common procedure. This process involves surgically cutting the shorter leg’s bone, a procedure called an osteotomy. An external fixator, a frame attached to the bone with pins or wires, or an internal lengthening nail, such as a PRECICE nail, is then used to gradually pull the two bone segments apart. This slow, controlled separation stimulates the body to generate new bone in the gap, a process known as bone regeneration, effectively lengthening the limb over several months.
Alternatively, leg shortening surgery can be performed on the longer leg, typically for discrepancies between 2 and 6 centimeters in adults who have completed growth. This procedure involves removing a segment of bone from the middle of the longer leg, and then the remaining bone ends are reconnected using metal plates, screws, or an internal rod. While less common than lengthening procedures for very large discrepancies, shortening can be a suitable option to achieve equalization, though it may result in a slightly shorter overall adult height.
Post-Treatment Considerations
Following any correction method, whether surgical or non-surgical, post-treatment care is important for successful outcomes and regaining function. For non-surgical interventions like shoe lifts, regular monitoring ensures the lift remains effective and comfortable, addressing any new compensatory patterns that might emerge. Patients may need periodic adjustments to their orthotics as their body adapts or if the discrepancy changes over time.
After surgical correction, rehabilitation is comprehensive and often involves a dedicated physical therapy program. This therapy helps patients regain strength, improve range of motion in affected joints, and relearn proper walking mechanics. For leg lengthening procedures, physical therapy is particularly intensive, as it supports the new bone growth and helps stretch surrounding muscles and tissues to accommodate the increased length.
Patients may initially require assistive devices, such as crutches or walkers, during the recovery period to aid mobility and reduce weight-bearing on the healing limb. The timeline for recovery varies significantly depending on the specific procedure and individual healing rates. For instance, the lengthening phase of distraction osteogenesis can take several months, followed by a consolidation phase where the new bone hardens, potentially extending recovery to a year or more. Regular follow-up appointments with the healthcare team are important to monitor progress, address any complications, and ensure the patient achieves the best possible functional outcome.