Leg length discrepancy (LLD) is a condition where a person’s two legs have a measurable difference in length. This difference can range from a minor variation that causes no symptoms to a significant inequality affecting posture and gait mechanics. A true LLD involves an actual difference in bone length, often caused by congenital issues, developmental factors, or trauma. Untreated, larger discrepancies can contribute to long-term issues such as lower back pain, hip problems, and an inefficient walking pattern.
Initial Assessment and Referral
The first medical professional most people consult regarding suspected LLD is their Primary Care Physician (PCP) or Pediatrician. These practitioners serve as the initial screening point and gatekeeper for specialized care. During this first visit, the doctor will look for visible signs such as an obvious limp, uneven shoulder height, or a tilt in the pelvis while standing.
The PCP performs preliminary measurements using clinical methods to estimate the difference. A common technique is the tape measure method, stretching a tape from the anterior superior iliac spine (ASIS) to the medial malleolus. The block test, which involves placing measured blocks under the shorter leg until the pelvis is level, is considered the most reliable clinical screening method. If these initial assessments suggest a genuine, structural discrepancy, a referral to a specialist is then made.
The Orthopedic Specialist: Diagnosis and Treatment Planning
The definitive diagnosis and treatment plan for LLD fall under the expertise of an Orthopedic Specialist, particularly those experienced in limb deformity. This specialist obtains highly precise measurements of the discrepancy, moving beyond preliminary clinical estimation. Accurate measurement is achieved through specialized radiographic imaging, such as a full-length standing anteroposterior radiograph, often called a Scanogram.
A Computed Tomography (CT) Scanogram is frequently used, providing accurate bone length measurements with less radiation exposure than conventional methods. The Orthopedist uses these images to measure the length of the femur and tibia, identifying which bone segment contributes to the inequality. They also determine if the LLD is static (non-progressing) or progressive, which is important for growing patients.
Based on the precise measurement and the patient’s skeletal maturity, the Orthopedic Specialist crafts a comprehensive treatment strategy. Discrepancies less than two centimeters are typically managed non-surgically, while larger differences often require surgical consideration. The specialist’s decision dictates whether the patient is directed toward physical therapy and orthotics or advanced surgical correction. For children, the doctor uses predictive algorithms and growth charts to calculate the final expected discrepancy at skeletal maturity, allowing for precise timing of any necessary surgical intervention.
Allied Health Professionals for Non-Surgical Management
For mild to moderate LLD that does not require surgery, a team of allied health professionals implements the non-surgical plan dictated by the Orthopedist. Physical Therapists (PTs) play a significant role in addressing the secondary effects of the discrepancy on the body. They focus on improving gait mechanics, correcting compensatory postures, and strengthening muscles that have become imbalanced due to the difference in limb length.
Orthotists and Podiatrists are the specialists responsible for the direct equalization of leg lengths using external devices. They design and fit custom-made shoe inserts, heel lifts, or external sole modifications. For a discrepancy of up to two centimeters, a simple lift placed inside the shoe is often sufficient to restore balance and reduce strain on the joints. For larger non-surgical corrections, an external lift built into the sole of the shoe may be necessary.
When Advanced Surgical Correction is Necessary
When the leg length difference is significant, generally exceeding two centimeters, or when non-surgical options have failed, a specialized Orthopedic Surgeon will manage the case. These surgeons often specialize in limb lengthening and complex reconstruction procedures. Surgical goals are to either shorten the longer leg or lengthen the shorter leg to achieve near-equal limb length.
For skeletally immature patients, a procedure called epiphysiodesis may be performed to slow the growth of the longer limb by manipulating the growth plate. This allows the shorter leg to catch up over time, and the timing of this procedure is important to prevent over- or under-correction. For both children and adults with larger discrepancies, the shorter leg can be lengthened through a process called distraction osteogenesis. This involves cutting the bone and using an external fixator or an internal intramedullary nail to gradually pull the bone segments apart, stimulating new bone growth.