Leg-Length Discrepancy (LLD)
Leg-Length Discrepancy (LLD)
Key Points
- Defined as inequality between the lengths of lower limbs
- Can be congenital or acquired
- Classified as structural (anatomic) or functional
- Clinical significance varies with magnitude of discrepancy
- Treatment approach depends on current discrepancy and predicted discrepancy at maturity
Overview
Leg-length discrepancy is a condition where one lower limb is shorter than the other, measured from the hip to the ground. The difference can range from a few millimeters to several centimeters, with varying clinical significance based on the magnitude.
Etiology
Congenital Causes:
- Proximal Focal Femoral Deficiency (PFFD)
- Fibular Hemimelia
- Tibial Hemimelia
- Developmental Dysplasia of Hip (DDH)
- Hemihypertrophy syndromes:
- Beckwith-Wiedemann Syndrome
- Klippel-Trenaunay-Weber Syndrome
- Neurofibromatosis
Acquired Causes:
- Trauma:
- Physeal injuries
- Fractures with malunion
- Growth plate arrests
- Infection:
- Osteomyelitis
- Septic arthritis
- Tumors and tumor-like conditions
- Paralytic disorders
- Radiation therapy
Clinical Presentation
History:
- Age of onset
- Rate of progression
- Associated symptoms:
- Back pain
- Hip pain
- Knee pain
- Gait abnormalities
- Family history
- Developmental history
Physical Examination:
- Standing Assessment:
- Pelvic obliquity
- Compensatory scoliosis
- Standing alignment
- Gait Assessment:
- Trendelenburg gait
- Compensatory mechanisms
- Measurement Techniques:
- Direct measurement
- Block test
- Indirect measurement
Diagnosis & Assessment
Imaging Studies:
- Standing AP radiographs of lower extremities
- Scanogram:
- Three separate exposures of hips, knees, and ankles
- Allows precise measurement
- CT scanogram:
- More accurate than conventional scanogram
- Lower radiation exposure
- MRI:
- Useful for soft tissue abnormalities
- Growth plate assessment
Growth Prediction:
- Moseley Straight Line Graph
- Anderson and Green Growth Remaining Charts
- Multiplier Method
Management
Treatment Guidelines:
- < 2 cm: Observation or shoe lift
- 2-5 cm: Consider epiphysiodesis
- > 5 cm: Limb lengthening procedures
Non-operative Treatment:
- Shoe lifts:
- Internal lift up to 1.5 cm
- External lift for larger discrepancies
- Physical therapy
- Regular monitoring
Operative Treatment:
- Epiphysiodesis:
- Permanent growth arrest
- Timing crucial
- Techniques: percutaneous, permanent
- Limb Lengthening:
- External fixation methods
- Internal lengthening nails
- Gradual correction
Complications & Long-term Outcomes
Untreated LLD Complications:
- Chronic back pain
- Degenerative joint disease
- Gait abnormalities
- Functional scoliosis
- Hip and knee osteoarthritis
Treatment Complications:
- Epiphysiodesis:
- Over/under correction
- Angular deformity
- Limb Lengthening:
- Pin tract infection
- Joint contractures
- Muscle weakness
- Nerve injury
- Delayed consolidation
