Trendelenburg Gait: Gluteus Medius Weakness vs Hip Pathology
Movement Dysfunction · 6 min read · 2026-01-03
Introduction
The Trendelenburg sign is one of the most important gait observations in clinical practice. A positive test indicates failure of the hip abductor mechanism, but the underlying cause can range from simple muscle weakness to nerve injury to hip joint disease.
The Normal Mechanism
During single-leg stance, the gluteus medius and minimus on the stance side contract to keep the pelvis level. Without this contraction, the pelvis drops on the unsupported (swing) side.
Positive Trendelenburg Sign
When the patient stands on the affected leg, the pelvis drops on the opposite side. During gait, this produces the characteristic Trendelenburg gait — or, if the patient compensates by leaning their trunk toward the affected side, the compensated Trendelenburg (Duchenne) gait.
Causes
Gluteus medius weakness (neurogenic):
- Superior gluteal nerve injury (L4–S1) — surgical damage, traction injury
- L5 radiculopathy — gluteus medius is primarily L5-innervated
- Poliomyelitis (historical, still relevant globally)
Gluteus medius weakness (myopathic):
- Muscular dystrophy
- Prolonged immobilization and deconditioning
- Post-surgical weakness (hip arthroplasty — lateral approach)
Hip joint pathology:
- Osteoarthritis — pain inhibits gluteus medius activation
- Femoral neck fracture — mechanical disruption of the abductor lever arm
- Developmental dysplasia of the hip — altered biomechanics
- Avascular necrosis — pain and structural collapse
Mechanical:
- Coxa vara — reduced abductor lever arm
- Non-union of greater trochanter — disrupted muscle attachment
Differentiating the Cause
The key question is whether the Trendelenburg sign is caused by weakness (neural or muscular) or pain (articular):
- Painless Trendelenburg with isolated abductor weakness: Think nerve injury or myopathy. Check L5 function, look for foot drop.
- Painful Trendelenburg with antalgic gait: Think hip joint pathology. Examine range of motion, check for crepitus, imaging.
- Post-surgical Trendelenburg: Common after lateral hip approach. Usually recovers with rehabilitation.
Clinical Pearl
In a patient with a Trendelenburg gait, always examine the lumbar spine. If there is concurrent foot drop (tibialis anterior weakness) and the Trendelenburg sign, the unifying diagnosis is L5 radiculopathy — one nerve root explains both findings.
Summary
Trendelenburg sign = failure of hip abduction on stance. Isolate the cause: painless weakness points to neural/muscular pathology; painful weakness points to the hip joint. Always check L5 function to exclude radiculopathy as the unifying diagnosis.