Normal: When the body weight is supported on one limb, the abductors (gluteus medius and minimus) of the supported side contract and raise the opposite unsupported side of the pelvis.
Abnormal: If the abductor mechanism is defective, the unsupported side of pelvis drops and this is known as positive trendelenburg’s test.
Use: To assess the integrity of abductor mechanism of hip
Causes of positive trendelenburg sign or test:
This test is positive in conditions in which any of the three – fulcrum (femoral head), lever arm (femoral neck length) or power (muscles/nerves) are affected.
Note: The primary abductors of hip are gluteus medius and minimus while tensor fascia lata and sartorius are accessory abductors of hip.
1. Power paralysis of abductor muscles:
- Superior gluteal nerve palsy
- Iliotibial tract palsy
2. Decreased lever arm:
- Fracture neck of femur
3. Absence of stable fulcrum:
- Dislocation of hip
- Destruction of femoral head: Perthe’s disease, Avascular necrosis of head of femur, Late stages of TB hip, Septic arthritis