Patients with lower back pain often secondary to irritation of the L5 and S1 nerve roots will have difficulty not only due to the pain but due to weakness of the hip abductor muscles.
The most powerful hip abductor is the gluteus medius. It is supplied by the superior gluteal nerve (L4, L5 and S1). The L5 nerve root has the strongest representation in this muscle. The other hip abductors are the other muscles are tensor fascia latae and gluteus minimus which are also supplied by the superior gluteal nerve.
Hip abduction can be tested with the patient supine with the thighs spread apart. The examiner then pushes the thigh inward to the midline. The hip abductors can also be tested with the patient lying on his side with the tested side uppermost. The patient then lifts the thigh up against gravity. The most functional way of testing for hip abduction is to have the patient stand on one limb. If he is standing on his right leg and if he has weakness in his right hip abductor muscles his opposite hip will drop. This testing is called the Trendelenburg testing. To prevent the left hip from dropping in the case of a right hip abductor weakness, the patient may lean over to the right. This is also an indicator of weakness of the hip abductors on the right side..