A Trendelenburg gait is an abnormal walking pattern caused by the hip’s inability to stabilize the pelvis. The most visible sign is a pronounced dipping or dropping of the pelvis on one side as the person lifts the opposite leg during walking. This results in a noticeable side-to-side sway, which may appear as a limp or lurch. This gait is a physical sign of underlying weakness or dysfunction affecting the hip joint, muscles, or nerves.
The Gluteal Muscle Group and Nerve Function
A stable gait relies on the proper function of the hip abductor muscles, primarily the Gluteus Medius and Gluteus Minimus. These muscles maintain a level pelvis when the body’s weight shifts entirely onto one leg during the stance phase of walking. The abductor muscles on the standing leg contract powerfully to prevent the pelvis from tilting downward on the side of the lifted leg.
A Trendelenburg gait occurs when these muscles are too weak to counteract gravity and body weight, allowing the pelvis to drop toward the unsupported side. This deficit is identified clinically using the Trendelenburg Sign, where a person stands on one leg. A positive sign occurs if the pelvis drops on the side of the lifted leg, confirming the lack of stabilization from the abductors on the standing side. The Superior Gluteal Nerve supplies these muscles, and any interruption to its signal causes abductor weakness.
Causes Stemming from Hip Joint and Structural Issues
Many causes of this gait pattern originate from mechanical or structural problems local to the hip joint that interfere with the hip abductor muscles’ function. Severe osteoarthritis, a condition where the protective cartilage wears down, often causes a Trendelenburg gait. Chronic pain from the degenerated joint can inhibit muscle contraction, or structural changes may alter the mechanics, reducing the abductors’ leverage.
Hip fractures, particularly those involving the femoral neck or the greater trochanter, can severely compromise the hip’s mechanical integrity. The greater trochanter is the bony attachment point for the Gluteus Medius and Minimus. A fracture here can detach these muscles, causing immediate weakness. Even after healing, if muscle attachments are not fully restored, a persistent stabilization deficit can result.
Complications following total hip replacement surgery are a frequently encountered cause, often resulting from the surgical approach. During certain procedures, the hip abductor muscles or tendons must be cut or detached for surgeon access. If they are not repaired or reattached correctly, permanent weakness can result. Congenital conditions like Developmental Dysplasia of the Hip (DDH), where the hip socket is shallow and unstable, also lead to this gait. This structural abnormality compromises the abductor muscles’ biomechanical lever arm, preventing them from generating the necessary stabilizing force.
Causes Stemming from Nerve Damage and Neuromuscular Disorders
Causes related to nerve damage involve the failure of the nervous system to communicate with the hip abductor muscles. Direct injury to the Superior Gluteal Nerve is a localized cause resulting in immediate paralysis or paresis of the Gluteus Medius and Minimus. This nerve can be damaged by trauma, such as a pelvic fracture, or inadvertently severed or compressed during surgery around the hip or pelvis.
A recognized cause of localized nerve damage is iatrogenic injury, often from deep intramuscular injections administered incorrectly into the upper outer quadrant of the buttock. Such an injection can pierce and damage the nerve, disrupting the electrical signals that tell the hip abductors to contract. Nerve root compression in the lower spine, specifically affecting the L4 or L5 nerve roots that contribute to the superior gluteal nerve, can also mimic this localized weakness.
Systemic conditions and central neurological events represent broader causes of abductor dysfunction. A stroke, for instance, can cause hemiplegia (paralysis on one side of the body), resulting in a failure of motor control to the gluteal muscles and a Trendelenburg gait on the affected side. Certain neuromuscular diseases, such as poliomyelitis (a viral disease attacking motor neurons) or types of muscular dystrophy (causing progressive muscle wasting), can lead to bilateral hip abductor weakness. These diseases cause a more generalized weakness that often results in a “waddling” gait, which is a form of Trendelenburg gait affecting both sides of the body alternately.