From the Guidelines
A positive hip abduction test, also known as the Trendelenburg test, is significant as it may indicate a tear or avulsion of the gluteus medius tendon, particularly in patients with a history of total hip arthroplasty. This is based on a recent study published in the Journal of the American College of Radiology in 2023 1. The study found that ultrasound (US) can identify tendinopathy, partial tear, and complete tears/avulsion of the gluteus medius tendon in nonsurgical and postsurgical patients. Furthermore, the study noted that patients with positive Trendelenburg signs were more likely to have abductor tendon tears, with half of the patients with positive signs having tears, compared to only 3 of 26 patients with negative Trendelenburg tests.
Some key points to consider when interpreting the results of the Trendelenburg test include:
- The postsurgical appearance of repaired gluteal tendons can vary depending on the type of procedure performed, but continuity of the reattached tendon should be present and can be demonstrated on US 1.
- The presence of a positive Trendelenburg sign does not necessarily mean that surgical revision is required, as the study did not provide a comparison to surgical revision.
- Ultrasound is a useful diagnostic tool for evaluating the abductor tendons after total hip arthroplasty, particularly in patients with positive Trendelenburg signs.
In clinical practice, a positive hip abduction test should prompt further evaluation, including ultrasound imaging, to assess for potential gluteus medius tendon tears or other abnormalities. This is particularly important in patients with a history of total hip arthroplasty, as timely diagnosis and treatment can help improve outcomes and reduce the risk of complications.
From the Research
Significance of a Positive Hip Abduction Test
The hip abduction test, also known as the Trendelenburg test, is used to assess the strength and function of the hip abductor muscles. A positive test result indicates weakness or dysfunction of these muscles.
Key Findings
- The hip abductors are the most important muscles around the hip joint, and their strength is essential for maintaining proper hip function 2.
- Studies have shown that hip abductor strength is reduced in individuals with hip osteoarthritis compared to healthy controls 3.
- Women with chronic hip joint pain have been found to have decreased hip abductor strength compared to asymptomatic controls, despite having larger gluteal muscle volume 4.
- The side-lying position has been shown to be the most valid and reliable position for assessing unilateral hip abductor strength 2.
- The Hip Stability Isometric Test (HipSIT) has been developed as a new method to assess hip posterolateral muscle strength, and has been shown to have excellent intrarater and interrater reliability 5.
Clinical Implications
- A positive hip abduction test result may indicate hip abductor muscle weakness or dysfunction, which can contribute to hip joint pain and dysfunction.
- Strengthening the hip abductor muscles may be an effective rehabilitation strategy for individuals with hip osteoarthritis or chronic hip joint pain.
- The use of reliable and valid assessment methods, such as the HipSIT, can help clinicians to accurately diagnose and monitor hip abductor muscle strength and function.