Iliopsoas Tendinitis after Hip Replacement

What is the Iliopsoas?

The iliopsoas is a powerful muscle group located deep within the abdomen, comprised of two muscles: the iliacus and the psoas major. These muscles originate from different areas—the iliacus from the iliac fossa of the pelvis and the psoas major from the lumbar spine. They converge to form the iliopsoas tendon, which attaches to the lesser trochanter of the femur. The primary function of the iliopsoas is hip flexion, bringing the thigh towards the abdomen, and it also plays a role in stabilizing the pelvis and lumbar spine during movements like walking, running, and climbing stairs. The iliopsoas is integral to various daily activities and sports, making it essential for overall mobility and function.

What is Iliopsoas tendonitis after total hip arthroplasty (THA)?

Iliopsoas tendinitis after total hip arthroplasty (THA) is a condition characterized by inflammation or irritation of the iliopsoas tendon, which can occur due to altered hip biomechanics, impingement, or component malpositioning following hip replacement surgery.

What is the cause?

The iliopsoas tendon is a primary hip flexor, composed of the iliacus and psoas major muscles, which inserts onto the lesser trochanter of the femur. Following THA, alterations in hip anatomy, biomechanics, and soft tissue tension can predispose patients to iliopsoas tendonitis. Common causes include impingement of the iliopsoas tendon against the acetabular component or anterior aspect of the femoral prosthesis, excessive tension or stretching of the iliopsoas tendon during surgery, malpositioning of the components leading to altered hip biomechanics, or component wear resulting in synovitis and irritation of the surrounding soft tissues.

What are the risk factors?

Several factors may increase the risk of developing iliopsoas tendonitis following THA. These include pre-existing iliopsoas pathology, such as tendinopathy or impingement, anatomical variations in iliopsoas tendon course or insertion, surgical approach (e.g., anterior approach THA), component malpositioning, leg length discrepancy, excessive anteversion of the acetabular component, and patient-related factors such as obesity, hip flexor weakness, or abnormal gait patterns.

What are the symptoms?

Patients with iliopsoas tendonitis following THA typically present with groin pain, anterior hip pain, or snapping sensations in the hip joint. Pain may be exacerbated by activities that require hip flexion, such as rising from a seated position, walking uphill, or performing activities of daily living. Snapping or clicking sensations may occur with hip movement and may be accompanied by a visible or palpable snap as the iliopsoas tendon moves over the prosthetic components. Physical examination may reveal tenderness over the anterior hip, pain with resisted hip flexion, and reproduction of symptoms with provocative maneuvers such as the Thomas test or iliopsoas stretch test.

How is it Diagnosed?

Diagnosing iliopsoas tendonitis after THA requires a thorough clinical evaluation, including a detailed history, physical examination, and appropriate imaging studies. Radiographic evaluation with X-rays may assess for component malpositioning, leg length discrepancy, or signs of component wear. Magnetic resonance imaging (MRI) or ultrasound may be used to visualize the iliopsoas tendon and assess for signs of inflammation, tendinopathy, or impingement. Dynamic imaging modalities such as dynamic ultrasound or magnetic resonance arthrography may be helpful in demonstrating abnormal iliopsoas tendon movement or impingement during hip flexion.