Knee pain is a common issue. While it often originates in the knee joint, discomfort can sometimes stem from other areas. This is known as referred pain, where discomfort is felt away from its source, complicating diagnosis. Understanding these connections is key to finding relief.
Understanding Hip Impingement
Hip impingement (femoroacetabular impingement or FAI) occurs when the hip joint’s ball (femoral head) and socket (acetabulum) make abnormal contact. This is caused by extra bone growth on one or both structures, creating an irregular shape that hinders smooth movement. The bones rub against each other during motion, potentially damaging the joint over time.
FAI has two main types: Cam and Pincer, or a combination. Cam impingement involves an abnormally shaped femoral head with a bump that prevents smooth rotation within the socket. Pincer impingement occurs when extra bone extends over the hip socket rim, pinching the labrum (a cartilage ring). These abnormalities are often present from birth or develop during childhood, with some individuals remaining asymptomatic for years.
The Link Between Hip Impingement and Knee Pain
Hip impingement can cause knee pain through biomechanical changes and referred pain. When hip motion is restricted, the body compensates by altering lower limb movement. Altered movement, like excessive hip adduction or internal rotation, changes forces transmitted to the knee, potentially straining its structures.
Compensatory movements can also cause muscle imbalances around the hip and pelvis. Weakness in gluteal muscles or tightness in hip flexors may develop as the body avoids impingement, further altering biomechanics that impact the knee. These imbalances can affect patellofemoral joint (kneecap and thigh bone) alignment and loading, a common source of anterior knee pain. Continuous abnormal stress on the knee due to these changes can cause pain, even if the primary issue is in the hip.
Pain from the hip joint can also be referred to the knee. The hip shares nerve pathways with the knee, especially via femoral and obturator nerves. This neurological connection means hip pain signals can be perceived in the knee, particularly the front. While groin pain is the most common hip symptom, pain can radiate to the front of the thigh and below the knee, sometimes without direct knee pathology.
Recognizing Symptoms of Hip Impingement
Recognizing hip impingement symptoms can be challenging, as pain may not always be localized to the hip. The most common symptom is groin pain, often a dull ache. Pain worsens with deep hip flexion activities like squatting, prolonged sitting, or getting in and out of a car.
Beyond groin pain, discomfort may occur in the outer hip, buttock, or lower back. Hip or groin stiffness limiting movement is also common. Some report clicking, popping, or catching sensations in the hip joint during movement. Anterior (front) knee pain can be a symptom of hip impingement, especially when no clear knee-related cause exists. Pain intensity varies and may worsen over time as the condition progresses.
Diagnosis and Management Approaches
Diagnosing hip impingement involves a thorough evaluation by a healthcare professional. This process begins with a detailed medical history and physical examination, assessing hip range of motion and identifying painful positions. Specific maneuvers, like the impingement test, can elicit characteristic pain patterns.
Imaging tests are important for confirming diagnosis and assessing joint damage. X-rays can reveal abnormal bone shapes of the femoral head and acetabulum. MRI scans provide detailed images of soft tissues like the labrum and articular cartilage, which can be damaged by impingement. Sometimes, a diagnostic anesthetic injection into the hip joint can confirm it as the pain source if symptoms are temporarily relieved.
Management approaches for hip impingement range from conservative methods to surgery. Conservative treatment includes physical therapy, focusing on improving hip mobility, strengthening surrounding muscles, and modifying activities to avoid pain. Pain management strategies, such as NSAIDs, may also be used. If conservative measures are insufficient, surgical intervention, typically hip arthroscopy, may be considered to reshape bones and repair damaged cartilage or labrum. Consulting a healthcare professional is important for accurate diagnosis and a personalized treatment plan.