Knee pain is a widespread ailment affecting people of all ages. It is often assumed that the cause of the pain lies directly in the knee joint. However, medical examinations repeatedly show that the hip plays a central role in the development of knee pain. Pain radiating between the hip and knee joints is not uncommon and can significantly complicate diagnosis.

This article takes a detailed look at the connection between knee pain, hip disorders, and the mechanisms of pain radiation. We examine the medical background, treatment options, and preventative measures.

The complex connection between knee and hip

Anatomical basics

The knee and hip joints are part of the lower extremities and work closely together to ensure the mobility and stability of the human body. Problems in the hip area can lead to biomechanical imbalances that negatively affect the knee.

1. Nerve pathways and pain radiation: The nerves that supply the hip overlap with those of the knee. Pain originating in the hip is therefore often "projected" and perceived in the knee.
2. Biomechanics: Misalignments or diseases of the hip alter the gait pattern and can increase the load on the knee joint, leading to overload or wear and tear.

Pain radiating: How hip problems manifest themselves

• Hip osteoarthritis: One of the most common causes of radiating pain into the knee. Typical symptoms include activity-related pain that is first felt in the knee.
• Hip impingement: Restricted hip mobility can strain the iliotibial band muscle and secondarily lead to knee pain.
• Damage to the lumbar spine: Pain perception in the spine, hip, and knee often overlaps due to the same nerve pathways.

The role of the iliotibial tract in pain transmission from the hip to the knee

The iliotibial band , a broad tendon sheet on the outside of the thigh, plays a central role in force transmission and stability of hip and knee joint movements. Through its connection to the hip muscles and the knee, it can be both the cause and the pathway for pain transmission.

Anatomical connections

The iliotibial tract originates as a thickening of the fascia lata at the iliac crest. It is connected to several important muscle groups:

• Musculus tensor fasciae latae (TFL): A hip flexor that tightens the tractus and provides stability during gait.
• Gluteus maximus muscle: Also supports the tension of the iliotibial tract.

At the knee, the tractus attaches to Gerdy's tubercle (lateral tibial condyle) and stabilizes the joint in extension and flexion.

Mechanisms of pain transmission

Pain radiating from the hip to the knee can be transmitted via the iliotibial tract through the following mechanisms:

1. Increased tension in the iliotibial tract:

• Causes such as hip misalignment, osteoarthritis or muscular imbalances can overstrain the tractus.
• Chronic tension transmits friction or pulling to its distal attachments at the knee joint, leading to pain in the area of ​​the lateral knee.

1. Inflammation of the iliotibial tract (IT band syndrome):

• Repetitive movements, such as running or climbing stairs, cause friction between the tractus and the lateral femur (via the lateral epicondyle).
• This is often mistakenly interpreted as an isolated knee problem, but often has a primary cause in hip mechanics.

1. Myofascial pain transmission:

• Trigger points in the muscles, especially of the tensor fasciae latae or gluteus maximus, can radiate along the iliotibial tract to the knee.

Causes and triggers in the hip area

Common triggers for iliotibial band overload, which can cause secondary knee pain, include:

• Hip dysplasia: Causes altered stress patterns of the lateral thigh structures.
• Hip impingement: Restrictions in hip mobility lead to compensatory overuse of the iliotibial band.
• Pelvic misalignment: Unbalanced tension in the tractus due to asymmetrical pelvic position.

Common conditions affecting the hip and knee

Osteoarthritis: When the hip affects the knee

Hip osteoarthritis (coxarthrosis) can lead to changes in gait and increased stress on the knee. Increased limping or adopting a protective posture puts excessive strain on the knee joint and accelerates the degenerative process.

Bursitis of the hip

Inflamed bursae (bursitis) in the hip often cause local pain that can radiate down to the knee. The similar symptoms can lead to misdiagnosis.

Herniated discs

A herniated disc in the lumbar spine can put pressure on the sciatic nerve and cause pain that radiates into both the hip and knee.

Knee pain is typical in hip dysplasia

Hip dysplasia is a congenital or early childhood acquired malformation of the hip joint in which the acetabulum (hip socket) does not adequately fit the femoral head. This faulty fit leads to instability of the hip joint, which can cause various mechanical and neurological problems in the long term, including knee pain.

Mechanisms that explain knee pain in hip dysplasia:

1. Biomechanical effects:

• An unstable hip disrupts the transfer of force during walking. The load is often shifted to the knee joint, which can lead to improper stress and knee pain.
• Compensatory changes in the leg axis often occur, leading to unequal stress on the medial or lateral knee joint.

1. Pain radiating to:

• The hip joint shares a common sensory innervation with the knee, particularly via the femoral and obturator nerves. This can cause pain originating in the hip area to be perceived as knee pain.

1. Gait pattern abnormalities:

• Patients with hip dysplasia tend to adapt their gait by adopting a protective posture or increasing pelvic movements. This exacerbates the strain on the knee region.

Diagnostic strategies: Finding the origin of the pain

Clinical examination

• Gait analysis: Abnormalities such as limping or shortened steps provide information about the stress on the hip and knee.
• Palpation: Pain when pressure is applied to certain areas helps to narrow down the focus.

Imaging procedures

• X-ray images: Ideal for detecting osteoarthritis or fractures.
• MRI: Provides detailed images of soft tissues and helps to diagnose bursitis or muscle injuries.
• Ultrasound: Particularly useful for visualizing swelling or effusions.

Therapeutic approaches: Multidisciplinary solutions

Conservative treatment

• Physiotherapy: The goal is to strengthen and stabilize the muscles in order to eliminate biomechanical imbalances.
• Pain therapy: NSAIDs (non-steroidal anti-inflammatory drugs) help to reduce acute inflammation.
• Orthopedic aids: Individually adapted shoe insoles or bandages relieve the affected joint.

Surgical procedures

In some cases, especially with advanced osteoarthritis or severe injuries, surgery is necessary:

• Hip replacement: Replacing the damaged hip joint reduces secondary knee pain.
• Arthroscopy: Minimally invasive procedures can correct changes in the hip joint.

Prevention: How to prevent knee pain with healthy hips

Regular exercise

A balanced training program that combines strength, flexibility and endurance protects both joints.

Ergonomics in everyday life

• Proper sitting posture: Avoid prolonged sitting in a bent-over position.
• Hip-friendly strain: Regularly changing your sitting and standing position.

Nutrition

A diet rich in calcium and vitamin D strengthens bones and joints.

Conclusion

Knee pain should always be considered holistically, as it often originates in the hip or other anatomical structures. Accurate diagnosis and collaboration among various specialists are crucial for successful treatment.

By increasing awareness of these connections, many patients can receive appropriate therapy earlier and avoid long-term complications.