Compressive load

Many people experience aching around the greater trochanter, the bony prominence on the outside of the thighbone, and find lying on their side more uncomfortable. In the past, discomfort in this area was mainly explained as inflammation of the small fluid-filled sac (bursa) overlying it. Today, changes in the tendons where the gluteus medius and gluteus minimus attach to the bone—known as Gluteal tendinopathy—are widely described as the main underlying issue. Compressive load is considered a key mechanism behind these tendon changes. Greater trochanteric pain syndrome is another related term.

The Iliotibial band, which runs along the outside of the hip and thigh, covers the greater trochanter. When the leg moves into Adduction, meaning toward the body's midline, this band becomes taut and wraps more firmly around the greater trochanter. This compresses the Gluteus medius and Gluteus minimus tendons between the band and the bone.

A cadaveric biomechanical study estimated that the compressive force increased from about 4N with the hip in neutral to about 36N at 10 degrees of adduction and about 106N at 40 degrees of adduction (Birnbaum et al., 2004). This means that even a small inward movement of the leg can make a substantial difference to how much the tendons are compressed.

• Sitting with your legs crossed — The knee of the upper leg crosses over to the opposite side, bringing the hip into adduction.
• Standing for a long time with your weight shifted onto one leg — One side of the pelvis shifts outward, and the opposite leg tilts inward.
• Sleeping on your side — The upper leg drops downward, bringing the knee toward the bed and the hip into adduction. The hip underneath may be more uncomfortable because it bears body weight directly.
• Going up or down stairs and walking — If the pelvis drops to the side while you are supported on one leg, the knee moves inward.
• Sitting with your legs together — Similar positions include sitting on a chair with both knees pressed together or tucking one leg beneath the other.

In a large clinical trial conducted in Australia in 2018 (the LEAP trial), people with gluteal tendinopathy who received education together with progressive exercise showed greater improvement at 8 weeks than those who received a steroid injection or followed a wait-and-see approach. This pattern continued at 52 weeks. The education in this trial included recognizing and avoiding positions that increase compression.

Here are some approaches to try in daily life.

• Keep both feet side by side on the floor without crossing your legs. Sitting with your knees about hip-width apart can feel comfortable.
• Distribute your weight evenly between both legs when standing. If you spend a long time leaning onto one side, alternate sides to give each a rest.
• Place a Knee pillow between your knees when sleeping on your side. This keeps the upper leg from dropping down and holds it in line with the pelvis, reducing the angle of hip adduction. You can also lie with the painful side facing away from the bed.
• Keep your knees from moving inward on stairs and when walking. Try walking slowly while thinking about keeping your knees pointing in the same direction as your toes.
• Increase exercise gradually. Gradually increasing the load, rather than raising it substantially all at once, is thought to be easier on the tendons. See Load management.

The similar names can be confusing, but compressive load here refers to compression between tissues created by joint positioning. It is a different concept from the external pressure applied by Compression stockings worn on the legs or Compression garments.

If pain on the outside of your hip persists enough to keep waking you at night, does not improve after several weeks, is accompanied by numbness or tingling extending down the leg, or begins after a fall or impact, it is a good idea to have the cause assessed. Problems in the lower back or hip joint can also cause similar pain.