The act of crossing one leg over the opposite knee, commonly known as the figure-four position, is a familiar posture. When this movement causes a sharp, deep ache in the hip or buttock, it often signals excessive strain on underlying soft tissue structures. This pain is typically not a joint problem in the hip socket itself, but rather mechanical irritation to the muscles, tendons, or nerves traveling through the posterior hip and gluteal region. Understanding the biomechanics of this position helps clarify why this posture triggers discomfort.
The Biomechanics of Crossing Your Legs
The figure-four position places the hip in a combination of flexion, abduction, and external rotation. This movement is designed to stretch the posterior hip capsule and the deep external rotator muscles. The primary muscle group targeted is the deep hip rotators, including the piriformis, obturator internus, and the gemelli muscles, which connect the pelvis to the femur. When the leg is crossed, the deep rotation applies tension to these structures, pulling them tautly across the bony pelvis. If these muscles or tendons are already tight, inflamed, or irritated, this movement causes immediate pain due to the direct mechanical stress.
Primary Causes of Pain During Figure-Four Positioning
Piriformis Syndrome
The most recognized cause of pain during this stretch is Piriformis Syndrome, involving irritation of the piriformis muscle. The piriformis is a small, flat muscle located deep within the buttock, running from the sacrum to the femur. The sciatic nerve, the body’s largest nerve, typically passes directly beneath this muscle. In Piriformis Syndrome, the muscle can become tight or go into spasm, compressing or irritating the sciatic nerve. Because the figure-four position forces the piriformis into a lengthened, stressed state, this action significantly increases pressure on the nerve or strains the muscle. The result is a deep, aching pain in the buttock that can radiate down the back of the leg, mimicking sciatica.
Gluteal Tendinopathy
Another common source of this pain is Gluteal Tendinopathy, often part of Greater Trochanteric Pain Syndrome (GTPS). This condition involves the deep gluteal tendons, specifically the Gluteus medius and Gluteus minimus, which attach to the side of the hip at the greater trochanter. Gluteal tendinopathy is characterized by changes in the tendon structure, often due to repetitive strain or excessive compression. The figure-four position, especially when sitting and leaning forward, can aggravate this condition in two ways. First, the external rotation stretches the already painful tendons. Second, prolonged crossing of the legs can compress the gluteal tendons against the greater trochanter. This pain is typically felt on the outside of the hip and may extend down the lateral thigh.
Sacroiliac (SI) Joint Dysfunction
Pain during the figure-four movement may also be referred from the Sacroiliac (SI) joint, which connects the sacrum to the ilium on either side of the pelvis. The SI joint transfers forces between the upper body and the legs. The asymmetrical posture of crossing one leg over the other places a twisting force on the joint and its strong ligamentous supports. If the SI joint is either hypermobile (too loose) or hypomobile (too stiff), the uneven stress of the figure-four position can cause the joint to move improperly or become temporarily overloaded. This results in a sharp or dull ache localized to the joint itself, often felt just to the side of the lower spine or radiating into the buttock.
Immediate Steps for Symptom Relief
When hip pain flares up from crossing your leg, immediately change the aggravating position by uncrossing the leg and sitting with both feet flat on the floor. Avoid prolonged sitting and stand up and walk around for a few minutes every half hour to prevent stiffness. Activity modification is necessary, meaning you must avoid:
- The specific figure-four position.
- Standing with weight on one leg.
- Sleeping directly on the affected hip.
- Any movement that causes sharp, immediate pain.
Applying ice to the painful area, typically the deep buttock or outer hip, for 15 to 20 minutes can help reduce localized irritation and nerve sensitivity. Gentle movement can help maintain mobility without causing further strain, such as performing a gentle pelvic tilt or simple knee-to-chest lifts only to the point of a mild, non-painful stretch. Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, may be used temporarily to manage pain and reduce local inflammation, but consult a physician before starting any medication regimen.
Professional Diagnosis and Long-Term Treatment
If hip pain is intense, prevents you from bearing weight, or is accompanied by systemic symptoms like fever or sudden swelling, seek immediate medical attention. For persistent pain lasting more than a few days, a professional diagnosis is necessary. A physician will begin with a thorough physical examination, testing for pain provocation in the piriformis, gluteal tendons, and SI joint. Diagnostic imaging, such as X-rays, can rule out structural bone issues, while an MRI may visualize soft tissues to assess for tendinopathy or nerve entrapment. Long-term treatment centers on Physical Therapy, focusing on correcting biomechanical issues. Treatment includes targeted strengthening of the core and hip abductor muscles (Gluteus medius and minimus) to stabilize the pelvis and reduce strain on the deep rotators. For persistent, localized inflammation, a physician may recommend a corticosteroid injection into the affected tendon or muscle to provide pain relief and facilitate physical therapy participation.