Snapping Hip Syndrome (coxa saltans) is characterized by a distinct snapping or clicking sensation around the hip joint. This sensation is often palpable and can sometimes be accompanied by an audible sound. While frequently painless, the condition can occasionally lead to discomfort or pain, especially with repeated movements. The snapping typically occurs as muscles or tendons glide over bony structures, or due to issues within the joint itself.
Understanding the Types of Snapping Hip
The snapping sensation can originate from different areas, leading to three primary types. External snapping hip occurs on the outer side, typically when a thick band of tissue or tendon glides over a bony protrusion. Internal snapping hip is felt at the front, usually involving tendons that cross the joint. Intra-articular snapping hip arises from issues deep within the hip joint itself, often involving structures inside the joint capsule.
Causes of External Snapping Hip
External snapping hip originates from the movement of specific tendons or fibrous bands over the greater trochanter, a bony prominence on the upper outer portion of the femur. The primary structures involved are the iliotibial (IT) band and occasionally the posterior fibers of the gluteus maximus tendon. As the hip moves, these structures can become taut and momentarily catch on the greater trochanter, then rapidly release. This sudden release generates the palpable or audible snapping sensation on the side of the hip.
Increased tension or thickening within the iliotibial band is a frequent contributor. When the IT band is less pliable, its smooth gliding over the greater trochanter is impeded, leading to friction and the characteristic snap. An overly tight gluteus maximus tendon can also produce this effect.
Causes of Internal Snapping Hip
Internal snapping hip manifests as a sensation at the front of the hip and is most commonly associated with the iliopsoas tendon. This tendon crosses the front of the hip joint. As the hip moves, the iliopsoas tendon can snap over bony prominences such as the iliopectineal eminence or the anterior aspect of the femoral head. This mechanical interaction creates the distinctive internal snapping sound or feeling.
Inflammation or thickening of the iliopsoas tendon, known as iliopsoas tendinitis, can heighten the likelihood of this snapping. When the tendon is irritated, its smooth gliding motion is compromised, causing it to catch more easily on underlying bone. Less commonly, the iliofemoral ligaments, strong fibrous bands that stabilize the front of the hip joint, can also contribute. These ligaments may become taut and snap during certain hip movements, particularly those involving extension and external rotation, producing a similar sensation.
Causes of Intra-Articular Snapping Hip
Intra-articular snapping hip originates from within the hip joint capsule. One frequent cause is a labral tear, which involves damage to the labrum. The labrum is a ring of cartilage that rims the hip socket, deepening it and providing stability. A tear in this cartilage can create a flap that catches during hip movement, resulting in a deep clicking, catching, or snapping sensation.
Another cause is the presence of loose bodies within the joint. These are small fragments of bone or cartilage floating freely in the synovial fluid. As the hip moves, these loose bodies can get caught between the joint surfaces, leading to a mechanical snapping or locking sensation. Damage to the articular cartilage, the smooth tissue covering the ends of the bones, can also contribute. Irregularities in this cartilage surface can cause friction and aberrant movement, leading to symptoms.
Factors Increasing Risk
Several factors can increase susceptibility to Snapping Hip Syndrome. Participation in activities involving repetitive hip flexion and extension is a significant risk factor. Athletes like dancers, gymnasts, runners, and soccer players frequently engage in these movements, leading to overuse and irritation of hip tendons and structures. This constant friction can predispose them to the condition.
Muscle imbalances around the hip and pelvis also contribute to increased risk. Tight hip flexors or weak gluteal muscles can alter normal hip mechanics, placing stress on tendons and increasing their likelihood of snapping. Anatomical variations in hip structure, such as the shape of the greater trochanter, can also predispose individuals by changing how tendons interact with bone. Previous hip injuries, including trauma or surgery, may alter local anatomy and biomechanics, further increasing the risk.