Atraumatic Instability and Surgical Technique

The normal hip has a natural tendency to stability due to its depth, congruency, and surrounding contractile and inert tissues. Hip instability may occur either with or without trauma. Hip microinstability may also occur with or without trauma. However, microinstability is a concept that is currently unproven, but sound anatomically, biomechanically, and radiographically, and with limited in vivo clinical studies. In the absence of other clear sources for persistent hip symptoms despite treatment, the astute clinician may diagnose microinstability. However, microinstability may also be the cause or the effect of other concomitant hip pathologies. If prior surgery has been performed, the operative report, photographs, and videos should be scrutinized in detail, especially in regard to osseous, chondrolabral, and capsuloligamentous management. Patients should be assessed for generalized hypermobility. Certain subjects (such as young female gymnasts, ballet, dance, yoga) may be at particular risk. Impingement-induced instability may also be an underlying contributor, especially in male patients with cam deformities. The examiner must assess the difference between laxity (asymptomatic) and instability (symptomatic). The true location of pain and tenderness, motion, and strength should be evaluated. Both radiographic and advanced imaging may be indicated. Initial management of microinstability should be nonoperative. In patients that have failed conservative treatment, arthroscopic evaluation for diagnostic and therapeutic purposes may be undertaken. Without femoroacetabular impingement or labral pathology, examination under anesthesia may better reveal subtle loss or excessive motion asymmetries. Capsulorrhaphy (plication) with or without ligamentum teres management may provide successful clinical outcome. Shortterm results are successful. However, midand long-term outcomes do not yet exist.