2019 Arthroscopy Journal
Snapping syndromes are caused by 2 adjacent anatomic structures having a frictional catching, which may be associated with an audible pop. At the knee, they may have an intra- or extra-articular origin. It is imperative to understand the etiology of the snapping to avoid unnecessary surgery.
Snapping symptoms affect the lateral aspect of the knee in most cases, and occurrence of snapping around the medial side of the joint is more uncommon. The literature includes reports of snapping of the semitendinosus tendon alone4 or in combination with semimembranosus tendons or the gracilis tendon. The diagnosis of semitendinosus tendon snapping is difficult to make because of the rare description of this syndrome in the literature. It may be based on the history and findings from a physical examination8 but may not be possible to detect with magnetic resonance imaging (MRI). In fact, Karataglis and de la Hera Cremades report no MRI abnormalities in their patients.
Routine MRI usually requires a resting position and produces static images that may show abnormal findings with limited precision. Because the snapping phenomenon occurs during movement, dynamic imaging may be superior for diagnostic confirmation and identification of the structure responsible for a patient’s symptoms. Dynamic ultrasonography may be a useful tool in the diagnosis of medial hamstring snapping. Because of the paucity of scientific data on this phenomenon, the etiology of such symptoms is often undetermined, and surgical procedures for treating this condition are variable.