Gas in the Musculoskeletal System: The Good and the Bad

Gas in the musculoskeletal system is frequently encountered in clinical practice and can indicate either a benign or nefarious process. Anaerobic infection is capable of producing gas in the musculoskeletal system; however, nonaggressive processes accounting for gas are much more common. In some instances, the presence of gas can be used to exclude a diagnosis of infection. Nitrogen gas bubble may be formed with joint manipulation,1–3 in volume loss and degeneration,4 and in traumatic dislocation/diastasis. The presence of gas with fracture is consistent with open fractures, which affect clinical management, and is associated with future complications.5 The referring or treating physician may also introduce gas through arthrocentesis, injection, or surgery. However, infection must always be considered with scrutiny of the radiologic records and correlation with the clinical history and physical examination so that proper treatment is not delayed. Therefore, it is important for the radiologist to recognize the presence of gas on imaging studies and have the expertise to appropriately raise clinical suspicion of infection or assign a typically benign cause to avoid unnecessary diagnostic evaluation and therapeutic procedures.