Foreign body detection in musculoskeletal Injuries: A in vitro blinded study comparing sensitivity among digital radiography, ultrasonography, CT and magnetic resonance imaging

Common organic materials like thorns, wood and sand constitute routine accident scene flora and comprise a large percentage of foreign bodies. These low radiopaque foreign bodies present a diagnostic challenge and are routinely missed. In musculoskeletal injuries, failure to detect these foreign bodies may lead to infection, morbidity and patient dissatisfaction. A universal investigation protocol for foreign body detection is lacking. This study was initiated to compare the effectiveness of Digital radiography, CT, MRI and Hi-Frequency ultrasound for foreign body detection in In-vitro (goat thigh specimens) and to formulate a foreign body detection protocol which is universal and practical to use especially for setups in country like ours. Eight materials selected were wood, plastic, sand, metal (steel), glass, stone, teeth and fiber plastic. Foreign bodies placed into the muscle and bone-muscle interface. Digital radiography, Ultrasonography, CT and MRI imaging methods performed. Conventional radiography is established screening modality for radiopaque foreign bodies, which were visualized with all 4 modalities. USG is a useful tool for superficial and deep (within 3 cms) low radiopaque foreign bodies (Wood, sand, fiber plastic). CT provides accurate information regarding dimensions and orientation of deeper foreign bodies. MRI has high intra-observer variations, is an expensive tool which might not be available at all the centers and time. Radiography as a primary tool teamed up by Ultrasonography can detect almost all routine foreign bodies. CT/MRI may follow if intervention is planned or information regarding size, orientation and location is desired based on availability. Successful detection requires detailed patient’s information and suspected nature of foreign body or accident site. Our protocol should guide to successful management of a patient with retained foreign body.