The diagnostic value of synovial membrane hemorrhage and bloody discoloration of synovial fluid ("inner knee sign") in autopsy cases of fatal hypothermia.

We describe and discuss autopsy findings of synovial membrane hemorrhage and bloody discoloration of synovial fluid ("inner knee sign") within a study population comprising 36 cases of fatal hypothermia and 300 control cases. Synovial membrane hemorrhage and bloody discoloration of synovial fluid of the knees were seen in 27 cases of fatal hypothermia (75%). Though we are not dealing here with an obligatory autopsy finding in fatal hypothermia, the detection of the inner knee sign might be used as another corroborative sign of vital hypothermia after considering all differential diagnostic aspects. However, the absence of this finding does not exclude death due to hypothermia.