Radionuclide imaging in internal derangements of the knee.

The clinical specificity and sensitivity of imaging with 99mTc was evaluated prospectively in 104 consecutive patients admitted to the hospital for diagnostic/surgical arthroscopy. Four distinct patterns of radionuclide activity were seen that correlated with observed arthroscopic findings. These patterns of activity were seen with degenerative joint disease (DJD) or severe rotational instability, meniscal pathology, fracture of the subchondral plate or full thickness cartilaginous ulceration, and synovitis. Radionuclide imaging was seen to be extremely sensitive and highly specific for all four patterns of activity. The observed association of subchondral plate injury with meniscal pathology may present an explanation for the observed poor outcome in a limited number of patients following meniscectomy.