This 1972 paper by Insall, Goldberg, and Salvati introduces the LP:LT ratio method for measuring patellar height on lateral radiographs and applies it to 77 operatively treated cases of recurrent patellar dislocation compared to 114 normal knees, asking whether patella alta is a consistent finding in instability and whether the ratio can guide the extent of surgical correction.
When evaluating a young patient with recurrent patellar dislocation, measure the Insall-Salvati ratio (LT:LP) on the lateral radiograph — a ratio >1.2 indicates patella alta and should prompt consideration of distal tubercle transfer rather than soft-tissue-only realignment.
This 1972 paper by Insall, Goldberg, and Salvati introduces the LP:LT ratio method for measuring patellar height on lateral radiographs and applies it to 77 operatively treated cases of recurrent patellar dislocation compared to 114 normal knees, asking whether patella alta is a consistent finding in instability and whether the ratio can guide the extent of surgical correction.
When evaluating a young patient with recurrent patellar dislocation, measure the Insall-Salvati ratio (LT:LP) on the lateral radiograph — a ratio >1.2 indicates patella alta and should prompt consideration of distal tubercle transfer rather than soft-tissue-only realignment.