Treatment of Excessive Tibial Plateau Angle 255(A) (B) (C)Figure 30.2 Safe and required rotation. The osteotomy is positioned (black dashed line) and a line perpendicular to the
tibial crest is drawn at the level of patellar tendon insertion (white line) (A). The safe distance, S (white double-ended
arrow), is the linear distance (chord) from the osteotomy exit at the cranial intercondyloid area to the intersection of the
line drawn perpendicular to the tibial crest at the patellar tendon insertion, referred to as the safe point (A). The tibial
plateau segment has been rotated to the safe point (safe rotation) (B). The tibial plateau segment has been rotated well
below the safe point (required rotation) to achieve a tibial plateau angle of 5◦(C).
(proximal tibial joint reference line) or at
any location between these two points (Fig-
ure 30.2A). The location is selected that opti-
mizes the tibial tuberosity and tibial plateau
size and shape. In cases of severe tibial defor-
mity, alternate tibial osteotomy locations may
be needed (Figures 30.1C and 30.2A). Once the
tibial osteotomy is properly positioned, a line is
drawn caudally from the patellar tendon inser-
tion on the tibial tuberosity, perpendicular to the
tibial crest to intersect with the osteotomy tem-
plate (Figure 30.2A). The linear distance from
the point at which the osteotomy exits the tibia
within the cranial intercondyloid area to the
intersection of the line drawn perpendicular to
the tibial crest at the point of patellar tendon
insertion and the osteotomy template is the safe
rotation distance (S in Figure 30.2A).
The safe TPA (sTPA) is the tibial plateau
angle that can be treated by this magnitude of