Knee motion in a long leg cast

Abstract

Five principles to reestablish static ligamentous sta bility are introduced, including secure, temporary, ti biofemoral fixation to protect against early postoper ative stretch or disruption. The necessity for empha sizing this point is demonstrated by a cadaver study. Knee motion in and out of long leg plaster casts was carefully studied in necropsy specimens. Casts ap plied over minimal or no padding allowed significant varus-valgus, anterior, posterior, and rotatory motion at the knee when manipulated manually. Medial open ing to valgus stress ranged from 64 to 100% after casting as compared to the amount of instability pres ent prior to casting. Legs with normally contoured thighs were not protected against anterior instability after casting, and an average of 48% of precasting rotational instability remained after casting.

We believe that these results are relevant to much knee ligament surgery. Current means for solving the problems posed by cast immobilization alone, includ ing case examples, are discussed.