Three hundred six tibial plateau fractures treated at the authors' institutions and in private practice were analyzed in relation to the use of a cast brace or fracture brace. One hundred forty-one of these patients had had a cast brace or fracture brace as part of their treatment program, either as the primary fracture treatment or after open reduction or traction. The aims of this study were (1) to determine if cast bracing could maintain alignment, fracture position, and range of motion and (2) to compare its results with those of other major long-term studies of similar fractures. There were 85 lateral, 24 medial, and 32 bicondylar fractures. Cast bracing was used for one to 17 weeks, with a mean of eight weeks. Ninety-nine of the 141 patients were followed for at least one year. Eighty-two of the patients maintained alignment with less than 5 degrees of deformity, and fracture position was maintained in 85% of cases, with only 15% having 4-8 mm of loss of position. Medial plateau and subcondylar fractures had an increased incidence of fracture position loss. Ninety-seven percent of patients had greater than 90 degrees of flexion, and 90% had full extension, i.e., less than 5 degrees of contracture. Pain was minimal or absent after heavy exercise in 90% of patients using cast bracing. Arthritic changes on roentgenographic analysis were absent or mild in 93.5% and moderate or severe in 6.5% of patients. Complications, including phlebitis, pulmonary emboli, wound infection, hardware slippage, and skin slough, occurred in nine patients.(ABSTRACT TRUNCATED AT 250 WORDS)