Posterior antiglide plates recently have been introduced as a method of fixation for the short oblique fracture (Type B, as defined by the AO Group) of the distal part of the fibula. This method has several advantages over the more commonly used lateral plate for the fixation of this type of fracture, including dissection of a smaller area and less operative time, minimum bending of the plate, and no potential for penetration of a screw into the joint. The system can also be applied without insertion of a screw into the distal fragment. This prompted us to compare the biomechanical properties of fixation with the antiglide and lateral plating systems. Short oblique fractures of the distal part of the fibula were produced mechanically in cadaveric legs by supination and external rotation of the foot. The torque that was necessary to produce the fracture in each of twenty-four fibulae was recorded. After fracture, each fibula was reduced anatomically and fixed internally with a lateral plate or antiglide plate applied posteriorly. The strength of fixation was measured by restressing the legs until failure of fixation occurred. The stiffness of the fixation system and the amount of energy required to produce failure of fixation were also calculated. The system using the lateral plate for fixation failed when the torque reached an average of 64.3 per cent of the torque that produced the fracture.(ABSTRACT TRUNCATED AT 250 WORDS)