Influence of load carrying on loads in internal spinal fixators

After spinal stabilization with an implant, patients want to know whether c arrying loads will endanger their spine and their implant. Therefore, the e ffect of carrying a weight on the loading of internal spinal fixation devic es was determined in 10 patients using instrumented, telemeterized internal fixators. Patients carried a 5 kg dumbbell in one hand as well as up to 20 kg in both hands. Compared to normal standing carrying a weight caused onl y a slight increase of the fixator loads in all patients. The maximum flexi on bending moment in the fixators was then lower than during walking. Carry ing a weight even decreased the axial compression force in the fixators of the patients with the T11 or T12 vertebra bridged. Patients also raised the ir arms in anteversion while fielding weights of up to 5 kg with both hands . This increased the flexion bending moment in the fixators. Only a small p art of a carried weight is taken over by internal fixators. Carrying a shop ping bag only slightly increases the risk of pedicle screw breakage, howeve r, since the spine has to support most of the additional weight, it represe nts a risk with regard to correction loss and bone sintering. (C) 2000 Else vier Science Ltd. All rights reserved.