Clinical Biomechanics 14 (1999) 97-102 Braces do not reduce loads on internal spinal fixation devices A. Rohlmanna*, G. Bergmann, F. Graichen, G. Neff Orthopaedic Hospital of the Free Universi& of Berlin, Oskar-Helene-Heinz, Clayallee 229, D- I4195 Berlin, Germany Abstract Objective. To determine the effect of a brace or harness on loads on internal spinal fixation devices. Design. The implant loads were measured in viva using telemeterized internal spinal fixators. Background. Onty limited information exists regarding the load reduction due to a brace or harness. Methods. A Boston overlap brace, a reclination brace, and a lumbotrain harness were examined to determine how they affect the loads on internal spinal fixation devices. The implant loads were measured using telemeterized fixators in six patients for several positions and activities, including sitting, standing, walking, bending forward, and lifting an extended leg in a supine position. Results. None of the braces studied were able to markedly reduce the loads on the fixators. Frequently even higher fixator loads were -measured when wearing a brace or harness. Conclusions. It does not seem helpful to brace patients after mono- or bisegmental stabilization of the lumbar spine. Relevance Braces are used in patients treated with an internal spinal fixation device. They are often uncomfortable for the patients and cause additional cost. Our study showed that braces have only a negligible effect on Iixator loads. 0 1999 Elsevier Science Ltd. All rights reserved. Keywor& Spine; Spinal orthoses; Internal spinal fixator; Load measurement; Telemetry 1. Introduction Fractures in the thoracolumbar spine and degenera- tive instabilities in the lumbar region can be success- fully treated by an internal spinal fixation device [l]. Breakage and loosening of pedicle screws several months after implantation are complications described. Some surgeons try to avoid this problem by supplying their patients with a brace. However, the effect of such a brace on implant loads is not known. The goals of an orthosis may be any combination of support, rest, immobilization, protection, correction and reminder. Support and/or immobilization are the main goals of a brace after stabilization of the lumbar spine [2]. Norton and Brown [3] inserted Kirschner wires in the spinous processes and investigated spinal movement in several braces using radiographs and photographs. The,y found that the braces tested only limited interspace flexion but never achieved immobili- zation. Maier [4] made functional radiographs in *Corresponding au1 hor. patients wearing various spinal orthoses. He observed that the reclination brace markedly reduced dorsoan- terior motion when fitted perfectly. There was no reduction of lateral bending motion. Nachemson and Morris [5] measured the intradiscal pressure in four subjects with normal discs when wearing a corset containing an inflatable pad. In all cases they found a considerable decrease in the total load on the disc studied when the corset was inflated to the subject’s tolerance limit. Different loads act on the spine in the course of daily life. Rohlmann et al. [6-91 have measured the loads on internal spinal fixation devices during many activities. The implants were mostly loaded in axial compression and flexion bending. The implant loads differed from patient to patient as well as before and after anterior interbody fusion. The aim of this study was to determine the extent to which implant loads can be reduced by braces. Implant loads were thus measured for several activities, including sitting, standing, walking, bending forward, and lifting an extended leg in a supine position. The 026%0033/99/$ - see iront matter 0 1999Elsevier Science Ltd. All rights reserved. PII: SO268-0033(9~~)00056-4