Frédéric Cornaz1,2, Jonas Widmer3,4, Jess Gerrit Snedeker3,4, José Miguel Spirig3, Mazda Farshad3. 1. Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland. frederic.cornaz@balgrist.ch. 2. Institute for Biomechanics, Balgrist Campus, ETH Zurich, Lengghalde 5, CH-8008, Zurich, Switzerland. frederic.cornaz@balgrist.ch. 3. Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland. 4. Institute for Biomechanics, Balgrist Campus, ETH Zurich, Lengghalde 5, CH-8008, Zurich, Switzerland.
Abstract
PURPOSE: Dorsal screw-rod instrumentations are used for a variety of spinal disorders. Cross-links (CL) can be added to such constructs, however, no clear recommendations exist. This study aims to provide an overview of the available evidence on the effectiveness of CL, potentially allowing to formulate recommendations on their use. METHODS: A systematic literature review was performed on PubMed and 37 original articles were included and grouped into mechanical, biomechanical, finite element and clinical studies. The change in range of motion (ROM) was analyzed in mechanical and biomechanical studies, ROM, stiffness and stress distribution were evaluated in finite element studies and clinical outcome parameters were analyzed in clinical studies. RESULTS: A relative consistent reduction in ROM in axial rotation with CL-augmentation was reported, while minor and less consistent effects were observed in flexion-extension and lateral bending. The use of CLs was clinical beneficial in C1/2 fusion, while the limited clinical studies on other anatomic regions show no significant benefit for CL-augmentation. CONCLUSION: While CL provides some additional axial rotation stability in most situations, lateral bending and flexion-extension are less affected. Based on clinical data, CL-augmentation can only be recommended for C1/2 instrumentations, while for other cases, further clinical studies are needed to allow for evidence-based recommendations.
PURPOSE: Dorsal screw-rod instrumentations are used for a variety of spinal disorders. Cross-links (CL) can be added to such constructs, however, no clear recommendations exist. This study aims to provide an overview of the available evidence on the effectiveness of CL, potentially allowing to formulate recommendations on their use. METHODS: A systematic literature review was performed on PubMed and 37 original articles were included and grouped into mechanical, biomechanical, finite element and clinical studies. The change in range of motion (ROM) was analyzed in mechanical and biomechanical studies, ROM, stiffness and stress distribution were evaluated in finite element studies and clinical outcome parameters were analyzed in clinical studies. RESULTS: A relative consistent reduction in ROM in axial rotation with CL-augmentation was reported, while minor and less consistent effects were observed in flexion-extension and lateral bending. The use of CLs was clinical beneficial in C1/2 fusion, while the limited clinical studies on other anatomic regions show no significant benefit for CL-augmentation. CONCLUSION: While CL provides some additional axial rotation stability in most situations, lateral bending and flexion-extension are less affected. Based on clinical data, CL-augmentation can only be recommended for C1/2 instrumentations, while for other cases, further clinical studies are needed to allow for evidence-based recommendations.
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Authors: Marco D Burkhard; Frédéric Cornaz; José Miguel Spirig; Florian Wanivenhaus; Rafael Loucas; Marie-Rosa Fasser; Jonas Widmer; Mazda Farshad Journal: N Am Spine Soc J Date: 2021-11-17