A New Augmentation Method for Improved Screw Fixation in Fragile Bone

Deepak Bushan Raina; Vetra Markevičiūtė; Mindaugas Stravinskas; Joeri Kok; Ida Jacobson; Yang Liu; Erdem Aras Sezgin; Hanna Isaksson; Stefan Zwingenberger; Magnus Tägil; Šarūnas Tarasevičius; Lars Lidgren

doi:10.3389/fbioe.2022.816250

A New Augmentation Method for Improved Screw Fixation in Fragile Bone

Front Bioeng Biotechnol. 2022 Mar 2:10:816250. doi: 10.3389/fbioe.2022.816250. eCollection 2022.

Affiliations

¹ Department of Clinical Sciences Lund, Orthopedics, The Faculty of Medicine, Lund University, Lund, Sweden.
² Department of Orthopedics and Traumatology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
³ Department of Biomedical Engineering, Lund University, Lund, Sweden.
⁴ Department of Orthopedics and Traumatology, Faculty of Medicine, Aksaray University, Aksaray, Turkey.
⁵ University Hospital Carl Gustav Carus at Technische Universität Dresden, University Center of Orthopedic, Trauma and Plastic Surgery, Dresden, Germany.

Abstract

Pertrochanteric fractures (TF) due to osteoporosis constitute nearly half of all proximal femur fractures. TFs are treated with a surgical approach and fracture fixation is achieved using metallic fixation devices. Poor quality cancellous bone in osteoporotic patients makes anchorage of a fixation device challenging, which can lead to failure of the fracture fixation. Methods to reinforce the bone-implant interface using bone cement (PMMA) and other calcium phosphate cements in TFs have been described earlier but a clear evidence on the advantage of using such biomaterials for augmentation is weak. Furthermore, there is no standardized technique for delivering these biomaterials at the bone-implant interface. In this study, we firstly describe a method to deliver a calcium sulphate/hydroxyapatite (CaS/HA) based biomaterial for the augmentation of a lag-screw commonly used for TF fixation. We then used an osteoporotic Sawbones model to study the consequence of CaS/HA augmentation on the immediate mechanical anchorage of the lag-screw to osteoporotic bone. Finally, as a proof-of-concept, the method of delivering the CaS/HA biomaterial at the bone-implant interface as well as spreading of the CaS/HA material at this interface was tested in patients undergoing treatment for TF as well as in donated femoral heads. The mechanical testing results indicated that the CaS/HA based biomaterial increased the peak extraction force of the lag-screw by 4 times compared with un-augmented lag-screws and the results were at par with PMMA. The X-ray images from the patient series showed that it was possible to inject the CaS/HA material at the bone-implant interface without applying additional pressure and the CaS/HA material spreading was observed at the interface of the lag-screw threads and the bone. Finally, the spreading of the CaS/HA material was also verified on donated femoral heads and micro-CT imaging indicated that the entire length of the lag-screw threads was covered with the CaS/HA biomaterial. In conclusion, we present a novel method for augmenting a lag-screw in TFs, which could potentially reduce the risk of fracture fixation failure and reoperation in fragile osteoporotic patients.

Keywords: biomaterial; hip fracture; implant augmentation; implant integration; osteoporosis.