Abstract
BackgroundThe implantation of screws is a standard procedure in musculoskeletal surgery. Heat can induce thermal osteonecrosis, damage the bone and lead to secondary problems like implant loosening and secondary fractures. The aim of this study was to investigate whether screw insertion generates temperatures that can cause osteonecrosis.MethodsWe measured the temperature of twenty human femur diaphysis in a total of 120 measurements, while screws of different material (stainless steel and titanium alloy) and different design (locking and cortex screw) were inserted in three different screwing modes (manual vs. machine screwing at full and reduced rotational speed) with 6 thermocouples (3 cis and 3 trans cortex). Each was placed at a depth of 2 mm with a distance of 1.5 mm from the outer surface of the screw.ResultsThe screw design (cortical > locking), the site of measurement (trans-cortex > cis-cortex) and the type of screw insertion (hand insertion > machine insertion) have an influence on the increase in bone temperature. The screw material (steel > titanium), the site of measurement (trans-cortex > cis-cortex) and the type of screw insertion (machine insertion > hand insertion) have an influence on the time needed to cool below critical temperature values. The combination of the two parameters (maximum temperature and cooling time), which is particularly critical for osteonecrosis, is found only at the trans-cortex.ConclusionInserting a screw hast the potential to increase the temperature of the surrounding bone tissue above critical values and therefore can induce osteonecrosis. The trans-cortex is the critical area for the development of temperatures above the osteonecrosis threshold, making effective cooling by irrigation difficult. It would be conceivable to cool the borehole with cold saline solution before inserting the screw or to cool the screw in cold saline solution. If possible, insertion by hand should be considered.
Highlights
The implantation of screws is a standard procedure in musculoskeletal surgery
The heat generation during several surgical procedures has the potential to irreversibly change and weaken the mechanical competency of the bone and could be one factor leading to damage such as screw and implant loosening resulting in construct failure, re-fracture, and delayed union or malunion [1, 2]
Image data given in Hounsfield unit (HU) was calibrated to volumetric Bone mineral density (BMD) values given in mg hydroxyapatite per ccm using a BMD phantom
Summary
The implantation of screws is a standard procedure in musculoskeletal surgery. Heat can induce thermal osteonecrosis, damage the bone and lead to secondary problems like implant loosening and secondary fractures. Drilling holes and placing screws is an essential step in most osteosynthesis. Paul et al BMC Musculoskelet Disord (2021) 22:841 that most surgeons are not aware of effects on bone. The heat generation during several surgical procedures (e.g. drilling) has the potential to irreversibly change and weaken the mechanical competency of the bone and could be one factor leading to damage such as screw and implant loosening resulting in construct failure, re-fracture, and delayed union or malunion [1, 2]
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