{{Short description|Type of reduction in bone density}} '''Stress shielding''' is the reduction in bone density (osteopenia) as a result of removal of typical stress from the bone by an implant (for instance, the femoral component of a hip prosthesis).<ref>{{cite journal|last1=Ibrahim|first1=H.|last2=Esfahani|first2=S. N.|last3=Poorganji|first3=B.|last4=Dean|first4=D.|last5=Elahinia|first5=M.|title=Resorbable bone fixation alloys, forming, and post-fabrication treatments|journal=Materials Science and Engineering: C|date=January 2017|volume=70|issue=1|pages=870–888|doi=10.1016/j.msec.2016.09.069|pmid=27770965|url=https://zenodo.org/record/996947|doi-access=free}}</ref> This is because by Wolff's law,<ref>{{cite journal |year=1994 |last1=Frost |first1=HM |journal=The Angle Orthodontist |volume=64 |issue=3|pages=175–188 |pmid=8060014 |title=Wolff's Law and bone's structural adaptations to mechanical usage: an overview for clinicians |doi=10.1043/0003-3219(1994)064<0175:WLABSA>2.0.CO;2 }}</ref> bone in a healthy person or animal remodels in response to the loads it is placed under.
When a distal implant is used, forces are transferred to the implant from the proximal parts of the bone, thus shielding the latter close to the joint, resulting in bone atrophy. A proximal implant reduces this effect by applying more stress to the proximal portion of the bone. However, this leads to high proximal peak loads. Ideally, stress is applied evenly over the whole implant.<ref>{{Cite book|edition=2|title=Orthopädie und Unfallchirurgie essentials|url=http://www.thieme-connect.de/DOI/DOI?10.1055/b-002-35715|publisher=Georg Thieme Verlag|date=2013|location=Stuttgart|isbn=978-3-13-148442-0|doi=10.1055/b-0034-35163|language=de|editor-first=Steffen|editor-last=Ruchholtz|editor-first2=Dieter Christian|editor-last2=Wirtz}}</ref> The elastic modulus of human bone (3–20 GPa) varies,<ref>{{cite web |title=Mechanical properties of bone |url=https://www.doitpoms.ac.uk/tlplib/bones/bone_mechanical.php |website=University of Cambridge |access-date=21 March 2026}}</ref> but is closer to that of magnesium (41–45 GPa) than to those of titanium (110–127 GPa), stainless steel (189–205 GPa), iron (211.4 GPa), or zinc (78–121 GPa), so that magnesium implants can curtail stress-shielding phenomena;<ref>{{cite journal |last1=Kong |first1=Lingyun |last2=Heydari |first2=Zahra |last3=Lami |first3=Ghadeer Hazim |last4=Saberi |first4=Abbas |last5=Baltatu |first5=Madalina Simona |last6=Vizureanu |first6=Petrica |title=A Comprehensive Review of the Current Research Status of Biodegradable Zinc Alloys and Composites for Biomedical Applications |journal=Materials |date=3 July 2023 |volume=16 |issue=13 |page=4797 |doi=10.3390/ma16134797 |pmid=37445111 |pmc=10343804 |bibcode=2023Mate...16.4797K |doi-access=free }}</ref><ref>{{cite journal |last1=Saberi |first1=A. |last2=Bakhsheshi-Rad |first2=H.R. |last3=Karamian |first3=E. |last4=Kasiri-Asgarani |first4=M. |last5=Ghomi |first5=H. |title=Magnesium-graphene nano-platelet composites: Corrosion behavior, mechanical and biological properties |journal=Journal of Alloys and Compounds |date=April 2020 |volume=821 |article-number=153379 |doi=10.1016/j.jallcom.2019.153379 |s2cid=214172320 }}</ref> such implants are also bioresorbable.<ref>{{cite journal |last1=Hung |first1=Chun Ho |last2=Kwok |first2=Yui Chit |year=2025 |title=Bioabsorbable Magnesium-Based Materials Potential and Safety in Bone Surgery: A Systematic Review |url=https://www.mdpi.com/1943-3883/18/2/24 |journal=Craniomaxillofacial Trauma & Reconstruction |volume=18 |issue=2 |publisher=AO Foundation |page=24 |doi=10.3390/cmtr18020024 |doi-access=free|access-date=21 March 2026}}</ref> Porous implantation can also alleviate stress shielding.<ref>{{cite journal|last1=Dhandapani|first1=Ramya|last2=Krishnan|first2=Priya Dharshini|last3=Zennifer|first3=Allen|last4=Kannan|first4=Vishal|last5=Manigandan|first5=Amrutha|last6=Arul|first6=Michael R.|last7=Jaiswal|first7=Devina|last8=Subramanian|first8=Anuradha|last9=Kumbar|first9=Sangamesh Gurappa|last10=Sethuraman|first10=Swaminathan|title=Additive manufacturing of biodegradable porous orthopaedic screw|journal=Bioactive Materials|date=March 2020|volume=5|issue=3|pages=458–467|doi=10.1016/j.bioactmat.2020.03.009|pmid=32280835|pmc=7139166|url=}}</ref><ref>{{cite patent|country=US|number=5702449|status=patent|title=Reinforced porous spinal implants|pubdate=1997-12-30|gdate=1997-12-30|fdate=1995-06-07|pridate=1997-06-11|inventor=William F. McKay|assign1=Danek Medical, Inc., Memphis, Tenn.|assign2=SDGI Holdings Inc.}}</ref>
==References== {{reflist}}
Category:Orthopedic surgical procedures Category:Skeletal disorders
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