Stress shielding explained

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).^[1] This is because by Wolff's law,^[2] 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 proximal parts of the bone, thus shielding the proximal part of the bone 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.^[3] It is possible to mention the elastic modulus of magnesium (41–45 GPa) compared to titanium (110–127 GPa), stainless steel (189–205 GPa), iron (211.4 GPa), or zinc (78–121 GPa), which makes it further analogous to the natural bone of the body (3–20 GPa) and prevents stress shielding phenomena.^{[4] [5]} Porous implantation is one typical alleviation method.^{[6] [7]}

Notes and References

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2. 1994 . Frost . HM . The Angle Orthodontist . 64 . 3. 175–188 . 8060014 . Wolff's Law and bone's structural adaptations to mechanical usage: an overview for clinicians . 10.1043/0003-3219(1994)064<0175:WLABSA>2.0.CO;2 .
3. Book: 2. Orthopädie und Unfallchirurgie essentials. Georg Thieme Verlag. 2013. Stuttgart. 978-3-13-148442-0. 10.1055/b-0034-35163. de. Steffen. Ruchholtz. Dieter Christian. Wirtz.
4. Kong . Lingyun . Heydari . Zahra . Lami . Ghadeer Hazim . Saberi . Abbas . Baltatu . Madalina Simona . Vizureanu . Petrica . A Comprehensive Review of the Current Research Status of Biodegradable Zinc Alloys and Composites for Biomedical Applications . Materials . 3 July 2023 . 16 . 13 . 4797 . 10.3390/ma16134797 . 37445111 . 10343804 . 2023Mate...16.4797K . free .
5. Saberi . A. . Bakhsheshi-Rad . H.R. . Karamian . E. . Kasiri-Asgarani . M. . Ghomi . H. . Magnesium-graphene nano-platelet composites: Corrosion behavior, mechanical and biological properties . Journal of Alloys and Compounds . April 2020 . 821 . 153379 . 10.1016/j.jallcom.2019.153379 . 214172320 .
6. Dhandapani. Ramya. Krishnan. Priya Dharshini. Zennifer. Allen. Kannan. Vishal. Manigandan. Amrutha. Arul. Michael R.. Jaiswal. Devina. Subramanian. Anuradha. Kumbar. Sangamesh Gurappa. Sethuraman. Swaminathan. Additive manufacturing of biodegradable porous orthopaedic screw. Bioactive Materials. March 2020. 5. 3. 458–467. 10.1016/j.bioactmat.2020.03.009. 32280835. 7139166.
7. US. 5702449. patent. Reinforced porous spinal implants. 1997-12-30. 1997-12-30. 1995-06-07. 1997-06-11. William F. McKay. Danek Medical, Inc., Memphis, Tenn.. SDGI Holdings Inc..