The fixation strength of hydroxyapatite-coated Schanz screws and standard stainless steel Schanz screws in lower extremity lengthening : a comparison based on a new torque value index: the fixation index

Archives of Orthopaedic and Trauma Surgery
R PlaczekA L Meiss

Abstract

Lengthening procedures are often complicated by loosening of pins. It has been reported that coating with hydroxyapatite improves fixation and reduces the rate of pin-track infection. We compared 47 hydroxyapatite-coated Schanz screws (HA screws) in 12 monolateral fixators mounted at the University Hospital Hamburg-Eppendorf with 45 standard stainless steel screws in 9 monolateral fixators mounted at the St Josefs-Hospital Wiesbaden by measuring the insertion and extraction torque values. The average implantation period was 7 months for the hydroxyapatite-coated screws and 5.4 months for the uncoated screws. We established the quotient of the maximum extraction torque over insertion torque which shows the change in the fixation strength with respect to time, the fixation index. It eliminates the influence of the varying pin-bone contact. There was no significant difference in the rate of infection. In the Schanz screws without signs of infection the index was 1.92 for the HA screws and 0.76 for the stainless steel screws (P = 0.0002) giving evidence of the improvement of the fixation by the coating. HA coating resulted in improved fixation of Schanz screws in bone and may be useful in prolonged external fixation of the lower le...Continue Reading

References

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May 1, 1998·The Journal of Bone and Joint Surgery. American Volume·A MoroniS Giannini
Jul 14, 2001·Clinical Orthopaedics and Related Research·A MoroniS Giannini
Jul 19, 2001·Biomedizinische Technik. Biomedical Engineering·R PlaczekA L Meiss
Jul 11, 2002·The Journal of Bone and Joint Surgery. American Volume·Axel PommerAndreas Dávid
Aug 5, 2004·Clinical Orthopaedics and Related Research·Antonio MoroniSandro Giannini

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Citations

Jan 15, 2011·Journal of Materials Science. Materials in Medicine·P RajeshHarikrishna Varma
Oct 12, 2012·Current Osteoporosis Reports·Clifford B Jones
Dec 20, 2013·International Journal of Molecular Sciences·Hirotaka MutsuzakiAtsuo Ito
Jun 7, 2017·Journal of Huazhong University of Science and Technology. Medical Sciences = Hua Zhong Ke Ji Da Xue Xue Bao. Yi Xue Ying De Wen Ban = Huazhong Keji Daxue Xuebao. Yixue Yingdewen Ban·Zi-Li WangKun Xiong
Nov 11, 2019·Journal of Materials Science. Materials in Medicine·Martin GathenRichard Placzek
Dec 17, 2009·Acta Biomaterialia·Sabrina D PuckettThomas J Webster

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