Outcome evaluation of new calcium titanate schanz-screws for external fixators. First clinical results and cadaver studies

  • Martin GathenEmail author
  • Milena Maria Ploeger
  • Max Jaenisch
  • Sebastian Koob
  • Davide Cucchi
  • Adnan Kasapovic
  • Thomas Randau
  • Richard Placzek
Clinical Applications of Biomaterials Original Research
Part of the following topical collections:
  1. Clinical Applications of Biomaterials



External fixators are important for correcting length discrepancies and axis deformities in pediatric or trauma orthopedic surgery. Pin loosening is a common pitfall during therapy that can lead to pain, infection, and necessary revisions. This study aims to present clinical data using calcium titanate (CaTiO3) Schanz screws and to measure the fixation strength.

Patients and methods

22 titanate screws were used for external fixators in 4 pediatric patients. Therapy was initiated to lengthen or correct axial deformities after congenital abnormalities. The maximum tightening torque was measured during implantation, and the loosening torque was measured during explantation. In addition, screws of the same type were used in a cadaver study and compared with stainless steel and hydroxyapatite-coated screws. 12 screws of each type were inserted in four tibias, and the loosening and tightening torque was documented.


The fixation index in the in vivo measurement showed a significant increase between screw insertion and extraction in three of the four patients. The pins were in situ for 91 to 150 days, and the torque increased significantly (P = 0.0004) from insertion to extraction. The cadaveric study showed lower extraction torques than insertion torques, as expected in this setting. The calculated fixation index was significantly higher in the CaTiO3 group than in the other groups (P = 0.0208 vs. HA and P < 0.0001 vs. steel) and in the HA group vs. plain steel group (P = 0.0448).


The calcium titanate screws showed favorable fixation strength compared to HA and stainless steel screws and should be considered in long-term therapy of external fixation.


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Ceroni D, Grumetz C, Desvachez O, Pusateri S, Dunand P, Samara E. From prevention of pin-tract infection to treatment of osteomyelitis during paediatric external fixation. J Child Orthop 2016;10:605–12.CrossRefGoogle Scholar
  2. 2.
    Moroni A, Pegreffi F, Cadossi M, Hoang-Kim A, Lio V, Giannini S. Hydroxyapatite-coated external fixation pins. Expert Rev Med Devices. 2005;2:465–71.CrossRefGoogle Scholar
  3. 3.
    Moroni A, Aspenberg P, Toksvig-Larsen S, Falzarano G, Giannini S. Enhanced fixation with hydroxyapatite coated pins. Clin Orthop 1998;346:171–7.CrossRefGoogle Scholar
  4. 4.
    Moroni A, Heikkila J, Magyar G, Toksvig-Larsen S, Giannini S. Fixation strength and pin tract infection of hydroxyapatite-coated tapered pins. Clin Orthop 2001;388:209–17.CrossRefGoogle Scholar
  5. 5.
    Saithna A. The influence of hydroxyapatite coating of external fixator pins on pin loosening and pin track infection: a systematic review. Injury. 2010;41:128–32.CrossRefGoogle Scholar
  6. 6.
    Coathup MJ, Blunn GW, Flynn N, Williams C, Thomas NP. A comparison of bone remodelling around hydroxyapatite-coated, porous-coated and grit-blasted hip replacements retrieved at post-mortem. J Bone Joint Surg Br 2001;83:118–23.CrossRefGoogle Scholar
  7. 7.
    Reikerås O. Femoral revision surgery using a fully hydroxyapatite-coated stem: a cohort study of twenty two to twenty seven years. Int Orthop 2017;41:271–5.CrossRefGoogle Scholar
  8. 8.
    Collier JP, Surprenant VA, Mayor MB, Wrona M, Jensen RE, Surprenant HP. Loss of hydroxyapatite coating on retrieved, total hip components. J Arthroplast 1993;8:389–93.CrossRefGoogle Scholar
  9. 9.
    Kokubo T, Yamaguchi S. Novel bioactive titanate layers formed on Ti metal and its alloys by chemical treatments. Materials. 2009;3:48–63.CrossRefGoogle Scholar
  10. 10.
    Placzek R, Ruffer M, Deuretzbacher G, Heijens E, Meiss AL. 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. Arch Orthop Trauma Surg 2006;126:369–73.CrossRefGoogle Scholar
  11. 11.
    Checketts RG, MacEachem AG, Otterbum M. Pin track infection and the principles of pin site care. In: De Bastiani G, Apley AG, Goldberg A, (eds) Orthofix external fixation in trauma and orthopaedics. London: Springer London; 2000. Scholar
  12. 12.
    Hedin H, Larsson S. Technique and considerations when using external fixation as a standard treatment of femoral fractures in children. Injury. 2004;35:1255–63.CrossRefGoogle Scholar
  13. 13.
    Kazmers NH, Fragomen AT, Rozbruch SR. Prevention of pin site infection in external fixation: a review of the literature. Strateg Trauma Limb Reconstr Online. 2016;11:75–85.CrossRefGoogle Scholar
  14. 14.
    Kizuki T, Matsushita T, Kokubo T. Antibacterial and bioactive calcium titanate layers formed on Ti metal and its alloys. J Mater Sci Mater Med 2014;25:1737–46.CrossRefGoogle Scholar
  15. 15.
    Coreño J, Coreño O. Evaluation of calcium titanate as apatite growth promoter. J Biomed Mater Res A 2005;75:478–84.CrossRefGoogle Scholar
  16. 16.
    Haenle M, Lindner T, Ellenrieder M, Willfahrt M, Schell H, Mittelmeier W, et al. Bony integration of titanium implants with a novel bioactive calcium titanate (Ca4Ti3O10) surface treatment in a rabbit model. J Biomed Mater Res A. 2012;100:2710–6.CrossRefGoogle Scholar
  17. 17.
    Braem A, Chaudhari A, Vivan Cardoso M, Schrooten J, Duyck J, Vleugels J. Peri- and intra-implant bone response to microporous Ti coatings with surface modification. Acta Biomater 2014;10:986–95.CrossRefGoogle Scholar
  18. 18.
    Placzek R, Hempfing A, Meiss AL. Evaluation of hydroxyapatite-coated Schanz screws in the Heidelberg external fixation system (HEFS). Biomed Tech. 2001;46:172–5.CrossRefGoogle Scholar
  19. 19.
    Ktistakis I, Guerado E, Giannoudis PV. Pin-site care: can we reduce the incidence of infections? Injury. 2015;46:S35–9.CrossRefGoogle Scholar
  20. 20.
    DeJong ES, DeBerardino TM, Brooks DE, Nelson BJ, Campbell AA, Bottoni CR, et al. Antimicrobial efficacy of external fixator pins coated with a lipid stabilized hydroxyapatite/chlorhexidine complex to prevent pin tract infection in a goat model. J Trauma. 2001;50:1008–14.CrossRefGoogle Scholar
  21. 21.
    Hosny G, Fadel M. Ilizarov external fixator for open fractures of the tibial shaft. Int Orthop 2003;27:303–6.CrossRefGoogle Scholar
  22. 22.
    Parameswaran AD, Roberts CS, Seligson D, Voor M. Pin tract infection with contemporary external fixation: how much of a problem? J Orthop Trauma. 2003;17:503–7.CrossRefGoogle Scholar
  23. 23.
    Britten S, Ghoz A, Duffield B, Giannoudis PV. Ilizarov fixator pin site care: the role of crusts in the prevention of infection. Injury. 2013;44:1275–8.CrossRefGoogle Scholar
  24. 24.
    Davies R, Holt N, Nayagam S. The care of pin sites with external fixation. J Bone Jt Surg Br 2005;87:716–9.CrossRefGoogle Scholar
  25. 25.
    Sian PS, Britten S, Duffield B. The care of pin sites with external fixation. J Bone Jt Surg Br 2006;88:558.CrossRefGoogle Scholar
  26. 26.
    Lethaby A, Temple J, Santy-Tomlinson J. Pin site care for preventing infections associated with external bone fixators and pins. Cochrane Database Syst Rev. 2013;12:CD004551.Google Scholar
  27. 27.
    Hohloch L, Konstantinidis L, Wagner FC, Strohm PC, Südkamp NP, Reising K. Biomechanical evaluation of a new technique for external fixation of unstable supracondylar humerus fractures in children. Technol Health Care J Eur Soc Eng Med 2015;23:453–61.CrossRefGoogle Scholar
  28. 28.
    Hohloch L, Konstantinidis L, Wagner FC, Strohm PC, Südkamp NP, Reising K. Biomechanical comparison of different external fixator configurations for stabilization of supracondylar humerus fractures in children. Clin Biomech Bristol Avon. 2016;32:118–23.CrossRefGoogle Scholar
  29. 29.
    Li W-C, Meng Q-X, Xu R-J, Cai G, Chen H, Li H-J. Biomechanical analysis between Orthofix® external fixator and different K-wire configurations for pediatric supracondylar humerus fractures. J Orthop Surg 2018;13:188.CrossRefGoogle Scholar
  30. 30.
    Grubor P, Grubor M, Asotic M. Comparison of stability of different types of external fixation. Med Arh 2011;65:157–9.CrossRefGoogle Scholar
  31. 31.
    Shirai T, Watanabe K, Matsubara H, Nomura I, Fujiwara H, Arai Y, et al. Prevention of pin tract infection with iodine-supported titanium pins, J. Orthop. Sci. J Jpn Orthop Assoc 2014;19:598–602.Google Scholar
  32. 32.
    Collinge CA, Goll G, Seligson D, Easley KJ. Pin tract infections: silver vs uncoated pins. Orthopedics. 1994;17:445–8.Google Scholar
  33. 33.
    Moroni A, Vannini F, Mosca M, Giannini S. State of the art review: techniques to avoid pin loosening and infection in external fixation. J Orthop Trauma. 2002;16:189–95.CrossRefGoogle Scholar
  34. 34.
    Manley MT, Hurst L, Hindes R, Dee R, Chiang FP. Effects of low-modulus coatings on pin-bone contact stresses in external fixation. J Orthop Res Publ Orthop Res Soc 1984;2:385–92.CrossRefGoogle Scholar
  35. 35.
    Voos K, Rosenberg B, Fagrhi M, Seligson D. Use of a tobramycin-impregnated polymethylmethacrylate pin sleeve for the prevention of pin-tract infection in goats. J Orthop Trauma. 1999;13:98–101.CrossRefGoogle Scholar
  36. 36.
    Lawes TJ, Scott JCR, Goodship AE. Increased insertion torque delays pin-bone interface loosening in external fixation with tapered bone screws. J Orthop Trauma. 2004;18:617–22.CrossRefGoogle Scholar
  37. 37.
    Pettine KA, Chao EY, Kelly PJ. Analfysis of the external fixator pin-bone interface. Clin Orthop 1993;293:18–27.Google Scholar
  38. 38.
    Aro HT, Markel MD, Chao EY. Cortical bone reactions at the interface of external fixation half-pins under different loading conditions. J Trauma. 1993;35:776–85.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Orthopedics and Trauma SurgeryUniversity Hospital of BonnBonnGermany

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