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Vet Comp Orthop Traumatol 2022; 35(05): 339-346
DOI: 10.1055/s-0042-1750431
Original Research

What Is the Cost of Off-Axis Insertion of Locking Screws? A Biomechanical Comparison of a 3.5 mm Fixed-Angle and 3.5 mm Variable-Angle Stainless Steel Locking Plate Systems

Jakub Kaczmarek
1   Tierklinik Elversberg, Elversberg, Germany
,
Tomasz Bartkowiak 
2   Poznan University of Technology, Faculty of Mechanical Engineering, Poznan, Poland
,
Piotr Paczos
2   Poznan University of Technology, Faculty of Mechanical Engineering, Poznan, Poland
,
Paweł Zawadzki
2   Poznan University of Technology, Faculty of Mechanical Engineering, Poznan, Poland
,
Daria Łączna
2   Poznan University of Technology, Faculty of Mechanical Engineering, Poznan, Poland
,
Bartosz Gapiński
2   Poznan University of Technology, Faculty of Mechanical Engineering, Poznan, Poland
› Author Affiliations Funding The works of T.B., P.P., P.Z., and B.G. were partially supported by the Ministry of Education and Science in Poland as a part of annual subsidy – project no. 0614/SBAD/1547.
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Abstract

Objective The aim of this study was to evaluate the effect of screw insertion angle and insertion torque on the mechanical properties of a 3.5 fixed-angle locking plate locking compression plate (LCP) and 3.5 variable-angle locking plate polyaxial locking system (PLS).

Methods In the LCP group, screws were placed abaxially at 0, 5 and 10 degrees. In the PLS group, screws were placed at 0, 5, 10, 15 and 20 degrees abaxially. The insertion torque was set to 1.5 and 2.5 Nm in the LCP and PLS groups respectively. A load was applied parallel to the screw axis, and the screw push-out force was measured until the locking mechanism was loosened.

Results The 3.5 LCP showed higher push-out strength than the 3.5 PLS when the screws were placed at 0 degree regardless of the insertion torque. The off-axis insertion of 3.5 LCP locking screws resulted in a significant decrease in push-out strength (p < 0.05). A higher insertion torque value significantly increased the screw holding strength for the 3.5 LCP (p < 0.05). The 3.5 PLS system had a significantly higher push-out force when the screws are at 0 degree than at 5, 10 and 15 degrees, and 20 degrees (p < 0.05) at any given insertion torque. An increase in the insertion torque did not have a significant effect on the push-out strength of the 3.5 PLS locking system.

Conclusion The 3.5 PLS is more sensitive to the screw insertion angle than to the insertion torque, whereas the 3.5 LCP is affected by both factors. Placing 3.5 LCP locking screws off-axis significantly reduces the screw holding strength; therefore, this approach has to be avoided. The findings of our research indicate that a 1.5 Nm torque can be used for a 3.5 PLS.

Keywords

polyaxial - locking screw - locking plate - insertion angle - insertion torque

Supplementary Material



Publication History

Received: 28 August 2021

Accepted: 04 May 2022

Article published online:
15 July 2022

© 2022. Thieme. All rights reserved.

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  • References

  • 1 Gautier E, Sommer C. Guidelines for the clinical application of the LCP. Injury 2003; 34 (Suppl. 02) B63-B76
    CrossrefPubMedGoogle Scholar
  • 2 Stoffel K, Dieter U, Stachowiak G, Gächter A, Kuster MS. Biomechanical testing of the LCP—how can stability in locked internal fixators be controlled?. Injury 2003; 34 (Suppl. 02) B11-B9
    CrossrefPubMedGoogle Scholar
  • 3 Bel JC. Pitfalls and limits of locking plates. Orthop Traumatol Surg Res 2019; 105 (1S): S103-S109
    CrossrefPubMedGoogle Scholar
  • 4 Boudreau B, Benamou J, von Pfeil DJF, Guillou RP, Beckett C, Déjardin LM. Effect of screw insertion torque on mechanical properties of four locking systems. Vet Surg 2013; 42 (05) 535-543
    CrossrefPubMedGoogle Scholar
  • 5 Boero Baroncelli A, Reif U, Bignardi C, Peirone B. Effect of screw insertion torque on push-out and cantilever bending properties of five different angle-stable systems. Vet Surg 2013; 42 (03) 308-315
    CrossrefPubMedGoogle Scholar
  • 6 Bufkin BW, Barnhart MD, Kazanovicz AJ, Naber SJ, Kennedy SC. The effect of screw angulation and insertion torque on the push-out strength of polyaxial locking screws and the single cycle to failure in bending of polyaxial locking plates. Vet Comp Orthop Traumatol 2013; 26 (03) 186-191
    Article in Thieme ConnectPubMedGoogle Scholar
  • 7 Gueorguiev B, Lenz M. Why and how do locking plates fail?. Injury 2018; 49 (Suppl. 01) S56-S60
    CrossrefPubMedGoogle Scholar
  • 8 Cabassu JB, Kowaleski MP, Skorinko JK, Blake CA, Gaudette GR, Boudrieau RJ. Single cycle to failure in torsion of three standard and five locking plate constructs. Vet Comp Orthop Traumatol 2011; 24 (06) 418-425
    Article in Thieme ConnectPubMedGoogle Scholar
  • 9 Gallagher B, Silva MJ, Ricci WM. Effect of off-axis screw insertion, insertion torque, and plate contouring on locked screw strength. J Orthop Trauma 2014; 28 (07) 427-432
    CrossrefPubMedGoogle Scholar
  • 10 Sandriesser S, Rupp M, Greinwald M, Heiss C, Augat P, Alt V. Locking design affects the jamming of screws in locking plates. Injury 2018; 49 (Suppl. 01) S61-S65
    CrossrefPubMedGoogle Scholar
  • 11 Jung HJ, Jang A, Yim HJ, Han CH, Lee JH. Effect of screw insertion torque on mechanical properties of a hybrid polyaxial locking system. Vet Comp Orthop Traumatol 2021; 34 (01) 17-23
    Article in Thieme ConnectPubMedGoogle Scholar
  • 12 Schoch B, Hast MW, Mehta S, Namdari S. Not all polyaxial locking screw technologies are created equal: a systematic review of the literature. JBJS Rev 2018; 6 (01) e6
    CrossrefPubMedGoogle Scholar
  • 13 Bassanino J, Kaczmarek J, Boursier JF. et al. Radiographically confirmed outcomes after fracture repair with a PLS polyaxial locking system in 40 dogs and cats. Vet Surg 2021; 50 (03) 571-578
    CrossrefPubMedGoogle Scholar
  • 14 Barnhart MD, Rides CF, Kennedy SC. et al. Fracture repair using a polyaxial locking plate system (PAX). Vet Surg 2013; 42 (01) 60-66
    CrossrefPubMedGoogle Scholar
  • 15 Tomlinson AW, Comerford EJ, Birch RS, Innes JF, Walton MB. Mechanical performance in axial compression of a titanium polyaxial locking plate system in a fracture gap model. Vet Comp Orthop Traumatol 2015; 28 (02) 88-94
    Article in Thieme ConnectPubMedGoogle Scholar
  • 16 Blake CA, Boudrieau RJ, Torrance BS. et al. Single cycle to failure in bending of three standard and five locking plates and plate constructs. Vet Comp Orthop Traumatol 2011; 24 (06) 408-417
    Article in Thieme ConnectPubMedGoogle Scholar
  • 17 Kaczmarek J, Bartkowiak T, Schuenemann R. et al. Mechanical performance of a polyaxial locking plate and the influence of screw angulation in a fracture gap model. Vet Comp Orthop Traumatol 2020; 33 (01) 36-44
    Article in Thieme ConnectPubMedGoogle Scholar
  • 18 Scrimgeour AB, Craig A, Witte PG. Locking T-plate repair of ilial fractures in cats and small dogs. Vet Comp Orthop Traumatol 2017; 30 (06) 453-460
    Article in Thieme ConnectPubMedGoogle Scholar
  • 19 Boulton CL, Kim H, Shah SB. et al. Do locking screws work in plates bent at holes?. J Orthop Trauma 2014; 28 (04) 189-194
    CrossrefPubMedGoogle Scholar
  • 20 Kaczmarek J, Bartkowiak T, Paczos P, Gapinski B, Jader H, Unger M. How do the locking screws lock? A micro-CT study of 3.5-mm locking screw mechanism. Vet Comp Orthop Traumatol 2020; 33 (05) 316-326
    Article in Thieme ConnectPubMedGoogle Scholar
  • 21 Kääb MJ, Frenk A, Schmeling A, Schaser K, Schütz M, Haas NP. Locked internal fixator: sensitivity of screw/plate stability to the correct insertion angle of the screw. J Orthop Trauma 2004; 18 (08) 483-487
    CrossrefPubMedGoogle Scholar
  • 22 Cartner JL, Petteys T, Tornetta 3rd P. Mechanical effects of off-axis insertion of locking screws: should we do it?. J Orthop Trauma 2014; 28 Suppl 1: S2-S5
    CrossrefPubMedGoogle Scholar
  • 23 Egol KA, Kubiak EN, Fulkerson E, Kummer FJ, Koval KJ. Biomechanics of locked plates and screws. J Orthop Trauma 2004; 18 (08) 488-493
    CrossrefPubMedGoogle Scholar