Unicortical Versus Bicortical Proximal Locking Screw for Prevention of Peri-Implant Fracture: A Biomechanical Analysis of an Osteoporotic Distal Radius Model

Overview

Journal J Hand Surg Glob Online

Date 2024 Dec 20

PMID 39703601

Authors

Mitchell C Harris

Ryan J Bickley

Pooyan Abbasi

Gabriel J Yohe

Kenneth R Means

Scott M Tintle

Aviram M Giladi

Affiliations

Soon will be listed here.

Abstract

Purpose: Osteoporotic patients are at risk of peri-implant fractures after distal radius fixation. A unicortical screw in the proximal hole of the plate can theoretically decrease stress riser formation by eliminating the hole in the far bone cortex. This construct has been proposed in orthopedic literature to prevent peri-implant fractures but has not been tested in an osteoporotic distal radius model.

Methods: Eleven paired cadaver radii were harvested and plated with four-hole titanium volar distal radius plates. No osteotomies were created. The fixation constructs were identical except that group A used a bicortical proximal locking screw and group B used a unicortical proximal locking screw. Bone mineral density was estimated using radiographic measurements. The samples were potted and tested for four-point bending stiffness, torsion stiffness, and load to failure.

Results: Between the bicortical and unicortical screw groups, there was no significant difference in four-point bending stiffness (110.8 vs 106.2 N/mm, apex volar bending; 105.4 vs 107.1 N/mm, apex dorsal bending) or torsional stiffness (430.6 vs 427.6 N-mm/degree, internal rotation; 430.8 vs 429.7 N-mm/degree, external rotation). There was also no significant difference in load to failure with apex dorsal four-point bending (795.3 vs 770.0 N).

Conclusions: This study shows that a healed osteoporotic distal radius volar plate construct with a proximal unicortical locking screw is not statistically different from a bicortical screw in stiffness or load to failure in apex dorsal bending. Although a unicortical locking screw has been proposed as a mechanism to prevent stress risers at the proximal aspect of the distal radius plate, this study suggests no significant difference when compared with a bicortical locking screw.

Clinical Relevance: There is no significant biomechanical advantage to unicortical over bicortical locking screws in the proximal hole of a distal radius plate to prevent diaphyseal peri-implant fractures in osteoporotic patients.

References

Chan L, Gardner A, Wong M, Chua K, Kwek E . Non-prosthetic peri-implant fractures: classification, management and outcomes. Arch Orthop Trauma Surg. 2018; 138(6):791-802. DOI: 10.1007/s00402-018-2905-1. View

Overturf S, Morris R, Gugala Z, Lindsey R . Biomechanical comparison of bicortical locking versus unicortical far-cortex-abutting locking screw-plate fixation for comminuted radial shaft fractures. J Hand Surg Am. 2014; 39(10):1907-13. DOI: 10.1016/j.jhsa.2014.06.141. View

Freeman A, Tornetta 3rd P, Schmidt A, Bechtold J, Ricci W, Fleming M . How much do locked screws add to the fixation of "hybrid" plate constructs in osteoporotic bone?. J Orthop Trauma. 2010; 24(3):163-9. DOI: 10.1097/BOT.0b013e3181d35c29. View

Barrera-Ochoa S, Nunez J, Mir X . Peri-implant radial and ulnar shaft fractures after volar locking plate fixation of the distal radius. J Hand Surg Eur Vol. 2017; 43(2):209-210. DOI: 10.1177/1753193417709988. View

Beltran M, Collinge C, Gardner M . Stress Modulation of Fracture Fixation Implants. J Am Acad Orthop Surg. 2016; 24(10):711-9. DOI: 10.5435/JAAOS-D-15-00175. View

Peck J, Charpentier P, Flanagan B, Srivastava A, Atkinson P . Reducing Fracture Risk Adjacent to a Plate With an Angulated Locked End Screw. J Orthop Trauma. 2015; 29(11):e431-6. DOI: 10.1097/BOT.0000000000000384. View

Snoddy M, An T, Hooe B, Kay H, Lee D, Pappas N . Incidence and reasons for hardware removal following operative fixation of distal radius fractures. J Hand Surg Am. 2015; 40(3):505-7. DOI: 10.1016/j.jhsa.2014.11.022. View

Kistler J, Lutsky K, Matzon J . Surgical Outcomes Following Fixation of Peri-Implant Distal Radius Fractures: A Case Series. J Hand Surg Am. 2021; 47(2):192.e1-192.e6. DOI: 10.1016/j.jhsa.2021.04.016. View

Roberts J, Grindel S, Rebholz B, Wang M . Biomechanical evaluation of locking plate radial shaft fixation: unicortical locking fixation versus mixed bicortical and unicortical fixation in a sawbone model. J Hand Surg Am. 2007; 32(7):971-5. DOI: 10.1016/j.jhsa.2007.05.019. View

10.

Davenport S, Lindsey R, Leggon R, Miclau T, Panjabi M . Dynamic compression plate fixation: a biomechanical comparison of unicortical vs bicortical distal screw fixation. J Orthop Trauma. 1988; 2(2):146-50. View

11.

Park K, Lim S, Song Y, Hwang K . Factors affecting peri-implant fracture following locking plate for osteoporotic distal femur fractures. Orthop Traumatol Surg Res. 2017; 103(8):1201-1204. DOI: 10.1016/j.otsr.2017.08.008. View

12.

Bockmann B, Budak C, Figiel J, Lechler P, Bliemel C, Debus F . Is there a benefit of proximal locking screws in osteoporotic distal radius fractures? - A biomechanical study. Injury. 2016; 47(8):1631-5. DOI: 10.1016/j.injury.2016.04.005. View

13.

Beaupre G, Giori N, Caler W, Csongradi J . A comparison of unicortical and bicortical end screw attachment of fracture fixation plates. J Orthop Trauma. 1992; 6(3):294-300. DOI: 10.1097/00005131-199209000-00005. View

14.

Stramazzo L, Rovere G, Cioffi A, Vigni G, Galvano N, DArienzo A . Peri-Implant Distal Radius Fracture: Proposal of a New Classification. J Clin Med. 2022; 11(9). PMC: 9105785. DOI: 10.3390/jcm11092628. View

15.

Liodaki E, Wendlandt R, Waizner K, Schopp B, Mailander P, Stang F . A biomechanical analysis of plate fixation using unicortical and bicortical screws in transverse metacarpal fracture models subjected to 4-point bending and dynamical bending test. Medicine (Baltimore). 2017; 96(27):e6926. PMC: 5502133. DOI: 10.1097/MD.0000000000006926. View

16.

Stramazzo L, Cioffi A, Rovere G, Vigni G, Galvano N, Salli M . A rare case of peri-implant distal radius fracture. Trauma Case Rep. 2020; 31:100387. PMC: 7735967. DOI: 10.1016/j.tcr.2020.100387. View

17.

Solgaard S, Petersen V . Epidemiology of distal radius fractures. Acta Orthop Scand. 1985; 56(5):391-3. DOI: 10.3109/17453678508994354. View

18.

Wilcke M, Hammarberg H, Adolphson P . Epidemiology and changed surgical treatment methods for fractures of the distal radius: a registry analysis of 42,583 patients in Stockholm County, Sweden, 2004–2010. Acta Orthop. 2013; 84(3):292-6. PMC: 3715813. DOI: 10.3109/17453674.2013.792035. View

19.

Pater T, Grindel S, Schmeling G, Wang M . Stability of unicortical locked fixation versus bicortical non-locked fixation for forearm fractures. Bone Res. 2015; 2:14014. PMC: 4472129. DOI: 10.1038/boneres.2014.14. View

20.

Webber T, Patel S, Pensak M, Fajolu O, Rozental T, Wolf J . Correlation between distal radial cortical thickness and bone mineral density. J Hand Surg Am. 2015; 40(3):493-9. DOI: 10.1016/j.jhsa.2014.12.015. View