The biomechanics of plate fixation of periprosthetic femoral fractures near the tip of a total hip implant: cables, screws, or both?

Shah, Suraj; Kim, S Y R; Dubov, A; Schemitsch, Emil H.; Bougherara, Habiba; Zdero, Rad

doi:10.1177/0954411911413060

Cited by 59 publications

(77 citation statements)

References 40 publications

(105 reference statements)

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“…Bicortical screws were chosen to stabilize the screw-bone interface [6,7]. The generic locking plates and screws were modeled using stainless steel material properties (E = 193.0 GPa; m = 0.3; q = 8000 kg/m 3 ) [24]. Geometric properties of the sevenhole and nine-hole small-fragment locking plates and screws are similar to FDA-approved commercial hardware (Table 1).…”

Section: Methodsmentioning

confidence: 99%

Dual Plating of Humeral Shaft Fractures: Orthogonal Plates Biomechanically Outperform Side-by-Side Plates

Kosmopoulos

Nana

2014

Clinical Orthopaedics &Amp; Related Research

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Background Single large-fragment plate constructs currently are the norm for internal fixation of middiaphyseal humerus fractures. In cases where humeral size is limited, however, dual small-fragment locking plate constructs may serve as an alternative. The mechanical effects of different possible plate configurations around the humeral diaphysis may be important, but to our knowledge, have yet to be investigated. Questions/purposes We used finite element analysis to compare the simulated mechanical performance of five different dual small-fragment locking plate construct configurations for humeral middiaphyseal fracture fixation in terms of (1) stiffness, (2) stress shielding of bone, (3) hardware stresses, and (4) interfragmentary strain. Methods Middiaphyseal humeral fracture fixation was simulated using the finite element method. Three 90°and two side-by-side seven-hole and nine-hole small-fragment dual locking plate configurations were tested in compression, torsion, and combined loading. The configurations chosen are based on implantation using either a posterior or anterolateral approach. Results All three of the 90°configurations were more effective in restoring the intact compressive and torsional stiffness as compared with the side-by-side configurations, resulted in less stress shielding and stressed hardware, and showed interfragmentary strains between 5% to 10% in torsion and combined loading. Conclusions The nine-hole plate anterior and seven-hole plate lateral (90°apart) configuration provided the best fixation. Our findings show the mechanical importance of plate placement with relation to loading in dual-plate fracture-fixation constructs. Clinical Relevance The results presented provide novel biomechanical information for the orthopaedic surgeon considering different treatment options for middiaphyseal humeral fractures.

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Section: Methodsmentioning

confidence: 99%

Dual Plating of Humeral Shaft Fractures: Orthogonal Plates Biomechanically Outperform Side-by-Side Plates

Kosmopoulos

Nana

2014

Clinical Orthopaedics &Amp; Related Research

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“…More physiological orientation ranges from 7°to 25°of adduction during walking. [18][19][20][21][22][23][25][26][27]37 However, two previous studies used vertical femur alignment. 24,44 Moreover, the vertical force was parallel to the long axis of the femur-stem interface, thereby minimizing interfacial resistance to vertical compression.…”

Section: Potential Limitationsmentioning

confidence: 99%

“…Yet, synthetic femurs have practical advantages, 36 are being increasingly used in biomechanical studies, [18][19][20][21][22][23][25][26][27]37 have similar stiffness and screw pullout stress compared to human femurs, [37][38][39][40] and show clinically realistic failure mechanisms in axial compression. 23 Even so, the extrapolations made from current results should be considered preliminary until a more definitive biomechanical study is done on these press-fit stems while inserted into human femurs.…”

Section: Potential Limitationsmentioning

confidence: 99%

“…24 Stiffness and strength were measured currently because they are very common parameters for in vitro biomechanical studies on bone-implant constructs. [18][19][20][21][22][24][25][26][27][28] They are performed to assess the global properties of bone-implant constructs immediately postoperatively. Specifically, stiffness is useful in understanding boneimplant behavior during low loads, say, during common physician-prescribed precautionary 'toe touch' weight-bearing immediately following orthopedic surgery.…”

Section: Overall Testing Strategymentioning

confidence: 99%

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A biomechanical comparison of four different cementless press-fit stems used in revision surgery for total knee replacements

Zdero

Saidi

Mason

et al. 2012

Proc Inst Mech Eng H

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Few biomechanical studies exist on femoral cementless press-fit stems for revision total knee replacement (TKR) surgeries. The aim of this study was to compare the mechanical quality of the femur–stem interface for a series of commercially available press-fit stems, because this interface may be a ‘weak link’ which could fail earlier than the femur–TKR bond itself. Also, the femur–stem interface may become particularly critical if distal femur bone degeneration, which may necessitate or follow revision TKR, ever weakens the femur–TKR bond itself. The authors implanted five synthetic femurs each with a Sigma Short Stem (SSS), Sigma Long Stem (SLS), Genesis II Short Stem (GSS), or Genesis II Long Stem (GLS). Axial stiffness, lateral stiffness, ‘offset load’ torsional stiffness, and ‘offset load’ torsional strength were measured with a mechanical testing system using displacement control. Axial (range = 1047–1461 N/mm, p = 0.106), lateral (range = 415–462 N/mm, p = 0.297), and torsional (range = 115–139 N/mm, p > 0.055) stiffnesses were not different between groups. The SSS had higher torsional strength (863 N) than the other stems (range = 167–197 N, p < 0.001). Torsional failure occurred by femoral ‘spin’ around the stem’s long axis. There was poor linear correlation between the femur–stem interface area versus axial stiffness (R = 0.38) and torsional stiffness (R = 0.38), and there was a moderate linear correlation versus torsional strength (R = 0.55). Yet, there was a high inverse linear correlation between interfacial surface area versus lateral stiffness (R = 0.79), although this did not result in a statistical difference between stem groups (p = 0.297). These press-fit stems provide equivalent stability, except that the SSS has greater torsional strength.

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“…Furthermore, no optimal fixation method has yet been established and there has been limited biomechanical or clinical data comparing various methods of screw and cable attachment [16,17].…”

Section: Introductionmentioning

confidence: 99%

Periprosthetic femoral fracture fixation: A biomechanical comparison between proximal locking screws and cables

Graham

Mak

Moazen

et al. 2015

Journal of Orthopaedic Science

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Background: The incidence of periprosthetic femoral fractures (PFF) around a stable stem is increasing. The aim of this biomechanical study is to examine how three different methods of fixation, for Vancouver type B1 PFF, alter the stiffness and strain of a construct under various configurations in order to gain a better insight into the optimal fixation method. Methods:Three different combinations of proximal screws and Dall-Miles cables were used: (A) proximal unicortical locking screws alone; (B) proximal cables and unicortical locking screws; (C) proximal cable alone, each in combination with distal bicortical locking screws, to fix a stainless steel locking compression plate to five synthetic femora with simulated Vancouver type B1 PFFs. In one synthetic femora there was a 10mm fracture gap, in order to simulate a comminuted injury. The other four femora had no fracture gap, to simulate a stable injury. An axial load was applied to the constructs, at varying degrees of adduction and the overall construct stiffness and surface strain were measured.Results: With regards to the stiffness, in both the gap and no gap models, method of fixation A was the stiffest form of fixation. The inclusion of the fracture gap reduced the stiffness of the construct quite considerably for all methods of fixation. The strain, across both the femur and the plate, was considerably less for method of fixation C, compared to A and B at the locations considered in this study. Conclusion:This study highlights that the inclusion of cables appears to damage the screw fixations and does not aid in the construct stability. Furthermore, the degree of fracture reduction affects the whole construct stability and the bending behaviour of the fixation.

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The biomechanics of plate fixation of periprosthetic femoral fractures near the tip of a total hip implant: cables, screws, or both?

Cited by 59 publications

References 40 publications

Dual Plating of Humeral Shaft Fractures: Orthogonal Plates Biomechanically Outperform Side-by-Side Plates

Dual Plating of Humeral Shaft Fractures: Orthogonal Plates Biomechanically Outperform Side-by-Side Plates

A biomechanical comparison of four different cementless press-fit stems used in revision surgery for total knee replacements

Periprosthetic femoral fracture fixation: A biomechanical comparison between proximal locking screws and cables

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