Injury | International Journal of the Care of the Injured - Volume 47 - Supplement 2

Managing Vancouver B1 fractures by cerclage system compared to locking plate

fixation

–

a biomechanical study

Katharina Gordon

*, Martin Winkler

*, Thomas Hofstädter

, Ulrich Dorn

, Peter Augat

b,c

Department of Orthopedic Surgery, Salzburg General Hospital, Paracelsus Medical University, Müllner Hauptstr. 48, 5020 Salzburg, Austria

Institute of Biomechanics, Trauma Center Murnau, Prof. Küntscher-Str. 8, 82418 Murnau, Germany

Institute of Biomechanics, Paracelsus Medical University Salzburg, Strubergasse 21, 5020 Salzburg, Austria

A B S T R A C T

With increasing life expectancy and number of total hip arthroplasties (THA), the need for revision surgery is

increasing too. The aim of this study was to evaluate the optimal fracture treatment for a clinically characteristic

Vancouver B1 fracture. We hypothesized that locking plate fixation has biomechanical advantages over fixation

with a simple cerclage system. Additionally, we hypothesized that removal of the primary short stem and revision

with a long stem would show biomechanical benefit.

The biomechanical testing was performed with a static and a dynamic loading protocol on twenty 4th Generation

sawbones. These were divided into four different groups (

= 5 each). In group 1, the primary uncemented short

stem remained and the fracturewas stabilized with a locking plate. In group 2, the primary stem remained and the

fracture was stabilized with a cerclage stabilization system containing two stabilizers and four cerclages. In group

3, the primary stem was replaced by an uncemented long revision stem and the fracture was fixed with a locking

plate. In group 4, the short stemwas replaced by a long revision stem and the fracture was fixed with the cerclage

system.

Static testing revealed that the revision of the short stem with the long stem caused a 2-fold (

< 0.001, ANOVA)

increase of axial stiffness. In dynamic testing, the number of cycles to failurewas 4 times (

< 0.001, ANOVA) higher

with the long revision stem. Compared to locked plating cerclagewiring demonstrated a 26% more cycles to failure

(

= 0.031, ANOVA). The load to failure was 91% larger (

< 0.001, ANOVA) with the long revision stem and 11%

smaller with locked plating (

< 0.001, ANOVA).

In conclusion, the present biomechanical study indicates that periprosthetic Vancouver B1 fractures can be

sufficiently fixed by simple cerclage systems. Revision with a long replacement stem provides a superior

mechanical stability regardless of type of osteosynthesis fixation and is therefore a viable method in Vancouver B1

cases. A disadvantage of the cerclage system compared to plating is that an increased subsidence of the short stem

was observed.

K E Y W O R D S

Periprosthetic femoral fracture

Fracture fixation

Cerclage

Locking plate

Biomechanical study

Sawbone model

Revision surgery

Total hip arthroplasty

Complication

Introduction

With the increasing number of hip arthroplasties and the growth

in life expectancy, the need for revision surgery after periprosthetic

fractures is rising [1

–

3]. Additionally, a rise of intraoperative fractures

has been reported with the introduction of uncemented stems, often as

a consequence of the effort to obtain sufficient press fit. The incidence

for intraoperative fractures with cemented hips was described in 1992

by Kavanagh et al. as 0.1

–

1%, which is considerably lower than the

incidence for non-cemented hips of 5.4% [4].

Revision surgery can be challenging, particularly in osteoporotic

bone and with elderly patients, who require stable fixation and rely on

immediate weight bearing capacity of the revision. Although compli-

cations during revision surgery are rare, they result in severe morbidity

and mortality [2]. About 80% of all periprosthetic fractures represent

Vancouver B1 fractures [1] with a stable implant and a fracture line at

the tip of the prosthesis. Typically, the fracture is a spiral fracture,

extending over a large part of the prosthesis (Figure 1). In contrast,

biomechanical studies on periprosthetic fractures typically simulate

the fracture situation with a short transverse [5

–

8] or a short oblique

Corresponding author at: Katharina Gordon, Department of Orthopedic Surgery, Salzburg

General Hospital, Paracelsus Medical University, Müllner Hauptstraße 48, 5020 Salzburg,

Austria. Tel.: +43662448250090; Fax:

+435725550004

Corresponding author at: Institute of Biomechanics, Trauma Center Murnau, Prof.

Küntscher-Str. 8, 82418 Murnau, Germany. Tel.:

+498841482904;

Fax:

+498841484573

E-mail address

gordon@gordonmed.at

(K. Gordon);

Martin.Winkler@bgu-murnau.de

(M. Winkler)

Injury, Int. J. Care Injured 47S2 (2016) S51

–

S57

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