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

Periprosthetic fracture fixation in osteoporotic bone

Mark Lenz

*, Wolfgang Lehmann

, Dirk Wähnert

Department of Trauma, Hand and Reconstructive Surgery, University Hospital Jena, Jena, Germany

Department of Trauma Surgery, Orthopaedics and Plastic Surgery, University of Göttingen Medical School, Göttingen, Germany

Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Münster, Germany

A B S T R A C T

Fixation techniques of periprosthetic fractures are far from ideal although the number of this entity is rising. The

presence of an intramedullary implant generates its own fracture characteristics since stiffness is altered along the

bone shaft and certain implant combinations affect load resistance of the bone. Influencing factors are cement

fixation of the implant, intramedullary locking and extramedullary or intramedullary localization of the implant

and the cortical thickness of the surrounding bone. Cerclage wires are ideally suited to fix radially displaced

fragments around an intramedullary implant but they are susceptible to axial and torsional load. Screws should be

added if these forces have to be neutralized. Stability of the screw fixation itself can be enhanced by embracement

configuration around the intramedullary implant. Poor bone stock quality, often being present in metaphyseal

areas limits screw fixation. Cement augmentation is an attractive option in this field to enhance screw purchase.

K E Y W O R D S

Periprosthetic fracture

Interprosthetic fracture

Nail

Plate

Cement augmentation

Introduction

Since arthroplasty numbers are rising, the periprosthetic fracture

fixation becomes more and more a concern [1]. Patient

’

s condition and

postoperative requirements render the treatment challenging. A high

primary stability is needed due to the fact that partial weight bearing

is impossible for many patients. Undiagnosed loosened prosthesis

stems, being considered as stable during surgery contribute to the

high failure rate actually reported for periprosthetic fracture osteo-

syntheses [2].

The main fixation techniques currently applied comprise revision

surgery with conversion to a longer non-cemented prosthesis stem

bridging the fracture zone, plate osteosynthesis and intramedullary

nailing.

Although the choice of the fixation method is still individualized

depending on the patient

’

s condition and the surgeon

’

s selection,

certain biomechanical principles could be deducted from recent

biomechanical studies. Varying fracture gap configurations fixed

with different plate types and screw configurations have been widely

investigated [3

–

6]. Vice versa, the type of implants and their

configuration additionally affect fixation stability [7]. Apart from the

working length of the implant, additional factors have to be taken into

account, since intramedullary and extramedullary implants are both

interacting in a fixed periprosthetic fracture [8]. Interprosthetic

fractures, sometimes requiring a fixation in-between two prosthesis

stems represent a separate category [9].

Osteoporotic bone quality is a special concern in metaphyseal

fracture locations like periprosthetic fractures of the distal femur at

non-constrained bicondylar total knee arthroplasties [10]. Screw

purchase in this almost cancellous bone area is limited. Implant

augmentation is an option to enhance fracture fixation [11].

Current mechanical aspects of periprosthetic fracture fixation are

summarized in this article, focusing on implant mechanics and their

affection of bone strength as well as the use of augmentation in

periprosthetic fracture fixation at the distal femur.

Biomechanics of periprosthetic fracture fixation

Bone quality, stability of the stem anchorage and fracture pattern

have direct impact on periprosthetic fracture fixation strategy.

Periprosthetic fractures with intact stem anchorage are the domain

of osteosynthesis. They are often located around the tip of the stem

where the bending stiffness drops, since the bone is not splinted by the

prosthesis stem any more. Simple fractures with closed fracture gap

and medial cortical support allow partial load transfer via the cortex. In

open fracture gap situations like comminuted fractures without medial

cortical support a single lateral plate might not be stable enough for

weight bearing and a stiffer plate or a double plating construct has to be

Corresponding author: Mark Lenz, MD Department of Trauma, Hand and Reconstructive

Surgery, University Hospital Jena, Erlanger Allee 101, D-07747 Jena, Germany. Tel.: +49 3641 9

322801; Fax: +49 3641 9 322802.

E-mail address:

mark.lenz@med.uni-jena.de

(M. Lenz).

Injury, Int. J. Care Injured 47S2 (2016) S44

–

S50

Contents lists available at ScienceDirect

Injury

journal homepage: www.

elsevier.com/locate/Injury