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

When is the stability of a fracture fixation limited by osteoporotic bone?

Lukas Konstantinidis

, Peter Helwig

, Anja Hirschmüller

, Elia Langenmair

, Norbert P. Südkamp

, Peter Augat

Klinik für Orthopädie und Unfallchirurgie, Universitätsklinik Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany

Institut für Biomechanik, Berufsgenossenschaftliche Unfallklinik Murnau & Paracelsus Medical University, Salzburg, Prof. Kuentscher Str. 8, 82418 Murnau, Germany

A B S T R A C T

This article is concerned with the search for threshold values for bone quality beyond which the risk of fixation

failure increased. For trochanteric fractures we recognized a BMD lower than 250 mg/cm

as an additional risk for

cut out. For medial femoral neck fractures since joint replacement surgery is available and produces excellent

functional results, we see no indication for further differentiation or analysis of bone quality in relation to fracture

fixation. In the area of osteoporotic vertebral body fractures, there are many experimental studies that try to

identify BMD limits of screw fixation in the cancellous bone on the basis of QCT analysis. However, these values

have not yet been introduced for application in clinical practice. In case of indication for surgical fixation, we favor

minimally invasive, bisegmental, fourfold dorsal instrumentationwith screw-augmentation for a T-value less than

−

2.0 SD (DXA analysis, total hip or total lumbar spine). For proximal humerus fractures, BMD value of 95 mg/cm

could be seen as a threshold value below which the risk of failure rises markedly. In relation to osteoporotic distal

radius fractures, based on our clinical experience and scientific analyses there are virtually no restrictions as far as

bone quality is concerned on the application of palmar locking implants in the surgical management of distal

radius fractures. Optimization of preoperative diagnostics might help to revise the treatment algorithm to take

bone density into account, thus reducing the risk of failure and, at the same time, acquiring additional data for

future reference.

K E Y W O R D S

Fracture fixation

Osteoporotic bone

Stability

Failure

Introduction

Osteoporosis is a widespread disease process and is now not only

prevalent in Europe and north America but has become a worldwide

challenge [1] due to an increase in life expectancy. Orthopaedic

traumatology is particularly impacted by this phenomenon for two

reasons: firstly, fracture rates have increased markedly and, secondly,

fracture treatment of osteoporotic bones differs in several ways from

treatment of non-osteoporotic bones. Typical locations of osteoporotic

fractures include the proximal femur, proximal humerus, distal radius

and spine. Many fractures can be treated surgically or non-surgically so

a choice has to be made between these options with their associated

advantages and disadvantages. Ultimately, surgery may be unavoid-

able, especially for fractures of the lower extremities.

If the treatment of choice is surgical intervention, success depends

on three important parameters: Selection of the ideal implant,

best possible anatomical reduction, and correct positioning of the

implant [2]. Slight deficits in any one of these three areas can generally

be compensated for by non-osteoporotic bone during fracture healing.

However, twomain characteristics differentiate osteoporotic bone from

the healthy skeleton: firstly, implant anchorage (generally in trabecular

bone) tends to be insufficient [3], secondly, fracture healing takes longer

due to a decelerated bone metabolism [4]. These factors combined

repeatedly lead to fatigue failure that is manifest as screw migration

through cancellous bone (cut out [3]) with resultant dislocation of the

fracture and fixation failure, even when none of the three critical areas

show any relevant deficits. This article is concerned with the search for

thresholdvalues for bone qualityand/or bonedensitybeyondwhich the

stability of the osteosynthesis is limited and the risk of fixation failure

increased. Identifying threshold values will make it possible to modify

the treatment concept to accommodate individual bone quality and

predict complication risk more accurately, e.g. in relation to non-

surgical and surgical fracture treatment or joint replacement. The data

are based on published literature and derived from the author

’

s own

experimental findings and clinical experience.

Corresponding author: Prof.

Dr.

Peter Augat,

Institut für Biomechanik,

Berufsgenossenschaftliche Unfallklinik Murnau & Paracelsus Medical University, Salzburg,

Prof. Kuentscher Str. 8, 82418, Murnau, Germany.

E-mail address

biomechanik@bgu-murnau.de

Injury, Int. J. Care Injured 47S2 (2016) S27

–

S32

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