treatment of femoral neck fractures internal fixation –in biologic ‘young’ patients (<...

Treatment of femoral neck fractures

• INTERNAL FIXATION– In biologic ‘young’ patients (< 60-80 yr)

• ARTHROPLASTY – In biologic ‘old’ patients (> 60-80 yr)

Resultsof fixation of femoral neck fractures

35% RE-INTERVENTION RATE IN DISPLACED #• Non-union • Avascular necrosis • Loss of fixation

Fracture healingof femoral neck fractures

GOALS:• Preserve the remaining

blood supply• Provide the stability

necessary for revascularisation

• Provide the stability necessary for primary osteonal reconstruction

MEANS:• Anatomical reduction • Stable internal fixation

Why do implants fail?multiple parallel screws or pins:

PRO’S:• Dynamic• Minimal invasiveCON’S:• No angular stability• No rotational stability• Stability relies on the

three- point fixation method and is dependant on exact screw placement

• High total implant volume

Why do implants fail?sliding hip screw devices:

PRO’S:• Angular stability• DynamicCON’S:• No rotational stability

– During insertion – After insertion– With or without

‘anti-rotation’ screw• High implant volume

LABILE UNSTABLE

Can we make a better implant?

GANNET• Gannet nail & side wings• Impaction anchors• Gannet plate

CHARACTERISTICS:• Rotational stability• Angular stability• Dynamic compression• Impaction locking• Minimal invasive• High load bearing surface• Cannulated technique• Simple instrumentation

ROTATIONAL STABILITY:• Sidewings on blade• Impaction anchors

ANGULAR STABILITY:• Sliding barrel plate• Dynamic compression

IMPACTION LOCKING:Locking of the Gannet nail in the femoral head

1. Prevents perforation2. Prevents backing out3. Additional rotational stability4. Augmented by bone impaction

MINIMAL INVASIVELow implant volume:

• GANNET: 920 mm3

• DHS: 1975 mm3

MINIMAL INVASIVELow frontal area:• GANNET: 31 mm2

• DHS: 133 mm2

HIGH LOAD BEARING SURFACE:• GANNET: 338 mm2

• DHS: 221 mm2

CANNULATED:3.0 mm guide wire

SIMPLE INSTRUMENTATION

GANNET (DLBP)loading tests

GANNET (DLBP)static deformation test

ASTM F384-99 Static Loading Test

0

250

500

750

1000

1250

1500

1750

2000

2250

2500

2750

0 1 2 3 4 5 6 7 8 9 10 11

Displacement (mm)

Forc

e (N

)

DHS_57

DLBP_57_BioDur108

GANNETfatigue test

Fatigue testDLBP, Biodur 108, Size: 100mm, free length: 63 mm

0

200

400

600

800

1000

1200

1400

1600

0 250 500 750 1000 1250 1500 1750 2000

10^3 Cycles

Fo

rce

(N

)

GANNETanchor expansion test

GANNETpush in test

GANNET (DLBP)cut out test

GANNET (DLBP)rotation test

Guide pin insertion

Stepped cannulated drilling

Introducer setting

Introducer/implant assembly

One step insertion

GANNET pilot study

• No technical complications• No general complications• Fracture healing 23/25• Avascular necrosis 1/25• Non union 1/25

GANNET pilot study

REINTERVENTION RATE : 2/25• Undisplaced fractures (n=8) : 0/8• Displaced fractures (n=17) : 2/17

GANNET conclusions

• Fast• Streamlined• Targeted • Fold wings in

pursuit