1. Cables, Plates & Onlay Allografts
Mark Ashworth
Torbay Hospital

2. Cables, Plates & Onlay Allografts
Guide you through the ‘menu’
Discuss the merits of the various ‘dishes’
Perhaps make a recommendation or two
Set the scene for the ‘main course’ to follow

3. Cables

4. Cables Current indications Contra-indications Prophylactically
Increased hoop stress resistance (Tsiridis, 2003)
Temporary
Stabilisation pending plate, strut, THR insertion
Definitive
Simple periprosthetic # - alone
Calcar splits on insertion
B1 spiral #
Complex periprosthetic # - with other devices
Plates, mesh, impaction or strut graft….
Contra-indications
Transverse/short oblique periprosthetic #
(poor torsion/bending rigidity)

5. Cables a – Stainless Steel wire
Knot twist
AO Loop
Double loop
Square knot AO loop & tuck
Symmetrical Wire
twist wrap
Knot Strength
Thicker wire = stronger knots (Wilson 1985)
>2 twists = NO increase in strength (Schultz 1985)
Double loop knot strength > square knot > twist (Roe, 1997 & 2002)
Simple twist easily untwists with little tension (Meyer 2003)
Knot twist cycle fatigue stronger>twist (Bostrom 1994)

6. Cables b - Multi filament
Cable material
Zimmer & Biomet - Stainless steel, cobalt chrome & titanium
De puy - Stainless steel 1.8mm
Dall Miles - Stainless steel & Cr Co Mo (vitallium)
Cable strength
Fatigue – cables superior to SS wire (Weiss 1996)
Ultimate strength – 1 cable > 1 wire (Carls 1997); but 1 cable = 2 wires (Liu 1997)
Chrome cobalt > stainless steel
Cable cost
Double loop cerclage ~10x less £££££ than cables (Ritter 2006)

7. Cables c - Nylon
Nylon core, UHMWPe sheath (Ti/Al/V clasp - some Cr Co)
Contraindication if can catch on mesh or plate edge (Kinamed)
Elastic energy stored after initial relaxation
Iso-elastic cable maintains continuous compressive forces = initial compression of cerclage wires
Compensates for # movement & decreased risk of cable slip

8. Cables c - Nylon Ultimate strength Cerclage Type
Ultimate Tensile Strength
Nylon SuperCable
1000N
Stainless steel wire N
Titanium alloy cable N
Cobalt-chrome alloy cable N

9. Cables c - Nylon Fatigue strength Cerclage Type Cyclic Load
Cycles to Failure
Nylon SuperCable
400N
No 1 million cycles
Stainless steel wire N
100,000 cycles
Titanium alloy cable
40 – 200 N
100,000 – 1 million cycles
Cobalt-chrome alloy cable
80 – 200 N
Breakage in cabling systems are generally fatigue failure not tensile failures

10. Plates

11. Plates “2B or not 2B, that is the question”
Lindahl 2006 Swedish register 245 cases-
Single plate ORIF higher risk of failure with B1#
#’s were probably un-recognised B2 (revision best)
Prosthesis considered loose until proven otherwise
Infer…..’ no place for fixing #, then later revising stem ‘

12. Plates
Non locked
Locked
Cable plate systems
Dall Miles 1983

13. Plates a- Non Locking plates
Ogden (1978) - Proximal cables, distal screws
Plate & screws (in vitro) > Ogden > 2 struts > cabled plate
Clinical results = 80% good/union
Standard plate - All Screws
90 : 90 plating = best biomechanics
Soft tissue strip++
90% union with broad DCP

14. Plates a- Non Locking plates
Old 2006 Rx
Plates a- Non Locking plates
Old 2006
95 % union ( no bone graft/strut)
Long plate for proximal screw fixation
+/- cerclage wires
Their technique = Haddad 2002 results
used strut allograft or strut & plate
MIPPO B1 #
Indirect ORIF 1 lateral plate no bone graft
~12/52 86% union
100% (Abhaykumar 2000, Ricci 2005)
Adjuvant bone graft not always necessary (Ricci 2007)

15. Plates b- Locking plates
Stiffer than Ogden, & fail by lat cortex fracture (Fulkerson 2006)
Conventional outermost screw reduces stress riser & significantly increased strength (Bottlang 2009)
90:90 construct (plate or strut) (Talbot 2008)
Stiffer than 1 plate
Locking screws give no mechanical advantage over conventional screws
No cable loosening after 100,000 cycles

16. Plates b- Locking plates
C# & B1#
100% union
LCP
MIPPO
90% union
LISS technique difficult but fewer complications than traditional fixation
Better results IF combined with struts

17. Plates c- Cable plates B1 # Avoid if retaining a stem in varus
Sit in screw head
Plates c- Cable plates
B1 #
100% union 4/12
85% union
57% union, cabled Dall Miles – ‘consider strut or long stem’
40% successful union, ‘avoid in varus stem’
Avoid if retaining a stem in varus
Threaded pin cerclage better than cerclage plate wrap

18. Plates Screw angles D DCP d
Offset hole 4mm on broad BUT not narrow plate
250 & 70 screw angle

19. Plates Screw angles D DCP LC-DCP
Offset hole 4mm on broad BUT not narrow plate
250 & 70 screw angle
LC-DCP
800 & 140 screw angle, 4mm offset D

20. Plates Screw angles DCP LC-DCP Locking CP
Offset hole 4mm on broad BUT not narrow plate
250 & 70 screw angle
LC-DCP
800 & 140 screw angle, 4mm offset
Locking CP
500 (<DCP) and 140 non locked screw angle
4mm offset

21. Plates Screw angles DCP LC-DCP Locking CP Kinamed Supercable
Offset hole 4mm on broad BUT not narrow plate
250 & 70 screw angle
LC-DCP
800 & 140 screw angle, 4mm offset
Locking CP
500 (<DCP) and 140 non locked screw angle, 4mm offset
Kinamed Supercable
570 & 160 non locked screw angle, 4mm offset
Curved plates (match femur)
160
570 D+

22. Plates
Mennen

23. Plates Mennen Ahuja 2002 75% complication rate
Noorda 2002 mechanical failure 31% and non-union 28%

24. Onlay Allograft

25. Onlay Allograft Current indications Restore bone loss As a ‘Plate’
Uncontained non-circumferential defects
As a ‘Plate’
Reinforce bone loss areas & bypass stress risers
Fix periprosthetic fractures
Stabilize bulk allograft : host junctions

26. Onlay Allograft Technique
1st description
Penenberg & Chandler 1989
Chandler 1998
Struts ½ diameter of shaft
Med & lat placement, contour to fit shaft
To avoid stress riser plate/allograft should be staggered & bypass # by 2 diameters
Avoid linea aspera to protect blood supply
Keep periosteum for blood supply
Cables x 6 minimum
Bradey 1999
1/3 90:90 anterior & lat
Preserves b.s from linea aspera & reduced stripping

27. Onlay Allograft Biology of union
Bone resorption
Variable rounding off & scalloping by 6 months
Bridging
Partial at 8/12 , completed by 1 yr
Partial revascularisation
20% by 5 years
Diffuse loss of radiodensity & changed trabecular pattern
Remodelling
Of the graft & host femur

28. Onlay Allograft Biology of union
Union rate
Improves if rigid fixation
11-20% fail -infection, rejection, fracture, non union
Union speed/quality
Auto graft better quality union but not faster
Osteogenic protein 1 - faster healing & better quality
BMP faster healing & better quality
Immune response
Reduces osteoinduction
Freezing reduces antigenicity

29. Onlay Allograft Bio-mechanics
Bone strength
Freezing > freezing & irradiation > freeze drying
Dead bone > repaired bone (resorption)………
Allograft fractures increase around 2-4 years
Stress shielding in vitro
Plate > strut

30. Onlay Allograft Results
Plate & strut better than strut alone
% union, strut alone
95% union, 1 plate 1 strut
98% union, struts +/- plate

31. My Recommendations:-

32. My Recommendations:- Wire
Temporary use – thickness & knot type is unimportant
Definitive use – if run out of cables simple B1 or C# (with great caution)

33. My Recommendations:- Wire Cables
Temporary use – thickness & knot type is unimportant
Definitive use – if run out of cables simple B1 or C# (with great caution)
Cables
MUCH better than wire, but best used with plates
Nylon cables have some theoretical advantages in more complex # pattern
movement compensation; but costs more

34. My Recommendations:- Wire Cables Plates
Temporary use – thickness & knot type is unimportant
Definitive use – if run out of cables simple B1 or C# (with great caution)
Cables
MUCH better than wire, but best used with plates
Nylon cables have some theoretical advantages in more complex # pattern
movement compensation; but costs more
Plates
Cabled plates good enough
Broad plates with all screws (offset screw holes) are better
Locked plates best
MIPPO difficult but results worth the effort

35. My Recommendations:- Wire Cables Plates Strut graft
Temporary use – thickness & knot type is unimportant
Definitive use – if run out of cables simple B1 or C# (with great caution)
Cables
MUCH better than wire, but best used with plates
Nylon cables have some theoretical advantages in more complex # pattern
movement compensation; but costs more
Plates
Cabled plates good enough
Broad plates with all screws (offset screw holes) are better
Locked plates best
MIPPO difficult but results worth the effort
Strut graft
Almost as good as locked plates clinically

36. My Recommendations:- Wire Cables Plates Strut graft
Temporary use – thickness & knot type is unimportant
Definitive use – if run out of cables simple B1 or C# (with great caution)
Cables
MUCH better than wire, but best used with plates
Nylon cables have some theoretical advantages in more complex # pattern
movement compensation; but costs more
Plates
Cabled plates good enough
Broad plates with all screws (offset screw holes) are better
Locked plates best
MIPPO difficult but results worth the effort
Strut graft
Almost as good as locked plates clinically
90:90 configuration, although stronger bio-mechanically, clinically probably not necessary.

37. Thank You