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Cables, Plates & Onlay Allografts Mark Ashworth Torbay Hospital.

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Presentation on theme: "Cables, Plates & Onlay Allografts Mark Ashworth Torbay Hospital."— Presentation transcript:

1 Cables, Plates & Onlay Allografts Mark Ashworth Torbay Hospital

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

3 Cables

4 Cables Current 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 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 –Knot twist cycle fatigue stronger>twist (Bostrom 1994) Knot twist AO Loop Double loop Square knot AO loop & tuck Symmetrical Wire twist wrap

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 Breakage in cabling systems are generally fatigue failure not tensile failures 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 100,000 – 1 million cycles

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 a. Non locked b. Locked c. 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 – –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 ) Old 2006 Rx

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 LCP LISS technique difficult but fewer complications than traditional fixation –Better –Better results IF combined with struts

17 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 Sit in screw head

18 Plates Screw angles DCP DCP –Offset hole 4mm on broad BUT not narrow plate –25 0 & 7 0 screw angle D d

19 Plates Screw angles DCP DCP –Offset hole 4mm on broad BUT not narrow plate –25 0 & 7 0 screw angle LC-DCP LC-DCP –80 0 & 14 0 screw angle, 4mm offset D

20 Plates Screw angles DCP DCP –Offset hole 4mm on broad BUT not narrow plate –25 0 & 7 0 screw angle LC-DCP LC-DCP –80 0 & 14 0 screw angle, 4mm offset Locking CP Locking CP –50 0 (

21 Plates Screw angles DCP DCP –Offset hole 4mm on broad BUT not narrow plate –25 0 & 7 0 screw angle LC-DCP LC-DCP –80 0 & 14 0 screw angle, 4mm offset Locking CP Locking CP –50 0 (

22 Plates Mennen Mennen

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

24 Onlay Allograft

25 Current indications – –Restore bone loss 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 – –BMP2 - 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 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 – –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 – –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 – –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 – –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


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