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Cables, Plates & Onlay Allografts

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

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Cables, Plates & Onlay Allografts

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  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 • 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. Symmetrical Wire twist wrap Square knot AO loop & tuck AO Loop Double loop Cables a – Stainless Steel wire Knot twist • 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 100000 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 (Ritter2006)

  7. Cables c - Nylon • Nylon core, UHMWPesheath (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

  9. Cables c - Nylon • Fatigue strength 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. Platesa- 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. Old 2006 Rx Platesa- 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. Platesb- 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. Platesb- Locking plates • C# & B1# • 100% union • LCP • MIPPO • 90% union • LCP • LISS technique difficult but fewer complications than traditional fixation • Better results IF combined with struts

  17. Sit in screw head Platesc- 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. PlatesScrew angles d D • DCP • Offset hole 4mm on broad BUT not narrow plate • 250 & 70 screw angle

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

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

  21. 570 160 PlatesScrew angles • DCP • Offset hole 4mm on broad BUT not narrow plate • 250& 70screw angle • LC-DCP • 800& 140screw angle, 4mm offset • Locking CP • 500 (<DCP) and 140 non locked screw angle, 4mm offset • Kinamed Supercable • 570 & 160 nonlocked screw angle, 4mm offset • Curved plates (match femur) 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 • Uncontained non-circumferential defects • As a ‘Plate’ • Reinforce bone loss areas & bypass stress risers • Fix periprosthetic fractures • Stabilize bulk allograft : host junctions

  26. Onlay AllograftTechnique • 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 diameter @ 90:90 anterior & lat • Preserves b.s from linea aspera & reduced stripping

  27. Onlay AllograftBiology 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 AllograftBiology 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 AllograftBio-mechanics • Bone strength • Freezing > freezing & irradiation > freeze drying • Dead bone > repaired bone (resorption)……… • Allograft fractures increase around 2-4 years • Stress shieldingin vitro • Plate > strut

  30. Onlay AllograftResults • Plate & strut better than strut alone • 90 - 95% 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 • 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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