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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

Cables, Plates & Onlay Allografts

Mark Ashworth

Torbay Hospital

cables plates onlay allografts1
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
cables1
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)

cables a stainless steel wire

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)
cables b multi filament
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)
slide7

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
slide8

Cables c - Nylon

  • Ultimate strength
slide9

Cables c - Nylon

  • Fatigue strength

Breakage in cabling systems are generally fatigue failure not tensile failures

plates1
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 ‘
plates2
Plates
  • Non locked
  • Locked
  • Cable plate systems
    • Dall Miles 1983
plates a non locking plates
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
plates a non locking plates1

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)
plates b locking plates
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
plates b locking plates1
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
plates c cable plates

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
plates screw angles
PlatesScrew angles

d

D

  • DCP
    • Offset hole 4mm on broad BUT not narrow plate
    • 250 & 70 screw angle
plates screw angles1
PlatesScrew angles
  • DCP
    • Offset hole 4mm on broad BUT not narrow plate
    • 250& 70screw angle
  • LC-DCP
    • 800 & 140 screw angle, 4mm offset

D

plates screw angles2
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
plates screw angles3

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+

plates3
Plates
  • Mennen
plates4
Plates
  • Mennen
    • Ahuja 2002 75% complication rate
    • Noorda 2002 mechanical failure 31% and non-union 28%
onlay allograft1
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
onlay allograft technique
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
onlay allograft biology of union
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
onlay allograft biology of union1
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
onlay allograft bio mechanics
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
onlay allograft results
Onlay AllograftResults
  • Plate & strut better than strut alone
    • 90 - 95% union, strut alone
    • 95% union, 1 plate 1 strut
    • 98% union, struts +/- plate
my recommendations1
My Recommendations:-
  • Wire
    • Temporary use – thickness & knot type is unimportant
    • Definitive use – if run out of cables simple B1 or C# (with great caution)
my recommendations2
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
my recommendations3
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
my recommendations4
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
my recommendations5
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.