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Periprosthetic Fx of the femur complicating Total Knee Arthroplasty

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Title: Periprosthetic Fx of the femur complicating Total Knee Arthroplasty


1
Periprosthetic Fx of the femur complicating Total
Knee Arthroplasty
  • C. Rorabeck, M.D.
  • Reviewed by K. Ikram, D.O.
  • June 20, 2000

2
Introduction
  • Periprosthetic fx are increasing as the number of
    TKA increases
  • Present a significant challenge to orthopedic
    surg
  • Difficulty in management relates to 3 major
    issues
  • Fx pattern itself
  • Surrounding bone may be osteopenic
  • Fixation of the prosthesis
  • Currently no clear consensus for best tx of these
    fx

3
  • Some support non-op tx
  • Several support op tx
  • With either, complication rates continue to be
    significant and are reported as high as 25-75.

4
Classification
  • Proposed by Lewis and Rorabeck
  • Considers 3 variables
  • Location of fx
  • Quality of bone
  • Stability of the prosthesis
  • Based on classification bone quality, algorithm
    proposed.

5
  • Tx algorithm for supracondylar periprosthetic fx

6
Intraoperative fx
  • Intraop fx may occur during primary or revision
    TKA
  • Frequently involve femoral or tibial condyles
  • May fx fem or tibial shaft in revision TKA

7
Condylar fractures
  • Most common fx that occurs in assoc. with primary
    TKA
  • Assoc. with post. stabilized implant
  • Occurs if surgeon inadvertently medialized or
    lateralizes fem box cut for the post stabilized
    peg
  • Medial condyle most commonly involved
  • Also, may have overvigorous impaction of the fem
    component onto the condyles

8
  • Condylar fx should be exposed extensively and the
    prox extent of the fx visualized
  • Intraop x-rays should be obtained
  • Isolated condylar fx can usually be tx with a
    simple lag screw
  • A stemmed fem or tibial implant should be used to
    offload the condylar fx

9
Femoral shaft fractures
  • Occur during insertion of intramed alignment
    guide rod or with excessively vigorous reaming of
    med canal at time of primary or revision
    arthroplasty
  • Increased risk in pts with osteoporosis or with
    pts with deformed femurs
  • Full length x-rays of femur and tibia should be
    performed pre-operatively
  • Most common location is ant cortex, at level of
    ant bow of femur

10
  • Revision femoral comp that use stems gt 190 mm are
    likely to impinge on ant bow of femur
  • If stem of gt 190 mm needed, stem should be curved
  • If fx occurs intra-op, obtain intra-op x-rays and
    place longer stem
  • Stem should extend at least 2 shaft diameters
    beyond the fx site.
  • If noted on post op films, must decide if return
    to OR or use prolonged protected wt bearing.

11
  • If ant cortex has been broached without
    structural damage to remainder of fem or tibia
    tube, manage non-op.
  • If fx at level of tip of stem, fx should be
    re-explored and either plate and screw or longer
    stem implant placed
  • If replacing implant, augment fx site with a
    cortical strut graft and circlage wires.

12
Femoral Neck Fx
  • Rare complication of TKA
  • Can be assoc with osteopenic bone or with
    rheumatoid arthritis
  • Assoc with violent impaction of the fem component

13
Post operative fractures
  • Most frequently encountered fracture occurring
    after TKA is a supracondylar femur fracture

14
Supracondylar fractures
  • Often a devastating complication of TKA
  • Incidence ranges from 0.3-2.5
  • Most cases, trauma is relatively minor and fx is
    of low-energy type
  • Predisposing factors include
  • Osteoporosis
  • Rheumatoid arthritis
  • Corticosteroid us
  • Increase age
  • Female sex

15
  • Other factors include
  • Seizure disorder
  • Cerebral ataxia
  • Parkinsons disease
  • Myasthenia gravis
  • Cerebral palsy
  • Poliomyelitis
  • Neuropathic arthropathy
  • Cervical myelopathy

16
  • Local factors include
  • Bone loss resulting from osteolysis and implant
    loosening
  • Notching of the ant fem cortex caused by
    incorrect placement of fem component during
    primary TKA

17
Treatment
  • Based upon
  • Quality of bone
  • Location of fracture
  • Status of the prosthesis
  • If prosthesis failing, revise the prosthesis
  • Concomitant med conditions
  • Osteoporosis
  • Prefracture mobility
  • Historically, standard tx was non-op

18
  • Now trend is for operative intervention
  • Aim of surgical tx is achieve stability of fx
    sufficient to allow union with restoration of
    motion of the knee
  • Good result is defined as a pain-free joint with
    a healed fx and at least 90o ROM.
  • Shortening of 2 cm can be accepted, and 5o
    varus/valgus, or 10o of sagittal malalignment

19
Non operative treatment
  • Only indication for non-operative tx is an
    elderly pt with a stable fx pattern without
    displacement and a well-fixed component
  • If selected, knee should be immobilized in
    extension for 4-6 wks and pt be non wt bearing
  • Results of this are generally poor

20
Operative treatment
  • Method of choice for periprosthetic supracondylar
    femur fx
  • Objective is achieve union, mobilization of pt,
    and maintenance of ROM
  • Fx reduction and stabilization indicated if fx is
    displaced and prosthesis is stable
  • Is prosthesis is loose, revision of prosthesis
    with or without supplemental bone graft or
    allograft

21
  • Fixation with supracondylar buttress plate or
    supracondylar blade plate have been recommended
    in the past.
  • Often assoc with long-term failure largely b/c of
    inability to maintain reduction while fx is
    healing.
  • Success often precluded by quality of bone
  • Also has extensive soft tissue stripping
  • Some authors support cement augmentation or
    impaction of bone grafting to osteopenic condylar
    bone to improve screw fixation

22
  • Multiple studies have been performed
  • McLaren reviewed 223 cases with 56.9
    satisfactory results with closed methods and
    66.7 with open red
  • Chen reviewed 195 cases
  • 83 satisfactory results in non-op tx of
    non-displaced fx
  • 61 67 results for non-op vs op results of
    displaced fx
  • Recommended op tx if pts not able to tolerate
    long periods of bed rest, bone quality is
    sufficient, surgeon is able to perform procedure,
    pt has multiple fx, acceptable aligment no
    achieved closed, risk of infection is not high
  • Figgie reported on 24 pts, 10 tx non-op, only 9
    achieved union at 4 months

23
  • In an attempt to improve the fixation,
    intramedullar devices have been proposed
    including Rush pins, Zickel devices,
    intramedullary nails, and supracondylar nails.
  • Advantages include fx able to be reduced and
    stabilized with minimal soft tissue stripping
  • Sufficient stability can be achieved to provide
    early ROM of knee and protected mobilization
  • Disadvantages include loss of fixation, nonunion,
    and deep infection

24
  • Cant use in post stabilized knees with a closed
    fem box or in some cruciate-retaining fem
    components in which the trochlear girdle extends
    well posteriorly.
  • Intercondylar space is often narrow
  • Unusual to insert a nail in excess of 14 mm, not
    enough rigid fixation if osteoporotic bone.

25
Rush nails
  • Described by Ritter
  • Studied 22 pts
  • 2 Rush nails inserted thru each epicondyle to
    stabilize fractures after closed reduction
  • All fractures healed with two malunions and no
    other complications

26
Zickel nails
  • Has been suggested but no reports are in the
    literature
  • Use of Zickel nails reported in supracondylar fx
    of the femur in the absence of joint replacement
  • Marks reported on 33 elderly, all tx with a cast
    brace post op
  • All achieved union by 12 wks, apart from 6 who
    died
  • No infections or nonunions

27
Intramedullary nails
  • Rolston first reported on 4 supracondylar fx tx
    with supracondylar nails.
  • All fx united at an average of 11.5 wks, no
    complications
  • Recommended hinged brace and limited wt bearing
    for the first 6-8 wks
  • McLaren tx 7 cases
  • Distal in all cases
  • 6 had osteopenia from rheumatoid and steroid use
  • Stable fixation in all to achieve early ROM
  • Described technique of leaving nail proud by 1 cm
    to allow optimal locking screw positioning then
    using a high-speed burr to remove the prominent
    nail.

28
Loose implants
  • If implant loose, none of the aforementioned
    techniques appropriate
  • Revision of arthroplasty is method of choice
    incorporating long stems and allograft bone.
  • In addn to removing fem comp, normally necessary
    to excise the remaining distal fem condyles
  • Simpler to excise fem comp along with the
    fragments of bone
  • Distal fem allograft then prepared on back table
  • Step cut in host host femur and matched to
    appropriate step cut in allograft
  • Long stemmed prosthesis used to secure
    graft-prosthesis composite.
  • Use cerclage wire with or without strut
    allografts at butt jt

29
  • In Chens study of 195 supracondylar fx, 11 were
    tx by revision of prosthesis.
  • Satisfactory results in 10
  • McLarens study of 224 pts, 25 had revision of
    prosthesis with 24 having satisfactory results
  • Engh and Ammeen outlined their approach to a
    supracondylar fx adjacent to a loose or failing
    TKA

30
  • Recommend early revision of fem comp is best
    option for the tx of most type III fx
  • May also tx initially with internal fixation then
    revision of prosthesis at a later date
  • Advantage of delayed revision is that revision
    could be expected to be easier once the fx healed
  • Therefore, a standard revisionimplant can be used
    without the need for a large structural allograft
    or tumor prosthesis

31
Complications
  • Significant risk of complications regardless of
    the method of tx
  • Chen noted a complication rate of 30 tx either
    way
  • Nonunion occurred in 16 nonop, 12 with ORIF
  • Malunion more common in non op tx cases
  • Infection occurs in 8, may be lead to amputation
    or even loss of life

32
Conclusion
  • Periprosthetic fem fx after TKA pose a
    significant challenge to the orthopedic surgeon
  • Many factors must be considered for tx including
  • Fx pattern and location
  • Quality of surrounding bone
  • Fixation and performance of prosthesis
  • Patient factors
  • Fx of fem condyles that occur introp are fully
    exposed and tx with lag screw fixation with the
    addn of a stemmed comp

33
  • Fem shaft fx recognized intraop tx by bypassing
    the fx site with a long-stemmed prosthesis
  • Post op fx usually occur in supracondylar region
  • Most should be tx with internal fixation
  • Undisplaced or minimally displaced tx non op if
    fx stable early placement in hinged cast brace
    and mobilization with protected wt bearing are
    favored
  • Displaced fx tx with ORIF if prosthesis stable
  • Authors prefer supracondylar nails locked prox
    distal
  • Plate fixation used if prosthesis in place that
    makes insertion of nail impossible

34
  • If prosthesis is loose, must revise implant with
    a long stemmed implant
  • Complications are frequent and may lead to a
    devastating outcome.
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