Periprosthetic Fx of the femur complicating Total Knee Arthroplasty

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Periprosthetic Fx of the femur complicating Total
Knee Arthroplasty

• C. Rorabeck, M.D.
• Reviewed by K. Ikram, D.O.
• June 20, 2000

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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

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• 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.

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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.

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• Tx algorithm for supracondylar periprosthetic fx

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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

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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

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• 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

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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

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• 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.

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• 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.

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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

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Post operative fractures

• Most frequently encountered fracture occurring
  after TKA is a supracondylar femur fracture

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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

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

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• 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

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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

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• 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

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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

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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

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• 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

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• 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

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• 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

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• 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.

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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

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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

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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.

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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

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• 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

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• 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

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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

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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

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• 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

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