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2. JAAOS Summaries (2016-2019) > Hip Arthroplasty (Complete) > Flashcards

Hip Arthroplasty (Complete) Flashcards

1
Q

What are the approaches to the hip?

[Can J Surg. 2015 Apr;58(2):128-39.]

A
  1. Anterior approach (Smith-Peterson)
  • Superficial plane – TFL and sartorius
  • Deep plane – rectus femoris and gluteus medius
  • Incision – 2cm lateral to ASIS, ~10cm
  • Structures at risk:
    • LFCN – take it medially
    • Ascending branch of the lateral femoral circumflex artery
  • Potential advantages:
    • Reduced blood loss
    • Earlier functional recovery
    • Low dislocation rates
    • Shorter stays in hospital
  1. Anterolateral approach (Watson-Jones)
    * Plane – TFL and gluteus medius
  2. Direct lateral approach (Hardinge)
  • Plane – split of gluteus medius and vastus lateralis
  • Structures at risk:
    • Superior gluteal nerve (~5cm proximal to GT)
    • Femoral nerve
  1. Posterior approach (Moore or Southern [Kocher-Langenbeck for trauma])
  • Plane – split of gluteus maximus
  • Incision – starts 5cm distal to tip of GT centered on femoral shaft curving 6cm proximal to GT towards PSIS
  • Structures at risk
    • Sciatic nerve
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2
Q

What is the Dorr classification of femoral bone quality?

A
  1. Determined by the canal/calcar isthmus ratio
    * Endosteal width 10cm below LT / endosteal width at mid-LT
  2. Type A
  • CC ratio <0.5
  • Champagne flute
  • Indicates thick medial and lateral cortices and a large posterior cortex
  • Femoral prosthesis suggested = press fit
  1. Type B
  • CC ratio 0.5-0.75
  • Indicates bone loss at the medial and posterior cortices
  • Femoral prosthesis suggested = press fit or cemented
  1. Type C
  • CC ratio >0.75
  • Stovepipe
  • Indicates a stovepipe appearance due to complete loss of both the medial and the posterior cortex and a widened intramedullary diameter
  • Femoral prosthesis suggested = cemented
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3
Q

What is the most common indication for revision THA?

[Bone Joint J 2016;98-B(1 Suppl A):44–9]

A

Instability

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4
Q

What is the definition of early and late THA dislocators?

[Bone Joint J 2016;98-B(1 Suppl A):44–9][The Journal of Arthroplasty 33 (2018) 1316e1324]

A
  1. Early dislocator
  • Dislocation within 2 years of surgery
  • One study showed 59% of dislocations in first 3 months, 77% within first year
  1. Late dislocator
    * Dislocation beyond 2 years of surgery
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5
Q

How do the etiologies of THA instability differ in early vs. late dislocations?

[Intl. Orth. (SICOT) (2017) 41:661–668]

A
  1. Early
    * Most commonly due to malposition
  2. Late
  • Eccentric liner wear
  • Implant loosening (subsidence/migration or rotation of the cup)
  • Abductor muscle damage
  • Greater trochanter disruption (due to osteolysis)
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6
Q

What are the types of THA instability described by Wera and Paprosky (Rush University Group)?

[Bone Joint J 2016;98-B(1 Suppl A):44–9]

A
  1. Type I - acetabular component malposition
  2. Type II - femoral component malposition
  3. Type III - abductor deficiency
  4. Type IV - soft tissue/bony impingement
  5. Type V - eccentric polyethylene wear
  6. Type VI - unknown etiology
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7
Q

What are the patient risk factors for postoperative THA instability?

[The Journal of Arthroplasty 33 (2018) 1316e1324]

A
  1. Age
    * Bimodal distribution of greatest risk <50 and ≥70
  2. Obesity
  3. Central, spinal and neuromuscular disorders
    * Eg. CP, polio, spinal injury, dementia
  4. Spinopelvic pathology
  • Poor spinopelvic mobility
  • Lumbosacral fusion
  • Ankylosing spondylitis
    5. THA for osteonecrosis
  • Tend to have reduced neck shaft angle and increased femoral version

***NOTE: sex is not a risk factor

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8
Q

What are THA dislocation risk factors?

[JAAOS 2004;12:314-321]

A
  1. Patient factors:
  • Female (2x more common than men)
  • Neuromuscular and cognitive disorders
    • CP, muscular dystrophy, parkinsons, psychosis, dementia, alcoholism
  • THA for management of fracture
  • History of surgery on the same hip (for any indication)
  • Patient non-compliance with activity restrictions
  1. Surgical factors:
  • Surgeon inexperience increases risk
  • Surgical approach
    • Posterior approach (increases risk of posterior dislocation)
  • Soft-tissue tension
    • Capsule repair reduces risk of dislocation
    • Restoration of abductor tension reduces risk of dislocation
      • Restore femoral offset (distance from the hip head centre to the tip of the GT or a line down the centre of the femoral canal)
      • Restore femoral neck length (distance from centre of the femoral head to the base of the femoral neck – top of the LT is the usual reference)
    • GT non-union or abductor avulsion increases risk of dislocation
  • Component positioning
    • Cup malposition
      • Normal position:
        • Inclination (40+/-10o)
        • Anteversion (20+/-5o)
        • AKA Lewinnek’s safe zone [Intl. Orth. (SICOT) (2017) 41:661–668]
        • ***NOTE: this safe zone has recently been questioned and it may be more important to match to patient anatomy
      • Retroversion = risk of posterior dislocation
      • Excessive anteversion = risk of anterior dislocation
      • Vertical cup = risk of posterior-superior dislocation
      • Horizontal cup = risk of inferior dislocation
    • Femoral stem malposition
      • Normal position = anteversion (10-15o)
      • Retroversion = risk of posterior dislocation
      • Excessive anteversion = risk of anterior dislocation
      • ***Note: anteversion is additive between the cup and stem
        • Excessive anteversion of one component may be acceptable but the additive effect if both are excessively anteverted = increased risk of dislocation
  • Impingement
    • Impingement of the femoral neck on a nonarticular surface can lever out of socket resulting in dislocation
      • Bone = osteophyte
      • Implant = neck and cup (‘intraprosthetic’)
      • Soft tissue = scar
        • In severe DDH it can occur between the GT and the ischium [Intl. Orth. (SICOT) (2017) 41:661–668]
    • Impingement can be reduced by:
      • Increasing head to neck ratio (head diameter/neck diameter)
        • Increase femoral head size (also increases ‘jump distance’)
        • Avoid skirts (plus size heads)
      • Clearing acetabular osteophytes, extruded cement, HO
      • Increasing femoral offset
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9
Q

What is the workup for THA instability?

[The Journal of Arthroplasty 33 (2018) 1325e1327]

A
  1. History
  • Mechanism of instability
    • Traumatic vs. positional
    • Hip in flexed position = posterior dislocation (eg. getting up from chair)
    • Hip in extended and ER position = anterior dislocation (eg. standing and turning)
  • Antecedent pain
    • Suggestive of infection, aseptic loosening, adverse local tissue reaction
  • Early vs. late dislocation
    2. OR notes
  • Surgical approach
  • Components used
    • Acetabulum, liner, femoral components
  • Complications
  1. Examination
  • Leg position
    • Flexed, adducted, IR = posterior dislocation
    • Extended, ER = anterior dislocation
  • Abductor strength
  • Trendelenburg sign/gait
  • LLD
  • Apprehension sign – indicates position at which hip becomes unstable
  1. Labs
    * CBC, ESR, CRP
  2. Radiographs
  • AP
    • Cup inclination
    • Eccentric poly wear
    • Head-neck ratio
    • Femoral offset
    • Centre of rotation
    • Height and integrity of GT
    • Impingement signs
      • 1.Osteophytes, neck and liner, GT
  • Cross-table lateral
    • Cup anteversion
      • Angle formed by the face of the acetabular component compared to a line perpendicular to the horizontal
        6. CT scan
  • Gold standard for assessment of acetabular and femoral component position
  • Acetabular component = axial CT scan
    • Angle formed by the face of the acetabular component relative to the perpendicular from a line drawn across both ischial spines
  • Femoral component = axial CT scan
    • Angle formed by the line parallel to femoral component through its widest metaphyseal portion relative to the ipsilateral femoral posterior condyle reference line at the distal femur
      1. MRI
  • MARS – metal artifact reduction sequence
  • Indicated in the setting of adverse local tissue reaction due to metal hypersensitivity to assess abductor integrity
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10
Q

What is the treatment of early THA instability?

A

Closed reduction

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11
Q

What is the treatment of late THA instability?

[Intl. Orth. (SICOT) (2017) 41:661–668] [Bone Joint J 2016;98-B(1 Suppl A):44–9]

A
  1. Type I – acetabular component malposition
  • Revision of acetabular component
  • Note – do not use elevated/lip liners in isolation to treat Type I as it increases risk of impingement, breakage and wear
  1. Type II – femoral component malposition
    * Revision of femoral component
  2. Type III – abductor deficiency
  • Constrained liner
  • Abductor repair and advancement
  1. Type IV – impingement
  • Excise offending osteophyte, soft tissue, HO, cement
  • Increase head-neck ratio
    • Increase femoral head size or consider dual mobility
  • Increase femoral offset
    • Lateralized liner, heads with longer necks (avoid skirts), extended offset stems
  1. Type V – eccentric poly wear
    * Modular head and liner exchange (increase femoral head size if possible)
  2. Type VI – unknown etiology
    * Constrained liner

***NOTE: in all cases consider increasing head size or dual mobility component

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12
Q

What are the disadvantages of constrained liners?

[Intl. Orth. (SICOT) (2017) 41:661–668]

A
  1. Acetabular and femoral component loosening
  2. Decreased ROM
  3. Increased poly wear
  4. Dissociation of the head from the liner (requires revision surgery)
  5. Liner breakage
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13
Q

What are the indications for constrained devices in THA?

[JAAOS 2018;26:479-488]

A
  1. Recurrent instability (three or more dislocations)
  2. Previous failed attempts at surgical stabilization
  3. Lack of identifiable causes of instability that could be corrected
  4. Central nervous system disorders
  5. Previous failure of a constrained device
  6. Prophylaxis in revision procedures in patients with inadequate posterior soft tissues and/or abductors
  7. Alcohol abuse
  8. Multidirectional instability intraoperatively
  9. Substantial abductor musculature deficiency
  10. Presence of an internal fixation device
  11. Extensive femoral or acetabular bone loss
  12. Inability to repair the greater trochanter
  13. Revision after arthrodesis or resection arthroplasty
  14. Revision after periprosthetic fractures
  15. Cognitive impairment preventing adherence to hip precautions
  16. Prophylaxis in the revision of metal-on-metal hip arthroplasty in patients with substantial soft-tissue defects after débridement of tissue granulomas or necrotic tissues
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14
Q

When considering constrained devices for THA what are the options?

[JAAOS 2018;26:479-488]

A
  1. Constrained liner
  2. Constrained tripolar (dual-mobility)
  3. Nonconstrained tripolar (dual-mobility)
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15
Q

What are the complications associated with dual mobility components?

A
  1. Increased poly volumetric wear
  2. Osteolysis
  3. Intraprosthetic dislocation
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16
Q

What is the intraoperative evaluation of combined anteversion in THA?

A
  1. With the leg positioned neutrally or with slight flexion of the hip; the leg is then internally rotated until the femoral head is symmetrically seated in the acetabular component. The degree of internal rotation represents the combined anteversion
  2. The safe zone for combined anteversion is 25-50° (goal of 35)
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17
Q

What imaging is required when managing a THA periprosthetic fracture?

[JAAOS 2009;17:677-688]

A
  1. AP pelvis
  2. AP and cross-table lateral of involved hip
  3. Full length femur views
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18
Q

What is the Vancouver classification of periprosthetic femur fractures?

[JAAOS 2009;17:677-688] [JAAOS 2014;22:482-490]

A

Classification is based on fracture location (A, B, C), stem stability, bone stock

  • Type A (trochanter region)
    • Vancouver AG – fracture of the GT
      • Stable when minimally displaced (held by digastric tendons of vastus lateralis and glut med.)
      • Usually related to wear-osteolysis of the GT
    • Vancouver AL – fracture of the LT
  • Type B (diaphysis including and just distal to the tip)
    • Vancouver B1 – stable implant
    • Vancouver B2 – loose implant
    • Vancouver B3 – loose implant + inadequate bone stock
  • Type C (diaphysis well distal to the tip of the implant)
    • Vancouver C – well distal to the implant + implant is stable
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19
Q

How do you assess for implant stability in setting of periprosthetic fracture?

[JAAOS 2009;17:677-688] [JAAOS 2014;22:482-490]

A

Pre-op:

  • Clinical features that may suggest a loose femoral stem prior to the fracture:
    • Startup pain (initiation of ambulation on rising from chair)
    • Groin or thigh pain
    • Pain with non-WB range of motion
    • Progressive limb shortening
    • Symptoms or signs of infection
  • Radiographic features:
    • Comparison to previous xrays
    • Subsidence
    • Radiolucency (cement-bone or cement-implant interface)
    • Cement mantle fracture
      • ***Note: cement mantle fracture alone is not indicative of a loose implant
    • Bone pedestal

Intra-op:

  • If distal stem is exposed attempt generating longitudinal shear (grasp femur with pointed reduction forceps and stem with kocher)
  • If distal stem is not exposed then arthrotomy and hip dislocation to assess stability
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20
Q

What is the management of Vancouver B1 periprosthetic fractures?

[JAAOS 2009;17:677-688]

A

ORIF

  • Locking plate
  • Fixation around the stem requires screws anterior/posterior to the stem or cables
  • Plate length – generally from vastus ridge (fixation in GT) to 2 cortical diameters distal to the tip of the stem or fracture site (3-5 bicortical screws distal to #)
  • Minimally invasive percutaneous plating preferred when possible
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21
Q

What is the management of Vancouver B2 periprosthetic fractures?

[JAAOS 2014;22:482-490]

A

Femoral component revision

  • Remove implant, cement and biomembrane
  • Long-stemmed, diaphyseal fitting stem
    • Monoblock, extensively porous-coated, non-cemented stem (>4-6cm of diaphyseal fixation)
    • Modular, tapered stems (<4-6cm of diaphyseal fixation)
  • Reconstruction of the femoral shaft
    • If little comminution do prior to insertion of the stem
    • If comminution exists insert the stem then reduce the fragments around the stem
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22
Q

What is the management of Vancouver B3 periprosthetic fractures?

[JAAOS 2014;22:482-490]

A

Femoral component revision

  • Tumor prosthesis
  • Modular tapered stem (requires <4-6cm of interference fit)
    • Splines maintain rotational stability
  • Cortical strut allograft
  • Allograft-prosthesis composite
  • Impact bone grafting
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23
Q

What are the indications for femoral revision in THA?

[J Am Acad Orthop Surg 2013;21: 601-612]

A
  1. Aseptic loosening
  2. Infection
  3. Osteolysis
  4. Periprosthetic fracture
  5. Component malposition
  6. Catastrophic implant failure
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24
Q

What is the Paprosky classification for femoral bone loss?

[J Am Acad Orthop Surg 2013;21: 601-612]

A
  1. Type I - minimal proximal metaphyseal bone loss
  2. Type II - moderate to severe proximal metaphyseal bone loss
  3. Type IIIA - severe proximal metadiaphyseal bone loss with ≥4cm of isthmus/diaphysis intact
  4. Type IIIB - severe proximal metadiaphyseal bone loss with <4cm of isthmus/diaphysis intact
  5. Type IV - severe metadiaphyseal bone loss with no intact isthmus/diaphysis
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25
Q

What are the reconstruction options for each Paprosky type of femoral bone loss?

A
  1. Type I - uncemented proximal fitting stem
  2. Type II - extensively porous-coated diaphyseal fitting stem
  3. Type IIIA - extensively porous-coated diaphyseal fitting stem
  4. Type IIIB - modular tapered stem
  5. Type IV - impaction grafting plus cemented stem OR APC stem
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26
Q

In the setting of loose femoral components (in THA) what is the observed proximal femoral remodeling?

[JAAOS 2013;21: 601-612]

A

Varus and retroversion

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27
Q

What is the most common approach used for femoral stem revision in THA?

[JAAOS 2013;21: 601-612]

A

Posterolateral

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28
Q

What is the indication for an ETO when revising the femurin THA?

[JAAOS 2013;21: 601-612][Instr. Course Lec. 2004]

A
  1. Significant varus remodeling
  2. Well-fixed uncemented stem
  3. Long column of cement below the stem
  4. Abductor tension adjustment
  5. Exposure of complicated acetabular reconstructions
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29
Q

When is an ETO indicated prior to hip dislocation (in revision THA)?

A

When dislocation is difficult and risks iatrogenic fracture

  • HO, protrusion, ankylosis, stiffness
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30
Q

What is the surgical technique for an ETO?

A
  1. Posterolateral approach
    * Vastus lateralis reflected anteriorly after release from linea aspera
    * Osteotomy is made just lateral to linea aspera (1/3 diameter of the femoral shaft)
    • The length is minimum 12cm from tip of GT usually to the tip of the stem
    • The distal osteotomy should not be transverse rather tapered
    • The osteotomy is completed through the medial cortex
    • The abductors and vastus lateralis remain attached the fragment and can be mobilized anteriorly
  2. Direct lateral approach [CORR 2003; 417: 210]
    * As above except the anterolateral osteotomy is made first followed by the posterior osteotomy then the fragment is mobilized posterior
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31
Q

How is the ETO reapproximated and fixed?

A
  1. Distal Luque wire or cable to prevent propagation of osteotomy prior to implant insertion
  2. Multiple Luque wires or cables for final fixation
  3. Strut allograft if bone loss
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32
Q

What are the complications of trochanteric osteotomy (in revision THA)?

A
  • Nonunion
  • Migration
  • Iatrogenic fracture
  • Fracture of the osteotomy fragment
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33
Q

What instruments should be available to facilitate femoral stem removal in revision THA?

[JAAOS 2013;21: 601-612]

A
  1. Manufacturer-specific explant tools
  2. Flexible osteotomes
  3. Trephines
  4. High-speed burrs (eg, pencil tip, carbide tip, metal cutting wheel)
  5. Ultrasonic cement removal instruments
  6. Universal extraction tools that allow attachment to the stem or taper.
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34
Q

What are indications for acetabular revision in THA?

[J Am Acad Orthop Surg 2013;21]

A
  1. Aseptic loosening
  2. Hip instability
  3. Periprosthetic osteolysis
  4. Periprosthetic infection
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35
Q

What is the Paprosky Classification of acetabular bone loss in THA (based on location or migration of the hip centre of rotation, degree of teardrop destruction, amount of ischial osteolysis, integrity of Kohler line)?[J Am Acad Orthop Surg 2013;21] 128-139

A

Type I - minimal bone loss

Type IIA - superomedial bone loss (intact rim)

  • <3cm of superior hip migration

Type IIB - superolateral bone loss (superior rim not intact)

  • <3cm of superior hip migration

Type IIC - medial wall bone loss

  • Moderate teardrop osteolysis and disruption of Kohler’s line

Type IIIA - “up and out”

  • 30-60% superolateral rim loss (10-2 o’clock)
  • >3cm superolateral hip migration
  • Moderate teardrop and ischial osteolysis
  • Kohler’s line intact

Type IIIB - “up and in”

  • >60% acetabular bone loss (9-5 o’clock)
  • Superomedial hip migration >3cm
  • Severe ischial and teardrop osteolysis
  • Complete disruption of Kohler’s line
  • May have pelvic discontinuity

***NOTE:

  1. Kohler’s Line —integrity of medial wall and superior anterior column
  2. Acetabular Tear Drop — integrity of medial wall and inferior portion of anterior and posterior column
  3. Ischial Lysis —integrity of posterior wall and posterior column
  4. Vertical Migration —integrity of superior dome
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36
Q

What is the Gross Classification System of acetabular bone loss?

[J Bone Joint Surg Am. 2016;98:233-42]

A
  1. Type I - no substantial loss of bone stock
  2. Type II - contained loss of bone stock
  3. Type III - minor column defect; uncontained loss of bone stock involving <50% of acetabulum
  4. Type IV - major column defect; uncontained loss of bone stock involving >50% of acetabulum
  5. Type V - pelvic discontinuity with uncontained loss of bone stock
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37
Q

What is the AAOS Classification System of acetabular bone loss?

[J Bone Joint Surg Am. 2016;98:233-42]

A

Type I - Segmental

  • Loss of part of the acetabular rim or medial wall

Type II - Cavitary

  • Volumetric loss in the osseous substance of the acetabular cavity

Type III - combined deficiency

  • Combination of segmental and cavitary

Type IV - pelvic discontinuity

  • Complete separation between the superior and inferior aspects of the acetabulum

Type V - arthrodesis

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38
Q

What is the treatment of acetabular defects based on Paprosky classification?

[J Am Acad Orthop Surg 2013;21]

A

Type I-IIB

  • Noncemented, porous-coated hemispheric implant with the use of adjunctive screw fixation

Type IIC

  • As above PLUS bone grafting of the medial defect

Type IIIA

  • Noncemented, porous hemispheric implant, with supplemental porous metal augments or structural graft

Type IIIB

  • Noncemented acetabular device must be used in conjunction with structural allograft, a reconstruction cage, modular porous metal augments, or a combination of these options.
  • May be associated with pelvic discontinuity
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39
Q

What is the treatment of acetabular defects based on the Gross classification?

[J Bone Joint Surg Am. 2016;98:233-42]

A

Type I

  • Uncemented or cemented hemispherical acetabular component

Type II

  • Uncemented hemispherical acetabular component and morselized bone-grafting

Type III

  • Uncemented hemispherical acetabular component and minor column graft or metal augment

Type IV

  • Major column graft protected by a reconstruction cage or metal augment protected by a reconstruction cage

Type V

  • Cup-cage reconstruction with major column graft or metal augment

***NOTE – major column graft = allograft acetabular bone is used as a graft and shaped to fit the defect

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40
Q

What is the preferred approach for acetabular revision surgery?

[J Am Acad Orthop Surg 2013;21]

A

Posterolateral

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41
Q

What instrumentation is need for removal of a well fixed acetabular component?

[J Am Acad Orthop Surg 2013;21]

A

Explant device

  • Allows for safe, quick and bone conserving removal
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42
Q

What are the treatment options available when reconstructing the acetabulum in revision THA?

[J Am Acad Orthop Surg 2013;21]

A
  1. Uncemented hemispheric cup +/- screw augmentation +/- bone grafting contained defects
  2. Uncemented hemispheric cup + structural autograft or metal augment
  3. Structural allograft or metal augment protected by cage + cemented liner
  4. Cup-cage construct +/- metal augment or structural graft
  5. Oblong cup
  6. Custom triflange
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43
Q

What is the definition of an antiprotrusio cage, what is the indication for same?

[J Bone Joint Surg Am. 2016;98:233-42]

A
  1. Cage that extends from ilium to ischium
    * Note – more rigid than cage used in the cup cage construct
  2. Indication – significant bone loss where uncemented hemispherical cup can not achieve stability even with use of metal augments, protection of structural allograft or cage when addressing segmental defect >50% (Gross IV)
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44
Q

What are the advantages and disadvantages of a cage in revision THA?

[J Am Acad Orthop Surg 2013;21]

A

Advantages

  • Ability to cement a liner in any orientation independent of cage positio
  • Can combine antibiotics in cement

Disadvantage

  • Risk of cage fracture or loosening due to lack of biological ingrowth
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45
Q

What are the advantages and disadvantages of metal augments in acetabular reconstruction?

[J Bone Joint Surg Am. 2016;98:233-42]

A

Advantages

  • Improved bone ingrowth
  • No resorption
  • No disease transmission
  • Convenient (off-the-shelf)

Disadvantages

  • No bone stock restoration
  • Potential third body wear secondary to loose cage or cup
46
Q

What are the indications for cup-cage constructs?

[J Am Acad Orthop Surg 2013;21]

A
  1. Paprosky Type IIIA and IIIB
  2. Pelvic discontinuity
    * Cage protects the cup while biological ingrowth occurs in the cup
47
Q

What are the causes of femoral head AVN?

[JAAOS 2014;22:455-464]

A
  1. Ischemia due to vascular disruption
    * Femoral head fracture, hip dislocation, surgery
  2. Ischemia due to vascular compression or constriction
    * Corticosteroids and alcohol (increased intraosseous pressure due to fatty infiltration)
  3. Ischemia due to intravascular occlusion
  • Sickle cell
  • Thrombophilia
  • Embolization (fat, air)
    • Dysbaric disorders (decompression sickness, “the bends”/Caisson disease)
      1. Direct cellular toxicity
  • Irradiation, pharmacologic agents
    5. Altered mesenchymal cell differentiation
  • Due to corticosteroids, alcohol
    6. Others
  • Viruses (CMV, hepatitis, HIV, rubella, varicella)
  • Hematologic diseases (eg. Leukemia)
  • Marrow-replacing diseases (eg. Gauchers disease)
  • Idiopathic
  • Autoimmune diseases (eg. Lupus)
  • Transplant patient
  • HIV meds (protease inhibitors)
48
Q

What is the classification of femoral head AVN?

[JAAOS 2014;22:455-464]

A
  1. Ficat and Arlet
  • Stage 1 = normal
  • Stage 2A = sclerotic or cystic lesions (no crescent sign)
  • Stage 2B = sclerotic or cystic lesions with crescent sign (subchondral collapse without flattening of the femoral head)
  • Stage 3 = flattening of the femoral head
  • Stage 4 = osteoarthritis with decreased joint space and articular collapse
  1. Steinberg (University of Pennsylvania) classification (modification of Ficat by addition of MRI/bone scan)
  • Stage 0 = normal radiograph + normal MRI/bone scan
  • Stage 1 = normal radiograph + abnormal MRI/bone scan
  • Stage 2 = lucent and sclerotic changes
  • Stage 3 = subchondral collapse (crescent sign) of femoral head without flattening
  • Stage 4 = flattening of the femoral head
  • Stage 5 = joint narrowing and/or acetabular changes
  • Stage 6 = advanced degenerative changes
49
Q

What are the risk factors for progression and flattening of the femoral head in context of AVN?

[JAAOS 2014;22:455-464]

A
  1. Extent of the osteonecrotic lesion
    * Assessed by modified Kerboul method OR proportion of the cross-sectional area of the head
  2. Location of the lesion in the femoral head
  3. Presence of bone marrow edema in the proximal femur
50
Q

How can collapse of the femoral head be predicted based on MRI?

[JBJS 2006 Nov;88 Suppl 3:35-40.]

A

Modified Kerboul method

  • The arc of the femoral surface involved by necrosis on a midcoronal plus the midsagittal arc = combined angle
  • High risk = combined angle >240
  • Moderate risk = combined angle 190-240
  • Low risk = combined angle <190
51
Q

What are femoral head AVN treatment options?

[JAAOS 2014;22:455-464]

A
  1. Bisphosphonates
  2. Femoral head preserving options
  • Core decompression
  • Core decompression +/- nonvascularized graft, vascularized graft, stem cells, biologic adjuncts (eg. BMP), tantalum implant
  • Rotational osteotomies (transtrochanteric or intertrochanteric)
  1. THA
  2. Hip resurfacing – limited use due to concern regarding bone quality for fixation and metallic wear debri from metal-on-metal
52
Q

What are advantages of hip resurfacing?

[J Am Acad Orthop Surg 2006;14:454-463]

A
  1. Preserves bone on the femoral side
  2. Less stress shielding of the proximal femur compared to THA (resulting in better bone density)
  3. Lower dislocation rates
  4. Easier to revise the femoral component compared to THA
53
Q

What are disadvantages of hip resurfacing?

A
  1. Cannot correct for LLD
  2. Cannot correct femoral offset
  3. Lack modularity
54
Q

What are indications for hip resurfacing?

[J Am Acad Orthop Surg 2011;19:236-241]

A
  1. Arthritic hip conditions
  • Primary OA
  • Posttraumatic OA
  • Osteonecrosis of the femoral head
    • Without cysts >1cm in femoral neck
    • Crowe type I and II dysplasia with associated degeneration
  1. Good proximal femoral bone stock
  2. Patients with proximal femoral deformity making total hip arthroplasty difficult
  3. Patients with high risk of sepsis due to prior infection or immunosuppression
  4. Patients at risk of dislocation (neurological conditions, ETOH, etc.)
  5. Retained hardware that precludes stemmed femoral component (eg. IM nail)
55
Q

What is the ideal candidate for hip resurfacing?

[J Am Acad Orthop Surg 2011;19:236-241]

A
  1. Young (<65)
  2. Male
  3. Large stature
  4. End-stage articular degeneration
  5. Excellent bone quality
  6. Minimal deformity
56
Q

What are contraindications to hip resurfacing?

[J Am Acad Orthop Surg 2011;19:236-241] [J Am Acad Orthop Surg 2006;14:454-463]

A

Absolute contraindications

  • Severe bone loss of the femoral head
  • Large femoral neck cysts
  • Small or bone-deficient acetabulum
  • Active infection

Relative contraindications

  • Severe osteoporosis
  • Age >65
  • BMI >35
  • Coxa vara (increased risk of femoral neck fracture)
  • Leg length discrepancy > 2cm
  • Female (particularly of childbearing age due to metal ions)
  • Unfavourable proximal femoral bone shape (eg. diameter of the femoral head is not larger than the diameter of the neck (CAM deformity),
  • Deformity from SCFE
  • Center of rotation of the femoral head is significantly displaced from the axis of the femoral neck
    • Short-wide femoral neck as in LCP)
  • Sensitivity to meta
    • Renal insufficiency (due to impaired metal ion elimination)
57
Q

What are complications following hip resurfacing?

A
  1. Femoral neck fracture
  2. Aseptic loosening
  3. Metal ion reactions (adverse local soft-tissue reactions, delayed hypersensitivity reactions, pseudotumor)
  4. HO
58
Q

What are the factors that increase the risk for femoral neck fracture in hip resurfacing?

A
  1. Patient factors
    * Obesity, osteoporosis, inflammatory arthritis, femoral neck cysts
  2. Surgical factors
    * Femoral neck notching, implanting in varus, improper prosthesis seating
59
Q

What are the radiographic features of acetabular dysplasia in the adult?

[The Journal of Arthroplasty 30 (2015) 1105–1108]

A
  1. AP pelvis
  • Lateral center edge angle (LCEA) <20
  • Acetabular index >10
  1. False profile view (patient is 65 degrees oblique to xray beam)
    * Anterior center edge angle (ACEA) <18
60
Q

What is the Crowe classification for hip dysplasia?

[J Am Acad Orthop Surg 2002;10:334-344]

A
  • Four categories based on the extent of proximal migration of the femoral head
  • Calculated on an AP pelvis xray by measuring the vertical distance between the inter-teardrop line and the junction between the femoral head and medial edge of the neck.
  • The amount of subluxation is the ratio between this distance and the vertical diameter of the undeformed femoral head (gives the %)
  • If both femoral heads are deformed the reference vertical height is the pelvic vertical height (highest point on the iliac crest to the inferior margin of the ischial tuberosity)

Type 1 – <50% proximal migration of the femoral head

  • <10% of the vertical height of the pelvis

Type 2 – 50-75% proximal migration of the femoral head

  • 10-15% of the vertical height of the pelvis

Type 3 – 75-100% proximal migration of the femoral head

  • 15-20% of the vertical height of the pelvis

Type 4 - >100% proximal migration of the femoral head

  • >20% of the vertical height of the pelvis
61
Q

What is the Hartofilakidis classification?

[Orthop Clin N Am 43 (2012) 369–375]

A
  • Describes acetabular abnormality rather than degree of subluxation
  • Three categories:
    1. Dysplastic hip
    • The femoral head is contained within the original acetabulum despite the degree of subluxation
    • Acetabular deficiencies
    • Segmental deficiency of the superior wall
    • Secondary shallowness due to fossa covering osteophyte
  1. Low dislocation
  • The femoral head articulates with a false acetabulum that partially covers the true acetabulum to a varying degree
  • Acetabular deficiencies
  • Complete absence of the superior wall
  • Anterior and posterior segmental deficiency
  • Narrow opening and inadequate depth of the true acetabulum
  1. High dislocation
  • The femoral head is completely out of the true acetabulum and migrated superiorly and posteriorly to a varying degree
  • Acetabular deficiencies
  • Segmental deficiency of the entire with narrow opening
  • Inadequate depth
  • Excessive anteversion
  • Abnormal distribution of bone stock, mainly located superoposteriorly
62
Q

Described Acetabular Reconstruction in DDH

[J Am Acad Orthop Surg 2002;10:334-344]

A

Features of the acetabulum in DDH:

  • Shallow, deficient anteriorly, laterally and superiorly, anteverted
  • Goal when feasible is to place the acetabular component in the true acetabulum to restore the hip center

Crowe Type 1

  • Standard acetabular component in the true acetabulum, medialize to inner table if needed to obtain coverage
  • The acetabular component is usually small (38-52mm) with size usually being limited by the anterior and posterior dimensions of the native acetabular walls and distance between anterior and posterior columns

Crowe Type 2/3

  • Options
    • “Augmentation with bone graft”
      • Place acetabular component in the true acetabulum with augmentation of the superolateral defect (autograft femoral head)
        • Modular porous metal augments are also acceptable
    • “High hip centre”
      • Place the acetabular component superior to the true acetabulum in the ‘high hip centre’
    • “Medialization of the cup’
      • Place the acetabular component in a medialized position with intentional overreaming or even fracture of the medial wall

Crowe 4

  • Extra-small acetabular component in the true acetabulum without bone grafting
63
Q

What are the advantages and disadvantages of a high hip center reconstruction?

A

Advantages

  • Technically easier, rarely need bone graft

Disadvantages

  • Persistent limp
  • High dislocation rate
  • High rate of loosening
64
Q

Ideally, how much bone coverage should the acetabular component have?

A

75-80%

  • Minimum coverage for stable cup is 50-60%
65
Q

Femoral Reconstruction in DDH

[J Am Acad Orthop Surg 2002;10:334-344]

A

Features of the femur in DDH

  • Excessive anteversion
  • Coxa valga
  • Small medullary canal
  • Posteriorly located GT

Crowe 1/2

  • Reconstruction with either uncemented or cemented (avoid excessive anteversion)
  • Nonmodular, proximally porous-coated, metaphyseal-filling implants can be used when anatomic abnormalities are mild
  • Extensively porous coated diaphyseal fitting implants bypass the proximal deformities and allow for adjustments in version (cannot be used when canal is very small)
  • Modular implants allow use of proximally porous coated stem and adjust for proximal deformity
  • Cemented implants allow adjustments in version

Crowe 3/4

  • Femoral shortening is usually required
  • Options:
    • Combination of greater trochanteric osteotomy, sequential proximal femoral resection, and insertion of a cemented stem (technically easier)
    • Subtrochanteric shortening osteotomy and insertion of a uncemented stem
66
Q

What is the maximum that you can lengthen the femur?

A

10% (~4cm on average)

67
Q

What are the sequential steps to managing a Crowe IV hip?

A
  1. Posterolateral approach
  2. ‘Dislocate’ the hip and perform femoral neck osteotomy
  3. Prepare the femur
    * Ream and broach – if planning shortening osteotomy prepare canal further distally
  4. Perform subtrochanteric osteotomy
    * Allows visualization of the native acetabulum when rotated out of the way
  5. Identify cotyloid fossa of native acetabulum
  • Ligamentum teres can be a guide
  • Low threshold for intraoperative xray
  1. Prepare the acetabulum
  • Begin reaming with a very small reamer (confirm appropriate location with xray)
  • Sequential reaming and trial
  1. Shorten femur based on preoperative planning or overlap after trial reduction
  2. Trial reduction of femoral and acetabular implants
  3. Implant final femoral stem and acetabulum
    * Femoral stem options include Wagner type stem (fluted and tapered for rotational control) or standard diaphyseal fitting stem
  4. If indicated place clam shell bone graft with cerclage for rotational stability and aid in union
68
Q

What are the indications for a periacetabular osteotomy (Ganz/Bernese)?

[The Journal of Arthroplasty 30 (2015) 1105–1108]

A
  1. Physiologically young and healthy
    * Generally age <40
  2. Skeletally mature (closed physis)
  3. Active patient
  4. Symptomatic acetabular dysplasia
  5. Adequate hip ROM
    * Flexion >95, abduction >30
69
Q

What are the contraindications for a periacetabular osteotomy?

[The Journal of Arthroplasty 30 (2015) 1105–1108]

A
  1. Advanced OA (Tonnis grade ≥2)
  2. Physiologically older age
  3. Low pre-op functional scores
  4. Reduced hip ROM
  5. Obesity
70
Q

What are the features of the periacetabular osteotomy?

[JAAOS 2011;19:275-286]

A
  1. Approach – abductor-sparing modification of the Smith-Petersen anterior iliofemoral approach
  2. 4 osteotomies
  • Anterior ischium below the acetabulum; superior pubic ramus; supra-acetabular ilium; and posterior column, joining cut number one
  • ***Note – posterior column is left intact
  1. Acetabular repositioning
    * The acetabular fragment is tilted laterally, rotated inward, medialized, and extended (anteriorly tilted)
  2. Acetabular fixation
    * Achieved with three or four 4.5mm cortical screws
  3. Arthrotomy performed
  • Labral debridement or repair
  • Osteochondroplasty at head neck junction allowing for increased hip flexion, internal rotation, and abduction
  1. Occasionally, in the presence of severe coxa valga, concomitant varus producing intertrochanteric femoral osteotomy is performed to optimize coverage
71
Q

What is the definition of acetabular protrusio?

[The Adult Hip, 2nd ed. 2007]

A
  1. Femoral head migration medial to the ilioischial line (Kohler’s line)
  2. Centre-edge angle of Wiberg > 40°(normal = 36°)
72
Q

What is the definition of coxa profunda?

A

Deep hip socket where the medial wall of the acetabulum is medial to the ilioischial line (but the femoral head is not)

73
Q

Describe acetabular reconstruction in primary THA in setting of acetabular protrusio

[The Adult Hip, 2nd ed. 2007]

A
  1. Consider femoral neck cut insitu
    * Femoral head can be removed piecemeal or reamed out
  2. Medial defect autologous bone grafting from the femoral head with a uncemented porous coated cup relying on rim fit to restore the hip centre
74
Q

What are causes of secondary protrusio acetabuli?

[J Am Acad Orthop Surg 2001;9:79-88]

A
  1. Inflammatory – RA, AS, psoriatic arthritis, JRA
  2. Metabolic – Paget’s, OI, osteomalacia, hyperparathyroidism
  3. Trauma – acetabular fracture
  4. Genetic – Ehler-Danlos, Marfans, Sickle cell
  5. Neoplastic – hemangioma, mets, neurofibromatosis, radiation-induced osteonecrosis
  6. Infectious – TB, strep, staph, gonococcus
75
Q

Based on registry data, what are the most common reasons for THA revision?

[JAAOS 2017;25:288-296]

A
  1. Instability (22%)
  2. Loosening (20%)
  3. Infection (15%)
  4. Implant failure (10%)
  5. Other mechanical problems (8%)
  6. Osteolysis (7%)
  7. Periprosthetic fracture (6%)
  8. Bearing surface wear (6%)
  9. Other mechanical complications (5%)
76
Q

What are the indications for isolated head and liner exchange?

[JAAOS 2017;25:288-296]

A
  1. Eccentric polyethylene wear
  2. Femoral and/or acetabular osteolysis
  3. Acute postoperative/hematogenous prosthetic infection
  4. Hip instability
  5. Squeaking
  6. Liner/head dissociation
  7. Liner fracture
77
Q

How do you assess for (THA) poly wear radiographically?

[JAAOS 2017;25:288-296]

A

Compare distance from superior rim of the acetabular component to superior aspect of femoral head with the distance from the inferior aspect of the femoral head to the inferior rim of the acetabular component (Compare A to B in image).

78
Q

How do you assess for osteolysis on the acetabular and femoral sides based on radiographs?

[JAAOS 2017;25:288-296]

A
  1. Acetabular osteolysis – assess the 3 Charnley zones
  2. Femoral osteolysis – assess the 14 Gruen zones

***Use multiple plain radiograph views and serial xrays to assess progression

79
Q

What is the definition of a well fixed acetabular component based on radiographs?

[JAAOS 2017;25:288-296]

A

No radiolucent lines measuring >1mm in any two zones on an AP radiograph

80
Q

What equipment and preparation is needed for an isolated liner and head exchange?

[JAAOS 2017;25:288-296]

A
  1. Previous surgical notes and implant stickers
  2. Manufacturer’s liner removal and insertion tools
  3. Modular heads of various sizes and neck lengths
  4. Liner options (eg. offset, constrained)
  5. Bone allograft (frozen femoral head allograft)
  6. Femoral and acetabular components in event revision is necessary
81
Q

After trial reduction how is hip stability assessed intraop?

[JAAOS 2017;25:288-296]

A

Hip stability can be characterized as the ability to achieve:

  • Flexion >90° with the hip in neutral abduction and rotation
  • >45° of internal rotation with the hip in 90° of flexion
  • >15° of external rotation with the hip in full extension
82
Q

What are the technical aspects of cementing a liner into a well fixed acetabular component?

[JAAOS 2017;25:288-296]

A
  1. Prepare the acetabular component by using a high speed burr to score radial and circumferential grooves (~2mm in width and depth)
  2. If using a liner not designed for cementing it should be prepared with similar grooves on the backside
    * Ensure the poly is of adequate thickness to allow for the grooves
  3. The cement mantel should be ~2mm thick
83
Q

How can osteolytic defects be addressed on the acetabular side?

[JAAOS 2017;25:288-296]

A

Bone graft can be passed through the central hole and drill holes or through holes burred in the acetabular component

84
Q

What is the definition of pelvic discontinuity?

[JAAOS 2017;25:330-338]

A

Separation of the ilium superiorly from the ischiopubic segment inferiorly

85
Q

What is the etiology of pelvic discontinuity?

[JAAOS 2017;25:330-338]

A
  1. Most commonly – represent chronic nonunited stress fracture through severely deficient acetabular bone
  2. Others
  • Trauma
  • Infection
  • Extensive acetabular reaming
  • Impaction of press-fit acetabular components
86
Q

What are the reported risk factors for pelvic discontinuity?

[JAAOS 2017;25:330-338]

A
  • Female
  • RA
  • Irradiation
87
Q

What are the radiographic findings associated with pelvic discontinuity?

[JAAOS 2017;25:330-338]

A
  1. AP pelvis
  • Visible fracture line
  • Obturator ring asymmetry
  • Medial migration of the inferior hemipelvis with disruption of Kohlers line
  1. Cross-table lateral
    * Visible fracture line through posterior column
  2. Judet views
    * Fractures through both the anterior and posterior columns
88
Q

What are the goals of reconstruction in the setting of pelvic discontinuity?

[JAAOS 2017;25:330-338]

A
  1. Obtaining rigid and durable fixation of the acetabular component to the pelvis (preferably noncemented)
  2. Create a unitized pelvis either by healing across the discontinuity (direct bone to bone) or by healing of the pelvis to the superior and inferior aspects of the acetabular construct (bone-construct-bone)
89
Q

What is the preferred approach for reconstruction?

[JAAOS 2017;25:330-338]

A

Posterolateral

  • Excellent acetabular exposure including the posterior column and ilium
90
Q

What are the surgical options available to address pelvic discontinuity?

[JAAOS 2017;25:330-338]

A
  1. Posterior column compression plating and hemispheric acetabular component
  • Should augment with 3-4 screws (ideally into ischium and superior ramus)
  • Indications:
    • Acute pelvic discontinuity
    • Intraoperative discontinuity
    • Chronic discontinuity and good bone stock
  1. Cup-cage construct
  • Cup = Highly porous metal jumbo acetabular component (≥62mm in women and ≥66mm in men) +/- highly porous metal augments
  • Cage = placed over the cup and spanning from ilium to ischium
  • Cup and cage are unitized by a screw that passes through cage, cup and into host bone
  • Polyethylene liner is cemented into the cup cage construct
  • Indications – compromised bone quality or quantity (including irradiated bone)
  1. Distraction method
  • Stability is achieved by distraction of the discontinuity and resulting elastic recoil of the pelvis
    • Further stability is achieved with screws into the superior and inferior hemipelvis
    • Healing occurs to the cup rather than across the fracture
  • Technique involves sequential reaming until the anterosuperior and posteroinferior margins of the acetabulum are engaged
    • A jumbo cup 6-8mm larger than the last reamer is used to obtain the distraction
      • It is fixed in place by press fit supplemented by screws into the ilium and ischium
  • Indications – stiff discontinuity where modest distraction leads to elastic recoil
    4. Custom triflange components
  • Custom designed porous and/or hydroxyapatite coated, titanium acetabular components with iliac, ischial, and pubic flanges
  • Rigid fixation promotes healing of the discontinuity
  • CT scan required for customization
91
Q

What is the cause of corrosion at the head neck junction?

[JAAOS 2016;24:349-356]

A

Mechanically-assisted crevice corrosion (MACC)

  • This process results in the mechanical degradation of the passivation layer secondary to micromotion at modular junctions, leading to electrochemical corrosion and ion release [J Bone Joint Surg Am. 2017;99:1489-501]
  • The presence of corrosion and corrosion byproducts incites a lymphocytic T-cell-mediated tissue response resulting in tissue necrosis
92
Q

What is the clinical presentation of corrosion at the head neck junction?

[JAAOS 2016;24:349-356]

A
  1. Adverse local tissue reaction (ALTR)
    * Pain, palpable mass (pseudocyst), limp (abductor muscle damage), late instability
  2. Gross failure of the trunnion
93
Q

What imaging is most useful in the workup of trunnionosis?

[JAAOS 2016;24:349-356]

A

MARS (metal artifact reduction sequence MRI)

  • Demonstrates fluid collections, pseudocysts and masses, abductor and soft tissue destruction
94
Q
A
95
Q

What is expected finding for metal ions in trunnionosis?

[J Bone Joint Surg Am. 2017;99:1489-501]

A

Co:Cr ratio of 5:1

96
Q

What is the management of corrosion of the head neck junction?

[JAAOS 2016;24:349-356]

A
  1. Intraoperative frozen sections and culture
  2. Inspect head and neck junction for corrosion
  3. Assess modular head stability
  4. Disengage head from trunnion
  5. Well-fixed femoral component = use a ceramic head with a titanium alloy adaptor sleeve placed onto a cleaned trunnion
    * Consider liner exchange [J Bone Joint Surg Am. 2017;99:1489-501]
97
Q

What are two theoretical advantages of metal on metal THA?

[JAAOS 2015;23724-731]

A
  1. Less volumetric wear (less wear induced osteolysis)
  2. Larger head sizes (greater stability and ROM)
98
Q

What is the spectrum of findings resulting from the release of metal particles and metal ions into the periprosthetic space?

[JAAOS 2015;23724-731]

A

ARMD – adverse reaction to metal debris

  • Necrosis
  • Osteolysis
  • Large sterile hip effusion
  • Pseudotumors (solid and cystic masses)
99
Q

What is the characteristic histological findings of a MOM reaction?

[JAAOS 2015;23724-731]

A

ALVAL

  • Aseptic lymphocyte-dominant vasculitis-associated lesion
100
Q

What are risk factors for ARMD and pseudotumor formation?

[International Orthopaedics (SICOT) (2017) 41:885–892]

A
  1. Female
  2. Acetabular inclination >50
  3. Poor implant track record
  4. Dysplasia
101
Q

What is the workup of a patient with a MOM THA?

[JAAOS 2015;23724-731]

A
  1. History
  2. Physical
  3. Radiographs
    * Evaluate for loosening, osteolysis, larger femoral head sizes (higher rates of revision), cup abduction angle ≥50° (edge loading)
  4. Bloodwork
  • CBC
  • ESR/CRP
  • Serum metal ion quantification – cobalt and chromium levels
    • ≥7ppb for cobalt and chromium is recommended cutoff for obtaining MARS or US
  1. Possible hip aspiration
  • Higher number of cells and a larger percentage of monocytes are concerning
  • “dishwater” appearance is typical
  1. MARS
  • Metal artifact reduction sequence
  • Evaluate for pseudotumor, hip abductor integrity
  1. Possible ultrasound
    * Indicated if patient unable to undergoes MARS, detection of effusion and guided biopsy
102
Q

What is the differential diagnosis of a painful THA?

[JAAOS 2015;23724-731]

A
  1. Intrinsic Causes
  • Infection
  • Aseptic loosening
  • Instability
  • Periprosthetic fracture
  • Adverse reaction to metal debris
  • Trochanteric bursitis
  • Tendinitis (iliopsoas or rectus femoris)
  1. Extrinsic Causes
  • Spinal pathology (disk herniation, spondylolisthesis)
  • Peripheral vascular disease
  • Hernia (femoral, inguinal)
  • Malignancy/metastases
  • Metabolic bone disease
  • Peripheral nerve injury (sciatic, femoral, meralgia paresthetica)
  • Complex regional pain syndrome
  • Psychological disorder
103
Q

What is the algorithm for the evaluation and management of a patient with a MOM THA?

[JAAOS 2015;23724-731]

A
  1. Asymptomatic
  • Workup:
    • Obtain serial radiographs and check implant track record AND
    • Evaluate metal ions (if previously obtained or available)
  • Low-Risk Group
    • Criteria
      • Radiographs
        • Cup abduction <50
        • No osteolysis
        • No loosening
      • Good implant track record
      • Metal ion levels <7ppb
    • Plan = clinical followup annually
  • Moderate-Risk Group
    • Criteria
      • Radiographs
        • Cup abduction >50 OR
        • Osteolysis OR
        • Loosening
    • Obtain MARS MRI or US
      • No fluid/mass
        • Plan = clinical followup every 3-6 months
      • Presence of fluid/mass
        • Plan = consider revision THA if progression of imaging abnormality, new onset of symptoms or increasing metal ion levels
          2. Symptomatic
  • Workup:
    • Rule out other causes
    • Obtain MARS MRI or US
    • Obtain metal ion levels
  • Moderate-Risk group
    • Metal ions <7ppb and no fluid/mass
      • Plan = clinical followup every 3-6 months
  • Moderate to High-Risk group
    • Metal ions >7ppb and no fluid/mass OR
    • Metal ions <7ppb and presence of fluid/mass
      • Plan:
        • Consider revision THA if cup abduction >50 OR
        • Osteolysis or loosening OR
        • Poor implant track record
  • High-Risk group
    • Metal ions >7ppb and presence of fluid/mass
      • Plan = recommend revision THA
104
Q

What is the recommended THA revision for MOM complications?

[JAAOS 2015;23724-731]

A
  1. Send periprosthetic tissue for frozen section, standard culture and pathology to evaluate for ALVAL
  2. Excise pseudotumor and associated necrotic tissue and metal debris
  3. Revise to metal-on-poly or ceramic-on-poly
  4. Constrained liner or salvage procedures for abductor deficiency
105
Q

Following revision surgery of MoM THA, when can the metal ion levels be expected to return to normal?

[International Orthopaedics (SICOT) (2017) 41:885–892]

A

3 months

106
Q

What systems are affected with systemic metal ion toxicity?

[Clin Toxicol (Phila). 2014 Sep-Oct;52(8):837-47]

A
  1. Neurologic
  • Peripheral neuropathy
  • Sensorineural hearing loss
  • Cognitive decline
  • Visual impairment
  1. Cardiac
    * Cardiomyopathy
  2. Thyroid
    * Hypothyroidism
107
Q

What are the advantages of hemiarthroplasty and THA in hip fracture management?

[JAAOS 2018;26:717-726]

A
  1. Hemiarthroplasty
  • Shorter surgical time
  • Less blood loss
  • Less technical
  • More stable
  • Fewer postoperative complications
  1. THA
  • Better pain relief
  • Lower longterm reoperation rates
108
Q

What are the implant options for hemiarthroplasty?

[JAAOS 2018;26:717-726]

A
  1. Unipolar or bipolar
  2. Fixed or modular
  3. Cemented or noncemented
109
Q

What are the modes of failure of a hemiarthroplasty?

[JAAOS 2018;26:717-726]

A
  1. Pain
  • Intrinsic causes
    • Acetabular wear/erosion
    • Femoral aseptic loosening
  1. Infection
  2. LLD
  3. Instability
  4. Periprosthetic fracture
110
Q

What is the management of a CoC catastrophic component failure?

[J Arthroplasty. 2017 Jun;32(6):1959-1964]

A

Revision surgery

  • Synovectomy and irrigation
    • Extensive synovectomy and thorough irrigation of the articular space
      • Complete elimination of ceramic fragments is of paramount importance to increase the survivorship of the new articulation
  • Revise to ceramic on poly
    • A well-fixed acetabular component should be removed if either the locking mechanism is damaged or the component is malpositioned
    • If the femoral stem taper is damaged, the femoral stem should be removed
    • However, if minimal damage is present, the femoral stem may be retained and revised using a fourth generation ceramic head with a titanium sleeve
    • Metal bearings should be avoided and revision with ceramic bearings should be performed whenever possible.

2. JAAOS Summaries (2016-2019) (5 decks)

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