Updated: 9/11/2018

THA Dislocation

Topic
Review Topic
0
0
Questions
28
0
0
Evidence
25
0
0
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Introduction
  • Dislocation following THA is a common reason for revision
  • Epidemiology
    • incidence 1-3%
    • 70% occur within first month
    • 75-90% posterior
  • Mechanism
    • anterior
      • extension and external rotation of hip
    • posterior
      • flexion, internal rotation, adduction of hip
  • Risk factors
    • prior hip surgery (greatest risk factor)
    • female sex
    • >70-80 years of age
    • posterior surgical approach
      • repairing capsule and reconstructing external rotators brings dislocation rate close to anterior approach
    • malpositioning of components 
      • ideal positioning of acetabular component is 40 degrees of abduction and 15 degrees anteversion  
      • in general, excessive anteversion increases risk of anterior hip dislocation; excessive retroversion increases risk of posterior hip dislocation
    • spastic or neuromuscular disease (Parkinson's)
    • drug or alcohol abuse
    • decreased femoral offset (decreases tissue tension and stability)
    • decreased femoral head to neck ratio
Presentation
  • History
    • often reports activity that puts patient in a position that provokes dislocation (hip flexion, adduction, internal rotation)  
      • shoe tying 
      • sitting in low seat or toilet
Imaging
  • Radiographs
    • recommended views
      • AP
      • cross-table lateral
    • findings
      • increased acetabular inclination > 60°
      • increased acetabular anteversion > 20°
      • aceabular retroversion
      • look for eccentric position of femoral head as an indication of polyethylene wear and risk for impending dislocation
Treatment
  • Nonoperative
    • closed reduction and immobilization
      • indications
        • two-thirds of early dislocations can be treated with closed reduction and immobilization
      • technique
        • immobilize with hip spica cast, hip abduction brace, or knee immobilizer
  • Operative
    • polyethylene exchange
      • indications
        • stable well-aligned implants with extensive polyethylene wear thought to be sole reason for dislocation
    • revision THA 
      • indications
        • indicated if 2 or more dislocations with evidence of
          • implant malalignment
            • vertical acetabular component
            • acetabular retroversion
          • implant failure
          • polyethylene wear  
        • techniques
          • see below
    • conversion to hemiarthroplasty with larger femoral head
      • indications
        • for soft tissue deficiency or dysfunction
        • contraindicated if acetabular bone is compromised
        • older technique rarely used with development of dual mobility implants
    • resection arthroplasty
      • indications
        • when all options have been exhausted
        • significant bone loss and soft tissue deficiency
        • psychiatric patients who are dislocating for secondary gain
Technique
  • Revision THA
    • techniques to prevent future dislocation during THA include
      • realign components
        • indicated if malalignment explains dislocation
          • retroverted acetabulum
          • vertical acetabulum
          • short femoral neck 
          • lack of femoral neck offset
          • retroverted femoral component
      • head enlargement
        • optimize head-neck ratio
      • trochanteric osteotomy and advancement
        • places abductor complex under tension which increases hip compression force
      • conversion to a constrained acetabular component  
        • indications
          • recurrent instability with a well positioned acetabular component due to soft tissue deficiency or dysfunction   
      • conversion to dual mobility implant
      • conversion to tripolar construct
 
 

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Questions (28)
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(OBQ13.197) Figures A and B show pre- and post-operative radiographs of a sedentary 75-year-old female who underwent surgery on her left hip. Based on the radiographic findings, what was the most likely indication for revision surgery? Review Topic

QID: 4832
FIGURES:
1

Left acetabular fracture

1%

(20/3849)

2

Left acetabular cup osteolysis

11%

(420/3849)

3

Left femoral stem osteolysis

2%

(88/3849)

4

Left hip instability

85%

(3279/3849)

5

Left femoral stem valgus malalignment

1%

(26/3849)

L 2

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(OBQ11.26) A 73-year-old female undergoes a total hip arthroplasty (THA) using a cemented stem design shown in Figure A. She returns to clinic 3 years post-operatively with signifcant thigh pain. Current radiographs, shown in Figure B, demonstrate femoral subsidence. What affect does this have on the biomechanics of her THA? Review Topic

QID: 3449
FIGURES:
1

Excursion distance is decreased

4%

(140/3830)

2

Primary arc range is increased

2%

(72/3830)

3

Abductor complex tension is decreased

88%

(3363/3830)

4

Joint reactive forces are decreased

3%

(128/3830)

5

Femoral offset is increased

3%

(101/3830)

L 1

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(OBQ10.236) A 65-year-old male with chronic right hip pain undergoes the procedure seen in Figure A utilizing a posterior approach. Which of the following hip positions would put the patient at the greatest risk for dislocation? Review Topic

QID: 3335
FIGURES:
1

Abduction and external rotation

1%

(16/2554)

2

Flexion and external rotation

2%

(63/2554)

3

Flexion and internal rotation

95%

(2432/2554)

4

Extension and internal rotation

1%

(25/2554)

5

Extension and external rotation

1%

(14/2554)

L 1

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(OBQ10.15) All of the following are independent risk factors for dislocation after total hip arthroplasty EXCEPT? Review Topic

QID: 3103
1

Female gender

10%

(234/2293)

2

Osteonecrosis

32%

(725/2293)

3

Inflammatory arthritis

10%

(223/2293)

4

Post traumatic osteoarthritis

37%

(847/2293)

5

Age >70

11%

(254/2293)

L 5

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(OBQ10.98) A 68-year-old male 2 weeks status post left total hip arthroplasty experiences a painful clunk getting out of bed in the morning. He is unable to bear any weight on the left leg. A radiograph is provided in figure A. Following closed reduction under sedation, the hip continues to dislocate with flexion up to 90 degrees. Each of the following operative interventions will increase the stability of the hip EXCEPT: Review Topic

QID: 3192
FIGURES:
1

Revising the acetabular component to a more medialized position

81%

(2252/2784)

2

Advancing the trochanter distal on the femur

10%

(266/2784)

3

Converting to a femoral component with extended offset

3%

(85/2784)

4

Replacing the acetabular polyethylene with a constrained liner

4%

(121/2784)

5

Replacing the femoral head with a larger size

2%

(54/2784)

L 2

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(OBQ09.202) Which of the following situations is appropriate for revision of a total hip arthroplasty to a constrained acetabular liner? Review Topic

QID: 3015
1

Periprosthetic acetabular fracture with resulting pelvic discontinuity

1%

(18/1707)

2

Chronically infected total hip arthroplasty

0%

(6/1707)

3

Recurrent dislocations in a patient whose femoral component is positioned in 15° retroversion

4%

(62/1707)

4

Recurrent dislocations in a patient whose cup is positioned in 10° retroversion and 60° abduction

10%

(164/1707)

5

Recurrent dislocations in a patient whose cup is positioned in 20° anteversion and 40° abduction

85%

(1451/1707)

L 1

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(OBQ09.269) All of the following are acceptable indications for use of a constrained acetabular component EXCEPT: Review Topic

QID: 3082
1

Recurrent dislocations due to abductor insufficiency

4%

(68/1695)

2

Recurrent dislocations due to unsalvageable capsular attenuation

1%

(16/1695)

3

Recurrent dislocations due to severe polyethylene wear

84%

(1426/1695)

4

Recurrent late dislocations without component loosening or malposition

7%

(116/1695)

5

Recurrent dislocations due to cognitive or neuromuscular disease

4%

(67/1695)

L 2

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(OBQ09.126) A 60-year-old male had a total hip replacement 8 years ago. There is evidence of eccentric polyethylene wear and some retroacetbular osteolysis. You discuss treatment options of acetabular revision if the component is found to be loose intra-operatively versus isolated polyethylene exchange if the acetabular component is stable intra-operatively with the patient. What is the most common complication of isolated polyethylene exchange with bone grafting that should be disclosed? Review Topic

QID: 2939
1

Sciatic nerve injury

2%

(34/1567)

2

Intraoperative acetabular fracture

10%

(151/1567)

3

Postoperative hip instability

66%

(1031/1567)

4

Infection

11%

(167/1567)

5

Catastrophic implant failure

11%

(172/1567)

L 3

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(OBQ09.5) A 70-year-old man underwent total hip arthroplasty 4 months ago and has experienced 3 dislocations. Radiographs reveal no failure of the hardware and an acetabular component that has an abduction angle of 40 degrees and a version of 10 degrees retroverted. What is the most appropriate treatment for the recurrent dislocations? Review Topic

QID: 2818
1

hip abduction brace

1%

(26/2248)

2

revision of the acetabular liner to a constrained type

8%

(172/2248)

3

revision of the entire acetabular component

87%

(1951/2248)

4

revision of the femoral head to a larger size

3%

(59/2248)

5

revision to an extended offset prosthesis

1%

(23/2248)

L 1

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(OBQ08.260) What is the most common complication after revision of a total hip polyethylene liner in a patient with well-fixed femoral and acetabular shell components? Review Topic

QID: 646
1

dislocation

83%

(2281/2743)

2

failure of the femoral component

0%

(10/2743)

3

extensive osteolysis

5%

(144/2743)

4

failure of the fixation between the liner and the acetabular shell

9%

(258/2743)

5

fracture of the polyethylene

1%

(39/2743)

L 2

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(SAE07HK.48) Figure 27 shows the AP radiograph of a patient who has late instability. The problem most likely occurred as a result of Review Topic

QID: 6008
FIGURES:
1

greater trochanter detachment.

14%

(26/189)

2

femoral stem loosening.

6%

(12/189)

3

wear.

45%

(85/189)

4

osteolysis.

32%

(61/189)

5

infection.

2%

(3/189)

L 4

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(SAE07HK.90) A 68-year-old woman who underwent a right total hip arthroplasty 1 year ago has dislocated her hip five times since surgery. Radiographs show a retroverted acetabular component. What is the best treatment for this patient? Review Topic

QID: 6050
1

Use a constrained acetabular liner

2%

(3/137)

2

Revise the femoral component to provide greater femoral offset

1%

(1/137)

3

Revise the femoral head from a 28-mm head size to a 36-mm head size

2%

(3/137)

4

Revise the acetabular component to 15 degrees of anteversion and 45 degrees of abduction

95%

(130/137)

5

Perform a greater trochanteric osteotomy to improve soft-tissue tension

0%

(0/137)

L 1

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(SAE07HK.26) A 59-year-old woman who underwent a total hip arthroplasty 5 years ago now has recurrent dislocation following bariatric surgery and a weight loss of 200 lb. An attempt at converting to a larger head size and trochanteric advancement has failed. Her components are well aligned. What is the best course of action? Review Topic

QID: 5986
1

Resection arthroplasty

0%

(0/110)

2

Hip abduction brace

1%

(1/110)

3

Constrained acetabular liner

85%

(94/110)

4

Thermal ablation of the posterior capsule

1%

(1/110)

5

Conversion to a bipolar prosthesis

13%

(14/110)

L 1

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(SAE07HK.23) At the time of the revision surgery shown in Figure 14, the acetabular component was found to be stable. Polyethylene exchange with a standard ultra-high molecular weight polyethylene liner and grafting was performed. The patient is at significantly increased risk for Review Topic

QID: 5983
FIGURES:
1

loosening of the femoral component.

3%

(5/198)

2

loosening of the acetabular component.

19%

(37/198)

3

prosthetic hip dislocation.

39%

(78/198)

4

rapid wear of the polyethylene.

17%

(33/198)

5

continued expansion of the lytic defects.

23%

(45/198)

L 4

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(OBQ06.18) A 64-year-old healthy female patient underwent right total hip replacement (THR) through a posterior approach 6 months ago. She has now dislocated posteriorly 3 times, each followed by closed reduction under anesthesia in the operating room. A radiograph is provided in Figure A. Treatment should include: Review Topic

QID: 29
FIGURES:
1

Hip spica casting

0%

(2/2264)

2

Revision of the femoral component to a modular stem with retention of the acetabular component

1%

(22/2264)

3

Revision of the acetabular component

96%

(2171/2264)

4

Hip abduction bracing

1%

(20/2264)

5

Revision to a constrained liner with retention of the acetabular and femoral prostheses

2%

(39/2264)

L 1

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(OBQ04.64) A 62-year-old woman presents for her 1-year follow-up after a revision right total hip arthroplasty. She has no complaints of pain and has returned to all her activities of daily living. An AP radiograph is shown in Figure A. The black arrow in the radiograph indicates she is at higher risk for which of the following? Review Topic

QID: 1169
FIGURES:
1

Aseptic loosening

22%

(294/1314)

2

Aseptic lymphocytic vasculitis-associated lesions (ALVAL)

1%

(11/1314)

3

Dislocation

56%

(734/1314)

4

Third body wear

16%

(209/1314)

5

Catastrophic ceramic bearing failure

4%

(55/1314)

L 4

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