Updated: 7/7/2019

THA Stability Techniques

Topic
Review Topic
0
0
Questions
14
0
0
Evidence
19
0
0
https://upload.orthobullets.com/topic/5007/images/offset_900.jpg
https://upload.orthobullets.com/topic/5007/images/head-neck_ratio.jpg
https://upload.orthobullets.com/topic/5007/images/skirt.jpg
https://upload.orthobullets.com/topic/5007/images/jump..jpg
https://upload.orthobullets.com/topic/5007/images/liners.jpg
Introduction
  • Four important variables that help determine the stability of THA 
    • component design
    • component position
    • soft-tissue tensioning
    • soft tissue function
Component Design
  • Femoral component design
    • large femoral heads
      • decreased dislocation rates due to
        • head-neck ratio increased
          • definition
            • diameter of femoral head/diameter of femoral neck
          • importance
            • larger head-neck ratios allow greater arc range of motion prior to impingement   
        • skirts can be avoided
          • definition
            • skirts are attachments used to extend the length of the femoral neck
          • importance
            • skirts decrease the head-neck ratio
        • jump-distance is increased
          • definition
            • amount of translation prior to dislocation
          • importance
            • large femoral heads are seated deeper within the acetabulum, increasing jump-distance  
            • increase in jump-distance increases joint stability
        • a larger femoral head will not compensate for abductor deficiency or a vertically positioned cup
    • femoral offset
      • see "soft tissue tensioning" below
  • Acetabular component design
    • elevated rim liner
      • a posteriorly placed elevated rim liner may increase joint stability  
    • lateralized liner
      • increases soft-tissue tension by increasing offset  
      • has been shown to increase the risk of acetabular component loosening 
Component Position
  • Acetabular position 
    • recommendations   
      • anteversion  
        • 5° - 25°
      • abduction  
        • 30° - 50°
    • caveats
      • surgical approach may affect optimal position of implants
        • posterior approach should err towards more anteversion
        • anterior approach should err towards less anteversion
      •  Hypertrophy of the anterior inferior iliac spine may cause component impingement and instability  
    • complications
      • excessive retroversion  
        • posterior dislocation
      • excessive anteversion
        • anterior dislocation
      • excessive abduction (high theta angle, vertical cup) 
        • posterior superior dislocation  
        • eccentric polyethylene wear and late instability
      • excessive adduction (low theta angle, horizontal cup)
        • impingement in flexion
        • inferior dislocation
  • Femoral stem position
    • recommendations
      • 10°- 15° of anteversion
    • caveats
      • more difficult to adjust femoral component version in uncemented femoral components
  • Combined version
    • definition
      • femoral component anteversion plus acetabular component anteversion
    • recommendations
      • 37 degrees
Soft Tissue Tensioning
  • Restoration of offset
    • definition
      • perpendicular distance from femoral head center of rotation to the axis of the femur  
    • importance
      • increased offset leads to
        • increased soft-tissue tension
        • decreased impingement
        • decreased joint reaction force  
      • decreased offset may lead to 
        • instability
        • abductor weakness
        • gluteus medius lurch
      • increasing offset improves hip stability 
    • techniques to increase offset  
      • increasing length of femoral neck
      • decreasing neck-shaft angle
      • medializing the femoral neck while increasing femoral neck length
      • trochanteric advancement  
      • alteration of the acetabular liner (see "component design" above)
Soft Tissue Function
  • Three main factors controlling proper soft tissue function
    • central nervous system 
      • pathology that affects the central nervous system
        • stroke
        • cerebellar dysfunction 
        • dementia
        • MS
        • Parkinson's 
        • myelopathy
        • delirium
        • alcoholism
    • peripheral nervous system
      • pathology that affects the peripheral nervous system
        • spinal stenosis (gluteus medius is L5) 
        • peripheral neuropathy 
        • radiculopathy 
        • paralysis/paresis
    • local soft tissue integrity
      • trauma
      • myoligamentous disruption
      • deconditioning
      • aging process
      • poor health
      • irradiation
      • osteolysis 
      • collagen abnormalities
      • myopathy
      • malignancy
      • infection
 

Please rate topic.

Average 4.0 of 59 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (14)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

You have 100% on this question.
Just skip this one for now.

(OBQ13.259) An 83-year-old man, who had a total hip arthroplasty performed 13 years ago, is referred to your office for evaluation. He reports worsening groin pain over the past year, which has been increasing in frequency. Prior to this past year, he had no other complaints. His current radiograph is shown in Figure A. If he continues to ambulate with this implant, he is at greatest risk for which of the following? Review Topic

QID: 4894
FIGURES:
Type in at least one full word to see suggestions list
1

Infection

0%

(10/3606)

2

Acetabular component loosening

8%

(276/3606)

3

Femoral component loosening

3%

(105/3606)

4

Dislocation

87%

(3136/3606)

5

Periprosthetic fracture

1%

(49/3606)

L 2

Select Answer to see Preferred Response

SUBMIT RESPONSE 4

You have 100% on this question.
Just skip this one for now.

(OBQ10.75) A 67-year-old female underwent a total hip arthroplasty 6 months ago and has had recurrent prosthetic dislocations. Figure A is a representative drawing of the mechanism of her dislocation. During the time of surgery what is the most likely factor leading to the bone-on-bone impingement? Review Topic

QID: 3163
FIGURES:
Type in at least one full word to see suggestions list
1

Lateralizing the acetabular cup

1%

(20/1912)

2

Decreased femoral offset

82%

(1559/1912)

3

Increased femoral offset

5%

(101/1912)

4

Increased acetabular inclination (>55 degrees)

4%

(81/1912)

5

Small head-neck ratio (<2)

8%

(146/1912)

L 1

Select Answer to see Preferred Response

SUBMIT RESPONSE 2

You have 100% on this question.
Just skip this one for now.

(OBQ09.160) A 65-year-old female undergoes total hip arthroplasty. Instability of the prosthesis with straight hip flexion is identified during intra-operative range of motion testing. A fluoroscopic image is shown in figure A. Impingement is caused by the structure labeled with the asterisk. Which muscle originates upon this structure? Review Topic

QID: 2973
FIGURES:
Type in at least one full word to see suggestions list
1

Sartorius

3%

(80/2315)

2

Direct head of the rectus femoris

67%

(1553/2315)

3

Reflected head of the rectus femoris

25%

(583/2315)

4

Obturator externus

2%

(45/2315)

5

Obturator internus

2%

(35/2315)

L 3

Select Answer to see Preferred Response

SUBMIT RESPONSE 2
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

You have 100% on this question.
Just skip this one for now.

(OBQ07.213) In total hip arthroplasty, which of the following techniques will lead to improved stability by increasing the abductor tension? Review Topic

QID: 874
Type in at least one full word to see suggestions list
1

Use of a high offset femoral component

95%

(3204/3365)

2

Decreasing neck length

0%

(12/3365)

3

Use of a low offset femoral component

1%

(37/3365)

4

Increasing the head size

1%

(28/3365)

5

Medializing the acetabular component

2%

(76/3365)

L 1

Select Answer to see Preferred Response

SUBMIT RESPONSE 1

You have 100% on this question.
Just skip this one for now.

(OBQ07.117) Figure A depicts an individual seen from behind during a single-leg stance on the left lower extremity. Which of the following modifications during a left-sided total hip arthroplasty would exacerbate the abnormal findings present in Figure A? Review Topic

QID: 778
FIGURES:
Type in at least one full word to see suggestions list
1

Decreasing femoral offset

86%

(2279/2651)

2

Changing from a standard offset neck to an extended offset neck

7%

(198/2651)

3

Increasing femoral head size

0%

(9/2651)

4

Increasing femoral neck length

4%

(116/2651)

5

Moving acetabular cup inferiorly

1%

(36/2651)

L 1

Select Answer to see Preferred Response

SUBMIT RESPONSE 1

You have 100% on this question.
Just skip this one for now.

(OBQ06.2) During total hip arthroplasty, which of the following techniques increases range of motion prior to impingement? Review Topic

QID: 13
Type in at least one full word to see suggestions list
1

Using implants with a smaller femoral head

4%

(143/3609)

2

Using implants with a larger femoral head to neck ratio

94%

(3398/3609)

3

Using a ultra high molecular weight polyethylene liner on the acetabulum

0%

(16/3609)

4

Decreasing femoral offset

1%

(34/3609)

5

Cementing the femoral stem

0%

(3/3609)

L 1

Select Answer to see Preferred Response

SUBMIT RESPONSE 2

You have 100% on this question.
Just skip this one for now.

(OBQ05.268) A surgeon is planning to revise a left hip resurfacing component to a total hip arthroplasty. He wishes to decrease the joint reaction force of the left hip by increasing the femoral offset. Which of the following labeled measurements found in Figure A best describes femoral offset? Review Topic

QID: 1154
FIGURES:
Type in at least one full word to see suggestions list
1

Line 1

2%

(37/1574)

2

Line 2

1%

(17/1574)

3

Line 4

95%

(1499/1574)

4

Line 5

0%

(5/1574)

5

Line A

1%

(9/1574)

L 1

Select Answer to see Preferred Response

SUBMIT RESPONSE 3

You have 100% on this question.
Just skip this one for now.

(OBQ05.245) The schematic shown in Figure A displays a ceramic-on-ceramic total hip arthroplasty articulation with impingement. Which of the following modifications would increase the primary arc range of motion? Review Topic

QID: 1131
FIGURES:
Type in at least one full word to see suggestions list
1

Addition of a collar on the femoral head

1%

(16/1889)

2

Exchanging the ceramic liner with a hooded polyethylene liner

1%

(14/1889)

3

Increasing the femoral head size

93%

(1753/1889)

4

Increasing the femoral offset

3%

(65/1889)

5

Increasing the acetabular anteversion

2%

(38/1889)

L 1

Select Answer to see Preferred Response

SUBMIT RESPONSE 3

You have 100% on this question.
Just skip this one for now.

(OBQ04.269) Which of the following factors is most likely to increase the risk of hip dislocation after a total hip arthroplasty (THA)? Review Topic

QID: 1374
Type in at least one full word to see suggestions list
1

Large head-to-neck ratio

2%

(51/2664)

2

Use of a skirted femoral head

81%

(2153/2664)

3

Femoral component in 15 degrees of anteversion

3%

(84/2664)

4

Acetabular cup in 15 degrees of anteversion

3%

(77/2664)

5

Acetabular cup in 50 degrees of abduction

11%

(292/2664)

L 2

Select Answer to see Preferred Response

SUBMIT RESPONSE 2
ARTICLES (34)
Topic COMMENTS (21)
Private Note