Hip Arthrodesis

Question 1

What are the biomechanics of a hip arthrodesis?

Answer 1

• Reduces efficiency of gait by approx 50%
• increases pelvic rotation of contralateral hip
• increases stress at adjacent joints
• biochemistry
  
  • increases 02 consumption
  • requires 30% more energy expenditure for ambulation

Question 2

What is the prognosis of a hip arthrodesis?

Answer 2

• Provides pain relief and resonable clinical results in most patients
• sucessmaybe limited by adjacent joint degeneration in 60% of patients
• lumbar spine/ipsilateral knee or contralateral hip maybe effected
• low back pain and arthritic ipislateral knee pain are the most common symptoms
  
  • may start within 25 years of hip arthrodesis

Question 3

What are the indications for hip arthrodesis?

Answer 3

• Salvage for failed THR- most common
• Young active labourer with painful unilateral ankylosis after infection or trauma
• neuropathic arthropathy
• tumour resection

Question 4

What are the contraindications for hip arthrodesis?

Answer 4

• Active infection
• Severe LLD >2.0 cm
• bilateral hip arthritis
• adj joint degenerative changes
  
  • lumabr spine
  • contralateral hip
  • ipsilateral knee
• severe osteoporosis
• degenerative changes in lumbar spine
• contralateral THR
  
  • increase failure rate 40% in THR when contralteral hip arthrodesis

Question 5

What are the indications for conversion of fusion to THR?

Answer 5

• Severe disabilitating back pain- most common
• severe ipsilateral knee pain with instability
• severe contralateral knee pain

Question 6

What investigaiton should be ordered before considering a conversion fusion to THR?

Answer 6

• EMG to assess the status of the gluteus medius
  
  • a constrained acetabular component is required if abductor complex is nonfunctional

Question 7

What are the outcomes of conversion fusion to THR?

Answer 7

• Clinical outcome is dependent on abductor complex function
• the presence of hip abductor complex weakness or dysfunction requires prolonged rehab/ severe lurching gait may develop

Question 8

Describe the goals of hip arthrodesis and the optimal position for fusion?

Answer 8

• Goals
  
  • achieve apposition of arthrodesis surfaces/ obtain rigid internal fixation and promote early mobilisation
• optimial positiion
  
  • 20-35^o Flexion
  • 0-5^o adduction
  • 5-10^o ER
  • avoid abduction as it creates pelvic obliquity and increased back pain

Question 9

Describe the approach for hip arthrodesis?

Answer 9

• Lateral approach with trochanteric osteotomy
  
  • important to preserve abductor complex
  • avoid injury to superior gluteal nerve
  • use cobra plating or screw fixation

Question 10

What are the complications for hip arthrodesis?

Answer 10

• Low back pain
  
  • improved by taking down arthrodesis
  • but overall improvement depends on abductor function
  • ipislateral knee degeneration and laxity
  • contralateral hip degeneration