Arthrodesis Conversion

 

Hip arthrodesisFusion conversion

 

Indications

 

Severe lower back pain - most common indication

Ipsilateral knee pain

Contralateral hip pain

Malposition - especially abduction

 

Fusion

Degenerative scoliosis post hip arthrodesis

 

Issues

 

Abductors

- if intact will have atrophied

- risk of abnormal gait / trendelenberg gait post surgery

 

Leg length discrepancy

 

Complex surgery

- restore anatomical hip center

- significant complications

 

Examination

 

LLD

- difficult to assess given flexed position of hip

 

Assessment abductor function

- palpation whilst asking patient to contract

- MRI

 

Technique

 

Surgical technique PDF Hip Conversion Robotic Assistance

 

Surgical technique PDF Hip Conversion image less navigation

 

Youtube surgical technique Hip Conversion image less navigation

 

Difficulty prepping & draping

 

Exposure

- identify and protect sciatic nerve

- perform GT osteotomy / trochanteric slide

- may require adductor & psoas tenotomy

 

Neck osteotomy

- can be difficult to identify landmarks

- can damage acetabulum with saw

 

Identification of acetabulum and restoration of anatomical hip center

- normal landmarks not identifiable

- need to establish correct position and depth

- have to ream away femoral head

- consider image less navigation / CT guidance / robotic guidance

 

Restoration of leg length

- maximum 4cm lengthening

 

Hip Fusion 2Hip Fusion THR 2

 

Hip arthrodesisFusion conversionHip fusion conversion 2

 

Results

 

Survival

 

Joshi et al JBJS Am 2002

- 208 hips converted at average 51 years

- 83% good to excellent function

- 96% 10 year survival

- 90% 15 year survival

- 15 nerve palsies

 

Outcomes

 

Flecher et al Int Orthop 2018

- fusion takedown in 23 hips with 15 year follow up

- average improvement in Harris hip score 30 points

- average hip ROM 30 degrees

- back pain decreased in 62%

- knee pain decreased in 42%

 

Complications

 

Jauregui et al Int Orthop 2017

- systematic review of 27 studies and 1,100 conversions fusion to THA
- infection 5%

- instability 3%

- loosening 6%

- nerve injury 5%

- abductor complications 13%

 

Ayekoloye et al Bone Joint J 2021

- 39 hip fusion conversion to THA

- 70% required walking aid postoperatively

- 5% sciatic nerve injury

- 10% had significant HO required excision