Arthrodesis

IndicationsHip Fusion

 

Young adult 

- 16 - 30 years old

- monoarticular disease

- heavy demand 

 

Exhausted options of osteotomy

- risk of THA failure  / multiple revision surgeries considered too high

 

Aims of arthrodesis

 

Maximise bony contact

Minimise shortening

Provide rigid internal fixation

Compress the fusion site

Facilitate future conversion to THR

 

Contraindications

 

AVN

- difficulties in obtaining arthrodesis without femoral bone stock

 

Poor bone stock due other causes

 

Bilateral hip disease

- need ROM in other hip 90o

- in order to compensate in gait

 

Polyarticular disease eg Rheumatoid arthritis

- likely to develop hip / knee / back OA

 

Degenerative disc disease

- lumbar spine ROM important to compensate in gait and ability to sit in chair

 

Stiff ipsilateral knee or contralateral hip 

 

Advantages

 

Good pain relief

 

No activity restriction

- most patients employed

- can return to normal jobs, even heavy labour

- most able to walk > 1 mile

 

Long term solution c.f. THA

 

Disadvantages

 

Functionally inferior to THA

 

Increased stress on other joints

 

1.  Lumbar spine 

- 50% back pain

- most common reason for converting to THR

 

2.  Ipsilateral knee 

- 50% knee pain and instability

- increase rotation demanded in knee due to arthrodesis

 

3.  Contralateral hip

- has to compensate with increased ROM

- may predispose to OA

- will certainly worsen any underlying arthritis

 

Difficulties with certain activities

 

Squatting

Supine sex

Running

Sitting erect in chair

Difficulty putting on shoes

 

Gait abnormalities

 

Increased energy requirements

- increased oxygen consumption

- gait 50% less efficient

 

Increased lumbar lordosis to compensate 

- decreases stride length

- shortened stance phase

- contralateral hip has increased mobility compared to normal

 

Surgery

 

Concepts

 

To retain option of conversion to THR 

- don't use pelvic osteotomy

- preserve abductors

 

Types

 

1.  Intra-articular

- most common

- allows disease to be addressed

- better correction of deformity

- difficult in paediatrics due to large amount of cartilage present

 

2.  Extra-articular

 

3.  Combined

- usually use combination 

 

Position

 

Sagittal / 25° flexion

- <20° flexion - difficult to sit

- >25° flexion - difficult to walk due to LLD

 

Coronal / 5° adduction

- never abduction: can't walk, fall over even with 5° abduction

- too much adduction: LLD

 

Rotation / 15° ER 

 

< 2 cm LLD

 

Complications

 

Pseudarthrosis - 10% 

Mal-positioning

 

Methods to Increase Union

 

1.  Inter-trochanteric / subtrochanteric osteotomy 

- can increase union rate by decreasing lever arm of abductors

- come back 6/52 later and fix intertrochanteric fracture

 

2.  Vascularised bony extra-articular method

- iliac crest with Tensor Fascia Lata still attached

- the graft is inserted into trough in the anterior joint

 

Options

 

1.  Lateral cobra plate

- detach GT

- pelvis to femur

- nil pelvis osteotomy

 

Hip Fusion Cobra Plate

 

2.  DHS

- Sunderland method

 

Hip Fusion APHip Fusion Lateral 2

 

3.  Anterior plating

- Smith Peterson approach

 

4.  Double plating

- anterior and lateral plate

 

Sunderland Method

 

Intra-articular approach /  2 hole DHS

 

Technique

 

Radiolucent table with II

- supine

 

Smith Peterson approach

- leave abductors intact

- dislocate hip anteriorly

- between sartorius and TFL

- between G medius and Rectus Femoris

- take off reflected head

 

Remove cartilage from head & acetabulum

- cup arthroplasty instruments useful

- approximate raw surfaces

- pack cancellous autograft

- position hip & hold with guide-wires temporarily

- place one guide wire central in head

 

Check position of hip

- need to be able to do intra-operative Thomas test

- FFD 25o / Add 5o / ER 15o

 

Fix with 150° DHS

- through joint into thick supra-acetabular area of ilium

- supplement with additional screws as necessary

- +/- Sub-Trochanteric Osteotomy

 

Spica at 2/52 for final position 

- NWB until xray union union

 

Schneider Technique 

 

Previously very popular technique

- don't use now as THR conversion not possible 

 

Characterised by pelvic osteotomy

- increases surface area for fusion

- pelvic osteotomy compromises future THR conversion

 

Femoral head compressed into osteotomised pelvis

- Lateral Cobra plate fixed to pelvis

 

Kostuik

 

Lack of head technique

- for post AVN or failed THR

- using a lateral Cobra plate & inserting the neck into the acetabulum

 

Lateral approach with GT osteotomy

- reflect abductors cephalad

- denude acetabular cartilage

- apply lateral cobra plate

- fix the GT to the arthrodesis with screws and place graft at the site

- +/- anterior plate

 

Britian Technique 

 

Extra-articular arthrodesis

- ischio-femoral arthrodesis

- oblique subtrochanteric osteotomy

- place tibial cortical graft from inferior femur to osteotomy in ischium

- medialize femur on graft

- spica

 

Results of Arthrodesis

 

Sponseller JBJS 1984 (classic report)

 

53 patients at 20 years post fusion

- average age 14 years

- back pain 60% / similar incidence back pain to general POP

- ipsilateral knee pain 40%

- contralateral hip 20%

- pain was unrelated to length of arthrodesis

- high functional abilities / played sport

- knee laxity of MCL was common 2° to hip excesssive adduction in fusion

- 15% conversion to THR (for back or knee pain)

 

TKR with fused Hip

 

Technically difficult

- have knee over edge of bed

- only way to get high flexion of knee for insertion tibial prosthesis

 

Poor results

- poor ROM

 

Best to revise arthrodesis first

- not if abductors not functioning

 

Conversion to THR

 

Indication 

- back pain main indication

- ipsilateral knee pain

- contralateral hip pain 

 

Issues

 

1. Abductors 

- adequate function related to good outcome

- test by palpation preoperatively

 

2. Reason for fusion ?infection

 

3. Bony loss at acetabulum & femur

 

4. LLD

- average 2cm

 

5. Skin

 

6.  Higher failure than 1° THR

 

Results

 

Good relief of LBP

- less so hip and knee

- most patients happy

- hip scores change little (owing to good results from arthrodesis)

 

LL equality achieved

 

Improved ROM

 

Gait poor for a couple of years

- related to abductor function

- intensive physio required

 

Survival

- 80% 10 year

- increased risk of infection