Like elbow arthrodesis, knee arthrodesis is an option of last resort



- cannot sit on airplane toilet with door closed




Coapt 2 coplanar cancellous surfaces under compression with rigid fixation




Septic arthritis

Salvage failed TKR / infected TKR


Charcot Join





Bilateral knee fusion

Ipsilateral hip fusion




Fusion rates

- can be difficult to obtain fusion


Difficulties mobilising

- give patient trial in cylinder cast




Short leg

- fuse straight 


Normal length

- in 10° for swing through


Valgus 5 - 7o


External rotation 5 - 10o




1.  External fixator

2.  IMN

3.  Double plating




Mabry et al Clin Orthop Related Research 2007

- arthrodesis for infected TKR

- union in 41 / 61 patients treated with external fixation, deep infection rate 4.9%

- union in 23/24 patients treated with IMN, deep infection rate 8.9%


1.  External Fixation


Knee Fusion External Fixation



- simpler

- less blood loss

- better in infection



- pin tract infection, loosening




Anterior longitudinal incision

- medial parapatellar arthrotomy

- patella excised


Bony cuts 

- use TKR jigs 

- aim to resect only 1-2 mm

- cut tibia at 90° 

- cut femur 10° flexion or 0° if short / 7° valgus / 5° ER


Bilateral & Biplanar external fixator


First construct bilateral frame in coronal plane

- 3 femoral & 3 tibial transfixion pins from medial to lateral

- bar on each side


Then add unilateral frame in sagittal plane

- 2 femoral & 2 tibial 1/2 pins anteriorly

- anterior bar


Circular frame



- allows compression and weight bearing

- post operative alignment adjustment


Bone graft


If less than 50% apposition

- may use patella


Fixation remains for 12/52


2.  IMN




A.  Long fusion nail S & N / Stryker

B.  Wichita nail / Stryker / Modular nail


Pre-operative assessment


Full-length AP & Lat XR with magnification marker

- determine length & diameter of nail


1.  Long fusion nail



- different IM canal size between tibia and femur


Radio-lucent table

- drape to pelvis

- sand bag under hip


Medial parapatella approach to knee

- bone cut made


Guide wire passed down tibia

- reamed until cortical bone encountered


Trochanteric fossa exposed routinely

- guide wire passed & femur reamed

- ream to size determined in tibia


Insert nail antegrade from GT across knee to distal tibia

- nail should bend concave laterally to recreate anatomical alignment & slight flex


Should not end in diaphyseal portion of either bone 

- risk of stress fracture


Lock nail distally but not proximally

- proximally if rotationally unstable


2.  Wichita nail / Modular nails



- tibial and femoral components insert via knee & then join together

- different sizes for femur and tibia

- single knee incision



- very difficult to remove after fusion