arthrodesis of the knee

indications

·      most commonly performed for

·      infectious arthritis

·      failed TKR

·      tumours treated by resection-arthrodesis

·      monoarticular arthritis in young active patients

·      neuropathic joint disease

·      congenital dysgensis of femur

technique
Compression technique

·      anterior longitudinal incision

·      medial parapatellar arthrotomy

·      patella excised

·      TKR jigs used to make appropriate bony cuts

·      10o flexion

·      7o valgus

·      5o external rotation

·      aim to resect only 1-2 mm

·      cut tibia at 90o and then femur to give desired valgus

·      ideal fixation device is

·      bilateral

·      biplanar

·      first construct bilateral frame in coronal plane

·      can use Charnley clamp

·      2 transverse Steinmann pins

·      alternatively use AO external fixator

·      three femoral and three tibial transfixion pins from medial to lateral

·      bar on each side

·      then add unilateral frame in sagittal plane

·      two femoral and two tibial pins anteriorly

·      anterior bar

·      attach to frame (tent frame)

·      bone graft

·      if less than 50o apposition

·      may use patella

·      fixation remains for 12 weeks then cylinder cast

Intramedullary technique

·      preoperative assessment

·      full-length AP and lateral x-rays with magnification marker

·      determine length and diameter of nail

·      similar preparation

·      bone cuts need to be made to accommodate nail

·      minimal flexion and valgus

·      guide wire passed down tibia

·      reamed until cortical bone encountered

·      trochanteric fossa exposed routinely

·      guide wire passed and femur reamed

·      ream to size determined in tibia

·      insert nail antegrade from greater trochanter across knee to distal tibia

·      lock nail distally

·      proximally if rotationally unstable