Planning

IndicationsRevision TKR

 

Aseptic loosening

Infection

Instability

Wear & breakage components

Fracture

Stiffness 

Pain

 

Aims

 

Restoration of anatomical alignment

Restoration of joint line

Restoration of bone stock

Restoration of femoral and tibial rotation

Flexion and extension balancing

 

Surgical Issues

 

1.  Exclude Infection

2.  Incisions / Approach

3.  Component removal

4.  Bone Defects 

5.  Restoration of joint line

6.  Balancing

7.  Component Fixation / Stems 

8.  Constraint

9.  Patella

 

Examination

 

Lower limb

- old incisions

- pulses

- sensation (Charcot neuropathy)

 

ROM 

- need 110o flexion to remove and insert components

- otherwise will need tibial tubercle osteotomy

 

Stability

- LCL / MCL intact

- need VVC / hinge

 

Extensor Mechanism

 

Examine hip and back

- may be cause of referred pain

 

Exclude Infection

 

1.  Clinical Findings

2.  ESR & CRP

3.  Bone Scan

4.  Aspiration 

5.  Intra-op FFS

 

Assess Bone Stock

 

Causes

- secondary to osteolysis 

- iatrogenic when removing components

 

Site

 

Tibial bone loss

- often medial, due to implant in varus

 

Femoral bone loss

- often posterior femoral condyles

 

Aims

 

Preserve all viable bone

Reconstruct deficient bone

Provide stable base for implants

 

AORI Classification / Andersen Orthopaedic Research Institution

 

T Tibial F Femoral

 

1 Contained Metaphyseal defect 

 

2 Damaged Metaphysis

A One condyle

B Both

 

3 Deficient Metaphysis +/- collaterals / quadriceps

 

Template

 

1.  Establishment of joint line essential

 

Allows flexion and extension balancing

 

X-ray contralateral knee

- measure medial epicondyle to joint line

 

Template same on revision knee

 

2.  Length and diameter of stems

 

3.  Augments

- distal and posterior femur

- proximal tibia

 

Order instrumentation

 

Previous component company specific removal gear

Cement removal instruments

Diaphyseal engaging stems, offset available

Modular metal augments

Constraint including CCK / hinges

Full component of poly thicknesses

Allograft