TKA – Approach to Patellar Failure
Factors Associated with Patellar Failure
1. Metal Backing – #1 cause 5. Increased Postop Flexion
2. Patellar Instability 6. Increased Patellar Thickness – increases jt reaction forces
3. Elevation of Joint Line
4. Asymmetric Patellar Cut
– the first thing to decide is whether the whole thing needs to be revised – ie. what was the cause of patellar failure? If you do not address this, the patella will inevitably fail again. Be prepared to revise it all.
– revising a patella can be very difficult – there may not be much bone left to secure another prosthesis
– if sufficient bone stock is left – great, revise the component
– if insufficient bone stock is left – consider patellaplasty or patellectomy; resist the temptation to resurface an inadequate patella
– if revising a metal backed patella – you must do a thorough debridement of all the metallosis. Also, inspect the femoral surface for wear from the metal backing on the patella.