TKA – Approach to Patellar Loosening
Factors Associated with Patellar Loosening
1. Cementing into shitty bone 5. Failure of bone ingrowth
2. Component malposition 6. Asymmetric bone resection
3. Patellar instability 7. Loosening of other components
4. Osteonecrosis 8. Metal backing (bad all around!)
– patellar wear is common, but loosening is uncommon, reportedly in 1-2% of cases
– metal backing sucked. Failure of bone ingrowth, delamination, rapid poly wear, metal on metal fretting.
– if symptomatic, they should have it revised
– consider the etiology of the loosening – if there is patellar instability secondary to femoral or tibial malalignment, just revising the patella will not be good enough. You need to revise it all
– the optimal solution for the patella is to remove the component, re-prepare the host bone, and re-implant a new one
– if remaining bone stock is unsatisfactory, you may be forced to just take out the patellar prosthesis, smooth down the bone as best as possible, and leave it articulating with the prosthesis (patellar arthroplasty). Alternatively, do a patellectomy.