This retrospective study from Mayo Clinic reviewed 85 post-TKA patellar fractures across 12,464 consecutive arthroplasties. The authors developed a three-type classification based on extensor mechanism integrity, implant fixation status, and remaining bone stock. The study defines which fracture types can be observed and which require surgery — and quantifies how poorly operative treatment performs.
When you see a patellar fracture on a post-TKA radiograph, the single most important question is: is the extensor mechanism intact and is the implant well-fixed? If the answer to both is yes (Type I), treat nonoperatively. This paper documents a 3% operative conversion rate and 82% pain-free outcome with observation alone.
If the extensor mechanism is disrupted (Type II) or the implant is loose (Type III), surgery is often needed — but counsel the patient carefully. Type II carries a 50% complication rate, and Type III leaves more than half of patients symptomatic at follow-up regardless of what you do.
For Type IIIb (loose implant, thin or comminuted bone), do not attempt fixation. Remove the implant and perform partial or complete patellectomy. The bone cannot support reconstruction. This paper established the classification framework that guides TKA patellar fracture management in ROCK and standard arthroplasty curricula. Know the three types and their treatment defaults cold.
This retrospective study from Mayo Clinic reviewed 85 post-TKA patellar fractures across 12,464 consecutive arthroplasties. The authors developed a three-type classification based on extensor mechanism integrity, implant fixation status, and remaining bone stock. The study defines which fracture types can be observed and which require surgery — and quantifies how poorly operative treatment performs.
When you see a patellar fracture on a post-TKA radiograph, the single most important question is: is the extensor mechanism intact and is the implant well-fixed? If the answer to both is yes (Type I), treat nonoperatively. This paper documents a 3% operative conversion rate and 82% pain-free outcome with observation alone.
If the extensor mechanism is disrupted (Type II) or the implant is loose (Type III), surgery is often needed — but counsel the patient carefully. Type II carries a 50% complication rate, and Type III leaves more than half of patients symptomatic at follow-up regardless of what you do.
For Type IIIb (loose implant, thin or comminuted bone), do not attempt fixation. Remove the implant and perform partial or complete patellectomy. The bone cannot support reconstruction. This paper established the classification framework that guides TKA patellar fracture management in ROCK and standard arthroplasty curricula. Know the three types and their treatment defaults cold.