Management of Patella Fractures after TKA
Patella fractures are a rare complication of total knee arthroplasty. A thorough evaluation of the nature and cause of each fracture is essential in determining the optimal management strategy.
Periprosthetic patella fractures are relatively rare, occurring in less than 1% of total knee arthroplasty (TKA) cases. They are more common post-operatively than intra-operatively; they are also more common with revision TKA than primary TKA. At ICJR’s Philadelphia Revision Course, Neil Sheth, MD, from the University of Pennsylvania, outlined his strategy for evaluating and managing these fractures.
Dr. Sheth starts the diagnostic workup by taking a history and performing a physical exam. Symptoms pointing to a possible fracture include:
- Anterior knee pain
- Tenderness to palpation
- Joint effusion
- Extensor weakness/lag
- Patellar instability
- Inability to negotiate stairs
To confirm the presence of a fracture, Dr. Sheth orders AP, lateral, and merchant or skyline view x-rays. If the x-rays are inconclusive, Dr. Sheth may order a bone scan. These scans can differentiate a new fracture from an old fracture, but have the drawback of remaining positive for up to 2 years after a fracture.
The presence of predisposing factors should also be evaluated to help establish the diagnosis, including:
- Direct or indirect trauma
- Anatomic factors (patellar thickness, osteonecrosis)
- Technical factors (osteolysis and component loosening, overstuffing of the patella, malalignment)
- Patient factors (osteoporosis, poor bone stock, inflammatory arthropathy)
- Implant design factors (central peg design, metal-backed component)
After the fracture is diagnosed, it should be classified. Three factors are used in classification:
- Nature of the fracture (location, pattern, fragment displacement)
- Stability (stability of the patella, integrity of the extensor mechanism)
- Biology of the existing bone (quality, vascularity)
The classification system proposed by Ortignera and Berry differentiates fractures into type I, II, and III categories, with type III being the most severe.
When a fracture has been diagnosed and classified, various treatment options should be considered:
- Non-operative treatment
- Open reduction and internal fixation
- Partial or total patellectomy
- Revision TKA or revision of individual patella components
- Extensor allograft reconstruction
In general, type I fractures do not require revision surgery, while types II and III fractures may require an operation. Overall, because operative treatment often leads to complications and re-operation, Dr. Sheth prefers non-operative treatment, especially if the implant is stable and the extensor mechanism is intact.
Dr. Sheth’s presentation can be found here.