PFA shares many complications with TKA, including persistent pain, arthrofibrosis and polyethylene wear. Some early complications are more common in PFA, such as persistent anterior knee pain, intraoperative fracture, and extensor mechanism failure [10,11]. There are also documented complications specific to PFA that do not seem to appear after TKA, such as the presence of a hematoma in the lateral compartment and incorrect extensor mechanism alignment . The most common cause of PFA failure is the progression of osteoarthritis resulting in conversion to TKA, accounting for approximately 25% of revisions at 15 years [12,13]. However, while AVN of the patella leading to patellar fracture and button loosening are known complications of TKA, no mentions of this complication were found during our literature review. This may be in part due to the fewer number of PFAs performed relative to TKAs. Since many patients with persistent pain after PFA will eventually undergo TKA, this complication may be not be reported due to revision secondary to another complication. Additionally, PFA is less commonly associated with a lateral release, which has been shown to have greater implication in patellar AVN. Our patient is unique in that she developed clear radiologic evidence of AVN of the patella in the absence of a lateral release during a PFA. Initially, she appeared to be progressively healing. Despite early success after PFA, the patient developed AVN at 4 months that was radiologically appreciable.
AVN of the patella is a complication that can result after PFA. Even in the absence of a lateral release, damage to the surrounding vasculature during this procedure can be significant enough to disrupt critical blood supply. Continual anterior knee pain after a PFA should raise suspicion for this complication.
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