Background: Spontaneous hemarthrosis of the knee joint in the elderly population is a rare phenomenon and is mostly seen in those with osteoarthritis. The identified causes of spontaneous hemarthrosis in this demographic include subchondral bone bleeding, meniscal tear, genicular artery bleeding, and the use of anticoagulants. Hemarthrosis caused by isolated patellofemoral bleeding, as in this case series, has been rarely documented and poorly described.
Case: Three patients presented with recurrent hemarthrosis secondary to erosive patellofemoral arthritis. Recurrent hemarthrosis from the eroded patellofemoral subchondral bone has not been well described. Each patient presented with symptoms secondary to painful effusions that were identified by aspiration. Each patient was successfully treated with patellofemoral or total knee arthroplasty
Conclusion: Spontaneous or recurrent effusions in the setting of erosivepatellofemoral arthritis should prompt orthopaedic surgeons to consider hemarthrosis as the cause of such effusions. Patellofemoral or total knee arthroplasty is effective in resolving the hemarthroses, resolving pain, and restoring function in these patients
