Causes of patellofemoral pain syndrome
In reality, although the pain is experienced in the front of the knee, the underlying cause may be remote - such as a hip problem or a bony rotation in the hip or thigh, or even a structural problem in the foot and ankle.
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Patellofemoral pain syndrome in female athletes: A review of diagnoses, etiology and treatment options. Molly Vora,1 Emily Curry,2 Amanda Chipman,3 Elizabeth Matzkin,4 and Xinning Li1 Orthop Rev (Pavia). 2017 Dec 14; 9(4): 7281.
Patellofemoral pain in athletes: clinical perspectives. Halabchi F, Abolhasani M, Mirshahi M and Alizadeh Z. Open Access J Sports Med. 2017; 8: 189–203.