Venous Malformation Mimicking Patellofemoral Pain Syndrome in a Young Adult With Limb Length Discrepancy.

Limb length discrepancy (LLD) can result from a variety of underlying pathologies, and the exact etiology may be challenging to identify when patients present with common musculoskeletal complaints. We present a case of LLD in a 19-year-old gentleman likely attributed to a venous malformation at the vastus medialis, with a concomitant osteochondroma of the contralateral proximal tibia. He initially presented with intermittent right-sided knee pain. An X-ray of his bilateral lower limbs revealed an osteochondroma of the contralateral proximal tibia and a 2.5-cm LLD, with the right lower limb being shorter. He was initially diagnosed with patellofemoral pain syndrome and managed conservatively. Non-response to conservative measures prompted further imaging with magnetic resonance imaging of his right knee, which revealed a venous malformation extending from the vastus medialis muscle into the pre-femoral and Hoffa's fat pad as well as the femoral trochlea. He subsequently underwent VenaSeal treatment of the venous malformation with improvement in pain. This case is unique for having two concomitant conditions that could potentially contribute to LLD. It also highlights the importance of having a broad differential list for patients presenting with LLD.