Lateral patellar plica

Lateral patellar plica is a rare synovial fold within the knee joint, typically considered an embryonic remnant of the mesenchymal septa that incompletely resorbs during fetal development. It is found on the lateral aspect of the patella and appears as a thin band or ridge of synovial tissue, present in approximately 1–3% of knees based on arthroscopic and anatomical studies. Unlike the more commonly symptomatic medial plica, the lateral patellar plica is infrequently implicated in clinical pathology and is usually asymptomatic. Histologically, it consists of a synovial layer, a collagenous layer, and an underlying adipose or areolar tissue, forming part of the synovial tissue complex that surrounds the patella.