Pes anserinus

The pes anserinus is the conjoined tendinous insertion of the sartorius, gracilis, and semitendinosus muscles onto the anteromedial surface of the proximal tibia. As these tendons converge on the upper medial tibia, they form a broad aponeurotic sheet whose configuration resembles the webbed foot of a goose, giving rise to the name 'pes anserinus'.

Deep to pes anserinus lies the superficial part of the medial (tibial) collateral ligament of the knee, which may partially fuse with it. A pes anserine bursa is interposed between the tendons and the medial collateral ligament, helping reduce friction during knee motion.

The pes anserinus exhibits significant morphological diversity. Olewnik et al. described three primary insertion patterns: short, band-shaped, and fan-shaped. [1]

• Short Insertion  – a compact, localized insertion on the medial tibia.

• Band-shaped Insertion – an elongated, narrow tendinous band.

• Fan-shaped Insertion – a broad, widely spread tendinous attachment resembling a fan.

Clinical correlate: Pes anserine bursitis (Anserine syndrome)

• Inflammation of the bursa located between the pes anserinus tendons and the medial collateral ligament.

• Produces pain and tenderness approximately 4–5 cm below the medial knee joint line.

• More common in runners, obese women, and patients with osteoarthritis.