Unilateral absence of round ligament of femur - Cadaveric case report

Round ligament of femur is a pyramidal structure with apex attached to the fovea of the femoral head and its base blends with the transverse acetabular ligament. It is an intracapsular but extrasynovial structure. It is also called ligamentum teres femoris or foveal ligament. It transmits the acetabular branch of obturator artery and also acts as a secondary stabilizer of the hip joint by supplementing the other ligaments of the hip joint in extreme range of motion. Absence of round ligament of femur is a rare variation which can be unilateral or bilateral and prevalence is 2%–3%. It presents rarely as isolated entity or in association with congenital dysplasia of the hip. This report presents a rare variation of unilateral absence of round ligament of femur with minimal evidence of developmental dysplasia of the hip. During routine dissection of a middle-aged cadaver, on opening the hip joint cavity, the round ligament of femur was absent on the left side whereas, acetabular labrum and femoral head were normal. On the right side, the lower limb was normal in position and round ligament of femur was present in normal length and thickness. Awareness and knowledge of such a rare variation are important for radiologists and orthopedicians for better diagnosis and management of hip-related problems.