Unhappy triad posterior translation of the tibia on the femur. The classic O'Donoghue triad is characterized by an injury to three knee structures (in order): The anterior cruciate ligament is one of the four crucial ligaments in the knee. It originates from the lateral condyle of the femur and goes to the intercondyloid eminence of the tibia. Its function is to provide stability in the knee and minimize stress across the knee joint. It also restrains excessive forward movement in the leg and limits rotational movements in the knee. Injury An anterior cruciate ligament injury results from excess tension on the ligament.
Medial knee injuries adductor tubercle. The sMCL connects the femur to the tibia. It originates just proximal and posterior to the medial epicondyle (not directly on the epicondyle) and splits into two distinct sections. One tibial section attaches to soft tissue, 1 cm distal to the joint line. The other tibial section attaches directly to the tibia, anterior to the posteromedial tibial crest, 6 cm distal to the joint line. This distal attachment is the stronger of the two and makes up the floor of the pes anserine bursa. The proximal tibial attachment of the sMCL is the primary stabilizer to valgus force