The proximal tibia (closest to the upper leg) is shaped to form a joint with the fibula at the patella (kneecap) called the superior tibiofibular joint. This joint articulates with the femur at the patella (kneecap) and supports weight -bearing for the rest of the body.
The distal tibia (inferior tibiofibular joint) forms a joint with the fibula at the ankle. This articulation of the tibia with the fibula is called the inferior tibiofibular joint. The tibia and fibula also forms another joint at the ankle with the talus (ankle bone). This ankle joint of the tibia and talus is one of the stronger weight-bearing structures compared to the joint formed at the ankle with the fibula and the talus.
The knee, ankle, superior, and inferior articulations of the tibia combine to make four joints formed by the tibia with other bones. The tibia is structured to be the strongest weight -bearing bone in the body. The tibia is found next to the fibula and is connected to it at the knee joint forming what is called the syndesmotic joint of the superior tibiofibular joint or the proximal tibiofibular articulation.
The word syndesmosis is a noun which describes the anatomy of a type of joint that is bound together by ligaments and other cartilaginous or fibrous tissue. The ending of the word “ osis “means condition of in medical terminology. The Greek meaning of the root word, “synde” s. combines with the ending “osis” and is used with the Greek root word “syndein” which means to bind together. This combination of a root word and ending, is used to describe this type of joint called a syndesmotic (an adjective of syndesmosis) joint.
This type of joint has very little movement and is structured to add the weight-bearing component of the tibia and fibula for the upper body support it needs to be in motion or at rest in an upright position of a person standing, walking, running or jumping. The knees act like a shock absorber for the rest of the body when it is in motion. This is why there must be anatomically structured strong joints at the knees to support the weight of the rest of the body without breaking the joints.
Anatomy of the Tibia:
The tibia is categorized as a long bone which is composed of a diaphysis and two epiphyses.
The diaphysis is the midsection of the tibia known as the shaft or body.
The epiphyses are the two rounded extremities of the tibia bone.
The upper extremity has its’ position closest to the thigh and is known as the superior or proximal extremity.
The lower extremity of the tibia is known as the inferior or distal extremity and is closest to the foot.
The tibia is most contracted in the lower third of the body (shaft).
The distal (lower) extremity is smaller than the proximal (upper) extremity.
The proximal extremity expands in the transverse plane with the medial and lateral condyle (the rounded surface at the end of a bone). The medial and lateral condyles are separated by the intercondylar area. This is where the cruciate (having across-like shape) ligaments and meniscus (a crescent-shaped disk of cartilage) attach. The meniscal and cruciate ligaments are present in the knee joint of this intercondylar area. The cruciate ligaments are two large ligaments called the anterior and posterior which criss-cross in the knee joint to provide stability. There are four joints formed by the tibia called the tibiofemoral components of the knee joint, the talocrural joint (ankle), the superior and inferior tibiofibular joints. This completes the list of the four joints formed by the tibia.