The bones of each lower limb consist of a femur, a patella, a tibia, a fibula, tarsal bones, metatarsals, and phalanges.
The femur, or thigh bone, is the largest and strongest bone of the body. Structures at the proximal end include the rounded head, a short neck, and two large processes that are sites of muscle attachment: a superior, lateral greater trochanter (tro-kan’-ter) and an inferior, medial lesser trochanter. The head of the femur fits into the acetabulum of the coxal bone. The neck is a common site of fractures in older people. At the enlarged distal end are the fateral and medial condyles, surfaces that articulate with the tibia.
The patella, or kneecap, is located anterior to the knee joint. It is embedded in the tendon of the quadriceps femoris, which extends over the anterior of the knee to insert on the tibia. The patella offers protection to the structures within the knee joint during movement.
The tibia, or shinbone, is the larger of the two bones of the leg. It bears the weight of the body. Its enlarged proximal portion consists of the fateral and medial condyles, which articulate with the femur to form the knee joint. The tibial tuberosity, a roughened area on the anterior surface just distal to the condyles, is the attachment site for the patellar ligament. The distal end of the tibia articulates with the talus, a tarsal bone, and laterally with the fibula. The medial malleolus (mah-le-o ‘-lus) forms the medial prominence of the ankle.
The fibula is the slender, lateral bone in the leg. Both ends of the bone are enlarged. The proximal head articulates with the lateral surface of the tibia but is not involved in forming the knee joint. The distal end articulates with the tibia and talus. The lateral malleolus forms the lateral prominence of the ankle.
Tarsal Bones, Metatarsals, And Phalanges
The skeleton of the foot consists of the tarsal bones (ankle), metatarsals (instep), and phalanges (toes). Seven bones compose the tarsal bones. The most prominent tarsal bones are the talus, which articulates with the tibia and fibula, and the calcaneus (kal-ka’n-e-us), or heel bone. Five metatarsals support the instep. They are numbered I to V, starting with the metatarsal adjacent to the great toe. The tarsal bones and metatarsals are bound together by ligaments to form strong, resilient arches of the foot. Each toe consists of three phalanges (proximal, middle, and distal), except for the great toe, which has only two (proximal and distal).
Total hip replacement (THR) has become commonplace among older persons as a way to overcome the pain and immobility caused by osteoarthritis of the hip joint. This procedure utilizes two prosthe- ses. A polyurethane cup replaces the damaged acetabulum, and a metal shaft and ball replace the diseased head of the femur. Surfaces of the pros- theses in contact with bone are porous, allowing bone to grow into them to ensure a firm attachment. Patient recovery involves stabilization of the prostheses while bone grows into them as well as normal healing from the surgery.