Joint Replacement Institute

The knee joint includes the end of the thigh bone (the femur), the top of the leg bone (the tibia) and the knee cap (the patella). The weight of the body is transferred through the femur, across the knee joint, and into the tibia. There are large muscles in the front of the thigh (the quadriceps) that straighten the knee (extension). The large muscles in the back of the thigh (the hamstrings) bend the knee (flexion). The patella functions as an important lever for the quadriceps muscles, making the muscle more efficient. When you bend and straighten your knee, the surfaces of the tibia and femur roll and slide on each other and the patella moves up and down against the front of the femur. Front and side x-ray views of a normal knee are shown in Figures 1A and 1B respectively. The thigh bone (femur) is on the top and the leg bone (tibia) is on the bottom. The smaller bone in the leg is the fibula. The knee cap (patella) can be seen in the front of the knee on the side view. The apparent space between the bones is actually occupied by articular cartilage and is called the joint space. Cartilage is not dense enough to be seen on an x-ray.

The knee is a synovial joint. The tissue lining the joint, called synovium, produces fluid that lubricates and nourishes the surfaces of the joint. The important internal parts of the knee include articular cartilage, meniscal cartilage, ligaments, and tendons. There are two types of cartilage in the knee. Articular cartilage is specialized tissue that covers the ends of the bones. Meniscal cartilage is specialized tissue located around the perimeter of your knee. It helps to distribute the load and provide some stability as well as lubricate the articular cartilage. There are several ligaments (strong bands of fibrous tissue which connect bone to bone) attached to the femur and tibia, which provide stability to the knee. There are also several tendons, which are also strong bands of fibrous tissue, but they attach muscle to bone. It is the force of the quadriceps and hamstring muscles, pulling through tendons, that move the knee and enable you to walk, sit, get up from sitting, climb stairs, etc.

Unlike conventional total hip replacement (THR), hip resurfacing is conservative in that the femoral head and neck of the hip joint are not removed nor is bone removed from the femur. In the case of surface replacement, less bone is also removed from the acetabulum as compared to conventional THR since no polyethylene liner is used.

Minimally Invasive Hip Resurfacing

JRI Research

The staff of JRI is engaged in various research studies, including: improving long term joint replacement durability by selective use of new replacement bearing technology, histological characterization of implant fixation, relationship between wear debris and aseptic loosening.

Hip Replacement

Knee Replacement

Figure 1A

Figure 1B