Patellar Dislocation: Displacement of the PATELLA from the femoral groove.DislocationsPatellar Ligament: A band of fibrous tissue that attaches the apex of the PATELLA to the lower part of the tubercle of the TIBIA. The ligament is actually the caudal continuation of the common tendon of the QUADRICEPS FEMORIS. The patella is embedded in that tendon. As such, the patellar ligament can be thought of as connecting the quadriceps femoris tendon to the tibia, and therefore it is sometimes called the patellar tendon.Patella: The flat, triangular bone situated at the anterior part of the KNEE.Patellofemoral Joint: The articulation between the articular surface of the PATELLA and the patellar surface of the FEMUR.Chondromalacia Patellae: A degeneration of the ARTICULAR CARTILAGE of the PATELLA, caused by a decrease in sulfated MUCOPOLYSACCHARIDES in the ground substance. When accompanied by pain, it is sometimes considered part of or confused with PATELLOFEMORAL PAIN SYNDROME.Hip Dislocation: Displacement of the femur bone from its normal position at the HIP JOINT.Tenodesis: Fixation of the end of a tendon to a bone, often by suturing.Joint Instability: Lack of stability of a joint or joint prosthesis. Factors involved are intra-articular disease and integrity of extra-articular structures such as joint capsule, ligaments, and muscles.Fractures, Cartilage: Breaks in CARTILAGE.Shoulder Dislocation: Displacement of the HUMERUS from the SCAPULA.Knee Injuries: Injuries to the knee or the knee joint.Arthroscopy: Endoscopic examination, therapy and surgery of the joint.Knee Dislocation: Slippage of the FEMUR off the TIBIA.Knee Joint: A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.Hip Dislocation, Congenital: Congenital dislocation of the hip generally includes subluxation of the femoral head, acetabular dysplasia, and complete dislocation of the femoral head from the true acetabulum. This condition occurs in approximately 1 in 1000 live births and is more common in females than in males.Femur: The longest and largest bone of the skeleton, it is situated between the hip and the knee.Recurrence: The return of a sign, symptom, or disease after a remission.Traction: The pull on a limb or a part thereof. Skin traction (indirect traction) is applied by using a bandage to pull on the skin and fascia where light traction is required. Skeletal traction (direct traction), however, uses pins or wires inserted through bone and is attached to weights, pulleys, and ropes. (From Blauvelt & Nelson, A Manual of Orthopaedic Terminology, 5th ed)Lens Subluxation: Incomplete rupture of the zonule with the displaced lens remaining behind the pupil. In dislocation, or complete rupture, the lens is displaced forward into the anterior chamber or backward into the vitreous body. When congenital, this condition is known as ECTOPIA LENTIS.Acromioclavicular Joint: The gliding joint formed by the outer extremity of the CLAVICLE and the inner margin of the acromion process of the SCAPULA.