Knee Joint: A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.Knee: A region of the lower extremity immediately surrounding and including the KNEE JOINT.Osteoarthritis, Knee: Noninflammatory degenerative disease of the knee joint consisting of three large categories: conditions that block normal synchronous movement, conditions that produce abnormal pathways of motion, and conditions that cause stress concentration resulting in changes to articular cartilage. (Crenshaw, Campbell's Operative Orthopaedics, 8th ed, p2019)Arthroplasty, Replacement, Knee: Replacement of the knee joint.Knee Prosthesis: Replacement for a knee joint.Knee Injuries: Injuries to the knee or the knee joint.Range of Motion, Articular: The distance and direction to which a bone joint can be extended. Range of motion is a function of the condition of the joints, muscles, and connective tissues involved. Joint flexibility can be improved through appropriate MUSCLE STRETCHING EXERCISES.Knee Dislocation: Slippage of the FEMUR off the TIBIA.Patella: The flat, triangular bone situated at the anterior part of the KNEE.Anterior Cruciate Ligament: A strong ligament of the knee that originates from the posteromedial portion of the lateral condyle of the femur, passes anteriorly and inferiorly between the condyles, and attaches to the depression in front of the intercondylar eminence of the tibia.Tibia: The second longest bone of the skeleton. It is located on the medial side of the lower leg, articulating with the FIBULA laterally, the TALUS distally, and the FEMUR proximally.Menisci, Tibial: The interarticular fibrocartilages of the superior surface of the tibia.Medial Collateral Ligament, Knee: The ligament that travels from the medial epicondyle of the FEMUR to the medial margin and medial surface of the TIBIA. The medial meniscus is attached to its deep surface.Arthralgia: Pain in the joint.Cartilage, Articular: A protective layer of firm, flexible cartilage over the articulating ends of bones. It provides a smooth surface for joint movement, protecting the ends of long bones from wear at points of contact.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Weight-Bearing: The physical state of supporting an applied load. This often refers to the weight-bearing bones or joints that support the body's weight, especially those in the spine, hip, knee, and foot.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.Arthroscopy: Endoscopic examination, therapy and surgery of the joint.Osteoarthritis: A progressive, degenerative joint disease, the most common form of arthritis, especially in older persons. The disease is thought to result not from the aging process but from biochemical changes and biomechanical stresses affecting articular cartilage. In the foreign literature it is often called osteoarthrosis deformans.Bone Malalignment: Displacement of bones out of line in relation to joints. It may be congenital or traumatic in origin.Posterior Cruciate Ligament: A strong ligament of the knee that originates from the anterolateral surface of the medial condyle of the femur, passes posteriorly and inferiorly between the condyles, and attaches to the posterior intercondylar area of the tibia.Ligaments, Articular: Fibrous cords of CONNECTIVE TISSUE that attach bones to each other and hold together the many types of joints in the body. Articular ligaments are strong, elastic, and allow movement in only specific directions, depending on the individual joint.Pain Measurement: Scales, questionnaires, tests, and other methods used to assess pain severity and duration in patients or experimental animals to aid in diagnosis, therapy, and physiological studies.Gait: Manner or style of walking.Quadriceps Muscle: The quadriceps femoris. A collective name of the four-headed skeletal muscle of the thigh, comprised of the rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis.Pain: An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.Joint DiseasesTreatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Prosthesis Design: The plan and delineation of prostheses in general or a specific prosthesis.Recovery of Function: A partial or complete return to the normal or proper physiologic activity of an organ or part following disease or trauma.Muscle Strength: The amount of force generated by MUSCLE CONTRACTION. Muscle strength can be measured during isometric, isotonic, or isokinetic contraction, either manually or using a device such as a MUSCLE STRENGTH DYNAMOMETER.Joint Deformities, Acquired: Deformities acquired after birth as the result of injury or disease. The joint deformity is often associated with rheumatoid arthritis and leprosy.Prosthesis Failure: Malfunction of implantation shunts, valves, etc., and prosthesis loosening, migration, and breaking.Reoperation: A repeat operation for the same condition in the same patient due to disease progression or recurrence, or as followup to failed previous surgery.Arthrometry, Articular: Measurements of joint flexibility (RANGE OF MOTION, ARTICULAR), usually by employing an angle-measuring device (arthrometer). Arthrometry is used to measure ligamentous laxity and stability. It is often used to evaluate the outcome of ANTERIOR CRUCIATE LIGAMENT replacement surgery.Walking: An activity in which the body advances at a slow to moderate pace by moving the feet in a coordinated fashion. This includes recreational walking, walking for fitness, and competitive race-walking.Osteophyte: Bony outgrowth usually found around joints and often seen in conditions such as ARTHRITIS.Synovitis: Inflammation of a synovial membrane. It is usually painful, particularly on motion, and is characterized by a fluctuating swelling due to effusion within a synovial sac. (Dorland, 27th ed)Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Torque: The rotational force about an axis that is equal to the product of a force times the distance from the axis where the force is applied.Patellofemoral Joint: The articulation between the articular surface of the PATELLA and the patellar surface of the FEMUR.Contracture: Prolonged shortening of the muscle or other soft tissue around a joint, preventing movement of the joint.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Synovial Fluid: The clear, viscous fluid secreted by the SYNOVIAL MEMBRANE. It contains mucin, albumin, fat, and mineral salts and serves to lubricate joints.Hemarthrosis: Bleeding into the joints. It may arise from trauma or spontaneously in patients with hemophilia.Patellar 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.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Ankle Joint: The joint that is formed by the inferior articular and malleolar articular surfaces of the TIBIA; the malleolar articular surface of the FIBULA; and the medial malleolar, lateral malleolar, and superior surfaces of the TALUS.Arthroplasty, Replacement, Hip: Replacement of the hip joint.Prosthesis-Related Infections: Infections resulting from the implantation of prosthetic devices. The infections may be acquired from intraoperative contamination (early) or hematogenously acquired from other sites (late).Movement: The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.Arthrography: Roentgenography of a joint, usually after injection of either positive or negative contrast medium.Popliteal Cyst: A SYNOVIAL CYST located in the back of the knee, in the popliteal space arising from the semimembranous bursa or the knee joint.Anterior Cruciate Ligament Reconstruction: Rebuilding of the ANTERIOR CRUCIATE LIGAMENT to restore functional stability of the knee. AUTOGRAFTING or ALLOGRAFTING of tissues is often used.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Synovial Membrane: The inner membrane of a joint capsule surrounding a freely movable joint. It is loosely attached to the external fibrous capsule and secretes SYNOVIAL FLUID.Hip: The projecting part on each side of the body, formed by the side of the pelvis and the top portion of the femur.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Athletic Injuries: Injuries incurred during participation in competitive or non-competitive sports.Postoperative Complications: Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.ShoesThigh: The portion of the leg in humans and other animals found between the HIP and KNEE.Rotation: Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Rupture: Forcible or traumatic tear or break of an organ or other soft part of the body.Surgery, Computer-Assisted: Surgical procedures conducted with the aid of computers. This is most frequently used in orthopedic and laparoscopic surgery for implant placement and instrument guidance. Image-guided surgery interactively combines prior CT scans or MRI images with real-time video.Orthopedic Procedures: Procedures used to treat and correct deformities, diseases, and injuries to the MUSCULOSKELETAL SYSTEM, its articulations, and associated structures.Femoral Nerve: A nerve originating in the lumbar spinal cord (usually L2 to L4) and traveling through the lumbar plexus to provide motor innervation to extensors of the thigh and sensory innervation to parts of the thigh, lower leg, and foot, and to the hip and knee joints.Tendons: Fibrous bands or cords of CONNECTIVE TISSUE at the ends of SKELETAL MUSCLE FIBERS that serve to attach the MUSCLES to bones and other structures.Osteochondritis Dissecans: A type of osteochondritis in which articular cartilage and associated bone becomes partially or totally detached to form joint loose bodies. Affects mainly the knee, ankle, and elbow joints.Reconstructive Surgical Procedures: Procedures used to reconstruct, restore, or improve defective, damaged, or missing structures.Tourniquets: Devices for the compression of a blood vessel by application around an extremity to control the circulation and prevent the flow of blood to or from the distal area. (From Dorland, 28th ed)Proprioception: Sensory functions that transduce stimuli received by proprioceptive receptors in joints, tendons, muscles, and the INNER EAR into neural impulses to be transmitted to the CENTRAL NERVOUS SYSTEM. Proprioception provides sense of stationary positions and movements of one's body parts, and is important in maintaining KINESTHESIA and POSTURAL BALANCE.Muscle Strength Dynamometer: A device that measures MUSCLE STRENGTH during muscle contraction, such as gripping, pushing, and pulling. It is used to evaluate the health status of muscle in sports medicine or physical therapy.Exercise Therapy: A regimen or plan of physical activities designed and prescribed for specific therapeutic goals. Its purpose is to restore normal musculoskeletal function or to reduce pain caused by diseases or injuries.Braces: Orthopedic appliances used to support, align, or hold parts of the body in correct position. (Dorland, 28th ed)Time Factors: Elements of limited time intervals, contributing to particular results or situations.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Orthotic Devices: Apparatus used to support, align, prevent, or correct deformities or to improve the function of movable parts of the body.Pain, Postoperative: Pain during the period after surgery.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Isometric Contraction: Muscular contractions characterized by increase in tension without change in length.Leg: The inferior part of the lower extremity between the KNEE and the ANKLE.Chondrocalcinosis: Presence of calcium salts, especially calcium pyrophosphate, in the cartilaginous structures of one or more joints. When accompanied by attacks of goutlike symptoms, it is called pseudogout. (Dorland, 27th ed)Disease Progression: The worsening of a disease over time. This concept is most often used for chronic and incurable diseases where the stage of the disease is an important determinant of therapy and prognosis.Soccer: A game in which a round inflated ball is advanced by kicking or propelling with any part of the body except the hands or arms. The object of the game is to place the ball in opposite goals.Posture: The position or attitude of the body.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Arthritis, Infectious: Arthritis caused by BACTERIA; RICKETTSIA; MYCOPLASMA; VIRUSES; FUNGI; or PARASITES.Motion Therapy, Continuous Passive: Movement of a body part initiated and maintained by a mechanical or electrical device to restore normal range of motion to joints, muscles, or tendons after surgery, prosthesis implantation, contracture flexion, or long immobilization.Disability Evaluation: Determination of the degree of a physical, mental, or emotional handicap. The diagnosis is applied to legal qualification for benefits and income under disability insurance and to eligibility for Social Security and workmen's compensation benefits.Stifle: In horses, cattle, and other quadrupeds, the joint between the femur and the tibia, corresponding to the human knee.Hyaluronic Acid: A natural high-viscosity mucopolysaccharide with alternating beta (1-3) glucuronide and beta (1-4) glucosaminidic bonds. It is found in the UMBILICAL CORD, in VITREOUS BODY and in SYNOVIAL FLUID. A high urinary level is found in PROGERIA.Collateral Ligaments: A number of ligaments on either side of, and serving as a radius of movement of, a joint having a hingelike movement. They occur at the elbow, knee, wrist, metacarpo- and metatarsophalangeal, proximal interphalangeal, and distal interphalangeal joints of the hands and feet. (Stedman, 25th ed)Arthroplasty: Surgical reconstruction of a joint to relieve pain or restore motion.Cadaver: A dead body, usually a human body.Arthritis, Rheumatoid: A chronic systemic disease, primarily of the joints, marked by inflammatory changes in the synovial membranes and articular structures, widespread fibrinoid degeneration of the collagen fibers in mesenchymal tissues, and by atrophy and rarefaction of bony structures. Etiology is unknown, but autoimmune mechanisms have been implicated.Bone Marrow DiseasesArthrodesis: The surgical fixation of a joint by a procedure designed to accomplish fusion of the joint surfaces by promoting the proliferation of bone cells. (Dorland, 28th ed)Coxa Vara: Hip deformity in which the femoral neck leans forward resulting in a decrease in the angle between femoral neck and its shaft. It may be congenital often syndromic, acquired, or developmental.Muscle Weakness: A vague complaint of debility, fatigue, or exhaustion attributable to weakness of various muscles. The weakness can be characterized as subacute or chronic, often progressive, and is a manifestation of many muscle and neuromuscular diseases. (From Wyngaarden et al., Cecil Textbook of Medicine, 19th ed, p2251)Polyethylene: A vinyl polymer made from ethylene. It can be branched or linear. Branched or low-density polyethylene is tough and pliable but not to the same degree as linear polyethylene. Linear or high-density polyethylene has a greater hardness and tensile strength. Polyethylene is used in a variety of products, including implants and prostheses.Pain Management: A form of therapy that employs a coordinated and interdisciplinary approach for easing the suffering and improving the quality of life of those experiencing pain.Physical Therapy Modalities: Therapeutic modalities frequently used in PHYSICAL THERAPY SPECIALTY by PHYSICAL THERAPISTS or physiotherapists to promote, maintain, or restore the physical and physiological well-being of an individual.Bone Cements: Adhesives used to fix prosthetic devices to bones and to cement bone to bone in difficult fractures. Synthetic resins are commonly used as cements. A mixture of monocalcium phosphate, monohydrate, alpha-tricalcium phosphate, and calcium carbonate with a sodium phosphate solution is also a useful bone paste.Cartilage Oligomeric Matrix Protein: Major component of chondrocyte EXTRACELLULAR MATRIX of various tissues including bone, tendon, ligament, SYNOVIUM and blood vessels. It binds MATRILIN PROTEINS and is associated with development of cartilage and bone.Activities of Daily Living: The performance of the basic activities of self care, such as dressing, ambulation, or eating.Tibial FracturesViscosupplementation: A therapeutic treatment typically involving INTRA-ARTICULAR INJECTIONS of HYALURONIC ACID and related compounds. The procedure is commonly used in the treatment of OSTEOARTHRITIS with the therapeutic goal to restore the viscoelasticity of SYNOVIAL FLUID, decrease pain, improve mobility and restore the natural protective functions of hyaluronan in the joint.Canes: Sticks used as walking aids. The canes may have three or four prongs at the end of the shaft.Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Lower Extremity: The region of the lower limb in animals, extending from the gluteal region to the FOOT, and including the BUTTOCKS; HIP; and LEG.Osteonecrosis: Death of a bone or part of a bone, either atraumatic or posttraumatic.Viscosupplements: Viscoelastic solutions that are injected into JOINTS in order to alleviate symptoms of joint-related disorders such as OSTEOARTHRITIS.Cartilage: A non-vascular form of connective tissue composed of CHONDROCYTES embedded in a matrix that includes CHONDROITIN SULFATE and various types of FIBRILLAR COLLAGEN. There are three major types: HYALINE CARTILAGE; FIBROCARTILAGE; and ELASTIC CARTILAGE.Hindlimb: Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)Cementation: The joining of objects by means of a cement (e.g., in fracture fixation, such as in hip arthroplasty for joining of the acetabular component to the femoral component). In dentistry, it is used for the process of attaching parts of a tooth or restorative material to a natural tooth or for the attaching of orthodontic bands to teeth by means of an adhesive.Chondrocytes: Polymorphic cells that form cartilage.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Matrilin Proteins: PROTEOGLYCANS-associated proteins that are major components of EXTRACELLULAR MATRIX of various tissues including CARTILAGE; and INTERVERTEBRAL DISC structures. They bind COLLAGEN fibers and contain protein domains that enable oligomer formation and interaction with other extracellular matrix proteins such as CARTILAGE OLIGOMERIC MATRIX PROTEIN.Femoral Fractures: Fractures of the femur.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Prosthesis Fitting: The fitting and adjusting of artificial parts of the body. (From Stedman's, 26th ed)Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Fluoroscopy: Production of an image when x-rays strike a fluorescent screen.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Postural Balance: A POSTURE in which an ideal body mass distribution is achieved. Postural balance provides the body carriage stability and conditions for normal functions in stationary position or in movement, such as sitting, standing, or walking.Longitudinal Studies: Studies in which variables relating to an individual or group of individuals are assessed over a period of time.Arthritis, Experimental: ARTHRITIS that is induced in experimental animals. Immunological methods and infectious agents can be used to develop experimental arthritis models. These methods include injections of stimulators of the immune response, such as an adjuvant (ADJUVANTS, IMMUNOLOGIC) or COLLAGEN.Gait Disorders, Neurologic: Gait abnormalities that are a manifestation of nervous system dysfunction. These conditions may be caused by a wide variety of disorders which affect motor control, sensory feedback, and muscle strength including: CENTRAL NERVOUS SYSTEM DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; NEUROMUSCULAR DISEASES; or MUSCULAR DISEASES.Single-Blind Method: A method in which either the observer(s) or the subject(s) is kept ignorant of the group to which the subjects are assigned.Bandages: Material used for wrapping or binding any part of the body.Artificial Limbs: Prosthetic replacements for arms, legs, and parts thereof.Basketball: A competitive team sport played on a rectangular court having a raised basket at each end.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Osteochondritis: Inflammation of a bone and its overlaying CARTILAGE.Ligaments: Shiny, flexible bands of fibrous tissue connecting together articular extremities of bones. They are pliant, tough, and inextensile.Anti-Inflammatory Agents, Non-Steroidal: Anti-inflammatory agents that are non-steroidal in nature. In addition to anti-inflammatory actions, they have analgesic, antipyretic, and platelet-inhibitory actions.They act by blocking the synthesis of prostaglandins by inhibiting cyclooxygenase, which converts arachidonic acid to cyclic endoperoxides, precursors of prostaglandins. Inhibition of prostaglandin synthesis accounts for their analgesic, antipyretic, and platelet-inhibitory actions; other mechanisms may contribute to their anti-inflammatory effects.Postoperative Care: The period of care beginning when the patient is removed from surgery and aimed at meeting the patient's psychological and physical needs directly after surgery. (From Dictionary of Health Services Management, 2d ed)Hand Joints: The articulations extending from the WRIST distally to the FINGERS. These include the WRIST JOINT; CARPAL JOINTS; METACARPOPHALANGEAL JOINT; and FINGER JOINT.Debridement: The removal of foreign material and devitalized or contaminated tissue from or adjacent to a traumatic or infected lesion until surrounding healthy tissue is exposed. (Dorland, 27th ed)Patellar Dislocation: Displacement of the PATELLA from the femoral groove.Awards and PrizesLeg Bones: The bones of the free part of the lower extremity in humans and of any of the four extremities in animals. It includes the FEMUR; PATELLA; TIBIA; and FIBULA.Postoperative Period: The period following a surgical operation.