Arthroplasty, Replacement, Knee: Replacement of the knee joint.Arthroplasty, Replacement, Hip: Replacement of the hip joint.Knee Joint: A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.Arthroplasty: Surgical reconstruction of a joint to relieve pain or restore motion.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: Partial or total replacement of a joint.Knee Prosthesis: Replacement for a knee joint.Knee: A region of the lower extremity immediately surrounding and including the KNEE JOINT.Prosthesis Failure: Malfunction of implantation shunts, valves, etc., and prosthesis loosening, migration, and breaking.Hip Prosthesis: Replacement for a hip 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.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.Knee Injuries: Injuries to the knee or the knee joint.Prosthesis Design: The plan and delineation of prostheses in general or a specific prosthesis.Joint Prosthesis: Prostheses used to partially or totally replace a human or animal joint. (from UMDNS, 1999)Hip Joint: The joint that is formed by the articulation of the head of FEMUR and the ACETABULUM of the PELVIS.Osteoarthritis, Hip: Noninflammatory degenerative disease of the hip joint which usually appears in late middle or old age. It is characterized by growth or maturational disturbances in the femoral neck and head, as well as acetabular dysplasia. A dominant symptom is pain on weight-bearing or motion.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).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.Treatment 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.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.Recovery of Function: A partial or complete return to the normal or proper physiologic activity of an organ or part following disease or trauma.Arthroplasty, Replacement, Ankle: Replacement of the ANKLE JOINT.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.Patella: The flat, triangular bone situated at the anterior part of the KNEE.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.Joint DiseasesFollow-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.Bone Malalignment: Displacement of bones out of line in relation to joints. It may be congenital or traumatic in origin.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.Femur: The longest and largest bone of the skeleton, it is situated between the hip and the knee.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.Acetabulum: The part of the pelvis that comprises the pelvic socket where the head of FEMUR joins to form HIP JOINT (acetabulofemoral joint).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.Hip Dislocation: Displacement of the femur bone from its normal position at the HIP 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.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.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.Pain, Postoperative: Pain during the period after surgery.Shoulder Joint: The articulation between the head of the HUMERUS and the glenoid cavity of the SCAPULA.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.Arthroplasty, Replacement, Elbow: Replacement of the ELBOW JOINT.Prosthesis Fitting: The fitting and adjusting of artificial parts of the body. (From Stedman's, 26th ed)Femur Head: The hemispheric articular surface at the upper extremity of the thigh bone. (Stedman, 26th ed)Total Disc Replacement: The replacement of intervertebral discs in the spinal column with artificial devices. The procedure is done in the lumbar or cervical spine to relieve severe pain resulting from INTERVERTEBRAL DISC DEGENERATION.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.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.Arthroplasty, Replacement, Finger: Partial or total replacement of one or more FINGERS, or a FINGER JOINT.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.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Knee Dislocation: Slippage of the FEMUR off the TIBIA.Arthralgia: Pain in the joint.Femur Head Necrosis: Aseptic or avascular necrosis of the femoral head. The major types are idiopathic (primary), as a complication of fractures or dislocations, and LEGG-CALVE-PERTHES DISEASE.Polyethylenes: Synthetic thermoplastics that are tough, flexible, inert, and resistant to chemicals and electrical current. They are often used as biocompatible materials for prostheses and implants.Ankylosis: Fixation and immobility of a joint.Arthrodesis: 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)Surgical Procedures, Minimally Invasive: Procedures that avoid use of open, invasive surgery in favor of closed or local surgery. These generally involve use of laparoscopic devices and remote-control manipulation of instruments with indirect observation of the surgical field through an endoscope or similar device.Femoral Neck Fractures: Fractures of the short, constricted portion of the thigh bone between the femur head and the trochanters. It excludes intertrochanteric fractures which are HIP FRACTURES.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.Blood Loss, Surgical: Loss of blood during a surgical procedure.Osteolysis: Dissolution of bone that particularly involves the removal or loss of calcium.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.Bone Transplantation: The grafting of bone from a donor site to a recipient site.Operative Blood Salvage: Recovery of blood lost from surgical procedures for reuse by the same patient in AUTOLOGOUS BLOOD TRANSFUSIONS. It is collected during (intraoperatively) or after completion of (postoperatively) the surgical procedures.Osseointegration: The growth action of bone tissue as it assimilates surgically implanted devices or prostheses to be used as either replacement parts (e.g., hip) or as anchors (e.g., endosseous dental implants).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)Hormone Replacement Therapy: Therapeutic use of hormones to alleviate the effects of hormone deficiency.Osteotomy: The surgical cutting of a bone. (Dorland, 28th ed)Estrogen Replacement Therapy: The use of hormonal agents with estrogen-like activity in postmenopausal or other estrogen-deficient women to alleviate effects of hormone deficiency, such as vasomotor symptoms, DYSPAREUNIA, and progressive development of OSTEOPOROSIS. This may also include the use of progestational agents in combination therapy.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.Surgical Wound Infection: Infection occurring at the site of a surgical incision.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.Hip Injuries: General or unspecified injuries involving the hip.Pain: An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.Leg Length Inequality: A condition in which one of a pair of legs fails to grow as long as the other, which could result from injury or surgery.Hip: The projecting part on each side of the body, formed by the side of the pelvis and the top portion of the femur.Blood Transfusion, Autologous: Reinfusion of blood or blood products derived from the patient's own circulation. (Dorland, 27th ed)Periprosthetic Fractures: Fractures around joint replacement prosthetics or implants. They can occur intraoperatively or postoperatively.Arthroscopy: Endoscopic examination, therapy and surgery of the joint.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.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.Elbow Joint: A hinge joint connecting the FOREARM to the ARM.Equipment Failure Analysis: The evaluation of incidents involving the loss of function of a device. These evaluations are used for a variety of purposes such as to determine the failure rates, the causes of failures, costs of failures, and the reliability and maintainability of devices.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.Postoperative Period: The period following a surgical operation.Gait: Manner or style of walking.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)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.Patient Satisfaction: The degree to which the individual regards the health care service or product or the manner in which it is delivered by the provider as useful, effective, or beneficial.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.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.Menisci, Tibial: The interarticular fibrocartilages of the superior surface of the tibia.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.Femoral Fractures: Fractures of the femur.Osteonecrosis: Death of a bone or part of a bone, either atraumatic or posttraumatic.Chromium Alloys: Specific alloys not less than 85% chromium and nickel or cobalt, with traces of either nickel or cobalt, molybdenum, and other substances. They are used in partial dentures, orthopedic implants, etc.ArthritisRenal Replacement Therapy: Procedures which temporarily or permanently remedy insufficient cleansing of body fluids by the kidneys.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.Ossification, Heterotopic: The development of bony substance in normally soft structures.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)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.Photogrammetry: Making measurements by the use of stereoscopic photographs.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.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.Hemarthrosis: Bleeding into the joints. It may arise from trauma or spontaneously in patients with hemophilia.Metals: Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed)Cadaver: A dead body, usually a human body.Hemiarthroplasty: A partial joint replacement in which only one surface of the joint is replaced with a PROSTHESIS.Coated Materials, Biocompatible: Biocompatible materials usually used in dental and bone implants that enhance biologic fixation, thereby increasing the bond strength between the coated material and bone, and minimize possible biological effects that may result from the implant itself.Device Removal: Removal of an implanted therapeutic or prosthetic device.Postoperative Hemorrhage: Hemorrhage following any surgical procedure. It may be immediate or delayed and is not restricted to the surgical wound.Prostheses and Implants: Artificial substitutes for body parts, and materials inserted into tissue for functional, cosmetic, or therapeutic purposes. Prostheses can be functional, as in the case of artificial arms and legs, or cosmetic, as in the case of an artificial eye. Implants, all surgically inserted or grafted into the body, tend to be used therapeutically. IMPLANTS, EXPERIMENTAL is available for those used experimentally.Preoperative Period: The period before a surgical operation.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.Aluminum Oxide: An oxide of aluminum, occurring in nature as various minerals such as bauxite, corundum, etc. It is used as an adsorbent, desiccating agent, and catalyst, and in the manufacture of dental cements and refractories.Early Ambulation: Procedure to accelerate the ability of a patient to walk or move about by reducing the time to AMBULATION. It is characterized by a shorter period of hospitalization or recumbency than is normally practiced.Awards and PrizesChromium: A trace element that plays a role in glucose metabolism. It has the atomic symbol Cr, atomic number 24, and atomic weight 52. According to the Fourth Annual Report on Carcinogens (NTP85-002,1985), chromium and some of its compounds have been listed as known carcinogens.Orthopedics: A surgical specialty which utilizes medical, surgical, and physical methods to treat and correct deformities, diseases, and injuries to the skeletal system, its articulations, and associated structures.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.Preoperative Care: Care given during the period prior to undergoing surgery when psychological and physical preparations are made according to the special needs of the individual patient. This period spans the time between admission to the hospital to the time the surgery begins. (From Dictionary of Health Services Management, 2d ed)Tranexamic Acid: Antifibrinolytic hemostatic used in severe hemorrhage.Heart Valve Prosthesis Implantation: Surgical insertion of synthetic material to repair injured or diseased heart valves.Patellofemoral Joint: The articulation between the articular surface of the PATELLA and the patellar surface of the FEMUR.Orthopedic Procedures: Procedures used to treat and correct deformities, diseases, and injuries to the MUSCULOSKELETAL SYSTEM, its articulations, and associated structures.Outcome Assessment (Health Care): Research aimed at assessing the quality and effectiveness of health care as measured by the attainment of a specified end result or outcome. Measures include parameters such as improved health, lowered morbidity or mortality, and improvement of abnormal states (such as elevated blood pressure).Ceramics: Products made by baking or firing nonmetallic minerals (clay and similar materials). In making dental restorations or parts of restorations the material is fused porcelain. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Boucher's Clinical Dental Terminology, 4th ed)Heart Valve Prosthesis: A device that substitutes for a heart valve. It may be composed of biological material (BIOPROSTHESIS) and/or synthetic material.Registries: The systems and processes involved in the establishment, support, management, and operation of registers, e.g., disease registers.Length of Stay: The period of confinement of a patient to a hospital or other health facility.Arthritis, Infectious: Arthritis caused by BACTERIA; RICKETTSIA; MYCOPLASMA; VIRUSES; FUNGI; or PARASITES.Humeral Head: The portion of the upper rounded extremity fitting into the glenoid cavity of the SCAPULA. (from Stedman, 27th ed)Hallux Rigidus: A condition caused by degenerative arthritis (see OSTEOARTHRITIS) of the METATARSOPHALANGEAL JOINT of the great toe and characterized by pain and limited dorsiflexion, but relatively unrestricted plantar flexion.Arthrography: Roentgenography of a joint, usually after injection of either positive or negative contrast medium.Activities of Daily Living: The performance of the basic activities of self care, such as dressing, ambulation, or eating.Contracture: Prolonged shortening of the muscle or other soft tissue around a joint, preventing movement of the joint.Blood Transfusion: The introduction of whole blood or blood component directly into the blood stream. (Dorland, 27th ed)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.Tantalum: Tantalum. A rare metallic element, atomic number 73, atomic weight 180.948, symbol Ta. It is a noncorrosive and malleable metal that has been used for plates or disks to replace cranial defects, for wire sutures, and for making prosthetic devices. (Dorland, 28th ed)Nerve Block: Interruption of NEURAL CONDUCTION in peripheral nerves or nerve trunks by the injection of a local anesthetic agent (e.g., LIDOCAINE; PHENOL; BOTULINUM TOXINS) to manage or treat pain.Rotator Cuff: The musculotendinous sheath formed by the supraspinatus, infraspinatus, subscapularis, and teres minor muscles. These help stabilize the head of the HUMERUS in the glenoid fossa and allow for rotation of the SHOULDER JOINT about its longitudinal axis.DislocationsTitanium: A dark-gray, metallic element of widespread distribution but occurring in small amounts; atomic number, 22; atomic weight, 47.90; symbol, Ti; specific gravity, 4.5; used for fixation of fractures. (Dorland, 28th ed)Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)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.Joint Capsule: The sac enclosing a joint. It is composed of an outer fibrous articular capsule and an inner SYNOVIAL MEMBRANE.Humerus: Bone in humans and primates extending from the SHOULDER JOINT to the ELBOW JOINT.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.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Intraoperative Care: Patient care procedures performed during the operation that are ancillary to the actual surgery. It includes monitoring, fluid therapy, medication, transfusion, anesthesia, radiography, and laboratory tests.Metatarsophalangeal Joint: The articulation between a metatarsal bone (METATARSAL BONES) and a phalanx.Aortic Valve: The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle.Durapatite: The mineral component of bones and teeth; it has been used therapeutically as a prosthetic aid and in the prevention and treatment of osteoporosis.Scapula: Also called the shoulder blade, it is a flat triangular bone, a pair of which form the back part of the shoulder girdle.Cobalt: A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.Prosthesis Implantation: Surgical insertion of a prosthesis.Hospitals, Low-Volume: Hospitals with a much lower than average utilization by physicians and smaller number of procedures.Enzyme Replacement Therapy: Therapeutic replacement or supplementation of defective or missing enzymes to alleviate the effects of enzyme deficiency (e.g., GLUCOSYLCERAMIDASE replacement for GAUCHER DISEASE).Venous Thrombosis: The formation or presence of a blood clot (THROMBUS) within a vein.Intraoperative Complications: Complications that affect patients during surgery. They may or may not be associated with the disease for which the surgery is done, or within the same surgical procedure.Tuberculosis, Osteoarticular: Tuberculosis of the bones or joints.Therapeutic Irrigation: The washing of a body cavity or surface by flowing water or solution for therapy or diagnosis.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.Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Hemostasis, Surgical: Control of bleeding during or after surgery.Quality of Life: A generic concept reflecting concern with the modification and enhancement of life attributes, e.g., physical, political, moral and social environment; the overall condition of a human life.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.Replantation: Restoration of an organ or other structure to its original site.Intraoperative Period: The period during a surgical operation.Antibiotic Prophylaxis: Use of antibiotics before, during, or after a diagnostic, therapeutic, or surgical procedure to prevent infectious complications.Chi-Square Distribution: A distribution in which a variable is distributed like the sum of the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another.Rupture: Forcible or traumatic tear or break of an organ or other soft part of the body.Fracture Fixation, Internal: The use of internal devices (metal plates, nails, rods, etc.) to hold the position of a fracture in proper alignment.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)Metal-on-Metal Joint Prostheses: Types of prosthetic joints in which both wear surfaces of the joint coupling are metallic.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.Cervical Vertebrae: The first seven VERTEBRAE of the SPINAL COLUMN, which correspond to the VERTEBRAE of the NECK.Intervertebral Disc Degeneration: Degenerative changes in the INTERVERTEBRAL DISC due to aging or structural damage, especially to the vertebral end-plates.Patient Selection: Criteria and standards used for the determination of the appropriateness of the inclusion of patients with specific conditions in proposed treatment plans and the criteria used for the inclusion of subjects in various clinical trials and other research protocols.Osteophyte: Bony outgrowth usually found around joints and often seen in conditions such as ARTHRITIS.Bone Nails: Rods of bone, metal, or other material used for fixation of the fragments or ends of fractured bones.Injections, Intra-Articular: Methods of delivering drugs into a joint space.Hospitals, High-Volume: Hospitals with a much higher than average utilization by physicians and a large number of procedures.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.Antifibrinolytic Agents: Agents that prevent fibrinolysis or lysis of a blood clot or thrombus. Several endogenous antiplasmins are known. The drugs are used to control massive hemorrhage and in other coagulation disorders.Sex Factors: Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.Anesthesia, Conduction: Injection of an anesthetic into the nerves to inhibit nerve transmission in a specific part of the body.Intervertebral Disc: Any of the 23 plates of fibrocartilage found between the bodies of adjacent VERTEBRAE.Reconstructive Surgical Procedures: Procedures used to reconstruct, restore, or improve defective, damaged, or missing structures.Hip Fractures: Fractures of the FEMUR HEAD; the FEMUR NECK; (FEMORAL NECK FRACTURES); the trochanters; or the inter- or subtrochanteric region. Excludes fractures of the acetabulum and fractures of the femoral shaft below the subtrochanteric region (FEMORAL FRACTURES).Thromboembolism: Obstruction of a blood vessel (embolism) by a blood clot (THROMBUS) in the blood stream.Lumbosacral Plexus: The lumbar and sacral plexuses taken together. The fibers of the lumbosacral plexus originate in the lumbar and upper sacral spinal cord (L1 to S3) and innervate the lower extremities.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.Surgical Procedures, Elective: Surgery which could be postponed or not done at all without danger to the patient. Elective surgery includes procedures to correct non-life-threatening medical problems as well as to alleviate conditions causing psychological stress or other potential risk to patients, e.g., cosmetic or contraceptive surgery.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.Synovial Fluid: The clear, viscous fluid secreted by the SYNOVIAL MEMBRANE. It contains mucin, albumin, fat, and mineral salts and serves to lubricate joints.Foreign-Body Migration: Migration of a foreign body from its original location to some other location in the body.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.Analgesia: Methods of PAIN relief that may be used with or in place of ANALGESICS.Pelvic Bones: Bones that constitute each half of the pelvic girdle in VERTEBRATES, formed by fusion of the ILIUM; ISCHIUM; and PUBIC BONE.