Acetabular component The portion of a total hip replacement prosthesis that is inserted into the acetabulum – the socket part of  a ball and socket joint.


Acetabular cup See Acetabular component.

Acetabular prosthesis See Acetabular component.

Antibiotic-loaded bone cement See cement.

Arthrodesis A procedure where the bones of a natural joint are fused together (stiffened).

Arthroplasty A procedure where a natural joint is reconstructed with an artificial prosthesis.

ABHI Association of British Healthcare Industries -the UK trade association of medical device suppliers.

ASA American Society of Anaesthesiologists scoring system for grading the overall physical condition of the patient, as follows: P1 – fit and healthy; P2 – mild disease, not incapacitating; P3 – incapacitating systemic disease; P4 –life threatening disease; P5 – expected to die within 24 hrs without an operation.

abdominal bracing – a technique of tensing the stomach muscles to support the spine.

acromion – the roof, or highest point, of the shoulder that is formed by a part of the scapula, or shoulder blade.

adhesions – abnormal bands of tissue that grow between joint surfaces, restricting motion.

allodynia – pain due to a stimulus that does not normally provoke pain.

analgesia – absence of pain in response to stimulation that would normally be painful.

antibody – a special protein produced by the body’s immune system that recognizes and helps fight infectious agents and other foreign substances that invade the body.

artery – any tubular, branching vessel that carries blood from the heart throughout the body.

arthralgia – pain in a joint, usually due to arthritis or arthropathy.

arthritis – inflammation of the joint.

arthrogram – x-ray of a joint.

arthroscopy – the use of an intra-articular camera inserted into the joint through a small incision to show the inside of a joint; the procedure allows the physician to also assess, repair, or reconstruct various tissues both within and around joints.

atrophy – wasting away of a body part or tissue

Bearing type The two surfaces that articulate together in a joint replacement. Options include metal-on-polyethylene, metal-on-metal, ceramic-on-polyethylene, ceramic-on-metal and ceramic-onceramic.

Bilateral operation Operation performed on both sides, e.g. left and right knee procedures, carried out during a single operation.

BMI Body mass index. A statistical tool used to estimate a healthy body weight based on an individual’s height. The BMI is calculated by dividing a person’s weight (kg) by the square of their height (m2).

BOA British Orthopaedic Association -the professional body representing orthopaedic surgeons.

Bone cement See cement.


Brand (of prosthesis)  The brand of a prosthesis (or implant) is the manufacturer’s product name, e.g. the Exeter V40 brand for hips, the PFC Sigma brand for knees, the Mobility brand for ankles, the Delta Xtend brand for shoulders and the Coonrad Morrey for elbows.

benign – noncancerous; a mild disease or condition.

bone – living tissue that makes up the body’s skeleton.

bone graft – a surgical procedure in which healthy bone is transplanted from another part of the patient’s body into the affected area.

bone scan – a nuclear imaging method to evaluate any degenerative and/or arthritic changes in the joints; to detect bone diseases and tumors; to determine the cause of bone pain or inflammation.

bursas – fluid-filled sacs between bones and ligaments, or other adjacent structures.

bursitis – inflammation of the bursas.

CQC Care Quality Commission. Regulators of care provided by the NHS, local authorities, private companies and voluntary organisations.

Case ascertainment Proportion of all relevant joint replacement procedures performed in England and Wales that are entered into the NJR.

Case mix Term used to describe variation in surgical practice, relating to factors such as indications for surgery, patient age and gender.

Cement  The material used to fix cemented joint replacements to bone – polymethyl methacrylate (PMMA). Antibiotic can be added to bone cement to try and reduce the risk of infection.


Cemented Prostheses designed to be fixed into the bone using cement.

Cementless Prostheses designed to be fixed into the bone by bony ingrowth or ongrowth, without using cement.

Compliance The percentage of all total joint procedures that have been entered into the NJR within any given period compared with the expected number of procedures performed. The expected number of can be the number of levies returned, or for the NHS Sector only, the number of procedures submitted to HES and PEDW.

Competing risks survival analysis An alternative to standard survival analysis methods (such as Kaplan-Meier estimation or the Cox proportional hazards model) when there are competing risks. A competing risk can prevent the event of interest from occurring (in this case, death is a competing risk to the risk of revision as patients who die will never experience revision). A competing-risks survival analysis adjusts the results accordingly.

Confidence interval (CI) A confidence interval (CI) gives an estimated range of values which is likely to include the unknown population parameter (e.g. a revision rate) being estimated from the given sample. If independent samples are taken repeatedly from the same population, and a confidence interval calculated for each sample, then a certain percentage (confidence level: e.g. 95%) of the intervals will include the unknown population parameter.

Confounding Systematic variation due to the presence of factors not on the causal pathway, which affect the outcome, which are unequally distributed amongst interventions being compared which leads to inaccurate inferences about the results

Cox proportional hazards model A semi-parametric survival analysis model commonly used to model time-to-event data as it does not require the underlying hazard function to take a particular shape. As it is a multi-variable model, it can be used to explore the effects of covariates on the outcome of interest and reduce the impact of confounding.

Cross-linked polyethylene See modified polyethylene.

Cumulative hazard An ‘accumulated’ hazard rate over time; the hazard rate at a particular point in time is the rate of occurrence of the event (revision or death) amongst those in whom the event has not yet occurred. Estimated using the Nelson-Aalen estimate.

Cup See Acetabular component.

cancellous tissue – the sponge-like tissue inside bones.

cartilage – a connective tissue that covers the ends of bones in a joint.

cast – a cast holds a broken bone in place as it heals, prevents or decreases muscle contractures, or provides immobilization, especially after surgery. Casts immobilize the joint above and the joint below the area that is to be kept straight and without motion. For example, a child with a forearm fracture will have a long arm cast to immobilize the wrist and elbow joints.

chondroblasts – immature cartilage-producing cells.

clubfoot (Also called talipes equinovarus.) – a foot deformity that is detected at birth. It affects the bones, muscles, tendons, and blood vessels and can affect one or both feet. The foot is usually short and broad in appearance and the heel points downward while the front half of the foot, or forefoot, turns inward. The heel cord (Achilles tendon) is tight. The heel can appear narrow and the muscles in the calf are smaller compared to a normal lower leg.

compact tissue – the harder, outer tissue of bones.

computed tomography scan (Also called CT or CAT scan.) – a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.

congenital – present at birth.

contusion – a bruise caused by a blow to the muscle, tendon, or ligament; caused when blood pools around the injury and discolors the skin.

corticosteroids (Also called glucocorticoids.) – potent anti-inflammatory hormones that are made naturally in the body or synthetically for use as drugs; most commonly prescribed drug of this type is prednisone.


Data collection periods for annual report analysis  The NJR Annual Report Part One reports on data collected between 1 April 2012 and 31 March 2013 – the 2012/13 financial year. The NJR Annual Report Parts Two and Four analyse data on hip, knee, ankle, elbow, and shoulder procedures undertaken between 1 January and 31 December 2012 inclusive – the 2012 calendar year. The NJR Annual Report Part Three reports on hip, knee and ankle joint replacement revision rates for procedures that took place between 1 April 2003 and 31 December 2012.

DDH Developmental dysplasia of the hip. A condition where the hip joint is malformed, usually with a shallow socket (acetabulum), which may cause instability.

DH Department of Health.

DVT Deep vein thrombosis. A blood clot that can form in the veins of the leg, and is recognised as a significant risk after joint replacement surgery.

developmental dysplasia of the hip (DDH) – a condition of the hip joint that is congenital (present at birth). The hip joint is created as a ball-and-socket joint. In DDH, the hip socket may be shallow, letting the “ball” of the long leg bone, also known as the femoral head, slip in and out of the socket. The “ball” may move partially or completely out of the hip socket.

dislocation – a dislocation occurs when extreme force is put on a ligament causing the two bone ends to separate. Dislocations can also affect a joint, the point where two or more bones come together. The joint is created as a “ball-and-socket” joint. A dislocated joint causes the head of the bone (ball) to partially or completely come out of the socket.


Excision arthroplasty A procedure where the articular ends of the bones are simply excised, so that a gap is created between them, or when a joint replacement is removed and not replaced by another prosthesis.

electromyogram (EMG) – a test that measures the electrical activity of a muscle or a group of muscles. An EMG can detect abnormal electrical muscle activity due to diseases and neuromuscular conditions.

erythrocyte sedimentation rate (Also called ESR or sed rate.) – a measurement of how quickly red blood cells fall to the bottom of a test tube. When swelling and inflammation are present, the blood’s proteins clump together and become heavier than normal. Thus, when measured, they fall and settle faster at the bottom of the test tube. Generally, the faster the blood cells fall, the more severe the inflammation.


Femoral component (hip) Part of a total hip joint that is inserted into the femur (thigh bone) of the patient. It normally consists of a stem and head (ball).

Femoral component (knee) Portion of a knee prosthesis that is used to replace the articulating surface of the femur (thigh bone).

Femoral head Spherical portion of the femoral component of the artificial hip replacement.

Femoral prosthesis Portion of a total joint replacement used to replace damaged parts of the femur (thigh bone).

Femoral stem The part of a modular femoral component inserted into the femur (thigh bone). Has a femoral head mounted on it to form the complete femoral component.

Flexible parametric proportional hazards model Developed by Royston and Parmar, this model extends the standard Cox proportional hazards approach by modelling the baseline distribution parametrically using a restricted cubic spline function. This allows more flexibility in modelling the shape of the baseline hazard function than using standard parametric distributions.

Funnel plot A graph of a performance measure for each unit plotted against the unit’s number of cases. Control limits are shown to indicate acceptable performance.

femur – thighbone.

fractures – a partial or complete break in the bone.


Glenoid component The portion of a total shoulder replacement prosthesis that is inserted into the scapula – the socket part of a ball and socket joint in conventional shoulder replacement or the ball part in reverse shoulder replacement.



Glenoid head Domed head portion of the glenoid component of the reverse shoulder replacement attached to the scapula.


Head See Femoral head and/or Humeral head.

Healthcare provider NHS or independent sector organisation that provides healthcare; in the case of the NJR, orthopaedic hip, knee, ankle, elbow or shoulder replacement surgery.

HES Hospital Episode Statistics. Data on case mix, procedures, length of stay and other hospital statistics collected routinely by NHS hospitals in England.

HQIP Healthcare Quality Improvement Partnership. Manages the NJR on behalf of the Department of Health. Promotes quality in health and social care services and works to increase the impact that clinical audit has nationally.

Humeral component (elbow) Part of a total elbow joint that is inserted into the humerus (upper arm bone) of the patient to replace the articulating surface of the humerus.

Humeral component (shoulder) Part of a total or partial shoulder joint that is inserted into the humerus (upper arm bone) of the patient. It normally consists of a humeral stem and head (ball) in conventional shoulder replacement or a humeral stem and a humeral cup in a reverse shoulder replacement.

Humeral cup The shallow socket of a reverse shoulder replacement attached to the scapula.

Humeral head Domed head portion of the humeral component of the artificial shoulder replacement attached to the humeral stem.

Humeral prosthesis Portion of a total joint replacement used to replace damaged parts of the humerus (upper arm bone).

Humeral stem The part of a modular humeral component inserted into the humerus (upper arm bone). Has a humeral head or humeral cup mounted on it to form the complete humeral component.

Hybrid procedure Joint replacement procedure in which cement is used to fix one prosthetic component while the other is cementless. For hip procedures, the term hybrid covers both reverse hybrid (cementless stem, cemented socket) and hybrid (cemented stem, cementless socket).

hip – the region on each side of the pelvis; made up of three sections: ilium, ischium, and pubis; the upper part of the femur (upper leg bone) fits into the hip via a ball-and-socket joint; the socket is a cup-shaped bone of the pelvis, called the acetabulum, and the ball is the head of the femur.


Image/computer-guided surgery Surgery performed by the surgeon, using real-time images and data computed from these to assist alignment and positioning of prosthetic components.

Independent hospital A hospital managed by a commercial company that predominantly treats privately-funded patients but does also treat NHS-funded patients.

Index joint The primary joint replacement that is the subject of an NJR entry.

Indication (for surgery) The reason for surgery. The NJR system allows for more than one indication to be recorded.

ISTC Independent sector treatment centre (see Treatment centre).

immune system – complex network of specialized cells and organs that work together to defend the body against attacks by “foreign” invaders such as bacteria and viruses; in some rheumatic conditions, it appears that the immune system does not function properly and may even work against the body.

incidence – statistic that equals the number of new cases of a particular disease that occur in a population during a defined period of time, usually one year.

infectious arthritis – an infection in the joint fluid and tissues.


joint – where the ends of two or more bones meet.

juvenile rheumatoid arthritis (JRA) – a form of arthritis in children ages 16 or younger that causes inflammation and stiffness of the joints.


Kaplan-Meier Estimates of the cumulative probability of failure (revision or death) that properly take into account ‘censored’ data. Censorings arise from incomplete follow up; for revision, for example, a patient may have died or reached the end the analysis period (end of 2012) without having been revised. The estimates do not adjust for any confounding factors.

kyphosis – a forward curvature of the back bones (vertebrae) in the upper back area, giving a “humpback” appearance.


Lateral resurfacing (elbow) Partial resurfacing of the elbow with a humeral surface replacement component used with a lateral resurfacing head inserted with or without cement.

Levy Additional payment placed on the sales of specific hip, knee, ankle, elbow, and shoulder implants to cover the costs associated with the ongoing operation and development of the NJR.

Linkable percentage Linkable percentage is the percentage of all relevant procedures that have been entered into the NJR, which may be linked via NHS number to other procedures performed on the same patient.

Linkable procedures Procedures entered into the NJR database that are linkable to a patient’s previous or subsequent procedures by the patient’s NHS number.

Linked total elbow Where the humeral and ulnar parts of a total elbow replacement are physically connected.



LHMoM Large head metal-on-metal. Where a metal femoral head of 36mm diameter or greater is used in conjunction with a femoral stem, and is articulating with either a metal resurfacing cup or a metal liner in a modular acetabular cup. Resurfacing hip replacements are excluded from this group.


LMWH Low molecular weight Heparin. A blood-thinning drug used in the prevention and treatment of deep vein thrombosis (DVT)

Legg-Calvé-Perthes disease – A temporary condition in children in which the head, or “ball,” of the thigh bone, referred to as the femoral head, loses its blood supply. As a result, the “ball” of the thigh bone collapses. The body will absorb the dead tissue and replace the dead bone cells with new bone cells. The new bone cells will eventually reshape the “ball” of the thigh bone. This condition causes the hip joint to become painful and stiff for a period of time.

ligaments – a white, shiny, flexible band of fibrous tissue that binds joints together and connects various bones and cartilage.

lordosis – a curvature of the back bones (vertebrae) in the lower back area, giving the child a “swayback” appearance.


MDS Minimum dataset, the set of data fields collected by the NJR. Some of the data fields are mandatory (i.e. they must be filled in). Fields that relate to patients’ personal details must only be completed where informed patient consent has been obtained.

MDS 1 (MDSv1) Minimum dataset version one, used to collect data from 1 April 2003. MDS 1 closed to new data entry on 1 April 2005.

MDS 2 (MDSv2) Minimum dataset version two, introduced on 1 April 2004. MDS 2 replaced MDS 1 as the official data set on 1 June 2004.

MDS 3 (MDSv3) Minimum dataset version three, introduced on 1 November 2007 replacing MDS 2 as the new official data set.

MDS 4 (MDSv4) Minimum dataset version four, introduced on 1 April 2010 replacing MDS 3 as the new official dataset. This dataset has the same hip and knee MDS 3 dataset but includes the data collection for total ankle replacement procedures.

MDS 5 (MDSv5) Minimum dataset version five, introduced on 1 April 2012 replacing MDS 4 as the new official dataset. This dataset has the same hip, knee and ankle MDS 4 dataset but includes the data collection for total elbow and total shoulder replacement procedures.

MHRA Medicines and Healthcare products Regulatory Agency – the UK regulatory body for medical devices.

MIS Minimally-invasive surgery Surgery performed using small incisions (usually less than 10 cm). This may require the use of special instruments.

Mixing and matching Also known as ‘cross breeding’. Hip replacement procedure in which a surgeon chooses to implant a femoral component from one manufacturer with an acetabular component from another.

Modified Polyethylene Any component made of polyethylene which has been modified in some way in order to improve its performance characteristics. Some of these processes involve chemical changes, such as increasing the cross-linking of the polymer chains or the addition of vitamin E and/or other antioxidants . Others are physical processes such as heat pressing or irradiation in a vacuum or inert gas.

Modular Component composed of more than one piece, e.g. a modular acetabular cup shell component with a modular cup liner, or femoral stem coupled with a femoral head.

Monobloc Component composed of, or supplied as, one piece, e.g. a monobloc knee tibial component

magnetic resonance imaging (MRI) – a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

metatarsus adductus (Also called metatarsus varus.) – a common, congenital (present at birth) foot deformity that causes the front half of the foot, or forefoot, to turn inward.

muscular dystrophy (MD) – is a broad term that describes a genetic (inherited) disorder of the muscles. MD causes the muscles in the body to become very weak. The muscles break down and are replaced with fatty deposits over time. The most common form of MD is called Duchenne muscular dystrophy (DMD).

musculoskeletal system – the complex system that include: bones, joints, ligaments, tendons, muscles, and nerves.


Nelson-Aalen estimator An estimate of the cumulative hazard rate.

NHS National Health Service.

NICE National Institute for Health and Care Excellence.

NICE benchmark See ODEP ratings.

NJR National Joint Registry for England, Wales and Northern Ireland. The NJR has collected and analysed data on hip and knee replacements since 1 April 2003, on ankle replacements since 1 April 2010 and on elbow replacements and shoulder replacements since April 2012. It covers both the NHS and independent healthcare sectors to ensure complete recording of national activity in England, Wales and Northern Ireland.

NJR Centre National coordinating centre for the NJR.

NJR Stats Online Web facility for viewing and downloading NJR statistics on

neuralgia – pain in distribution of nerve or nerves.

neuritis – inflammation of a nerve or nerves.

nodule – bump.

NSAID – abbreviation for nonsteroidal anti-inflammatory drug, which do not contain corticosteroids and are used to reduce pain and inflammation; aspirin and ibuprofen are two types of NSAIDs.

nursemaid’s elbow – a condition common in children younger than 4 years of age in which the radius (one of the bones of the forearm) slips out of place from its attachment to the elbow joint.


ODEP Orthopaedic Data Evaluation Panel of the NHS Supply Chain.

ODEP ratings ODEP ratings are the criteria for product categorisation of prostheses for primary total hip replacement against benchmarks. The letter represents the strength of evidence and the number the length of time in years during which the implant has been studied. The full benchmark is 10A and the entry is at 3 years with progression through 5 and 7 years. Pre-entry submissions are also recorded. “A” represents strong supporting evidence for the use of the prosthesis, “B” less strong but acceptable evidence. All implants that are used without a 10-year benchmark should be followed up closely.


OPCS-4 Office of Population, Censuses and Surveys: Classification of Surgical Operations and Procedures, 4th Revision – a list of surgical procedures and codes

Outlier Data for a surgeon, unit or implant brand that falls outside of the defined control limits.

occult – disease or symptoms that are not readily detectable by physical examination or laboratory tests.

orthopaedic surgeon (Also called an orthopaedist.) – a physician who diagnoses, treats, manages the rehabilitation process, and provides prevention protocols for patients who suffer from injury or disease in any of the components of the musculoskeletal system.

orthopaedic surgery (Also called orthopaedics.) – the medical specialty devoted to the diagnosis, treatment, rehabilitation, and prevention of injuries and diseases of the body’s musculoskeletal system.

Osgood-Schlatter disease – An overuse condition or injury of the knee that causes pain and swelling below the knee area.

osteitis pubis – an inflammation of the pubic symphysis, the bone to which the two hip bones connect in front of the body.

osteoblast – cell found in bone; its function is to form the tissue and minerals that give bone its strength.

osteocyte – cell found within the bone; its function is to help maintain bone as living tissue.

osteogenesis imperfecta (Also called OI or brittle-bone disease.) – a genetic (inherited) disorder characterized by bones that break easily. There may not be a particular cause for the broken bones.

osteomyelitis – an infection in the bone.

overuse conditions – injuries due to minor trauma involving soft tissue injuries -injuries that affect the bone, muscles, ligaments, and/or tendons.


Pantalar (ankle) Affecting the whole talus, i.e. the ankle (tibio talar) joint, the subtalar (talo calcaneal) joint and the talonavicular joint.

triple arthrodesis

Patella resurfacing Replacement of the surface of the patella (knee cap) with a prosthesis

Patello-femoral knee Procedure involving replacement of the trochlear and replacement resurfacing of the patella.


Patello-femoral prosthesis Two-piece knee prosthesis that provides a prosthetic (knee) articulation surface between the patella and trochlear.

Patient consent Patient personal details may only be submitted to the NJR where explicit informed patient consent has been given or where patient consent has not been recorded. If a patient declines to give consent, only the anonymous operation and implant data may be submitted.

Patient physical status See ASA.

Patient procedure Type of procedure carried out on a patient, e.g. primary total prosthetic replacement using cement.

Patient-time The summation of time (in years) for a cohort of primary procedures where the time is measured from the primary date to either date of revision, date of patient’s death or analysis date (last observation date).

PDS The NHS Personal Demographics Service is the national electronic database of NHS patient demographic details. The NJR uses the PDS Demographic Batch Service (DBS) to source missing NHS numbers and to determine when patients recorded on the NJR have died.

PEDW Patient Episode Database for Wales. The Welsh equivalent to Hospital Episode Statistics (HES) in England.

Poisson distribution This distribution expresses the probability of a number of relatively rare events occurring in a fixed time if these events occur with a known average rate and are independent of the time since the last event. It is a special case of the binomial distribution in that it models discrete events.

Primary hip/knee/ankle/elbow/shoulder replacement The first time a total joint replacement operation is performed on any individual joint in a patient.

Prosthesis Orthopaedic implant used in joint replacement procedures, e.g. a total hip, a unicondylar knee, a total ankle, a reverse shoulder or a radial head replacement.

PROMs Patient Reported Outcome Measures.

PTIR Patient-Time Incidence Rate. This is the rate of occurrences of an event (i.e. revision) for a given total time at risk.

pain – an unpleasant sensory or emotional experience primarily associated with tissue damage, or described in terms of tissue damage, or both.

pain threshold – the least experience of pain that a person can recognize.

pain tolerance level – the greatest level of pain that a person is prepared to tolerate.

patella – the knee-cap.

pauciarticular – a form of juvenile rheumatoid arthritis that affects four or less joints.

pelvis – a basin-shaped structure that supports the spinal column containing the sacrum, coccyx, and hip bones (ilium, pubis, and ischium).

periosteum – the compact and cancellous tissues of bone together; beneath the hard outer shell of the periosteum, there are tunnels and canals through which blood and lymphatic vessels run to carry nourishment for the bone; muscles, ligaments, and tendons may attach to the periosteum.

polyarticular – a form of juvenile rheumatoid arthritis that affects five or more joints.

polymyalgia rheumatica – condition of unknown cause that affects the lining of joints, particularly in the shoulders and hips.

predisposition – tendency to develop a certain disease.

prevalence – statistic that equals the total number of people in a population with a certain disease at a given time.

psoriatic arthritis – a form of arthritis associated with psoriasis, a skin and nail disease.


Radial head component (elbow) Part of a partial elbow joint that is inserted into the radius (outer lower arm bone) of the patient to replace the articulating surface of the radial head. May be monobloc or modular.

Resurfacing (hip) Resurfacing of the femoral head with a surface replacement femoral prosthesis and insertion of a monobloc acetabular cup, with or without cement.

Resurfacing (shoulder) Resurfacing of the humeral head with a surface replacement humeral prosthesis inserted, with or without cement.

Reverse shoulder replacement Replacement of the shoulder joint where a glenoid head is attached to the scapula and the humeral cup to the humerus.

Revision burden The proportion of revision procedures carried out as a percentage of the total number of surgeries on that particular joint.

Revision hip/knee/ankle/elbow/shoulder replacement Operation performed to remove (and usually replace) one or more components of a total joint prosthesis for whatever reason.

R.I.C.E. – rest, ice, compression, and elevation.

range of motion – measurement of the extent to which a joint can go through all its normal spectrum of movements.

reactive arthritis (Also called Reiter’s syndrome.) – a type of arthritis that occurs as a reaction to an infection.

rheumatoid factor – special kind of antibody often found in people with rheumatoid arthritis.

rheumatologist – a physician who specializes in the treatment of arthritis and other rheumatic diseases that may affect joints, muscles, bones, skin, and other tissues.

rotator cuff – consists of muscles and tendons that hold the shoulder in place.


Shoulder hemiarthroplasty Replacement of the humeral head with a humeral stem and head or shoulder resurfacing component which articulates with the natural glenoid

Single-stage revision A revision carried out in a single operation.

Subtalar joint (ankle) The joint between the talus and the calcaneum.

Surgical approach Method used by a surgeon to gain access to, and expose, the joint.

Survivorship analysis A statistical method that is used to determine what fraction of a population, such as those who have had a particular hip implant, has survived unrevised past a certain time. See Kaplan-Meier.

scapula – shoulder blade.

sciatica (Also called lumbar radiculopathy.) – a pain that originates along the sciatic nerve.

scoliosis – a lateral, or sideways curvature and rotation of the back bones (vertebrae), giving the appearance that the person is leaning to one side.

sepsis – the presence of bacteria, virus, fungus, or other organism in the blood or other tissues and the toxins associated with the invasion.

septic (infectious) arthritis – an infection in the joint fluid and tissues.

slipped capital femoral epiphysis (SCFE) – a condition in children in which the head, or “ball,” of the thigh bone, referred to as the femoral head, slips off the neck of the thigh bone. An analogy commonly used to describe this condition is that is can be like a scoop of ice cream slipping off the top of a cone. This condition causes the hip joint to become painful and stiff.

soft tissue – the ligaments, tendons, and muscles in the musculoskeletal system.

somatosensory – refers to sensory signals from all tissues of the body including skin, viscera, muscles, and joints.

spine – a column in the body consisting of 33 vertebrae.

spondylosis – a degenerative process of the cervical spine that causes narrowing of the spinal canal and neural foramina, and produces compression of the spinal cord and nerve roots.

sprain – a partial or complete tear of a ligament.

strain – a partial or complete tear of a muscle or tendon.

stress fracture – a bone injury caused by overuse.

subchondral tissue – the smooth tissue at the ends of bones, which is covered with another type of tissue called cartilage.

synovial fluid – a clear, sticky fluid that is released by the synovial membrane and acts as a lubricant for joints and tendons.

synovial membrane – a tissue that lines and seals the joint.

synovitis – inflammation of the synovial membrane, the tissue that lines and protects the joint.

synovium – a fibrous envelope that produces a fluid to help to reduce friction and wear in a joint.

systemic – disease or symptoms that affect many different parts of the body.

systemic juvenile rheumatoid arthritis – a form of juvenile rheumatoid arthritis that affects joints and sometimes internal organs.


Talar component Portion of an ankle prosthesis that is used to replace the articulating surface of the talus at the ankle joint

TAR Total ankle replacement (total ankle arthroplasty). Replacement of both tibial and talar surfaces, with or without cement.

TED stockings Thrombo embolus deterrent (TED) stockings. Elasticised stockings that can be worn by patients following surgery and which may help reduce the risk of deep vein thrombosis (DVT).

THR Total hip replacement (total hip arthroplasty) Replacement of the femoral head with a stemmed femoral prosthesis and insertion of an acetabular cup, with or without cement.

Thromboprophylaxis Drug or other post-operative regime prescribed to patients with the aim of preventing blood clot formation, usually deep vein thrombosis (DVT), in the post-operative period.

Tibial component (knee) Portion of a knee prosthesis that is used to replace the articulating surface of the tibia (shin bone) at the knee joint. May be modular or monobloc (one piece).

Tibial component (ankle) Portion of an ankle prosthesis that is used to replace the articulating surface of the tibia (shin bone) at the ankle joint.

TKR Total knee replacement (total knee arthroplasty). Replacement of both tibial and femoral condyles (with or without resurfacing of the patella), with or without cement.

Total condylar knee Type of knee prosthesis that replaces the complete contact area between the femur and the tibia of a patient’s knee.

Treatment center Treatment centers are dedicated units that offer elective and short-stay surgery and diagnostic procedures in specialties such as ophthalmology, orthopaedic and other conditions. These include hip, knee, ankle, elbow, and shoulder replacements. Treatment centres may be privately funded (independent sector treatment centre – ISTC). NHS Treatment Centres exist but their data is included in those of the English NHS Trusts and Welsh Local Health Boards to which they are attached.

Trochanter Bony protuberance of the femur, found on its upper outer aspect.

Trochanteric osteotomy Temporary incision of the trochanter, used to aid exposure of hip joint during some types of total hip replacement.


Two-stage revision A revision procedure carried out as two operations, often used in the treatment of deep infection.

Type (of prosthesis) Type of prosthesis is the generic description of a prosthesis, e.g. modular cemented stem (hip), patellofemoral joint (knee), talar component (ankle), reverse shoulder (shoulder) and radial head replacement (elbow)

tendons – the tough cords of tissue that connect muscles to bones.

tibia – the shin bone.

tibial torsion – an inward twist of the shin bones, the bones that are located between the knee and the ankle. Tibial torsion causes the child’s feet to turn inward, or have what is also known as a “pigeon-toed” appearance. It is typically seen among toddlers.

torticollis (Also called wryneck.) – a twisting of the neck that causes the head to rotate and tilt on an angle.

trigger point – hypersensitive area or site in muscle or connective tissue, usually associated with myofascial pain syndromes.


Ulnar component (elbow) Part of a total elbow joint that is inserted into the ulna (inner lower arm bone) of the patient to replace the articulating surface of the ulna. May be linked or unlinked.

Uncemented See cementless.

Unicondylar arthroplasty Replacement of one tibial condyle and one femoral condyle in the knee, with or without resurfacing of the patella.


Unicondylar knee replacement See Unicondylar arthroplasty.

Unilateral operation Operation performed on one side only, e.g. left hip.

Unlinked total elbow Where the humeral and ulnar parts of a total elbow replacement are not physically connected


Varus / Valgus






x-ray – a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.

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