Essential knee terminology
Icing search for term

A knee may be 'iced' to limit inflammation and swelling.

ICRS search for term

ICRS is an abbreviation for 'International Cartilage Repair Society'.

IKDC search for term

IKDC is an abbreviation of 'International Knee Documentation Committee', and is a commonly used scoring system for knee problems.

Iliotibial band search for term

The iliotibial band is a thickened and strong tendinous strap which runs down the side of the thigh.

Page updated November 2023 by Dr Sheila Strover (Clinical Editor)

Iliotibial band friction syndrome search for term

Iliotibial band friction syndrome is an overuse disorder, where with exercise a person experiences pain on the outer side of the knee over the bony prominence called the femoral epicondyle.

Iliotibial band stretch search for term

An iliotibial band stretch is a knee rehabilitation exercise to stretch the fibrous band at the side of the thigh.

Page updated February 2024 by Dr Sheila Strover (Clinical Editor)

Iliotibial band syndrome search for term

The Iliotibial band syndrome is the same thing as 'iliotibial band friction syndrome'.

Immobiliser search for term

An immobiliser is a knee brace that keeps the leg in a straight position.

Immune response search for term

An immune response is a cellular and chemical reaction of the body to a foreign agent.

Impingement search for term

An Impingement is when a structure in the body interferes with the mobility of another structure by getting in the way.

In vitro search for term

In vitro ('within glass') means within laboratory equipment, such as test tubes and petri dishes, but it may also mean any laboratory model used for research, such as a mechanical simulator.

In vitro fertilisation search for term

In vitro fertilisation is the procedure of fertilising an egg outside of the body in a laboratory.

In vivo search for term

In vivo is some procedure performed within the living body. 

Incision search for term

An incision is a surgical cut.

Induced pluripotent stem cell search for term

Induced pluripotent stem cells are generated by reprogramming adult cells through the introduction of a small number of specific genes and giving them the ability to reproduce into multiple cell types. 

Inferior search for term

Inferior is a positional anatomical word meaning 'below'.

Inflammation search for term

Inflammation is a condition of distress of body tissues, where irritant chemicals are released and trigger a protective cellular response from the body.

Infrapatellar search for term

Infrapatellar means below the patella (kneecap).

Infrapatellar brace search for term

An infrapatellar brace is a firm elasticated tube which goes around the limb under the patella, to change the forces on the patellar tendon.


Infrapatellar bursitis search for term

Infrapatellar bursitis is an inflammation of the infrapatellar bursa, below the kneecap.

Infrapatellar contracture syndrome search for term

Infrapatellar contracture syndrome is a condition of excessive scarring behind the patellar tendon, in the infrapatellar area.

Page updated September 2023 by Dr Sheila Strover (Clinical Editor)

Infrapatellar plica search for term

The infrapatellar plica is a filmy structure - not always present - that stretches from the notch of the femur to the fat pad. It is also commonly referred to as the ligamentum mucosum.

Innervated search for term

Innervated means 'supplied by nerves'.

Innervation search for term

Innervation is the nerve supply of a structure.

Insall-Salvati Ratio search for term

The Insall-Salvati Ratio is the ratio of the length of the patellar tendon to the length of the patella, when measured on an X-ray or MRI with the knees bent to 30 degrees.

Inside-out technique search for term

The inside-out technique is a method of repairing a torn meniscus where the sutures are introduced from inside the joint and secured on the outside of the capsule.

Instability search for term

Instability in the knee is the feeling that you cannot confidently trust the joint, which may feel wobbly or give way suddenly, and the term may also apply to the kneecap which can sublux or dislocate.

Insufflation search for term

Insufflation is a technique to distend the space within the knee capsule in order to break down early adhesions and restore range of motion.

Intercondylar notch search for term

The intercondylar notch is the deep space in the knee between the two rounded ends (condyles) of the thighbone (femur).

Page updated June 2023 by Dr Sheila Strover (Clinical Editor)

Interference screw search for term

An interference screw is one that is used to hold a ligament graft firmly in the bone by actually running alongside the ligament tissue.

Intermuscular haematoma search for term

An intermuscular haematoma is bleeding in the tissue planes between muscles.

Internal brace search for term

An internal brace is a construct placed within the joint that supports a torn ligament while it heals after it has been surgically repaired.

Internal fixation search for term

Internal fixation is the procedure of repairing bones by fixing them with metal devices, for example a plate and screws.

International Cartilage Repair Society search for term

The International Cartilage Repair Society (ICRS) is a professional scientific and medical society.

International Patellofemoral Study Group search for term

The IPSG was founded in 1995 when "a group of friends" with proven interest in the academic study of patellofemoral problems agreed to meet informally to gain mutual understanding of the special issues and controversies related to the kneecap.

Intraarticular search for term

'Intra' ='within' and 'articular' ='the joint', so if something is intraarticular it means that it is within the cavity of the joint.

Intramedullary nail search for term

An intramedullary nail is a metal rod used for fractures of long bones, where the rod is driven through the centre part of the bones to hold them in good alignment so that they can heal properly.

Intramuscular search for term

Intramuscular means into the muscle (eg an injection) or inside the muscle (eg a bleed).

Intramuscular haematoma search for term

'Intra' -'within' and 'haematoma'='a confined lump of blood', so an intramuscular haematoma is bleeding within the muscle tissues.

IPP search for term

IPP is an abbreviation for infrapatellar plica.

IPP-Fat Pad Complex search for term

The IPP-Fat Pad Complex is the anatomical connection of the infrapatellar plica and the fat pad.

Page updated December 2023 by Dr Sheila Strover (Clinical Editor)

ISAR search for term

International Society of Arthroplasty Registers

Isokinetic machine search for term

An isokinetic machine is both an exercise device and a measuring device, that uses the principles of isokinetics.

Isokinetics search for term

Isokinetics is a form of exercise and muscle testing using an isokinetic machine - where the resistance of the machine changes so that the person exercises at a constant speed.

Isometric search for term

The term isometric comes from the Greek for "having equal measurement". A structure in the knee that is isometric has the same measurement irrespective of whether the knee is flexed( bended) or extended (straightened).

ITB search for term

Abbreviation of 'iliotibial band'.

ITBS search for term

Abbreviation of 'iliotibial band syndrome'.

IVF search for term

In vitro fertilisation - fertilising an egg in a laboratory.