Essential knee terminology
OA search for term

OA is an abbreviation of 'osteoarthritis'.

OATS search for term

OATS is an abbreviation for a procedure where a core of healthy cartilage and bone is taken from an unimportant area of the knee to replace a more important damaged area.

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

Occupational therapist search for term

An occupational therapist is a clinically-trained person who specialises in either aiding patients back to work or using work therapy as part of a treatment plan.

OCD search for term

OCD is an abbreviation of 'osteochondral defect'. The abbreviation is also used for 'osteochondritis dissecans'.

Oedema search for term

Oedema is excess fluid in the soft tissues.

Oedematous search for term

Oedematous is an adjective to describe body tissue that is boggy with excess tissue fluid.

Offloading search for term

Offloading is changing the forces through the knee joint to protect a damaged area.

One-legged balance search for term

One-legged balance is a knee rehabilitation exercise.

Online consultation search for term

An online consultation is a virtual meeting with a doctor facilitated by the internet. 

Open chain search for term

An exercise is 'open chain' when it involves a phase where the foot is free and not in contact with any surface.

Open chain exercise search for term

An 'open chain' exercise in one in which the end of the limb being exercised is free from contact with any surface for some part of the excursion.

Opening wedge search for term

An opening wedge describes a type of knee osteotomy for correcting limb alignment.

Opening-wedge osteotomy search for term

An opening-wedge osteotomy is a surgical procedure where a bone is cut partly through and wedged open, in order to re-angle the bone.

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

ORIF search for term

ORIF is an abbreviation for 'open reduction and internal fixation', and refers to bone fractures.

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

Orthobiologic search for term

An orthobiologic helps injuries to heal damaged bones, tendons, ligaments and muscle by using cell-based therapies and biological materials that will become part of the repaired but living tissue.

Orthopaedic search for term

The term 'orthopaedic' relates to the medical management of disorders of bones and soft tissues of the limbs.

Orthopaedic surgeon search for term

An orthopaedic surgeon is a specialist in surgery of the bones and soft tissues of the limbs.

Orthotic search for term

An orthotic is a shoe insert.

Orthotics search for term

Orthotics is the discipline of improving gait or leg stability with shoe inserts or knee braces.

Orthotist search for term

An orthotist is a clinician who specialises in optimising the forces through the feet via insoles of various shapes and custom footware.

OS search for term

OS is an abbreviation for 'orthopaedic surgeon'.

OSD search for term

Abbreviation of 'Osgood Schlatter's disorder'.

Osgood Schlatter's disease search for term

Osgood Schlatter's disease is an 'overuse' condition, where the attachment of the patellar tendon to the tibia bone becomes stressed.

Ossicle search for term

An ossicle is a very small bone.

Osteitis search for term

Osteitis is infection of the bone.

Osteoarthritis search for term

Osteoarthritis of the knee is the most common form of knee arthritis.

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

Osteoarticular transfer system search for term

The Osteoarticular Transfer System is surgical procedure to core out a damaged bit of joint cartilage and replace it with a healthy bit from a donor.

Osteochondral allograft search for term

An osteochondral allograft is transplant of a plug of bone and cartilage from a donor into a prepared matching defect in the patient.

Osteochondral Autologous Transfer System search for term

Osteochondral Autologous Transfer System (OATS) is a surgical procedure where a plug of bone and cartilage is cored from a relatively unimportant area of knee cartilage and used to replace damage to an important area.

Osteochondral defect search for term

An osteochondral defect occurs when a chunk of joint cartilage is lost, leaving a crater that extends into the underlying bone.

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

Osteochondral graft search for term

An osteochondral graft is plug of bone and cartilage that can be press-fitted into a prepared hole to replace a defect in the joint cartilage.

Osteochondritis search for term

Osteochondritis is inflammation of the joint cartilage and underlying bone.

Osteochondritis dissecans search for term

Osteochondritis dissecans is a destructive condition of bone, where blood supply becomes insufficient to a small section of cartilage and its underlying cartilage.

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

Osteochondrosis search for term

Osteochondrosis is a general term implying that there is some abnormal process going on in the joint cartilage and underlying bone.

Osteolysis search for term

Osteolysis is the breakdown of bone, which is a normal part of the self-restructuring of bone, but which can in some cases be abnormal and leave cavities in the area.

Osteomyelitis search for term

Osteomyelitis is a bone infection that also involves the bone marrow.

Osteonecrosis search for term

Osteonecrosis is cell death of a small area of bone.

Osteophyte search for term

An osteophyte (bone spur) is a small, irregular bony outgrowth from a joint surface, usually seen in relation to osteoarthritis.

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

Osteoporosis search for term

Osteoporosis is a disorder of thinning of bone, which may lead to fractures even after minor trauma.

Osteotomy search for term

Osteotomy is a surgical procedure where a bone is cut and realigned or repositioned to improve the forces going through the area.

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

OT search for term

OT is an abbreviation for 'occupational therapist'.

Outerbridge Classification search for term

The Outerbridge classification is a grading system for joint cartilage breakdown in the knee.

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

Outside-in technique search for term

The outside-in technique refers to meniscus repair where a needle is introduced into the knee from the skin through the two adjacent parts of torn meniscus, under arthroscopic visual control.

Overuse injuries search for term

Overuse injuries may occur when the knee is put through unusual repetitive motions.

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

Oxford knee score search for term

The Oxford Knee Score is a scoring system of activities of daily living. 0=poor, 48=good.