KOOS, Knee injury and Osteoarthritis Outcome Score FAQs

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What is the KOOS?

The Knee injury and Osteoarthritis Outcome Score (KOOS) is a patient-reported outcome measurement instrument, developed to assess the patient’s opinion about their knee and associated problems. The KOOS evaluates both short-term and long-term consequences of knee injury and also consequences of primary osteoarthritis (OA). It holds 42 items in five separately scored subscales:

  1. KOOS Pain
  2. KOOS Symptoms
  3. Function in daily living (KOOS ADL)
  4. Function in Sport and Recreation (KOOS Sport/Rec), and
  5. Knee-related Quality of Life (KOOS QOL)

Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis, Ewa M Roos and L Stefan Lohmander. Health Qual Life Outcomes. 2003; 1: 64. Published online 2003 Nov 3. doi: 10.1186/1477-7525-1-64

Why assess health-related Quality of Life with the KOOS?

The main reason for developing a single instrument with the purpose of covering several types of knee injury and including osteoarthritis (OA) was that traumatic knee injuries often cause concomitant damage to multiple structures (ligaments, menisci, cartilage, etc.) and frequently lead to the subsequent development of OA.

To be able to follow patients after a trauma and to gain insight into the change in symptoms, function, etc. over time, a questionnaire, which covers both the short-term and long-term consequences is needed.

Prior instruments such as the Lysholm knee scoring scale have focused only on the short-term consequences, and instruments such as the WOMAC Osteoarthritis Index only on the long-term consequences. An instrument intended for use in follow-up evaluation of these patients needs to adequately monitor both the acute injury consequences in the physically active and younger patients, as well as the chronic outcomes in the elderly.

Roos and Lohmander 2003

What are the applications of the KOOS?

The KOOS is intended to be used over short and long time intervals — to assess changes from week to week induced by treatment (medication, surgery, physical therapy) or over the years due to a primary knee injury, post-traumatic OA or primary OA.

Roos and Lohmander 2003

In which populations can the KOOS be used?

KOOS has been used in patients 13-79 years of age.

KOOS is intended to be used for knee injury that can result in posttraumatic osteoarthritis (OA); i.e. knee ligament injury (ACL, posterior cruciate ligament [PCL], medial collateral ligament [MCL]), meniscal tears, knee cartilage lesions, knee OA, and osteochondritis dissecans, etc.

KOOS is meant to be used over short and long time intervals; to assess changes from week to week induced by treatment, examples include:

  • ligament reconstruction – ACL, PCL, MCL, meniscectomy, microfracture, osteochondral autografts, tibial osteotomy
  • knee replacement (TKR)
  • exercise (land-based, aquatic-based)
  • intra-articular sodium hyaluronate injection
  • pharmacologic therapy and glucosamine supplementation, or
  • over years due to the primary injury, post traumatic OA or primary OA

Roos and Lohmander 2003

How was the KOOS developed?

KOOS was developed by Ewa Roos and co-authors in the 1990s as an instrument to assess the patient’s opinion about their knee and associated problems.

Items were selected based on:

  • The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), version 3.0
  • a literature review
  • an expert panel (patients referred to physical therapy for knee injuries, orthopedic surgeons, and physical therapists from Sweden and the US, and
  • a pilot study of two questionnaires (one for symptoms of ACL injury, one for symptoms of OA) in individuals with post-traumatic OA

What are the KOOS subscales and what areas of health do they measure?

The KOOS collects data on five knee-specific patient-centered outcomes:

  1. KOOS Pain
  2. KOOS Symptoms: Other symptoms such as swelling, restricted range of motion and mechanical symptoms
  3. KOOS ADL: Disability on the level of daily activities
  4. KOOS Sport/Rec: Disability on a level physically more demanding than activities of daily living
  5. KOOS QOL: Quality of life, mental and social aspects such as awareness and lifestyle changes

Patient-Reported Outcome Instruments for Use in Patients with Articular Cartilage Defects, Ewa M. Roos, Luella Engelhart, Jonas Ranstam, Allen F. Anderson, Jay J. Irrgang, Robert G. Marx, Yelverton Tegner, and Aileen M. Davis. Cartilage. 2011 Apr; 2(2): 122–136. doi: 10.1177/1947603510391084

The Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis, Ewa M Roos and L Stefan Lohmander. Health Qual Life Outcomes. 2003; 1: 64. Published online 2003 Nov 3. doi: 10.1186/1477-7525-1-64

Patient-Reported Outcome Instruments for Use in Patients with Articular Cartilage Defects, Ewa M. Roos, Luella Engelhart, Jonas Ranstam, Allen F. Anderson, Jay J. Irrgang, Robert G. Marx, Yelverton Tegner, and Aileen M. Davis. Cartilage. 2011 Apr; 2(2): 122–136. doi: 10.1177/1947603510391084

Also see
OA knee brace clinic – knee pain relief and effective care
When Knees Need Support
Conservative biomechanical strategies for knee osteoarthritis

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