Osteoarthritis is a common condition of the hip that affects millions of adults around the world and is a frequent cause of pain, functional disability and reduced quality of life. The Hip Disability and Osteoarthritis Outcome Score (HOOS) is a patient-reported outcome tool (PRO tool) that is used to evaluate patients following Total hip arthroplasty (THA).

The HOOS questionnaire was built upon the Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC) – an instrument that also measures outcomes in osteoarthritis and following THA. Questions from the WOMAC (LK version 3.0) were used as the basis for the HOOS survey and two additional dimensions were added: sport & recreation and hip-related quality of life [1].

To its advantage however, HOOS has been found to be more responsive than the WOMAC survey [1].

HOOS is composed of 40 questions and attempts to assess patient outcomes by looking at five sub-scales: Pain (10 items), symptoms (5 items), activity of daily living (17 items), sport and recreation function (4 items) and hip related quality of life (4 items). A total HOOS score is calculated by using a simple formula to produce a score that ranges from 0-100 with higher scores representing better function.

What’s the difference between HOS, HOOS, and HOOS Jr?

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The HOOS survey is easy to administer and relatively easy to score. The questionnaire is self-explanatory, user friendly and well-represented in literature. Additionally, because HOOS contains questions from the WOMAC, WOMAC scores may be calculated from a HOOS questionnaire. As a point of interest, HOOS is suggested to be more valuable than WOMAC for younger and more active patients due to the added subscales [3].

Another advantage of HOOS is that it may be used over short and long term intervals to asses changes induced by treatment (ie. medication, physical therapy, operation), primary injuries or post traumatic osteoarthritis [2].



HOOS takes approximately 10-15 minutes to complete, which some patients may find difficult. Additionally, HOOS has undergone psychometric testing with regards to assessing hip osteoarthritis, but needs further testing in different groups of patients with other hip disabilities.

Overall, HOOS is a well-regarded tool for the evaluation of patients following a THA. If the time required to complete the survey isn’t an issue, it’s a solid PRO tool to consider.



No license is required to use the HOOS survey. It may be obtained freely from http://www.koos.nu/



  1. Nilsdotter, A. K., Lohmander, L. S., Klässbo, M., & Roos, E. M. (2003). Hip disability and osteoarthritis outcome score (HOOS) – validity and responsiveness in total hip replacement. BMC Musculoskeletal Disorders, 4, 10. http://doi.org/10.1186/1471-2474-4-10, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC161815/
  2. Physiopedia. Hip Disability and Osteoarthritis Outcome Score. http://www.physio-pedia.com/Hip_Disability_and_Osteoarthritis_Outcome_Score
  3. Nilsdotter, A., & Bremander, A. (2011). Measures of hip function and symptoms: Harris hip score (HHS), hip disability and osteoarthritis outcome score (HOOS), Oxford hip score (OHS), Lequesne index of severity for osteoarthritis of the hip (LISOH), and American Academy of Orthopedic Surgeons (AAOS) hip and knee questionnaire. Arthritis care & research, 63(S11), S200-S207. http://onlinelibrary.wiley.com/doi/10.1002/acr.20549/pdf