HOOS: The Hip Version of the Knee Questionnaire

What is the HOOS?

The HOOS is a patient-reported outcome measure — a standardized questionnaire that captures how your hip feels and functions from your point of view, not the surgeon's 1Ref 1Nilsdotter AK, Lohmander LS, Klässbo M, Roos EM (2003).Hip disability and osteoarthritis outcome score (HOOS)—validity and responsiveness in total hip replacement.The HOOS is a validated patient-reported outcome with five subscales (pain, symptoms, ADL, sport/recreation, hip-related quality of life) and is more responsive than WOMAC on pain and symptom subscales.. It was designed for people with hip osteoarthritis and for those having hip replacement, the two groups in whom hip pain and stiffness most often change over time 2Ref 2American Academy of Orthopaedic Surgeons (OrthoInfo) (2024).Osteoarthritis of the Hip.Hip osteoarthritis causes progressive groin and hip pain and stiffness and is initially managed nonsurgically.. The score reflects your experience of the joint.

A patient-reported outcome measure, or PROM, is filled in by the patient rather than scored by a clinician watching you move. The HOOS grew directly out of two older tools: the WOMAC osteoarthritis index, long used in arthritis research, and the KOOS, its knee counterpart. It actually contains the whole WOMAC inside it, so a clinician can still pull a WOMAC score out of the same set of answers. Its natural sibling is the KOOS questionnaire, which does for the knee exactly what the HOOS does for the hip 3Ref 3Roos EM, Roos HP, Lohmander LS, Ekdahl C, Beynnon BD (1998).Knee Injury and Osteoarthritis Outcome Score (KOOS)—Development of a Self-Administered Outcome Measure.The KOOS is the knee counterpart of the HOOS, a validated patient-reported outcome with the same five-subscale structure.. Osteoarthritis — the gradual wearing of joint cartilage that is the most common reason the HOOS gets used — is itself the most common form of arthritis 4Ref 4National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) (2023).Osteoarthritis.Osteoarthritis, the wearing of joint cartilage, is the most common form of arthritis..

What do the five HOOS subscales measure?

The HOOS is built from five separate subscales, each scored on its own: Pain, other Symptoms such as stiffness and catching, Function in daily living, Function in sport and recreation, and hip-related Quality of life 1Ref 1Nilsdotter AK, Lohmander LS, Klässbo M, Roos EM (2003).Hip disability and osteoarthritis outcome score (HOOS)—validity and responsiveness in total hip replacement.The HOOS is a validated patient-reported outcome with five subscales (pain, symptoms, ADL, sport/recreation, hip-related quality of life) and is more responsive than WOMAC on pain and symptom subscales.. They are reported separately rather than blended into one number, because a hip can hurt little yet still limit sport, or move well yet weigh heavily on your mind.

• Pain — how often and how severely the hip hurts, and which movements bring it on.
• Symptoms — stiffness, grinding, catching, and how far the hip will move.
• Function in daily living (ADL) — the ordinary business of stairs, socks, cars, and getting out of a chair. This is the WOMAC function items, carried over intact.
• Sport and recreation — squatting, running, twisting, and other higher demands that matter most to active people.
• Quality of life — how aware you are of the hip, how it limits your confidence, and how much it colors daily life.

Because each subscale stands alone, the HOOS can show that surgery fixed your pain while your confidence in the hip is still catching up — two true things a single number would hide.

How the HOOS is scored, and why higher is better

Each subscale is converted to a score from 0 to 100, where 100 means no symptoms or limitation and 0 means extreme problems 1Ref 1Nilsdotter AK, Lohmander LS, Klässbo M, Roos EM (2003).Hip disability and osteoarthritis outcome score (HOOS)—validity and responsiveness in total hip replacement.The HOOS is a validated patient-reported outcome with five subscales (pain, symptoms, ADL, sport/recreation, hip-related quality of life) and is more responsive than WOMAC on pain and symptom subscales.. This runs opposite to how many people assume a pain scale works, where a high number is bad. On the HOOS, a rising score over time is the goal — it means the hip is bothering you less and letting you do more.

The five subscale scores are usually reported side by side rather than added into a single grand total, because averaging them would blur exactly the differences the tool exists to show. The questionnaire takes most people about ten minutes, and it is designed so a scorer can handle a few skipped questions without throwing off the result. A score of 100 on every subscale describes a hip that causes no pain, no stiffness, and no limitation at all — a ceiling most healthy joints do not quite reach. That ceiling is worth knowing about, because it explains why an excellent recovery might still land in the 80s or 90s rather than a perfect 100.

A worked example: reading a set of HOOS scores

Imagine someone six months after a hip replacement whose HOOS reads: Pain 90, Symptoms 85, daily function 88, Sport and recreation 60, and Quality of life 78. Read together, those numbers tell a clear story: the operation has largely resolved the pain and the everyday tasks, while confidence and higher-demand activity are still catching up.

Before surgery, the same person's subscales might all have sat in the 30s and 40s — hurting, stiff, and limited across the board. The value is in the movement between the two sets of numbers, not in any single figure. A clinician reading the six-month scores would see nothing alarming in a Sport score of 60; that subscale is the last to recover and the hardest to max out, and 60 while everything else is high usually means the joint is fine and the demand is simply higher.

The pattern across the five subscales is the message — a low sport score sitting beside high pain and function scores reads very differently from a low pain score sitting beside everything else. This is exactly why the HOOS keeps the subscales separate. Collapsed into one average, this person might post a single number in the high 70s that hides both the excellent pain relief and the lagging confidence, and a clinician would lose the two facts most worth acting on. Read the five scores as a shape, and each rise or lag points to a specific piece of the recovery still in progress.

How the HOOS compares to the WOMAC and KOOS

The HOOS was built to keep everything useful about the older WOMAC while measuring more of what younger and more active hip patients care about. Because it embeds the full WOMAC, it stays comparable to decades of research, but it adds the sport, recreation, and quality-of-life questions the WOMAC lacks. On its original validation, the HOOS was more responsive than the WOMAC on the pain and symptom subscales — meaning it detected real change more sensitively 1Ref 1Nilsdotter AK, Lohmander LS, Klässbo M, Roos EM (2003).Hip disability and osteoarthritis outcome score (HOOS)—validity and responsiveness in total hip replacement.The HOOS is a validated patient-reported outcome with five subscales (pain, symptoms, ADL, sport/recreation, hip-related quality of life) and is more responsive than WOMAC on pain and symptom subscales..

The KOOS is the same instrument built for the knee: same five-subscale structure, same 0-to-100 scoring, same design philosophy 3Ref 3Roos EM, Roos HP, Lohmander LS, Ekdahl C, Beynnon BD (1998).Knee Injury and Osteoarthritis Outcome Score (KOOS)—Development of a Self-Administered Outcome Measure.The KOOS is the knee counterpart of the HOOS, a validated patient-reported outcome with the same five-subscale structure.. If you have arthritis in both a hip and a knee, you might be handed a HOOS for one and a KOOS for the other, and the two scores are read the same way. Neither tool competes with the other; they are regional dialects of one language for measuring joint problems from the patient's side.

What does a change in your HOOS score mean?

The HOOS earns its keep by being repeated. Filled out before a hip replacement and again three, six, and twelve months later, it turns a vague sense of "better" into a measured change on each subscale. A jump of several points that holds across visits is more trustworthy than a single high reading, which can reflect a good day rather than a real trend.

Not every point of change is meaningful. Small movements up and down are normal noise, and clinicians look for a change large enough to matter to you, not just large enough to measure. A shorter six-item version, the HOOS JR, was built specifically for tracking hip replacement outcomes at scale and rolls the most relevant items into a single number. When a registry reports a HOOS JR hip replacement score, it is using that streamlined form rather than the full HOOS, which is why hospitals and registries often prefer it for large-volume tracking. A score that dips at one visit is common and rarely means the hip is failing — the pattern across several visits is what counts.

There is a related idea clinicians rely on, sometimes called the smallest change worth noticing: the minimum shift in score that reflects a real difference to the patient rather than measurement noise. The exact figure varies by subscale and by the group studied, so rather than memorize a threshold, it helps to hold the principle — a couple of points is noise, a clear and sustained jump is signal. Your baseline score, taken at the very start, is what every later reading is measured against, which is why that first questionnaire matters as much as any that follow.

Where the HOOS fits into hip care

The HOOS is a measuring stick, not a treatment. It rides alongside whatever care you are getting, giving you and your clinician a shared number to watch. For hip osteoarthritis, guidelines put nonsurgical care first: exercise and physical therapy, weight management where relevant, and medications, with joint replacement reserved for hips that no longer respond 5Ref 5American Academy of Orthopaedic Surgeons (AAOS) (2023).Management of Osteoarthritis of the Hip — Clinical Practice Guideline.Hip osteoarthritis is managed with nonsurgical measures such as exercise and NSAIDs first, with joint replacement as a surgical option when those are exhausted.. Physical therapy for hip osteoarthritis centers on education, manual therapy, and exercise 6Ref 6Cibulka MT, Bloom NJ, Enseki KR, et al. (2017).Hip Pain and Mobility Deficits—Hip Osteoarthritis: Revision 2017.Physical therapy for hip osteoarthritis centers on patient education, manual therapy, and exercise..

Here the HOOS becomes genuinely useful. Tracking your subscales through a course of physical therapy shows whether the conservative sequence is working, and the same score gives you and your surgeon an objective before-and-after if you do move to replacement. The point of the HOOS is not to decide surgery for you — it is to make the effect of any treatment, surgical or not, visible over time. When exercise and other measures stop controlling pain and function, hip replacement is a well-established and effective option, and the HOOS is one of the tools used to confirm it delivered.

What the HOOS can and cannot tell you

The HOOS measures the impact of a hip problem; it does not name the problem. A low score tells you the hip is limiting your life, not whether the cause is osteoarthritis, a labral tear, impingement, or referred pain from the back. Only an examination and, when needed, imaging can do that. A questionnaire is a ruler, not a diagnosis — it measures how much, never what.

How carefully you complete it also shapes how useful the number is. Filling out a questionnaire like the HOOS for a typical week, rather than your best or worst day, keeps the score honest, and rushing through it quietly distorts the picture. Every region of the body has its own version of this idea — the Oswestry Disability Index for the low back, the Neck Disability Index for the neck, and the DASH questionnaire for the arm and shoulder — and none of them, the HOOS included, is meant to be self-diagnosis. Used the way it was designed, as a repeated, patient-reported yardstick, the HOOS is one of the clearest ways to see whether a hip is actually getting better.

That last point is the whole reason the HOOS exists. A scan can look unchanged while a hip feels dramatically better or worse, and a doctor's brief exam catches only a slice of a life lived with the joint. The HOOS fills that gap by asking the one person who knows how the hip actually behaves — the one living in it — the same questions, in the same words, again and again, so the answers can be compared instead of remembered.