Knee
ACL injury
ACL injury outcomes are tracked with a knee-specific symptom score alongside an activity-level scale, because a good symptom score in a patient who has stopped pivoting sport is not the same result as the same score in one who has returned to it.
What you are actually deciding
Always pair a symptom measure with an activity measure. Reporting a KOOS or Lysholm without a Tegner or Marx score conceals whether the patient has improved or simply avoided the activities that provoke symptoms.
Patient-reported outcome measure7
- ACL-RSI Calculator12 itemsAnterior Cruciate Ligament – Return to Sport after Injury scaleThe ACL-RSI is a 12-item questionnaire of the psychological readiness to return to sport after anterior cruciate ligament injury — confidence, fear of re-injury and emotional response — with each item rated 0 to 10 and the mean expressed out of 100, where a higher score means greater readiness.
- IKDC Calculator18 itemsInternational Knee Documentation Committee Subjective Knee Evaluation FormThe IKDC Subjective Knee Evaluation Form is an 18-item patient-reported questionnaire covering knee symptoms, sports and daily activity and current knee function, whose raw total is transformed to a 0 to 100 score where 100 means no symptoms and no activity limitation — it requires permission from the AOSSM, so the items are not reproduced here.
- KOOS Calculator42 itemsKnee injury and Osteoarthritis Outcome ScoreThe KOOS is a 42-item patient-reported questionnaire that scores knee function as five separate subscales — Symptoms, Pain, Activities of Daily Living, Sport and Recreation, and Quality of Life — each from 0 (extreme problems) to 100 (no problems).
- Knee Outcome Survey Calculator25 itemsKnee Outcome Survey — Activities of Daily Living Scale and Sports Activity ScaleThe Knee Outcome Survey is a patient-reported measure of knee function with two scales — a 14-item Activities of Daily Living Scale and an 11-item Sports Activity Scale — each item scored 5 to 0 and expressed as a percentage of the maximum, so that 100% means no symptoms and no functional limitation.
- Lysholm Calculator8 itemsLysholm Knee Scoring ScaleThe Lysholm Knee Scoring Scale is an eight-domain questionnaire that rates knee symptoms and function — limp, support, locking, instability, pain, swelling, stair climbing and squatting — on a 0 to 100 scale, where 95 and above is graded excellent, 84 to 94 good, 65 to 83 fair, and below 65 poor.
- Marx Calculator4 itemsMarx Activity Rating ScaleThe Marx Activity Rating Scale measures how frequently a patient runs, cuts, decelerates and pivots in their healthiest state over the past year, scoring each on a 0 to 4 frequency scale for a total of 0 to 16, where a higher score means a more demanding activity level.
- Tegner Calculator1 itemsTegner Activity ScaleThe Tegner Activity Scale is a single-item ordinal ladder that grades a patient's work and sport activity from 0 (sick leave or disability pension because of knee problems) to 10 (national or international elite competitive sport), and is normally recorded twice — the pre-injury level and the current level — so that the drop between them can be reported.
Thresholds that apply here
Published change thresholds across the instruments above. Check the population matches your patient before using a value — a threshold derived in a different cohort will mislead you.
| Instrument | Type | Value | Subscale | Population |
|---|---|---|---|---|
| KOOS | MCID | 8–10 points | Pain | Total knee arthroplasty |
| KOOS | MCID | 8–10 points | ADL | Total knee arthroplasty |
| KOOS | MCID | 10 points | All subscales | ACL reconstruction |
| KOOS | PASS | ~78 points | Pain | Knee arthroplasty |
| KOOS | PASS | ~63 points | QOL | Knee arthroplasty |
| KOOS | MDC | 6–12 points | Varies by subscale | Knee osteoarthritis |
| Lysholm | MCID | 8.9 points | — | Patients with chondral disorders of the knee |
| Marx | MDC | 4.4 points | — | Patients with knee disorders |
| Tegner | MCID | 1 activity level | — | Patients with anterior cruciate ligament injury |
See the full threshold database for every instrument on the site.