Knee scores and calculators
15 knee instruments, grouped by what they do. Each carries its scoring formula in full, published clinically important thresholds where they exist, and its copyright status.
Conditions covered
ACL injury · Acute knee injury · Ankle sprain · Anterior cruciate ligament tear · Articular cartilage defect of the knee · Cartilage defect · Cartilage injury · Chondral and osteochondral lesions · Chondral lesion · Chondromalacia patellae · Hip osteoarthritis · Hip pain · Intra-articular knee fracture · Knee fracture · Knee instability · Knee ligament injury · Knee osteoarthritis · Knee trauma · Lower limb musculoskeletal disorder · Meniscal injury · Meniscal tear · Osteoarthritis · Patella alta · Patella baja · Patellar fracture · Patellar instability · Patellofemoral pain · Post-operative knee rehabilitation · Post-operative lower limb rehabilitation · Post-traumatic knee injury · Tibial plateau fracture
Patient-reported outcome measure8
- ACL-RSI12 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.
- IKDC18 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.
- KOOS42 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 Survey25 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.
- LEFS20 itemsLower Extremity Functional ScaleThe LEFS is a 20-item patient-reported questionnaire that measures difficulty with everyday lower limb activities on a single 0 to 80 scale, where 80 indicates no difficulty and a change of 9 points is the smallest difference patients reliably notice.
- Lysholm8 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.
- Marx4 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.
- Tegner1 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.
Clinical calculator2
- Caton-Deschamps2 itemsCaton-Deschamps IndexThe Caton-Deschamps index is the ratio of the distance from the inferior pole of the patellar articular surface to the anterosuperior corner of the tibial plateau, divided by the length of the patellar articular surface, where 0.6 to 1.2 is normal, above 1.2 is patella alta and below 0.6 is patella baja.
- Insall-Salvati2 itemsInsall-Salvati IndexThe Insall-Salvati index is the ratio of patellar tendon length to patellar length measured on a lateral knee radiograph; a ratio between 0.8 and 1.2 is normal, above 1.2 indicates patella alta, and below 0.8 indicates patella baja.
Classification system3
- Kellgren-Lawrence1 itemsKellgren-Lawrence Classification of OsteoarthritisThe Kellgren-Lawrence classification grades radiographic osteoarthritis from 0 to 4 based on osteophyte formation, joint space narrowing, subchondral sclerosis and bone contour deformity, with grade 2 conventionally taken as the threshold for definite radiographic osteoarthritis.
- Outerbridge1 itemsOuterbridge Classification of Chondral LesionsThe Outerbridge classification grades articular cartilage damage from 0 to IV at arthroscopy, progressing from normal cartilage through softening, fissuring under and over 1.3 centimetres in diameter, to full-thickness erosion exposing subchondral bone.
- Schatzker1 itemsSchatzker Classification of Tibial Plateau FracturesThe Schatzker classification sorts tibial plateau fractures into six types by the plateau involved and the fracture pattern, where types I to III involve the lateral plateau and carry a better prognosis, and types IV to VI are higher-energy injuries with medial, bicondylar or metaphyseal-diaphyseal involvement.
Clinical decision rule2
- Ottawa Knee Rule5 itemsOttawa Knee RuleThe Ottawa Knee Rule determines whether an acute knee injury requires radiographs using five criteria — age 55 or over, isolated patellar tenderness, fibular head tenderness, inability to flex to 90 degrees, and inability to bear weight for four steps — and is close to 99% sensitive for clinically significant fractures.
- Pittsburgh Knee Rules3 itemsPittsburgh Knee RulesThe Pittsburgh Knee Rules indicate a knee radiograph after blunt trauma or a fall when the patient is younger than 12 or older than 50, or cannot walk four weight-bearing steps in the emergency department — and the rule does not apply at all to any other mechanism of injury.