What is the Knee Society Score?

The Knee Society Score (KSS) is a standardized clinical scoring system developed to assess outcomes after total knee arthroplasty. It produces two separate subscores: the Knee Score (pain, stability, ROM) and the Function Score (walking distance, stair use).

What does the result mean?

This calculator reports the two historical raw scores separately. Interpretation depends on the clinical context, time point, and protocol; it does not apply an unsupported universal Excellent/Good/Fair/Poor label.

How is pain scored in the KSS?

Pain is the largest single component: no pain = 50 points, mild occasional pain = 45, mild stair pain = 40, mild pain with walking and stairs = 30, moderate occasional = 20, moderate continual = 10, severe pain = 0.

What deductions apply to the Function Score?

In the Function Score, walking distance (up to 50 points) and stair climbing (up to 50 points) contribute positive scores. Deductions apply only for walking aids: 5 points for a cane, 10 points for two canes, and 20 points for crutches or a walker.

Is this the original or 2011 revised KSS?

This calculator models the historical 1989 clinician-rated two-score system. It is not the copyrighted 2011 KSS, which has four subscales and should be obtained from The Knee Society.

Knee Society Score

Calculate the separate knee and function scores from the historical 1989 clinician-rated system. This is not the copyrighted 2011 KSS questionnaire.

Historical 1989 scoring workflow — not the 2011 KSS

Use clinician-assessed categories from the historical record. The current 2011 Knee Society Score is a different, copyrighted four-subscale instrument. Obtain its official forms and permissions from The Knee Society. This page is educational and is not a diagnosis or treatment recommendation.

Knee Score Inputs

Pain (max 50 pts)

Range of Motion (flexion arc) (max 25 pts)

degrees 24 pts

Enter a whole-degree clinician measurement. 1 point per 5° of motion (max 25 pts at 125°+).

Stability — Mediolateral (max 15 pts)

Stability — Anteroposterior (max 10 pts)

Knee Score Deductions

Flexion Contracture

Extension Lag

Alignment

degrees (+ valgus, − varus) 0 pts

Enter a whole degree. 5–10° valgus: no deduction. At 0–4° or 11–15° valgus: −3 pts per degree outside that range. Any varus or >15° valgus: −20 pts.

Function Score Inputs

Walking Distance (max 50 pts)

Stair Climbing (max 50 pts)

Walking Aid (deduction)

Knee Score —

Raw historical score; interpret clinically

Function Score —

Raw historical score; interpret clinically

Version and interpretation

The 1989 publication introduced separate knee and function scores so general infirmity would not lower the knee assessment. Compare scores only under a defined clinical or research protocol; this page does not assign a universal severity grade. Scores below 0 are displayed as 0.

Summary

Calculate the separate knee and function scores from the historical 1989 clinician-rated system. This is not the copyrighted 2011 KSS questionnaire.

How it works

Enter the pain score (0–50 points based on severity).
Enter stability scores for mediolateral and anteroposterior directions.
Enter the range of motion score based on degrees of flexion.
Enter functional scores for walking distance and stair climbing, along with any walking aid deductions.
The calculator reports the Knee Score (0–100) and Function Score (0–100) separately with a component breakdown.

Use cases

Orthopedic surgeons tracking patient outcomes after total knee arthroplasty.
Pre- and post-operative comparisons for knee replacement patients.
Clinical research and data collection for knee surgery studies.
Physical therapists monitoring functional recovery milestones.
Medical students learning knee outcome assessment methods.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu