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 is a good Knee Society Score?

Scores of 80–100 are considered Excellent, 70–79 Good, 60–69 Fair, and below 60 Poor. Both the Knee Score and Function Score are interpreted independently on this scale.

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 occasional pain = 30, moderate occasional = 20, moderate continual = 10, severe pain = 0.

What deductions apply to the Function Score?

The Function Score starts at 100 and subtracts points for limited walking distance and inability to climb stairs. Using a cane, crutch, or walker also applies deductions of 5, 10, and 20 points respectively.

Is this the original or 2011 revised KSS?

This calculator implements the original 1989 Knee Society Clinical Rating System, which remains the most widely cited version in literature and the most commonly used in clinical practice.

Knee Society Score

Name: Knee Society Score
Availability: InStock
Author: Nham Vu

Calculate the Knee Society Score (KSS) from pain, stability, range of motion, and functional inputs to assess knee replacement outcomes.

Knee Score Inputs

Pain (max 50 pts)

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

degrees 24 pts

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 from neutral 0 pts

Optimal 0–4°: 0 deduction. Each degree beyond: −3 pts. Over 10° or varus: severe deduction.

Function Score Inputs

Walking Distance (max 50 pts)

Stair Climbing (max 50 pts)

Walking Aid (deduction)

Knee Score —

—

Function Score —

—

KSS Grading Reference

80–100

Excellent

70–79

Good

60–69

Fair

<60

Poor

Grading applies independently to both the Knee Score and the Function Score. Scores below 0 are clamped to 0.

Summary

Calculate the Knee Society Score (KSS) from pain, stability, range of motion, and functional inputs to assess knee replacement outcomes.

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 deductions for walking distance and stair climbing.
The calculator computes the Knee Score (0–100) and Function Score (0–100) separately with interpretation.

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: 2026-07-22 · Reviewed by Nham Vu