Knee Society Score (KSS)
Patient outcomes following a total knee arthroplasty (TKA) were traditionally determined by using objective measures, like the Knee Society Score (KSS). More recently, we’ve continued to see a rise in the use of quality-of-life measures instead, which provide greater emphasis on patient-specific evaluation.
Developed in 1989, the Knee Society Score (KSS) was originally an objective measure. But with shifting trends in 2011, it was expanded and updated to become a mixed outcome measure that is both objective (physician input) and subjective (patient input). According to its creators, the score prioritizes the patient perspective to better track patient expectations, satisfaction and activity levels than was possible with its predecessor.
The original version of the Knee Society Score does not directly translate to the 2011 KSS survey, and no conversion algorithm has been developed. This may hinder the ability of researchers to adopt the 2011 KSS while still maintaining their historical/longitudinal original KSS data.
The 2011 KSS measure includes a pre-operative and post-operative segment. In the pre-operative section patients are asked to supply demographic information and complete questions relating to their current symptoms, knee function, satisfaction with their pre-operative functional activities and the expectations they have based on the results of the TKA. The surgeon then completes information on objective measures such as joint alignment, instability, motions and symptoms.
The 2011 Knee Society Score can be used in conjunction with other outcome measures and has been found to be generally consistent with other knee-specific scores.
The 2011 version of the Knee Society Score is much improved with an emphasis on the patient perspective. Scores can be generated independently for each category and the measure also provides flexibility and depth to help capture the diverse lifestyles of a younger patient population. The Knee Society Scoring system has been validated and is broadly applicable across gender, age, activity level and implant type.
The KSS remains a complicated and clumsy reporting measure to administer. Each interval has different questions and requires both the clinician and the patient to complete an unreasonable amount of data entry within a rigid fashion, which takes much time and effort. Additionally, leaving a few blank answers may invalidate results as authors of the measure have suggested that it is not possible to provide a truly valid estimate of the score for any domain that has missing responses. This may result in spending an inordinate amount of time following up patients and require much administration.
Overall, the Knee Society Score is a valid and reliable measure that works well in certain situations, such as a prospective study that has a lot of structure and resources devoted to data collection or for assessing objective and subjective outcomes after total and partial knee arthroplasty. It is not a feasible measure to use as part of an ongoing patient reported outcomes program.
Licensing and Cost
Free. The KSS Score does not require a license. To learn more about the Knee Society Score, please visit their website: www.kneesociety.org/the-knee-society-score.