MARX Knee PRO Measure

woman on couch holding her knee in pain

MARX Knee Score

The Marx Activity Rating Scale (MARS) was developed in 2001 as an outcome reporting measure to evaluate the activity level of patients with various knee disorders who participate in sports. The MARS focuses on four activity points: running, deceleration, cutting (changing directions while running) and pivoting.

Patients are asked to indicate approximately how many times in the past twelve months they performed each of these activities while at their healthiest and most active state. The four knee functions are rated on a 5-point scale of frequency and scores are added up to a maximum of sixteen points, with a higher score indicating more frequent participation.

The MARS is different from many other measures of activity because it is not based on participation in specific sporting activities. Instead, patients are asked about different components of physical function (e.g. running and pivoting) that are common to different sports. The goal of this instrument is to target the general activity level of the patient and not their most recent activity.

Strengths

The key strength of the Marx Activity Rating Scale is that it may be self-administered and takes approximately one minute to complete. This measure also asks patients about issues that are specifically relevant to them, such as giving-way, pain, locking of the knee and ability to run. In addition, studies have shown that there is a moderate correlation between Tegner Activity Scale (TAS) and the MARS outcome measure.

Considerations

There is a concern that the MARSrating scale does not adequately differentiate between patients who remain active in non-knee aggravating activities and those that give up sports entirely, creating a possible floor effect that requires investigation.

Additionally, since the MARS focuses on baseline activity frequency rather than current activity, the validity of the tool depends on how accurate the patient’s recall of their activity level is. Overall, the MARS is a short measure that can help evaluate patients who participate in sports, from recreational athletes to elite. As its main focus is on specific activities, the MARS is a tool that is most useful when paired with additional scales that assess other knee domains.

License and Cost

The MARX PRO Measure does not require a license and is free to use.

Sources | Assessing activity participation in the ACL injured population: a systematic review of activity rating scale measurement properties | Development and evaluation of an activity rating scale for disorders of the knee | The use of the Tegner Activity Scale for articular cartilage repair of the knee | Reliability and validity of

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