Reference Values for the Marx Activity Rating Scale in a Young Athletic Population: History of Knee Ligament Injury Is Associated With Higher Scores.
BACKGROUND
Activity-related patient-reported outcome measures are an important component of assessment after knee ligament injury in young and physically active patients; however, normative data for most activity scales are limited.


OBJECTIVE
To present reference values by sex for the Marx Activity Rating Scale (MARS) within a young and physically active population while accounting for knee ligament injury history and sex.


METHODS
Cross-sectional study.


METHODS
Level 2.


METHODS
All incoming freshman entering a US Service Academy in June of 2011 were recruited to participate in this study. MARS was administered to 1169 incoming freshmen (203 women) who consented to participate within the first week of matriculation. All subjects were deemed healthy and medically fit for military service on admission. Subjects also completed a baseline questionnaire that asked for basic demographic information and injury history. We calculated means with standard deviations, medians with interquartile ranges, and percentiles for ordinal and continuous variables, and frequencies and proportions for dichotomous variables. We also compared median scores by sex and history of knee ligament injury using the Kruskal-Wallis test. MARS was the primary outcome of interest.


RESULTS
The median MARS score was significantly higher for men when compared with women (χ(2) = 13.22, df = 1, P < 0.001) with no prior history of knee ligament injury. In contrast, there was no significant difference in median MARS scores between men and women (χ(2) = 0.47, df = 1, P = 0.493) who reported a history of injury. Overall, median MARS scores were significantly higher among those who reported a history of knee ligament injury when compared with those who did not (χ(2) = 9.06, df = 1, P = 0.003).


CONCLUSIONS
Assessing activity as a patient-reported outcome after knee ligament injury is important, and reference values for these instruments need to account for the influence of prior injury and sex.
Keller Army Hospital, West Point, New York kenneth.l.cameron.civ@mail.mil.
Kenneth L
KL
Cameron
Keller Army Hospital, West Point, New York.
Karen Y
KY
Peck
United States Military Academy, West Point, New York.
Brandon S
BS
Thompson
Keller Army Hospital, West Point, New York.
Steven J
SJ
Svoboda
Keller Army Hospital, West Point, New York.
Brett D
BD
Owens
University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Stephen W
SW
Marshall
D000293:Adolescent; D000070598:Anterior Cruciate Ligament Injuries; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology*; D007718:Knee Injuries / Q000503:physiopathology; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D012016:Reference Values; D012307:Risk Factors; D012737:Sex Factors; D011795:Surveys and Questionnaires; D055815:Young Adult
activity scales; knee ligament injury; patient-reported outcome measures