1. Izaguirre A, Olivos A, Ibarra C, Marx R.
Validity and reliability of the Marx Activity Rating Scale in patients from Mexico City.
Izaguirre A, Olivos A, Ibarra C, Marx R.

2. Background
The number of outcome rating scales to measure patient function related to knee injury has increase in the past years.
Lysholm and Knee injury and Osteoarthritis Outcome Score (KOOS), are disease specific questionnaires.
When evaluating patients with knee diseases, besides measuring functionality, the level of activity is an important variable of interest.
Marx RG .Am J Sports Med 2001.

3. Background The Marx activity scale.
This instrument is a patient reported instrument, which is completed in approximately 1 minute, which facilitates its use with other instruments.
Running
Cutting
Deccelerating
Pivoting
Marx RG .Am J Sports Med 2001.

4. Purpose This useful instrument is not available for use in Spanish.
Therefore, the purpose of this study was to perform a cross-cultural adaptation of the Marx activity scale into Spanish, and to evaluate validity, floor and ceiling effect, and reliability of this version in Mexican patients with knee injuries.

5. Methods Cross-Cultural Translation.
Two orthopedic surgeons from Mexico, independently translated the Marx Activity Scale to Spanish.
This provisional Spanish version was translated back to English by a qualified translator (mother tongue Spanish and fluent in English) and a clinical director (mother tongue English and fluent in Spanish).
This back translation was reviewed against the source by the developers of Marx Activity Scale in order to check for discrepancies.
The final Spanish was tested on ten patients with knee injuries to assess problems of comprehension of the questionnaire content.

6. Methods Patients
After approval of the Institutional Review Board, one-hundred patients with knee injuries were enroled to this study.
The sample ws recruited in the outpatient clinic of the Service of Sports Orthopedic Surgery and Arthroscopy of the National Rehabilitation Institute, of Mexico City, Mexico.
Inclusion criteria were:
Age between 18 to 50 years,
Any gender,
Diagnosis of ACL lesion,
Menisci lesion,
Chondral lesion,
Patellar dislocation, osteoarthritis.
Exclusion criteria were:
Inflammatory arthritis
Inability of understand
Spanish written language.

7. Methods Patients
Before patients were seen by their orthopedic surgeons at consult,
Lysholm
Tegner
KOOS
International Knee Documentation Committee Subjective scale
Spanish version of the Marx Activity scale were administered.

8. Methods Scales:The Lysholm score
First described in 1982.
The score was designed to be physican administered and measure outcomes after knee ligament surgery .
8 items which include, limp, support, locking, instability, pain, swelling, stair climbing and squatting.
Lysholm 1982 Am J Sports Med 1982

9. Methods Scales: The Tegner Activity Score
11 items with a a scoring range of 0-10; with higher scores representing higher levels of physical activity.
6-10 corresponds to participation in competitive/or recreational sports,
1 to 5 corresponds to participation in recreational sports and light to moderate heavy labors,
and 0 is recorded for disability. (4)
Tegner Y, Lysholm J. Clin Orthop Relat Res

10. Methods Scales: KOOS 42 item Disease-specific questionnaire:
Pain (9 items)
Symptoms (7 items)
Activities of daily living (17 items)
Sport and Recreation (5 items)
Knee related Quality of Life (4 items). (7)
Roos EM, Toksvig-Larsen S. Health Qual Life Outcomes. 2003

11. Methods Marx Activity Scale
The Spanish version of Marx Activity Scale consists of 4 items
It relates to the frequency with which the patient, runs, cuts, pivots and decelerates.
Its score ranges from 0 to 16 with higher score representing higher activity level.
Marx RG .Am J Sports Med 2001.

12. Reproducibility.
20 healthy individuals with 18 to 50 years of age were submitted twice to the questionnaire (2 weeks)
For all the cases the activity level remained constant while taking both questionnaires.

13. Construct Validity.
Patients with high Spanish Marx Activity Scale scores would score higher Tegner Values.
Patients with high Spanish Marx Activity Scale scores would score higher KOOS Sports and recreation values.
For divergent validity, the Spanish Marx Activity Scale would correlate with patient age inversely.

14. Statistical Analyses.
The intraclass correlation coefficient (ICC) was used to asses the instrument test-retest reliability. (0.8 good reliability)
Spearman’s coeffient for correlations.
Strong correlation for values >0.5
Moderate correlation for values between 0.31 and 0.5
Weak correlations when < 0.31.

15. Results Translation Process.
During forward and backward translations, no major modification were made by the translators.
In the pilot study no item was found to cause confusion by the respondents.

16. Results Demographics 100 patients for construct Validity.
Mean age was ± 12.4.
64 % were men compared to 36 women
ACL lesion in 40 patients
Meniscus lesion in 15 patients
Osteoarthritis in 31 patients
Patelofemoral disorders in 14 patients.

17. Results Reproducibility
The intraclass correlation coefficient of the Spanish version of the Marx Activity Scale was of 0.8.
Test (n=20)
Retest (n=20)
ICC (95% CI)
Spanish Version of the Marx Activity Scale
5.8 ± 3.75
6.5± 3.2
0.80 ( )

18. Construct Validity Positive moderate correlations
KOOS pain
Symptoms
ADL
Lysholm
Tegner IKDC subjective form.
Moderate negative correlation
age.
KOOS Pain
KOOS
Symptoms
ADL
Sport/Rec
QoL
Lysholm
IKDC-S
Tegner
Age
Marx Activity Scale
0.357
p<0.001
0.359
0.315
0.183
p=0.06
0.04
p=NS
0.312
0.002
0.295
p=0.003
0.344
p=0.001

19. Discussion
The Spanish version of the Marx Activity scale has appropriate psychometric properties in terms of reliability, construct validity and ceiling and floor effects.
With regard to construct validity, the Marx Activity scale had moderate correlation between KOOS in the subcales of pain, symptoms, activities of daily living.
Spanish version of the Marx Activity scale does not correlate with the Sports and Recreation Subscale of KOOS.

20. Discussion
Moderate positive correlation with the Tegner further confirms construct validity.
This spanish version had a floor effect of 29%, close to the 33% margin set beforehand. Patients were studied preoperatively

21. Gracias