Are articular cartilage lesions and meniscus tears predictive of IKDC, KOOS, and Marx activity level outcomes after anterior cruciate ligament reconstruction? A 6-year multicenter cohort study

Abstract

Background: Identifying risk factors for inferior outcomes after anterior cruciate ligament reconstruction (ACLR) is important for prognosis and future treatment.

Hypothesis: Articular cartilage lesions and meniscus tears/treatment would predict International Knee Documentation Committee (IKDC) score, Knee injury and Osteoarthritis Outcome Score (KOOS) (all 5 subscales), and Marx activity level at 6 years after ACLR.

Study design: Cohort study (prognosis); Level of evidence, 1.

Methods: Between 2002 and 2004, a total of 1512 ACLR patients were prospectively enrolled and followed longitudinally, with the IKDC, KOOS, and Marx activity score completed at entry, 2 years, and 6 years. A logistic regression model was built incorporating variables from patient demographics, surgical technique, articular cartilage injuries, and meniscus tears/treatment to determine the predictors (risk factors) of IKDC and KOOS scores and Marx activity level at 6 years.

Results: A minimum follow-up on 86% (1307/1512) of the cohort was completed at 6 years. The cohort was 56% male and had a median age of 23 years at the time of enrollment, with 76% reporting a noncontact injury mechanism. Incidence of concomitant injury at the time of surgery consisted of the following: articular cartilage (medial femoral condyle [MFC], 25%; lateral femoral condyle [LFC] 20%; medial tibial plateau [MTP], 6%; lateral tibial plateau [LTP], 12%; patella, 20%; trochlear, 9%) and meniscus (medial, 38%; lateral, 46%). Both articular cartilage lesions and meniscus tears were significant predictors of 6-year outcomes on the IKDC and KOOS. Grade 3 or 4 articular cartilage lesions (excluding patella) significantly reduced IKDC and KOOS scores at 6 years. The IKDC demonstrated worse outcomes with the presence of a grade 3 or 4 chondral lesion on the MFC, MTP, and LFC. Likewise, the KOOS score was negatively affected by cartilage injury. The sole significant predictor of reduced Marx activity level was the presence of a grade 4 lesion on the MFC. Lateral meniscus repairs did not correlate with inferior results, but medial meniscus repairs predicted worse IKDC and KOOS scores. Lateral meniscus tears left alone significantly improved prognosis. Small partial meniscectomies (<33%) on the medial meniscus fared worse; conversely, larger excisions (>50%) on either the medial or lateral menisci improved prognosis. Analogous to previous studies, other significant predictors of lower outcome scores were lower baseline scores, higher body mass index, lower education level, smoking, and anterior cruciate ligament revisions.

Conclusion: Both articular cartilage injury and meniscus tears/treatment at the time of ACLR were significant predictors of IKDC and KOOS scores 6 years after ACLR. Similarly, having a grade 4 MFC lesion significantly reduced a patient's Marx activity level score at 6 years.

Keywords: ACL reconstruction; IKDC; KOOS; Marx activity rating scale; anterior cruciate ligament; articular cartilage, meniscus; outcomes.

Figure 1

Flow Diagram of Study Cohort Legend: All anterior cruciate ligament reconstruction (ACLR) patients were enrolled during calendar years 2002-2004. Enrollment failures and patients not meeting inclusion criteria were removed leaving the eligible cohort as displayed. After removing those lost to follow up, the final number of study participants is shown.

Figure 2

Nomogram for IKDC model The outcome score, individualized for each patient based upon presenting characteristics, can be predicted by summing the point total for each variable on the left. To use the nomogram, place a ruler or straight edge vertically over each individual predictor listed on the left hand column, and use the top line (“Points”) to record the corresponding points assigned for that value. Repeat for each predictor variable listed along the left hand column. For example, a hypothetical patient with the following baseline demographics (in parentheses) would accumulate the corresponding number of points for each predictor variable for the IKDC:

1. Baseline IKDC score (50) = 59 points

2. Age at the time of surgery (20 yrs) = 5 pts

3. Sex (male) = 9 pts

4. Education (16 years) = 25 pts

5. Ethnicity (white) = 11 pts

6. BMI (25) = 29 pts

7. Baseline Marx (12) = 11 pts

8. Competition level (high school) = 2.5 pts

9. Main sport (football) = 17 pts

10. Smoking status at baseline (current) = 0 pts

11. Surgeon years of experience (10 yrs) = 2 pts

12. Year of surgery (2004) = 1 pt

13. Years since surgery (3 yrs) = 20 pts

14. Previous ACLR on contralateral knee (false) = 12.5 pts

15. Reconstruction type (revision) = 0 pts

16. Graft type (autograft) = 4 pts

17. Log odds on allograft (2) = 0 pts

18. Medial meniscus hoop stress fibers (intact) = 1 pt

19. Lateral meniscus hoop stress fibers (intact) = 0 pts

20. ACL graft source (hamstring) = 5 pts

21. Medial meniscus treatment (repair) = 2 pts

22. MFC chondromalacia grade (grade 2) = 27.5 pts

23. MTP chondromalacia grade (normal/grade 1) = 31 pts

24. Lateral meniscus treatment (no treatment) = 10 pts

25. LFC chondromalacia grade (grade 4) = 0 pts

26. LTP chondromalacia grade (normal/grade 1) = 7.5 pts

27. Patella chondromalacia grade (grade 2) = 0 pts

28. Trochlear chondromalacia grade (grade 2) = 8 pts

Manually sum these points, and using the ruler/straight edge, transfer the sum to the “Total Points” axis to determine the corresponding “Expected Value” at 6 years. For our hypothetical patient, the sum of the above variables equals 300 total points. Drawing a vertical line down from the “Total Points” mark at 300 to the “Expected Value” line at the bottom of the nomogram would correspond to a predicted 6 year IKDC value of 57.

Figure 3

Nomogram for KOOS Sports & Recreation subscale model The outcome score, individualized for each patient based upon presenting characteristics, can be predicted by summing the point total for each variable on the left. To complete the nomogram, the patient’s result is marked for each specific variable, and the point value based upon the “Points” line at the top of the scale is recorded. The sum of all of the points for each variable is then placed on the “Total Points” line at the bottom of the figure. The predicted outcome score at 6 years for the KOOS_sports/rec subscale is then read by drawing a perpendicular line below. BMI=body mass index; MFC=medial femoral condyle; LFC=lateral femoral condyle; MTP=medial tibial plateau; LTP=lateral tibial plateau.

Figure 4

Nomogram for KOOS Knee-Related Quality of Life subscale model The outcome score, individualized for each patient based upon presenting characteristics, can be predicted by summing the point total for each variable on the left. To complete the nomogram, the patient’s result is marked for each specific variable, and the point value based upon the “Points” line at the top of the scale is recorded. The sum of all of the points for each variable is then placed on the “Total Points” line at the bottom of the figure. The predicted outcome score at 6 years for the KOOS_qol subscale is then read by drawing a perpendicular line below. BMI=body mass index; MFC=medial femoral condyle; LFC=lateral femoral condyle; MTP=medial tibial plateau; LTP=lateral tibial plateau.

Figure 5

Nomogram for Marx Activity Rating Scale model The outcome score, individualized for each patient based upon presenting characteristics, can be predicted by summing the point total for each variable on the left. To complete the nomogram, the patient’s result is marked for each specific variable, and the point value based upon the “Points” line at the top of the scale is recorded. The sum of all of the points for each variable is then placed on the “Total Points” line at the bottom of the figure. The predicted outcome score at 6 years for the Marx activity level is then read by drawing a perpendicular line below. BMI=body mass index; MFC=medial femoral condyle; LFC=lateral femoral condyle; MTP=medial tibial plateau; LTP=lateral tibial plateau.