Summary

This 10-year follow-up study on ACL-reconstructed patients assesses the correlation between subjective PROs (KOOS, ACL-RSI) and objective MRI findings (WORMS, T1ρ, T2), revealing that favorable patient-reported outcomes often do not match the true condition of the knee joint, indicating a gap between perceived and actual knee health.

Abstract

Objective

Patient-reported outcomes (PROs) are commonly used for post-operative evaluations after ACL reconstruction. However, it is unclear whether these subjective assessments reflect the progression of knee joint degeneration, i.e., osteoarthritis progression, especially when evaluating long-term results. This study aimed to investigate the relationship between subjective PROs and the health status of the knee joint using MRI, including the WORMS score and quantitative MRI evaluations, T1ρ and T2 values, in patients 10 years post-ACL reconstruction.

Methods

This follow-up study involved patients who underwent ACL reconstruction at our institution between 2011 and 2014, as part of previous cohort studies. Thirteen patients who agreed to participate in the 10-year follow-up were included. The PROs used the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the ACL-Return to Sport after Injury (ACL-RSI) scale, while the Marx activity scale (MARX) was used for measuring physical activity levels. MRI methods included the semi-quantitative Whole-Organ Magnetic Resonance Imaging Score (WORMS) and cartilage compositional assessment. All images were acquired using a 3T MRI scanner with a 16-channel knee coil. Bilateral 3D proton-density fat-saturated fast-spin-echo and bilateral Magnetization-Prepared Angle-Modulated Partitioned k-Space Spoiled Gradient Echo Snap-shots sequences were acquired for morphological and compositional (combined T1ρ and T2) assessment, respectively. The postprocessing for T1ρ and T2 analysis was performed using in-house developed software with Matlab. We segmented cartilage manually and calculated the mean values in each of 6 regions; medial femur (MF), medial tibia (MT), lateral femur (LF), lateral tibia (LT), patella (PAT), and trochlea (TRO). Spearman test was performed to investigate the correlations. Statistical significance was set at p < .05.

Results

The median KOOS Pain, Symptoms, ADL, QOL, and Sports/Recreation were 97.2, 78.6, 98.5, 75, and 90, respectively. The median ACL-RSI scale was 66.1, the MARX was 6, and the WORMS total score was 8. ACL-RSI (p=0.02) and KOOS Pain (p=0.016) had positive correlations with the WORMS total score. For T1ρ analyses, a positive correlation was noted with KOOS Pain in LF (p=0.043), while a negative correlation was seen with MARX in LT (p=0.028). For T2 analyses, there were positive correlations in ACL-RSI with the T2 value in the MF (p=0.001), in KOOS-Pain with the T2 value in MF (p=0.003) and in MT (p=0.021), and a negative correlation in MARX with MARX in LF (p=0.020). In the relationship between the WORMS and quantitative MRI, the WORMS total was not associated with T1ρ values in any of the regions. However, the WORMS total correlated positively with T2 values in MF (p=0.002), MT (p=0.001), and LF (p = 0.04).

Discussion

Higher scores in ACL-RSI and KOOS pain were associated with worse knee conditions, indicating potential progression of knee OA without perceived pain or fear during sports. This suggests the need for caution in using patient-reported evaluations to assess structural knee health.

Conclusion

In patients 10 years post-ACL surgery, favorable patient-reported outcomes did not necessarily reflect the actual structural health status of the knee joint. Instead, there was a positive correlation between worse joint conditions and scores in ACL-RSI and KOOS pain.