Summary

The mean total ACTOCA score showed a linear correlation with clinical results in IKDC, Kujala, WOMET and Tegner scores, being highest at 24 months post-surgery.

Abstract

Introduction

Imaging assessment of bone aspects such as cystic changes and osseous integration is key to graft survival after FOCA transplantation.
As strong evidence is lacking as to whether magnetic resonance imaging (MRI) is reliable to correlate with clinical outcomes scores, a semi-quantitative assessment computed tomography osteochondral allograft (ACTOCA) scoring system was recently developed and validated.

Aim

To determine the correlation between the Assessment Computed Tomography Osteochondral Allograft (ACTOCA) scoring system and clinical outcomes scores.
The hypothesis was that the ACTOCA score would show sufficient correlation to support its use in clinical practice.

Method

We prospectively collected data from all consecutive patients who underwent cartilage restitution with fresh osteochondral allograft (FOCA) transplantation for osteochondral lesions of the knee and had a minimum follow-up of two years.
CT scans were performed at three, six and 24 months postoperatively. A musculoskeletal radiologist blinded to the patients’ medical history evaluated the scans using the ACTOCA scoring system.
Clinical outcomes collected preoperatively and at three, six and 24 months postoperatively were evaluated using the International Knee Documentation Committee (IKDC), Kujala, the Western Ontario Meniscal Evaluation Tool (WOMET) and the Tegner Activity Scale.
Descriptive statistics were used to determine patient and lesion characteristics. The results are given as a number of cases and/or percentage for categorical data, and as mean, standard deviation and range for quantitative data. Variables repeated during the trial (functional scales and CT) were analysed using ANOVA tests for repeated measures with Greenhouse–Geisser correction to avoid sphericity. The correlation between clinical results and imaging results was analysed by Pear- son’s correlation coefficient. The overall level of significance was set at 0.05 for two-sided tests. The power calculation was done according to IKDC from preoperative to 24 months postoperatively. A 5-point threshold for clinical relevance was set a priori. This number is in fact lower than multiple reported studies to detect minimal changes and similar to what was reported in a recent study by Magnuson et al. According to the power calculation, to generate a power of 80%, an alpha of 0.05, and a standard deviation of 10 points, this study required 30 patients.

Results

The mean total ACTOCA score showed a statistically significant correlation with the clinical outcome.
Correlation was optimal at 24 months. We found a high negative correlation with the IKDC, Kujala and Tegner (-0.737; -0.757 and -0.781 respectively) and a moderate negative correlation with WOMET (-0.566) (p<0.001).
IKDC, Kujala, WOMET and Tegner scores showed a significant continuous improvement in all scores (p<0.001).

Conclusion

The mean total ACTOCA score showed a linear correlation with clinical results in IKDC, Kujala, WOMET and Tegner scores, being highest at 24 months post-surgery.
This finding supports the use of ACTOCA to standardize CT scan reports following fresh osteochondral allograft transplantation in the knee.