Serial Magnetic Resonance Imaging Graft Signal Intensity and its Correlation with Functional Recovery Following Primary Anterior Cruciate Ligament Reconstruction.

INTRODUCTION: Anterior cruciate ligament (ACL) reconstruction is a widely used surgery to reestablish knee stability in case of ligament rupture. The process of healing of a graft is called ligamentization and is a dynamic biological process that can be measured through magnetic resonance imaging (MRI). The intensity of grafts signal as an MRI has been suggested as a non-invasive indicator of graft maturation, but the relationship of this parameter with functional recovery is currently under investigation. MATERIALS AND METHODS: This was a prospective observational study involving 50 patients who were aged between 18 and 45 years and had primary ACL reconstruction in a tertiary centre. The serial MRI measurements were conducted at 3, 6, and 12 months after the surgery to determine the graft signal intensity (low, intermediate, high). The international knee documentation committee (IKDC) and Lysholm knee scores were also used to measure the functional outcomes. Appropriate statistical techniques were used to compare MRI results with functional outcomes, with a significance level of P < 0.05. RESULTS: High signal intensity was observed in 52% of patients at 3 months, reducing to 28% and 12% at 6 months and 12 months, respectively, with low signal intensity rising at 12-56%, respectively. The functional results revealed that 40% of patients had excellent and 36% had good IKDC scores, and Lysholm scores were excellent in 44% and good in 32% of patients. Low signal intensity patients (12 months) had a significantly higher mean IKDC score (88.5 ± 4.2) than intermediate (76.3 ± 5.1) and high signal intensity patients (65.8 ± 6.4). The graft signal intensity was found to have a significant negative correlation with IKDC (r = -0.62, P < 0.001) and Lysholm scores (r = -0.58, P < 0.001). CONCLUSION: There was a strong correlation between serial MRI graft signal intensity and functional recovery after ACL reconstruction. Reduced signal strength was linked to improved functional performance, which demonstrates a superior level of graft maturation. MRI is potentially a useful non-invasive device to track graft healing and inform post-operative rehabilitation.