Longitudinal assessment of femoral knee cartilage quality using contrast enhanced MRI (dGEMRIC) in patients with anterior cruciate ligament injury - comparison with asymptomatic volunteers

Objective: In this observational longitudinal study we estimate knee joint cartilage glycosaminoglycan (GAG) content, in patients with an acute anterior cruciate ligament (ACL) injury, with or without a concomitant meniscus injury. Methods: 29 knees (19 men/10 women) were prospectively examined by repeat delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), approximately 3 weeks and 2.3 +/- 1.3 (range 4.5) years after the injury. We estimated the GAG content (T1Gd) in the central weight-bearing parts of the medial and lateral femoral cartilage and compared results with a reference cohort (n = 24) with normal knees and no history of injury examined by dGEMRIC at one occasion previously. Results: The healthy reference group had longer T1Gd values compared with the ACL-injured patients at follow-up both medially: 428 +/- 38 vs 363 +/- 61 ms (P < 0,0001) and laterally: 445 +/- 41 vs 396 +/- 48 ms (P= 0.0002). At follow-up T1Gd was lower in meniscectomized patients compared to those without a meniscectomy, both medially (-84 ms, P=0.002) and laterally (-38 ms, P=0.05). In the injured group, the medial femoral cartilage showed similar T1Gd at the two dGEMRIC investigations: 357 50 vs 363 61 ms (P=0.57), whereas the lateral femoral cartilage T1Gd increased: 374 48 vs 396 48 ms (P=0.04). Conclusions: The general decrease in cartilage T1Gd in ACL-injured patients compared with references provide evidence for structural matrix GAG changes that seem more pronounced if a concomitant meniscal injury is present. The fact that post-traumatic OA commonly develops in ACL-injured patients, in particularly those with meniscectomy, suggests that shorter T1Gd may be an early biomarker for OA. (C) 2011 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.