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

SummaryObjectiveIn 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.Methods29 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.ResultsThe 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).ConclusionsThe 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.