[Reconstruction of the anterior cruciate ligament using the patellar tendon: its magnetic resonance evaluation].

MRI of the knee was performed in 30 patients who had been submitted to arthroscopically-guided reconstruction of the anterior cruciate ligament from patellar tendon. The autograft structure was investigated and MR results were correlated with clinical findings. Partial/total meniscectomy had been carried out in 21/30 cases. The patients were imaged at various postoperative intervals (3-24 months) by means of an 0.5-T magnet (GE MR Max Plus) in full knee extension and internal rotation. Sagittal and axial T1-weighted images (slice thickness: 3 mm) were combined with real-time reconstruction which better demonstrated the whole graft. T2-weighted coronal images (slice thickness: 5 mm) were also acquired. In each patient the following clinical variables were considered: anterior drawer sign, Lachman test, pivot shift, degree of leg extension, and finally functional recovery. The following MR variables were then considered: structure and alignment of bone tunnels, structure and signal intensity of the graft, degree of synovial inflammation, structure and signal intensity of the posterior cruciate ligament and finally structure of the menisci and/or meniscal residues. Symptoms-MR correlation suggests that the different outcome of surgical reconstruction may depend on the correct alignment of the tibial and femoral bone tunnels and on good meniscal condition. Bone tunnels must be located on the same plane, posterior and parallel to the slope of the intercondylar roof, since angulation causes the latter to impact the graft during knee extension, with inflammation and risk for rupture. As for menisci, tiny residues or total ablation overload tha graft, whose signal increases and whose synovia becomes inflamed. The latter pattern is always distinguished from that of the autograft, whose signal intensity seems not to change in time. In conclusion, MR proved an accurate and non-invasive technique to image this kind of postoperative knee, since metallic artifacts do not reach the joint space.