Abstract des Autors

A prospective study was performed to evaluate serial changes in the MRI signal and clinical stability of patellar bone - tendon - tibial bone autografts (PTB) for anterior cruciate ligament (ACL) reconstruction during the first 2 years. During the year 1994 in 63 ACL deficient knees the ruptured ACL was replaced by a PTB. 4 weeks, 3 months, 6 months, one year, and two years postoperatively 61 knees were evaluated by MRI and clinically to assess stability. For MRI evaluation a low-field dedicated system (0.2T ARTOSCAN, ESAOTE Italy) was used. T1- and T2 weighted sagittal and oblique coronal images were acquired for imaging the PTB. lt was known from an earlier arthroscopically controlled study that the low-field dedicated system provides sufficient image quality to evaluate PTB. The MR images were read by a MR-specialist, who did not know the orthopedic finding. In contrast, the orthopedic surgeon examining the operated knee did not know the MRI-report. 4 weeks postoperatively 90% of PTB retained a normal low MR signal. 3 months postoperatively 80%, 6 months postoperatively only 68%, 1 year postoperatively again 85%, and 2 years postoperatively 88 % of PTB showed a normal low MR signal. 14 (22%) PTB showed serial signal changes from low to increased, and again to low MR signal. 10% of PTB retained an increased MR signal over the whole two year follow-up period. A low MR signal did not correlate with a stable knee, as did not an increased signal intensity with a complicated result. The serial changes in MR signal of PTB are time-dependent. The clinical outcome should not be predicted based on the MR findings. Verf.-Referat