Indirect MR-arthrography in the follow up of autologous osteochondral transplantation

Abstract

To evaluate the spectrum of findings in indirect MR-arthrography following autologous osteochondral transplantation. 10 patients with autogenous osteochondral homografts underwent indirect MR-arthrography at three, 6 and 12 months postoperatively. The MR protocol at 1.5 T comprised unenhanced imagings with PD- and T2 -weighted TSE- sequences with and without fat-suppression as well as T1 -weighted fat-suppressed SE-sequences before and after i.v. contrast administration and after active joint exercise. Image analysis was done by two radiologists in conference and comprised the evaluation of signal intensity (Sl) and integrity of the osseous plug and the cartilage surface, as well as the presence of joint effusion or bone marrow edema. At three months, all cases demonstrated a significant bone marrow edema at the recipient and donor site that corresponded to a significant enhancement after i.v. contrast administration. The interface between the transplant and the normal bone showed an increased Sl at three and 6 months in T2 -weighted images as well as in indirect MR-arthrography. The marrow signal normalized in most cases after 6 to 12 months, indicating vitality and healing of the transplanted osteochondral graft. The Sl of the interface decreased in the same period, demonstrating the stability of the homograft at the recipient site. The osteochondral plugs were well-seated in 9/10 cases. Indirect MR-arthrography was superior to unenhanced imaging in the assessment of the cartilage surface. Cartilage coverage was complete in every case. The transplanted hyaline cartilage as well as the original cartilage showed a significant increase of the Sl in indirect MR-arthrography, that did not change in follow up studies. There were no pathological alterations of signal and thickness alterations of the transplanted cartilage in follow up investigations. Indirect MR-arthrography is a useful diagnostic tool following autologous osteochondral transplantation. Assessment of transplant vitality, osseous fixation and stability is possible.