The detection of graft viability is challenging in the multiligament reconstructed knee. Magnetic resonance imaging gives structural information but lacks the capability to assess biological activity of the grafts. ¹⁸F-labeled fluorodeoxyglucose positron emission tomography combined with computer tomography is shown to be a sensitive method for imaging tissue metabolism and viability. The aim of the present study was to evaluate the feasibility of fluorodeoxyglucose positron emission tomography combined with computer tomography imaging in the detection of the replacement graft metabolism in multiligament reconstructed knees.

Seven patients (17-44 years) with multiligament reconstructed knee underwent fluorodeoxyglucose positron emission tomography combined with computer tomography to evaluate the biological activity of replacement grafts. The degree of fluorodeoxyglucose uptake reported as standard uptake values from the region of interest was analyzed 3-24 months postoperatively.

In all patients, the fluorodeoxyglucose positron emission tomography combined with computer tomography showed increased fluorodeoxyglucose uptake in all replacement grafts at different follow-up time points. Furthermore, fluorodeoxyglucose was higher at femoral condyles of operated knees compared to contralateral reference values.

This pilot study shows a significant increase in tendon graft metabolism during two first years of postoperative healing. The fluorodeoxyglucose positron emission tomography combined with computer tomography imaging seems to be adequate method of assessment of graft metabolism and viability during postoperative healing. The clinical value of fluorodeoxyglucose positron emission tomography combined with computer tomography imaging, however, warrants further evaluation with longitudinal studies with a larger patient population.