99mTc-methylene diphosphonate single photon emission tomography of the knees: intensity of uptake and its correlation with arthroscopic findings.

Objective To examine whether single photon emission computed tomography (SPECT) can determine the severity of knee pathology, based on intensity of uptake and, therefore, possibly substituting this technique for more invasive and expensive diagnostic procedures, such as arthroscopy, in certain patient populations. Methods The study results of patients referred for knee SPECT followed by an arthroscopy at our institution were evaluated retrospectively. The scintigraphic and arthroscopic findings for the menisci and femoral condyles were each graded on a numeric scale. One numeric scale corresponded to the level of uptake in the SPECT and the other to the severity of the pathology visualized at arthroscopy. Statistical correlation between both scales, representing the SPECT and arthroscopy findings, was performed. Results Forty-one patients were included in the study. A positive and statistically significant correlation was found between the intensity of uptake on the SPECT and the severity of the arthroscopic findings in the menisci and medial femoral condyle. Conclusion The degree of uptake in the knee, as determined by SPECT, positively correlates with the severity of pathology seen at arthroscopy. The data can potentially be used to assist in decision-making before proceeding to surgery, especially where there is severe pathology that may be less amenable to arthroscopic therapy.