Introduction: MRI is considered to be highly effective in the diagnosis of internal derangement of the knee after acute trauma. 90–95% of meniscal and ligamentous injuries can be diagnosed by MRI and diagnostic arthroscopy can be effectively replaced with this modality. The drawbacks of MRI are its cost and availability. In recent years limited bone SPECT scan has been introduced as an alternative to MRI in the preoperative workup of patients with suspected meniscal and ligamentous injuries.
Purpose: To evaluate the diagnostic accuracy of bone SPECT in the pre-operative work up of patients with suspected meniscal tears.
Materials and Methods: 47 patients were included, average age was 41.9 years (range 18–78 years), 61.7% of the patients are male and 38.3% female. The results of limited bone SPECT scans of the knee were evaluated for accuracy as compared to the diagnosis established by knee arthroscopy, which is considered the gold standard for the diagnosis of meniscal tears.
Results: Bone SPECT scan of the knee was sensitive in 91.9% and specific in 20% of the cases compared to arthroscopy in the diagnosis of meniscal tears.
Positive predictive value calculated for SPECT is 81%, while the negative predictive value calculated is 40%. Separate calculations revealed a PPV of 90.5% in medial meniscal tears and a PPV of 86.7% in lateral meniscal tears respectively. In 13 cases additional inra-articular pathology was noted. In five cases the presumptive diagnosis of a meniscal tear on SPECT was rejected on arthroscopy, in three of these cases the anterior cruciate ligament was injured. One patient with a negative SPECT scan was operated and a meniscal tear found.
Discussion: The diagnostic accuracy of bone SPECT in suspected tears of the meniscus has not been fully validated. Our results correlate with results shown by other authors who reported a sensitivity of about 90 %. The value of the calculated specificity is difficult to interpretation, while patients with a negative SPECT scan are usually not operated. In these cases the SPECT scan should be compared to MRI results when available. In our setup bone SPECT should be included in the preoperative workup whenever the clinical diagnosis of a meniscal tear is doubtful until MRI becomes more readily available.
