Objective: Baker's cyst (BC) is also known as popliteal cyst. To evaluate its effect on intra-articular pathology, it is important to have the exact volume of the cyst. As BC may change its shape due to mass effect of the surrounding anatomic structures, it is difficult to measure the exact volume of BC. This study examined the relationship between three-dimensionally measured BC volume and symptomatic intra-articular knee pathologies.
Materials and methods: The magnetic resonance (MR) images of 45 patients with symptomatic knees were retrospectively examined.The BC volumes were measured via volumetric analysis. The joint effusion was examined in the sagittal plane in T2-proton density-weighted images. The medial plicae were assessed in accordance with the modified Sakakibara classification. Using the MR images, the meniscuses were classified in accordance with the meniscus rupture classification of Stoller et al. The cartilaginous lesions were analyzed using an MR grading system.In this study, correlations between the following measures were analyzed: BC volume and effusion level, medial plica presence, medial femoral condyle, medial tibial condyle, lateral femoral condyle and lateral tibial condyle cartilage degeneration, and medial meniscus anterior horn, medial meniscus posterior horn, lateral meniscus anterior and posterior horn ruptures.
Results: Cartilage degeneration, medial plicae, increase in intra-articular effusion, and increase in the BC volume were found to be statistically significant (p<0.01).
Conclusion: Cartilage degeneration, medial plicae, and increase in intra-articular effusion may increase the BC volume. We believe that this study may contribute to clinicians in understanding the relationship between BC volume changes and pathologies causing intra-articular knee symptoms.
Keywords: MRI; Popliteal cyst; knee joint; knee pain.