Communication between the proximal tibiofibular joint and knee via the subpopliteal recess: MR arthrography with histologic correlation and stratigraphic dissection

OBJECTIVE. The anatomy and functional importance of the proximal tibiofibular joint (TFJ) have rarely been emphasized. Specifically, the detailed anatomic basis and MRI findings of the communication between the proximal TFJ and the knee have not been defined in the literature. To investigate such communication, anatomic and histologic correlation with MRI findings in frozen specimens and dissections of embalmed specimens was used in the study. MATERIALS AND METHODS. Twelve frozen knees were studied on MR arthrography. MR images of each specimen were compared with anatomic slices and histologic sample analysis. Dissection of an additional 28 embalmed specimens was performed to further investigate communication and the anatomy of the proximal TFJ. RESULTS. Communication between the proximal TFJ and the knee was observed in 27.5% of all anatomic specimens. It occurred via the subpopliteal recess and was related to a defect in the posterior ligament of the fibular head in all specimens. Evidence of an injury was apparent on MR images and was proven on histologic examination in 9% of the anatomic specimens that had such communication. CONCLUSION. The frequency of the communication between the proximal TFJ and knee via the subpopliteal recess related to a defect in the posterior ligament of the fibular head was found to be 27.5%. Evidence of an injury was present in 9% of anatomic specimens that had such communication. Injury to the posterior ligament of the fibular head and instability of the proximal TFJ may accompany a variety of knee injuries. Knowledge of the detailed anatomic appearance and MRI characteristics of the structures related to the proximal TFJ is key to identifying injuries to these structures.