Morphometric and Histological Analysis of the Ligamentum Mucosum of the Knee Joint: A Descriptive Study

Abstract

Background: The ligamentum mucosum (LM), or the infrapatellar plica, is a synovial fold of the knee joint that extends between the infrapatellar pad of fat and the intercondylar notch of the femur. LM has been implicated in plica syndrome, a painful knee condition caused by thickened, fibrotic, and edematous synovial plicae. LM can be used to reconstruct an anterior cruciate ligament tear. The present cadaveric study aims to describe the gross and histological features of LM. Methodology: In 20 adult cadavers, the intra-articular structures of the knee joint were exposed by reflecting the patella. LM and its type were identified. The length, width, and thickness were measured. The structure of LM was studied using hematoxylin and eosin stains. Results: LM was present in all the knees. Type 1 was predominant with a single band and was observed in 85%. Type 2a and type 2b were presented with double bands and triple bands, respectively. Type 3 LM was a vertical septum dividing the joint cavity into two compartments. The length of the ligament was 28.16 ± 2.35 mm. The thickness of LM at the proximal and distal end was higher on the left side, which was statistically significant. LM was composed of dense connective tissue and had rich vascularization. Conclusion: LM was initially thought to be incidental, but recent studies have changed the view, and the present study confirms its presence and describes its anatomical features. Knowledge about the LM is necessary to evaluate anterior knee pain when no other pathology is detected.