A cadaveric study for anatomical characterization of the superficial medial collateral ligament: the transition zone of metaphysis to diaphysis in TKA

Abstract

Purpose

The sMCL is pivotal for valgus stability and rotational control, with a critical role in maintaining and achieving knee stability in the native knee and after Total Knee Arthroplasty (TKA). This study aims to describe the detailed anatomical features of the superficial medial collateral ligament (sMCL) allowing surgeons to know the insertion points, if needed for reconstruction or to determine the transition of the metaphyseal to the diaphyseal zone in TKA and revision TKA.

Methods

We dissected 25 knees from 14 cadavers on whom TKA was simulated during this experiment to meticulously measure the anatomical dimensions of the sMCL, including its length, femoral origin, and tibial insertion points. Measurements were taken by two independent observers, ensuring reliability through the assessment of inter- and intra-observer variability using the intraclass correlation coefficient (ICC).

Results

The sMCL exhibited a mean length of 9.71 cm, with femoral origin and tibial insertion distances averaging 3.25 cm and 6.29 cm, respectively from the joint line. High ICC values confirmed the reliability of the measurements, although slight interobserver variability (P = 0.046) underscored the necessity for precise measurement techniques or possible difference in opinion about the identified surface landmark amongst the observers. This anatomical quantification provides essential references for surgical planning and execution of TKR.

Conclusion

The anatomical insights gained from this study show that the sMCL is a medial structure of about 9 cm with a femoral insertion point at 3 cm from the joint line and a tibial insertion point at 6 cm from the joint line. This knowledge can help surgeons in the development and understanding of classification systems based on epi-, meta- and diaphyseal zones, in the choice of the level of constraint and the zones of fixation, both in primary and revision TKA.