Macroscopic anatomical, histological and magnetic resonance imaging correlation of the lateral capsule of the knee

Abstract

Purpose: The objective of the present study was to correlate macroscopic and microscopic anatomy of the lateral capsule of the knee joint with high-quality magnetic resonance imaging (MRI), with a hypothesis that a distinct lateral capsular ligament would be inconsistently observed via surgical dissection and that high-quality MRI imaging would correlate to findings from dissection.

Methods: Ten fresh-frozen human cadaveric knee specimens were utilized for this study. MRI of each knee was obtained pre- and post-dissection. The lateral knee was dissected and analysed for the presence or absence of a discrete capsular thickening or an independent ligamentous structure. A musculoskeletal radiologist analysed the pre- and post-dissection MRI. Subsequently, two specimens with positive lateral capsular thickening were prepared for histology.

Results: On macroscopic dissection, none of the ten specimens were found to have a discrete lateral capsular ligament. A palpable macroscopic thickening of the lateral capsule was identified in 4/10 specimens. MRI analysis revealed a 2-4 mm thickening of the central third of the lateral capsule in 3/10 specimens. On histological analysis, the lateral capsular thickening demonstrated properties similar to both capsule and ligament.

Conclusions: In fresh-frozen cadaveric specimens, macroscopic and MRI evaluation of the lateral capsule of the knee revealed variations in morphology without consistent capsuloligamentous anatomy and specifically no discrete lateral capsular ligament. Further investigation in the form of clinical and mechanical relevance of the lateral capsular structures is of paramount importance before limited anatomical data can be utilized to drive clinical decision-making and patient care.

Keywords: Anatomy; Anterolateral ligament; Knee; Lateral capsule.