2017 ISAKOS Biennial Congress ePoster #1622

 

Biomechanical And Histological Differences Between Extra-Articular Knee Ligaments

Kristof Smeets, MD, PhD, Tongeren BELGIUM
Steven Claes, MD, PhD, Herentals BELGIUM
Joshua Slane, PhD, Leuven BELGIUM
Lennart Scheys, PhD, Prof., Leuven BELGIUM
Ramses Forsyth, MD, PhD, Ghent BELGIUM
Johan Bellemans, MD, PhD, Langdorp BELGIUM

ZOL Genk - UHasselt - KULeuven - UZ Leuven, Genk, Vlaanderen, BELGIUM

FDA Status Not Applicable

Summary

Ligaments are complex, heterogeneous structures that can be subdivided in different groups according to their biomechanical and histological properties. These data suggest that different groups of ligaments need a different treatment strategy.

Abstract

Introduction

Knee ligament injuries are very common and numerous reconstruction techniques have been described. Knowledge of ligament characteristics is necessary to enhance the effectiveness of various treatment procedures and to deal with problems such as overconstraining versus residual joint laxity. Differences between ligaments are described in their anatomy and function but no clear subdivision with regard to their specific biomechanical and histological properties has been provided.

Purpose

(1) To provide data on the biomechanical and histological properties of extra-articular knee ligaments.
(2) To explore the differences and similarities on those properties between the investigated structures
We hypothesize that ligaments are a heterogeneous groups with different material and histological characteristics.

Methods

Nine fresh-frozen human cadaveric knees (76±14 years, 6 male and 3 female ) were dissected for identifying the medial collateral ligament (MCL), the lateral collateral ligament (LCL), the anterolateral ligament (ALL), and the medial patellofemoral ligament (MPFL). Mechanical properties were determined during a single pull-to-failure test using a materials testing frame equipped with custom soft tissue clamps. From recorded force/displacement data, the elastic modulus (slope of the linear portion of the stress/strain curve), ultimate strength (stress at failure), ultimate strain (strain at failure), and strain energy density (area under the stress/strain curve) were calculated. Moreover, six fresh-frozen human cadavers were dissected for the same group of structures and were procured for histological analysis and elastin content.

Results

The elastic modulus was significantly higher (P < 0.05) for the MCL at 446±111 MPa relative to the LCL at 313±156 MPa and ALL at 190±91 MPa. The ultimate stress was of the MCL and LCL was not significantly different (74.7±19 MPa and 91.3±37.9 MPa, respectively; P > 0.05) but their ultimate strain values were (24±2 % and 40±11 %, respectively; P < 0.05). Both the MCL and LCL failed at a higher stress than the ALL and the MPFL (ultimate stress 49.8±16.7 MPa and 46.9±32.4, respectively; P < 0.05). The ultimate strain of the ALL (36±8 %) was significantly higher (P < 0.05) relative to the MCL and MPFL (21±4 %). The LCL (strain energy density 16.3±6.5 MPa) was able to absorb significantly more energy before failure (P < 0.05) relative to all other ligaments (MCL 7.9 ± 2.5 MPa, MPFL 4.7 ± 3.2 MPa, and ALL 8.2 ± 2.7 MPa). Histologically, a strong correlation could be seen between the LCL and ALL, both consisting of parallelly aligned collagen bundles, containing elastin bundles.

Conclusions

Ligaments are complex, heterogeneous structures that can be subdivided in different groups according to their biomechanical and histological properties. These data suggest that different groups of ligaments need a different treatment strategy.