MPFL reconstruction using a quadriceps tendon graft. Part 1: Biomechanical properties of quadriceps tendon MPFL reconstruction in comparison to the Intact MPFL. A human cadaveric study

Herbort M., Hoser C., Domnick C., Raschke M., Lenschow S., Weimann A., Kösters C., Fink C.

Abstract

Background: The aim of this study was to analyze the structural properties of the original MPFL and to compare it to a MPFL-reconstruction-technique using a strip of quadriceps tendon. Methods: In 13 human cadaver knees the MPFLs were dissected protecting their insertion at the patellar border. The MPFL was loaded to failure after preconditioning with 10. cycles in a uniaxial testing machine evaluating stiffness, yield load and maximum load to failure. In the second part Quadriceps-MPFL-reconstruction was performed and tested in a uniaxial testing machine. Following preconditioning, the constructs were cyclically loaded 1000 times between 5 and 50. N measuring the maximum elongation. After cyclic testing, the constructs have been loaded to failure measuring stiffness, yield load and maximum load. For statistical analysis a repeated measures (RM) one-way ANOVA for multiple comparisons was used. The significance was set at P< 0.05. Results: During the load to failure tests of the original MPFL the following results were measured: stiffness 29.4. N/mm (+ 9.8), yield load 167.8. N (+ 80) and maximum load to failure 190.7. N (+ 82.8). The results in the QT-technique group were as follows: maximum elongation after 1000. cycles 2.1. mm (+ 0.8), stiffness 33.6. N/mm (+ 6.8), yield load 147.1. N (+ 65.1) and maximum load to failure 205. N (+ 77.8). There were no significant differences in all tested parameters. Conclusions: In a human cadaveric model using a strip of quadriceps-tendon 10. mm wide and 3. mm deep, the biomechanical properties match those of the original MPFL when tested as a reconstruction. Clinical relevance: The tested QT-technique shows sufficient primary stability with comparable biomechanical parameters to the intact MPFL.