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Biomechanical comparison of single- and double-bundle medial patellofemoral ligament reconstruction

View Article: PubMed Central - PubMed

ABSTRACT

Background: Recurrent patellar dislocation is common clinically, primarily in adolescents. However, the biomechanical properties of single- and double-bundle medial patellofemoral ligament (MPFL) reconstruction remain poorly understood.

Methods: Six fresh frozen adult cadaveric knee specimens were obtained for this study. Each specimen was fixed at 0° to test the force needed when the patella was laterally shifted 10 mm at a speed of 0.5 mm/s, and the test was repeated three times. This test was repeated when knee flexion was at 0°, 15°, 30°, 45°, 60°, and 90°. All six specimens were tested in four statuses, including MPFL intact, MPFL torn, single-bundle MPFL reconstruction, and double-bundle MPFL reconstruction.

Results: Similar force is required in these MPFL statuses at 0° of flexion, except for the MPFL torn group with a smaller force (45.5 ± 9.6 N, p < 0.05). The force required in the MPFL torn group reduced from 12.8 to 38.8% compared to other groups, at 0°, 15°, 30°, and 45° of flexion angles. At the flexion of 15°, the double-bundle reconstruction group required a statistically greater force (85.9 ± 10.1 N) compared to the single-bundle reconstruction group (74.0 ± 7.9 N). Interestingly, no statistical difference was found at flexions of 60° and 90° in these four groups.

Conclusions: Both single-bundle and double-bundle MPFL reconstruction can restore the stability of the patella. The double-bundle reconstruction has an angular synergy effect that simulates the MPFL wide footprint in the patella, which enables it to have greater capacity to resist patellar dislocation before the patella entering the femoral trochlea at a smaller flexion angle.

No MeSH data available.


Force collected by the biomechanical material dynamic mechanical testing system. a Overview of the testing system. b The experimental setup
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Fig1: Force collected by the biomechanical material dynamic mechanical testing system. a Overview of the testing system. b The experimental setup

Mentions: Six fresh frozen adult cadaveric knee specimens were obtained for this study. These specimens were comprised of 15-cm distal femurs, 15-cm proximal tibias, and their surrounding soft tissue structures. The average ages of the subjects were 57 ± 8 years old (range 48–72 years old). Cadaveric specimens had no prior surgery to the knee joint area. Deformities and apparent kinematic alterations when extended and flexed were not observed in these specimens. All operations were performed by one experienced orthopedist. A midline incision of the knee joint was performed, and the skin and subcutaneous fat were resected, retaining the ligament structures, joint capsules, and distal quadriceps. In order to remove the tibial and femoral bone marrow tissue, electric drill reaming was performed. Thus, a 9-mm diameter iron screw (the length of both the distal femur and proximal tibia was 20 cm) was inserted into the pulp cavity after drying. Then, polymethyl methacrylate (PMMA) was used for the fixation of the screw (Fig. 1).Fig. 1


Biomechanical comparison of single- and double-bundle medial patellofemoral ligament reconstruction
Force collected by the biomechanical material dynamic mechanical testing system. a Overview of the testing system. b The experimental setup
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5304392&req=5

Fig1: Force collected by the biomechanical material dynamic mechanical testing system. a Overview of the testing system. b The experimental setup
Mentions: Six fresh frozen adult cadaveric knee specimens were obtained for this study. These specimens were comprised of 15-cm distal femurs, 15-cm proximal tibias, and their surrounding soft tissue structures. The average ages of the subjects were 57 ± 8 years old (range 48–72 years old). Cadaveric specimens had no prior surgery to the knee joint area. Deformities and apparent kinematic alterations when extended and flexed were not observed in these specimens. All operations were performed by one experienced orthopedist. A midline incision of the knee joint was performed, and the skin and subcutaneous fat were resected, retaining the ligament structures, joint capsules, and distal quadriceps. In order to remove the tibial and femoral bone marrow tissue, electric drill reaming was performed. Thus, a 9-mm diameter iron screw (the length of both the distal femur and proximal tibia was 20 cm) was inserted into the pulp cavity after drying. Then, polymethyl methacrylate (PMMA) was used for the fixation of the screw (Fig. 1).Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Background: Recurrent patellar dislocation is common clinically, primarily in adolescents. However, the biomechanical properties of single- and double-bundle medial patellofemoral ligament (MPFL) reconstruction remain poorly understood.

Methods: Six fresh frozen adult cadaveric knee specimens were obtained for this study. Each specimen was fixed at 0° to test the force needed when the patella was laterally shifted 10 mm at a speed of 0.5 mm/s, and the test was repeated three times. This test was repeated when knee flexion was at 0°, 15°, 30°, 45°, 60°, and 90°. All six specimens were tested in four statuses, including MPFL intact, MPFL torn, single-bundle MPFL reconstruction, and double-bundle MPFL reconstruction.

Results: Similar force is required in these MPFL statuses at 0° of flexion, except for the MPFL torn group with a smaller force (45.5 ± 9.6 N, p < 0.05). The force required in the MPFL torn group reduced from 12.8 to 38.8% compared to other groups, at 0°, 15°, 30°, and 45° of flexion angles. At the flexion of 15°, the double-bundle reconstruction group required a statistically greater force (85.9 ± 10.1 N) compared to the single-bundle reconstruction group (74.0 ± 7.9 N). Interestingly, no statistical difference was found at flexions of 60° and 90° in these four groups.

Conclusions: Both single-bundle and double-bundle MPFL reconstruction can restore the stability of the patella. The double-bundle reconstruction has an angular synergy effect that simulates the MPFL wide footprint in the patella, which enables it to have greater capacity to resist patellar dislocation before the patella entering the femoral trochlea at a smaller flexion angle.

No MeSH data available.