Biomechanical evaluation of three patellar fixation techniques for MPFL reconstruction: Load to failure did not differ but interference screw stabilization was stiffer than suture anchor and suture-knot fixation

• Published in: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA sports traumatology, arthroscopy : official journal of the ESSKA, 2021-11, Vol.29 (11), p.3697-3705
• Main Authors: Raoulis, Vasilios A., Zibis, Aristidis, Chiotelli, Maria Dimitra, Kermanidis, Alexis T., Banios, Konstantinos, Schuster, Philipp, Hantes, Michael E.
• Format: Article
• Language: English
• Subjects: Biomechanics; Bone implants; Cadavers; Cyclic loads; Drilling; Failure analysis; Failure load; Failure modes; Fixation; Grafts; Interference; Knee; Knots; Mean; Medicine; Medicine & Public Health; Orthopedics; Patella; Reconstruction; Rigidity; Sports Medicine; Statistical analysis; Stiffness; Sutures; Tunnels; Ultimate loads
• ISSN: 0942-2056; 1433-7347
• DOI: 10.1007/s00167-020-06389-4

Purpose The purpose of this study was to compare the maximum load to failure and stiffness of three medial patella-femoral ligament (MPFL) reconstruction techniques: (i) suture anchor fixation (SA), (ii) interference screw fixation (SF), and (iii) suture knot (SK) patellar fixation. The null hypothesis was that the comparison between these three different patella fixation techniques would show no difference in the ultimate failure load and stiffness. Methods Reconstruction of the MPFL with gracilis tendon autograft was performed in 12 pairs of fresh-frozen cadaveric knees (24 knees total; mean age, 63.6 ± 8.0 years). The specimens were randomly distributed into 3 groups of 8 specimens; SA reconstruction was completed with two 3.0-mm metal suture anchors; (SF) fixation was accomplished by two 6-mm bio-composite interference screws; SK fixation at the lateral side of the patella was accomplished after drilling two semi-patellar tunnels with a diameter of 4.5 mm. The reconstructions were subjected to cyclic loading for 10 cycles to 30 N and tested to failure at a constant displacement rate of 15 mm/min using a materials-testing machine (MTS 810 Universal Testing System). The final load of failure (N), stiffness (N / mm) and failure mode was recorded in each specimen and followed by statistical analysis. Results There was no significant difference in mean ultimate failure load among the three groups. The SK group failed at a mean ( ± SD) ultimate load of 253.5 ± 38.2 N, the SA group failed at 243 ± 41.9 N and the SF group at 263.2 ± 9.06 N. The SF group had a mean stiffness of 37.8 ± 5.7 N/mm. This was significantly higher ( p