title: Biomechanical Evaluation of Classic Solid and All-Soft Suture Anchors for Medial Patellofemoral Ligament Reconstruction.
abstract: BACKGROUND
  Multiple techniques for patellar fixation with classic solid suture anchors (SAs) in medial patellofemoral ligament (MPFL) reconstruction have been described. Fixation of the graft to the patella with all-soft suture anchors (ASAs) has not been studied. Purpose/Hypothesis: To evaluate the biomechanical performance of 2 different MPFL patellar fixation techniques: ASA fixation and SA fixation. We hypothesized that the ASA group would show no statistical difference in the ultimate failure load and stiffness compared with the SA group.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Reconstruction of the MPFL with gracilis autografts was performed in 16 fresh-frozen cadaveric knees (mean age, 52.6 ± 9.0 years). The specimens were randomly assigned to 2 groups of 8 specimens each based on the method used to fix the graft to the medial patella: ASA or SA fixation. Patellar fixation with ASAs was completed with 2 parallel 1.8-mm anchors (Q-Fix, Smith & Nephew). Fixation with SAs was completed with 2 parallel 2.9-mm anchors (Osteoraptor, Smith & Nephew). The reconstructions were cyclically loaded for 10 cycles to 25 N and then loaded in tension at 6 mm/s until failure. Ultimate failure load (N), displacement (mm), stiffness (N/mm), and mode of failure were recorded for each specimen.
  
  
  RESULTS
  Load to failure testing showed an ultimate failure load of 228.5 ± 53.1 N in the ASA group. In the SA group, the ultimate failure load was 156.2 ± 84.9 N. The difference between the 2 groups was not statistically significant ( P = .064). Stiffness values between the ASA and SA groups were not significantly different (21.3 ± 4.1 N/mm vs 20.9 ± 9.3 N/mm, respectively, P = .905). The most common mode of failure in both groups was anchor pullout (8 of 8 in the ASA group; 6 of 8 in the SA group).
  
  
  CONCLUSIONS
  This experimental study showed no statistically significant differences in biomechanical performance between 1.8-mm ASAs and 2.9-mm SAs.
  
  
  CONCLUSIONS
  Patellar fixation with 2 parallel ASAs may provide adequate patellar fixation for MPFL reconstruction, while their smaller diameter could potentially decrease the risks for patella fracture and violation of the articular surface in the cadaver model.
authors.affiliation: Seattle Children's Hospital, Seattle, Washington, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Saper
authors.affiliation: Texas Sports Medicine and Orthopaedic Group, Dallas, Texas, USA.
authors.forename: Karim
authors.initials: K
authors.lastname: Meijer
authors.affiliation: Andrews Research and Education Foundation, Gulf Breeze, Florida, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Winnier
authors.affiliation: Center for Orthopedic Research, Michigan State University, East Lansing, Michigan, USA.
authors.forename: John
authors.initials: J
authors.lastname: Popovich
authors.affiliation: Andrews Institute for Orthopaedics & Sports Medicine, Gulf Breeze, Florida, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Andrews
authors.affiliation: Andrews Institute for Orthopaedics & Sports Medicine, Gulf Breeze, Florida, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Roth
mesh_terms: D001696:Biomechanical Phenomena; D002102:Cadaver; D004867:Equipment Design; D005260:Female; D006801:Humans; D008023:Ligaments, Articular / Q000502:physiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000601:surgery; D057071:Patellofemoral Joint / Q000502:physiology* / Q000601:surgery*; D011897:Random Allocation; D053441:Suture Anchors; D013710:Tendons / Q000637:transplantation*; D014182:Transplantation, Autologous
keywords: MPFL; biomechanics; knee; patella; reconstruction