title: Biomechanical evaluation of physeal-sparing fixation methods in tibial eminence fractures.
abstract: BACKGROUND
  Tibial eminence fractures occur most commonly in skeletally immature children. Several techniques using physeal-sparing fracture fixation have been described, but their structural properties have not been evaluated.
  
  
  OBJECTIVE
  To determine the strength and resistance to displacement of physeal-sparing techniques used to fix tibial eminence fractures.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Skeletally immature porcine knees were randomized into 4 treatment groups: (1) ultra-high molecular weight polyethylene suture-suture button (UHMWPE/SB), (2) suture anchor, (3) polydioxanone suture-suture button (PDS/SB), and (4) screw fixation. A prospective analysis of bone mineral density using dual-energy x-ray absorptiometry was performed on all specimens. Fracture fragments were created in a standardized manner and measured for size comparison. After fracture fixation, biomechanical testing was performed with cyclical and load-to-failure protocols by loading the tibia with an anterior shear force.
  
  
  RESULTS
  In load-to-failure testing, screw fixation had a significantly lower median peak failure load (186.4 N; lower quartile [LQ], 158.4 N; upper quartile [UQ], 232.6 N) than did UHMWPE/SB (465.8 N; LQ, 397.8 N; UQ, 527.8 N), suture anchors (440.5 N; LQ, 323.0 N; UQ, 562.3 N), and PDS/SB (404.3 N; LQ, 385.9 N; UQ, 415.6 N). UHMWPE/SB demonstrated a significantly higher median yield load (465.8 N; LQ, 397.8 N; UQ, 527.8 N) than did PDS/SB (306.7 N; LQ, 271.4, N; UQ, 405.7 N) and screw fixation (179.0 N; LQ, 120.2 N; UQ, 232.5 N). During cyclical testing, screw fixation demonstrated significantly lower percentage survival of specimens (0%) compared with the other groups (UHMWPE/SB, 100%; suture anchor, 78%; PDS/SB, 78%). After 1000 cycles of loading, PDS/SB fixation had significantly more median creep (6.76 mm; LQ, 6.34 mm; UQ, 8.28 mm) than did UHMWPE/SB (4.43 mm; LQ, 3.80 mm; UQ, 4.73 mm) and suture anchor fixation (3.06 mm; LQ, 2.59 mm; UQ, 4.28 mm). The lowest median stiffness was observed in the PDS/SB group (48.6 N/mm; LQ, 45.3 N/mm; UQ, 54.2 N/mm). UHMWPE/SB fixation demonstrated a significantly higher median peak failure load after cyclic testing (469.0 N; LQ, 380.6 N; UQ, 507.2 N) than did PDS/SB (237.7 N; LQ, 197.3 N; UQ, 298.3 N) and screw fixation (132.4 N; LQ, 123.7 N; UQ, 180.9 N). Suture anchor fixation had significantly more variance, as demonstrated by width of interquartile range, in peak failure load, yield load, and creep than did other techniques.
  
  
  CONCLUSIONS
  Physeal-sparing fixation of tibial eminence fractures with UHMWPE suture-suture button is biomechanically superior to both PDS suture-suture button and a single screw at the time of surgery and provides more consistent fixation than do suture anchors.
  
  
  CONCLUSIONS
  Suture anchors provide inconsistent fixation for tibial eminence fractures.
authors.affiliation: Tennessee Orthopaedic Alliance/The Lipscomb Clinic, St Thomas Medical Plaza, Suite 1000, 4230 Harding Road, Nashville, TN 37205, USA. canders6@comcast.net
authors.forename: Christian N
authors.initials: CN
authors.lastname: Anderson
authors.forename: Jeffry S
authors.initials: JS
authors.lastname: Nyman
authors.forename: Kirk A
authors.initials: KA
authors.lastname: McCullough
authors.forename: Yanna
authors.initials: Y
authors.lastname: Song
authors.forename: Sasidhar
authors.initials: S
authors.lastname: Uppuganti
authors.forename: Kevin R
authors.initials: KR
authors.lastname: O'Neill
authors.forename: Allen F
authors.initials: AF
authors.lastname: Anderson
authors.forename: Warren R
authors.initials: WR
authors.lastname: Dunn
mesh_terms: D000818:Animals; D015519:Bone Density; D005593:Fracture Fixation, Internal / Q000379:methods*; D006132:Growth Plate; D007718:Knee Injuries / Q000601:surgery*; D011897:Random Allocation; D013536:Suture Techniques; D013552:Swine; D013978:Tibial Fractures / Q000601:surgery*; D016474:Weight-Bearing
keywords: ACL avulsion; biomechanics; fracture; physeal sparing; skeletally immature; tibial eminence; tibial spine