title: A double button adjustable loop device is biomechanically equivalent to tension band wire in the fixation of transverse patellar fractures-A cadaveric study.
abstract: BACKGROUND
  Tension-band wire fixation of patellar fractures is associated with significant hardware-related complications and infection. Braided polyester suture fixation is an alternative option. However, these suture fixations have higher failure rates due to the difficulty in achieving rigid suture knot fixation. The Arthrex syndesmotic TightRope, which is a double-button adjustable loop fixation device utilizing a 4-point locking system using FibreWire, may not only offer stiff rigid fixation using a knotless system, but may also obviate the need for implant removal due to hardware related problems. The aim of our study is to compare the fixation rigidity of patella fractures using Tightrope versus conventional tension-band wiring (TBW) in a cadaveric model.
  
  
  METHODS
  TBW fixation was compared to TightRope fixation of transverse patella fractures in 5 matched pairs of cadaveric knees. The knees were cyclically brought through 0-90° of motion for a total of 500 cycles. Fracture gapping was measured before the start of the cycling, and at 50, 100, 200 and 500 cycles using an extensometer. The mean maximum fracture gapping was derived. Failure of the construct was defined as a displacement of more than 3mm, patella fracture or implant breakage.
  
  
  RESULTS
  All but one knee from each group survived 500 cycles. The two failures were due to a fracture gap of more than 3mm during cycling. There was no significant difference in the mean number of cycles tolerated. There was no implant breakage. There was no statistical significant difference in mean maximum fracture gap between the TBW and TightRope group at all cyclical milestones after 500 cycles (0.3026±0.4091mm vs 0.3558±0.7173mm, p=0.388).
  
  
  CONCLUSIONS
  We found no difference between the TBW and Tightrope fixation in terms of fracture gapping and failure. With possible lower risk of complications such as implant migration and soft tissue irritation, we believe tightrope fixation is a feasible alternative in fracture management of transverse patella fractures.
authors.affiliation: Department of Orthopaedic Surgery, University Orthopaedics, Hand & Reconstructive Microsurgery Cluster, National University Hospital, National University Health System, Singapore.
authors.forename: Fucai
authors.initials: F
authors.lastname: Han
authors.affiliation: Department of Orthopaedic Surgery, Ng Teng Fong General Hospital, Jurong Health Services, Singapore; Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Christopher Jon
authors.initials: CJ
authors.lastname: Pearce
authors.affiliation: Department of Biomechanical Engineering, National University of Singapore, Singapore.
authors.forename: David Q K
authors.initials: DQ
authors.lastname: Ng
authors.affiliation: Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Amit K
authors.initials: AK
authors.lastname: Ramruttun
authors.affiliation: Engineering Cluster, Singapore Institute of Technology, Singapore.
authors.forename: Desmond Y R
authors.initials: DY
authors.lastname: Chong
authors.affiliation: Department of Orthopaedic Surgery, University Orthopaedics, Hand & Reconstructive Microsurgery Cluster, National University Hospital, National University Health System, Singapore.
authors.forename: Diarmuid
authors.initials: D
authors.lastname: Murphy
authors.affiliation: Department of Orthopaedic Surgery, University Orthopaedics, Hand & Reconstructive Microsurgery Cluster, National University Hospital, National University Health System, Singapore. Electronic address: chin_tat_lim@nuhs.edu.sg.
authors.forename: Chin Tat
authors.initials: CT
authors.lastname: Lim
authors.affiliation: Department of Orthopaedic Surgery, Ng Teng Fong General Hospital, Jurong Health Services, Singapore.
authors.forename: Bernard C S
authors.initials: BC
authors.lastname: Lee
mesh_terms: D001696:Biomechanical Phenomena; D001864:Bone Wires; D002102:Cadaver; D005593:Fracture Fixation, Internal / Q000295:instrumentation; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D010329:Patella / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D011091:Polyesters; D013314:Stress, Mechanical; D013536:Suture Techniques / Q000295:instrumentation*; D013537:Sutures
chemical_list: D011091:Polyesters
keywords: Adjustable loop device; Complications of tension band wire; Patella fracture; Tension band wire; Tightrope