title: The effect of annular repair on the failure strength of the porcine lumbar disc after needle puncture and punch injury.
abstract: OBJECTIVE
  The purpose was to quantify the structural integrity of annulus fibrosis (AF) after injuries with repair.
  
  
  METHODS
  Punctures in the AF of 6-month-old porcine spine specimens were made with 18-, 20-, 22-, 24-, and 26-gauge needles. Leakage testing was performed immediately after needle puncture (Group 1), after the puncture was repaired with a modified purse-string suture (MPSS) (Group 2), and after needle puncture with immediate repair (Group 3). Punch injuries repaired with the MPSS alone, or with an AF graft and MPSS were also examined.
  
  
  RESULTS
  There was no leakage from 26-gauge needle punctures. Pressures at which the nucleus pulposus leaked from the 24-, 22-, 20- and 18-gauge needle punctures (Group 1) were 4.28, 2.03, 1.27, and 1.06 MPa, respectively. Failure pressure after repair (Group 2, 3) was significantly greater than without (Group 1). Failure pressure in Group 3 was much greater than in Group 2 with 18- and 20-gauge punctures. Punch injury repaired with a graft and MPSS had significantly greater failure pressure than repair with MPSS alone (1.88 vs. 1.02 MPa, p = 0.0001).
  
  
  CONCLUSIONS
  The MPSS can restore the mechanical integrity of the AF after needle puncture. An annular graft along with a MPSS may increase the structural integrity of the AF after a punch injury. As this was an acute animal study, the measurements and results may not directly translate to the human intervertebral disc.
authors.affiliation: Department of Orthopaedics, Wan-Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chih-Hong
authors.initials: CH
authors.lastname: Yang
authors.affiliation: Department of Orthopaedics, Taichung Tzu Chi Hospital, Taichung, Taiwan.
authors.forename: Yueh-Feng
authors.initials: YF
authors.lastname: Chiang
authors.affiliation: Department of Orthopaedics, Shuang Ho Hospital, Taipei Medical University, No.291, Zhongzheng Rd., Zhonghe District, New Taipei City, 23561, Taiwan.
authors.forename: Chia-Hsien
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of Orthopaedics, Shuang Ho Hospital, Taipei Medical University, No.291, Zhongzheng Rd., Zhonghe District, New Taipei City, 23561, Taiwan.
authors.forename: Lien-Chen
authors.initials: LC
authors.lastname: Wu
authors.affiliation: Orthopedic Device Development Center, Industrial Technology Research Institute, Hsinchu, Taiwan.
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Liao
authors.affiliation: Department of Orthopaedics, Shuang Ho Hospital, Taipei Medical University, No.291, Zhongzheng Rd., Zhonghe District, New Taipei City, 23561, Taiwan. cjchiang@s.tmu.edu.tw.
authors.forename: Chang-Jung
authors.initials: CJ
authors.lastname: Chiang
mesh_terms: D000818:Animals; D065634:Cerebrospinal Fluid Leak / Q000209:etiology; D007403:Intervertebral Disc / Q000293:injuries / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000293:injuries / Q000601:surgery*; D023421:Models, Animal; D013129:Spinal Puncture / Q000009:adverse effects*; D013536:Suture Techniques; D013552:Swine
keywords: Annular repair; Failure strength; Needle puncture