title: A novel technique to measure in vivo uterine suspensory ligament stiffness.
abstract: OBJECTIVE
  The purpose of this study was to describe a new computer-controlled research apparatus for measuring in vivo uterine ligament force-displacement behavior and stiffness and to present pilot data for women with and without prolapse.
  
  
  METHODS
  Seventeen women with varying uterine support underwent testing in the operating room (OR) after anesthetic induction. A tripod-mounted computer-controlled linear servoactuator was used to quantify force-displacement behavior of the cervix and supporting ligaments. The servoactuator applied a caudally directed force to a tenaculum at 4 mm/sec velocity until the traction force reached 17.8 N (4 lbs). Cervix location on Pelvic Organ Prolapse Quantification system (POP-Q) in the clinic, in the OR, at rest, and with minimal force (<1.1 N); maximum force (17.8 N) was recorded. Ligament "stiffness" between minimum and maximum force was calculated.
  
  
  RESULTS
  The mean ± SD subject age was 54.5 ± 12.7 years; parity was 2.9 ± 1.1; body mass index was 29.0 ± 4.3 kg/m(2), and POP-Q point C was -3.1 ± 3.9 cm. POP-Q point C was correlated most strongly with cervix location at maximum force (r = +0.68; P = .003) and at rest (r = +0.62; P = .009). Associations between cervix location at minimum force (r = +0.46; P = .059) and ligament stiffness (r = -0.44; P = .079) were not statistically significant. Cervix location in the OR with minimal traction lay below the lowest point found on POP-Q for 13 women.
  
  
  CONCLUSIONS
  POP-Q point C was correlated strongly with cervix location at rest and at maximum traction force; however, only 19% of the variation in POP-Q point C location was explained by ligament stiffness. The cervix location in the OR at minimal traction lay below POP-Q point C value in three-fourths of the women.
authors.affiliation: Department of Obstetrics and Gynecology, University of Michigan Medical School, Ann Arbor, MI.
authors.forename: Tovia Martirosian
authors.initials: TM
authors.lastname: Smith
authors.forename: Jiajia
authors.initials: J
authors.lastname: Luo
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Hsu
authors.forename: James
authors.initials: J
authors.lastname: Ashton-Miller
authors.forename: John Oliver
authors.initials: JO
authors.lastname: Delancey
mesh_terms: D000290:Adnexa Uteri / Q000502:physiology* / Q000503:physiopathology; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008022:Ligaments / Q000502:physiology* / Q000503:physiopathology; D008875:Middle Aged; D014596:Uterine Prolapse / Q000175:diagnosis*; D014599:Uterus / Q000502:physiology* / Q000503:physiopathology
keywords: ligament stiffness; pelvic organ prolapse