title: Contribution of the Pubofemoral Ligament to Hip Stability: A Biomechanical Study.
abstract: OBJECTIVE
  To determine the isolated function of the pubofemoral ligament of the hip capsule and its contribution to hip stability in external/internal rotational motion during flexion greater than 30° and abduction.
  
  
  METHODS
  Thirteen hips from 7 fresh-frozen pelvis-to-toe cadavers were skeletonized from the lumbar spine to the distal femur with the capsular ligaments intact. Computed tomographic imaging was performed to ensure no occult pathological state existed, and assess bony anatomy. Specimens were placed on a surgical table in supine position with lower extremities resting on a custom-designed polyvinylchloride frame. Hip internal and external rotation was measured with the hip placed into a combination of the following motions: 30°, 60°, 110° hip flexion and 0°, 20°, 40° abduction. Testing positions were randomized. The pubofemoral ligament was released and measurements were repeated, followed by releasing the ligamentum teres.
  
  
  RESULTS
  Analysis of the 2,106 measurements recorded demonstrates the pubofemoral ligament as a main controller of hip internal rotation during hip flexion beyond 30° and abduction. Hip internal rotation was increased up to 438.9% (P < .001) when the pubofemoral ligament was released and 412.9% (P < .001) when both the pubofemoral and teres ligament were released, compared with the native state.
  
  
  CONCLUSIONS
  The hypothesis of the pubofemoral ligament as one of the contributing factors of anterior inferior hip stability by controlling external rotation of the hip in flexion beyond 30° and abduction was disproved. The pubofemoral ligament maintains a key function in limiting internal rotation in the position of increasing hip flexion beyond 30° and abduction. This cadaveric study concludes previous attempts at understanding the anatomical and biomechanical function of the capsular ligaments and their role in hip stability.
  
  
  CONCLUSIONS
  The present study contributes to the understanding of hip stability and biomechanical function of the pubofemoral ligament.
authors.affiliation: Hip Preservation Center, Baylor Scott & White Health, Dallas, Texas, U.S.A.. Electronic address: haldavidmartin@yahoo.com.
authors.forename: Hal D
authors.initials: HD
authors.lastname: Martin
authors.affiliation: Hip Preservation Center, Baylor Scott & White Health, Dallas, Texas, U.S.A.; Bioengineering Department, University of Texas at Arlington, Engineering Research Building, Arlington, Texas, U.S.A.
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Khoury
authors.affiliation: Hip Preservation Center, Baylor Scott & White Health, Dallas, Texas, U.S.A.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Schröder
authors.affiliation: Hip Preservation Center, Baylor Scott & White Health, Dallas, Texas, U.S.A.; College of Medicine, University of Oklahoma, Oklahoma City, Oklahoma, U.S.A.
authors.forename: Eric
authors.initials: E
authors.lastname: Johnson
authors.affiliation: Hip Preservation Center, Baylor Scott & White Health, Dallas, Texas, U.S.A.
authors.forename: Juan
authors.initials: J
authors.lastname: Gómez-Hoyos
authors.affiliation: Hip Preservation Center, Baylor Scott & White Health, Dallas, Texas, U.S.A.
authors.forename: Salvador
authors.initials: S
authors.lastname: Campos
authors.affiliation: Hip Preservation Center, Baylor Scott & White Health, Dallas, Texas, U.S.A.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Palmer
mesh_terms: D001696:Biomechanical Phenomena; D002102:Cadaver; D005269:Femur / Q000033:anatomy & histology; D006621:Hip Joint / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008023:Ligaments, Articular / Q000033:anatomy & histology / Q000502:physiology*; D011630:Pubic Bone / Q000033:anatomy & histology; D016059:Range of Motion, Articular