title: Pathomechanics of hallux valgus: biomechanical and immunohistochemical study.
abstract: BACKGROUND
  One factor believed to contribute to the development of hallux valgus is an abnormality in collagen structure and makeup of the medial collateral ligament (MCL) of the first metatarsophalangeal joint (MTPJ). We hypothesized that the mechanical properties of the MCL in feet with hallux valgus are significantly different from those in normal feet and that these differences may be related to alterations in the type or distribution of collagen fibers at the interface between the MCL and the bone.
  
  
  METHODS
  Seven normal fresh-frozen cadaver feet were compared to four cadaver feet that had hallux valgus deformities. The MCL mechanical properties, structure of collagen fibers, and content proportion of type I and type III collagen were determined.
  
  
  RESULTS
  The load-deformation and stress-strain curves were curvilinear with three regions: laxity, toe, and linear regions. Laxity of the MCL in feet with hallux valgus was significantly larger than that of normal feet (p = 0.022). Stiffness and tensile modulus in the toe region in feet with hallux valgus were significantly smaller than those in normal feet (p = 0.004); however, stiffness and tensile modulus in the linear region were not significantly different. The MCL collagen fibrils in the feet with hallux valgus had a more wavy distribution than the fibrils in the normal feet.
  
  
  CONCLUSIONS
  In general, strong staining for collagen III and to a lesser extent, collagen I was observed at the interface between the MCL and bone in the feet with hallux valgus but not in the normal feet. These results indicate that the abnormal mechanical properties of the MCL in feet with hallux valgus may be related to differences in the organization of collagen I and collagen III fibrils.
authors.affiliation: Orthopaedic Surgery, Sapporo Medical University, Sapporo, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Uchiyama
authors.forename: Harold B
authors.initials: HB
authors.lastname: Kitaoka
authors.forename: Zong-Ping
authors.initials: ZP
authors.lastname: Luo
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Grande
authors.forename: Hideji
authors.initials: H
authors.lastname: Kura
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001696:Biomechanical Phenomena; D002102:Cadaver; D024042:Collagen Type I / Q000378:metabolism; D024061:Collagen Type III / Q000378:metabolism; D017885:Collateral Ligaments / Q000378:metabolism*; D005260:Female; D006215:Hallux Valgus / Q000378:metabolism* / Q000503:physiopathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011817:Rabbits
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III