title: Anatomic and histologic features and ultrasonographic appearance of the collateral ligaments of the metacarpophalangeal and metatarsophalangeal joints in cadaveric limbs from horses without lameness.
abstract: OBJECTIVE
  To describe the anatomic and histologic features of the collateral ligaments (CLs) of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in cadaveric limbs obtained from nonlame horses and to compare the histologic findings with the ultrasonographic appearance of the CLs.
  
  
  METHODS
  Medial and lateral CLs of the MCP and MTP joints of 28 limbs (16 forelimbs and 12 hind limbs) from 9 adult nonlame horses euthanized for reasons unrelated to the study.
  
  
  METHODS
  26 limbs of 8 horses were examined by ultrasonography immediately after euthanasia. Postmortem gross and histologic examinations were performed for all 28 limbs. Histologic and ultrasonographic images were graded and compared.
  
  
  RESULTS
  Ultrasonographically, the mean ± SD depth and width of the superficial CL were 5.1 ± 0.7 mm and 20.5 ± 1.7 mm, respectively. On histologic examination, only 125 of 319 (39%) specimens obtained from 56 medial and lateral CLs appeared normal. Histopathologic findings varied from mild changes in cellular density and collagen fiber orientation to severe fibrocartilaginous metaplasia. The degree of CL lesion severity increased distally, and the lateral CL was affected more frequently than was the medial CL. Ultrasonographically detectable abnormalities were not correlated with the histologic findings.
  
  
  CONCLUSIONS
  In horses, histologic abnormalities within the CLs of the MCP and MTP joints may be an adaptive response to joint hyperextension and compression and might predispose horses to desmopathy and ligament failure in the event of trauma. Ultrasonography did not detect morphologic changes of the CL matrix. For an accurate diagnosis of subclinical lesions, more sensitive imaging techniques (eg, MRI) should be considered.
authors.affiliation: Institute of Anatomy, Histology & Embryology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
authors.forename: Friederike
authors.initials: F
authors.lastname: Pohlin
authors.forename: Johannes
authors.initials: J
authors.lastname: Edinger
authors.forename: Florien
authors.initials: F
authors.lastname: Jenner
authors.forename: Monika
authors.initials: M
authors.lastname: Egerbacher
mesh_terms: D000818:Animals; D002102:Cadaver; D017885:Collateral Ligaments / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005552:Forelimb; D006614:Hindlimb; D006736:Horses / Q000033:anatomy & histology*; D008662:Metacarpophalangeal Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008683:Metatarsophalangeal Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011859:Radiography; D014463:Ultrasonography