title: Ultrastructure and innervation of thumb carpometacarpal ligaments in surgical patients with osteoarthritis.
abstract: BACKGROUND
  The complex configuration of the thumb carpometacarpal (CMC-1) joint relies on musculotendinous and ligamentous support for precise circumduction. Ligament innervation contributes to joint stability and proprioception. Evidence suggests abnormal ligament innervation is associated with osteoarthritis (OA) in large joints; however, little is known about CMC-1 ligament innervation characteristics in patients with OA. We studied the dorsal radial ligament (DRL) and the anterior oblique ligament (AOL), ligaments with a reported divergent presence of mechanoreceptors in nonosteoarthritic joints.
  
  
  OBJECTIVE
  This study's purposes were (1) to examine the ultrastructural architecture of CMC-1 ligaments in surgical patients with OA; (2) to describe innervation, specifically looking at mechanoreceptors, of these ligaments using immunohistochemical techniques and compare the AOL and DRL in terms of innervation; and (3) to determine whether there is a correlation between age and mechanoreceptor density.
  
  
  METHODS
  The AOL and DRL were harvested from 11 patients with OA during trapeziectomy (10 women, one man; mean age, 67 years). The 22 ligaments were sectioned in paraffin and analyzed using immunoflourescent triple staining microscopy.
  
  
  RESULTS
  In contrast to the organized collagen bundles of the DRL, the AOL appeared to be composed of disorganized connective tissue with few collagen fibers and little innervation. Mechanoreceptors were identified in CMC-1 ligaments of all patients with OA. The DRL was significantly more innervated than the AOL. There was no significant correlation between innervation of the DRL and AOL and patient age.
  
  
  CONCLUSIONS
  The dense collagen structure and rich innervation of the DRL in patients with OA suggest that the DRL has an important proprioceptive and stabilizing role.
  
  
  CONCLUSIONS
  Ligament innervation may correlate with proprioceptive and neuromuscular changes in OA pathophysiology and consequently support further investigation of innervation in disease prevention and treatment strategies.
authors.affiliation: Department of Clinical Science and Education, Karolinska Institute, Sjukhusbacken 10, 118 83, Stockholm, Sweden, nathalie.mobargha@ki.se.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mobargha
authors.forename: Cassie
authors.initials: C
authors.lastname: Ludwig
authors.forename: Amy L
authors.initials: AL
authors.lastname: Ladd
authors.forename: Elisabet
authors.initials: E
authors.lastname: Hagert
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D001696:Biomechanical Phenomena; D052737:Carpometacarpal Joints / Q000737:chemistry / Q000294:innervation* / Q000601:surgery / Q000648:ultrastructure*; D003094:Collagen / Q000032:analysis; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008022:Ligaments / Q000737:chemistry / Q000294:innervation* / Q000601:surgery / Q000648:ultrastructure*; D008297:Male; D008465:Mechanoreceptors / Q000737:chemistry / Q000648:ultrastructure; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000032:analysis; D010003:Osteoarthritis / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D010027:Osteotomy; D017475:Receptors, Nerve Growth Factor / Q000032:analysis; D013933:Thumb / Q000294:innervation*; D043222:Ubiquitin Thiolesterase / Q000032:analysis
chemical_list: D015415:Biomarkers; C484065:NGFR protein, human; D009419:Nerve Tissue Proteins; D017475:Receptors, Nerve Growth Factor; C482860:UCHL1 protein, human; D003094:Collagen; D043222:Ubiquitin Thiolesterase