title: An ultrasound-guided, tendon-sparing, lateral approach to injection of the navicular bursa.
abstract: BACKGROUND
  Navicular disease in the horse often requires injection of the navicular bursa. We have developed an ultrasound-guided, lateral needle approach to navicular bursocentesis, which avoids penetration of the deep digital flexor tendon (DDFT) and the need for radiographic control.
  
  
  OBJECTIVE
  To describe and evaluate the feasibility and efficacy of an ultrasound-guided, lateral bursocentesis technique.
  
  
  METHODS
  Cadaveric and in vivo experiments.
  
  
  METHODS
  The navicular bursa in 62 cadaveric forelimbs of 31 horses and in both forelimbs of 26 live horses, positioned with the foot flexed in a navicular block, were submitted to lateral, ultrasound-guided injection of 1.5 ml radiocontrast agent. Lateromedial radiographs were taken to locate the contrast. A second injection of 0.5 ml methylene blue was administered during needle withdrawal in cadaveric limbs to investigate the needle pathway during dissection.
  
  
  RESULTS
  Contrast agent was successfully deposited in the navicular bursa in 104 of 114 (91%) limbs and in the navicular bursa alone in 89 of 114 (78%) limbs. Dissection showed no evidence of penetration of the DDFT in cadaver limbs. Failure to inject the navicular bursa was significantly associated with poor quality of the ultrasound image (P = 0.04) and resulted in aberrant injection of the distal interphalangeal joint in five of 114 (4%) limbs, the peribursal soft tissues in four of 114 (4%) limbs and the digital flexor tendon sheath in one of 114 (0.9%) limbs. Synovial fluid was observed at the needle hub in 58% of live horses.
  
  
  CONCLUSIONS
  It is unknown whether injection results obtained in the limbs of horses without disease can be extrapolated to horses with clinical disease of the podotrochlear apparatus. The localisation of contrast medium on radiographs may not accurately reflect the behaviour of local anaesthetic solution or therapeutic medications injected in the navicular bursa.
  
  
  CONCLUSIONS
  This lateral, ultrasound-guided technique for injecting the navicular bursa is effective, does not penetrate the DDFT and avoids exposure of personnel to radiation.
authors.affiliation: Pole Equin, VetAgro Sup, Marcy L'Étoile, France.
authors.forename: K
authors.initials: K
authors.lastname: Nottrott
authors.affiliation: Pole Equin, VetAgro Sup, Marcy L'Étoile, France.
authors.forename: C
authors.initials: C
authors.lastname: De Guio
authors.affiliation: Pole Equin, VetAgro Sup, Marcy L'Étoile, France.
authors.forename: A
authors.initials: A
authors.lastname: Khairoun
authors.affiliation: Pole Equin, VetAgro Sup, Marcy L'Étoile, France.
authors.forename: M
authors.initials: M
authors.lastname: Schramme
mesh_terms: D000818:Animals; D002061:Bursa, Synovial / Q000000981:diagnostic imaging*; D002102:Cadaver; D005552:Forelimb; D006734:Horse Diseases / Q000000981:diagnostic imaging*; D006736:Horses; D007267:Injections / Q000379:methods / Q000662:veterinary*; D013639:Tarsal Bones; D013710:Tendons / Q000033:anatomy & histology*
keywords: bursocentesis; foot; horse; navicular bursa; ultrasound