title: Refixation of osteochondral fractures by ultrasound-activated, resorbable pins: An ovine in vivo study.
abstract: OBJECTIVE
  Osteochondral injuries, if not treated adequately, often lead to severe osteoarthritis. Possible treatment options include refixation of the fragment or replacement therapies such as Pridie drilling, microfracture or osteochondral grafts, all of which have certain disadvantages. Only refixation of the fragment can produce a smooth and resilient joint surface. The aim of this study was the evaluation of an ultrasound-activated bioresorbable pin for the refixation of osteochondral fragments under physiological conditions.
  
  
  METHODS
  In 16 Merino sheep, specific osteochondral fragments of the medial femoral condyle were produced and refixed with one of conventional bioresorbable pins, titanium screws or ultrasound-activated pins. Macro- and microscopic scoring was undertaken after three months.
  
  
  RESULTS
  The healing ratio with ultrasound-activated pins was higher than with conventional pins. No negative heat effect on cartilage has been shown.
  
  
  CONCLUSIONS
  As the material is bioresorbable, no further surgery is required to remove the implant. MRI imaging is not compromised, as it is with implanted screws. The use of bioresorbable pins using ultrasound is a promising technology for the refixation of osteochondral fractures.
authors.affiliation: Berufsgenossenschaftliches Unfallkrankenhaus Hamburg, Department of Traumatology, Orthopaedics and Sports Medicine, Bergedorfer Straße 10, 21033 Hamburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Neumann
authors.forename: A P
authors.initials: AP
authors.lastname: Schulz
authors.forename: J
authors.initials: J
authors.lastname: Gille
authors.forename: M
authors.initials: M
authors.lastname: Klinger
authors.forename: C
authors.initials: C
authors.lastname: Jürgens
authors.forename: N
authors.initials: N
authors.lastname: Reimers
authors.forename: B
authors.initials: B
authors.lastname: Kienast
keywords: Bioresorbable implant; Cartilage; Osteochondral fracture; Polylactide; Sheep study; Ultrasound-activated pin