title: Histologic study of periprosthetic osteolytic lesions after AES total ankle replacement. A 22 case series.
abstract: BACKGROUND
  Medium-term results for total ankle replacement (TAR) are in general satisfactory, but there is a high redo rate for periprosthetic osteolysis associated with the AES implant.
  
  
  OBJECTIVE
  Comparing radioclinical findings and histologic analysis of implant revision procedure specimens can account for the elevated rate of osteolysis associated with the AES TAR implant.
  
  
  METHODS
  In a prospective series of 84 AES TAR implants (2003-2008), 25 underwent revision for osteolysis (including three undergoing revision twice) at a mean 59.8 months. Eight patients had hydroxyapatite (HA) coated models and the others had titanium-hydroxyapatite (Ti-HA) coatings. Radiographs were systematically analyzed on Besse's protocol and evolution was monitored on AOFAS scores. The 94 specimens taken for histologic analysis during revision were re-examined, focusing specifically on foreign bodies.
  
  
  RESULTS
  Macroscopically, no metallosis or polyethylene wear was found at revision. AOFAS global and pain scores fell respectively from 89.7/100 at 1 year postoperatively to 72.9 before revision and from 32.5/40 to 20.6/40, although global scores were unchanged in 25% of patients. Radiologically, all patients showed tibial and talar osteolytic lesions, 45% showed cortical lysis and in 25% the implant had collapsed into the cysts. All specimens showed macrophagic granulomatous inflammatory reactions in contact with a foreign body; the cysts showed necrotic remodeling. Some of the foreign bodies could be identified on optical histologic examination with polyethylene in 95% of the specimens and metal in 60% (100% of HA-coated models and 33.3% of Ti-HA-coated models). Unidentifiable material was associated: a brownish pigment in Ti-HA-coated models (33.3%) and flakey bodies in 44.4% of the HA-coated models and 18.2% of the Ti-HA-coated models.
  
  
  CONCLUSIONS
  The phenomenon of periprosthetic osteolysis is still poorly understood, although implant wear debris seems to be implicated. All the patients with HA-coated implants with modular tibial stem had metal particles in the tissue around the implant, although their exact nature could not be determined. The double-layer Ti-HA coating may induce delamination by fretting while the biological bone anchorage is forming.
  
  
  METHODS
  Prospective cohort study - Level IV.
authors: Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Service de chirurgie Orthopédique et Traumatologique, 69495 Pierre-Bénite cedex, France. Electronic address: fred.dalat@hotmail.fr.
authors: F
authors: F
authors: Dalat
authors: R
authors: R
authors: Barnoud
authors: M-H
authors: MH
authors: Fessy
authors: J-L
authors: JL
authors: Besse
mesh_terms: D058737:Arthroplasty, Replacement, Ankle; D001706:Biopsy; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010014:Osteolysis / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*; D011859:Radiography; D012189:Retrospective Studies
keywords: Histology; Periprosthetic osteolysis; Total ankle arthroplasty