title: Retroacetabular osteolytic lesions behind well-fixed prosthetic cups: pilot study of bearings-retaining surgery.
abstract: BACKGROUND
  Osteolytic lesions are common radiological findings behind acetabular prosthetic cups. If the cup is well-fixed, the management is quite controversial. Although implant exchange is the most reliable procedure, in most cases it could be considered overtreatment, with the potential for further morbidity and bone loss. Liner exchange associated with lesion debridement and grafting represents an alternative option that is less invasive. Here we present our experiences from a small pilot study of minimally invasive osteolysis treatment without bearings exchange in patients with no evidence of liner wear.
  
  
  METHODS
  
  
  
  METHODS
  retroacetabular osteolytic lesions in ceramic-on-polyethylene or metal-on-polyethylene cementless total hip arthroplasties, affecting more than 50% of the bone-prosthesis interface on anteroposterior radiography.
  
  
  METHODS
  head penetration into the liner, suspected loosening or infection. Six patients were selected, two asymptomatic and four symptomatic. Only the symptomatic patients accepted the proposed treatment (performed between June 2004 and March 2006). All of them received fluoroscopy-assisted lesion debridement through an iliac cortical window, morcellized bone allograft mixed with autologous platelet-rich plasma, joint exploration for culture and lavage through a small capsular window. Patients were followed up clinically and radiologically at six months, 12 months, and then yearly.
  
  
  RESULTS
  Three patients out of four showed clinical and radiological improvement. One showed radiological improvement only, and recently underwent cup exchange for subsequent loosening. The visual analog scale (VAS) values for pain decreased on average, but not significantly. No major complications occurred. No recurrence was noted at 2.25-4 years' follow-up.
  
  
  CONCLUSIONS
  Although the small series does not allow any absolute conclusions to be drawn, the reported results seem to justify further, wider studies. It is still unclear if osteolytic lesions associated with no wear of the poly liner would progress to implant failure if left untreated. Until the problem is better understood, this procedure might represent an interesting way to prevent potential loosening and severe bone loss in intact sockets.
authors.affiliation: III Division of Orthopaedics and Trauma, Gaetano Pini Orthopaedic Institute, Piazza C. Ferrari, 1, 20122 Milan, Italy. lmcpierannunzii@hotmail.com
authors.forename: Luca
authors.initials: L
authors.lastname: Pierannunzii
authors.forename: Florian
authors.initials: F
authors.lastname: Fischer
authors.forename: Marco
authors.initials: M
authors.lastname: d'Imporzano