title: Conversion of arthrodesis to total hip arthroplasty: clinical outcome, complications, and prognostic factors of 21 consecutive cases.
abstract: BACKGROUND
  Although the results of hip arthrodesis compare favorably with those of total hip arthroplasty (THA) in younger patients, long-term consequences such as osteoarthritis of the neighboring joints may necessitate conversion of the arthrodesis to THA.
  
  
  OBJECTIVE
  The purpose of the present study is to assess mid-term clinical outcome and self-perceived improvement in patients who underwent conversion at our department. Secondary aims were incidence of complications and association between patient characteristics and characteristics of the fusions with the outcome of the procedure.
  
  
  METHODS
  The study sample comprised 21 cases in 20 patients. Minimum follow-up was 3 years (mean, 8 ± 6.5 years) in 20 cases. Thirteen patients had surgical hip fusions and 7 (8 hips) had nonsurgical fusions. Mean age at the time of conversion was 58.5 years.
  
  
  RESULTS
  Nineteen out of 21 cases had functioning implants at the latest follow-up visit. According to the Merle d'Aubigné scale, outcome was considered excellent, very good, or good in 15 cases. Lower back pain was reduced in all patients. All but two patients were satisfied after the conversion. The main complications observed included incomplete removal of bone block, intra-operative fractures, dislocation and damage to the femoral artery. Time to conversion and type of fusion had no significant correlation with the clinical outcome.
  
  
  CONCLUSIONS
  Conversion THA is a challenging but successful procedure according to the mid-term clinical outcome observed. Our study suggests that, prognostic factors should be used with caution when establishing indications and post-surgical expectations.
authors.affiliation: Hospital General Universitario Gregorio Marañón, C/Doctor Esquerdo 46, 28007 Madrid, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Villanueva
authors.affiliation: Hospital General Universitario Gregorio Marañón, C/Doctor Esquerdo 46, 28007 Madrid, Spain.
authors.forename: Francisco Borja
authors.initials: FB
authors.lastname: Sobrón
authors.affiliation: Hospital General Universitario Gregorio Marañón, C/Doctor Esquerdo 46, 28007 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Parra
authors.affiliation: Hospital General Universitario Gregorio Marañón, C/Doctor Esquerdo 46, 28007 Madrid, Spain.
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Rojo
authors.affiliation: Hospital General Universitario Gregorio Marañón, C/Doctor Esquerdo 46, 28007 Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Chana
authors.affiliation: Hospital General Universitario Gregorio Marañón, C/Doctor Esquerdo 46, 28007 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Vaquero
keywords: conversion; hip arthrodesis; total hip arthroplasty