title: Stem modularity alone is not effective in reducing dislocation rate in hip revision surgery.
abstract: BACKGROUND
  Dislocation is a serious complication following total hip arthroplasty (THA). Femoral revision using monoblock components has been associated with high incidence of subsidence and dislocation. Advantages of modular stems in THA have long been debated. The aim of this retrospective study is to assess the capability of an uncemented modular stem in decreasing the incidence of early dislocation subsequent to revision THA.
  
  
  METHODS
  We evaluated the dislocation rate during the first 2 years following revision surgery in two groups of patients who were treated by implantation of a cementless tapered femoral prosthesis; a standard-modularity stem (Wagner SL) and an increased-modularity stem (Profemur R) were used, respectively, in 66 hips (group I, 64 patients) and 102 hips (group II, 97 patients). Group I consisted of 47 females and 17 males with average age of 66 years (range 29-84 years). Group II included 60 females and 37 males with average age of 70 years (range 48-89 years).
  
  
  RESULTS
  Dislocation occurred in six hips (9.1%) of group I and in seven hips (6.8%) of group II (P = 0.401). Dislocations were observed early in both groups, except one hip in group II that dislocated 434 days postoperatively and required surgical reduction. All other dislocations were treated by closed reduction. No recurrence was observed.
  
  
  CONCLUSIONS
  The use of an increased-modularity revision stem alone did not prove to be effective in reducing the risk of postoperative dislocation.
authors.affiliation: Department of Orthopaedic Surgery, University School of Medicine, Verona, Italy. regisdario@siot.it
authors.forename: Dario
authors.initials: D
authors.lastname: Regis
authors.forename: Andrea
authors.initials: A
authors.lastname: Sandri
authors.forename: Pietro
authors.initials: P
authors.lastname: Bartolozzi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000706:statistics & numerical data; D005260:Female; D006617:Hip Dislocation / Q000453:epidemiology / Q000517:prevention & control* / Q000601:surgery; D006622:Hip Prosthesis / Q000009:adverse effects / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure; D012086:Reoperation / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors