title: "Top-Out" Removal of Well-Fixed Dual-Taper Femoral Stems: Surgical Technique and Radiographic Risk Factors.
abstract: Contemporary "dual-taper" modular femoral neck-stem designs have been associated with taper corrosion-related adverse local tissue reaction (ALTR) requiring revision surgery and stem removal. Extended trochanteric osteotomy is recognized as the workhorse procedure for revision hip surgery. The aim of our study is to describe our "top-out" stem removal surgical technique and identify preoperative radiographic risk factors associated with periprosthetic fractures when using this technique.
  
  
  
  This is a single-center, single-surgeon, retrospective case series. Operative and clinic records were reviewed for patients with dual-taper modular femoral neck-stem junction who underwent revision surgery for taper tribocorrosion-related ALTR.
  
  
  
  Eighty-three patients (36 men and 47 women; mean age, 61.8 ± 10.3; body mass index, 30.2 ± 8.6) were revised using the top-out technique. Significant improvements in postoperative Harris hip score (P = .004), EuroQol 5-dimension questionnaire (EQ-5D; P < .001), and EQ-5D US-adjusted scores (P < .001) were observed at 19-months follow-up. Our study reports periprosthetic fracture incidence of 14% and reoperation rate of 7%. Periprosthetic fractures were positively correlated with radiographic parameters such as overhang distance (R = 0.376; P = .002) and overhang ratio (R = 0.312; P = .01) and negatively correlated with radiographic implant medial calcar prominence (R = -0.299; P = .01).
  
  
  
  Removal of well-fixed femoral components can be challenging, and the burden of revision surgery for taper tribocorrosion-related ALTR of these femoral stems is likely to rise. A top-out technique with systematic preoperative planning with radiographs provides a viable, alternative surgical option to remove well-fixed femoral component while preserving the femoral bony envelope.
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Kwon
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Valentin
authors.initials: V
authors.lastname: Antoci
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Eric
authors.initials: E
authors.lastname: Eisemon
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Tsung-Yuan
authors.initials: TY
authors.lastname: Tsai
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Ming Han Lincoln
authors.initials: MH
authors.lastname: Liow
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D003343:Corrosion; D005260:Female; D005269:Femur / Q000601:surgery*; D005272:Femur Neck / Q000601:surgery; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods; D057068:Periprosthetic Fractures / Q000601:surgery*; D011475:Prosthesis Failure; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
keywords: adverse local tissue reaction; modular neck femoral stems; revision total hip arthroplasty; taper corrosion; top-out technique