title: Influence of patient-related characteristics on early migration in calcar-guided short-stem total hip arthroplasty: a 2-year migration analysis using EBRA-FCA.
abstract: BACKGROUND
  Short stems have gained popularity in recent years. Because of encouraging clinical results, indications have been expended from young to elderly and obese patients. However, long-term results are lacking. The purpose of this study was to evaluate the influence of gender, age, body weight, body mass index (BMI), and offset version on short-stem migration in correlation to the clinical outcome.
  
  
  METHODS
  The implant migration of 202 metaphyseal-anchoring, calcar-guided short stems in 151 patients was assessed by "Einzel-Bild-Roentgen-Analyse" femoral component analysis (EBRA-FCA, femoral component analysis) in a 2-year follow-up. Full weight bearing was allowed directly after surgery. Patients were divided into groups regarding gender, age, body weight, BMI, and offset version. The Harris hip score (HHS) and satisfaction on visual analogue scale (VAS) were analyzed.
  
  
  RESULTS
  After 2 years, mean axial subsidence of all 202 implants was 1.43 mm (standard deviation, SD 1.45 mm). A continuous reduction of initially pronounced subsidence over time could be observed. None of the stems had to be revised. Statistically significant increased rates of subsidence were seen in male (1.68 mm; SD 1.56 mm; p = 0.005) and heavy patients (1.54 mm; SD 1.48 mm; p = 0.022). No differences in implant migration were found regarding age, BMI, and different offset versions. HHS improved markedly from 45.8 (SD 15.9) to 98.1 (SD 4.7) while satisfaction on VAS improved from 1.8 (SD 2.2) to 9.7 (SD 0.9) after 2 years.
  
  
  CONCLUSIONS
  The results suggest a migration pattern with initially pronounced subsidence followed by subsequent stabilization. Male and obese patients show a slightly increased initial subsidence without any signs of sustained micromovement. No correlation was found concerning clinical results and pronounced initial subsidence above the threshold of 1.5 mm. No aseptic loosening or other signs of implant failure were seen within the observation period of 2 years.
  
  
  BACKGROUND
  German Clinical Trials Register, DRKS00009834.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, St. Josefs Hospital Wiesbaden, Beethovenstr. 20, 65189, Wiesbaden, Germany. kkutzner@joho.de.
authors.forename: Karl Philipp
authors.initials: KP
authors.lastname: Kutzner
authors.affiliation: Clinic of Traumatology, Hand- and Orthopaedic Surgery, HELIOS Dr. Horst Schmidt Clinic Wiesbaden, Ludwig-Erhard-Str. 100, 65199, Wiesbaden, Germany. mark.kovacevic@gmx.de.
authors.forename: Mark Predrag
authors.initials: MP
authors.lastname: Kovacevic
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany. Tobias.Freitag@rku.de.
authors.forename: Tobias
authors.initials: T
authors.lastname: Freitag
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany. dea.fuchs@me.com.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fuchs
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany. Heiko.Reichel@rku.de.
authors.forename: Heiko
authors.initials: H
authors.lastname: Reichel
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany. Ralf.Bieger@rku.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Bieger
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors