title: The Femoral Head Center Shifts in a Mediocaudal Direction During Aging.
abstract: Accurate reconstruction of hip joint biomechanics is the key stone in total hip arthroplasty. Although proximal femur morphology is known to vary with both age and gender, few studies investigated this in the very elderly (ie, ≥80 years). The purpose of this study was to compare basic morphological parameters describing the position of the femoral head between very elderly and middle-aged subjects.
  
  
  
  Computed tomographic scans of the femur of 90 very elderly (mean 84 years, range 80-105 years) and 58 middle-aged subjects (mean 52 years, range 20-79 years) were made. After 3-dimensional reconstruction, the neck-shaft angle, femoral neck anteversion angle, femoral head height, femoral neck length, and mediolateral offset (ML-offset) were determined.
  
  
  
  The neck-shaft angle was on average 3.6° less in elderly males (125.9° ± 5.0°) than in middle-aged males (129.5° ± 5.1°) (P < .001). The femoral neck anteversion angle was not significantly different between both age and gender groups. The femoral head height was -12.3 mm in elderly females compared to -10.5 mm (Δ 17%) in elderly males (P = .284) and even -8.0 mm (Δ 54%) in middle-aged males. The ML-offset was 10% (4.1 mm) larger in elderly compared to middle-aged males (P < .001).
  
  
  
  These findings suggest that the femoral neck and head shift in a relative varus position during aging. Femoral prostheses with increased ML-offset and a lower caput-collum-diaphyseal angle are needed to accommodate the morphology of the femur in the very elderly. Care must be taken not to lengthen the operated leg, particularly in very elderly females.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, AHORSE Research Foundation, Zuyderland Medical Center Heerlen, Heerlen, The Netherlands.
authors.forename: Tim A E J
authors.initials: TAEJ
authors.lastname: Boymans
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, AHORSE Research Foundation, Zuyderland Medical Center Heerlen, Heerlen, The Netherlands.
authors.forename: Hidde D
authors.initials: HD
authors.lastname: Veldman
authors.affiliation: Department of Orthopaedic Surgery, Institute of Orthopedic Research & Education, Baylor College of Medicine, Houston, Texas.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Noble
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, AHORSE Research Foundation, Zuyderland Medical Center Heerlen, Heerlen, The Netherlands.
authors.forename: Ide C
authors.initials: IC
authors.lastname: Heyligers
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, AHORSE Research Foundation, Zuyderland Medical Center Heerlen, Heerlen, The Netherlands.
authors.forename: Bernd
authors.initials: B
authors.lastname: Grimm
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D005269:Femur / Q000601:surgery; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: femoral head height; femur morphology; mediolateral offset; neck-shaft angle; total hip arthroplasty; very elderly