title: The influence of patient age and bone mineral density on osteotomy fixation stability after hallux valgus surgery: A biomechanical study.
abstract: BACKGROUND
  Oblique osteotomies of the first metatarsal are common surgical treatments for moderate to severe hallux valgus deformity. Osteotomy fixation integrity is important to minimize interfragment motion and maintain correction during healing, and our clinical observations suggest that patient age and bone quality affect fixation stability and ultimately the clinical outcome. Accordingly, this study correlated these patient factors with key mechanical measures of osteotomy angulation resistance in a cadaver hallux valgus correction model.
  
  
  METHODS
  Standard Ludloff osteotomies were created in 31 fresh-frozen first metatarsals and fixed with two cannulated, dual-pitch headless screws. Each specimen underwent 1000 plantar-to-dorsal bending loads while monitoring bending stiffness and distal fragment dorsal angulation. Donor age and bone mineral density were then correlated with each mechanical measure at selected cycling increments.
  
  
  RESULTS
  We found significant positive correlation between bone mineral density and osteotomy fixation stiffness for all evaluated load cycles. Moderate negative correlation between bone density and angulation was identified, significant for load cycle 500. There was a weak, nonsignificant negative correlation between donor age and osteotomy bending stiffness, with r ranging from -0.134 to -0.243 between the first and 1000th loads. Little correlation was demonstrable between age and angulation.
  
  
  CONCLUSIONS
  Because low bone density correlates with decreased osteotomy site stiffness and increased angulation under load, patient compliance and protected weight bearing in the early postoperative phase are particularly important if bone mineral density is exceptionally low. Correspondingly, patients with especially high bone mineral density may be considered candidates for earlier weight bearing and active physical therapy.
authors.affiliation: Hospital Klinikum Wels-Grieskirchen, Department of Orthopaedic Surgery, Grieskirchner Street 42, 4600 Wels, Austria.
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Hofstaetter
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, 4709 Creekstone Drive, Durham, NC 27703, USA. Electronic address: markus.riedl@meduniwien.ac.at.
authors.forename: Markus
authors.initials: M
authors.lastname: Riedl
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, PO Box 3093, Durham, NC 27710, USA. Electronic address: r.r.glisson@duke.edu.
authors.forename: Richard R
authors.initials: RR
authors.lastname: Glisson
authors.affiliation: Hospital Klinikum Wels-Grieskirchen, Department of Orthopaedic Surgery, Grieskirchner Street 42, 4600 Wels, Austria. Electronic address: klemens.trieb@klinikum-wegr.at.
authors.forename: Klemens
authors.initials: K
authors.lastname: Trieb
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, 4709 Creekstone Drive, Durham, NC 27703, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Easley
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D002102:Cadaver; D004548:Elasticity / Q000502:physiology; D005260:Female; D006215:Hallux Valgus / Q000601:surgery*; D006801:Humans; D008297:Male; D008682:Metatarsal Bones / Q000503:physiopathology* / Q000601:surgery*; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods / Q000592:standards; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology
keywords: Bone; Density; Hallux valgus; Ludloff; Osteotomy