title: A tissue engineering strategy for the treatment of avascular necrosis of the femoral head.
abstract: OBJECTIVE
  Skeletal stem cells (SSCs) and impaction bone grafting (IBG) can be combined to produce a mechanically stable living bone composite. This novel strategy has been translated to the treatment of avascular necrosis of the femoral head. Surgical technique, clinical follow-up and retrieval analysis data of this translational case series is presented.
  
  
  METHODS
  SSCs and milled allograft were impacted into necrotic bone in five femoral heads of four patients. Cell viability was confirmed by parallel in vitro culture of the cell-graft constructs. Patient follow-up was by serial clinical and radiological examination. Tissue engineered bone was retrieved from two retrieved femoral heads and was analysed by histology, microcomputed tomography (μCT) and mechanical testing.
  
  
  RESULTS
  Three patients remain asymptomatic at 22- to 44-month follow-up. One patient (both hips) required total hip replacement due to widespread residual necrosis. Retrieved tissue engineered bone demonstrated a mature trabecular micro-architecture histologically and on μCT. Bone density and axial compression strength were comparable to trabecular bone.
  
  
  CONCLUSIONS
  Clinical follow-up shows this to be an effective new treatment for focal early stage avascular necrosis of the femoral head. Unique retrieval analysis of clinically translated tissue engineered bone has demonstrated regeneration of tissue that is both structurally and functionally analogous to normal trabecular bone.
authors.affiliation: Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Institute of Developmental Sciences, Tremona Road, Southampton SO16 6YD, UK. Electronic address: alexaarvold@doctors.org.uk.
authors.forename: A
authors.initials: A
authors.lastname: Aarvold
authors.forename: J O
authors.initials: JO
authors.lastname: Smith
authors.forename: E R
authors.initials: ER
authors.lastname: Tayton
authors.forename: A M H
authors.initials: AM
authors.lastname: Jones
authors.forename: J I
authors.initials: JI
authors.lastname: Dawson
authors.forename: S
authors.initials: S
authors.lastname: Lanham
authors.forename: A
authors.initials: A
authors.lastname: Briscoe
authors.forename: D G
authors.initials: DG
authors.lastname: Dunlop
authors.forename: R O C
authors.initials: RO
authors.lastname: Oreffo
mesh_terms: D000328:Adult; D064591:Allografts; D016025:Bone Transplantation / Q000379:methods*; D005260:Female; D005271:Femur Head Necrosis / Q000601:surgery*; D006801:Humans; D008297:Male; D017410:Practice Guidelines as Topic; D033581:Stem Cell Transplantation / Q000379:methods*; D023822:Tissue Engineering / Q000592:standards*; D016896:Treatment Outcome
keywords: Avascular necrosis; Femoral head; Impaction bone grafting; Skeletal stem cells; Translation
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