title: Correlation of computed tomography with histology in the assessment of periprosthetic defect healing.
abstract: Computed tomography (CT) may more accurately assess the healing of grafted osteolytic lesions around acetabular components compared with plain radiographs, although clinical validation is lacking. To determine whether clinical or micro-CT imaging could assess accurately the grafted lesion compared with histology, we therefore quantified bone healing and ingrowth to determine an effective rhBMP-2 dose and ratio to allograft bone when grafted adjacent to a cementless porous-coated component. We grafted surgically created acetabular defects in canines (n = 20) before uncemented total hip arthroplasty. At 6 weeks, embedded acetabula were imaged and the CT slice images matched to histology section images. The percentage of bone in the defect and growth into the porous surface was assessed quantitatively. Low-dose rhBMP-2 with allograft (1:5 ratio) resulted in a higher percentage of defect healing (43.8%) than rhBMP-2 alone (29.2%) and a higher percentage of bone ingrowth (15.7%) than allograft bone alone (1.1%) as measured by histology. Micro-CT measurements were similar to histologic measurements of defect healing, whereas clinical CT overestimated periprosthetic bone by 38%. Neither clinical CT nor micro-CT techniques are adequate for assessing ingrowth or the bone-implant interface with metal artifacts.
authors.affiliation: Fellowship of Orthopaedic Researchers, Metairie, LA, USA.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Cook
authors.forename: Laura P
authors.initials: LP
authors.lastname: Patron
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Salkeld
authors.forename: Kirk E
authors.initials: KE
authors.lastname: Smith
authors.forename: Bruce
authors.initials: B
authors.lastname: Whiting
authors.forename: Robert L
authors.initials: RL
authors.lastname: Barrack
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000503:physiopathology / Q000601:surgery*; D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D016477:Artifacts; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage*; D016025:Bone Transplantation; D020099:Coated Materials, Biocompatible; D004285:Dogs; D006622:Hip Prosthesis; D023421:Models, Animal; D016348:Osseointegration / Q000187:drug effects*; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D011994:Recombinant Proteins / Q000008:administration & dosage; D015203:Reproducibility of Results; D015503:Surgical Sponges; D013997:Time Factors; D014025:Titanium; D014057:Tomography, X-Ray Computed; D014184:Transplantation, Homologous; D055114:X-Ray Microtomography
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D020099:Coated Materials, Biocompatible; D011994:Recombinant Proteins; D014025:Titanium