title: Alterations in femoral strain, micromotion, cortical geometry, cortical porosity, and bony ingrowth in uncemented collared and collarless prostheses in the dog.
abstract: The effects of a collared femoral endoprosthesis in uncemented total hip arthroplasty were evaluated in 12 dogs. This experimental study compared the biomechanic and histologic responses between collared and collarless femoral prostheses 4 months after implantation. Implant stability (micromotion) and cortical surface strain were evaluated immediately and 4 months after implantation in a simulated postoperative condition, whereas bone ingrowth, cortical porosity, and cortical remodeling were assessed after 4 months only. There were no significant differences in implant stability or cortical surface strains when the collared and collarless groups were compared acutely or after 4 months (P > .05). There were also no significant differences in percent fill, bony ingrowth, or cortical geometry after 4 months (P > .05). There was a significant increase in cortical porosity measured from the proximal femur after 4 months for both the collared (P = .0002) and collarless groups (P = .009) and when both groups were compared (collarless, 8.2% and collared, 5.8%; P = .03). The results suggest that a collar may be beneficial in decreasing the cortical remodeling that occurs in the proximal femoral cortex after implantation of an uncemented total hip arthroplasty.
authors.affiliation: Comparative Orthopaedic Research Laboratory, School of Veterinary Medicine, University of Wisconsin-Madison 53706, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Manley
authors.forename: R
authors.initials: R
authors.lastname: Vanderby
authors.forename: S
authors.initials: S
authors.lastname: Kohles
authors.forename: M D
authors.initials: MD
authors.lastname: Markel
authors.forename: J P
authors.initials: JP
authors.lastname: Heiner
mesh_terms: D000818:Animals; D016723:Bone Remodeling / Q000502:physiology; D004285:Dogs; D005269:Femur / Q000000981:diagnostic imaging / Q000503:physiopathology; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D006622:Hip Prosthesis; D016348:Osseointegration / Q000502:physiology*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D013314:Stress, Mechanical; D013997:Time Factors; D016474:Weight-Bearing / Q000502:physiology