title: Polyaxial locking and compression screws improve construct stiffness of acetabular cup fixation: a biomechanical study.
abstract: Bone ingrowth into uncemented acetabular components requires intimate cup-bone contact and rigid fixation, which can be difficult to achieve in revision hip arthroplasty. This study compares polyaxial compression locking screws with non-locked and cancellous screw constructs for acetabular cup fixation. An acetabular cup modified with screw holes to provide both compression and angular stability was implanted into a bone substitute. Coronal lever out, axial torsion and push-out tests were performed with an Instron testing machine, measuring load versus displacement. Polyaxial locking compression screws significantly improved construct stiffness compared with non-locked or cancellous screws. This increased construct stiffness will likely reduce interfacial micromotion. Further research is required to determine whether this will improve bone ingrowth in vivo and reduce cup failure.
authors.affiliation: Department of Orthopaedic Surgery, Royal Perth Hospital, Perth, Western Australia, Australia.
authors.forename: Lachlan P
authors.initials: LP
authors.lastname: Milne
authors.affiliation: Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia, Australia.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Kop
authors.affiliation: Department of Orthopaedic Surgery, Royal Perth Hospital, Perth, Western Australia, Australia.
authors.forename: Markus S
authors.initials: MS
authors.lastname: Kuster
mesh_terms: D000077:Acetabulum / Q000503:physiopathology / Q000601:surgery*; D019644:Arthroplasty, Replacement, Hip; D001696:Biomechanical Phenomena; D001863:Bone Screws; D018786:Bone Substitutes; D006622:Hip Prosthesis; D016348:Osseointegration; D011474:Prosthesis Design
chemical_list: D018786:Bone Substitutes
keywords: acetabulum; biomechanics; hip prosthesis; prosthesis design; revision hip arthroplasty