title: Locking plate fixation with and without inferomedial screws for proximal humeral fractures: a biomechanical study.
abstract: PURPOSE. To compare the efficacy of locking plate fixation with and without inferomedial screws in maintaining the reduction of a proximal humeral fracture. METHODS. 22 synthetic humerus models were used. A standardised 3-part proximal humeral fracture with a 4-mm wedge segment was created and fixed with a locking plate and screws with (n=11) and without (n=11) inferomedial screws. The intrafragmentary motion of the construct at 250, 500, 750, and 1000 cycles of 532 N loading, and the load to failure of the 2 groups were compared. RESULTS. Locking plate fixation with inferomedial screws reduced the mean intrafragmentary motion in all cycles (p<0.01) and increased the load to failure (1452 N vs. 1159 N, p<0.001), compared to fixation without inferomedial screws. CONCLUSION. Additional inferomedial screws provide medial column support for fracture healing. This may reduce intrafragmentary motion and thus implant complications resulting from varus malalignment such as screw perforation or loss of reduction.
authors.affiliation: Department of Orthopaedic Research, Royal College of Surgeons, Dublin, Ireland.
authors.forename: Neil G
authors.initials: NG
authors.lastname: Burke
authors.affiliation: Department of Orthopaedic Research, Royal College of Surgeons, Dublin, Ireland.
authors.forename: Jim
authors.initials: J
authors.lastname: Kennedy
authors.affiliation: HRB Centre for Primary Care Research, Royal College of Surgeons in Ireland.
authors.forename: Grainne
authors.initials: G
authors.lastname: Cousins
authors.affiliation: School of Electrical and Mechanical Engineering, University College Dublin, Ireland.
authors.forename: David
authors.initials: D
authors.lastname: Fitzpatrick
authors.affiliation: Department of Orthopaedic Research, Royal College of Surgeons, Dublin, Ireland.
authors.forename: Hannan
authors.initials: H
authors.lastname: Mullett
mesh_terms: D001860:Bone Plates; D001863:Bone Screws; D019245:Compressive Strength; D019544:Equipment Failure Analysis; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008954:Models, Biological; D012784:Shoulder Fractures / Q000601:surgery*; D016474:Weight-Bearing
keywords: bone plates; bone screws; shoulder fracture