BACKGROUND: A biomechanical cadaver study was performed to test the stability and strength of screw osteosynthesis of surgical neck fractures of the humerus. METHODS: After bone density measurement, 64 cadaver proximal humerus bones were bent to create a subcapital fracture. The fracture was then stabilized by means of screw osteosynthesis randomly assigned to subgroups of screw positioning, size of screw, and stress test (torsion/bending). RESULTS: Two screws applied laterally and parallel were 34.2% more stable than the normal arrangement. Bone density had a dominant role with regard to maximal bending and torsion force, but no significance was found with respect to additional screws through the major tuberculum or diameter of screws. CONCLUSION: Two of the smaller 4.5-mm cannulated screws should be applied parallel from the lateral direction. Only range-of-motion exercises that produce a bending stress should be considered early after surgery, avoiding axial stress.
BACKGROUND: A biomechanical cadaver study was performed to test the stability and strength of screw osteosynthesis of surgical neck fractures of the humerus. METHODS: After bone density measurement, 64 cadaver proximal humerus bones were bent to create a subcapital fracture. The fracture was then stabilized by means of screw osteosynthesis randomly assigned to subgroups of screw positioning, size of screw, and stress test (torsion/bending). RESULTS: Two screws applied laterally and parallel were 34.2% more stable than the normal arrangement. Bone density had a dominant role with regard to maximal bending and torsion force, but no significance was found with respect to additional screws through the major tuberculum or diameter of screws. CONCLUSION: Two of the smaller 4.5-mm cannulated screws should be applied parallel from the lateral direction. Only range-of-motion exercises that produce a bending stress should be considered early after surgery, avoiding axial stress.
Authors: Christian Spross; Nicola Kaestle; Emanuel Benninger; Jürgen Fornaro; Johannes Erhardt; Vilijam Zdravkovic; Bernhard Jost Journal: Clin Orthop Relat Res Date: 2015-04-25 Impact factor: 4.176
Authors: J W A M den Teuling; B S Pauwels; L Janssen; C E Wyers; H M J Janzing; J P W van den Bergh; J W Morrenhof Journal: Bone Joint Res Date: 2017-10 Impact factor: 5.853