Laurent B Willemot1, Ross Wodicka2, Adrian Bosworth3, Alessandro Castagna4, Joseph Burns2, Olivier Verborgt5. 1. Department of Orthopedic Surgery and Traumatology, Ghent University Hospital, Ghent, Belgium. 2. Department of Orthopedic Surgery, Southern California Institute for Orthopedic Surgery, Valencia, CA, USA. 3. Department of research and development, ConMed Linvatec, Largo, FL, USA. 4. Unità di Chirurgia della Spalla 'IRCCS Instituto Clinico Humanitas' (AC, RG), Milan, Italy. 5. Department of Orthopaedic Surgery and Traumatology, AZ Monica and University Hospital of Antwerp, Antwerp, Belgium.
Abstract
BACKGROUND: Bone-grafting procedures for recurrent shoulder instability produce low recurrence rates, although they are associated with complications such as graft non-union. Inadequate screw purchase is considered to play a causative role. However, excessive screw length can endanger neurovascular structures. The present study aimed to investigate how type and length of screws influences construct rigidity in a simplified glenoid model. METHODS: Testing was performed on composite polyurethane foam models with material properties and abstract dimensions of a deficient glenoid and an bone graft. Three screw types (cannulated 3.75 mm and 3.5 mm and solid 4.5 mm) secured the graft in a bicortical-bicortical, bicortical-unicortical and unicortical-unicortical configuration. Biomechanical testing consisted of applying axial loads when measuring graft displacement. RESULTS: At 200 N, graft displacement reached 0.74 mm, 0.27 mm and 0.24 mm for the unicortical-unicortical and 0.40 mm, 0.25 mm and 0.24 mm for the unicortical-bicortical configuration of the 3.75 mm, 3.5 mm and 4.5 mm screw types. The 3.75 mm screw incurred significant displacements in the unicortical configurations compared to the bicortical-bicortical method (p < 0.001). CONCLUSIONS: The present study demonstrates that common screw types resist physiological shear loads in a bicortical configuration. However, the 3.75 mm screws incurred significant displacements at 200 N in the unicortical configurations. These findings have implications regarding hardware selection for bone-grafting procedures.
BACKGROUND: Bone-grafting procedures for recurrent shoulder instability produce low recurrence rates, although they are associated with complications such as graft non-union. Inadequate screw purchase is considered to play a causative role. However, excessive screw length can endanger neurovascular structures. The present study aimed to investigate how type and length of screws influences construct rigidity in a simplified glenoid model. METHODS: Testing was performed on composite polyurethane foam models with material properties and abstract dimensions of a deficient glenoid and an bone graft. Three screw types (cannulated 3.75 mm and 3.5 mm and solid 4.5 mm) secured the graft in a bicortical-bicortical, bicortical-unicortical and unicortical-unicortical configuration. Biomechanical testing consisted of applying axial loads when measuring graft displacement. RESULTS: At 200 N, graft displacement reached 0.74 mm, 0.27 mm and 0.24 mm for the unicortical-unicortical and 0.40 mm, 0.25 mm and 0.24 mm for the unicortical-bicortical configuration of the 3.75 mm, 3.5 mm and 4.5 mm screw types. The 3.75 mm screw incurred significant displacements in the unicortical configurations compared to the bicortical-bicortical method (p < 0.001). CONCLUSIONS: The present study demonstrates that common screw types resist physiological shear loads in a bicortical configuration. However, the 3.75 mm screws incurred significant displacements at 200 N in the unicortical configurations. These findings have implications regarding hardware selection for bone-grafting procedures.
Authors: Markus J Tingart; Maria Apreleva; Janne Lehtinen; David Zurakowski; Jon J P Warner Journal: Am J Sports Med Date: 2004-07-20 Impact factor: 6.202
Authors: Laurent B Willemot; Sarah F Eby; Andrew R Thoreson; Phillipe Debeer; Jan Victor; Kai-Nan An; Olivier Verborgt Journal: J Shoulder Elbow Surg Date: 2014-11-12 Impact factor: 3.019
Authors: Matthew T Provencher; Zachary S Aman; Christopher M LaPrade; Andrew S Bernhardson; Gilbert Moatshe; Hunter W Storaci; Jorge Chahla; Travis Lee Turnbull; Robert F LaPrade Journal: Orthop J Sports Med Date: 2018-06-14