SLR - November 2009 - Benjamin W. Carelock
Reference:
Bottlang, M., Doornink, J., Fitzpatrick, D.C., Madey, S.M. (2009). Far cortical locking can reduce stiffness of locked plating constructs while retaining construct strength. Journal of Bone & Joint Surgery (American), 91, 1985-1994.
Scientific Literature Reviews
Reviewed By: Benjamin W. Carelock, DPM
Residency Program: Yale/VACT
Podiatric Relevance:
While locking plate fixation has promised improved strength in the setting of poor bone stock or comminution, the increased rigidity created by locking constructs has been shown to have a det-rimental effect on secondary bone healing. This paper tests a novel fixation construct that aims to reduce stiffness while retaining the increased strength provided by locking constructs.
Methods:
This paper compares a novel fixation construct to traditional locking plate constructs in a bridge plating application. The novel system was designed with a screw that has a thinner, more flexi-ble shaft, and threads that only purchase the cortex opposite the plate. The heads of the novel locking system were designed to lock to the plate in the traditional locking fashion. The two plating systems were compared in a bridge plating fashion in synthetic diaphyseal bone.
Results:
The far-cortical locking system had axial stiffness measuring 88% lower than that of the regular locking system. In torsion and bending, the far cortical locking system was 58% and 29% less stiff respectively. Strength, however, was only 7% lower in non-osteoporotic bone. Under bend-ing and torsion, the far-cortical locking plates were 54% and 21% stronger respectively. Far-cortical locking also generated more axial motion at the fracture site.
Conclusions:
Use of far cortical locking facilitates axial motion in a bridge plating construct with only a mod-est reduction in strength. In this fashion, it more closely mimics the forces generated by an ex-ternal fixator. By allowing increased micro-motion at the fracture site, far-cortical locking may improve rates of osseous union in comminuted fractures.