Intramedullary fixation of rib fracture with Kirschner wires (K-wires) has been practiced for over 50 years. However, this technique has neither been analyzed nor advanced to address reported complications of wire migration and cut-out. This biomechanical study evaluated rib fixation with K-wires. It furthermore evaluated a novel rib splint designed to replicate the less-invasive fixation approach of K-wires while avoiding their complications.
The durability, strength and failure modes of rib fracture fixation with K-wires and rib splints were comparatively evaluated in 22 paired human ribs. Fractures in fight ribs were stabilized with stainless steel K-wires of 1.5 mm diameter. Left ribs were stabilized with novel rib splints (MatrixRIB splint, Synthes CMF). These titanium splints had a rectangular cross-section to resist cut-out and a locking screw to prevent migration. All fixation constructs were loaded to 360,000 cycles at five times the respiratory load magnitude to determine durability. Finally, constructs were loaded to failure to determine their residual strength and failure modes.
All constructs sustained 360,000 loading cycles. Dynamic loading caused on average three times more subsidence in K-wire constructs (1.2 mm ± 1.4 mm) than in rib splint constructs (0.4 mm ± 0.2 mm, p=0.09). Construct strength after dynamic loading remained 48% greater in rib splint constructs than in K-wire constructs (p=0.001). Six K-wire construct failed by wire bending and five K-wire constructs failed catastrophically by cut-out through the medial cortex, leading to complete loss of stability. Rib splint constructs failed by mild splitting of the medial cortex or splint bending, which elastically recovered into a functional position. All splint constructs retained functional reduction and fixation of rib fractures after failure.
K-wires or rib splints provided sufficient durability to support respiratory loading throughout the healing phase.
Due to their superior strength and absence of catastrophic failure, rib splints can serve as an attractive alternative to K-wires for intramedullary stabilization of rib fractures in flail chest injury.
Michael Bottlang, Grant monies (from industry related sources) The authors received funding from Synthes CMF (West Chester, PA, USA) for the conduct of the presented research.; Consultant fee, speaker bureau, advisory committee, etc. The authors Bottlang, Madey, and Long receive consulting fees from Synthes CMF.; No Product/Research Disclosure Information