Introducing the “Bone-Screw-Fastener” for improved screw fixation in orthopedic surgery: a revolutionary paradigm shift?

Abstract

BackgroundConventional screws used for fracture fixation in orthopedic surgery continue to rely on the historic buttress thread design. While buttress screws generally provide solid resistance against unidirectional axial loading forces, their design suffers from several limitations, as the buttress thread does not adequately resist multiaxial forces. Furthermore, the buttress screw is prone to stripping at the bone-screw interface and can cause microfracturing of the surrounding bone due to its thread design. Standard buttress screws are therefore at risk of adverse postoperative outcomes secondary to failure of bone fixation. A new patented Bone-Screw-Fastener was recently designed that is based on an interlocking thread technology. This new fastener provides distributive forces from the threads onto the bone and therefore resists loads in multiple directions. The underlying concept is represented by a “female thread” bone cutting technology designed to maximize bone volume, preserve bone architecture, and create a circumferential interlocking interface between the implant and bone that protects the thread from stripping and from failing to multiaxial forces.Presentation of the hypothesisWe hypothesize that the new Bone-Screw-Fastener overcomes the classic shortcomings of conventional orthopedic screws with buttress threads by ease of insertion, improved bone preservation, increased resistance to off-axis multidirectional loading forces and to stripping of the threads. These advanced biomechanical and biological properties can potentially mitigate the classic limitations of conventional buttress screws by providing better resistance to implant failure under physiological loads, preserving bone biology, and thus potentially improving patient outcomes in the future.Testing the hypothesisThe presumed superiority of the new fastener will require testing and validation in well-designed prospective multicenter randomized controlled trials (RCTs), using the conventional buttress screw as control.Implications of the hypothesisOnce validated in multicenter RCTs, the new Bone-Screw-Fastener may drive a change in paradigm with regard to its innovative biomechanical principles and biologic bone preservation for surgical applications requiring screw fixation.

Influence of interlocking thread screws to repair simulated adult canine humeral condylar fractures

“…The proposed advantages of the interlocking thread design include improved resistance to multidirectional forces and improved resistance to stripping. 22 This hypothesis is supported by a recent study that demonstrated that ITS has higher torque stripping resistance than BTS. 42 Further studies are required to determine how the increased temperature and work generated during drilling and screw insertion impacts the ITS performance in a clinical setting.…”

“…The multidirectional thread pattern is also theorized to better resist multidirectional loads and better distribute loading forces across all thread surfaces compared to conventional buttress thread screws. 22 A proprietary drill bit whose drill point angles and drill body design differ from those of standard surgical drill bits was developed in conjunction with the ITS. Design changes were intended to improve clearance of bone debris from the drill hole and thus optimize the screw bone interface.…”

“…Design changes were intended to improve clearance of bone debris from the drill hole and thus optimize the screw bone interface. 22 The primary objective of this study was to determine the influence of interlocking screw threads on the biomechanical properties of repaired canine humeral condylar fractures. This was achieved by comparing the mechanical performance of 3.5 mm ITS and 3.5 mm BTS-L or BTS-P for stabilization of simulated adult canine humeral condylar fractures.…”

“…The ITS design is intended to improve implant‐bone interface stability by decreasing screw toggling and the development of microfractures. The multidirectional thread pattern is also theorized to better resist multidirectional loads and better distribute loading forces across all thread surfaces compared to conventional buttress thread screws 22 . A proprietary drill bit whose drill point angles and drill body design differ from those of standard surgical drill bits was developed in conjunction with the ITS.…”

An overview of thermal necrosis: present and future

“…Osteonecrosis potentially results in catastrophic failures of orthopaedic screw-bone constructs and sometimes even promotes infection [7]. In summary, the essential shortcomings of buttress threads include the risk of stripping, screw loosening, induction of stress risers, bone micro-fracturing, heat necrosis, with subsequent failure of fixation and risk of creating fracture nonunions and malunions [8]. In the field of articular cartilage repair, bone marrow stimulation is often performed using either a surgical twist drill bit or a Kirschner wire to introduce defined holes in the subchondral bone plate following meticulous removal of the calcified cartilage layer at the bottom of the defect.…”