Orthopaedic trauma surgery in low-income countries

Recent developments on intramedullary nailing: a biomechanical perspective

“…The friction and an elastic union between the implant and the inner medullary cavity were responsible for limiting bone motion in relation to the nail. The resistance to rotation and axial motion at the fracture site was guaranteed by interdigitating of the fracture fragments and endosteal contact with the nail above and below the fracture site . Its relative simplicity—no need for external fixation, high joint mobility, early ambulation (patients were out of bed in a matter of days rather than months)—and the overall good results achieved comparatively to the frequent intervention of traction (or “extension” as it was often called) followed by casting guaranteed the worldwide success of Küntcher's nails …”

“…In the materials field, a strong novelty was also introduced in the 1990s with the adoption of titanium, a new material competing with the until then commonly used AISI 136 LVM ASTM F138 stainless steel (generally known as medical‐grade stainless steel) . Today, both materials are widely accepted; however, there is a preferential tendency for titanium alloy owing to its attractive mechanical properties (see Table ), such as Young's modulus closer to the intact diaphyseal cortical bone, higher fatigue strength and yield strength, and the fact that it is biocompatible and shows less magnetic resonance imaging interference than that observed for stainless steel implants . Today, the increased preference for limited reaming or “ream‐to‐fit” techniques allowed the adoption of anatomically smaller diameter nails, which in static locked mode provide a sufficiently large interfragmentary motion that favors callus development .…”

“…The earliest records of human attempts to deal with fracture come from the 16th century Aztec population, where resinous wood sticks were placed in the medullary canal for stabilization. [3][4][5][6][7] However, only decades later, during the 19th century, an increased interest in the potentialities of "intramedullary doi: 10.1111/nyas.13524 fixation" emerged. It started with ivory peg developments in patients with nonunions and not bone fractures.…”

“…The resistance to rotation and axial motion at the fracture site was guaranteed by interdigitating of the fracture fragments and endosteal contact with the nail above and below the fracture site. 3,[12][13][14][15] Its relative simplicity-no need for external fixation, high joint mobility, early ambulation (patients were out of bed in a matter of days rather than months)-and the overall good results achieved comparatively to the frequent intervention of traction (or "extension" as it was often called) followed by casting guaranteed the worldwide success of Küntcher's nails. 3,16,17 Another turning point in the history of intramedullary nail emerged in the 1950s with the introduction of flexible intramedullary reamers, again through Küntscher progressive thinking.…”

“…5,17,27,29 Today, both materials are widely accepted; however, there is a preferential tendency for titanium alloy owing to its attractive mechanical properties (see Table 1), such as Young's modulus closer to the intact diaphyseal cortical bone, higher fatigue strength and yield strength, and the fact that it is biocompatible and shows less magnetic resonance imaging interference than that observed for stainless steel implants. 3,14,[29][30][31][32] Today, the increased pref-erence for limited reaming or "ream-to-fit" techniques allowed the adoption of anatomically smaller diameter nails, which in static locked mode provide a sufficiently large interfragmentary motion that favors callus development. 10,21,32 Despite its effectiveness and reliability as a stabilization system, intramedullary nailing is still subject to constant upgrades that aim to improve the time and quality of the callus formation, as described below.…”