The Size of Intramedullary Fixation Affects Endochondral-Mediated Angiogenesis During Fracture Repair

Management of Segmental Tibial Bone Defects With the Magnetic Motorized Intramedullary Transport Nail: A Case Series

SUMMARY

Critical-sized bone defects in the tibia can arise as sequelae of trauma, infection, tumor, or the treatment of congenital limb deficiencies. Treatment of these defects often requires bone transport, which has traditionally been accomplished using circular external fixators. The development of a bone transport nail facilitated tibia reconstruction through distraction osteogenesis using an all-internal device, thus avoiding the complications associated with chronic external fixation. Given the rarity of these cases, few studies have been published on the reconstruction outcomes using this implant. We sought to investigate the bone healing indices (including regenerate consolidation and time to docking site union) associated with the use of a magnetically controlled all-internal bone transport nail for the reconstruction of 4 patients treated for posttraumatic tibial bone loss. Perioperative and device-related complications are also reported.

Effect of Intramedullary Nailing Patterns on Interfragmentary Strain in a Mouse Femur Fracture: A Parametric Finite Element Analysis

Delayed long bone fracture healing and nonunion continue to be a significant socioeconomic burden. While mechanical stimulation is known to be an important determinant of the bone repair process, understanding how the magnitude, mode, and commencement of interfragmentary strain (IFS) affect fracture healing can guide new therapeutic strategies to prevent delayed healing or nonunion. Mouse models provide a means to investigate the molecular and cellular aspects of fracture repair, yet there is only one commercially available, clinically-relevant, locking intramedullary nail (IMN) currently available for studying long bone fractures in rodents. Having access to alternative IMNs would allow a variety of mechanical environments at the fracture site to be evaluated, and the purpose of this proof-of-concept finite element analysis study is to identify which IMN design parameters have the largest impact on IFS in a murine transverse femoral osteotomy model. Using the dimensions of the clinically relevant IMN as a guide, the nail material, distance between interlocking screws, and clearance between the nail and endosteal surface were varied between simulations. Of these parameters, changing the nail material from stainless steel (SS) to polyetheretherketone (PEEK) had the largest impact on IFS. Reducing the distance between the proximal and distal interlocking screws substantially affected IFS only when nail modulus was low. Therefore, IMNs with low modulus (e.g., PEEK) can be used alongside commercially available SS nails to investigate the effect of initial IFS or stability on fracture healing with respect to different biological conditions of repair in rodents.

Plate-Assisted Bone Segment Transport Versus Precice Bone Transport Nail

Management of segmental long bone defects is a complex and challenging undertaking for orthopaedic surgeons. These defects can be encountered in cases of high-energy trauma, tumor resection, or infection, and they are often associated with significant soft tissue injury. Traditional approaches of bone transport rely on external fixation and principles of distraction osteogenesis. Plate-assisted bone segment transport (PABST) using the Precice limb lengthening nail has been adapted for use in bone transport with the use of a plate in an effort to eliminate the need for external fixation and its associated complications. Recently, the arrival of the Precice Bone Transport (PBT) System intramedullary nail eliminates the need for plating and some of the problems encountered in PABST; however, it also introduces some new issues. PABST and the PBT nail have become viable alternatives to bone transport using a frame; however, each has its own unique set of advantages and disadvantages. Although the problems of using external fixation devices are eliminated with these techniques, there is less forgiveness in execution and very little chance of correcting as the transport is underway. The arrival of the PBT nail does not eliminate the need for PABST as seen by the difficulty maintaining alignment in short metaphyseal segments. This review reflects the current state of these methods based on available evidence; however, optimization of the protocol for transport using PABST and the PBT nail will require additional cases and data.