TN-Advanced Tibial Nailing System
Christopher Finkemeier, Martin Hessmann, Mark Lee, Andrew Oppy, Karl Stoffel
Intramedullary nailing is becoming increasingly popular for proximal and especially distal tibial fracture fixation. However, expanding the nailing indications toward metaphyseal tibial fractures results in the challenge to fix short bone fragments with adequate stability. The new TN-Advanced (TN-A) Tibial Nailing System was specifically designed to address these issues. The new nail has preassembled polyether ether ketone inlays in the proximal and distal parts of the nail. When locking screws are inserted the inlays provide angular stability between the locking screws and the nail without the need for additional instruments and surgical steps.
Several improvements are introduced with the development of a new Low Profile Locking Screw in a headless design. Furthermore, the TN-Advanced Tibial Nailing System provides instruments for the infrapatellar, intraarticular suprapatellar, and extraarticular parapatellar approaches. The new suprapatellar TN-A instrumentation features a compressible and disposable suprapatellar sleeve that is designed to reduce the pressure on the patellofemoral joint whenever possible.
Nailing instruments
The new nailing instruments were developed to streamline the instrumentation and to eliminate redundancy between nailing system (Fig 1). The TN-A utilizes intuitive instrumentation aimed to improve operating room efficiency. Several innovative solutions address key functionalities of the instrumentation (Fig 2).
An important aspect for the development of the TN-A instrumentation was to provide instruments for the infrapatellar, intraarticular suprapatellar, and extraarticular parapatellar approaches.
Fig 1 There is a set of base instruments that is shared for the instrumentation of all nails of the Advanced Nailing System to reduce hospital storage requirements, system complexity, and staff learning efforts. 
Fig 2 Design features to optimize instrumentation. QUICK CLICK: attachment of the insertion handle to the nail (Fig 3); QUICK CONNECT LATCH: connection of the insertion handle to the aiming arm (Fig 4); TWIST & LOCK: protection sleeves are secured in the aiming arm with one quarter twist. 
Fig 3 QUICK CLICK. The nail is connected to the insertion handle by aligning the markings on the nail with the two slots on the barrel of the insertion handle and by pushing both parts together until they snap into place (a). The connection holds the nail in place until the connecting screw is tightened (b). 
Fig 4 QUICK CONNECT LATCH: The aiming arm is attached to the insertion handle (illustration for infrapatellar approach) by sliding it into the hook at the distal part of the insertion handle (1) and then rotating the latch toward the insertion handle (2) for both parts to connect. Suprapatellar insertion instruments
Dedicated suprapatellar insertion instruments have been available for the Expert Tibial Nail since 2012. These instruments comprise a soft outer protection sleeve to protect the patellofemoral cartilage and soft tissues as well as an inner metal protection sleeve through which the required cutting and reaming instruments and the nail can be inserted in a safe manner. However, the disadvantage of this instrumentation concept is that the pressure on the patellofemoral joint due to the presence of the sleeves is constantly kept at the same level and for the whole time until the nail is inserted. The new suprapatellar TN-A instrumentation features a compressible and disposable suprapatellar sleeve that is designed to reduce the pressure on the patellofemoral joint whenever possible (Fig 5). The sleeve expands as required by the size of the instruments as these are inserted through it. The compressible sleeve is provided in two sizes: small sleeve for nails with diameters of 8.211 mm and for reamer heads up to 12.5 mm; large sleeve for nails with diameters of 8.213 mm and for reamer heads up to 14.5 mm.
A multihole wire guide can be inserted through the protection sleeve to determine the correct entry point and entry path for the guide wire. This instrument can also be used before the insertion of the protection sleeve, thereby increasing the maneuverability of the wire guide in tight knees (Fig 6). Adjustments to the entry point location can be made by turning the multihole wire guide (Fig 7).
Once the protection sleeve is in its correct position it can be anchored to the femur via the protection sleeve handle using 3.2 mm K-wires. There are alternative protection sleeves available to allow anchoring to the tibial plateau (Fig 8).
The opening drill bit (rigid as well as flexible opening drill bits are available) and the reamers are pushed over the guide wire through the compressible suprapatellar sleeve. Drilling and reaming are supposed not to be started before the cutting instruments are placed down to the bone.
The surgical technique guides for instrumentation the TN-A with the various supported approaches were optimized based on anatomy lab experiences (Fig 9).
The TN-A may be removed by a suprapatellar or by a traditional infrapatellar approach. End cap removal and connection of the removal instrument to the nail is more difficult when using the suprapatellar approach for nail removal.
Fig 5 The amount of patellofemoral joint pressure depends on the sleeve size. Since the sleeve only expands when needed due to instrument presence, the pressure level on the cartilage and its duration are much lower compared with that induced by a rigid sleeve. 
Fig 6 Insertion of the wire guide through the protection sleeve (a) and wire guide placement without protection sleeve (b). 
Fig 7 The guide wire position can be adjusted by rotating the instrument around the first central guide wire. Thus, a second guide wire can be placed at 4 mm distance from the first guide wire to correct the position. 
Fig 8 Anchoring of the protection sleeve to the femur (a) and to the tibia (b) as an alternative fixation method. K-wire fixation to the femur allows higher sleeve stability. 
Fig 9 Review of the new suprapatellar nailing instrumentation in an anatomy lab by Christopher Finkemeier, INEG Chair. Innovations in nailing of tibial fractures: Tibia Nail Advanced
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