Surgical Implant Generation Network (SIGN) was founded 15 years ago to create equality of fracture care throughout the world. This is done by education and supply of the appropriate implants and instruments to implement the education. SIGN implants have been used in 150,000 long bone fractures in developing countries. The same implants and instruments are used to provide intramedullary nail interlocking screw fixation in the tibia, femur, and humerus. The design of SIGN implants and the surgical technique are described.
Key points
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Education and implants that can be used without power equipment are key to enable interlocked intramedullary nailing without fluoroscopy in developing countries.
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The same implants and instruments are used to treat all long bone fractures.
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Open reduction is usually necessary.
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Results of Surgical Implant Generation Network surgery are equivalent to series of other implants in developed countries.
Orthopedic clinics: interlocked intramedullary nail without fluoroscopy
Five key points must interconnect to enable interlocked intramedullary nailing without fluoroscopy in developing countries:
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Patients who need this technology
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Skilled surgeons who understand the need for intramedullary nail interlocking screw system to treat their patients
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Appropriate implants designed to be used in austere environments
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Appropriate instruments designed for these implants and other conditions in austere environments
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Education for the surgeons using these implants and instruments
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Validation of surgical results using these implants and instruments.
Increasing Numbers of Patients with High-Energy Fractures
The numbers of patients in developing countries who need stabilization of high-energy fractures due to road traffic accidents are predicted to increase 67% by the year 2020. Every year, 20 to 50 million people are injured or disabled by road traffic accidents. Global conflicts are causing increasing numbers of fractures. Blast injuries are an extreme example of high-energy open fractures. The SIGN system is being used to treat civilians in Iraq, Afghanistan, Syria, South Sudan, and Pakistan, and is used in hospitals in 48 other developing countries.
Collaboration with Surgeons in Developing Countries
The development of the SIGN system has been facilitated by the combined efforts of many surgeons throughout the world. These surgeons work hard to treat the increasing number of severe fractures. They work hard because there are not enough orthopedic surgeons in developing countries.
Not only do these surgeons have an increasing number of patients with high-energy fractures to treat but treatment of these fractures is more difficult because the patients often have surgeries 2 to 6 weeks after injury. Surgical reduction of these fractures takes longer as the number of patients awaiting surgery increases ( Fig. 1 ).
SIGN was originally designed for stabilization of tibia fractures because a delay in treating an open tibia fracture has serious consequences for the patient. In developing countries, the patient and the family must purchase their implant before surgery can be done. This delays surgery while the funds for the implant are gathered by the family. SIGN was founded when we observed the need to combine education with the appropriate implants to implement the education. In 2011, 2.8 billion people in the world were living on less than 2 dollars per day and, therefore, could not afford the proper implant to stabilize the fracture.
Often, no fluoroscopy is available. Surgeons must use tactile sense to substitute for the visual images seen on C-arm screens. They feel vibrations coming from the far end of the instrument and internally visualize the location of the far end of the instrument instead of concentrating on the near end of the instrument while looking at a fluoroscopy image. For example, during reaming, they recognize the tactile difference as the increasing size of the reamers become tighter in the canal and produce chatter. They place the interlocking screws accurately and efficiently using instruments designed to be guided by tactile sense.
Surgical Implant Generation Network Technique for Tibial Nailing
The SIGN technique can be used in treatment of a high-energy tibia fracture or fractures of the femur and humerus.
A fractured tibia can be treated by closed reduction within 1 week of injury ( Fig. 2 ). Tactile sense facilitates this reduction. The hand reamers and nail are passed across the fracture site using vibratory sense. Development of tactile sense is procedural memory similar to riding a bicycle. The vibrations from the seat and handlebars keep us from falling off. This ability to feel vibrations and discern their meaning is not easily forgotten. Procedural memory allows a person to return to riding a bicycle years later without falling.
Reduction is accomplished by closed methods if possible. It is very difficult to reduce a fractured tibia closed 10 days after surgery. The fracture is stressed in all directions before attempting reduction; these maneuvers are repeated during reaming and placement of the nail. The surgeon has a baseline of instability before reduction and can judge when the reamers and the nail have been inserted past the fracture site.
The bone entrance is made through a longitudinal incision in the patella tendon. A guidewire is not used to determine the proper location because there is no fluoroscopy. The bone entrance is made with a curved awl that is also used to contour the channel anteriorly for 4 cm. This anterior channel created by the curved awl makes posterior penetration of the nail less likely. The fat pad is not disturbed.
The 7 to 9 mm reamers are pointed and the 10 to 14 mm reamers are blunt tipped ( Fig. 3 ). The reamers are guided down the canal using tactile sense. If the tibia fracture is in the proximal third, the Fig. 4 position is used for reaming and placement of the nail. Pressure is placed posteriorly on the proximal fracture if the fracture site is apex anterior. A blocking screw can be used for proximal tibia fractures; however, it is usually not necessary using Fig. 4 position. After the pointed reamers have been passed, the surgeon passes the blunt-tipped reamer through the fracture site, stopping at the subchondral bone. This maneuver is used to determine the length of the nail. Reaming continues until chatter occurs for 4 cm in the canal. The nail chosen is 1 to 2 mm smaller than the largest reamer used. Advantages of hand reaming include
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The bone from the flutes of the reamers is saved and placed in the fracture site if an open reduction is done
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The canal is contoured for a straight nail due to the progressive increasing size of the reamer shaft and tip; 3-point fixation occurs with the straight nail and curved canal.
The SIGN nail is a solid, straight nail made from stainless steel (see Fig. 4 ). If a guide pin and fluoroscopy are not used, there is no reason to use a hollow nail. A solid nail has less surface area on which biofilm can adhere. The SIGN nail reports on the surgical database were queried by Young and colleagues. Studies show that a hollow nail must be 2 mm larger in diameter to equal the strength of a solid nail. The solid nail allows slots to be used instead of than circular holes. This slot allows for slight compression during weightbearing for faster healing. The slots are large enough to accommodate the SIGN interlocking screws, which have a 4.5 mm shaft. The configuration of the slot is used to mechanically find its location.
The SIGN nail is straight. The 9° proximal bend in the nail provides rotational stability and provides a better canal fit in the proximal tibia. The 1.5° degree distal bend gives better vibratory feedback to the surgeon who rotates the nail as it proceeds down the canal. The same nail is used for left and right sides and for fractures of the tibia and femur, including retrograde, antegrade, and humerus. There is no increase in nail diameter of the proximal end.
Once the nail size has been chosen, it is attached to the L-handle. The target arm is adjusted to align the holes in the target arm with the slots in the nail. The target arm only determines the longitudinal orientation of the nail. If the nail bends during insertion, the nail rotates, which changes the orientation of the slots in relationship to the hole made in the near cortex. The slot finders accommodate for this change in rotation.
The nail is introduced into the bone entrance with enough flexion of the knee to prevent impingement by the patella. The distal 1.5° bend provides more tactile feel as the surgeon rotates the nail during passage down the canal. Rotation of the nail plus the 1.5° degree bend results in less possibility of penetration of the nail through the fracture site. Usually the nail is inserted by axial pressure and rotation. If a mallet is used, the authors suggest 2 small taps followed by rotation of the nail during insertion.
Once the nail has been placed, the target arm is reattached to locate the distal interlocking screw slots. The distal interlocking screws are inserted first so the surgeon can rotate the nail as needed. A cannula is placed on the bone and the drill guide placed through the cannula, which guides the drill through the near cortex. This pilot hole is enlarged by a step drill, which is turned by hand. The hole in the near cortex can be chamfered using the screw-hole broach. Chamfering removes the ring of bone at the bottom of the hole in the near cortex and redirects the direction of the opening. The solid slot finder is then placed in the hole to locate the slot in the nail ( Fig. 5 ). If the slot is located, the solid slot finder is replaced by the cannulated slot finder, which guides the location of the hole in the far cortex ( Fig. 6 ).
The depth gauge measures the width of the bone. The interlocking screw chosen is 4 mm longer than the measurement so that 2 threads are prominent on both sides of the canal. The SIGN interlocking screw has threads on both ends, with the threads on the near cortex enlarged to accommodate the enlargement of the hole made by the step drill ( Fig. 7 ).
The second interlocking screw is then placed in a similar manner. The alignment pin is placed in the hex of the screw to help guide the process.
If the hole is drilled and the solid slot finder does not enter the slot in the nail, the longitudinal alignment between the target arm and the hole in the near cortex is evaluated by determining whether the fracture fragments have changed position or the nail has changed position after the hole has been made. After longitudinal alignment has been confirmed, rotational malalignment is corrected. The target arm is removed, a curved slot finder is placed in the hole, and the nail is rotated, which allows the slot finder to enter the slot in the nail ( Fig. 8 ). The hole in the near cortex and the slot in the nail are now aligned and the cannulated slot finder is placed to guide drilling of the hole in the far cortex.
The proximal interlocking screws are placed using the target arm without the slot finders. Slot finders are not needed because the distance between the L-handle and the holes is less and, therefore, more accurate. Rotational malalignment does not occur in the proximal end of the nail.
The authors suggest placing 2 screws when the fracture is within 6 cm of the interlocking slots or when the screws go through the metaphysis. Accurate reduction plays a major role in providing and maintaining stability.
One absolute indication for stabilizing the fibula is if the fibula fracture fragments are overlapping. If they are overlapping, the fracture is in valgus. The authors are assessing other indications by observing follow-up on the SIGN surgical database. There are many variables.
Floating knees, or fracture of tibia and femur in the same patient, is common due to motorcycle injuries. These fractures can be reduced and stabilized at the same time in the supine position. The same incision longitudinally through the patellar tendon for nail insertion can be used, or an incision may be made medial to the patella tendon. A window in the fat pad must be created for the retrograde approach to the femur.
Education
Education regarding fracture care is interconnected. SIGN surgeons all learn from each other. The SIGN surgical database facilitates communication between surgeons. The operating surgeon describes reasons for his or her surgical decisions in the comment section along with preoperative and postoperative radiographs. Many questions are resolved by the follow-up radiographs and reports, which are the orthopedic surgeons’ report card. Often these findings lead to clinical studies that are presented at regional conferences throughout the world. Surgeons from developing countries present most of the papers during these conferences and the annual SIGN conference in Washington state in the United States ( Fig. 9 ). We strive to engage all attendees.
