Sunday, October 9, 2011

Intramedullary Nailing of Proximal Third Tibial Fractures: Techniques to Improve Reduction

Intramedullary Nailing of Proximal Third Tibial Fractures: Techniques to Improve Reduction
by David J. Hak, MD, MBA
Obtaining and maintaining an acceptable reduction of proximal third tibial fractures can be problematic. Deforming forces acting on the proximal fragment and the spaciousness of the intramedullary canal at this level contribute to this challenge during intramedullary nailing. Several surgical techniques have been developed to address this problem, including the use of a more lateral and proximal starting point, adjunctive plate fixation, blocking screws, semiextended nailing, and most recently the use of a retropatellar portal approach. Familiarity with these techniques is critical to achieve satisfactory results when nailing proximal third tibial fractures.
Intramedullary nailing of simple diaphyseal tibial shaft fractures usually results in near anatomic reduction, as the intramedullary nail fills the intramedullary canal. In contrast, accurate reduction of tibial fractures that are near the proximal metaphyseal junction are notoriously problematic when treated by intramedullary nailing (Figure ).
In the absence of special techniques to achieve and maintain accurate reduction, extra-articular proximal third tibial fractures treated with an intramedullary nail will commonly be malreduced in valgus, apex anterior, and have posterior displacement of the distal segment.
Two main factors complicate the reduction of extra-articular proximal tibial fractures: (1) the deforming forces acting on the proximal tibial segment; and (2) the spaciousness of the intramedullary canal at this level. Flexion of the knee is required to create a traditional intramedullary nail entry site in the proximal tibia. Because of the attachment of the patellar tendon to the proximal fracture segment, apex anterior displacement occurs (Figure ).
Starting Point Location
A more lateral and proximal entry site is helpful to avoid malreduction in proximal tibial fractures (Figure ). Proximally, the medial side of the tibia has been described as a chute that deflects the nail laterally. 4The central axis of the intramedullary canal is most commonly aligned with the lateral tibial eminence. Using a more proximal entry site will achieve a longer segment of nail within the proximal segment and usually place the nail’s Herzog bend completely within the proximal segment, rather than at or distal to the fracture site. Use a more lateral and proximal entrance site to achieve reduction of proximal tibial shaft fractures. Also may use a medially placed universal distractor and placed the interlocking screws with the knee in full extension using a special proximal interlocking jig. 
Adjunctive Plating
Temporary or permanently place a small fragment plate to maintain reduction of the proximal fracture and allow the knee flexion required to insert an intramedullary nail. 
Clinically, both one-third tubular and small-fragment compression plates have been used. Locking plates provide another useful option. A 4- to 6-hole plate is commonly used. The plate can be used temporarily and removed after the nail is successfully inserted and interlocked, or left in place to assist with maintaining the reduction. With the use of unicortical screws, the plate can be positioned along almost any surface. Good screw purchase can usually be obtained with a plate placed anteriorly in the area of thick cortical bone. Alternatively, the plate can be placed along the medial surface. In this case, bicortical screws may be placed from medial to lateral as long as they are anterior to the proximal path of the nail (Figure ).

Pollar / Blocking Screws


Poller or blocking screws to improve reduction in metaphyseal fractures treated with intramedullary nailing. The blocking screws essentially reduce the size of the available nail pathway. Properly positioned screws can prevent malreduction as a nail is placed into a large metaphyseal space. 
Proper placement of blocking screws can be difficult. If they are placed too close to the intended ideal nail pathway, the nail may not be able to be passed, while if they are placed too far from the intended ideal nail pathway, they will not adequately aid reduction of the fracture. Blocking screws can be placed preemptively to prevent known deformity. Alternatively, if a malreduction occurs during placement of an intramedullary nail, the nail can be extracted, the blocking screw(s) placed, and the nail reinserted (Figure ). Intraoperative fluoroscopy is routinely used to assess the optimal position for placement of a blocking screw. 
To prevent apex anterior deformity, a blocking screw is placed from medial to lateral just posterior to the intended ideal posterior location of the intramedullary nail (Figure ).

To prevent valgus angulation, a blocking screw should be placed just lateral to the central axis of the tibia (Figure ). As the nail is passed medial to the locking screw, the deformity is corrected. In contrast, to prevent varus angulation, which is less commonly seen in proximal tibial fractures, a blocking screw should be placed just medial to the central axis of the tibia.
Semiextended Nailing Technique
Use an extended incision, releasing the medial patellar retinaculum to allow subluxation the patella laterally to permit entry site creation and intramedullary nail insertion with the knee in only 15° of flexion. By moving the patella out of the way, the entry site can be obtained with the knee in near full extension, with the awl or opening drill flush up against the trochlear groove of the femur (Figure ).
Retropatellar Portal Technique
Most recently, a retropatellar portal technique has been developed for tibial nail insertion (Figure ). It provides the knee extension benefit of the semiextended nailing technique without the need for an extensile incision. In this approach, a suprapatellar incision is used and the quadriceps tendon fibers split longitudinally. A cannula is used to protect the patellar surface during passage of the entry drill, reamers, and tibial nail. While there are no reported long-term clinical outcomes of this technique, cadaveric investigations have shown it to be a safe technique.

Conclusion


Obtaining and maintaining an acceptable reduction of proximal third tibial fractures can be problematic. Deforming forces acting on the proximal fragment and the spaciousness of the intramedullary canal at this level contribute to this challenge during intramedullary nailing. Several surgical techniques have been developed to address this problem, including the use of a more lateral and proximal starting point, adjunctive plate fixation, blocking screws, semiextended nailing, and most recently the use of a retropatellar portal approach. Familiarity with these techniques is critical to achieving satisfactory results when nailing proximal third tibial fractures.


Medial Malleolar Fractures: A Biomechanical Study of Fixation Techniques

Medial Malleolar Fractures: A Biomechanical Study of Fixation Techniques
by T. Ty Fowler, MD; Kevin J. Pugh, MD; Alan S. Litsky, MD, ScD; Benjamin C. Taylor, MD; Bruce G. French, MD
DOI: 10.3928/01477447-20110627-09

Abstract

Fracture fixation of the medial malleolus in rotationally unstable ankle fractures typically results in healing with current fixation methods. However, when failure occurs, pullout of the screws from tension, compression, and rotational forces is predictable. We sought to biomechanically test a relatively new technique of bicortical screw fixation for medial malleoli fractures. Also, the AO group recommends tension-band fixation of small avulsion type fractures of the medial malleolus that are unacceptable for screw fixation. A well-documented complication of this technique is prominent symptomatic implants and secondary surgery for implant removal. Replacing stainless steel 18-gauge wire with FiberWire suture could theoretically decrease symptomatic implants. Therefore, a second goal was to biomechanically compare these 2 tension-band constructs.
Using a tibial Sawbones model, 2 bicortical screws were compared with 2 unicortical cancellous screws on a servohydraulic test frame in offset axial, transverse, and tension loading. Second, tension-band fixation using stainless steel wire was compared with FiberWire under tensile loads. Bicortical screw fixation was statistically the stiffest construct under tension loading conditions compared to unicortical screw fixation and tension-band techniques with FiberWire or stainless steel wire. In fact, unicortical screw fixation had only 10% of the stiffness as demonstrated in the bicortical technique. In a direct comparison, tension-band fixation using stainless steel wire was statistically stiffer than the FiberWire construct.
For unstable ankle fractures that involve the medial malleolus, operative treatment is generally recommended. 1–7 Multiple techniques, including bioabsorbable implants, 8 have been used for fixation of the medial malleolus; however, the most common technique as recommended by the Association for the Study of Internal Fixation (AO-ASIF) group uses two 4-mm partially threaded cancellous lag screws placed perpendicular to the fracture line. Stainless steel cancellous screws had up to 24% less pullout force, significantly less torsional and bending strength than a 3.5-mm bicortical screw.
The AO-ASIF group recommends tension-band wiring for small avulsion type fractures of the medial malleolus that are unacceptable for screw fixation as well as for osteoporotic bone. 5 A well-documented complication of tension-band fixation of the medial malleolus is prominent symptomatic hardware, largely due to the subcutaneous nature of the medial malleolus, that often requires a second operation for hardware removal. 2–4,12,13 Replacing stainless steel wire with Fiber-Wire (Arthrex Inc, Naples, Florida) suture could theoretically decrease the incidence of symptomatic hardware and therefore decrease secondary procedures.
Full Detail : http://www.orthosupersite.com/view.aspx?rid=86268