Despite poor early results with intramedullary nailing of extra-articular proximal tibia fractures, improvements in surgical technique and implant design modifications have resulted in more acceptable outcomes. However, prevention of the commonly encountered apex anterior and/or valgus deformities remains a challenge when treating these injuries. It is necessary for the surgeon to recognize this and know how to neutralize these forces. Surgeons should be comfortable using a variety of the reduction techniques presented to minimize fracture malalignment.
Key points
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Despite poor early results with intramedullary nailing of extra-articular proximal tibia fractures, improvements in surgical technique and implant design modifications have resulted in more acceptable outcomes.
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Prevention of the commonly encountered apex anterior and/or valgus deformities remains a challenge when treating these injuries.
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It is necessary for the surgeon to recognize that prevention of apex anterior and/or valgus deformities presents a constant challenge and it is their responsibility to know how to neutralize these forces.
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Surgeons should be comfortable using a variety of the reduction techniques presented to minimize fracture malalignment.
Introduction
Proximal tibia fractures have presented a treatment challenge for orthopedic surgeons. Soft tissue concerns with open plating techniques resulted in the increased use of either percutaneous plating methods or intramedullary nail (IMN) fixation, which has the added benefit of being a load-sharing device to allow early weight bearing. Malalignment was common with early nailing techniques and implant designs as demonstrated by several series published during the 1990s. In a radiographic analysis of 133 tibia fractures treated with IMN fixation, Freedman and Johnson reported that 7 (58%) of the 12 proximal tibia fractures were malaligned, compared with an overall malalignment rate of all tibia fractures of 12% in the study. This experience was shared by Lang and colleagues who evaluated the results of 32 extra-articular proximal third tibia fractures treated with an IMN. At final follow-up, 27 (84%) of 32 fractures were malaligned more than 5° in the sagittal or coronal plane. As a result, the authors stated that they have limited their use of IMN for proximal third fractures.
The common deformity seen in proximal third tibia fractures is an apex anterior and/or valgus deformity. There are two main factors that complicate reduction of extra-articular proximal tibial fractures when treated with closed IMN: deforming forces of the proximal tibia (mainly extension of the proximal segment caused by pull of the extensor mechanism, but also forces from pull of the hamstrings and iliotibial band in different patterns); and the spaciousness of the intramedullary canal proximal to the metaphyseal flare.
IMN fixation offers several significant advantages over other treatment methods, such as plate fixation, because patients can be allowed to weight bear earlier and the surgery can be performed without making large skin incisions over a potentially compromised soft tissue envelope. The clinical benefits of treating these injuries with IMNs led surgeons to make implant design modifications and improve surgical techniques to yield the results we have today with malalignment rates of less than 8% in several recent series.
Introduction
Proximal tibia fractures have presented a treatment challenge for orthopedic surgeons. Soft tissue concerns with open plating techniques resulted in the increased use of either percutaneous plating methods or intramedullary nail (IMN) fixation, which has the added benefit of being a load-sharing device to allow early weight bearing. Malalignment was common with early nailing techniques and implant designs as demonstrated by several series published during the 1990s. In a radiographic analysis of 133 tibia fractures treated with IMN fixation, Freedman and Johnson reported that 7 (58%) of the 12 proximal tibia fractures were malaligned, compared with an overall malalignment rate of all tibia fractures of 12% in the study. This experience was shared by Lang and colleagues who evaluated the results of 32 extra-articular proximal third tibia fractures treated with an IMN. At final follow-up, 27 (84%) of 32 fractures were malaligned more than 5° in the sagittal or coronal plane. As a result, the authors stated that they have limited their use of IMN for proximal third fractures.
The common deformity seen in proximal third tibia fractures is an apex anterior and/or valgus deformity. There are two main factors that complicate reduction of extra-articular proximal tibial fractures when treated with closed IMN: deforming forces of the proximal tibia (mainly extension of the proximal segment caused by pull of the extensor mechanism, but also forces from pull of the hamstrings and iliotibial band in different patterns); and the spaciousness of the intramedullary canal proximal to the metaphyseal flare.
IMN fixation offers several significant advantages over other treatment methods, such as plate fixation, because patients can be allowed to weight bear earlier and the surgery can be performed without making large skin incisions over a potentially compromised soft tissue envelope. The clinical benefits of treating these injuries with IMNs led surgeons to make implant design modifications and improve surgical techniques to yield the results we have today with malalignment rates of less than 8% in several recent series.
Implant design
Some reasons for failure in treatment, defined by malalignment or loss of fixation, can be in part attributed to early implant design. Early generation tibial nails had a proximal sagittal bend (Herzog curve) that was larger than currently available nails, and/or had a bend that extended distal to the fracture site. Both of these design characteristics contribute to what Henley and coworkers referred to as the “wedge effect,” which occurs as the nail is seated and impinges on the posterior cortex of the distal segment accentuating an apex anterior deformity because of the effective widening of the nail above the bend and posterior force on the distal segment to match the nail shape.
Additional reasons for early fixation failure in these fractures have been attributed to use of a single proximal interlocking bolt, or use of the dynamic interlocking mode. Both Henley and coworkers and Laflamme demonstrated the problems associated with limited fixation in the proximal segment, and implant modifications to include additional oblique/multiplanar interlocking bolt options have minimized loss of fracture reduction.
Further modifications to IMN design have included the addition of angular stable locking screws that thread into the nail. Although they seem to offer additional stability, especially in osteoporotic bone, when compared with conventional implants (nonthreaded locking holes) using a biomechanical proximal tibia fracture model they offered no extra benefit.
Nail starting point
The starting point should be just medial to the lateral tibia spine on the anteroposterior (AP) fluoroscopic image (ensure appropriate rotation using the fibular bisector line or the “twin peaks” view) and just anterior to the articular surface on the lateral fluoroscopic image (“flat plateau”). Obtaining the correct starting point is important for nailing proximal tibia fractures for two reasons. First, just as in standard nailing for tibia fractures, the surgeon should avoid damage to the intra-articular structures. Tornetta and colleagues have detailed the safe zone for tibial nailing, which is 9.1 ± 5 mm lateral to midline of the plateau and 3 mm lateral to the center of the tubercle. The width averaged between 22.9 and 12.6 mm. A follow-up study was performed to identify the fluoroscopic images that correlate with the appropriate safe zone. Kirschner wires were placed in cadaveric knees under direct visualization of the safe zone, and then radiographs were obtained that demonstrated that the safe zone is just medial to the lateral tibial spine on the AP and just anterior to the articular surface on the lateral image. There was some variance on the AP, but no variance on the lateral image.
A recent study confirmed the importance of obtaining appropriate intraoperative fluoroscopic images, because a slight external rotation of the proximal tibia when obtaining fluoroscopic images of the starting point can result in a misleading medial entry point, which may accentuate a valgus deformity. The authors of this study used the fibular bisector line (overlap of the lateral border of the tibia bisecting the fibula head) as a reliable intraoperative fluoroscopic confirmation of appropriate rotation because the entry point using this image was always either ideal or less than 5 mm lateral to the ideal entry point, but never medial. Because of the potential valgus deformity obtained with intramedullary nailing of proximal tibia fractures, avoidance of a medial starting point is paramount.
An alternative method for ensuring appropriate rotation on intraoperative fluoroscopic images is use of the twin peaks AP view and flat plateau lateral view. A cadaveric study demonstrated excellent intraobserver and interobserver reliability with use of this technique compared with use of the fibular bisection line on the AP view and perfectly aligned femoral condyles on the lateral view, allowing for accurate identification of the starting point. The twin peaks AP view simply obtains the sharpest profile of the tibial spines and the flat plateau lateral view lines up the posterior aspect of the femoral condyles and then adducts the limb to line up the medial and lateral tibial plateaus ( Figs. 1 and 2 ).
Nailing techniques
Nailing in Flexion
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Hyperflexion permits accurate guidewire placement and alignment in sagittal plane.
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The incision can be medial, through, or lateral to the patellar tendon to facilitate accurate pin placement.
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Ensure trajectory of guidewire or awl is correct on intraoperative fluoroscopy before reaming the proximal tibia.
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Fracture must be reduced before canal preparation (reaming) and implant placement.
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Place locking bolts with limb in extension (the position of reduction).
The traditional method of nailing tibia fractures, regardless of location of the fracture, has been to nail in flexion. Hyperflexion of the knee allows accurate placement and alignment of the guidewire in the sagittal plane, nearly parallel to the anterior cortex. The incision is most commonly medial to the patellar tendon, but can be midline or even lateral to the tendon in certain cases to facilitate accurate pin placement and minimize interference from the extensor mechanism. After preparation of the entry portal, it is important to extend the knee for reduction, canal preparation, and placement of the interlocking bolts. This balances the deforming forces on the proximal tibia in the sagittal plane to assist in maintenance of reduction. However, it must be emphasized that the fracture should always be reduced before or while reaming and nailing, because simply extending the leg without using proper technique throughout the procedure does not compensate for the resultant deformity with nail passage. This point likely led to modifications to the implant system and surgical technique to accommodate nailing in the semiextended position, making it easier to keep the fracture reduced while reaming and during passage of the IMN.
Nailing in Semiextended Position
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Limit flexion to approximately 15° to neutralize the force of the extensor mechanism on the proximal tibia leading to an apex anterior deformity, and to relax the tissues allowing for easier instrumentation in proper alignment. The slight flexion allows access to the proximal tibia to obtain the correct starting point.
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This can be done with small radiolucent bump or triangle behind the knee, which allows for slight flexion. In addition, the use of an elevated radiolucent leg ramp elevates the injured extremity above the contralateral leg, making intraoperative fluoroscopy easier ( Figs. 3 and 4 ).
Fig. 3
Use of a radiolucent ramp under the operative extremity aids in achieving slight knee flexion while elevating the operative extremity above the contralateral limb, making intraoperative fluoroscopy easier.
Fig. 4
A bump placed under the knee may be used to aid in obtaining optimal knee flexion to obtain the correct starting point.
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The approach can be made medial or lateral to the patellar tendon depending on which way it is easier to subluxate the patella.
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Trochlear groove used as an alignment guide for instrumentation.
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Ensure trajectory of guidewire or awl is correct on intraoperative fluoroscopy before reaming the proximal tibia.
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Fracture must be reduced before canal preparation (reaming) and implant placement.
Tornetta and Collins were one of the first to describe nailing proximal tibia fractures in the semiextended position with the use of an arthrotomy. Of 25 patients with proximal tibia fractures treated with IMNs by this technique, 19 had anatomic alignment in the sagittal plane, and none had greater than 5° malalignment in the sagittal plane. Two of the 25 had coronal plane deformities greater than 5°. In a prospective study, Vidyadhara and Sharath had a 16% malunion rate in 7 of 45 patients with proximal tibia fractures treated with intramedullary nailing in the semiextended position, three in valgus and four apex anterior greater than 5°. Variations of this semiextended technique have been reported with the use of extra-articular approaches.
Suprapatellar Nailing
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Similar amount of knee flexion (15°) required as in semiextended to neutralize the force of the extensor mechanism on the proximal tibia leading to an apex anterior deformity. The slight flexion allows access to the proximal tibia to obtain the correct starting point.
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An elevated radiolucent leg ramp is used to elevate the injured extremity above the contralateral leg, making intraoperative fluoroscopy easier.
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A small radiolucent bump is required under the knee to obtain appropriate amount of knee flexion.
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Skin incision is approximately 2 cm in length, starting 2 cm above patella and extending proximally ( Fig. 5 ).
