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Pearls and pitfalls with proximal third tibial fractures

By Douglas W. Lundy, MD, FACS, and Robert P. Dunbar Jr., MD

Seven suggestions for avoiding potential complications

Last month (AAOS Now, September 2007), we discussed pearls and pitfalls in the treatment of tibial plateau fractures. This month, the focus is on proximal third tibial fractures, such as the one depicted in Figure 1. This fracture of the proximal tibial metadiaphysis had been nailed 6 months previously. The patient had obvious angulation of the leg, a limb-length discrepancy, and significant pain with ambulation.

Unfortunately, complications after intramedullary fixation of proximal tibial fractures are all too common. Unless the orthopaedic surgeon consciously and actively addresses potentially deforming factors such as valgus, flexion, (apex anterior) angulation, shortening, and posterior translation of the distal fragment, this fracture may result in a reduction that is unacceptable and disconcerting to both the surgeon and the patient. With careful attention to detail, however, the orthopaedic surgeon may successfully treat these fractures with intramedullary nails.1 The following points may be helpful in avoiding potential complications.

Recognize potential problems when nailing these fractures
Most proximal third tibial shaft fractures nailed in valgus and flexion are not recognized as “proximal” tibial fractures with the potential for complications such as angulation and posterior translation.

Orthopaedic surgeons must recognize that tibial shaft fractures proximal to the isthmus of the tibia may angulate during intramedullary fixation due to the voluminous area of the proximal tibial metaphysis. Unless surgeons recognize the possibility of this deformity, they may be relatively unprepared to prevent it.

Use an appropriate nail
Different tibial intramedullary nails have the necessary bend (Herzog curve) at different points along their length. Maintaining this curve proximal to the fracture will minimize the deforming forces. If the bend of the nail progresses distal to the fracture as the nail is seated, a wedge effect may occur, contributing to posterior translation of the distal segment.

Use an appropriate starting point
Preventing the fracture from angulating into valgus is difficult if the surgeon uses a relatively medial starting point in the proximal tibia. In their letter to the editor of the Journal of Orthopaedic Trauma, Schmidt et al stated that the starting point should be “high on the tibia, at the edge of the articular surface of the knee, just medial to the lateral tibial spine.”2

Using a relatively lateral starting point is important to successful intramedullary fixation of proximal tibial fractures. The proximal extent of the tibial diaphysis actually “lines up” under the anterolateral aspect of the tibial plateau. By understanding this spatial relationship, orthopaedic surgeons can better appreciate the ideal starting point for the nail. Surgeons may use a medial parapatellar incision, a tendon-splitting approach or a lateral parapatellar arthrotomy to reach the appropriate starting point.

In addition to being relatively lateral, the starting point should also be high on the tibia, essentially adjacent to the articular surface. Unless the surgeon is using the semi-extended technique of intramedullary fixation, the patient’s knee should be maintained in flexion. With the knee in flexion, the high starting point allows for a pathway more in line with the long axis of the tibia. A low starting point or an extended knee allows the patella to push the guidewire distally and anteriorly, directing the pathway more toward the posterior cortex of the tibia, where it may accentuate the flexion deformity, cause posterior translation of the distal segment, or penetrate the posterior cortex. Because hyperflexion may accentuate the flexion deformity, surgeons should position the knee in slightly less flexion after identifying the starting point to minimize the influence of the extensor mechanism.

Guidewire, reamer, and nail must not only enter the bone from an appropriate position, they should exit and reenter major fragments concentrically. Proximal third metadiaphyseal fractures are commonly moderately long, oblique fractures, along a line from proximal lateral to distal medial. If the nail “leaves early” through the deficient lateral cortex in the proximal fragment, the proximal segment will adopt a valgus position.

Reduce the fracture before reaming
Although this seems obvious, tremendous problems can occur if the canal is prepared or the nail is advanced before the fracture is reduced. The nail will easily go only where the reamers were, and the reamers will go only where the guidewire was placed.

If the guidewire is not in the correct position before reaming, a satisfactory reduction will be extremely difficult to attain. If the fracture is reamed in a deformed position, the surgeon will struggle greatly to get the nail to follow a different course in the tibia. The nail will not reduce a nonisthmal fracture.

Prevent the deformity from happening
Several methods can be used to prevent deformity, including nailing the tibia with the knee in extension, plating the anterior tibial cortex, using blocking screws, or using modifications of these techniques.

Extending the knee: Tornetta and Collins have described a semi-extended technique of nailing fractures of the proximal tibia with the knee positioned in 15 degrees of flexion, rather than in hyperflexion.3 They used a medial parapatellar incision and subluxated the patella laterally. Because the force of the patellar ligament on the proximal fragment contributes to the anterior angulation deformity commonly seen after nailing proximal tibial fractures, limiting knee flexion to only 15 degrees neutralizes this force and prevents the deformity. In their study, none of the tibial fractures nailed in the semi-extended position had more than 5 degrees of apex anterior angulation.

Plating the cortex: Using a small plate to secure the anterior cortex of the tibia will maintain the fracture reduction during reaming and nail placement. In a study of 32 proximal tibial fractures, Lang et al found that a small plate, such as a six-hole, one-third tubular plate, placed extramedullary and anteriorly on the anterolateral tibial cortex, will not impede the placement of an intramedullary nail.4 Transcortical or unicortical screws are typically used to hold the plate in place.

The plate is placed through the same small incision used to obtain and maintain fracture reduction. Because the stability of the reduction is somewhat tenuous, orthopaedic surgeons should take care when manipulating the leg and inserting the nail. The plate should be placed before inserting the guidewire so that no eccentric reaming occurs. The plate may be removed, but is usually left in place. In our experience, these short plates do not provide sufficient rigidity to prevent callus formation at the fracture site and secondary bone healing.

Using blocking screws: Blocking screws are an elegant and minimally invasive adjunct to prevent valgus and flexion deformities when nailing proximal tibial fractures (Figure 2). This concept was first popularized by Krettek et al in 1999.5 They called the screws “poller screws” because the screws guided the nail like the “poller” traffic control devices guide traffic in Europe.

In these proximal tibial metadiaphyseal fractures, the nail is typically significantly smaller than the intramedullary canal at this level. This may allow the proximal segment to drift, because the nail may not have dominant purchase on the proximal segment. The key to using blocking screws successfully in this setting is to use them to narrow the effective canal of the proximal trumpet-shaped metaphyseal fragment to an appropriate corridor for the nail to pass. Screws should be applied to facilitate maintaining the nail in correct alignment in the short proximal segment. One rule of thumb is to apply the screws on the concave side of a deformity.6

Commonly, the nail passes along the posterior cortex in these fractures, which allows the proximal fragment to assume an extended or apex posterior position. Placing a blocking screw from medial to lateral and having the nail pass anteriorly to this screw forces the nail anteriorly in the canal and can prevent a sagittal plane deformity. The surgeon must place the screw far enough anteriorly to have the desired effect, while allowing room for the nail to pass in front of it (Figure 3).

Similarly, anterior to posterior blocking screw(s) may be placed in the proximal fragment to limit the effective canal, to buttress the nail, and, in so doing, to maintain proper alignment in the coronal plane. For proximal tibial fractures, the screw would be placed lateral to the nail on the concave side of the anticipated valgus deformity.

Of course, each case must be approached individually. If a varus deformity exists, or if an overly aggressive anteroposterior screw forces the nail too far medially, the surgeon may place a second anteroposterior screw slightly more distally and medial to the nail to ensure that the nail passes through the proximal fragment in the proper alignment and to permit an anatomic reduction of the fracture.

The interlocking screws for the particular nail system being used, inserted before placing the guidewire, are usually sufficient to serve as blocking screws. Surgeons must be careful not to damage or loosen the screws or reamers when reaming and inserting the nail.

Lock the proximal aspect of the nail
Stabilizing a proximal tibial fracture construct with only one proximal interlocking screw is inadequate and may result in loss of reduction. In a cadaveric biomechanical study, Laflamme et al showed that the addition of oblique proximal interlocking screws significantly increased the stability of the construct compared to a standard proximal interlocking screw.7 Once the fracture is reduced and the nail is in place, the reduction must be maintained. Use as many interlocking screws as necessary to stabilize the proximal fragment.

Fix any deformity as soon as possible
Orthopaedic surgeons who notice that the tibia is nailed in a malreduced position should correct the situation as soon as possible. If the patient is still in the operating room and the surgeon notices that the fracture is nailed in valgus and apex anterior angulation, he or she should remove the nail and try the aforementioned tips or consider plate fixation of the fracture.

If the patient’s deformity is recognized after surgery, the problem should be corrected as soon as possible. A surgeon who does not feel comfortable correcting the malalignment should refer the patient to a trauma specialist. Patients with a malreduced fracture will usually appreciate the referral. A surgeon who ignores the issue may be perceived as trying to cover up his or her mistakes.

Dr. Lundy is an orthopaedic surgeon with Resurgens Orthopaedics in Atlanta, Georgia and is a member of the Medical Liability Committee. Dr. Dunbar is an Assistant Professor at Harborview Medical Center/University of Washington.

References:

  1. Buehler KC, Green J, Woll TS, Duwelius PJ: A technique for intramedullary nailing of proximal third tibia fractures. J Orthop Trauma 1997;11:218-223.
  2. Schmidt AH, Templeman DC, Tornetta P, Webb LX, Bone LB, Duwelius PJ: Comment on: Anatomic assessment of the proper insertion site for a tibial intramedullary nail. J Orthop Trauma 2003;17:75-76.
  3. Tornetta P, Collins E: Semiextended position of intramedullary nailing of the proximal tibia. Clin Orthop Relat Res 1996;328:185-189.
  4. Lang GL, Cohen BE, Bosse MJ, Kellam JF: Proximal third tibial shaft fractures. Should they be nailed? Clin Orthop Relat Res 1995;315:64-74.
  5. Krettek C, Miclau T, Schandelmaier P, Stephan C, Möhlmann U, Tscherne H: The mechanical effect of blocking screws (“Poller screws”) in stabilizing tibia fractures with short proximal or distal fragments after insertion of small-diameter intramedullary nails. J Orthop Trauma 1999;13:550-553.
  6. Stedtfeld HW, Mittlmeier T, Landgraf P, Ewart A. The logic and clinical applications of blocking screws. J Bone Joint Surg Am 2004;86:17-25.
  7. Laflamme GY, Heimlich D, Stephen D, Kreder HJ, Whyne CM: Proximal tibial fracture stability with intramedullary nail fixation using oblique interlocking screws. J Orthop Trauma 2003;17:496-502.

October 2007 AAOS Now
http://www.aaos.org/news/bulletin/oct07/managing5.asp