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Executive Editor: Peter Trafton

Authors: Martin Hessmann, Sean Nork, Christoph Sommer, Bruce Twaddle

Distal tibia 43-A1 MIPO

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Glossary

1 Single-stage or multiple-stage surgery? top

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Principles

By definition, type A fractures have no involvement of the articular surface, so accurate reduction of the joint is not required. Subgroup A1 refers to two-part fractures of the distal tibia.

The soft-tissue conditions usually dictate the choice of procedure: early single-stage or multiple-stage surgery. The decision is based on the individual situation and not necessarily on general principles. This type of fracture lends itself to MIPO type stabilization because of the minimum insult to the soft-tissue envelope.


Displaced type A fractures with minimal, closed soft-tissue injury

(Tscherne classification, closed fracture grade 0, rarely grade 1)

These injuries may be reduced and fixed primarily, as a single stage procedure, if the soft tissues are in truly excellent condition.

A distractor or external fixator may help reduction. Fibular reduction and fixation is the usual next step, but this reduction must be accurate, so that it does not prevent tibial reduction. Finally, the tibial plate is introduced with MIPO technique and final reduction of length, alignment and rotation is achieved.


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Grossly displaced fractures and/or fractures with severe, closed soft-tissue injury

(Tscherne classification, closed fracture grade 2 or 3)

It is generally advisable to proceed in two or more stages:

  1. Closed reduction and joint bridging external fixation
  2. Definitive MIPO reconstruction after 5-10 days (wait for the appearance of skin wrinkles)

 


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Open distal tibial fractures

Rarely, with open fractures of the distal tibia, if the fracture pattern is a simple type A1 fracture, direct reduction through the compound injury and absolute stability with compression plating is possible. Secondary soft-tissue reconstruction is still required. Often, definitive fracture stabilization should be delayed, until the time of definitive soft-tissue coverage. The management includes several stages:

  • Emergency management: Wound debridement and lavage. Joint-bridging external fixation and stabilization of the fibula (if needed and soft tissues allow). Where possible, closure or coverage of any opening into the joint should be achieved.
  • After 48 hours: Plan soft-tissue coverage (local or free flap).
  • Definitive stabilization at the time of soft-tissue coverage.

 

2 Planning for reduction and fixation top

Fibula or tibia first? Sequence of bone stabilization

In type 43-A1 fractures, the fibula may be fractured as well and needs to be stabilized.

For simple fibular fractures, this is usually done first with ORIF and stable plate fixation. Alternatively, for transverse fractures, consider a small diameter, flexible intramedullary nail. Fibular reduction helps realign the tibia fracture. The operation is completed by stable plate fixation of the tibia. Finally, bone grafting is performed if required.

Some fibular fractures are complex and reduction may be difficult. Their fixation will impede reconstruction of the tibia. In this situation, fibular ORIF is better after the tibia has been fixed. The syndesmotic ligaments are usually intact, so gross realignment of the fibula occurs with reduction and fixation of the tibia. An option, which is attractive for comminuted fibular fractures, is to use a MIPO technique with a long bridging plate, or intramedullary fixation of the fibula with a small diameter, flexible nail. Fibular nailing is particularly applicable if the soft-tissue injury or complexity of the fracture makes extensive exposure for internal fixation hazardous.


Preoperative planning

Preoperative planning is an essential part of treatment of all distal tibial fractures. It consists of:

  • Careful study of the x-rays
  • Drawing of both the fracture fragments and the desired end result (often indicated by a reversed tracing of the intact opposite tibia)
  • Consideration of intraoperative reduction techniques, including switching to open reduction in case indirect reduction is unsuccessful
  • Choice of implants

Type A (extraarticular) fractures can often be reduced by ligamentotaxis alone with indirect manipulation. Direct exposure is therefore not often necessary. The shape of the implant serves as a reduction tool. A properly contoured plate applied according to a good preoperative plan improves your chances of a good reduction.


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Implant choice and plate contouring

With MIPO plate constructs it is preferable to choose as long an implant as possible for the widest distribution of load at the fracture site.

A variety of precontoured distal tibial plates are available. If such an implant is not available, it is important to precontour the plate prior to insertion. A 3.5 or occasionally 4.5 mm standard or locking plate (LC-DCP or LCP) can often be used, but distal purchase may be compromised without a specially designed plate. For distal fractures and osteoporosis, locking head screws (LHS) may be more stable distally.

A non-contoured plate can be shaped prior to sterilisation, using a sawbone model as a template. First, determine the length of the plate from preoperative x-rays. Remember that the plate must be twisted to fit the distal tibia. As illustrated, the medial tibia distally lies closer to the sagittal plane while the shaft rotates externally above the metaphysis.

3 Preliminary reduction top

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Indirect reduction with a distractor

An appropriately positioned distractor or external fixator can be a very helpful tool for reduction, especially for length and rotation.

Where possible this should be positioned on the medial side of the leg. Distraction can be used for the open reduction and plate fixation of the fibula as first step (if not already fixed) and for the reduction of the tibia as a second stage after previous fibular stabilization.

Schanz screws are positioned in safe zones of the tibial shaft and talar neck (or the calcaneal tuberosity). In case of previously applied joint-bridging fixator, the already existing Schanz screws can be used.

4 Plate insertion top

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Insertion of the plate

Tibial length and rotation are restored indirectly with distractor or external fixation. Angulation may be approximated in the same way, but is definitively corrected by plate application.

The plate is inserted after proximal tunneling with a blunt instrument. Depending on the fracture situation, the plate is usually positioned on the anteromedial aspect of the tibia.


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Proximally, above the fracture zone, a small incision (2-3 cm) will aid plate positioning. It is important that the plate and proximal screw be centered on the tibia, particularly if locking head screws (LHS) are planned.


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Preliminary plate stabilization

Temporary fixation can be performed with K-wires through the screw holes (or inserted drill sleeves) to approximate the final plate position before screw insertion.

Once accurate position of the plate has been achieved, insert a conventional screw in one of the most distal plate holes to approximate the plate close to the bone. Alternatively, the plate can be manually pressed to the bone, allowing the insertion of a locking head screw (LHS) instead of the conventional screw.

It is crucial that the plate is positioned very close to the bone, especially at the supramalleolar level, to prevent soft-tissue irritation by the plate.

5 Applying compression top

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Applying interfragmentary compression with a lag screw

For spiral and short oblique fracture patterns (A1.1 and A1.2) that are anatomically reduced, it is possible to place a lag screw either through the plate to enhance the overall construct stability. It is possible to apply this screw in a percutaneous fashion under image intensifier control. Alternatively, depending on the fracture plane, the lag screw can be placed independent of the plate.

Note
This technique changes the construct to one of absolute stability, so a perfect
reduction must be achieved or significant delays in fracture healing will occur. See also assessment of reduction.


Compression with plate tension

For transverse type A1.3 fractures, fracture compression is achieved by applying tension with the plate, using eccentric placement of screws in non-locking holes, or an external tension device. To ensure that the opposite side of the fracture remains compressed, it is necessary to add a subtle convex prebend to the implant at the fracture level.

6 Finish plate fixation top

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Finish plate fixation

Further proximal and distal screw insertion is completed. The number and position of the screws inserted is dependent on the individual fracture pattern and bone quality. Ideally the concept of “balanced” fixation should try to be achieved.

Usually, the metaphysis requires more screws (3-5) than the diaphysis (2-3). In osteoporotic bone, the number of screws must be increased on both sides of the fracture.

Locking head screws (LHS) may improve fixation in osteoporotic bone and short periarticular segments.


Wound closure

Atraumatic skin sutures are used for closure of screw insertion wounds. Occasionally, additional deeper sutures are needed for distal and proximal incisions.

7 Final assessment top

Final assessment

X-rays at the end of the operation confirm the anatomic and fixation of the fracture (for further information see assessment of reduction).

It is important to check with imaging in both planes that a previously unrecognized split into the articular surface has not been displaced during this procedure.

Additional fixation of such a fracture line may be required.

v1.0 2008-12-03