1 Principles topenlarge
By definition, type A1 fractures have no involvement of the articular surface, so accurate reduction of the joint is not required. Furthermore, this subgroup specifies two-part fractures, without comminution. Because of the simple fracture pattern, anatomical reduction and interfragmentary compression are indicated. Limited exposure for direct reduction is often necessary. This involves a longer incision than MIPO technique, but still requires preservation of soft-tissue attachments to bone.
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.
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 aid 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 and final reduction of length, alignment and rotation is achieved.
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:
- Closed reduction and joint bridging external fixation
- Definitive reconstruction after 5-10 days (wait for the apppearance of skin wrinkles)
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 topenlarge
Sequence of bone stabilization - fibula or tibia first?
In 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.
Planning for reduction and fixation
Preoperative planning is an essential part of the treatment of all distal tibial fractures. It consists of:
- Obtain good AP and lateral x-rays of both injured and uninjured side; CT if needed
- Careful study of the x-rays
- Trace AP and lateral x-rays of normal side
- Identify the individual fracture fragments
- Draw the fracture fragments, reduced, onto the normal tracing
- Consider reduction techniques
- Choose and draw in fixation implants
- Choice of surgical approach
- Prepare list of operative steps
Type A fractures can often be reduced by ligamentotaxis alone with indirect manipulation. Type A1 (two-part) fractures should be treated with absolute stability – ie, interfragmentary compression. This will require lag screw fixation and/or plate tensioning, depending upon the fracture orientation. Typically, a limited open reduction will be required, with fracture exposure for reduction and subcutaneous plate application proximally.
Proper contouring and positioning of the plate is essential for optimal reduction. Both are aided by preoperative planning.
3 Reduction topenlarge
Indirect reduction with a femoral distractor
An appropriately positioned “femoral” distractor or external fixator is usually not necessary, but it can be a useful tool for reduction. 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 tuber calcanei). In case of previously applied joint-bridging fixation, the already existing Schanz screws can be used.
Because A1 fractures are non-comminuted, absolute stability is desirable and this requires an anatomic reduction. Thus a direct reduction is usually required. At the same time, soft-tissue attachments should be preserved to the greatest extent possible.
Once visualization is adequate, the fracture can be reduced directly.
This is usually achieved with a pointed reduction clamp. Provisionally secure this reduction with one or two K-wires. Thus, the clamp can be removed for plate insertion.
Consideration of where the final position of the plate will be should guide K-wire placement. See also assessment of reduction.
4 Implant choice and plate preparation top
A variety of precontoured distal tibial plates are available. If such implants are not available, it is important to precontour the plate prior to insertion. The plate must be chosen long enough to place at least four holes proximal to the fracture (with screws in at least three of them) and distally as much fixation as possible.
A small or large fragment plate is chosen based on patient size. If locking head screws must be perpendicular to the plate, their orientation in the distal segment may not be satisfactory. Thus, conventional screws may be better in at least some distal plate holes.
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.
With ORIF of A1 distal tibia fractures, enough of the tibial surface may be exposed to aid and assess plate contouring.
5 Plate insertion and preliminary stabilization topenlarge
Insertion of the plate
The prepared plate is now inserted. Distally, the tibia has been exposed for fracture reduction. Proximally, the plate may be tunneled extraperiosteally along the tibia, under intact soft tissues.
Depending on the fracture anatomy, the plate is usually positioned on the anteromedial aspect, or seldom, on the anterior crest of the tibia.
Preliminary plate stabilization
Once accurate position of the plate has been achieved, a conventional screw is inserted 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 instead of the conventional screw. In general, 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.
Proximal plate position
The proximal end of the plate must be positioned in the center of the diaphysis. This can be done either by formal exposure of the plate end by a wider approach, or using an insert drill sleeve in the most proximal plate hole through a stab incision.
The drill sleeve can be used as a handle to manipulate the proximal end of the plate and to center it to the diaphysis. As soon as adequate position is confirmed (by palpation of the diaphysis or using fluoroscopic control), the plate can preliminarily be fixed proximally by inserting a K-wire.
6 Applying compression topenlarge
Interfragmentary compression with a lag screw
For short oblique and spiral fracture patterns (A1.1 and A1.2) the goal is to achieve perfect reduction and compression with a lag screw either through the plate or separate to it. 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-locked holes, or an external tension device. It might be advisable to insert a second and/or third screw in the distal part prior to applying compression.
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. See also assessment of reduction.
7 Finish plate fixation topenlarge
Once the preliminary fixation and reduction are satisfactory, additional screws are added for stability.
The number and position of the screws inserted depends on the specific fracture pattern. The goal is “balanced fixation”. This means roughly equivalent fixation strength in both proximal and distal segments. Usually, the metaphysis requires more screws (3-5) than the diaphysis (2-3). Cortical bone provides better screw purchase than cancellous.
In osteoporotic bone, the number of screws should be increased, particularly in the cancellous distal segment.
8 Final assessment top
X-rays at the end of the operation confirm the anatomic reduction and fixation of the fracture (see also 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.