Insertion of a screw-plate
using a minimal lateral access technique

Frédéric LAUDE
Hôpital de la Pitié,75013 Paris - Fr
Cliniques des Lilas, 93260 Les Lilas - Fr
flaude@maitrise-orthop.com

The conventional procedure for the insertion of a lateral screw-plate involves elevating the vastus lateralis and extensively exposing the proximal part of the femur.
It was felt that by using a minimal access technique, the internal fixation of a pertrochanteric fracture using a sliding screw-plate could be performed much less invasively, without touching the fracture site, and without detaching the vastus lateralis.

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PRINCIPLE

The screw entry site of a lateral plate on the femoral shaft is situated about 2-3 cm below the crest on which the vastus lateralis originates. This distance is ample for the insertion of the targeting device, without any need for detaching the vastus lateralis from its trochanteric origin. The continuity between the vastus lateralis and the gluteus medius is preserved. All that needs to be done is to detach the vastus lateralis from the femoral shaft, and to reflect it anteriorly. Since the first 2 cm of the vastus are not affected by the procedure, the skin incision used in the past to expose that part of the muscle is not required for this procedure.

TECHNIQUE

Reduction is performed on a fracture table, with the patient positioned supine. Reduction is checked with the image intensifier. In almost all cases, rotation, adduction, and traction will enable the surgeon to obtain good reduction of the fracture fragments.

The skin incision is modified, to suit the minimal access nature of the technique. Proximally, it starts at a point where the axis of the femoral neck intersects with the skin of the thigh (Fig. 1). The corresponding landmark is readily established during reduction under image intensifier control, by placing a long non-sterile pin on the skin to coincide with the axis of the femoral neck. The landmarks are drawn on the skin with a waterproof marking pen. The incision extends distally in a straight line for a distance of 4-5 cm. After closure of the incision at the end of the procedure, the line will be over the holes in the shaft plate (Fig. 6).

Fig 1: Preoperative marking of the incisional line (red = conventional; green = minimal access)

This minimal access may appear tight for some of the manoeuvres involved. However, the skin of elderly subjects has so much give that the use of Farabeuf retractors along the incision will give much better exposure than would be expected from the size of the incision.

The fascia lata is incised longitudinally. Both proximally and distally, this incision is extended beyond the limits of the skin incision.

A Beckmann retractor is inserted against the fascia lata posteriorly and the vastus lateralis anteriorly.

The posterior part of the superficial fascia of the vastus lateralis is incised longitudinally, in customary fashion. However, the vastus is not detached from its origin at the base of the greater trochanter. The approach used in this technique is not through the vastus lateralis.

The vastus is lifted with a Lambotte elevator. The self-retaining Beckmann retractor is placed underneath the vastus lateralis anteriorly and the tensor fasciae latae posteriorly.

In this way, the shaft is exposed over a distance of 6-7 cm.

The targeting device provided with the plate is placed against the shaft in customary fashion (Fig. 2).

Fig 2: Insertion of the targeting device

It must be possible to slide the targeting device under the vastus lateralis, to wedge it in the upper part between the vastus and the femoral shaft. Not all targeting devices are suitable for this technique: Some are too bulky to slide readily under the muscle. It is best to have the targeting device handle as low as possible on the metal part that goes against the shaft. The targeting device is often right against the limit of the skin incision, and considerable pressure will need to be exerted in order to position it correctly. Spikes on the underside of the targeting device are a useful feature. The device is correctly inserted underneath the vastus; next, it is very firmly pushed in a proximal direction. This will make the device seat itself in the correct position, and will, almost always, produce correct alignment with the desired pin entry site (Fig. 3). If a radiolucent targeting device with a slightly inclined handle is used, the correct positioning of the targeting device and of the pin can be verified straight away.

Fig 3 : Features of the ideal targeting device

After the placing of the pin, the procedure is continued in conventional fashion. The skin at the proximal end of the incision is held out of the way with a retractor when the drill is inserted.

The axial screw must be inserted with an extension (Fig. 4).

Fig 4: The screw and extension have been inserted. The extension exits right against the proximal margin of the incision

). The plate is then slipped onto the extension. Usually, the plate will appear far too long to be accommodated by the skin incision. When it is introduced along the extension, it will, as a rule, be lying on the skin beyond the distal margin of the incision (Fig. 5).

Fig 5: The plate slides along the extension and "dives" into the incision.

However, the 135° angle between the barrel and the plate will make the plate readily "dive" into the incision. The only assistance needed is spreading of the fascia lata and the vastus lateralis as the plate goes in.

Once the plate is against the femoral shaft, all that remains to be done is the insertion of the shaft screws. This is straightforward, since the incision is very low on the femur, and the plate can be readily seen (Fig. 6). At this stage, the coincidence of the future scar line and the line of plate screws can also be verified.

Fig 6 : Once the plate is against the shaft, all that should be visible is the plate holes. Screw insertion is straightforward.

CONCLUSION

With a little practice, this technique can be readily mastered. It provides for greater ease of insertion of lateral sliding screw-plates.

The skin incision is minimal (Fig. 7).

Fig 7 : Final appearance of the scar

The approach involves little tissue destruction, and causes less bleeding than do conventional techniques. Operative time is reduced.

The procedure is performed without exposing the fracture site.

The continuity between the vastus lateralis and the gluteus medius is preserved. It is obvious that secondary displacements of the trochanter are less likely to occur.

Some instruments for plate insertion may need to be modified. Radiolucent targeting devices would make the surgeon's life easier.