Authors of section

Authors

Ernst Raaymakers, Inger Schipper, Rogier Simmermacher, Chris van der Werken

Executive Editors

Joseph Schatzker, Peter Trafton

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MIO - Cancellous screws

1. Principles

Introduction

Please note that impacted subcapital femoral neck fracture are relatively stable. However, undisplaced fractures are potentially unstable.

These fractures are best fixed with screws rather than the bulky sliding hip screw (DHS), which is an alternative.

No reduction is necessary.

mio cancellous screws

Cancellous screw fixation

Use two or three 7.0 mm or 7.3 mm cancellous screws. Make sure they are parallel and that the thread is in the head fragment and does not cross the fracture line.
The inferior screw should rest on the calcar. A washer may be used to stop the screw head from penetrating the bone of the greater trochanter.
These screws can be inserted open or percutaneously through stab incisions.

femoral neck fracture subcapital undisplaced or impacted

Teaching video

AO teaching video: The 7.3mm Cannulated Screw: Femoral Neck Fracture

2. Patient preparation and MIO approach

The patient is positioned supine on a conventional operating table, or on a fracture table. C-arm image intensifier control during surgery is a must.
Be gentle in transferring the patient and do not apply traction in order not to disimpact and displace the fragments.

The patient is positioned supine on a conventional operating table, or on a fracture table. C-arm image intensifier control ...

Lateral approach for closed reduction and fixation

mio cancellous screws

3. Fixation

Guide-wire insertion

The screws must be parallel. The guide wires may be inserted freehand under x-ray control to ensure they are parallel, or an aiming device may be used if available.

If using an aiming device, expose the greater trochanter through an incision just large enough for the device.

If using an aiming device with a central hole, it may be best to start by placing a wire in the center of the neck and head. The three wires for screws may then be placed through the aiming device in a triangle around the central wire, with one wire below and two above the central wire.

mio cancellous screws

Alternatively, the first wire may be placed along the inferior border of the neck, with the two superior wires then being placed parallel to the first wire.

mio cancellous screws

Determine screw length

Determine the length of the screws with the aid of the measuring device.
Choose the length of the drill and screws 5 mm shorter than the length of the guide wires.

mio cancellous screws

Insertion of the cannulated screws

Drill over the wires with a 3.6 mm cannulated drill bit. Then insert three 7.0 mm or 7.3 mm cannulated cancellous screws over the wires.
In younger patients with dense cancellous bone, the cannulated tap may be necessary to precut the thread.
A washer may be used to avoid penetration of the screw head through the thin cortex.

mio cancellous screws

4. Postoperative treatment

Elderly patients tend not to do well if kept immobilized, so early mobilization should be encouraged. Depending on the fracture configuration, strength of the bone and security of fixation, the surgeon may prefer partial or full weight bearing.

In reality, many elderly patients may not be able to comply with instructions for partial weight bearing.

In practice, it is often best overall to allow weight bearing as tolerated.

Prognosis of proximal femur fractures

After surgery the outcomes of greatest concern are:

  • mortality
  • loss of independence
  • loss of mobility
  • residual pain.

Mortality
Mortality generally occurs within the first six months after fracture; studies have shown that these rates range from 12-37%.

Predictors of higher mortality rates are patients who are:

  • older
  • male
  • have other comorbid conditions (such as cardiac failure, diabetes, and chronic air flow limitation)
  • have cognitive disorders.

Ability to return home
Besides mortality, the ability to return home is also an important outcome for patients with hip fractures. Studies have shown that as few as 50% of patients were able to return home, and that mortality rates are lower in those that do return home compared with rates in those that are transferred to nursing homes or rehabilitation centers.

Predictors of returning home include:

  • a younger age (less than 85 years)
  • ability to walk independently preoperatively
  • ability to perform activities of daily living preoperatively
  • living with another person
  • ability to walk independently at the time of discharge from the hospital.

For more information see the additional material on perioperative care in elderly hip fracture patients.