Authors of section

Authors

Florian Gebhard, Phil Kregor, Chris Oliver

Executive Editor

Chris Colton

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MIO - lag screws

1. Introduction

General consideration

These single plane, intraarticular fractures require anatomical reduction and interfragmentary compression, sufficient to allow early joint motion. The perfection of the articular reduction is usually assessed by an open approach, but where the skills and resources are available, arthroscopically assisted reduction and percutaneous fixation may be considered. The surgeon should be prepared to find additional comminution, not evident until fracture exposure.

Note on approaches

Unless full facilities and expertise for an arthroscopic approach are available to check the closed reduction, prior to percutaneous screw insertion, the standard medial parapatellar approach is used to give an optimal view of the joint fracture reduction.

3. Reduction

General considerations

Closed reduction and internal fixation (CRIF) is used in minimally displaced, or undisplaced simple, medial sagittal, partial articular fractures.

Preliminary reduction
As simple, medial sagittal, partial articular fractures usually result from a varus force, the application of a valgus stress may reduce the fracture. If valgus stress alone is not sufficient, arthroscopy may be helpful to assess the accuracy of the reduction.

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Temporary K-wire placement

Under image intensifier control, make a stab incision over the medial aspect of the injured condyle and insert a temporary K-wire, to hold the reduction.

Make sure, that the K-wire does not conflict with the planned screw tracks.

Check of reduction
Check the reduction in two planes using the image intensifier.

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4. Insertion of lag screws

General consideration

In general, the screws are inserted at points along the midshaft axis of the femur (dotted line). The area distal to the Blumensaat’s intercondylar roof line must be avoided, in order not to violate the notch. In addition, the area of the medial knee recess should be avoided.

If you need to insert a screw in the area distal to the Blumensaat’s intercondylar roof line, direct the screw anteriorly, in order to avoid the intercondylar notch.

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Drill screw hole

Make a small 1.2 cm incision.

Create a pilot hole using a 3.2 mm drill bit in the direction of the eventual screw insertion.

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Determine appropriate screw length

Insert a depth gauge into the hole, to determine the appropriate screw length. Generally, a screw is chosen which is 5-10 mm short of the lateral cortex.

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Tapping

Remove the depth gauge and tap for the 6.5 mm cancellous bone screw under image intensifier control. In all but the densest cancellous bone of young athletes, tap only the near fragment – the screw itself will normally create its own thread in the cancellous bone of the far fragment

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Screw insertion

Insert the 6.5 mm partially threaded cancellous bone screw and fully tighten. In the case illustrated, the partially threaded screw will have 32 mm of thread, as opposed to 16 mm of thread.

Note: a washer may be used, particularly in osteoporotic patients.

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Additional screw insertion

Insert 1 or 2 additional screws in a similar manner, and remove the K-wire.

partial articular fracture medial condyle sagittal simple

5. Aftercare following screw (and plate) fixation of partial articular fractures

Introduction
Impediments to the restoration of full knee function after distal femoral fracture are fibrosis and adhesion of injured soft tissues around the metaphyseal fracture zone, joint capsular scarring, intra-articular adhesions and muscle weakness.

Continuous passive motion is a low load method of restoring movement and is a useful tool n the early post operative phase. It must be used in combination with muscle strengthening programs. With stable fracture fixation, the surgeon and the physical therapy staff will design an individual program of progressive rehabilitation for each patient.

The regimens suggested here are for guidance only and not to be regarded as proscriptive.

Functional treatment
Unless there are other injuries, or complications, joint mobilization may be started immediately postoperatively. Both active and passive motion of the knee and hip can be initiated immediately postoperatively. Emphasis should be placed on quadriceps strengthening and straight leg raises. Static cycling without load, as well as firm passive range of motion exercises of the knee, allow the patient to regain optimal range of motion.

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Weight bearing
Touch-down weight bearing (10-15 kg) may be started immediately with crutches, or a walker. This will be continued for 6-8 weeks postoperatively. After that, touch-down weight bearing progresses to full weight bearing gradually over a period of the next 2 to 3 weeks. In general, patients are full weight bearing without devices (e.g., cane) by 10-12 weeks.

Follow up
Wound healing should be assessed at 2 to 3 weeks postoperatively. Subsequently 6 week, 12 week, 6 month, and 12 month follow-ups are usually made. Serial x-rays allow the surgeon to assess the healing of the fracture.

Implant removal
Implant removal is not essential, unless there are implant-related symptoms after consolidation.

Thrombo-embolic prophylaxis
Consideration should be given to thrombo-embolic prophylaxis, according to local treatment guidelines.