.

Fracture fixation devices with threaded screw holes, which allow screws to thread to the plate and function as fixed angle device.

Any plate that allows the insertion of fixed angle or angular stable screws or pegs can be used as a locking plate.

Follow the principle of ext.fixator INTERNAL FIXATOR Stability is maintained at angular stable

screw plate interface. Single beam construct. Pullout strength of locking screws higher

than that of conv. screws

Has a combination hole whereby conventional cortical screws can be applied to achieve compression or locking head screws can be applied for angular stability.

No loss of primary or secondary # reduction.

No necrosis (stress shielding) under the plate.

Preservation of periosteal blood supply decrease in infection.

Increased stability, less soft tissue dissection enhanced # healing

Strain at the # site is optimized so secondary bone healing with callus formation.

Allows the use of unicortical screws Higher resistance to infection, faster union

and lower refractures.

More expansive More difficult to use to help achieve an

adequate reduction.[speciality p] Do not improve reduction and cannot help a

poorly reduced # fracture to heal.

Fractures associated with higher risk of loss of reduction and plate or screw failure.

Unsolved or problem fractures1. Comm. Intraarticular # 2. Short segment periarticular # 3. Osteopenic bone #.

According to mode of application of the plate.

All indications are based on this four principles.

1. Compression P2. Neutralisation P3. Bridging P4. Combination P

Mode of application compression or neutralization principle.

Compression P osteoporotic forearm # Neutralisation P osteoporotic ankle #. [first

lag then lock].

Mode of application bridging or combination principle.

Proximal & distal humerus, distal radius, proximal tibia.

.Applied , according to Combination principle.Lag screws for articular fixation, locking head

screws for metaphyseal bridging. Distal femur & tibia.

4. Comminuted shaft fractures mode of application bridging principle

[locked internal fixator].Shaft of femur, tibia, humerus.

Using locked internal fixator technique for simple # that requires interfragmental compression.

Using minimally invasive percutaneous plate fixation tech for simple fractures [violates concept of # gap width in relation to strain nonunion.

Using locking internal fixator tech for fixing displaced intraarticular # [Malunion, arthritis].

Relatively C.I for # which can be satisfactorily fixed with conventional plates.

Secondary loss of reduction with varus collapse as result of inadequate screw length and inappropriate fixation of locking head screws in plates.

Failure of interface between locking head screws and threaded plate holes occurs if screws are inserted imperfect angle and torque limiting screw drivers not used.

Increased strain in a construct with too much stiffness and exposure to high rotational forces will lead either to breakage of plate in D.C part of combihole which is the weakest part of the construct or more rarely failure at screw plate interface with breakage of screws.

Locking screws cannot recede back wards as a conventional screws can.So if longer screws are used in the head part of the periarticular # ,chance of protrusion of the screws in to the Jt.

Formal preop planning is a must.1. Sequence of screw placement2. Length of screw3. Position of plate4. Surgical approach.• Help to reduce the guess work and

increase the technical success

Correct positioning of the Pt esp, in MIPPO technique.

Surgeon should also have preop plan for # reduction.

L.P offers minimal opportunity for screw angulation. [> 5* angulation failure.

Screw should be perfectly lined lined up with the axis of the screw threads in the plates. [otherwise cross threading or cold welding will occurs]

Malaligned screw threads loose screws and loss of reduction.

In order to achieve a large area of stress distribution on the plate ,at least three or four holes should be left empty, at the level of the #.]

Unicortical Screws should be of optimal length as short s. failure, long s. push off from the far cortex thus destroying the tapped, near cortex.

Bicortical or unicortical self drilling / Self tapping or self taping Pullout resistance of unicortical locking

screws is almost identical to that of similar diameter bicortical conventional screws and about 70% of bicortical L.S.

Locking screw heads are less likely to break since difference between core diameter of the screw shaft head is much smaller than conv.S.

Nevertheless they can break in case of chronic instability and increased strain as a result of rotational forces.

Usage of torque limiting screw device so threads cannot be stripped or over-tightened. Even then happens in MIPPO due to difficulty in judging the orientation without direct visualization.

Purchase of the screw in the bone cannot be felt, L.S always feel tight.

Two factors are essential in decision making;

1. Quality of the cortical bone2. Extent of rotational forces applied to the

cortical bone.

In a good quality cortical bone, the working length of a Unicortical screw provides sufficient pullout strength.

In metaphyseal and osteoporotic ,due to thin cortex always better to use bicortical screws.

As a general rule self drilling / self tapping screws are used in a unicortical fashion , for MIPPO technique.

Self drilling screws [sharp tips] can cause neurovascular damage or soft tissue damage across the far cortex.

Bicortical screws should be used for # which are exposed to high rotational forces like SOH.

For long bone comminuted #, B.P used must be of longer length with fewer screws to used.

For periarticular # few screws are needed for diaphysis and more screws are needed for articular surface recon.

In general length of the plate should be two times the length of the fracture zone.

Screws should be evenly spread and ideally there should be one empty hole between each pair of holes filled with screws.

To avoid local stress conc, 3 / 4 holes should be left empty at the level of #.

Locking plates, particularly the specialized so-called all-locking plates, require an approach to fracture reduction that is completely different from what is already practiced.

• One should consider initially using combination plates, that allows traditional reduction tech.