Physiology and biomechanics of fracture healing with a special reference to non invasive biological methods.

Physiology and

Biomechanics and pathophysiology of fracture healing with a special reference to non invasive biological methods.

Dr L.Prakash M.S., MCh. (liverpool)

Man doesnt heal fracturesNature does

What happens if you dont treat fractures??What happens to animals with fractures??When was the first metal put in the human body?Why occasionaly fractures dont heal despite multiple surgeries?Is there any absolute indication for internal fixation??These and other Questions often plague us orthopaedic surgeons

Questions Questions QuestionsWild animals in the jungles dont go to a bone setter or an orthopaedic surgeon. Yet their fractures heal most often.Animals with fractures know that the broken limb is to be kept immobile until pain subsides.They then gradually return to function after the fracture heals.

An untreated horse, back to walking in 2 months

Dogs dont go to orthopaedic surgeons

This is an Irish setter with a bad malunion

There he is after six months

Untreated fractures invariably heal

It may heal with shortening

It may heal with over riding

But it heals neverthelesss

When was the first metal implanted into the human bone????

An Egyptian mummy with a screw like device transfixing the knee, is the oldest known case of a metal implant in the bone.

The mummy storyIn 1971, the Rosicrucian Museum in California acquired a sealed ancient Egyptian coffin containing the well-preserved mummy of a high status Egyptian male. More than two decades later, a team of scientists made a shocking discovery the mummy displayed evidence of an advanced surgical procedure carried out nearly 2,600 years ago. Inside the mummys left knee was a 9-inch metal orthopaedic pin that had been inserted with such advanced biomechanical principles, that initially scientists could not distinguish it from a modern-day procedure

So man has been trying to play god for over two thousand years!!

And now he thinks that he is probably better than GOD

But the worst by nature can certainly not compete with the worst by man

But the worst by nature can certainly not compete with the worst by man

But the worst by nature can certainly not compete with the worst by man

But the worst by nature can certainly not compete with the worst by man

But the worst by nature can certainly not compete with the worst by man

To treat fractures properly, we need to understandBiology of normal fracture healingBlood supply to the bone Role of immobilisationRole of micromotionRole of mobilisationThe difference between ANATOMICAL and FUNCTIONAL reduction of a fracture.

Blood supply to the bone Is either medullary or corticalNutrient artery perfuses the medullaPeriosteal vessels supply cortical bone.

When a fracture occurs:

Periosteum is tornMedullary integrity is disturbed.A fracture haematoma collects and stops when the internal pressure equals systolic BP

Now starts the fracture healing

Haematoma resolutionDeposition of soft callusMaturation of the callusCalcification or hard callusConsolidationRemodelling

This pattern is universal with all fractures

All fractures more or less follows the rule of three.

No fracture heals before three weeksAdults take twice the time as adolescentsChildren take half the time as adolescentsLower limb fractures take twice the time as upper limb fracturesOpen fractures take twice or more time as closed fractures.

Thus all fractures will unite if you give it sufficient time.

The only question is whether it will unite in an anatomical position or not.

It is essential to know the differenceUnion in anatomical position versus healing in functional position.

Anatomical position:

No overridingNo rotationNo angulationAccurate repositioning of the fractured ends.

Functional positionIrrespective of what the X-ray shows, the person is able to use the limb to full function after fracture healing

Fracture haematoma is like colostrum for a new born.

Periostal integrity is essential for microvascular transport of callus and other factors stimulating bone healingWe surgeons open the fracture converting a simple one to COMPOUND.We then suck away all the valuable haematoma.

What good would a haematoma do inside a suction bottle??

We then cut the periosteum, thereby disturbing the blood supply. We dill holes right across disturbing the medullary supply

Else we ream the medulla totally removing the valuable marrow

IS THERE ANY consequence OTHER THAN THIS??

Or this

Or these

And these

Or more of these

In surgically fixing a fracture we DELAY natures attempts at fracture healing

We deliberately convert a simple (closed) fracture to compound (open) fracture

All internally fixed fractures will certainly heal SLOWER than the one left alone

An infected non union for a surgeon is just a statisticBut for the patient it is:A lost jobA missed examinationA ruined careerA groom or boy being denied marriageThe whole household in debts for yearsMisery misery miseryFor him it is 100% disaster, multiple surgeries, prolonged morbidity, and Hell of a life

A fractured limb can be encased in a rigid plaster but the bone inside cannot.

A fractured limb can be encased in a rigid plaster but the bone inside cannot.

Micromotion at the fracture site has a very important role in bone healing.

Minute movements of the fracture ends causes callus to be thrown at the site

A cyclically loaded rotatory micro-motion will cause lot of callus but the ends dont get a chance to unite. This causes the elephant foot non union.

An angular micromotion produces atrophic of horse hoof non union

Minimal compression distraction produces healthy callus!!

A nail providing this situation clearly throws up a lot of healthy callus

Lanyon and Rubin ( 1984) demonstrated that cyclic axial loading increases callus formation and maintained good bone mass.

Woolf and Wright (1981) and Goodship & Kenwright (1985) demonstrated shortened fracture healing times in animals, with intermittent cyclic axial dynamization.

So it can be logically concluded that fractures can be treated by :

Rigid immobilisation with compression or locking plates.Semi rigid immobilization with nails, made more rigid by locking.Non rigid immobilisation by plasters or splintsRigid immobilisation by external fixatorsDynamic immobilisation by traction or Flexible external fixators.

Rigid versus Non rigid immobilisation

The Synthes group led by Muller, Algover, and Willeneggar, advocated compression plating and described PRIMARY BONE HEALING

Primary bone healing

No external callus is visiblePatient returns to function immediately

Primary bone healingX-rays look FantasticBut: There is no way to tell when the fracture has united.

Primary bone healing

In many cases the fracture has fallen apart when the plate was removed after eight to nine months.

This prompted the Synthes group to issued a guideline that the plate should not be removed before 18 to 24 months or never at all

What actually happens with COMPRESSION PLATING?

The plate assumes the function of the bone, bypassing the forces, which now travel through it.

Surgical trauma, periosteal stripping and medullary drilling compromises the vascularity.

All plated fractures heal considerably slower than conservative

What actually happens with COMPRESSION PLATING?

There is a constant race between bone healing and implant stresses.If the bone heals first, as it happens in majority of cases, all is well!! Else the plate will break!!

What actually happens with Intramedullary unlocked nails??Advantage of Good vertical compression without locking.Gives good resistance in lateral shifts and angular stresses

BUT BUT BUT.

Reaming of the medulla screws up the blood supply

Gives poor resistance to rotatory stresses.

What actually happens with Intramedullary locked nails??

Good compression and rigid fixation possible

Distinct disadvantage is that compressive micromotion is lost.

May need dynamisation at a later stage by removal of some locking screws.

What happens with rigid external fixators, both static and dynamic??

Uniaxial fixators have a very high shear stiffness in the plane of pins but low in 90 degree shift.

Biaxial fixators have high shear stiffness in both lateral bending and torsion.

During linear compression of these fixators, plastic deformation of the pins is usually observed.

The magic of original Ilizarov

Original

Original

Original

This is not an Ilizarov assembly

See the Shanz pins sticking out!!!

This is not an Ilizarov assembly

See the Shanz pins sticking out!!!

This is not an Ilizarov assembly

See the Shanz pins sticking out!!!

This is not an Ilizarov assembly either!!!

In my opinion there are only three MAGIC COMPONENTS in IlizarovTensioning of wires

Corticotomy

Controlled distraction

A 1.8 mm K wire, tensioned at 80 kg is stronger than a 7mm Stienman pin and yet inherently elastic compared to a stiff pin.

Originally G A Ilizarov never used anything except pins. Thin pins, thicker pins, but all pins capable of being tensioned.

By substituting Shanz screws for K-wires, we loose the Magical advantage of INHERENT DYNAMISM

A shanz pin will exhibit ductile behaviour, and axial loading often produces pin deformation

Corticotomy is just that...Cutting the cortex alone without interfering with the medulla

Technique

The third magic of LlizarovControlled Distraction, both for bone transport and elongation.

Fortunately, this is something everyone knows and follows.

If we do not respect the original concepts of the designer, the results will decidedly be inferior!!

So what can we conclude from this talk?

Have I advocated a complete ban on internal fixations in fractures??

Do I recommend conservative management in all cases??

Do I recommend Ilizarov in most trauma cases?

No,

No,

No

Internal fixations do have a role, but it is limited

Ilizarov fixations too should be handled similarly and the correct patient and fracture is to be chosen. But please avoid stiff Shanz pins in the Ilizarov system.

In intraarticular fractures with or without dislocation Ilizarov gives distinctly better results. A ligamentotaxis usually restores the joint.A good percentage of fractures can well be treated conservatively.

Example of Ligamentotaxis

We must not forget skeletal traction, Fisk traction, gravity methods, plaster applications, and splints!! These too have an important role in selected cases.

And in conclusion:

Hippocrates has said it .. Do no harm

Dont fight nature, assist natural processes.

Think very carefully before converting any simple fracture into a compound fracture

Thank You