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Fracture Healing

 

 

Introduction:  

Healing of bone fracture related to a  biological procedure that 

results in different stages. At first,  Haematoma and a blood clot

formed and inflammatory cells accumulation as well as clean out debris at the

fracture site. Which is followed by  formation of a soft callus made of organic

matrix like collagen, and gradually hardens into a hard callus which 

forms  woven bone.With a period of time, remodeling occurs where the 

hard callus is replaced by mature lamellar bone, restoring the bone's 

shape and strength and reappearance of medullary cavity. Adequate 

nutritional supports, immobilization, and sometimes surgical 

intervention are essential for  fracture healing effectively and timely.

 

•Primary Healing-(Direct Union)

 

•Secondary Healing(Callus Formation)

 

•Primary Healing

 

Bone healing occur without callus formation

 

Fracture gaps are invaded by new capillaries and osteoprogenitor cells.

new bone is laid down in the exposed surface.

 

Gap healing –when gap is more than 200 µm, at first woven bone formation 

then remodeled into lamellar bone.

 

Contact Healing –When gap is less than 200 µm, Direct lamellar bone formed.

Example- Impacted fracture in cancelous bone,

 

 

 

•Secondary Healing(Callus Formation)

 

•Tissue Destruction and hematoma 

 formation

•Inflammation and cellular proliferation

•Callus Formation (soft callus formation and hard callus formation )

& mineralization

•Consolidation

•Remodeling

 

 

•Tissue Destruction and hematoma formation- 

Vessels are torn and haematoma formed in  and around the Fracture site.

•Inflammation and cellular proliferation:

 

With in 8 hours ,acute inflammatory reaction and migration  

of inflammatory cells and proliferation of mesenchymal steam cells,

The clotted haematoma is reabsorbed slowly.

 

 

Callus Formation:  

The differentiating steam cells provide chondrogenic and osteogenic cells and 

with right conditions they will start forming bone also cartilage(in some case),

Osteoclast also appeared, and 

 

A thick cellular mass with its islands of immature

bone forms splints on the periosteal and  endosteal surface—called callus.

at about 4 weeks fracture ‘unites’.

 

 

 

•Consolidation :

 Woven bone is transformed into lamellar bone with continuous activity of 

osteoblast and  osteoclast, Osteoclast  burrow through debris at fracture site 

and osteoblast laid new bone behind it and also fill the gap simultaneously. 

fracture covered by a cuff of solid bone.

 

Remodeling:

 over a period of times this crude ‘weld’ reshaped.

unwanted buttresses curved away and medullary cavity reformed with 

continuous bone resorption and bone formation 

 

 

•Union- 

Incomplete Repair, callus is calcified, mild tender, attempt angulation 

painful.

•Consolidation-

Complete Repair,calcified callus is ossified, non tender, attempt 

angulation not painful.

•Nonunion-

Normal Process of bone healing thwarted and bone fails to Unite.

 

 

Factors Influencing Bone Healing

 

 

Systemic factors :

Age ,

Activity,

Nutrition,

Hormonal factors,

Disease,

Vitamin deficiency,

Drugs

Habits,

Systemic growth factors,

Environmental factors,

CNS injury 

 

 

Local factors:

•A.-factors independent of type of injury,

 treatment, complication 

 •B. Factors  depends on injury, 

 •C. Treatment factors, 

 •D. Factors associated with complication

 

 

A.-Factors independent of type of injury, 

treatment, Complication- 

 

Bone type, 

Abnormal or diseased bone

 

B. Factors  depends on injury—

 

Local Damage -velocity of trauma,

Fracture comminution, compound fracture, 

Low vitamin K, 

Disruption of vascular supply,  Type of bone fracture, 

Bone loss, 

Soft tissue interposition.

 

•C. Treatment factors—

 

•Surgical trauma,

•Implant induced alteration of blood flow,

•Degree of rigidity and fixation,

•Load induced deformity of bone and soft tissue,

•Extent of contact of fragments,

•Post traumatic osteogenesis

 

 

•D. Factors associated with complication­—

 

•Infection,

•Venous stasis,

•Metal allergy.

 

 

•Factors affects Negatively in Bone Healing

 

•A. Tobacco Smoking—

 

•Smoking,

•Previous smoking,

•And smokeless tobacco - delay the healing process,

•Even Healing may require double time than normal.

 

 

•B. NSAID-                                

 •Cyclooxygenase 1, inhibitors             

 •Cyclooxygenase 2, inhibitors

 •Ibuprofen,

 

C . Antibiotics -  Fluoroquinolone

 

D. Co morbidity

 

 

 

 Stimulation of Fracture Healing:

 

 

1. Autologous bone graft.

2. Bone graft substitute.

3. Electrical and ultrasound  stimulation

 

 

1.Autologous bone graft:   

 

When bone harvested from won site, It has 3 important functions-

i. Osteoconduction,

ii. Osteoinduction,

iii. Cellular osteogenesis. 

 

•BONE GRAFT

Introduction: 

•A Surgical procedure in which Harvesting of bone from donor site to recipient site.

Type:

•Autogeneous

•Allogeneous

•Heterogeneous

 

 

 Function : 

•Osteoinduction

•Osteoconduction

•Osteogenesis

 

Indication: 

           •Fracture Healing,

•Bone Defects,

•Non-Union Fractures,

•Corrective Osteotomy,

 •Revision Surgery

 

 

 •Common sites  -

Local bone remove during arthrodesis,

Iliac crest, ( 2nd most common, but some side effects- pain, neuroma, fracture, 

heterotrophic bone formation,), 

Fibula,

Rib,

Tibia,

Femoral bone marrow harvesting,

  (RIA synthesis- decompression, reduce fat embolism )

 

 

 Complication: 

 

Infection,        

Graft Failure,

Pain and Discomfort,

Bleeding,

Nerve or Blood Vessel Damage,

Graft Rejection,

Allergic Reaction,

Graft  Resorption

 

 

2.Bone Graft Substitute:

 Five major categories—

            i.  Allograft base

 ii  Growth factor based,

iii. Cellular based,

iv. Ceramic base

 v. Polymer base.

 

 

•i Allograft base—

When taken from same species, it may be –

•Freeze dry,

•Irradiated,(provide structural support)

•Decalcified (DBM)—

 

•ii. Growth factor based—

 BMP, TGF

 

•iii. Cellular Based- 

•Autologous bone marrow,

•Embryonic stem cells,

•Bone Marrow stem cells,

 

 

•iv. Ceramic based :

•Calcium sulphate,

              •Calcium Phosphate,

(Synthetic hydroxyapatite, available as paste, granule,solid, putty)

•Bioactive glass,-Silicate base glass.

 

•v. Polymer Based- 

•Natural,

•Synthetic,

•Biodagredable,( PGA, PLGA)

•Nonbiodegradable

 

 

•3. Ultrasound and electrical stimulation—

 

Low voltage electricity, 

USG may stimulate bone healing.

 

 

 

Conclusion:

      Bone fracture healing results in the stablistment  of the bone's structural stability and function with a complex biological process. A good healing depends on  proper alignment, fixation or holding the fracture fragments, and adequate blood supply. Finally, the remodeled bone regains its strength and capability to allow normal mechanical stresses..