role of mesenchyme stem cells in the chondro-osseous graft ...page 1 of 7 research study icensee...

of 7

Research study

Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY)

For citation purposes: Kummoona R. Role of mesenchyme stem cells in the chondro-osseous graft reconstruction of temporomandibular joint for continuous growth of the mandible and midface. Annals of Oral & Maxillofacial Surgery 2013 Feb 01;1(1):2. Co

mpe

ting

inte

rest

s: n

one

decl

ared

. Con

flict

of i

nter

ests

: non

e de

clar

ed.

All

auth

ors

cont

ribut

ed to

con

cepti

on a

nd d

esig

n, m

anus

crip

t pre

para

tion,

read

and

app

rove

d th

e fin

al m

anus

crip

t.A

ll au

thor

s ab

ide

by th

e A

ssoc

iatio

n fo

r Med

ical

Eth

ics

(AM

E) e

thic

al ru

les

of d

iscl

osur

e.

Aes

thet

ic S

urge

ry &

Med

icin

e

Role of mesenchyme stem cells in the chondro-osseous graft reconstruction of temporomandibular joint for

continuous growth of the mandible and midfaceR Kummoona*

AbstractIntroductionThis study included 37 children who were treated by reconstruction of the temporomandibular joint (TMJ) by chondro-osseous graft from the iliac crest. The role of granular mes-enchyme stem cells of the graft is to simulate normal condyle for continu-ous growth; it is also involved in re-pair and remodelling of the condyle, as shown by experimental studies conducted on rabbits and by clinical application. This technique has been used in treatment of ankylosis of the TMJ, hemifacial microsomia and trau-matic hypoplasia of the condyle. The total number of cases was 37 chil-dren: 26 cases with ankylosis of the TMJ (10 girls and 16 boys), 10 chil-dren with hemifacial microsomia or first arch dysplasia syndrome (4 girls and 6 boys) and 1 girl with traumatic hypoplasia of the condyle. Their age was between 4 and 13 years (mean, 8.5 years). Follow-up period was be-tween 3 and 10 years; all cases were treated in the Maxillofacial Unit, Surgical Specialty Hospital, Medical City, Baghdad, Iraq. The aim of this research is to discuss the role of mes-enchyme stem cells of the chondro-osseous graft reconstruction of the TMJ for continuous growth of the mandible and midface.Materials and methodsAnimal experiments were perform-ed on six rabbits (age, 3 months);

TMJ reconstruction was done after excision of the condyle. Three months later, the animals were killed and po-st-mortem studies macroscopically showed that the chondro-osseous graft was united, remodelled and healed with the ramus; the head sh-ape was similar to that of the control. ResultsThe graft was fixed by a stainless ste-el wire of 0.5 mm and did not show any corrosive property, infection or resorbtion of the bone surroundi-ng the wire or changes in the col-our of the wire. Microscopically, there were four distinct zones or layers; the first layer, consisting of fibrocartilage layer, was thick due to functional demand of hard mastic-atory processes; the second prolifer-ative layer showed several layers of active round granular mesenchy-me stem cells; the third layer showed hypertrophic chondrocyte conversion into osteocyte and the cartilage arranged in a multidirect-ional fashion due to environmental changes in masticatory function requirements instead of vertical columnar growth pattern as in iliac crest as a weight bearing bone; and the fourth layer was an os-teoid layer with bone marrow spaces in between.ConclusionThis valuable research shows the ability of the chondroosseous graft to be a good substitute of the condyle with regard to both growth and func-tion in children.

IntroductionSurgery of the temporomandibular joint (TMJ) is usually difficult in the management of diseases such as

ankylosis, mild hemifacial microso-mia or hypoplasia of the condyle. It has always been a challenge to maxil-lofacial surgeons, particularly in the West for the last four decades, as they do not encounter many such cases.

Many attempts have been made in the past for biological reconstruction of the TMJ by autogenous tissue-like metatarsal phalangeal bone graft, sterno-clavicular head, bone graft from iliac crest or rib graft for the re-construction of the condyle. All these attempts have failed to show a con-tinuous growth in the condyle.

The application of the costo-chondral graft by Sir Harold Gilles, introduced in early last century, on patients by Kennet (1973) and the experimental studies of costo-chon-dral graft on iris monkeys by Poswil-lo (1974) made great advances in the usage of this graft for TMJ recon-struction. Over the last 4 decades, it has become the only popular tech-nique to be practiced.

The TMJ is unique as it is the only joint with two compartments with an inter-articular disc in between; it has no role in the growth of the condyle, but it acts as a protector to the head of the condyle. It also plays a role in the sliding movement, for maintain-ing lubrication of the condyle and for the protection of the head of the con-dyle during masticatory function. It helps in advancing the condyle dur-ing mouth opening with the lateral pterygoid muscle.

TMJ development begins later dur-ing the embryonic stage, after de-velopment of other joints has been completed. In the lower compart-ment, the head of the condyle grows in an upward direction to establish

* Corresponding authorE-mail: [email protected]; [email protected]

Emeritus Professor of Maxillofacial Surgery, Iraqi Board for Medical Specializations, Medical City, BO Pox 5116, Bab Al Moa dam, Baghdad, Iraq

of 7

Research study


For citation purposes: Kummoona R. Role of mesenchyme stem cells in the chondro-osseous graft reconstruction of temporomandibular joint for continuous growth of the mandible and midface. Annals of Oral & Maxillofacial Surgery 2013 Feb 01;1(1):2. Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

. A

ll au

thor

s co

ntrib

uted

to c

once

ption

and

des

ign,

man

uscr

ipt p

repa

ratio

n, re

ad a

nd a

ppro

ved

the

final

man

uscr

ipt.

All

auth

ors

abid

e by

the

Ass

ocia

tion

for M

edic

al E

thic

s (A

ME)

eth

ical

rule

s of

dis

clos

ure.

and midface and to continue growth, remodelling and repair.

A total number of 37 cases were included: 26 children including 10 girls and 16 boys with ankylosis of the TMJ, 10 cases including 4 females and 6 males with first arch dyspla-sia or hemifacial microsomia, and 1 female with traumatic hypoplasia. Their ages ranged between 4 and 13 years (mean 8.5 years), and the fol-low-up time ranged between 3 and 6 years.

All cases were treated in the Maxil-lofacial Unit, Surgical Specialty Hos-pital Medical City, Baghdad, Iraq.

Experimental studiesExperimental studies were con-ducted on eight young rabbits (age, 3 months; approximately the same weight of 1.5 kg) and two animals were used as a control (1 left and 1 right). In this experiment, the rab-bits were divided into two groups; each group had four rabbits. The TMJ rabbits were subjected to me-niscectomy and codylectomy. Sur-gery was performed via a curve incision, extending from the outer canthus of the eye to the pre-au-ricular region, and the zygoma was palpated as a landmark for localiza-tion of the TMJ. A piece of full thick-ness bi-cortical bone segment of the iliac crest graft, measuring 1.8 cm, with a cartilage cap was fixed to the outer surface of the ascend-ing ramus, and before that, de-cor-tication of the ramus and graft was done before fixation of the graft by a soft stainless steel wire of 0.5 mm. The graft was fitted to the glenoid fossa before fixation of the graft (Figure 1A).

Surgical procedure was performed under ketamine hydrochloride seda-tion (Vetalar Ketamine HCL, Astra pin, Germany) of 50 mg/kg of body weight IM with infiltration of TMJ by a local anaesthetic agent, Lingo spam (lignocaine hydrochloride 2% with adrenaline 1/80000, St. Maur, France) (Figure 1A).

the short body featuring antegonial notch in the lower border of the man-dible; this was also considered as an important clinical sign of TMJ anky-losis.

Experimental studies in rabbit TMJ reconstruction by chondro-os-seous graft proved the presence of an active layer of mesenchyme stem cells in the graft. These mesenchyme stem cells differentiate to form chon-drocyte and osteocyte; the chondro-cyte cells converted cartilage cells, by series of differentiations, to hy-pertrophic chondrocyte to osteo-blast. These stem cells are involved in bone formation, maintaining con-tinuous growth of the TMJ and in-volved in repair and remodelling of the joints.

The aim of this research is to dem-onstrate the use of the chondro-os-seous graft to establish a continuous balanced growth of the mandible and midface without using any distrac-tion or osteotomy for correction of the deformity.

Materials and methodsThis work conforms to the values laid down in the Declaration of Helsinki (1964). The protocol of this study has been approved by the relevant ethical committee related to our in-stitution in which it was performed. All subjects gave full informed con-sent to participate in this study. Ani-mal care was in accordance with the institution guidelines.

Thirty-seven children were treat-ed by reconstruction of the TMJ by chondro-osseous graft in three dis-eases that required biological recon-struction of the TMJ for restoration of function, growth, remodelling and repair. These diseases were ankylo-sis, hemifacial microsomia and hypo-plasia of the condyle. This graft was tested experimentally for viability in the TMJ, in new environments of articulation with the glenoid fossa and masticatory function to meet the force of mastication and to restore the growth of the condyle, mandible

contact with the base of the skull. Continuous growth toward the base of the skull and downward growth toward the body is important in the growth of the mandible and midface.

The hypothesis of the condylar cartilage as a growth centre was not accepted in the past by many researchers worldwide, including Poswillo (1974). He stated that the condyle has no active role in the growth of the mandible and mid-face. This statement was based on the theory that continuous growth of the condyle leads condylar hyper-plasia1. Moreover, the growth of the mandible and midface occurs due to the functional demand of the peri-osteal matrix of the facial skeleton2. This theory is no longer accepted by the author, as the only theory to control growth by proving that the condyle is a growth centre was based on his experimental and clini-cal studies involving excision of the condyle in a new born rabbit (age, 3 months); 3 months later, he noticed a severe deformity of the lower jaw in the affected side3–7. However, we did not exclude Moss’s theory on functional demand of periosteal ma-trix, and we accept both theories to establish the growth of the mandi-ble and midface.

During TMJ ankylosis as a result of traumatic injury to the condyle and capsule contents with limita-tion of mouth opening due to intra-articular haemorrhage, pain, oedema and spasm of the TMJ muscles in a child, with formation of callus later between the skull base and the as-cending ramus of the mandible, ends with damages to the functional peri-osteal matrix of muscles involved in mastication and ligaments of the TMJ and bone. This severe insult greatly affected the growth of the mandible and midface. Compensatory growth in the muscular attachment of mas-ticatory muscles occurred as a result of TMJ stiffness and elongation of coronoid, short ramus, prominent angle and downward inclination of

of 7

Research study



mpe

ting

inte

rest

s: n

one

decl

ared

. Con

flict

of i

nter

ests

: non

e de

clar

ed.

All

auth

ors

cont

ribut

ed to

con

cepti

on a

nd d

esig

n, m

anus

crip

t pre

para

tion,

read

and

app

rove

d th

e fin

al m

anus

crip

t.A

ll au

thor

s ab

ide

by th

e A

ssoc

iatio

n fo

r Med

ical

Eth

ics

(AM

E) e

thic

al ru

les

of d

iscl

osur

e.

Post-mortem and histological studies of the graftMacroscopic featureSurgical reconstruction of the TMJ in rabbits by chondro-osseous graft rapidly adapted to the new function of masticatory process requirements and formed condyle and neck similar to the TMJ of the control animals. On macroscopic examination of the TMJ,

ResultsAll animals showed neither restric-tion of mouth opening nor diffi-culty in mastication; by the end of the experiment after 3 months, the rabbit gained approximately 0.8 kg of body weight, one animal had an infection in the TMJ, which was controlled by antibiotics, and in one rabbit, the graft got displaced due to a technical error; this had no ef-fect on the masticatory process of the rabbits, occlusion was good and two animals showed a midline shift (Figure 2).

Figure 2: Deformity of the lower jaw of a rabbit due to condyle resection in the affected side.

we found an excellent union between the chondro-osseous graft and the ra-mus with no evidence of bony resorb-tion, ossification or chondrofication of the graft. There was no corrosion around the stainless steel wires at the site of graft fixation, and no evidence of infection or changes in the colour of the wire, giving the impression of a biologically inert stainless steel wire. The animals were killed and the graft was dissected and kept in 10% buff-ered formalin for 10 days, immersed in 4-N formic acid for decalcification and stained by haematoxylin and eo-sin (H&E) (Figure 3A & B).

Microscopic studiesThe histological studies showed that the cellular pattern of the cells resem-bled the cellular pattern of the his-tology of the non-operated condyle with four distinct zones as layers of endochondral ossification; the first layer represents the articular layer and consists of a thick fibrocartilage cap layer; the second layer consists of several active mesenchyme stem cells, representing the proliferative layer; and the third layer showed the cells of the iliac crest converted from vertical columnar growth pattern of

Figure 1: (A) Chondro-osseous graft from the iliac of a rabbit showing the cap of the cartilage and the osseous element beneath. (B) Chondro-osseous graft from the iliac of a child showing the cartilage part attached to the bone shaft.

Figure 3: (A) Resected condyle of a rabbit. (B) Post-mortem specimen of the TMJ showing the chondro-osseous graft united to the ramus after 3 months.

of 7

Research study



petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

. A

ll au

thor

s co

ntrib

uted

to c

once

ption

and

des

ign,

man

uscr

ipt p

repa

ratio

n, re

ad a

nd a

ppro

ved

the

final

man

uscr

ipt.

All

auth

ors

abid

e by

the

Ass

ocia

tion

for M

edic

al E

thic

s (A

ME)

eth

ical

rule

s of

dis

clos

ure.

Figure 4: (A) Histology of the chondro-osseous graft after reconstruction of the TMJ by the graft showing four distinct zones, the thick fibrocartilage layer, the second layer showing active granular mesenchyme stem cells with different layers and the third layer showing chondrocyte differentiated to hypertrophic chondrocyte and osteoid bony tissue (H&E, ×80). (B) Histology of the chondro-osseous graft showing four distinct stained layers (Masson stain, ×80).

prevent any obstacle for full move-ments of the joint after reconstruc-tion by chondro-osseous graft. The operation was performed using full thickness of fascio-cutaneous of the auricular-temporal flap with further extension of the flap posteriorly for better and easy access to the TMJ and to avoid vital structures of the area.

The dissection of the flap was start-ed from the temporal region; reflec-tion of the flap was done by Haworth elevator inserted down to the tempo-ral process of the zygomatic arch and capsule of the TMJ incised through L-shaped incision for exposing the ankylosis. Haworth periosteal eleva-tor was inserted behind the posterior border of the neck of the condyle as a quid for insertion of special condylar retractor as designed by the author to protect the underlying soft tissue structures and maxillary artery, an-other incision was done in the sub-mandibular area for reattachment of the masseter and medial pterygoid muscles and also used an access for insertion and fixation of the graft. When the graft advanced upwards to the glenoid fossa, the graft was fixed to the ascending ramus by stainless steel wires of 0.5 mm; these cases showed an excellent result to mouth opening or growth of mandible and midface3,4.

This procedure was only applied on ankylosed joint. All cases showed good results, except two cases; in one case, all procedures and steps for reconstruction of the condyle by chondro-osseous graft was done, but the coronoid process left without re-section. After few years, we noticed that mouth opening was reasonable but not maximum and the growth of the face was unsatisfactory. We thus decided to intraorally resect the cor-onoid to establish a fully functional movement and to enhance growth (Figures 6A, 6B, 7A–E and 1B).

The fault in the second case is that the operation was performed with-out resection of the coronoid due to technical errors; this fault ends with

weight bearing in the iliac crest to a multidirectional growth fashion simulating the condyle due to chang-es in the environment from the iliac crest to masticatory requirement of the graft in the TMJ. In this layer, endochondral ossification occurred; in this zone, the chondrocyte under-goes differentiation through a series of changes to hypertrophic chondro-cyte and the endochondral cells con-verted into osteoid cells. This layer was similar to the third layer in the control group but slightly thicker and more active. The fourth layer rep-resents the osteoid layer with bony trabecular and bone morrow spaces in between and contains living cells arranged in a multidirectional fash-ion and distributed according to the direction of the masticatory forces (Figures 4A, 4B, 5A and 5B).

Clinical applicationThe clinical cases were divided into the following:

• Cases with ankylosis of the TMJ

• Cases with mild first arch dysplasiasyndrome

• Cases with hypoplasia of the con-dyle due to trauma or infection

There were two diseases showinghypoplasia of the condyle. The first one due to embryonic defects as a result of early occlusion of stapedial artery, the main nutrient vessel of the first arch, and the second one due to trauma affecting only the condyle, while in other diseases of ankylosis, the traumatic episode not only af-fects the condyle but also the content of the TMJ capsule with fragmenta-tion of the meniscus and may even extend to the base of the skull.

The pathogenesis of these diseases differs, but basically, the treatment of these cases remains the same. All cases required early reconstruction by the chondro-osseous graft for res-toration of growth and function.

All cases of TMJ ankylosis in chil-dren were treated by excision of the ankylosed joint, with hyperplas-tic coronoid (coronoidectomy) to

of 7

Research study



mpe

ting

inte

rest

s: n

one

decl

ared

. Con

flict

of i

nter

ests

: non

e de

clar

ed.

All

auth

ors

cont

ribut

ed to

con

cepti

on a

nd d

esig

n, m

anus

crip

t pre

para

tion,

read

and

app

rove

d th

e fin

al m

anus

crip

t.A

ll au

thor

s ab

ide

by th

e A

ssoc

iatio

n fo

r Med

ical

Eth

ics

(AM

E) e

thic

al ru

les

of d

iscl

osur

e.

Figure 5: (A) Histological section showing differentiation of chondrocyte to hypertrophic chondrocyte (H&E, ×400). (B) Histological section showing hypertrophic chondrocyte converted to osteoid tissue and bone marrow spaces in between.

Figure 6: (A) Tomography of TMJ ankylosis of a child. (B) Tomography of the TMJ reconstructed by chondro-osseous graft after 2 years with normal functional movements.

recurrence of ankylosis. Further, the patient did not attend our follow-up clinic until puberty. The case was treated later by complete excision of the ankylosed mass with the coro-noid as one piece, and the TMJ was replaced by silastic prosthesis.

The principle underlying the man-agement of hemifacial microsomia required many steps. The first step involved correcting the angle of the mouth (commissuroplasty) by

measuring the length of the upper lip from midline to opposite normal angle of the mouth, which is usually approximately ±30 mm, and to meas-ure 30 mm on the working cleft side, the lower lip measurement usually shorter by approximately ±25 mm after the marking, the cleft excised by oblique incisions to restore a normal angle, the angle sutured first and the muscles of the modules then get spe-cial attention, the mucosa is sutured

in layers; all remnants of the Meckel’s cartilage are excised. In the second step, platysma muscle flap was trans-ferred from the neck for building the atrophied masseter muscle and for making a good muscular covering or bed for the chondro-osseous graft nourishment, followed by recon-struction of the zygomatic arch by a strip of bone from the opposite iliac crest after measuring the defect of the zygomatic arch; the piece of the bone is usually secured by a stainless steel wire of 0.5 mm, a piece of car-tilage from the ear was used for re-construction of the glenoid fossa; few months later, TMJ reconstruction was done by the chondro-osseous graft. The last step, carried out 1–2 years later, involves correcting the ear. All cases showed good result without using distraction or osteotomies, but orthodontic treatment was required for correction of the occlusion. An-aesthesia was difficult and required an experienced anaesthetist to per-form blind intubation due to deform-ity of the upper respiratory tract in both TMJ ankylosis or in cases with hemifacial microsomia.

The aetiology of condylar hy-poplasia may be traumatic, usu-ally unilaterally; the growth of the mandible was affected but not the masseter muscle or mouth open-ing and without formation of an-tegonial notch in the lower border of the mandible as observed in TMJ ankylosis. However, the ascending ramus may be medially displaced and shorter than the normal side, exploration of the TMJ showed a small and tiny condyle of 4 mm width and 3 mm height. Small con-dyle was excised and reconstructed by chondro-osseous graft to restore the normal growth of the condyle; the glenoid fossa was intact with normal shape and also the coro-noid process and zygomatic arch. In short children, if the iliac crest was not high, we used 3 cm of the chondro-osseous graft for TMJ reconstruction.

of 7

Research study



petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

. A

ll au

thor

s co

ntrib

uted

to c

once

ption

and

des

ign,

man

uscr

ipt p

repa

ratio

n, re

ad a

nd a

ppro

ved

the

final

man

uscr

ipt.

All

auth

ors

abid

e by

the

Ass

ocia

tion

for M

edic

al E

thic

s (A

ME)

eth

ical

rule

s of

dis

clos

ure.

DiscussionAutologous bony structures for recon-struction of the TMJ have been great challenges to maxillofacial surgeons for the past four decades. Two bio-logical techniques have successfully been used: the costo-chondral graft and the chondro-osseous graft for reconstruction of the TMJ, and both techniques were experimentally test-ed for assessment of these grafts for viabilities for growth potential and masticatory force processes. Ken-nett8 tested the costo-chondral graft

clinically, and Poswillo9 studied the graft experimentally on iris monkeys. In his experiments, he used the cos-to-chondral graft for reconstruction of the TMJ condyle on monkeys and he also did a vertical sub-sigmoid os-teotomy on the posterior border of the ascending ramus for sliding the posterior segment upwards to fill the glenoid fossa and to simulate the condyle after resection and to work as a stump. He found that the costo-chondral graft successfully replaced the condyle as a good substitute for

restoration of growth and function of the condyle, but in the sliding graft, he found that it replaced the condyle for functional movements, without any evidence for growth potential.

The author did an experimental study using rabbits by reconstruc-tion of the condyle by chondro-os-seous graft harvested from the iliac crest of rabbits. After 3 months, the animals were sacrificed for post-mortem studies of the TMJ speci-men. We found excellent healing and union between the chondro-osseous

Figure 7: (A) Deformity of a face of a 4-year-old child due to TMJ ankylosis of the left side of the face. (B) CT scan of the left TMJ showing deformity of the joint. (C) Post-operative photograph showing remarkable growth of the face after 3 months. (D) Mouth opening after operation. (E) Lateral oblique of the left side of lower jaw showing reconstruction of the left TMJ by chondro-osseous graft after 3 months.

of 7

Research study



mpe

ting

inte

rest

s: n

one

decl

ared

. Con

flict

of i

nter

ests

: non

e de

clar

ed.

All

auth

ors

cont

ribut

ed to

con

cepti

on a

nd d

esig

n, m

anus

crip

t pre

para

tion,

read

and

app

rove

d th

e fin

al m

anus

crip

t.A

ll au

thor

s ab

ide

by th

e A

ssoc

iatio

n fo

r Med

ical

Eth

ics

(AM

E) e

thic

al ru

les

of d

iscl

osur

e.

repair and remodel due to the pres-ence of mesenchyme stem cells.

References1. Carlsson GE, Oberg T. Remodelling ofthe temporomandibular joint. Oral Sci Rev. 1974;6:53–86.2. Moss ML. The primary of functionalmatrices in orofacial growth. Dent Proc Dent Rec. 1968 Oct;19(2):65–73.3. Kummoona R. Biological reconstruc-tion of the temporomandibular joint by chondro-ossous graft, clinical and experi-mental study. J Craniofacial Surg. 2013 May;24(3):792–6.4. Kummoona R. Temporomandibular joint reconstruction with a 2 part chrome cobalt prosthesis, chondro-ossous graft and silastic clinical and experimen-tal studies. J Craniofacial Surg. 2009 Nov;20(6):2125–35.5. Kummoona R. Chondro-ossous iliaccrest graft forone stage reconstruction of ankylosed joint in children. J Maxillofa-cial Surg. 1986 Aug;14(4):215–20.6. Kummoona R. Functional rehabilita-tion of ankylosed temporomandibular joint. Oral Surg Oral Med Oral Path. 1978 Oct;46(4):495–505.7. Kummoona R, Al Mudafer M. Recon-struction of mandibular condyle by chondro-ossous iliac graft (Experimen-tal study in Rabbit). IPMJ. 2004 Jan;3: 98–102.8. Kennett S. Temporomandibular jointankylosis the rational for grafting in the young patients. Oral Surg. 1973 Oct;31(10):400.9. Poswillo D. Biological reconstruction of mandibular condyle. Brit J Oral Maxillofa-cial Surg. 1987 Apr;25(2):100–4.10. Kummoona R. Posttraumatic missileinjuries of the orofacial region. Craniofac Surg. 2008 Mar;19(2):300–5.11. Kummoona R. Reconstruction ofthe mandible by bone graft and met-al prosthesis. J Craniofac Surg. 2009 Jul;20(4):1100–7.12. Rhode Island Hospital Report. Recentadvances in connective tissue cell. Dev Biol. 2011 May.13. Poswillo D. Experimental reconstruc-tion of mandibular joint. Int J Oral Surg. 1974;3:400–6.14. Ware WH, Brown S. Growth center transplantation to replace mandibu-lar condyle. J Maxillofacial Surg. 1981 Feb;9:50–8.

In this study, they also found that a G-protein coupled receptor (CXCR4) is predominantly expressed in hyper-trophic chondrocyte, while its ligand chemokine stromal cell-derived fac-tor (SDF-1) is expressed in the bone marrow adjacent to hypertrophic chondrocyte10,12.

The objection about chondro-osse-ous graft once harvested from the il-iac crest may affect the growth of the iliac bone in children. During follow-up, we did not observe any deformity of the iliac crest. During follow-up, none of the patients complained about it; the second objection is the use of stainless wire which may cause infection; the author has been prac-ticing wire fixation for the last four decades successfully for the fixation of fragments of bones in maxillofa-cial surgery including bone grafting, injuries or fixation of fragments after osteotomy in facial deformity or in controlling bone fragments in cases with blast war injuries10,11.

The chodro-osseous graft been used successfully by the author for the last four decades for the recon-struction of TMJ ankylosis in chil-dren and also for the reconstruction of TMJ with hemifacial microsomia, first arch dysplasia syndrome and in cases with traumatic hypoplasia of the condyle10. The result was very optimistic in all cases for restoration of growth, function and aesthetic features of the face, and the graft did not show resorbtion or substitution by ossification or chondrofication. Further, the condyle and TMJ were able to fulfil the functional demands of growth, remodelling and repair of the condyle due to the presence of mesenchyme stem cells3.

ConclusionDamages of the TMJ as result of congenital or acquired traumatic diseases in children require an ur-gent reconstruction of the joint by chondro-osseous graft. This graft has an ability to withstand the force of mastication and to continually grow,

graft and the ramus; the graft was fixed by stainless steel wire with no evidence of infection around the wire, corrosive properties of the wire or changes in the colour of the wire. The graft not only restored growth but also withstood the mas-ticatory forces. The histological studies of the chondro-osseous graft showed four layers or zones; the first articulation layer of fibrocarti-lage was thick due to the demands of masticatory forces of hard food in rabbits. The second layer showed several zones of active granular mesenchyme stem cells that repre-sented the proliferative layer. The third layer showed the chondrocyte and osteoblast layer and conver-sion of chondrocyte to osteoid tis-sue, the chondrocyte differentiate to hypertrophic chondrocyte, and the fourth layer comprised an osteoid layer and bone marrow spaces. The third layer represents the differen-tiation of mesenchyme stem cells to chondrocyte and osteoblast; these cellular changes represent the in-trinsic growth potential of chondro- osseous graft3–7.

Surprisingly, the cartilaginous part of the chondro-osseous graft has an ability to change its growth pattern from vertical growth in the iliac crest to multidirectional growth once the environment of the graft has changed from a weight bearing to masticatory function in the TMJ. This function en-hances the growth of the graft and helps in continual remodelling and repair3–7,10,11.

Recently, research on connective tissues for cell differentiation found the value of chondro-osseous junc-tion of the graft to maintain growth, repair and remodelling due to the intrinsic growth potential in the graft due to the presence of mesenchyme stem cells. During endochondral bone formation in the chondro-osse-ous graft, chondrocyte cells undergo differentiation towards hypertrophy and before they are replaced by the bone and bone marrow.

role of mesenchyme stem cells in the chondro-osseous graft ...page 1 of 7 research study icensee...

Documents