hydroxyapatite collagen scaffold

2. INTRODUCTION
 The temporomandibular joint (TMJ) is one of the cornerstones of craniofacial
function.
 Unhindered TMJ function, in addition to being indispensable for vital functions
such as eating, respiration, speech, also has a pivotal role in craniofacial growth.
 One of the major causes of disruption of TMJ function is TMJ ankylosis, which
can lead to crippling facial asymmetry, severe retrusion of the mandible in
bilateral cases, inadequate nutrition, poor oral hygiene, adverse psychological
effects, and numerous other difficulties

3.  TMJ ankylosis has a higher incidence in the developing world, particularly in
India.
 The problem here is unfortunately further compounded by factors such as
mismanagement, lack of awareness, inadequate economic means, insufficient
access to care, and limited infrastructure (Gupta et al., 2012).
 The mainstay of current management of TMJ ankylosis is surgery, which
involves osteoarthrectomy with placement of interposition material and/or
reconstruction of the joint.

4.  Currently, there is a wide spectrum of autogenous and alloplastic TMJ
reconstructive options available at the disposal of a maxillofacial surgeon.
 Autogenous grafts are associated with significantly lower chances of graft
rejection, as well as with the potential for growth (costochondral graft or
sternoclavicular graft), and cost-effectiveness.
 However these grafts are associated with significant donor site morbidity,
technical sensitivity, delayed functional loading, unpredictable results, high
failure rates, and the risk of re-ankylosis (Mohan et al., 2014).

5.  Among the alloplastic options, total joint prosthesis has been studied extensively.
 There are several advantages to total joint replacement, especially with a patient-
fitted prosthesis, including
 earlier return to function,
 lower postoperative pain scores,
 better replication of functional anatomy,
 avoidance of donor site morbidity and earlier postoperative physiotherapy
(Ferreira et al., 2014).
 However, in addition to concerns such as potential material wear/failure and long-
term stability, the steep cost of alloplastic joints precludes their applicability
among patients of all socioeconomic groups, particularly in the developing world).

6.  Another option for condylar regeneration following osteoarthrectomy is
transport distraction of the posterior border of the ramus, in a cranial
direction.
 However this involves technically sensitive surgery and meticulous vector
control.
 Additionally, the prolonged period of consolidation with the accompanying
risk of infection and the need for a subsequent distractor removal procedure
makes this option less appealing to patients.

7.  The future of reconstruction implants lies in bio-scaffolds and tissue
engineering.
 Recently bone marrow derived mesenchymal stem cells (BMSC) have been
in focus for their role in bone regeneration.
 Mesenchymal stem cells (MSCs) are nonhematopoietic stromal stem cells
that are almost ubiquitously distributed in the body.
 Although these cells can be found in bone marrow, adipose tissue, muscle,
periosteum, tendon, peripheral cartilage, ligament, potentially contributing to
replenishment of these tissues (Wang et al., 2013).

8.  The application of bone marrow aspirate (BMA) for bone regeneration has
been widely used, with favorable outcomes.
 Paley et al. Reported accelerated healing of 2-cm bony defects in rabbits after
percutaneous bone marrow grafting (paley et al., 1986).
 In a series of primary sarcoma patients treated by extensive en bloc
resections and internal fixation who developed delayed union or non-union,
Healey et al. Reported successful union in five of the eight patients and
evidence of bone formation in seven patients
 Five of whom had received chemotherapy and one radiotherapy (healey et al.,
1990).

9.  Subsequently, Connolly et al. reported successful re-union of eight of 10 tibial
non-unions and 10 of 10 fractures with percutaneous bone marrow grafting in
combination with adequate immobilization (Connolly et al., 1991).
 Additionally, there have been reports of bone regeneration using BMSC
incorporated in osteo-conductive scaffolds.
 They have been used for pseudo-arthrosis of long bones, avascular necrosis of
the femoral head, simple bone cysts, sinus augmentation, alveolar augmentation,
distraction osteogenesis, and various other applications (Tripathy et al., 2013; Lin
et al., 2010).

10. MATERIALS AND METHODS
 Pediatric patients with TMJ ankylosis who visited our outpatient clinic and whose
parents opted for condylar regeneration, between August 2014 and February
2015,were included in this study
 Ethical clearance was obtained from the institutional research cell.
 Informed consent was obtained from the patients' parents.
 Limited mouth opening was the chief complaint of all of the patients. A thorough
history was recorded, and the cause of ankylosis was ascertained.

11.  Evaluation was done for facial asymmetry, occlusion, maximal mouth
opening, protrusive movements, and growth pattern.
 Cephalograms, panoramic views, and CT scans were obtained for
assessment of the ankylotic chunk and measurement of the ramal length
mismatch of the two sides.
 All patients underwent operations under general anaesthesia, with fiber-optic
guided naso-endotracheal intubation.
 The TMJ was exposed through a standard Al-Kayat Bramley incision, and the
ankylotic chunk was resected aggressively to create a gap of about 1.5 cm.

12.  In addition, a coronoidectomy on one or both sides was performed to gain a
minimum of 35 mm intraoperative mouth opening, following Kaban's protocol.
 The glenoid fossa was contoured with suitable burs to allow for seating of the
prepared graft.
 Bone marrow aspiration was performed under a strict aseptic protocol using an
18-gauge bone marrow aspiration needle from the posterior iliac crest

13.  .
 A 2-ml quantity of marrow was collected. Hydroxyapatite/collagen (HA/Col) marketed
as a block (Surgiwear®), in a 60:40 ratio and with 60% porosity, was prepared by
carving it to the shape of a condyle
 It was then fixed to the ramus by a trapezoidal, four-hole, titanium miniplate and
screws.
 A collagen sponge soaked in BMA was interposed between the raw bone of the
osteotomized condylar stump and the HA/Col block.
 Also, temporal fascia was interposed between the glenoid fossa and the graft. The
wound was closed in layers.
 Physiotherapy was started on postoperative day 10. All patients were followed up for
1 year

14.  Success of the procedure was graded by assigning a score at successive follow-
ups based on the degree of mouth opening.
 A mouth opening of 35 mm was graded as 5, 30-35 mm as 4, 25-30mmas 3, 20-
25mm as 2, and 10-20mm as 1.
 The TMJ score was assessed before and after the procedure, by scoring diet and
chewing, speech, activity, recreation, mood, and anxiety on a five point ordinal scale
(5 ¼ excellent, 1 ¼ poor).

16. RESULTS
 Seven patients were included in this study, with a mean age of 9.71 (±3.30) years, ranging
from ages 5 to 14 years.
 Of these seven patients, four had right TMJ affected, two had left, and one patient had
bilateral TMJ ankylosis.
 The male-to-female ratio was 5:2. Five patients had a history of trauma, and two patients
had chronic ear infection.
 None of the patients had recurrence from previous surgery.
 The mean preoperative mouth opening was 4.14 (±2.3) mm, which improved to 29.86
(±3.67) mm at 6-month follow-up and to 34.57 (±3.78) mm at 1-year follow-up.

17.  The mean protrusive movement improved from 0 to 2.86 (±1.1) mm.
 The mean success score was 4.43 out of 5
.
 There was significant improvement in the TMJ score in regard to all parameters,
with a mean of 3.94

19. DISCUSSION
 The importance of reconstruction of the joint and maintenance of ramal height
especially in young patients following osteoarthrectomy cannot be stressed
enough.
 Resection of the fused condylar stump invariably creates a reduction of
posterior ramal height.
 In biomechanical terms, this shifts the point of rotation (fulcrum of lever that is
the mandible). The previously class III lever (with the load at the molars and
fulcrum at the TMJ and effort at the pterygo-masseteric sling) now changes to
a class I lever with the fulcrum at the molars.

20.  This creates instability, with propensity for the mandible to shift postero-
superiorly with simultaneous creation of an anterior open bite.
 Also this obviously disrupts the facial soft tissue matrix, which restricts
harmonious craniofacial growth, especially if the patient presents before
attainment of skeletal maturity.
 On the contrary, if the posterior ramal height is maintained by means of condylar
reconstruction, the class III lever relationship can be maintained.

21.  Early onset of joint ankylosis, in unilateral joint involvement, may result in
restricted vertical growth with accompanying occlusal cant.
 In these patients, reconstruction of the joint with slight overcorrection of ramal
height, following release of ankylosis, may initially result in a posterior open bite.
 However, this gap soon becomes closed by supra-eruption of teeth.
 Thus, condylar reconstruction in these cases could theoretically cause gain in
vertical height (acting somewhat like a functional appliance) with correction or at
least improvement of mild to moderate occlusal cant.

22.  Our method of condylar bone reconstruction, proposed in this series, involves the
placement of osteoinductive marrow on an osteo-conductive bio-scaffold, which has
been reported with platelet-rich plasma .
 Author favorable clinical experience with the use of hydroxyapatite scaffold and
BMA in maxillofacial bony defects prompted us to choose it for use in this study.
 It is a simple, cost-effective procedure, involves no donor site morbidity, and is
suitable for young patients who have greater capacity for remodeling and
regeneration.
 Also, the bone marrow in young patients has higher osteogenic potential due to the
longer lifespan of marrow MSCs (Stenderup et al., 2003).

23.  The major drawback of using unprocessed marrow is the relatively low yield of
MSCs.
 To maximize the yield, various investigators have proposed that the volume of
marrow harvested in a single aspiration be limited to 2 ml (Muschler et al., 1997;
Batinic et al., 1990).
 The exact mechanisms of tissue regeneration brought about by stem cells are still
being elucidated, but there has been some advancement of knowledge in this
field.

24.  The stem cell niche acts as a local pool of cells and aids in tissue repair.
 Studies indicate that, following trauma or injury, there is homing or trafficking of
circulating MSCs to the site of injury (in a manner similar to leucocyte
recruitment).
 Following their recruitment to sites of injury, stem cells act by two principal
mechanisms:
 either by proliferating and restoring the cytoarchitecture of host tissues, or
 by acting in a paracrine fashion, secreting a host of signaling molecules and
growth factors that foster a regenerative micro-environment referred to as
“trophic activity” (Si et al., 2011; Fong et al., 2011; Caplan, 2007).

25.  Although a thorough appraisal of these mechanisms is beyond the scope of this
discussion, one can readily appreciate the premise for augmentation of the local
stem cell pool by grafting MSCs harvested from the patient's own bone marrow to
the site of injury.
 In this series, none of the patients experienced reduced mouth opening due to
reankylosis in the follow-up period of 1 year.
 One of the patient developed temporary weakness of the facial nerve, which
resolved with supportive treatment within 3 months.
 One patient experienced graft infection, necessitating re-exploration and graft
removal.

27. CONCLUSION
 HA/Col bio-scaffold enriched with bone marrow aspirate is a safe
and cost-effective alternative for reconstruction of the mandibular
condyle, particularly in growing individuals with high osteogenic
potential

28. RELATED ARTICLES

30.  Aim of this study was to evaluate the feasibility of using preshaped
hydroxyapatite/collagen condyles as carriers for platelet-rich plasma after gap
arthroplasty in patients with temporomandibular ankylosis, to assess the aesthetic and
functional outcomes, and to find out if neocondylar regeneration was possible
.
 19 patients with temporomandibular joint ankylosis (25 joints), in whom preshaped
hydroxyapatite/collagen condyles with platelet-rich plasma were fixed to the ramus with a
titanium miniplate, and temporal fascia was placed in between.
 Study evaluated the type of ankylosis, mouth opening before and after operation,
deviation on mouth opening, lateral excursion, protrusion, postoperative anterior open
bite, radiographic assessment, and complications.

31.  All patients showed appreciable improvements in mouth opening and
excursion of the jaw. There were a few complications such as mild fever, and
temporary involvement of the facial nerve, which improved with time.
 No open bite or recurrence was reported during the 18 months’ follow up.
 Radiographic evaluation at 3 months showed a less opaque condyle, but the
opacity at 18 months was more defined, suggesting a newly formed condyle

32.  A preshaped hydroxyapatite/collagen condyle with platelet-rich plasma
improves both aesthetics and function.
 However, a long term study is required to follow the growth patterns to see if
the patients develop any facial deformity as they grow.

33. Clinical orthopedic and clinical research

34.  From July 1984 to December 1985, eight patients were selected who had unsuccessful
healing of osseous reconstructions after lower-extremity resections for sarcomas affecting
bone
 Cases were selected for percutaneous bone marrow grafting when, in the opinion of the
surgeon, there was no clinical or roentgenographic evidence of progress toward union
 . Four of eight cases had atrophic-type nonunions. a hypertrophic nonunion, a
hypertrophic nonunion of a vascularized fibular graft, and a nonunion of an intercalary
vascularized fibular graft fracture

35.  The presence of poorly vascularized tissue due to previous muscle resection,
radiotherapy, or scar formation was regarded as a reason to avoid an extensive open
surgical procedure that would have a high risk of infection, wound-healing problems, or
neurovascular injury. These poor-risk cases were believed to be particularly suited to the
percutaneous bone marrow graft technique.
 Primary tumors were osteogenic sarcoma (five), chondrosarcoma (two), and malignant
fibrous histiocytoma (one).
 Five patients had failed autogenous iliac crest bone grafting at the time of initial
reconstruction.

36.  Six of eight patients had secure internal fixation remaining at the time of bone marrow
grafting that maintained a roentgenographically evident gap in their osseous
reconstruction.
 All patients have been continuously free of disease for a mean of 46 months.

37.  After induction of general anesthesia, the donor iliac crest(s) and the recipient area to be
grafted were prepared in isolated sterile fields to prevent cross contamination
 A 14-gauge biopsy needle with a non heparinized syringe was used for aspiration and
injection of the marrow in an effort to minimize trauma to the cells
 Immediately after aspiration, under fluoroscopic control, each aspirate was injected
throughout the site of nonunion until a total volume of 50 ml of bone marrow had been
grafted.

38.  Fourteen injections were performed in eight patients. Repeat injections were done
when no healing progress was seen on review of serial roentgenograms and patients
consented to readmission.
 Seven of eight patients formed bone after marrow grafts. Eleven of 14 injections
produced new bone formation within three months of injection.
 Unstable fixation would permit bone formation to occur after marrow grafting,
nevertheless, no union occurred in the face of motion between bone fragments

39. The Journal of Implant & Advanced Clinical Dentistry

40.  Maximum of 4 cc bone marrow was aspirated from a single site for two
patients.
 In the first patient, two block allograft sources for scaffolding were used for the
anterior ridge augmentation procedure.
 The blocks were shaped, injected with heparinized marrow aspirate, and
secured in the surgical site with bone screws.
 In the second patient, pure phase b-tricalcium phosphate particulates were
mixed with bone marrow aspirate for augmentation of the right and left
maxillary sinuses.

41.  After approximately 5 months of healing, a bone core biopsy sample was
taken from the sinus augmentation site with a trephine drill.
 Histomorphometric analysis of the sample revealed 36% new vital bone
formation
 The bone marrow aspirate combined with allograft or alloplast grafts are
effective alternatives to autogenous bone grafts in the oral region.

42. THANK YOU