The minimization of morbidity in cranio-maxillofacial osseous reconstruction

Bone graft harvesting and coral-derived granules as a bone graft substitute

George Kálmán Béla Sándor

Institute of Dentistry, University of Oulu
Department of Oral and Maxillofacial Surgery, Institute of Dentistry, University of Oulu

Abstract

Reduction of morbidity in osseous reconstruction of cranio-maxillofacial bony defects could come from development of less invasive bone graft harvesting techniques or by elimination of bone graft donor sites using a bone graft substitute. This work studies outcomes and morbidity associated with these two approaches.

A power-driven trephine was used to harvest bone from the anterior iliac crest using a minimally invasive surgical technique. Initially the safety of the technique was evaluated in a cadaver model. Twenty-five freshly preserved adult cadavers had a total of 250 cancellous cores of bone harvested from 50 anterior iliac crest sites. Twenty intentional perforations were made to the maximum depth possible with the instrumentation tested. No encroachment upon the peritoneum was found.

A total of 84 patients had 333 cores of cancellous bone harvested using the same approach with a complication rate of 3.6% and a patient satisfaction rate of 98.8%. In a further 76 patients the motorized trephine method was compared to traditional open iliac crest corticocancellous block harvesting. The trephine group ambulated earlier, required fewer days of hospital stay and had significantly lower pain scores than the open iliac crest group.

Coral-derived granules were used as a xenograft bone graft substitute to treat bony defects in the cranio-maxillofacial skeletons of 36 patients with 54 sites and followed for 12 to 36 months. The augmentations produced satisfactory results with the following complications noted: overt wound infection 1.8%, wound irritation 3.8% and clinically evident resorption in 9.3% of augmented sites.

Coral-derived granules were then used to treat 48 dento-alveolar defects in 21 growing patients with trauma induced tooth-loss in the anterior maxilla and elective ankylosed tooth removal in the posterior maxilla and mandible. Coral granules were significantly more efficacious in reconstructing alveolar defects in the posterior maxilla or mandible (93.5%), than the anterior maxilla (17.6%).

The minimally invasive technique using a power driven trephine was successful at reducing morbidity from bone graft harvesting at the anterior iliac crest. Coral-derived granules can be used in selected situations as a bone graft substitute and minimize post surgical morbidity by eliminating the bone graft donor site.

Dedication

To My Dear Children, Kinga, Eniko and Hunor,

For yours are the many wonderful future goals to strive for...

Table of Contents
Acknowledgements
Abbreviations
Glossary of terms
List of original papers
1. Introduction
2. Review of the literature
2.1. Structure, function and physiology of bone
2.2. Bony defects in the cranio-maxillofacial skeleton
2.3. Unique aspects of alveolar ridge defects and resorption
2.3.1. Prevention of alveolar ridge resorption
2.4. Methods to augment deficient bone
2.4.1. Processes of bone healing
2.4.2. Local procedures to augment existing alveolar bone
2.4.3. Autografts
2.4.4. Allografts
2.4.5. Xenografts
2.4.6. Synthetic bone substitutes
2.4.7. Osteoactive agents
2.5. Harvesting autografts
2.5.1. Vascularized versus non-vascularized bone grafts
2.5.2. Potential non-vascularized donor sites
2.6. Bone graft harvesting methods at the iliac crest
2.6.1. Minimally invasive surgery
2.6.2. Trephines and the iliac crest
2.7. Coral-derived granules
3. Aims of the study
4. Materials and methods
4.1. Subjects and grafts
4.2. Methods and techniques
4.2.1. Surgery
4.2.2. Evaluation of the surgical outcomes
4.2.3. Statistics
5. Results
5.1. Cadaveric and patient cancellous core dimensions and perforations of the medial iliac cortical plate
5.2. Clinical course of anterior iliac crest harvesting methods
5.3. Cranio-maxillofacial reconstruction with coral-derived granules
5.4. Dento-alveolar reconstruction with coral-derived granules
6. Discussion
6.1. General comments
6.2. Methodological aspects
6.3. Reduction of morbidity
6.3.1. Safety of trephine harvesting of the anterior iliac crest
6.3.2. Morbidity with trephine harvesting
6.3.3. Morbidity with coral-derived granules in the cranio-maxillofacial skeleton
6.3.4. Morbidity with coral-derived granules in the dento-alveolar area
6.4. Clinical implications and recommendations
6.5. Future prospects
7. Summary and conclusions
References
List of Tables
1. Gender and age of the subjects participating in the five studies.
2. Distribution by location, of patients requiring augmentation of cranio-maxillofacial osseous contour defects using coral-derived granules in study IV.
3. Distribution of 48 sites of coral granule augmentations in 21 patients in study V.
4. Aetiology of tooth-loss and location of augmented alveolar ridge sites in study V.
5. Summary of study design, data handling and study periods of studies I to V.
6. Total number of cancellous cores harvested in studies I, II and III.
7. Post-operative morbidity following trephined cancellous core harvesting procedure. (Results of a telephone interview) in study II.
8. Time to unassisted ambulation and length of hospital stay following harvest of corticocancellous block grafts and cancellous cores from the anterior ilium in study III.
9. Maxillofacial and pelvic pain scores following harvest of corticocancellous block grafts and cancellous cores from the anterior ilium in study III.
10. Volume of coral granules placed by operative site in study IV.
11. Ability to place dental implants into coral-derived granule augmented sites without or with bone grafts in study V.
List of Figures
1. Photomicrographs showing the gradual incorporation of coral exoskeleton into mammalian bone. 1 Fibrovascular ingrowth. 2 Bony apposition onto coral exoskeleton. 3. Osteoclast resorbing coral skeleton 4. Woven bone replacing coral exoskeleton.
2. The osteocore with the pre-cutter and trephine drill bit.
3. The trephine totally engaged within bone.
4. The pre-cutter bit on the drill supported by a funnel-shaped winged positioner, which aids in obtaining proper axial inclination and stability.
5. Bone being expressed by the plunger from the drill mechanism.
6. View of the crest of the ilium with 5 cores drilled out. More bone can be obtained by entering the holes at different angles or simply removing the interseptal bone with Rongeurs.
7. Small stab incision used in the minimally invasive approach to bone graft harvesting to access iliac crest with motorized trephine.
8. Funnel-shaped trocar retractor in position protecting the surrounding soft tissues and ensuring a pathway to the cortex of the iliac crest.
9. Trephined cancellous cores harvested by motorized trephine.
10. Traditional open anterior iliac crest bone harvest with a 6 cm incision.
11. A. Pre-operative view of a defect in frontal bone in the right forehead region. B. Incision made above the hairline with syringe containing coral granules inserted into the wound to deliver granules into a subperiosteal pocket, distant from the incision. C. Soft mallet used to gently flatten granules deposited transcutaneously in the subperiosteal location to eliminate any edge effects. d Post-operative appearance of patient’s forehead.
12. Coral granules deposited into an alveolar extraction socket defect in as an inlay graft.
13. Histological section of a cancellous core with haematoxylin and eosin stain at 20x magnification. Note the largely cancellous structure of the core with minimal cortical bone on the superior-most aspect on the left side. The cancellous core is laden with endosteal cells.
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