Brit. J. Oral Maxillofacial Surgery (1998) 36, 346-352

REVASCULARIZED COMPOSITE GRAFTS WITH INSERTED IMPLANTS FOR RECONSTRUCTING THE MAXILLA - IMPROVED FLAP DESIGN AND FLAP PREFABRICATION

Vinzenz K, Holle J, Würinger E, Kulenkampff KJ, Plenk Jr. H, all Vienna, Austria

Abstract

A new technique for prefabricating a revascularised composite scapula flap to precisely fit a maxillary defect is presented.

The method is based on careful preoperative planníng, using three-dimensional (3D) reconstructions of CT- data and stereolithographic models. Then a pedicled scapula flap with a split skin graft envelope and inserted endosseous implants is prefabricated and covered by a Goretex®-membrane. After three to four months these prefabricated grafts are harvested, inserted into the maxillofacial defects, and reanastomosed to the facial vessels. Two to three weeks after successful reconstruction and mucosal healing, dental restoration can be performed with the osseointegrated implants.

This procedure is demonstrated step by step in a case of a 51-year-old female patient with a more than 13-year maxillary defect after resection of a protruding basal meningeoma.

Histological evaluation of an unused marginal part of the flap shows vital bone reactions and attachment of the split skin graft.

Key words: Microvascular reconstruction, maxillofacial defects, prefabricated scapula flap

Introduction

Measures to rehabilitate patients with maxillofacial defects include microsurgical revascularized flaps4,5,11,13,16,22,23,24,25 and implant-fixed prosthesis9,20.

Due to the complex anatomy of the maxilla, reconstruction of this region represents one of the most challenging tasks in reconstructive surgery24. Unlike in other maxillofacial areas e.g. mandibula-mouth floor5,11,22, osteomyocutaneous flaps from the iliac crest, scapula, or fibula are often too bulky for the midface region, thus impairing oral function. Furthermore they are too heavy and physiologically unsuitable for filling pneumatised cavities.

The considerable size of these flaps also interferes with the simultaneously performed osteosynthesis for flap fixation and vascular microsurgery within this area which is extremely limited in space.

The bone structure of the scapula would ideally fit into such maxillary defects7,12,13,24,27, but in order to avoid the bulky musculocutaneous coverage, prefabrication of a composite revascularized graft with all necessary components seemed the most suitable solution for this problem.

Prefabrication at the donor site comprises the preparation of the vascular pedicle, osteotomy of the scapula in the desired dimensions, insertion of endosteous dental implants, subtle soft tissue coverage by split skin grafts, and enveloping the flap by a Goretex®-membrane. It has to be performed about three to four months prior to microsurgical reconstruction since the healing of a subtle soft tissue coverage by split skin grafts and osseointegration of implants takes some time.

A comprehensive operation planning based upon 3D-CT diagnostic methods is the prerequisite for this prefabrication, resulting in an improved flap design for maxillofacial reconstruction.

This new procedure is demonstrated step by step in a 51-year-old female patient who had undergone maxillectomy and resection of a protruding meningioma of the skull base more than thirteen years earlier.

In addition first results from an ongoing histomorphological evaluation of these prefabricated flaps are presented.

Methods

Radiodiagnostic methods and preoperative planning

For this type of maxillofacial reconstruction the lateral border of the scapula is the preferred donor site, since it resembles remarkably the maxillary alveolus and palate7,12,13. As already described by other authors, precise preplanning is a must for complex reconstructive surgery1,2,8. A 3D-CT diagnostic system is used to determine size and shape of the flaps and then for the correct positioning of the implants.

CT data were aquired using a Siemens Somatom HiQ in high resolution mode and thicknesses of the slices were 2 mm. Initial planning was performed by a high speed image operation system (ARRI-Voxel-Flinger) with complete interactive 2D- and 3D- possibilities of visualisation and manipulation (Figs. 1a, 1b, 2a). The sections from the CT device having been saved, this system provides manifold interactive image manipulations via graphic work station and appropriate software (Fig. 2a). Using this system, the bony defect in the maxillofacial region and the appropriate part of the lateral border of the scapula can be correlated (Figs. 1b, 2a) as well as the position of implants exactly defined before surgery (Fig. 2a). The precision of this preoperative planning is so high, that, together with the dental implants in the existing maxilla, and the dental implants in the graft, which provide additional stabilisation for the graft, a fixed bridge for the patient's dental restoration by using standard abutments can be constructed.

In some clinical cases stereolithographic models (Laserform®, Vienna) of both the maxilla with the defect and the donor site in the scapula have been produced for additional preoperative planning (not shown in detail). In each case a cephalometry X­ray analysis program was used and relevant gnathological parameters were transferred to 3D-CT visualization via graphic work station. With the same system radiological controls were carried out postoperatively.

Techniques of flap prefabrication and microsurgical reconstruction

The method presented is carried out in two steps: first the combined scapula flap is prefabricated, while 3-4 months later microsurgical reconstruction is performed. The prefabricated scapula flap and the microsurgical reconstruction in the maxillofacial area are presented schematically in Figs. 2b, 5a.

The prefabricated scapula flap (Fig. 2b)

Based upon preoperative analysis the appropriate part of the lateral border of the scapula is selected, freed from almost all tissues attached and osteotomised in the dimension required (Fig. 3a). The vascular bundle to the scapula is dissected in a distance of 2-3 cm and the implants (Brånemark-System® MK II - selftapping screws- dim. 3.75x10/13/15), placed into position as preoperatively planned (Fig. 3a). This bony piece, connected to the vascular bundle of the circumflex scapula vessels only (A. et. Vv. circumflexa scapulae) is then covered with split skin grafts, from which the superficial epidermal layers have been removed, and encapsulated with Goretex® 1 mm membranes (Fig. 3b). Muscles, subcutaneous tissue and skin are closed in layers, and this prefabricated flap is left in its position for three to four months.

Additionally, at the same time, the fixture placement of four implants (Brånemark-System® MK II - selftapping screws - dim. 3.75x10/13) into the existing right maxilla is performed.

Microsurgical reconstruction (Fig. 5a)

After this period, microsurgery in the maxillofacial region and the harvesting of the prefabricated scapula flap together with its vascular pedicle are performed by two teams in one go.

The Goretex®-membrane is removed. The cover screws of the implants are exposed by incision of the covering soft tissues and the incised margins retracted. A bone overgrowth is consistantly found and removed by using the cover screw mill. The cover screws are replaced by standard abutments 4 or 5mm (Fig. 4a).

Next the flap is transferred into the maxillofacial region (Fig. 5b). At this time the prefabricated scapula flap could be further combined with other scapula flaps for complex midface reconstruction19.

According to the preoperative planning the flap is first placed into the correct position (Fig. 5b). Stabilisation is achieved by using titanium miniplates and implants in combination with acrylic splints (the schematic drawing in Fig. 5a illustrates the flap fixation).

Vessels of the flap (A.et Vv. circumflexa scapulae) are reanastomosed with the facial vessels and the jugular vein (Fig. 5a). In adult cleft patients, where reconstruction takes place in the anterior part of the maxilla, venous grafts are used to lengthen the vascular pedicle.

After wound healing, performance of dental rehabilitation starts two to three weeks postoperatively with the removal of the acrylic splint (Fig. 7a) and is completed about four to six weeks later (Fig. 7b).

Histological Methods

From the harvested graft, still in its Goretex®-envelope, an about 3 mm wide prefabricated marginal part was trimmed away (Fig. 4b, dotted line), fixed in neutral buffered formaline, and embedded without decalcification in methyl-methacrylate. From the block, microtome and ground sections were prepared and evaluated by light microscopy after appropriate staining. For histochemical details see Plenk21.

Clinical and histological results

This new procedure was performed in a 51-year-old female patient with a hemimaxillectomy following resection of a protruding meningeoma of the skull base 13 years earlier (Figs.1a, 1b).

Flap prefabrication was performed as described above and harvested after four months.

The split skin graft was attached to the bone and showed macroscopically a mucosa-like structure (Fig. 4a). The implants were found stably anchored in the scapula flap (Fig. 4a).

The marginal portion of the flap, which was trimmed away before fitting in (Fig. 4a), showed that the split skin graft was attached to the vital scapula bone in a periostium-like manner and a small part of epidermis was visible, which showed the basal layers attached to the cutaneous papillae without keratinised cells (Fig. 4b). We can present evidence that the bone graft is vital and shows patterns of remodelling according to the degree the aereas of the flap are vascularised (not shown in detail).

The transplant healed nicely within a period of three weeks. Postoperative 3D-CT controls are shown in Figs. 6a and 6b. Secondary procedures for flap fitting, debulking of superfluous soft tissues and other preprosthetic surgery were not necessary (Fig. 7a). The surface of the split skin graft was macroscopically indistinguishable from the surrounding original oral mucosa (Figs. 7a, 7b).

The implants in a parallel position (Fig. 6b) then served for dental rehabilitation by a fixed bone anchored bridge in the reconstructed maxilla (Fig. 7b).

Discussion

Two methods of rehabilitating patients with big maxillofacial defects are common.

The prosthetic rehabilitation by implant retained prosthesis9,20, and the reconstruction by osseous, osteocutaneous and osteomyocutaneous flaps4,5,11,13,16,19,23,24,27.

In the midface region in particular, with its subtle bony and soft tissue structures, where both approaches are suitable and can be combined, the degree to which either one or the other method should be used must be carefully balanced out.

Myocutaneous flaps are often too bulky to fit pneumatised cavities, besides they limit oral function. This may lead to a preference for facial prostheses.

Apart from the microsurgical methods quoted above, other surgical techniques which are much cheaper and just as effective in reconstructing the maxilla have therefore been established and further improved for minor and medium-sized maxillofacial defects: The temporalis myo-osseous flap3, sagittal split temporalis myofascial flap with titanium mesh and free autogenous corticocancellous bone26, improvement of versatility of the temporal muscle by maximum dissection of the muscle and by removal of all connections to the scull base and masseter muscle allowing a "wrap around" technique14.

For more serious maxillofacial defects, a sophisticated method of reconstruction is required. Depending on comprehensive preoperative planning, so as to define all relevant anatomical and functional parameters before surgery, reconstruction by prefabricated composite grafts could be a new approach towards solving some of the problems.

As demonstrated above and in accordance with other authors, the scapula flap fits precisely into a maxillary defect7,13,24. If an improved flap design of the prefabricated composite scapula flap is provided, stable bone anchored implants which are used for both, flap fixation and dental rehabilitation and a thin soft tissue lining similar to the surrounding oral mucosa after wound healing can be performed.

Concerning the most suitable transplants for replacing oral mucosa, different surgical approaches have been discussed. Among them Reuther's,22 using revascularized jejunum transplants, was the first and has become a widely accepted technique. Hillerup17 published the results of his long term follow-up studies concerning the behavior of skin and mucosal grafts in vestibuloplasty: The biologic properties of skin transplanted to the oral cavity are less optimal then those of oral mucosa in terms of reaction to dental trauma and candida infection. In preprosthetic surgery transplanted cheek mucosa even tends to take on the histological appearance of the mucosa normally present on the edentulous alveolar ridge6. However the potential amount of oral mucosal graft material is the limiting factor for its use in mayor oral reconstruction. Moreover, they have to be grafted onto myoosseous or myoosteocutaneous flaps in the newly-built oral cavity - a complicated procedure, so that the grafting is more often than not performed at a later stage10,15,18. Yet there is an almost unlimited supply of split skin grafts, which retain their characteristics intraorally. They change only to a mucosa-like structure by repeated candida infections, which, at the onset, show a speckled pattern of atrophic, reddened epithelium, alternating with patches of apparently normal keratinised skin, leading to a "mucosalisation" of the whole skin graft as a result of the complete loss of keratinisation17.

This was not observed in any of our cases, for candida infections appear mainly in patients with systemic and local tumor associatedimmunodeficiencies screened by immunodiagnostic methods, and alcohol/ nicotin associated malnutrition syndrome28-32, all of which are prohibitive risk factors for complex microsurgery.

During flap prefabrication superficial keratonised layers of the split skin graft are removed, then the graft is attached to the bone, and left in close contact with a Goretex®-membrane envelope for three to four months. When the flap has been harvested and used for reconstruction, the split skin graft is macroscopically indistinguishable from the surrounding oral mucosa.

First results from an ongoing histomorphological evaluation of these prefabricated composite flaps give evidence that the bone graft is vital and extensively remodelling. Osseointegration of inserted implants is given (data not shown). The split skin graft is attached in a periostium-like manner to the remodelling bone. Basal parts of the epidermis without keratonised cells are attached to a papillary connective tissue layer. Those results might correlate with the macroscopic appearance of the skin in Figs. 7a and b.

The presented surgical concept is very comprehensive and requires equipment of the highest technical standard. For this reason, its application is mainly justified in such cases where other surgical methods quoted above have proved unsuccessful.

Nevertheless, there are considerable advantages of prefabricated composite scapula flaps:

  1. The method results in a higher precision of reconstructive surgery due to an improved flap design.
  2. Availability of osseointegrated implants at the time of microsurgical reconstruction, which can be used for both, flap fixation, and dental rehabilitation only few weeks postoperatively.
  3. Thin soft tissue linings without long lasting inflammation and granulation around the implant posts can be observed within a short postoperative period.
  4. Elimination of the spatial problem when microsurgery and reconstructive surgery are performed simultaneously, due to the improved managability of the flap on the one hand, and the minimizing of titanium miniplate osteosynthesis by use of implants for additional flap fixation on the other.

The prefabricated composite scapula flap comprises all components of the maxillofacial region to be reconstructed: bony flap, soft tissue lining, implants, vascular bundle etc. Microsurgical reconstruction is possible without major modifications of the composite flap during surgery.

Legends to figures

Pictures are available on request kurt.vinzenz@vienna.at

Fig. 1a: Conventional CT scan slice of the 51-year-old female patient, after hemimaxillectomy on the left side 13 years earlier.
Fig. 1b: 3D-CT visualisation of the maxilla in an axial direction.
Fig. 2a: 3D-CT visualisation of thoracic vertebrae, ribs and the left scapula after interactive manipulation of CT data: In this area the scapula offers favourable bony dimensions for implant placement.
Fig. 2b: Schematic drawing of the flap design: vascular bundle - A.V. circumflexa scapulae; bone - lateral border and corpus scapulae; soft tissue - split skin graft; dental implants - Brånemark-System®; Goretex® 1 mm membrane.
Fig. 3a: Implant bed preparation in the osteotomised and pedicled scapula before Brånemark® fixture installation.
Fig. 3b: The prefabricated pedicled scapula flap covered with Goretex®-membrane before being harvested / transferred and buried at the donor site.
Fig. 4a: The harvested prefabricated scapula flap after removal of the Goretex®-cover before transfer: The vascular pedicle, the Brånemark® implants with titanium standard abutments and impression copings, and the soft tissue lining adherent to the bone. The dotted line indicates for example a marginal portion before trimming.
Fig. 4b: Ground section (Giemsa stain), of a marginal portion of the prefabricated scapula flap with the Goretex®-cover (GM), magnification fifteen times. The split skin graft (SSG) is firmly attached to the bone, showing vital periosteal and endosteal remodelling. On the right partly detached, epidermis (ED) can be seen.
Fig. 5a: Schematic drawing of the prefabricated scapula flap and the microsurgical reconstruction in maxillectomy patients.
Fig. 5b: Reconstruction of the maxilla: Intraoperative situation before flap fixation by a methacrylat splint and titanium miniplate osteosynthesis. The view into the newly-built left maxillary sinus shows the soft tissue lining.
Fig. 6a: Postoperative radiological controls, 3D-CT visualisation in an axiocaudal view: The alveolus and palate reconstructed by prefabricated scapula flap.
Fig. 6b: The lateral border of the scapula is seen with osseointegrated implants in a parallel position to each other and to the implants in the right maxilla.
Fig. 7a: The soft tissue lining of the composite scapula flap can hardly be distinguished from the surrounding oral mucosa three weeks postoperatively. (Note the slight mucosal irritation after removal of splint).
Fig. 7b: Bridge anchored to the endosteous osseointegrated implants in the flap region after eight weeks (left side); a mucosa-supported prosthesis on the intact right side is retained by ball attachments.

 

References

  1. ALTOBELLI DE, KIKINIS R. MULLIKEN JB, CLINE H, LORENSEN W, JOLESZ F. Computer assisted three-dimensional planning in craniofacial surgery. Plast. Reconstr. Surg. 1993: 92/4: 576-586.
  2. ANDERSSON JE. CT- scanning in the preoperative planning of osseointegrated implants in the maxilla. Int. J. Oral Maxillofac. Surg.1988: 17: 33-37.
  3. ANTONYSHYN O, COLCLEUGH RG, HURST LN, ANDERSON C. The temporalis myo-osseous flap: An experimental study. Plast. Reconstruct. Surg. 1986: 77: 406-412.
  4. BOYD JB, ROSEN I, ROTSTEIN L, FREEMAN JG, MANKTELOW R, ZUKER R. The iliac crest and the radial forearm flap in vascularized oromandibular reconstruction. Am. J. Surg. 1990: 159: 301-316.
  5. DANIEL RK. Mandibular reconstruction with free tissue transfers. Ann. Plast. Surg. 1978: 1: 346-351.
  6. DEKKER JG, TIDEMANN H. Histologic study of a free mucosal graft from the cheek used in preprosthetic surgery. Int. J. Oral Surg.1973: 2: 284-296.
  7. DOS SANTOS LF. The vascular anatomy and dissection of the free scapular flap. Plast. Reconstr. Surg. 1984: 73:599-610.
  8. ELLIOT HR, NORRIS MS, ROSEN JM. Application of high tech three dimensional imaging and computer generated models in complex facial reconstructions with vascularised bone grafts. Plast. Reconstr. Surg: 91/2: 252-258.
  9. ERIKSSON E, BRÅNEMARK PI. Osseointegration from the perspective of the plastic surgeon. Plast. Reconstr. Surg. 1994: 93/3: 626-637.
  10. EWERS R, HOFFMEISTER B. Wiederherstellung der Prothesenfähigkeit im Unterkiefer nach Tumoroperationen. In: NEUBAUER H: Plastische und Wiederherstellungschirurgie des Alters. Springer, Berlin, Heidelberg, NY, London, Paris, Tokyo 1986: 215-121.
  11. FLEMMING AFS, BROUGH MD, EVANS ND, GRANT HR, HARRIS M, JAMES DR, LAWLOR M, LAWS IM. Mandibular reconstruction using vascularised fibula. Br. J. Plast. Surg.: 1990: 43: 403-409.
  12. FRODEL JL, FUNK GF, CAPPER DT, FRIDRICH KL, BLUMER JR, HALLER JR, HOFFMAN HT. Osseointegrated implants: A comparative study of bone thickness in vascularised bone flaps. Plast. Reconstr. Surg. 1993: 93/3: 449-456.
  13. GILBERT A, TEOT L, The free scapular flap. Plast. Reconstr. Surg. 1982: 69: 601-615.
  14. GRÄTZ KW, SAILER HF. Improvement of versatility of the temporal muscle and fascial flaps in maxillofacial reconstructive surgery. J. Cranio Max-Fac. Surg. 1994: 22/Suppl 1: 23.
  15. HÄRLE F, Ed.: Atlas der Präprothetischen Operationen, Vestibulumplastik nach Tumoroperationen 1989: 68-70.
  16. HIDALGO DA. Aesthetic improvements in free-flap mandible reconstruction. Plast. Reconstr. Surg. 1991: 88: 574-581.
  17. HILLERUP S. Preprosthetic mandibular vestibuloplasty with buccal mucosal grafts. A 2-year follow-up study. Int. J. Oral Surg.1982: 11:81-88.
  18. HOFFMEISTER B, EWERS R. Operative Maßnahmen zur Verbesserung des Prothesenlagers nach Tumoroperationen. Dtsch Zahnärztliche Z 1986: 41: 1207-1213.
  19. HOLLE J, VINZENZ K, WÜRINGER E, KULENKAMPFF KJ, SAIDI M. The combined scapula flap for bony and soft tissue reconstruction in extensive maxillofacial defects. Plast. Reconstr. Surg. 1996: in press.
  20. NEUKAM FW. Functional and esthetic rehabilitation with Brånemark implants following oncologic surgery. In: ALBREKTSSON T, ZARB GA. eds.: The Brånemark osseointegrated implant. Chicago, Quintessence, 1989b, 211-219.
  21. PLENK H. Jr., The microscopic evaluation of hard tissue implants. In: Techniques of biocompatibility testing, Vol.1; Ed.: DF Williams. CRC Press, Boca Raton, Florida, 1986: 35-81.
  22. REUTHER JF. Die chirurgische Therapie der Karzinome im Bereich der kaudalen Mundhöhle. In: VINZENZ KG, WACLAWICZEK HW. Eds: Die chirurgische Therapie von Kopf- Halstumoren. Wien, New York, Springer Verlag, 1992: 57-71.
  23. RIEDIGER D. Restoration of masticatory function by microsurgically vascularised iliac crest bone grafts using enosseous implants. Plast. Reconstr. Surg. 1988: 81: 861-869.
  24. SWARTZ WM, BANIS JC, NEWTON ED, RAMASASTRY SS, JONES NF, ACLAND R. The osteocutaneous scapular flap for mandibular and maxillary reconstruction. Plast. Reconstr. Surg. 1986: 77: 530-538.
  25. TAYLOR GI. Reconstruction of the mandible with free composite iliac bone grafts. Ann. Plast. Surg. 1982: 9: 362-369.
  26. TIDEMANN H.. Functional reconstruction following maxillectomy. J. Cranio-Max-Fac. Surg. 1994: 22/ Suppl. 1: 76.
  27. VAREMCHUC MJ. Vascularized bone grafts for maxillofacial reconstruction. Clin. Plast. Surg. 1989: 16: 29-38.
  28. VINZENZ K, MICKSCHE M. Systemic and regional natural cytotoxicity in patients with head and neck cancer. J. Max. Fac. Surg. 1986: 14: 251-300.
  29. VINZENZ K, PAVELKA R, SCHÖNTHAL E, ZEKERT F, Serum immunglobulin levels in patients with head and neck cancer. Oncology 1986:43: 316-322.
  30. VINZENZ K, PAVELKA R, SCHÖNTHAL E, ZEKERT F. Transportproteine für Vitamin A: Retinol Binding Protein (RBP) und Präalbumin (PA) im Serum von Patienten mit Mundhöhlenkarzinomen. Dtsche. Z. Mund-Kiefer-Gesichtschir.1986: 10: 199-205.
  31. VINZENZ K, SCHÖNTHAL E, ZEKERT F, WUNDERER S. Diagnosis of head and neck carcinomas by means of immunological tumor markers. J. Cran. Max. Fac. Surg. 1987: 15: 270-277.
  32. VINZENZ K, MICKSCHE M. Natural cytotoxicity in draining lymph nodes of squamous cell cancer in the maxillofaciol region. J. Oral Maxillofacial Surg.1987: 45: 42-47.