Queen Mary's Hospital, Roehampton, Londcn

Transcription

1 A UNIVERSAL KIT IN TITANIUM FOR IMMEDIATE REPLACEMENT OF THE RESECTED MANDIBLE JOHN E. BOWFaMA~, M.B., Ch.B., B.D.S., F.D.S.R.C.S., and BRIAN CONROY, L.I.B.S.T. Queen Mary's Hospital, Roehampton, Londcn THE need for a simple, adaptable form of lower jaw replacement has been felt for a considerable time, to overcome the problem which frequently arises when one is asked: 'Can you come and put something in? We are resecting part of a mandible tomorrow.' When faced with this situation, the best that one can usually manage is to impact or screw a Knowles pin or similar bar into the mandibular canal or a tunnel drilled in the medullary bone. These efforts are doomed to FIG. I The complete set of sectional implants. failure even as a temporary measure, because one or both ends usually slip out when the patient recommences active jaw movement. We felt that one should be able to offer something more constructive and reliable when called upon to help at short notice. We have designed a range of sectional implants which can be purchased from the instrument makers. These can be assembled and inserted in theatre to bridge any mandibular defect without obtaining pre-operative measurements. Our previous experience with implant materials shows that Titanium I3o and I6o fulfil 223

2 ~!ii~i~ ~... ~ii~:; / e" Z 0 a! ; 7,.! D FIG. e Diagrams illustrating the desirable location of implants to facilitate soft tissue closure. A, Stippled area represents the space saved by lingual application. B, Additional area (hatched) gained by collapsing the mandibular fragments. C and D, Position in vertical and horizontal planes. Fie. 3 The instruments required for the fabrication and fixation of implants.

3 A UNIVERSAL KIT IN TITANIUM 225 the requirements for this type of prosthesis. We consider these to be: simple design, versatility, straightforward adaptation and insertion, adequate strength, tissue inertness and availability from stock. The purpose of this preliminary communication is to describe the essential components, illustrate the practical application of the working tools and outline two case reports. A subsequent paper will describe in detail the research and technology which preceded the development of this kit. FIG. 4 The application of the working tools. A, Bar bender for contouring the intermediate bar of body sections. B, Plate benders for adjusting the fixation plates of body sections. C, The application of the drilling jig to align the bolt holes. D, The riveting tool in use for joining a ramus and body section by means of screw rivets. THE ESSENTIAL COMPONENTS It may be helpful to explain briefly how the various parts have been adapted to practical considerations (Fig. I). The body sections are made of Titanium 13o; this has been found sufficiently malleable to allow bending in theatre to the desired shape. They are designed to be fitted to the lingual aspect of the mandible to facilitate closure of the soft tissue layers without tension over the prosthesis. The excision of soft tissue in the floor of the mouth may impede their approximation; this difficulty can be increased when the implant is fitted to the buccal aspect. Lingual application can effect sufficient saving of tissue space to allow a satisfactory closure (Fig. 2, A); the gap may be further reduced by collapsing the mandibular fragments (Fig. 2, B).

4 226 BRITISH JOURNAL OF ORAL SURGERY The ramus and angle sections are made ill Titanium 16o; this gives maximum strength and allows appropriate holes to be tapped where riveting and screw pins are required. The varying lengths and inclination of the angle and ramus sections (which can be used on either side) allow location in a central position in the vertical and horizontal planes (Fig. 2, c and I)). This feature, together with lingual fixation, also facilitates approximation of the soft tissues without appreciably FIG. 5 A selection of fabricated implants. A, Body section restoring a central mandibular defect. B, Restoration of a resection involving the angle of the mandible. A screw pin has been inserted through the upper tapped hole of the angle section. C, Hemi-mandibular implant. D, Complete mandibular implant. effecting the ultimate contour of the jaw. The pressure on the overlying skin is also reduced and this may prevent ulceration when there has been gross sacrifice of soft tissue. Finally, the Wilson spinal bolts have been modified to incorporate a slot in the bolt head for the use of a screwdriver. The application of the riveting and screw pins will be demonstrated later in the paper. PRE-OPERATIVE REQUIREMENTS We wish to re-emphasise at this point that no pre-operative measurements are essential when using this kit. Any mandibular resection can be replaced by choosing appropriate sections and riveting them together in theatre. However,

5 A UNIVERSAL KIT IN TITANIUM 227 if time permits, a simple plaster model of the teeth or alveolar ridge cast from a lower impression, together with a true lateral and submento-vertex radiograph of the mandible taken at a 6-ft. anode-film distance, will allow pre-operative selection and fabrication of a suitable implant. If at operation it should be found necessary to resect more bone than had originally been planned, a longer body section can be chosen and adjusted in theatre to the required contour. THE PRACTICAL APPLICATION OF THE WORKING TOOLS The working tools required for contouring and uniting appropriate sections and fixing the implant to the mandible are illustrated (Fig. 3). FIG. 6 The implant (Case I) bolted to the lingual aspect of jaw. The recesses cut with vulcanite burs for the fixation plates should be noted. The body sections are bent to the desired shape with the bar and plate benders (Figs. 4, A and B). The drilling jig is used to align accurately the bolt holes in the mandible with the fixation plates of the body sections (Fig. 4, c) because freehand drilling can lead to poor alignment of the second bolt hole. Screw rivets can be threaded through the tapped holes of the ramus and angle sections to unite them with a selected body section by means of the riveting tool (Fig. 4, D). In this way, appropriate implants can be fabricated to restore varying mandibular defects (Fig. 5, A, B, C and 9). Access for drilling holes high up on the ascending ramus can present difficulties and may occasionally prevent insertion of a second bolt. The upper hole of the angle section is tapped to allow insertion of a screw pin to prevent rotation which would occur around the axis of a single bolt. Finally, the implant is fixed in position by means of the modified Wilson bolts. The nut is held on the lingual aspect by the nut-holding forceps and the bolt tightened by means of a screwdriver or box spanners.

6 228 BRITISH JOURNAL OF ORAL SURGERY CASE REPORTS Case x. A man aged 5o was admitted for urgent excision of a metastatic squamous carcinoma fixed to the mandible in the submental region. On the pre-operative evening, we were asked if we could stabilise the divided jaw. The relevant surgery involved a suprahyoid clearance with removal en bloc of the central mandible just anterior to the mental foraminae. A titanium body section was bent in theatre to the required shape. The lingual aspect of the mandible on each side was then recessed with a vulcanite bur to allow accurate seating of the retention plates. Finally, appropriate holes were drilled from the lingual aspect and the prosthesis bolted into the desired position (Fig. 6). FIG. 7 Reconstruction of the mandible (Case 2) by means of body and angle sections. Note the ends of the screw rivets have been turned over by the riveting tool to complete the junction. Post-operatively, the patient had a satisfactory range of jaw movement, acceptable facial contour and resumed his employment within two months. Case e. A female patient, aged 55, was admitted for excision of a recurrent adamantinoma which had invaded a bone graft of the left body of the mandible. At operation, the jaw was divided 2 cm. above the left angle and at the midline. The bony defect was measured and appropriate angle and body sections selected. The body section was bent to the required contour and then riveted to the angle section. The implant was then bolted to the outer aspect of the left ascending ramus and to the lingual surface of the jaw on the right side (Fig. 7). Post-operatively, the occlusion, jaw function and facial contour were satisfactory. ACKNOWLEDGEMENTS We wish to express our appreciation to Mr. R. Sutton Taylor for his enthusiastic advice and interest. Our thanks are also due to him and Mr. W. Holdsworth for inviting us to insert implants into their patients and granting permission to present the case reports. We are especially indebted to Mr. G. M. Down who has patiently helped us to produce the kit and working tools and to Mr. I. H. Heslop for his help with the preparation of the paper. Finally, our thanks to Dr. P. HanselI and Mr. E. Ferrill for the photography.