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Proplast, a porous implant for contour restoration
British ~oumol of Plastic Surgery (197(i), 29, 158-164
PROPLAST;
A POROUS
IMI’LM
FOR CONTOUR
By BROMLEY S. FREEMAN, M.D.,
RESTORATION
2
F.A.C.S.
Department of Plastic Surgery, Baylor College of Medicine, Houston, Texas and 1770 Doctors Center, Houston, Texas 77025, USA
PROPLA~T is a grey-black felt made from carbon fibres and Teflon, which was first prepared by Homsy (1970). It has more than 75 per cent porosity and the gaps between the fibres range from 200 to 500 microns (Fig. I); cells and new blood vessels can easily pass through to be followed by fibrous tissue and thereafter firm fixation of the implant to its environment. The ingredients were selected to satisfy 3 main criteria: biocompatibility, thermostability and surface energy characteristics which would not damage absorbed elements. In addition, an attempt was made to make the modulus of the material approach that of soft tissue. It can be easily carved with a knife. EXPERIMENTAL OBSERVATIONS Over a d-year period, the behaviour of small pieces of Proplast inserted sub- and supraperiosteally on the facial bones of baboons has been studied. A full report will be published elsewhere but the following is a summary of the main points: All implants remained stable as to site, size and shape. All of them felt firmer than subcutaneous tissue but not bone-hard. Many multinucleated giant cells were present in and around the implant from an early stage. Fibrous tissue ingrowth slowly increased. Early osteoid formation in subperiosteally placed implants did not increase with time. All the long-term subperiosteal implants produced absorption in the underlying bone and depressions 2 to 5 mm deep; the implants had to be removed forcibly and left a bleeding cavity behind. The supraperiosteal implants left a smooth non-bleeding surface behind, sometimes slightly depressed but by not more than 0.5 mm. Proplast would therefore seem to be a suitable implant material for clinical use and has all the criteria we have required in the past (Freeman et al., 1965) with the exception of not having a consistency similar to the surrounding soft tissues. It approaches, however, the consistency of bone and should be suitable for contour restoration of bony depressions so long as it is inserted outside the periosteum. CLINICALEXPERIENCE Although Proplast was initially used as a coating for metal prostheses to allow them to be fixed to bone or other tiSSUeS(Homsy et al., 1972, 1973; Homsy, 1973), I am concerned here with the implantation of the material alone and have progressed from 1Made by Vitek Inc.,
3143 Yellowstone Street, Houston, Texas 77054, USA. * Presented at the American Association of Plastic Surgeons’ Meeting, 28th April 1975.
158
PROPLAST,
A POROUS
FIG. I.
FIG.
2.
IMPLANT
FOR CONTOUR
A piece of Proplast
magnified
IOO
RESTORATION
times.
Patient with microgenia overcorrected by PropIast implant; secondary revision at 4 months. A, Preoperative.
159
160
BRITISH
JOURNAL
OF PLASTIC
SURGERY
FIG. z. B, Implant sculptured, contrasted with commercial, solid, Silastic implant. C, Insertion through skin incision. Fixation by supraperiosteal suture. D, Four months postoperative with obvious overcorrection. E, Final result. Implant has now been in place for 4 years.
PROPLAST,
FIG. 3.
A POROUS
IMPLANT
Insertion of Proplast implant intra-orally patient’s blood, positioned via intra-oral
2912-D
FOR CONTPUR
RESTORATION
for microgenia. A, Carved implant injected B & C, 6 months postoperative. incision.
x61
with
162
BRITISH
JOURNAL
OF PLASTIC
SURGERY
FIN G. 4. Pectus excavatum corrected by the insertion of 3 large pieces of Proplast. A, Preoperati% re. B, Eight months postoperative prior to augmentation mammaplasty when a biopsy of the Proplast w as obtained.
PROPLAST,
A POROUS
FIG. 5. Biopsy of one of the implants cell reaction around the implant.
IMPLANT
,FOR
CONTOUR
RESTORATION
163
inserted in the case shown in figure 4. A, Multinucleated giant B, One of the cells showing ingestion of carbon fragments.
164
BRITISH
JOURNAL
OF PLASTIC
SURGERY
the use of small implants in microgenia (Figs. 2 and 3) and other facial bone depressions to very large implants in 3 cases of pectus excavatus (Fig. 4). Proplast can be bonded readily to other materials and I have used a thin layer bonded to a sheet of Teflon with the smooth surface directly under the skin of the nasal bridge and another to provide skin mobility after excising adherent scars on the chin. Proplast, bonded to a Silastic envelope for augmentation mammaplasty, and a penile implant have been designed but not yet used.
RESULTS
There was only I infection among 26 supraperiosteal implants and this required removal of the implant. Otherwise the results have been satisfactory. One or two have had to be trimmed secondarily; virtually no moulding or change in shape occurs biologically after implantation and the initial sculpturing must be precise. So far there has been no sign of bone absorption. The Proplast is well tolerated in the tissues, becomes fixed and firm within 6 weeks and open and needle biopsies have shown no tissue reaction other than the multinucleated “foreign body” giant cells. Two of the 3 massive sternal implants had an initial period of serum formation, lasting 3 weeks in I and 2 weeks in another, but are now firm and secure and have been followed for 12 and g months respectively. An augmentation mammaplasty in the latter allowed examination and a biopsy of the implant and its bed (Fig. 5). The grey-black colour of the material is not seen when the skin covering is thicker than 0.5 mm, but it has been seen under thin eyelid skin where the absence of subcutaneous tissue has caused an eyelid to become adherent to the upper surface of the Proplast in 2 patients. In this region a composite Teflon Proplast prosthesis should be considered. To date, all patients have accepted a Proplast implant as part of their body image, probably because of its immobility and the absence of a palpable join. How the implant will react to external trauma, whether mechanical or thermal, acute or chronic, has yet to be determined and patients must be cautioned against this risk. REFERENCES
FREEMAN,B. S., BIGGS,T. M. and BEALE,A. C., Jr. (1965). Injectable Silastic in deformities of the facial skeleton. Archmes of Surgery, 90, 166. HoMSY, C. A. (1970). Bio-compatibility in selection of materials for implantation. _?ournaE ofBiomedical Materials Research, 4, 341. HOMSY, C. A. (1973). Implant stabilization-chemical and biochemical considerations. Orthopedic Clinics of North America,
HOMSY, C. A., CAIN, T. E., Porous implant systems Research, 89, 220. HOMSY, C. A., KENT, J. N. biological and functional
4, 295.
KESSLER,F. B., ANDERSON,M. S. and KING, J. W. (1972). for prosthesis stabilization. Clinical Orthopedics and Related and HINDS, E. C. (1973). Materials for oral implantationcriteria. Journal of the American Dental Association, 86, 817.
PROPLAST;
A POROUS
IMI’LM
FOR CONTOUR
By BROMLEY S. FREEMAN, M.D.,
RESTORATION
2
F.A.C.S.
Department of Plastic Surgery, Baylor College of Medicine, Houston, Texas and 1770 Doctors Center, Houston, Texas 77025, USA
PROPLA~T is a grey-black felt made from carbon fibres and Teflon, which was first prepared by Homsy (1970). It has more than 75 per cent porosity and the gaps between the fibres range from 200 to 500 microns (Fig. I); cells and new blood vessels can easily pass through to be followed by fibrous tissue and thereafter firm fixation of the implant to its environment. The ingredients were selected to satisfy 3 main criteria: biocompatibility, thermostability and surface energy characteristics which would not damage absorbed elements. In addition, an attempt was made to make the modulus of the material approach that of soft tissue. It can be easily carved with a knife. EXPERIMENTAL OBSERVATIONS Over a d-year period, the behaviour of small pieces of Proplast inserted sub- and supraperiosteally on the facial bones of baboons has been studied. A full report will be published elsewhere but the following is a summary of the main points: All implants remained stable as to site, size and shape. All of them felt firmer than subcutaneous tissue but not bone-hard. Many multinucleated giant cells were present in and around the implant from an early stage. Fibrous tissue ingrowth slowly increased. Early osteoid formation in subperiosteally placed implants did not increase with time. All the long-term subperiosteal implants produced absorption in the underlying bone and depressions 2 to 5 mm deep; the implants had to be removed forcibly and left a bleeding cavity behind. The supraperiosteal implants left a smooth non-bleeding surface behind, sometimes slightly depressed but by not more than 0.5 mm. Proplast would therefore seem to be a suitable implant material for clinical use and has all the criteria we have required in the past (Freeman et al., 1965) with the exception of not having a consistency similar to the surrounding soft tissues. It approaches, however, the consistency of bone and should be suitable for contour restoration of bony depressions so long as it is inserted outside the periosteum. CLINICALEXPERIENCE Although Proplast was initially used as a coating for metal prostheses to allow them to be fixed to bone or other tiSSUeS(Homsy et al., 1972, 1973; Homsy, 1973), I am concerned here with the implantation of the material alone and have progressed from 1Made by Vitek Inc.,
3143 Yellowstone Street, Houston, Texas 77054, USA. * Presented at the American Association of Plastic Surgeons’ Meeting, 28th April 1975.
158
PROPLAST,
A POROUS
FIG. I.
FIG.
2.
IMPLANT
FOR CONTOUR
A piece of Proplast
magnified
IOO
RESTORATION
times.
Patient with microgenia overcorrected by PropIast implant; secondary revision at 4 months. A, Preoperative.
159
160
BRITISH
JOURNAL
OF PLASTIC
SURGERY
FIG. z. B, Implant sculptured, contrasted with commercial, solid, Silastic implant. C, Insertion through skin incision. Fixation by supraperiosteal suture. D, Four months postoperative with obvious overcorrection. E, Final result. Implant has now been in place for 4 years.
PROPLAST,
FIG. 3.
A POROUS
IMPLANT
Insertion of Proplast implant intra-orally patient’s blood, positioned via intra-oral
2912-D
FOR CONTPUR
RESTORATION
for microgenia. A, Carved implant injected B & C, 6 months postoperative. incision.
x61
with
162
BRITISH
JOURNAL
OF PLASTIC
SURGERY
FIN G. 4. Pectus excavatum corrected by the insertion of 3 large pieces of Proplast. A, Preoperati% re. B, Eight months postoperative prior to augmentation mammaplasty when a biopsy of the Proplast w as obtained.
PROPLAST,
A POROUS
FIG. 5. Biopsy of one of the implants cell reaction around the implant.
IMPLANT
,FOR
CONTOUR
RESTORATION
163
inserted in the case shown in figure 4. A, Multinucleated giant B, One of the cells showing ingestion of carbon fragments.
164
BRITISH
JOURNAL
OF PLASTIC
SURGERY
the use of small implants in microgenia (Figs. 2 and 3) and other facial bone depressions to very large implants in 3 cases of pectus excavatus (Fig. 4). Proplast can be bonded readily to other materials and I have used a thin layer bonded to a sheet of Teflon with the smooth surface directly under the skin of the nasal bridge and another to provide skin mobility after excising adherent scars on the chin. Proplast, bonded to a Silastic envelope for augmentation mammaplasty, and a penile implant have been designed but not yet used.
RESULTS
There was only I infection among 26 supraperiosteal implants and this required removal of the implant. Otherwise the results have been satisfactory. One or two have had to be trimmed secondarily; virtually no moulding or change in shape occurs biologically after implantation and the initial sculpturing must be precise. So far there has been no sign of bone absorption. The Proplast is well tolerated in the tissues, becomes fixed and firm within 6 weeks and open and needle biopsies have shown no tissue reaction other than the multinucleated “foreign body” giant cells. Two of the 3 massive sternal implants had an initial period of serum formation, lasting 3 weeks in I and 2 weeks in another, but are now firm and secure and have been followed for 12 and g months respectively. An augmentation mammaplasty in the latter allowed examination and a biopsy of the implant and its bed (Fig. 5). The grey-black colour of the material is not seen when the skin covering is thicker than 0.5 mm, but it has been seen under thin eyelid skin where the absence of subcutaneous tissue has caused an eyelid to become adherent to the upper surface of the Proplast in 2 patients. In this region a composite Teflon Proplast prosthesis should be considered. To date, all patients have accepted a Proplast implant as part of their body image, probably because of its immobility and the absence of a palpable join. How the implant will react to external trauma, whether mechanical or thermal, acute or chronic, has yet to be determined and patients must be cautioned against this risk. REFERENCES
FREEMAN,B. S., BIGGS,T. M. and BEALE,A. C., Jr. (1965). Injectable Silastic in deformities of the facial skeleton. Archmes of Surgery, 90, 166. HoMSY, C. A. (1970). Bio-compatibility in selection of materials for implantation. _?ournaE ofBiomedical Materials Research, 4, 341. HOMSY, C. A. (1973). Implant stabilization-chemical and biochemical considerations. Orthopedic Clinics of North America,
HOMSY, C. A., CAIN, T. E., Porous implant systems Research, 89, 220. HOMSY, C. A., KENT, J. N. biological and functional
4, 295.
KESSLER,F. B., ANDERSON,M. S. and KING, J. W. (1972). for prosthesis stabilization. Clinical Orthopedics and Related and HINDS, E. C. (1973). Materials for oral implantationcriteria. Journal of the American Dental Association, 86, 817.