Late breast pain following reconstruction with polyurethane-covered implants

Two patients of 56 who were reconstructed with polyurethane-coated implants developed breast pain as a late complication and eventually required implant removal for relief. Although the cause of pain was not proven, it may have been due to contracture of the fibrous capsule which formed between the polyurethane and the shell of the implant. The complication of late pain has not been stressed previously in the literature on reconstruction.     

Ten-year review of a prospective randomized controlled trial of textured versus smooth subglandular silicone gel breast implants

Although textured silicone breast implants have been shown to reduce the incidence of capsular contracture, there is little evidence if this effect is maintained in the long term. It has been 10 years since the double-blind randomized trial in which 53 patients received either Mentor smooth (26) or textured silicone gel implants (27). Of the 14 patients who were not known to have developed a contracture in the smooth group, 11 were reviewed. Three had bilateral contractures. In the textured group, 18 of the 24 patients not known to have contractures were reviewed. None had developed contractures. At 10 years, the incidence of capsular contracture was 65 percent of patients with smooth implants (an increase of 6 percent on the 3-year results) and 11 percent for the textured implant patients (no change on the 3-year results). A database containing the details of 1100 patients reinforces these results by examining the differences in contracture rates of textured, smooth, and polyurethane-coated implants. The effect of submuscular placement on reducing contracture rates regardless of texturing is discussed, as is the apparent increase in capsular contracture in patients who smoke.     

What exactly was wrong with the Trilucent breast implants? A unifying hypothesis

Trilucent soybean oil-filled breast implants were initially announced as the ultimate prostheses for breast augmentation. However, after an increasing number of reports of local complications and hazardous metabolites attributable to lipid oxidation, first the United Kingdom Medical Devices Agency and later the Belgian National Ministry of Health urged all plastic surgeons to contact their patients and advise them to have the implants removed and, if desired, replaced with another type of prosthesis. In our plastic surgery department, 13 patients received bilateral implants with triglyceride-filled prostheses between February and July of 1996, for primary breast augmentation or replacement of previously implanted prostheses. For 12 of those 13 patients, the prostheses have been explanted, because of unilateral breast enlargement attributable to a ruptured prosthesis for five patients and following the recommendation of the Belgian National Ministry of Health for the other seven patients. Before explantation, all patients underwent standard clinical examinations, with assessments of breast shape, volume, and firmness. Blood analyses were performed, with a special focus on liver enzymes, as were urinalyses. Magnetic resonance imaging scans were obtained before explantation; for two patients, the scans revealed a fluid level separating two liquid layers in an intact prosthesis. This is the first report of such a finding. The removed implants were examined for any damage or shell deterioration and for changes in color and viscosity, the weights and volumes were measured and compared with the initial values for the implanted prostheses, and complete biochemical analyses of the accumulated fluid in cases of ruptured prostheses and of the filler material in cases of intact prostheses were performed. This small but well-documented series illustrates the multitude of problems associated with triglyceride-filled implants, including bleeding of the triglyceride filler; shell deterioration, as indicated by a loss of texture and extreme fragility of the implant (with rupture or delamination with a simple finger touch); an increase in osmotic pressure exerted by the degraded filler material; progressive weakening of the outer silicone shell, with influx of plasma proteins of up to 750 kDa, eventually resulting in rupture of the prosthesis; a lack of oxidative stability and the formation of toxic oxidation products; a lack of biocompatibility, with the formation of insoluble organic soap-like material; and a pronounced inflammatory reaction. It is concluded that the sequential and/or simultaneous occurrence of (1) implant bleeding, (2) lipid infiltration of the silicone elastomer, and (3) inflammation attributable to oxidation products provides an overall explanation or unifying hypothesis for the wide variety of adverse events related to soybean oil-filled implants.     

Treatment of midfacial defects using prostheses supported by ITI dental implants

The purpose of this study was to evaluate retrospectively the use of ITI dental implants used for anchoring facial prostheses in the restorative treatment of midface defects. The authors analyzed the clinical data of 26 patients with orbital defects (n = 11), orbitonasal defects (n = 4), orbitonasomaxillary defects (n = 3), and nasal defects (n = 8). Data included age, sex, primary disease, implant position, implant length, implant failure, prosthetic attachment, radiation therapy, and peri-implant skin reactions. Follow-up was at 1, 3, 6, and 12 months and then on a yearly basis. The authors noted the status of healing and complications, if any. In total, 62 implants were placed as follows: 27 (43.5 percent) for orbital prostheses, 12 (19.4 percent) for orbitonasal prostheses, 14 (22.6 percent) for orbitonasomaxillary prostheses, and nine (14.5 percent) for nasal prostheses. Thirty-eight implants (61.3 percent) were placed in previously irradiated areas in 18 patients (69.2 percent). Mild skin reactions together with mild accumulation of sebaceous crusting around implants were recorded in 14.2 percent of the skin observations. No patient experienced severe inflammation requiring administration of systemic antibiotics or surgical revision. Implant success was 100 percent in both irradiated and nonirradiated patients. In conclusion, ITI dental implants result in a high rate of success in retaining midface prostheses and offer good stability and aesthetic satisfaction.     

Long-term use of polyurethane breast prostheses: a 14-year experience

I have used polyurethane prostheses for the past 14 years, implanting 220 implants into 130 patients who desired breast reconstruction after subcutaneous mastectomy or cancer ablation or simply breast augmentation. I theorize that a polyurethane-covered implant resists contracture, retaining its compressibility because the fibroblasts proliferate into the polyurethane in many different directions. When the fibrils contract, the forces of contracture counterbalance one another, resisting contracture. However, when smooth prostheses are implanted, fibrils are directed in a circular fashion around the implant and naturally contract, leading to firmer breasts. There were 115 prostheses inserted following subcutaneous mastectomy, and 22 percent developed contracted capsules. Seven implants became exposed because of skin necroses; one was removed because of a Staphylococcus infection; and two patients developed a combination of polyurethane and silicone granulomas. These developed only with the earlier implant, where there was shedding of the polyurethane sponge layer and silicone bled from the low-viscosity silicone used in the earlier implants. No granulomas were noted with the currently used Surgitek Replicon implant. Eighty-five breasts were reconstructed after cancer ablation with polyurethane implants, and the contracture rate was 2.3 percent. Other complications were minimal. A smaller group of patients had augmentation mammaplasty, and 20 prostheses were placed in 10 patients. A 15 percent contracture rate was noted in this group. In this study, 82 percent of patients were followed for up to 14 years. Capsular contractures occurred in 30 implants between 1 and 11 years, for an average recurrence at 6.3 years. The overall contracture rate was 13 percent. Other complications were minimal. All implants were placed subcutaneously or subglandularly, and all were drained.     

Polyurethane implants: a 6-year review of 416 patients

The author reviews 6 years of experience and 416 patients in whom polyurethane implants were used for augmentation and reconstruction of the breast. As with many other plastic surgeons, early use was confined to "salvage cases." Owing to the impressive results, use was extended to routine augmentation. Polyurethane implants are now used exclusively for aesthetic breast surgery. Results are evaluated for replacement of gel capsules and simple and radical mastectomy reconstruction. Gel capsules (Baker stages III to IV), in which prostheses were removed and replaced with polyurethane-covered implants, improved in 29 of 32 patients (87 percent). For reconstruction, placement of polyurethane implants in unscarred situations gives far superior results than following repeated procedures. The incidence of infection is no higher than with gel implants. Removal without capsulectomy was not a problem in most instances. However, on two recent occasions capsulectomy was extremely difficult.     

Maxillary reconstruction with a fibula osteoseptocutaneous free flap and simultaneous insertion of osseointegrated dental implants

The fibula osteoseptocutaneous flap is a good option for reconstruction of three-dimensional composite maxillary defects. This flap provides both bone and soft-tissue reconstruction and allows osseointegrated dental implantation, either simultaneously or in a second-stage procedure. Simultaneous placement of osseointegrated dental implants reduces operative sessions and allows faster oral rehabilitation for properly selected patients. The defects may result from trauma or resection of benign tumors or low-grade malignancies. Between August of 1999 and July of 2001, three patients underwent maxillary reconstruction with the fibula osteoseptocutaneous flap and simultaneous osseointegrated dental implants. The cause of the defect was trauma in two cases and resection of an adenoid cystic carcinoma in the other. The mean length of the fibula used for bony reconstruction was 4.7 cm. One osteotomy was performed in one case and no osteotomy was necessary in the other two. Skin islands of 8 x 2.5 cm and 16 x 3.5 cm were used for two patients. For the other patient, a double skin island was used for both nasal (6 x 4 cm) and oral (6 x 5 cm) reconstructions. Two osseointegrated implants were inserted into the fibular bone for each patient. Six months after the first-stage procedure, palatal rotation flaps or mucosa grafts were used to cover the exposed implant necks and prepare the implants for prostheses. One month after the second-stage procedure, prostheses were placed. An implant-supported prosthesis was used for one patient and implant/tissue-supported prostheses were used for the others. At a mean follow-up time of 30 months (range, 16 to 38 months), all patients were able to use the dental prosthesis for chewing (beginning 6 weeks after the final procedure) and all patients were satisfied with the cosmetic results.     

Microbial growth in saline breast implants and saline tissue expanders

The subject of microbial growth within the saline medium of prosthetic breast implants has been one of great controversy in recent years. Although several articles have described microbial growth within the tissue surrounding implanted breast prostheses, few have attempted to determine the possibility of such contamination of the luminal saline. The authors studied the intraluminal saline medium of a series of explanted breast prostheses with the objective of identifying any microbial contamination. Over a 6-month period, a consecutive series of saline-filled breast implants and tissue expanders were removed from 37 patients. Under the supervision of a microbiologist, saline extracted from each implant was subjected to bacterial and fungal cultures, Gram staining, and acid-fast staining. A total of 24 saline-filled breast implants were removed from 15 patients, and 32 saline-filled tissue expanders were removed from 22 patients. The average length of implantation was 28.1 months for the implants and 7.1 months for the expanders. None of the saline within the implants or expanders within our series displayed any evidence of microbial contamination. These results suggest that microbial contamination of the luminal saline of prosthetic breast implants is an extremely unlikely event.     

Recurrence of subglandular breast implant capsular contracture: anterior versus total capsulectomy

The objective of this study was to determine whether the type of capsulectomy, anterior or total, affects the recurrence of capsular contracture around subglandular silicone-gel breast implants. A retrospective analysis was performed of patients who underwent either anterior or total capsulectomy for Baker grade 3 or 4 subglandular capsular contracture in our unit. All patients were invited to a review clinic where their capsular status was assessed. There were 100 anterior- disc capsulectomies in 60 patients between 1988 and 1997 and 99 total capsulectomies in 60 patients between 1990 and 1998. The follow-up in the former group was a median of 7 years and mean 6.9 years, compared with median 2.5 and mean 3.1 years in the latter group. Eighty-six percent of the implants removed from both groups at capsulectomy were smooth-walled gel-filled implants. Sixty-nine breasts in the anterior group received textured gel implants at capsulectomy; the remaining 31 received polyurethane-coated Meme implants. In the total capsulectomy group, all but two breasts (one patient) received textured gel implants. After review, the capsular status was known in 80 percent of the anterior and 92 percent of the total capsulectomy group. The review clinic found eight new contractures in five patients to have developed in the anterior compared with none in the total group. Recurrent contractures affected 50 percent of patients (46 percent of breasts) in the anterior and 11 percent of patients (10 percent of breasts) in the total capsulectomy group. Kaplan-Meier survival analysis was applied to the data. By including only patients who received textured gel implants at capsulectomy, the Logrank found a statistical difference between the two treatment groups (0.01 < p < 0.5). We believe that this study provides some evidence that total capsulectomy for subglandular silicone breast implant capsular contracture results in a lower capsular recurrence than anterior- disc capsulectomy. The pattern and risk of recurrence after total capsulectomy and exchange for a modern textured prosthesis appear to approach those following primary augmentation.     

Oral health and oral implant status in edentulous patients with implant‐supported dental prostheses who are receiving long‐term nursing care

Aim: The aim of this study was to investigate oral health and oral implant status in a group of edentulous patients receiving long‐term residential or nursing care (LTC), all of whom had implant‐supported fixed or removable dental prostheses. Material and methods: A dental examination was performed on a total of 3310 patients receiving LTC and from this population 35 edentulous patients in whom dental implants had been placed formed the cohort for this study. All examinations were performed by a specialist in hospital dentistry and took place in the patients’ own home environment. Oral health was assessed by means of a protocol which evaluated oral hygiene status, possible oral mucosal inflammation and oral mucosal friction levels. Any problems with the implant‐supported prosthesis, implant mobility or other complications were also assessed. In addition, patients were asked about any oral symptoms and their usual oral hygiene procedures. Results: About half of the subjects (17/35) were registered as having no/mild inflammation with 18 of 35 having moderate/severe inflammation. Twelve of the 35 patients had good/acceptable oral hygiene and 23 of 35 had poor/bad oral hygiene. Twenty‐one of the 35 patients depended on help from the nursing personnel for their daily oral hygiene procedures. Obvious problems with food impaction were noted in 11 patients. A total of 229 implants had been placed in 43 jaws supporting 40 full arch‐fixed prostheses and three implant‐borne overdentures. There was no evidence of mobility or fractures of either the implants or the prostheses. Fifteen implants showed some exposed screw threads. Pus was exuding from one implant site and general peri‐implant gingival hyperplasia was noted in two patients. Twenty‐four patients were completely satisfied with the function and appearance of their implant‐supported prostheses. Two patients were totally dissatisfied. Conclusion: This study indicates that oral implant therapy can be considered as a treatment of choice in elderly patients, even if oral hygiene is sub‐optimal.     

The management of anterior chest wall deformity in patients presenting for breast augmentation

Anterior chest wall asymmetry is sometimes encountered in patients presenting for consideration of breast augmentation. The chest wall asymmetry or deficiency may be significant enough to consider reconstruction at the same time as breast augmentation in a small number of cases. Customized and prefabricated chest wall implants have been used in a variety of conditions including Poland syndrome, pectus excavatum, and sunken anterior chest. Careful moulage preparation and on-table implant modification are needed to "seat" these implants on the skeletal chest wall under the pectoralis major muscle. The chest wall implant provides a base for the subsequent breast prostheses and fills up a bony deficit that cannot be camouflaged by the breast prostheses alone.     

Capsular contracture around saline-filled fine textured and smooth mammary implants: a prospective 7.5-year follow-up.

In a previous prospective randomized clinical study comparing in the same patient textured and smooth saline-filled mammary implants (Biocell) with large pore size (300 to 600 microm), we saw no difference in capsular contracture. This study was undertaken in a similar way to compare capsular contracture around smooth and textured saline-filled prostheses with pores of small size. During a period of 7.5 years, the breast hardness was followed up, and at the end of the study patient satisfaction was evaluated.Twenty healthy women with a mean age of 30 years were operated on for breast augmentation. Two surgeons performed all operations in a standardized way. Each patient received subglandularly a Siltex textured saline-filled prosthesis with a pore size of 30 to 70 microm in one breast, and a smooth saline-filled prosthesis in the other. The hardness of the breasts was evaluated after 0.5, 1, and 7.5 years using Baker grading and applanation tonometry. Eighteen patients completed 1-year and 7.5-year follow-up. Two breasts with smooth prostheses were contracted after 6 months (Baker III or IV). After 1 year, four patients with smooth prostheses and one with a textured prosthesis had capsular contracture (p = 0.34). Seven and one-half years after surgery, six patents with smooth and four with textured implants had contracture (p = 0.66). On two patients with smooth prostheses and one patient with a textured prosthesis, the capsule around the implant hardened between 6 and 12 months. Between 1 year and 7.5 years, three breasts with smooth and textured implants contracted and one with a textured implant softened.The patients reported on a Visual Analogue Scale (1 to 10) the impact of the augmentation on their quality of life to be 9 +/- 1. Four patients preferred the breast with the smooth prosthesis, three preferred the breast with the textured prosthesis, and the others found both breasts equal. This study showed no significant difference of contracture with smooth versus fine textured implants. The majority of the patients preferred the smooth implants. The patients reported that the breast augmentation had had an extremely high impact on their quality of life.     

Comparative experience with smooth and polyurethane breast implants using the Kaplan-Meier method of survival analysis.

Smooth-walled silicone implants have been widely used in breast surgery. Capsular contracture, causing undesirable firmness and spherical deformity, has been a common problem. Recent studies suggest that polyurethane-covered breast implants are associated with a lower incidence of capsular contracture. The statistical methodology employed in some of these studies, however, may be subject to criticism. Between July of 1984 and June of 1990 (72 months), 427 polyurethane breast implants were used in 279 patients and 439 smooth prostheses were used in 250 patients for a variety of aesthetic and reconstructive procedures. The occurrence of capsular contracture was carefully monitored and then analyzed using the Kaplan-Meier method of survival analysis. This method is particularly well suited to analysis of these types of clinical data because it allows for the fact that contractures occur at varying intervals after surgery and that follow-up of patients is incomplete. The probability of capsular contracture with smooth-walled prostheses was found to be significantly greater than with polyurethane-covered implants in each group of patients studied (p less than 0.05). Other complications occurred at a similar rate regardless of prosthesis type. This study supports the belief that polyurethane breast implants have a lower contracture rate; furthermore, it introduces the Kaplan-Meier method for analyzing the outcome of alternative plastic surgical therapies.     

The coincidence of TRAM flaps and prostheses in the setting of breast reconstruction

It is well known that transverse rectus abdominis myocutaneous (TRAM) flaps can be used to replace unsatisfactory prosthetic breast reconstructions; however, little has been written about the scope of breast implant use in TRAM flap patients. In this study, to ascertain the range of such therapeutic options, their frequency, and their clinical outcomes, the authors retrospectively reviewed the senior author's breast reconstruction experience from 1989 to 2000 with patients in whom both a TRAM flap and an implant were used for breast reconstruction. The authors examined the surgical indications, body habitus, bra size, chest wall irradiation history, flap type, implant type, complications, and outcomes for those patients with TRAM flap and breast implant combinations.Thirty-two women who had 50 (various) combinations of a TRAM flap and a breast implant were identified. There were more clinical scenarios than patients because many of the women had multiple scenarios. The 50 combination scenarios were then divided into six groups. Group I consisted of 14 patients who had elective prostheses placed beneath simultaneous TRAM flaps; group II consisted of 10 patients who had TRAM flaps with contralateral prosthetic reconstruction (in which two implants were received before the TRAM flaps, five implants were received simultaneously with the TRAM flaps, and three implants were received after the TRAM flaps); group III consisted of eight patients who had contralateral augmentation in addition to their TRAM flaps; group IV consisted of 11 patients who had TRAM flaps that were used to cover or replace previous prosthetic reconstructions; group V consisted of four patients in whom prostheses were used to augment or improve previous TRAM flap reconstructions; and group VI consisted of three patients who required prostheses to either reconstruct or salvage total or near-total TRAM flap failures. A broad range of implant types was used, although anatomic saline implants predominated. Forty-one percent of the patients in the review had undergone irradiation during the course of their treatment for breast cancer. Eight of the 32 patients experienced a total of twelve complications, four of which were related to the implants and eight of which involved the TRAM flaps and abdominal donor sites.Although complex, the wide variety of potential TRAM flap/breast implant combinations can be useful for patients with challenging reconstructive scenarios, particularly those that involve radiation therapy. In the group of patients reviewed by the authors, TRAM flaps were most often used in successful partnership either on the same side as or opposite to an implant reconstruction. A TRAM flap was used to salvage or replace an unsatisfactory implant reconstruction in less than a third of the patients. From a risk point of view, implants used opposite a TRAM flap reconstruction had a lower incidence of complication than did implants used beneath TRAM flaps.     

Capsular contracture in silicone gel and saline-filled breast implants after reconstruction

Comparisons between results with randomly allotted silicone-gel and saline-filled prostheses in breast reconstruction after mastectomy led to the following conclusions. Neither prosthesis type is ideal. Leakage from saline-filled implants occurred in 2 of the 37 implants, with resultant deflation. Silicone prostheses had a significantly higher rate of capsular contracture [surgeon's evaluation: 54 percent capsular contracture for silicone-gel compared with 20 percent for saline-filled prostheses (p = 0.006); patients' evaluation for the same figures: 54 percent compared with 29 percent (p = 0.03)]. Other authors have shown the presence of silicone in the tissue around silicone-gel-filled silicone implants, but less or none around saline-filled silicone implants. Since the only difference between the two groups was the randomly allotted implants, we assume that the free silicone around silicone-gel-filled prostheses is the major cause of capsular contracture. Since the saline-filled implants showed a 20 percent capsular contracture rate, there could be other causes of capsular contracture in this study. For prevention of contracture, improved implant encapsulation and use of a less reactive filling substance seem to offer possibilities. Surgical technique should aim to preserve the integrity of the prosthesis.     

Primary rotational stability of cylindrical and conical revision hip stems as a function of femoral bone defects: an in vitro comparison

Bone stock losses in cementless femoral stem revisions compromise a stable fixation. The surgeon has to rely on his wealth of experience in deciding which stem shape to use. The aim of our study was to compare the primary rotational stability of cylindrical and conical revision hip stems subjected to femoral defects. Four current prostheses (two cylindrical, two conical) were implanted into four synthetic femora. Micro-motion was measured under torque application and femoral neck osteotomy and segmental AAOS Type I and III defects were simulated. The relative movements of all prostheses were significantly influenced by the extent of bone loss (p<0.01). Major differences were seen in fixation behavior (p<0.01). The main fixation area of conical stems is within the distal femoral isthmus, whereas cylindrical implants are dependent on proximal bone stock. In our study, cylindrical stems are advantageous for minor defects because they provide a proximal fixation. In cases of extensive substance loss, the conical implants showed lesser relative movements. These findings should be taken into account for clinical decisions.     

Finite element analysis of implant-supported prosthesis with pontic and cantilever in the posterior maxilla

The aim of this study was to evaluate the influence of pontic and cantilever designs (mesial and distal) on 3-unit implant-retained prosthesis at maxillary posterior region verifying stress and strain distributions on bone tissue (cortical and trabecular bones) and stress distribution in abutments, implants and fixation screws, under axial and oblique loadings, by 3D finite element analysis. Each model was composed of a bone block presenting right first premolar to the first molar, with three or two external hexagon implants (4.0 × 10 mm), supporting a 3-unit splinted dental fixed dental prosthesis with the variations: M1 – three implants supporting splinted crowns; M2 – two implants supporting prosthesis with central pontic; M3 – two implants supporting prosthesis with mesial cantilever; M4 – two implants supporting prosthesis with distal cantilever. The applied forces were 400 N axial and 200 N oblique. The von Mises criteria was used to evaluate abutments, implants and fixation screws and maximum principal stress and microstrain criteria were used to evaluate the bone tissue. The decrease of the number of implants caused an unfavorable biomechanical behavior for all structures (M2, M3, M4). For two implant-supported prostheses, the use of the central pontic (M2) showed stress and strain distributions more favorable in the analyzed structures. The use of cantilever showed unfavorable biomechanical behavior (M3 and M4), mainly for distal cantilever (M4). The use of three implants presented lower values of stress and strain on the analyzed structures. Among two implant-supported prostheses, prostheses with cantilever showed unfavorable biomechanical behavior in the analyzed structures, especially for distal cantilever.     

Rehabilitation with ear prosthesis linked to osseointegrated implants

doi: 10.1111/j.1741‐2358.2011.00612.x Rehabilitation with ear prosthesis linked to osseointegrated implants Background: The absence of an ear, which can be the result of a congenital malformation, surgical tumour resection or traumatic injury, is a significant aesthetic problem. Attachment of ear prostheses with adhesives can cause local irritation for the wearer and affect the colour of the prostheses. Use of implants in craniofacial reconstruction can improve the retention and stability of prostheses giving to patient greater comfort and security relative to adhesive attachment. Objective: The aim of this report was to present a clinical case of a mutilated patient who was rehabilitated by means of installing an ear prosthesis fixed through osseointegrated implants. Materials and methods: The patient had two implants installed in the mastoid region that were linked by a bar, and a clip‐type system was used. The ear prosthesis was constructed from medical‐use silicone, pigmented to match the patient’s skin colour and linked to the retention system. Conclusion: The patient’s rehabilitation was satisfactory from both a functional and an aesthetic point of view, making it possible for the patient to return to a normal social life and regain lost self‐esteem.     

Discriminating the loosening behaviour of cemented hip prostheses using measurements of migration and inducible displacement.

In vitro pre-clinical tests of hip prostheses have not yet been developed to the extent that inferior prostheses can be 'screened-out' prior to animal or clinical trials. This paper reports the experimental part of a project to develop a pre-clinical testing platform for cemented femoral hip implants. It is based on the clinical observation (K?rrholm et al. JBJS, 76B (1994) 912-916) that higher subsidence (distal migration) correlates with early revision of hip prostheses. A protocol to measure the relative movement between implant and bone was designed to test whether or not such a measurement, if made in a laboratory, could discriminate between hip prostheses. The protocol was applied to the Lubinus SPII prosthesis (W. Link, Germany) and a Müller Curved Stem (JRI Ltd., UK)-these prostheses were chosen because they are known to have different loosening rates in vivo. Five prostheses of each design were tested. The migration, the rate-of-migration, and the inducible displacement of each prosthesis was recorded over two million cycles of loading.For each implant, rapid initial migration was found, followed by a period of steady-state migration. In the majority of cases, the prostheses migrated medially, distally and posteriorly. On average, the Lubinus migrated less than the Müller in all directions. The average Lubinus migration was less than half that of the Müller, and this difference was significant at a level of p=0.05. Inducible displacement was greater for the Müller compared to the Lubinus. Furthermore, the inducible displacement decreased over time for the majority of Lubinus prostheses whereas it increased over time for the majority of the Müller prostheses leading to the conclusion that a rapid pre-clinical test based on measurement of inducible displacement may be possible.     

Histologic changes and silicone concentrations in human breast tissue surrounding silicone breast prostheses

Using a previously developed method for quantitative measurements of silicone concentrations in breast tissue, material from 86 biopsies from 67 breasts in 55 patients who had silicone implants was examined. In the 49 breast with unruptured prostheses, there was a positive relation between the concentrations and inflammatory reactions, the only exception being the amount of plasma cells, which showed a negative relation. It is concluded that silicone prostheses provoke an inflammatory response not only because they act as foreign bodies, but also because of silicone seepage through intact membranes.