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PubMed1986

[Computer-assisted design and production of a femoral hip prosthesis].

The authors believe that a better design of prosthetic femoral stem might reduce the incidence of loosening. They have developed a method to make a prosthesis precisely adapted to a patient. Two X-Rays, one antero-posterior and one lateral view are taken. Several bony points are precisely determined. The magnification of the X-Rays is calculated, using a metallic circular collar placed around the thigh. A computer analyses the X-Rays, bony points are numerated and the prostheses have a length, thickness and shape adapted to the patient's hip. A study of the pressures transmitted by the prostheses to the bone was made using geometrical models. Compared to conventional prostheses, a prosthesis made as an exact fit to the hip of the patient reduces the pressure applied on femoral cortex by two thirds. A prosthesis with a collar also allows reduction of pressure on the cortex by a degree of three to one. The personalized prosthesis obtained by the use of a computer appears to be a stage in progress towards a better fitting and more reliable prosthesis. Twenty five patients have been operated on with good short-term results.

Computers↗

PubMed1986

Uncemented two-component femoral prosthesis for the hip joint. A 50-month follow-up study.

The Monk Duopleet femoral interlocking uncemented two-component endoprosthesis consists of a polyethylene cup covered by a metal cap and an Austin-Moore type stem. Seventy-two patients (average age, 71 years) were treated by this arthroplasty: 27 for subcapital femoral neck fracture, 36 for osteoarthritis, and nine as an exchange operation. Three patients died following operation. After a mean follow-up time of 50 months, 47 patients were reexamined clinically and radiographically. Because of loosening, four patients had the prosthesis removed. Twenty-six patients were classified as excellent, 12 as good, six as fair, and three as poor. There were no cases of acetabular intrusion. The Monk Duopleet prosthesis may solve the problem of the loosening that had been associated with femoral component alone. The long-term results are promising and appear to be better than the results of the standard Moore prosthesis. The Monk Duopleet prosthesis is an alternative to other two-component endoprostheses for the treatment of subcapital hip fractures and in the group of patients suffering from osteoarthritis, where an arthroplasty with a cemented prosthesis may be considered hazardous because of age or general disease.

Adult↗

PubMed1994

[Infected total knee prosthesis. Guidance for therapeutic choice].

PURPOSE OF THE STUDY: The aim of the study is to assess the functional results and septic evolution in the treatment of infected total knee arthroplasties. MATERIAL AND METHODS: 22 patients were reviewed; 8 were initially treated in our institution and 14 transferred from other hospitals. Articular debridement alone leaving the prosthesis in situ was initiated in 3 of our 8 patients as well as in 6 of the transferred cases. In both groups, this procedure appeared to be a failure. Prosthetic-reimplantation procedure was elected in 10 patients either as a one-stage (5 cases) or a two-stage surgery (5 cases). This has been successfully rated in 7 cases. Femoro-tibial arthrodesis was performed in 15 patients, three of them being a failure of the prosthetic reimplantation. Follow-up ranges from 16 months to 9 years with well documented records. RESULTS: As stated earlier, articular debridement alone has not proven to be a helpful procedure since it did not eradicate the septic complication in any case. Prosthetic reimplantation has been a successful treatment in 7 of the 10 attempted cases. The one-stage procedure is providing the best functional result. Recurrent infection occurred in 3 cases: there were patients with poor host defense (diabetes, arteritis, old age, ...) with resistant bacteria complicating a hinge-knee prosthesis. Femoro-tibial arthrodesis was achieved in 10 of the 15 patients and necessitated all together 23 surgical operations. The highest union rate was observed in cases where sterile conditions were achieved, fixation being performed with an intramedullary nail. Failure of arthrodesis confines the patients in such an uncomfortable situation that 2 of them has asked for an amputation. DISCUSSION AND CONCLUSION: Early surgical debridement may occasionally salve a prosthesis when it is performed shortly after the onset of infection, in an unloosened unconstrained prosthesis infected by a low-virulence organism. In our study, no patient but one met those criteria. For those cases nevertheless, our procedure of choice is now the one-stage reimplantation who seems to be more effective for eradicating the infection and gives rise to a better clinical result. The two-stage reimplantation is the current procedure for handling an infected knee prosthesis. Some patients are still excluded from this procedure because of their poor health condition, bone loss, inadequate viability of skin and extensor mechanism or an uncontrolled sepsis. For such a case, arthrodesis remains the most reliable method of management, especially when it can be stabilized with an intramedullary fixation, which implies to perform a two-stage arthrodesis.

Adult↗

PubMed1994

[An obturator prosthesis in a patient with perfect dentition. Functional, esthetic approach].

A prosthesis was implanted immediately after operation for a velo-palatal tissue defect in an active young female patient in order to avoid function, psychological and social complications involved with this mutilation. The three classical steps of the process were performed: immediate implantation of the prosthesis, temporary prosthesis, definitive prosthesis. Anchoring to the teeth maintained the prosthesis in position. A functional print is always needed to obtain perfect closure. A metallic bridge links the retention part and the obstructive part. The device is effective, discrete, functional and well-tolerated by the patient.

Adult↗

PubMed1994

Photoelastic simulation of a cementless and of a hydroxyapatite coated total hip prosthesis.

Remodelling of bone, regularly observed after the implantation of a hydroxyapatite coated Furlong hip prosthesis, stimulated the authors to analyse the stress distribution and relative magnitude in photoelastic models, of 1. the upper half of an intact femur; 2. of a femur equipped with a prosthesis free of glue to simulate the implantation of a cementless non coated prosthesis; and 3. of a femur in which a prosthesis was glued to simulate the implantation of a hydroxyapatite coated prosthesis. The results match precisely the remodelling thus observed in the X-rays.

Biomechanical Phenomena↗

PubMed1993

Long-term results with the uncemented thrust plate prosthesis (TPP).

The long-term clinical results of a novel concept for total joint replacement called the Thrust Plate Prosthesis (TPP) are presented. Only a restricted number of patients were provided with this new prosthesis (115 at the Orthopedic Department, Canton Hospital, Chur, and 47 at the Department of Orthopedic Surgery, University of Zurich). All patients have undergone clinical and radiological follow-up covering a period from 1980 to 1991. The basic feature of the Thrust Plate Prosthesis is the direct load transfer to the medial cortical bone of the femoral neck, and this has been unchanged since 1978. Titanium alloy has been used since 1986. The good clinical and radiological results are confirmed by a histological examination of an 8-year-old implant: In the crucial area of load transfer newly formed bone can be seen in direct contact with the thrust plate without fibrous tissue in between. The clinical results and histological findings have confirmed the validity of the biomechanical principle of the TPP. The TPP is therefore to be considered a true alternative to the conventional hip prosthesis. In contrast to the conventional intramedullary anchored stem prosthesis the TPP requires the removal of a minimum amount of bone stock, which is certainly important in young patients.

Adult↗

PubMedDate not supplied

[Infection involving arterial prosthesis: clinical picture, etiology, and predisposing factors].

Thirty patients were operated for arterial reconstruction with synthetic grafts. They presented one of the following complications: 1) prosthesis exposed by a cutaneous fistula; 2) prosthesis in communication with a hollow viscus; 3) prosthesis involved by pus; 4) positive culture of a fragment of the prosthesis or of the surrounding secretion. The clinical manifestations were cutaneous fistula in 21 patients (70%), external bleeding in 14 (47%), exposition of the prosthesis in five (17%), anastomotic aneurysm in five (17%), and enteric fistula in four (13%). The infection became evident during the first postoperative year in half of the patients. The most important agents of infection were staphyilococci and Gram negative bacteria.

Adult↗

PubMed1995

[Bousquet's device in the treatment of recurrent dislocation of a total hip prosthesis. Apropos of 13 cases].

PURPOSE OF THE STUDY: Dislocation following total hip arthroplasty (THA) continues to be a problem. An innovative treatment is described with the intermediate Bousquet's prosthesis. This study reported 13 cases and demonstrates its high reliability despite the origins of the dislocation. Recurrent dislocation following initial dislocation, occurs in between 25 to 60 per cent of the cases reported in the literature. The main cause is a malpositioned prosthetic component and especially a retroverted acetabulum. The other reasons for dislocation were: trochanteric non-union, bone or cement impingement, previous surgery, age and neurologic disorder. In every case the instability of the hip may be caused or increased by muscular insufficiency. Various methods are described to control recurrent dislocation: repositioning the component, posterior acetabular wall component, trochanteric advancement, retentive acetabular component, bracing. When the cause is clear and isolated, the rate of success may be 70-80 per cent. This study examines the results of a revision procedure with the intermediate Bousquet's prosthesis. MATERIAL AND METHODS: 13 recurrent dislocations were treated with the intermediate Bousquet's prosthesis. There were 10 women and 3 men with an average age at operation of 73 years. The main cause in 7 cases was an abductor insufficiency including 4 trochanteric non unions. The other causes were 6 component malpositions, 7 previous surgery, 1 impingement. The average delay between the first dislocation and revision was one year. The Bousquet's acetabular component is an steel cup covered with alumina, impacted without cement. The polyethylene component is free in the cup and retentive on the femoral head. The femoral positioning was not modified. RESULTS: The revision did not correct all of the causes of luxation, however we noted only one case of dislocation and no recurrent dislocations. DISCUSSION: At last follow-up, all recurrent dislocations were controlled. Nevertheless, there remained 7 abductor insufficiencies and 4 femoral malpositionings. In the literature the rate of success depends on the cause. The main difficulty is the treatment of joint laxity. Some authors propose trochanteric advancement, a larger head, a posterior wall acetabular component, retentive acetabular component. Success is not uniform. The Bousquet's acetabular component supports joint laxity and femoral malpositioning. This allows to keep the same original femoral component when the risk is too high for a cemented prosthesis or impossible for a non cemented prosthesis. CONCLUSION: This treatment of the recurrent dislocation is reliable with a short and simple operation.

Aged↗

PubMed1977

[Our experiences with total hip prosthesis model "St. George"].

The advantages of the total prosthesis of the hip in the treatment of some degenerative diseases and single traumatic impairments of the hip are described, and the main characteristics of the St. Georg model total prosthesis of the hip are discussed. The results obtained in 92 cases of total prosthesis of the hip have been satisfactory. Special attention has been paid to measures for the prevention of infections. Among the patients treated only one developed infection. The author points to the fact that it is possible to replace an infected prosthesis and achieve complete cure by using bone cement mixed with an antibiotic. The functional results obtained are good: pain is either completely relived, or significantly diminished on walking and movement. During the author's five-year experience signs of wear of the prosthesis have not been recorded in any case.

Aged↗

PubMed1996

[Dislocation-dissociation of a bipolar hip prosthesis].

The incidence of hip prosthesis dislocation ranges from 0.4% to 15% depending on the series (1, 6). In classical dislocations of hip prosthesis, the prosthetic femoral head escapes from the natural acetabular cavity or prosthetic acetabulum in case of total hip arthroplasty. In the case presented here, a bipolar hip prosthesis dislocation occurred between the small head of the prosthesis and the polyethylene. A total hip prosthesis restored good function. Only a few cases of this type have been described in the literature. The different causes are discussed.

Hip Dislocation↗

PubMed1998

Immediate salvage procedure for infected penile prosthesis.

PURPOSE: The most devastating complication after the insertion of a penile prosthesis is the development of infection. The standard approach involves removing the entire device, treating intensively with antibiotics and attempting to reinsert a prosthesis at a later date, often with a suboptimal result. Based on the encouraging results of others, during the last 24 months we have used in 2 separate private urological practices a salvage procedure for treatment of infected inflatable penile prostheses. MATERIALS AND METHODS: The protocol used in 7 men with an infected inflatable penile prosthesis included removal of all device components, a 7-step vigorous intraoperative irrigation with 4 different solutions, including vancomycin, immediate reimplantation of a new inflatable penile prosthesis and postoperative outpatient antibiotics with oral ciprofloxacin or intravenous vancomycin or cefazolin. RESULTS: Of the 7 men 6 have experienced excellent results with no infection, minimal morbidity and preservation of penile length. The only failure occurred in a poorly controlled diabetic who required multiple revisions and may have had latent infection for months before it became apparent. CONCLUSIONS: We believe that an immediate salvage procedure for an infected inflatable penile prosthesis is an effective treatment for this difficult complication.

Adult↗

PubMed1998

[A knit vascular prosthesis of RaK collagen--a clinical evaluation study].

Vascular collagen prosthesis of RaK type (collagen-impregnated knitted prosthesis) made by Výzkumný ústav pletarský (Research Institute of Hosiery) in Brno was introduced into clinical practice in 1990. In comparison with previous type, the collagen-impregnated prosthesis has had a number of advantages and thus it gets into the interests of vascular surgeons. The report presented has given the results of clinical evaluating study carried out at the IInd Clinic of Surgery, Faculty of Medicine, Masaryk University, Brno according to the methods of EN 540 European Norm Proposal for clinical studies. The results obtained from evaluating a set of 107 patients created for this study (besides others, long-term patency of 90.7%, or 0.9% incidence of infection of the vascular prosthesis of Szilagyi III type) have shown that nowadays we have at disposal a very good, reliable and economically acceptable vascular prosthesis of our provenience.

Blood Vessel Prosthesis↗

PubMed1998

Buckling of cylinders may cause prolonged penile pain after prosthesis implantation: a case control study using magnetic resonance imaging of the penis.

PURPOSE: We identify risk factors associated with chronic postoperative penile pain after inflatable prosthesis insertion. MATERIALS AND METHODS: We performed a case control study to determine the incidence of prolonged penile pain in 65 men who underwent prosthesis insertion. The association of various potential risk factors, including diabetes mellitus, incision site, prosthesis type, patient age and history of pelvic surgery, was assessed. In addition, the penis was examined for physical findings, and penile magnetic resonance imaging (MRI) was done as an in situ evaluation of the anatomical position and functional status of the inflatable prosthesis. RESULTS: A total of 14 patients (21.5%) with prolonged pain were compared to the remaining 51 with no pain. All parameters evaluated were similar in both groups except for MRI findings. Of the 14 patients with pain 12 (85.7%) had buckling of the cylinders in the flaccid state compared to only 1 of the 51 controls (1.9%). Statistical analysis showed a highly significant association between buckling and penile pain (odds ratio 300, p <0.0001). Surgical correction of buckling resolved pain in 5 patients. CONCLUSIONS: Prolonged postoperative penile pain after prosthesis insertion is strongly associated with cylinder buckling. This buckling may be the consequence of an excessively long cylinder or an appropriate size cylinder that fails to reach the crural end. The method of accurately diagnosing these alterations is MRI of the penis.

Case-Control Studies↗

PubMed1998

The VoiceMaster voice prosthesis for the laryngectomized patient.

Since the introduction and performance of total laryngectomy, voice restoration has become an important issue. Voice prostheses are widely used for this purpose. Based on experience with previous and current prostheses, the important characteristics for any voice prosthesis can be defined. These characteristics are: indwelling fixation, low resistance to airflow, less bothersome and easier insertion into the tracheoesophageal (TE) fistula. Also, predictable long device life span (resistance to Candida deterioration) and easy removal of the prosthesis to allow inspection or cleaning and consequent re-insertion are desirable. The VoiceMaster voice prosthesis was developed with these characteristics in mind. The VoiceMaster prosthesis is described in this paper. The first results from the preliminary study in which the currently available VoiceMaster was tested are very encouraging.

Candidiasis↗

PubMed1996

[Clinical experience with a new antimicrobially coated InterGard-IgK/AM vascular prosthesis in surgical treatment of deep wound infection with involvement of the synthetic bypass: report of 2 cases].

We report 2 cases of infected vascular prosthesis, where the infected alloplastic material was removed and the revascularisation of the lower extremity was done by implantation of the new antimicrobial surface-coated InterGard prosthesis in the area of the former infected graft. An extra-anatomical bypass was not promising in these cases. Clinical, bacteriological and granulocyte-scintigraphic examinations have provided no evidence for persisting infection 12 and 11 months after implantation of this prosthesis. We are aware that the postoperative observation periods are too short to allow definitive assessment. Nevertheless we still consider that this prosthesis means a new and promising option in the treatment of infected vascular graft.

Angiography↗

PubMed1999

The long-term indwelling tracheoesophageal prosthesis for alaryngeal voice rehabilitation.

OBJECTIVE: To analyze the initial experience at Oregon Health Sciences University, Portland, with the use of long-term indwelling tracheoesophageal voice prostheses. DESIGN: Retrospective case series. SETTING: Tertiary referral academic medical center. PATIENTS: Thirty patients undergoing speech rehabilitation after laryngectomy during a period of 18 months. INTERVENTION: Insertion of a long-term indwelling tracheoesophageal voice prosthesis. MAIN OUTCOME MEASURES: Duration of use, complications. RESULTS: The mean duration of placement for a single prosthesis was 4.9 months (148 days), with a range of 14 to 330 days. Sixteen of the 30 patients encountered problems with leakage because of fungal colonization, the majority of which (15 of 16 cases) were solved with either oral or topical application of nystatin. Size matching in terms of prosthesis length and tract length was critical, and problems of this nature were encountered in 11 of 30 patients. The incorporation of a second system of prostheses that offered an increased number of size options solved these problems in all of these patients. Ultimately, 27 of 30 patients were able to successfully wear these prostheses. CONCLUSIONS: The indwelling tracheoesophageal voice prosthesis offers patients all the advantages of tracheoesophageal speech rehabilitation after laryngectomy without the inconvenience of frequent prosthesis changes. With careful attention to the details of fitting and care, it can be worn by the majority of patients successfully.

Humans↗

PubMed1994

Isolation and characterization of metallic wear debris from a dynamic intervertebral disc prosthesis.

A dynamic intervertebral disc prosthesis (DIDP) has been developed. It consists of a CoCrMo body and uses Ti6Al4V springs to replicate the mechanical function of the lumbar joint. Wear studies have been performed previously on the DIDP using two specialized simulators to test the wear properties of the moving parts of the disc prosthesis. A pin-in-slot simulator generates wear that would occur in the hinge-pin assembly of the prosthesis. A spring-in-pocket simulator approximates the conditions under which the springs would wear against the body of the prosthesis. The spring-pocket interface is responsible for the production of approximately 90% of the total wear occurring in the prosthesis, and is therefore the main focus of this study. Bovine serum with a preservative has been used as a lubricant in both simulators. The spring-in-pocket simulator compares the effects of two different manufacturing techniques of CoCrMo (HIPing and forging) on their wear characteristics against Ti6Al4V springs. Debris from the spring-in-pocket simulator has been isolated from the serum lubricant and characterized using scanning electron microscopy techniques. The morphology of the Ti6Al4V fragments is rough and irregularly shaped. The size of these fragments ranges from < 1 microns to > 30 microns. The forged CoCrMo alloy debris has an irregular polyhedral shape, with sizes in the same range as the spring fragments. The morphology of the HIPed CoCrMo debris is spherical with a size range < 5 microns to > 30 microns. Length and width measurements of micron-size particles were made with the particle measurements feature of the scanning electron microscope. Micron-size particles were found in all stations. This article provides a unique way to isolate and analyze debris from serum lubricants used in simulators.

Alloys↗

PubMed1977

Phonocardiographic and echocardiographic features of Lillehei-Kaster mitral prosthesis.

Fifteen patients were studied with phonocardiography (phono) and echocardiography (echo) three to 13 months after mitral valve replacement with Lillehei-Kaster mitral valve prostheses. Echo measurements in all patients included prosthesis excursion (DE), opening velocity (OV), closing velocity (CV), and Q-to-mitral prosthesis closure (Q-MPC). In five patients, further, echo measurements included isometric contraction period (ICP), left ventricular ejection time (LVET), and time to completion of aortic valve opening (TCAO). Phono measurements in all patients included pre-ejection period (PEP), LVET, and PEP/LVET. Further phono measurements in the same five patients in whom further echo measurements were performed included Q to first heart sound (Q-S1), ICP, and isometric relaxation period (IRP). Phono and echo measurements were done sequentially. The echo results showed widespread values for DE, OV and CV with no correlation between clinical state, size of prosthesis, or postoperation duration. There was a positive correlation between CV and OV, r + 0.65. Q-MPC by echo averaged 72 msec, which is longer than reported values for Q-to-mitral valve closure in normal people. Similarly, ICP by echo was shorter than ICP by phono in every patient. Of the phono measurements IRP was shortest (45 msec) in one patient in congestive heart failure with a possible prosthesis malfunction. We conclude that echo- and phonocardiography are useful tools in evaluating mitral prosthesis function, but because normal values are widespread, individual measurements may be useful for followup in the same individual. Precise measurement of subdivisions of systolic intervals are now possible with these techniques.

Adult↗