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At least 325 records · Page 18Linked to original sources
PubMed2005

Effect of a buccal bioadhesive nystatin tablet on the lifetime of a Provox silicone tracheoesophageal voice prosthesis.

CONCLUSION: Daily application of a buccal bioadhesive slow-release nystatin tablet (100,000 IU per tablet) significantly increased the voice prosthesis lifetime in laryngectomized patients compared to conventional local cleaning of the prosthesis with an antimicrobial agent on a brush. OBJECTIVE: To investigate the effect of a buccal bioadhesive nystatin tablet on the lifetime of a Provox tracheoesophageal voice prosthesis in post-laryngectomy patients. MATERIAL AND METHODS: A buccal bioadhesive tablet, based on a spray-dried Amioca/Carbopol 974P mixture containing 10% (w/w) Carbopol 974P, was loaded with 100,000 IU of nystatin. Patients were included in the study when replacement of their voice prosthesis was required and were divided into three groups. Conventional daily local cleaning of the voice prosthesis by means of an oral nystatin suspension on a brush (Group 1; n = 7) was compared with application of one nystatin buccal bioadhesive tablet per day, after breakfast, on the gingiva above the upper canine (Group 2; n = 7). The control group (n = 5) used no antimicrobial agents. The lifetime of the prosthesis was followed and expressed in days. RESULTS: The lifetime of the voice prosthesis was significantly increased in Group 2 compared to Group 1 (p < 0.05; paired t-test), indicating that sustained release of nystatin in the oral cavity, by means of erosion of the tablet over a period of approximately = 8 h, is more effective at preventing microbial colonization of the prosthesis than local cleaning.

Acrylic Resins↗
PubMed1998

Management of impending penile prosthesis erosion with a polytetrafluoroethylene distal wind sock graft.

PURPOSE: Erosion of penile prostheses can be calamitous, often leaving patients unable to accommodate further implants. There is a paucity of literature describing impending erosion of penile prosthesis. We report on 5 patients with impending erosion of a penile prosthesis who underwent polytetrafluoroethylene distal wind sock graft placement. MATERIALS AND METHODS: From 1993 to 1997, 5 patients with a mean age of 49 years and impending penile prosthesis erosion underwent 6 revisions using a polytetrafluoroethylene distal wind sock graft. Two patients underwent simultaneous bilateral grafts while 1 patient underwent separate right and left grafts 3 years apart. Indications for reconstruction included distal migration of the prosthetic cylinders into the glans in 4 patients and impingement of the distal urethra in 2. Of the patients 3 were spinal cord injured, 1 had lumbar radiculopathy and 1 had a history of pelvic irradiation. Inflatable prostheses were implanted in 4 patients, while 1 received a malleable prosthesis. RESULTS: Patients underwent a mean of 1.5 penile prosthetic revisions (0 to 4) before diagnosis of impending erosion. An interval of 8 to 144 months (mean 66) elapsed from the most recent penile prosthesis insertion until distal wind sock graft placement. Mean operative time was 1 hour 51 minutes (1.3 to 2.5 hours). Mean hospital stay was 6.3 days (3 to 12). At a mean followup of 32 months (0.7 to 5.2 years) all patients had satisfactory and functional erections with no pain or evidence of impending erosion or penile prosthesis infection. CONCLUSIONS: Erosion of a penile prosthesis can have disastrous consequences. We describe a safe and effective technique for managing impending penile prosthesis erosion using a polytetrafluoroethylene distal wind sock graft.

Humans↗
PubMed2006

A mobile-bearing knee prosthesis can reduce strain at the proximal tibia.

Mobile and fixed-bearing knee prostheses are likely to generate distinct strain gradients in the proximal tibia. The resulting strain distribution in the proximal tibia governs bone remodeling and affects implant integration and stability. We determined the effects of fixed and mobile-bearing total knee prostheses on strain distribution at the proximal tibia. This mobile-bearing prosthesis was evaluated in cadaveric specimens under axial and torsional loading. Strain on the proximal tibial cortex was measured with rosette strain gages and an optical full-field strain acquisition system. Tibial torsion in response to combined axial and torsional loading was documented. There was no difference in cortex strain between the fixed and the mobile-bearing prostheses under 1.5 kN axial loading. Superimposing 10 degrees tibial internal rotation induced 22% less compressive strain in the mobile-bearing prosthesis compared with the fixed-bearing prosthesis. Under 10 degrees tibial external rotation, the mobile-bearing prosthesis induced 33% less compressive strain than the fixed-bearing prosthesis. Optically acquired strain fields showed peak compressive strain at the anteromedial aspect 30 mm below the joint line. The mobile-bearing prosthesis reduced torque in the proximal tibia during knee rotation by 68-73% compared with the fixed-bearing prosthesis. Our data suggest that the particular mobile-bearing prosthesis tested potentially reduces elevated strain levels in the proximal tibia.

Aged↗
PubMed2006

Results after revision stapedectomy with malleus grip prosthesis.

Revision stapedectomy with a malleus grip prosthesis is a technically challenging otologic procedure. The prosthesis is usually longer and extends deeper into the vestibule than a conventional stapes prosthesis, creating the potential to affect the vestibular sense organs. The prosthesis also bypasses the ossicular joints, which are thought to play a role in protecting the inner ear from large changes in static pressure within the middle ear. The prosthesis is in close proximity to the tympanic membrane, thus increasing the risk for its extrusion. We reviewed our experience with revision stapedectomy with the Schuknecht Teflon-wire malleus grip prosthesis in 36 ears with a mean follow-up of 23 months. The air-bone gap was closed to within 10 dB in 16 ears (44%) and to within 20 dB in 26 ears (72%). The incidence of postoperative sensorineural hearing loss was 8% (3 ears). There were no dead ears. Extrusion of the prosthesis occurred in 1 case (3%). Nearly 50% of patients reported various degrees of vertigo or disequilibrium during the first 3 weeks after surgery. These vestibular symptoms resolved by 6 weeks in all but 1 case. We did not find evidence of damage to the inner ear due to the length of the prosthesis or due to the potential for direct transmission of changes in static pressures within the middle ear to the labyrinth. Our results are similar to those published in the literature for malleus attachment stapedectomy and conventional revision incus stapedectomy.

Adult↗
PubMed2000

Survival of various implant-supported prosthesis designs following 36 months of clinical function.

BACKGROUND: The use of endosseous dental implants to replace natural teeth lost to trauma, dental caries, or periodontal disease has become a predictable form of prosthetic treatment since gaining popularity in the early 1980s. While numerous clinical studies have focused on the survival of implants, few address the survival of different prosthesis designs. METHODS: Beginning in 1991, 882 prostheses supported by more than 2,900 implants (687 patients) were placed by the Department of Veterans Affairs Dental Implant Clinical Research Group (DICRG). These prostheses were divided into five research strata based on arch location. The recommended design for each stratum was: bar-supported overdenture (maxillary completely edentulous); screw-retained hybrid denture (mandibular completely edentulous); screw-retained fixed partial denture (mandibular and maxillary posterior partially edentulous); and cemented single crown (maxillary anterior single tooth). Alternative overdenture designs were utilized in the edentulous arches when the recommended prosthesis could not be fabricated. Prosthesis success rates for the research strata were calculated for an observation time of up to 36 months following prosthesis placement. RESULTS: Success rates for the maxillary edentulous stratum ranged from 94.6% for the bar-retained overdenture supported by five to six fixtures to 81.8% for the cap-retained overdenture. The mandibular edentulous strata produced success rates of 98.1% for the fixed hybrid prosthesis to 91.7% for the cap-retained prosthesis. Success rates for maxillary and mandibular posterior fixed partial dentures were 94.3% and 92.6%, respectively, while the maxillary anterior single-tooth prosthesis yielded a success rate of 98.1% for the 36-month observation period. CONCLUSIONS: The recommended prosthesis designs investigated in this study proved to be reliable, with encouraging success rates for an observation period of 36 months following placement.

Alloys↗
PubMed2000

[Hand on composite prosthesis after resection of peri-acetabular sarcoma].

PURPOSE OF THE STUDY: To improve function after pelvic resection involving theacetabulum we have used an anatomic composite implant built with screws and cement. MATERIAL AND METHOD: Since 1990, 27 patients with peri-acetabular bone sarcoma have been treated by extensive resection followed by "hand on innominate prosthesis with constrained total hip prosthesis. The hand on innominate prosthesis was made of a titanium cup, a set of long titanium screws and 2 or 3 packs of gentamycin loaded ciment. RESULTS: Many postoperative complications were observed; deep infection (15 p. 100), hip prosthesis dislocation (33 p. 100) and local recurrence (17 p. 100). Nine patients (33 p. 100) had to be reoperated. Nevertheless at last follow up 24 patients still had their composite prosthesis. The mean functional result, rated according to a modified Enneking's staging system, was 83 p. 100 with unlimited walking without support, average hip flexion 100 degrees, length discrepancy less than 1 centimeters. DISCUSSION: These results were similar to those described in the literature for custom made innominate prosthesis and much better than those of alternative reconstructive procedures. Hand on composite prosthesis is cheaper, easier, more adaptable and enables better anchorage than custom-made prosthesis. Such a procedure can be used even after total iliac wing resection. CONCLUSIONS: The advantages of such procedure pleads for using it extensively after acetabular resection. But long term follow up is necessary to validate indications.

Acetabulum↗
PubMed1992

Valve prosthesis hemodynamics and the problem of high transprosthetic pressure gradients.

Recent studies suggest that all prosthetic valves are at least mildly stenotic and may cause relatively high pressure gradients despite normal prosthesis function; such gradients could be due to a mismatch between prosthesis effective orifice area and patient's body size. In order to address this problem more directly, we derived, using a physiologic pulse duplicator system, the theoretical relations between transprosthetic pressure gradients and prosthesis effective orifice areas indexed for body surface area, assuming a normal resting cardiac index of 3.0 l/min m-2 and 10-50% increases in stroke volume such as may occur during maximal upright exercise. These exponential relations show that a small decrease in indexed effective orifice area produces a large increase in pressure gradient, and that the indexed effective orifice area should ideally be not less than 0.9-1.0 cm2/m2 for aortic prostheses and 1.3-1.5 cm2/m2 for mitral prostheses in order to minimize postoperative gradients. Thus, high postoperative gradients do not necessarily indicate intrinsic prosthesis dysfunction but may also be due to patient prosthesis mismatch. Intrinsic prosthetic performance is best assessed by comparing in vivo calculated effective orifice areas to in vitro measurements for same type and size of prosthesis. Patient prosthesis mismatch can be avoided by calculating before operation the projected indexed effective orifice area of the prosthesis being implanted.

Aortic Valve↗
PubMed1991

[Valve replacement with Macchi prosthesis].

OBJECTIVE: to evaluate the performance of a new ball valve prosthesis. DESIGN: set up of two groups of patients who underwent mitral valve replacement with two different prosthesis: the Macchi prosthesis under evaluation and the well known Starr-Edwards model prosthesis. The chi-square test was used to compare the results. PATIENTS: Patients referred for valvular surgery. INTERVENTIONS: One group of 98 consecutive patients who underwent isolated mitral valve replacement with a Macchi prosthesis from January 1984 to June 30 1986 was compared to a matched group of 49 patients who received a Starr-Edwards prosthesis in the same period of time. Follow-up data were available from 99% patients in the Macchi group 96% in the Starr-Edwards group, with a mean follow-up time of 35.2 (2-57) and 42.9 (4-62) months, respectively. RESULTS: There was no statistical difference in the incidence per 100 patients--month of prosthetic complications--thromboembolism, hemorrhagic events, prosthetic endocarditis, reoperation and mechanical failure. CONCLUSIONS: In our experience and with the available follow-up data the Macchi prosthesis is a good cost effective option when there is indication for a ball valve prosthesis.

Adult↗
PubMed1990

[A complete intermediate temporomandibular joint prosthesis. Evaluation after 6 years].

Since 1983 we have inserted more than 100 temporomandibular joint prostheses. A review after 6 years allows the respective indications to be listed and the complications to be studied in 72 insertions involving 62 cases suitable for analysis. The prosthesis is a total intermediary prosthesis forming an unsealed cupula composed of 2 halves--a mandibular portion and a temporal portion. Insertion of the prosthesis requires preliminary facial nerve dissection then osteotomy of the mandibular condyle and its subsequent drilling to allow the screwing in of the prosthesis. The prosthesis was used in traumatology, in condylar and high sub-condylar fractures, in the event of failure of functional treatment, in malformation syndromes, in tumors and, finally, in degenerative pathology. 13 prostheses were removed. A study of the probable causes of complications shows a predominance of technical problems related to inaccurate positioning of the prosthesis, in that it was not placed in the axis of the condyle, or that inadequate bicortical support was present. In our opinion, these complications do not question the conception of the prosthesis but rather indicate that it is necessary to perfect the insertion technique while taking advantage of improvements in the prosthesis which are currently under study.

Ankylosis↗
PubMed1989

[A comment on optimal shaped prosthesis for tricuspid valve using an experimental model].

The prosthesis for mitral valve has been in use instead of the prosthesis for tricuspid valve, since the latter prosthesis has not at present been available. In view of the shape of tricuspid valve, which is essentially flat in form, it is not good for replacing with the prosthesis for mitral valve which has an almost circular shape because of the difficulties in suturing, and many criticisms on this substitution have been raised. In order to obtain more suitable prosthesis as exactly benefits TVR, we have developed at first an instrument indicating the change of cardiac function occurring in the course of fixing the annulus of tricuspid valve that would undergo the difference in shape from circular to flat, using experimental models throughout, which has eventually led to the exploration of the possible exact shape of a prosthesis of the annulus for tricuspid valve. Our series of experiments proved as conclusion that the annulus of tricuspid valve is more advantageous when fixed with an ellipse of a flattened rate 1.6 compared with any circular ones tested. In view of the left ventricular stroke work, it is apparent that a prosthesis for mitral valve which is circular in shape should not be applied. We emphasize that a prosthesis for tricuspid valve which is ellipse in shape with desired flattened rate of 1.6 should be developed for our future applications.

Animals↗
PubMed1988

Design considerations for a small bore vascular prosthesis.

No synthetic prosthesis has yet been found which can satisfactorily be used as a substitute for saphenous veins in vascular surgery. One explanation for the lack of success is that their properties and behaviour do not mimic those of the arteries they replace. The essential features for a successful vascular prosthesis, over and above biocompatibility, are a low friction non-thrombogenic flow surface, mechanical (elastic) behaviour that matches natural artery and dimensions that approximate the host vessels. This will allow a high velocity of flow with low impedance. A prosthesis with this specification would avoid the problems of flow disturbances and reflection at the anastomoses, pulse wave damping and large pressure gradients, all of which reduce pulsatile energy. We have designed a vascular prosthesis based upon the above criteria. It has an internal diameter of 4 mm and a wall thickness of 1 mm. Its geometry makes it kink resistant and a good match for tibial and coronary arteries. The prosthesis is made from polyurethane and its mechanical properties, which approximate to those of peripheral arteries, are achieved via a mechanism of internal wall compression rather than external circumferential expansion. To assess the in-vivo potential of this prosthesis, 21 grafts were implanted in 11 sheep, replacing a section of carotid artery with a 6 cm long prosthesis. All 21 grafts were patent after 3 months. One graft was removed for histological examination. 16 of the remaining 20 grafts were patent after 7 months. Problems associated with thrombosis were not encountered and we conclude that this prosthesis shows good potential as a small bore vascular substitute.

Animals↗
PubMed1996

Preoperative echocardiographic prediction of small prosthesis size for aortic valve replacement.

BACKGROUND AND AIMS OF THE STUDY: Prosthesis size is known to have an effect on long term outcome after heart valve replacement. We evaluated 115 patients subjected to aortic valve replacement to assess the ability by preoperative echocardiography to identify patients having small aortic roots and thereby likely to receive a small prosthesis (size 19 or 21), previously shown to be associated with a worse prognosis. METHODS: From an initial part of the study (Group A), comprising 67 patients, we evaluated the influence of image quality on the accuracy for prediction of patients receiving a small prosthesis. In a second series of 48 patients (Group B), we tested the predictive value of various limits of aortic annulus diameter to define patients at risk of receiving a small prosthesis. RESULTS: The measurement of aortic annulus diameter in Group A gave a reasonable correlation to subsequent prosthetic dimension (r = 0.73, n = 59). However, there was a considerable variation of echocardiographic aortic annulus diameter among patients receiving prostheses of the same size. In Group B, an aortic annulus diameter of < or = 22 mm correctly identified 10 of 13 patients receiving a small prosthesis (sensitivity 77%). Twenty-two of 25 patients (88%) with an aortic annulus diameter > 22 mm received a large prosthesis. CONCLUSIONS: We conclude that the echocardiographic measurement of the aortic annulus diameter is a fairly sensitive method to identify patients receiving a small prosthesis. However, the predictive accuracy is dependent upon training as well as image quality. Furthermore, the value of planning in advance the type of prosthesis, annuloplasty or homograft for aortic valve replacement remains to be shown.

Aged↗
PubMed1996

[Penile prosthesis. Indications, classification, technic, complications, and safety].

OBJECTIVES: To review the indications of penile prosthesis in the treatment of erectile dysfunction and describe a new classification based on the design and material of the prosthesis. METHODS: Penile prosthesis are classified. The advantages and disadvantages of the different prosthesis types are given. The surgical technique is described, as well as the pre-, intra- and postoperative complications observed in 300 procedures involving penile prosthesis performed over a 10-year period. RESULTS: 6 of the 300 prosthesis required removal (4 of these 6 prosthesis were reimplanted); 17 prosthesis were changed due to implant failure. CONCLUSIONS: Penile prostheses are the best solution currently available for erectile dysfunction not amenable to any other type of treatment and carry minimal complications if the technique is performed correctly.

Humans↗
PubMed2005

Segmental cement extraction system (SEG-CES) and the Ilizarov method in limb salvage procedure after total knee cemented prosthesis removal in a former osteosarcoma patient.

Survival of osteosarcoma has greatly improved in the past few decades. Knee prosthesis is a well-recognized limb salvage procedure for osteosarcoma of the distal end of the femur. One drawback is that prostheses have a limited life and prosthetic failure with the inherent high rate of reoperations remains a serious long-term problem for former osteosarcoma patients. The segmental cement extraction system (SEG-CES) is a technique to remove cement in arthroplasty revision, based on a cement-bone interface with a lower strength compared to the old cement-new cement interface. We report the case of a 32-year-old former osteosarcoma patient in whom the SEG-CES was applied to remove a long-stemmed total knee cemented prosthesis. The prosthesis was placed 17 years before for a recurrent telangiectatic osteosarcoma of the left femur. Thirteen years after the prosthesis implantation, the patient complained of knee instability, pain, and complete failure of the extensor apparatus. The extraction of the prosthesis was performed using cylindrical batters of diameter corresponding to the diameter of the axle, two hammer extractors clamping the prosthesis components between two jaws. Extraction of the periprosthetic cement in the femoral and tibial components was done using the SEG-CES technique. The successful prosthesis removal performed in this patient allowed us to perform an external fixation with bone lengthening and reconstruction by the Ilizarov method.

Adult↗
PubMed2002

Downsizing of voice prosthesis diameter in patients with laryngectomy: an in vitro study.

In patients with laryngectomy, voice prostheses inserted into a tracheoesophageal fistula (TEF) are widely used for vocal rehabilitation. Gradual dilation of the TEF may cause bothersome leakage around voice prostheses. Prosthesis-related weight and mechanical trauma possibly exacerbate TEF dilation. If prosthesis size were to be decreased, with a concomitant decrease in prosthesis weight and diameter, dilation of the TEF would probably lessen. We performed in vitro tests to study the effects on aerodynamic prosthesis function when the prosthesis size-in particular, the inner diameter-was decreased. The effects on airflow and pressure were specifically studied in the airflow range of patients with laryngectomy. A 1-mm decrease of the regular inner prosthesis diameter from 5 mm to 4 mm showed no significant aerodynamic consequences at the average laryngectomized airflow point. Also, such a 1-mm decrease in diameter involved a prosthesis weight reduction of 18%. In view of these findings, downsizing the standard prosthetic diameter should be considered in future voice prosthesis development.

Dilatation, Pathologic↗
PubMed2004

Improved biomechanical resistance using an expanded polytetrafluoroethylene composite-structure prosthesis.

We designed a composite-structure (laminar-reticular) prosthesis using expanded polytetrafluoroethylene (ePTFE) as the biomaterial in an attempt to improve the biomechanical resistance of the same biomaterial in the form of a single lamina. Defects (7 x 5 cm) were created in the abdominal wall of male white New Zealand rabbits (n = 24). The defects, which comprised all the wall layers except the skin, were then repaired with one of two types of ePTFE prosthesis. One was a latest generation laminar prosthesis (DualMesh, or Gore-Tex) and the other was a composite of in-house design (CV-4 mesh composite) made by suturing a mesh woven out of ePTFE thread to an ePTFE lamina. After sacrificing the animals at 14 or 90 days after surgery, implant specimens were subjected to morphologic analysis (light microscopy and scanning electron microscopy); and adhesion formation, neoperitoneal thickness, and biomechanical strength were evaluated. No significant differences were recorded between the two prosthesis regarding the consistency of adhesions or the area occupied by adhesions (DM 0.17 +/- 0.06; CV-4 mesh composite 0.18 +/- 0.08 cm2) (p > 0.05). Notably, improved tissue integration was achieved using the composite prosthesis; its reticular side became infiltrated by dense connective tissue that enveloped the mesh filaments. In contrast, the DM prosthesis became encapsulated by host tissue. The neoperitoneum induced by both prostheses was homogeneous and orderly, with a layer of typical mesothelial cells lining its inner surface. The thickness of the neoperitoneum was similar (p > 0.05) for the two implants (385.0 +/- 3.4 vs. 390 +/- 3.1 microm), although significantly higher (p < 0.05) mechanical resistance values were recorded for the composite prosthesis (26.75 +/- 3.71 vs. 14.11 +/- 3.71 N). Our findings suggest that the use of a reticular and a laminar ePTFE layer in the same prosthesis leads to better repair and biomechanical behavior compared to the use of a single-structure laminar implant.

Abdominal Wall↗
PubMed1996

Left atrial spontaneous echo contrast in asymptomatic patients with a mechanical valve prosthesis.

BACKGROUND: Valve thromboembolism may be a fatal complication of mechanical valve prosthesis if detected late. Spontaneous echo contrast (SEC) is a well-documented prothrombotic phenomenon; here we report it in asymptomatic patients with a mechanical valve prosthesis. METHODS: Ninety-two asymptomatic patients with a mechanical valve prosthesis for underlying rheumatic heart disease underwent transesophageal echocardiography. Appendage area, peak filling and emptying velocities of the left atrial appendage, and the presence or absence of SEC and thrombi were determined. The results of 56 patients without SEC or thrombi (group I) were compared with those of 24 patients with SEC and no thrombi (group II) and 12 patients with thrombi (group III). RESULTS: Spontaneous echo contrast was present in 39% of the asymptomatic patients with a mechanical valve prosthesis. Although 12 patients had cardiac thrombi, including valve thrombi in 4, no patients presented symptoms. Anticoagulant therapy had no significant association with SEC and atrial thrombi. There was a significantly greater prevalence of atrial fibrillation and mitral prosthesis in groups II and III than in group I. Two patterns of left atrial appendage flow were identified: one was organized biphasic flow with peak filling velocities of 41.2 +/- 17.2 cm/s and emptying velocities of 40.5 +/- 17.5 cm/s. The other showed irregular, very low peak filling velocities (104 +/- 11.5 cm/s) and emptying velocities (12.3 +/- 13.1 cm/s). The former flow pattern was associated with sinus rhythm and the latter form was associated with atrial fibrillation. CONCLUSIONS: There was a relatively high prevalence of SEC and thrombi in patients with a mechanical valve prosthesis. Patients with a valve prosthesis may not have clinical symptoms. Anticoagulation intensity was not associated with the occurrence of SEC and thrombi. Patients with the mitral valve prosthesis and atrial fibrillation were identified as a high-risk of subgroup for the development of SEC and thrombi.

Adult↗
PubMed2004

[Revision total knee arthroplasty after unicompartmental femorotibial prosthesis: 54 cases].

PURPOSE OF THE STUDY: We analyzed technical difficulties encountered when performing revision total knee arthroplasty in patients with unicompartmental femorotibial prostheses. MATERIAL AND METHODS: This multicentric retrospective study included 54 revisions of unicompartmental femorotibial prosthesis with implantation of a total knee prosthesis. The series included 45 medial and nine lateral compartment prostheses. A gliding total knee prosthesis was implanted in 53 cases (98%) (39 standard, 14 revision). Mean time to failure of the unicompartmental prosthesis was four years. IKS scores were established at review. The radiological work-up included AP and lateral views in single leg stance and goniometry for 22 medial compartment revisions. Twenty-seven patients were seen for physical examination and x-rays and eight were lost to follow-up; data were recorded from medical files for 19 patients. RESULTS: The revision procedure was considered easy in 82% of the cases. Mean follow-up after revision was four years (range 2 - 12 years). Subjective outcome was very satisfactory for 56% of the patients, satisfactory for 36% and unsatisfactory for 8%. The mean function score was 62 points, the mean knee score 85 points, and the mean flexion was 113 degrees. No laxity was found for 90% of the knees. The femorotibial angle was 180 +/- 2 degrees in 46% of the patients. The mechanical femoral angle was 90 degrees in 54% of the patients with 2-4 degrees varus in 42%. The mechanical tibial angle was 90 degrees in 46% of the patients with 2-8 degrees valgus in 37%. Complications included pulmonary embolism (n=2), mobilization under general anesthesia (n=3), arthrolysis (n=1), lateral vertical patellectomy (n=1), and secondary infection (n=1). There were five failures requiring changing the total knee prosthesis. DISCUSSION: Loss of bone stock raises specific problems during revision of unicompartmental knee prostheses. Loss of tibial bone is more frequent but it is more difficult to correct for loss of femoral bone. A gliding knee prosthesis is generally preferred for first intention revision. We recommend a long stem when the bone defect is important or involves loss of cortical bone. We have had good mid-term results with revision total knee prostheses after unicompartmental prostheses. Longer follow-up is needed. Poor results were obtained when revision was performed for persistent pain without a clearly defined cause. The presence or not of significant bone loss did not appear to affect outcome. The observation of medial laxity in case of failed lateral unicompartmental prostheses suggests a more constrained total knee prosthesis might be indicated. Compared with earlier series, our results with total knee prostheses after unicompartmental prostheses appear to be better than after tibial valgus osteotomy and also better than after total knee arthroplasty. Conversely, they would be less satisfactory than for primary total knee arthroplasty. The surgical procedure for revision total knee arthroplasty after unicompartmental prosthesis requires precision and skill but is not technically difficult.

Aged↗