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At least 433 records · Page 24Linked to original sources
PubMed1997

Prosthesis for aortic arch substitution.

BACKGROUND: The risk of neurologic complications in aortic arch prosthetic substitution is directly related to the duration of the circulatory arrest. The purpose of this article is to report the experiments on animals of a device for simplifying and quickening the vascular anastomosis in aortic arch substitution. METHODS: The device consists of expandable loops of stainless steel wire, sewn to the proximal end of a Dacron prosthesis. An actuating removable guide allows the stainless steel wire loops to be expanded and tightened, in such a way that the prosthesis diameter is varied, while maintaining a regular cylindric shape. The prosthesis end is then transformed into a rigid cylindrical ring, approximately half the maximal diameter in length, with a variable and controllable diameter. A composite graft was prepared, fitted with the expandable device at the distal end of the main prosthesis as well as at each end of the branches for the supraaortic trunks. Cardiopulmonary bypass was established by cannulation of the right atrium and left iliac artery. The prosthesis was positioned very easily and quickly during a brief hypothermic circulatory arrest; ascending aorta anastomosis was carried out by the standard technique after central nervous system reperfusion was resumed. Acute experiments were carried out in 5 swine. RESULTS: Four of 5 animals survived the procedure without detectable neurologic sequelae. At sacrifice the prosthesis was found to be properly sited without lumen distortion or thrombosis. CONCLUSIONS: The main advantages of this device and modality of arch substitution in a clinical setting would include drastic reduction of the circulatory arrest time, easy and reliable hemostasis of the anastomosis line, and accurate and firm approximation of the dissection layers in case of dissecting aneurysms.

Animals↗
PubMed2000

[Replacement of prosthesis of the penis].

OBJECTIVE: To analyze the series of patients who underwent replacement of their penile prosthesis between years 1990 to 1999, due to any kind of complication. MATERIAL AND METHODS: 85 patients underwent implantation, 13 different prosthesis models being utilized. It was replaced (once or more) in 15 of these patients (17.64%). The mean age at the moment of the replacement was 51.5 years. The most frequent surgical approach was the infrapubic one. RESULTS: A total of 32 prosthesis-replacement interventions were carried out. The main causes were: mechanical failure (13 cases, 40.62%); infection (10 cases, 31.25%); and corpus cavernosum perforation (five cases, 15.62%). Progressive increase of complications incidence with regard to the ordinal number of the implanted prosthesis was not observed. Best overall results: Mentor Mark II and AMS 700 Ultrex Plus. At present day, only eight (53.33%) out of 15 reimplanted patients use their prosthesis with normality. CONCLUSIONS: Those patients who undergo replacement of their penile prosthesis are potential sources for later complications. Their knowledge and proper handling is important in order to a progressive improvement of the final results, (above all if--such as our case--these ones are not suitable for conformity).

Adult↗
PubMed1999

A new concept for a metacarpophalangeal prosthesis: consequence on joint biomechanics.

OBJECTIVE: The purpose of this work was to establish whether surface replacement non-constrained prostheses can duplicate the normal biomechanics of the metacarpophalangeal joint. DESIGN: A series of mathematical models. BACKGROUND: A non-constrained prostheses has been designed for the replacement of the metacarpophalangeal joint. It uses the concept of surface replacement in that it attempts to replicate the anatomy of the original cartilage surfaces. The centre of rotation of the prosthesis is also sited at the same position as in the natural joint to maintain the balance between the flexor and extensor tendon forces, such that the prosthesis duplicates the biomechanics of the normal joint. Due to the unique dimensions of each joint that may present for surgery, the four sizes of prosthesis that are available for implantation may not always produce an exact replication of the joint kinematics. These situations were examined to establish whether the biomechanics of the joint can indeed be restored. METHODS: Mathematical models for each size of prosthesis implanted into a range of different sized metacarpophalangeal joints were developed. The prosthetic and cartilage surface profiles were compared and the balance between the tendon forces was examined. RESULTS: Differences in size that may occur between the surface profiles of the normal joint and prosthesis, together with any relocation of the centre of rotation, would have negligible effects on the normal joint biomechanics. CONCLUSIONS: All four sizes of the non-constrained prosthesis can duplicate the normal biomechanics of the joint and hence provide normal function.

Biomechanical Phenomena↗
PubMed2000

[Metacarpophalangeal prosthesis modeling. Comparison of stress factors in a normal and a prosthetic metacarpophalangeal joint using finite element analysis].

INTRODUCTION: Prosthetic replacement of the metacarpophalangeal joints of long fingers is a problematical technique for the surgeon. The aim of the present study was to examine and compare, by means of finite element analysis, stress distribution in a normal metacarpophalangeal joint and to compare this with the findings in a similar joint with a prosthesis in order to better determine the risk of aseptic loosening, and also to examine possible solutions to limit these risks. METHOD: Finite element modelling was carried out using Abaqus software. Various criteria were taken into account including anatomical data, stress distribution, mechanical characteristics of the materials used, and different positions of the phalanx. RESULTS: A comparison of the results showed two significant stress distribution factors, i.e., a reduction of normal stress in the cortical bone of the finger fitted with a prosthesis; and the appearance of a flexion moment which completely modified the stress distribution throughout the metacarpal and therefore also in the opposite phalanx. DISCUSSION: To reduce the risk of aseptic loosening, two solutions were proposed: a) to reduce Young's module. The problem which arises, as in the case of total hip prosthesis, is that of finding a material with a Young's module which is closer to that of cortical bone, and which at the same time has a high elastic limit and breakage point and good biocompatibility; b) to reduce the inertia of the prosthesis, which seems the more likely of the two propositions, as it is based on the results of the modelling. The inertia of the prosthesis on stress distribution can be reduced by modifying two parameters, namely by producing a hollow section and shortening the structure of the prosthesis.

Elasticity↗
PubMedDate not supplied

[Long-term results of the Blauth knee prosthesis--current status of hinged knee prostheses].

AIM: Currently there is widespread use of unconstrained knee arthroplasty even in severe deformities of the knee. In order to ascertain the value and future of constrained knee prostheses, we have assessed the results of the Blauth knee prosthesis and compared them with the results of unconstrained knee prostheses. METHODS: In a retrospective analysis we examined 227 Blauth knee prosthesis implantations performed between 1985 and 1997. Using endpoints of prosthesis removal, infection and aseptic loosening, the 10-year survivorship analysis was evaluated. RESULTS: The analysis shows a 10-year survivorship of 90.1 % using aseptic loosening or infection as an endpoint and 96.2 % using removal as an endpoint. CONCLUSION: The first designs of constrained knee prostheses were associated with a high failure rate, while more recent designs like the St. Georg knee prosthesis and the Blauth knee prosthesis show long-term results similar to condylar designs. Since there has been a large increase of knee endoprosthesis implantations in the last years, a constrained knee prosthesis with excellent long-term results remains a valuable implant in cases of revisions and difficult knee arthroplasty.

Arthroplasty, Replacement, Knee↗
PubMedDate not supplied

[Clinical course of a late aseptically loosened PCA hip prosthesis shaft].

The surface of the proximal part of a PCA endoprosthesis stem in total hip replacement is structured with small beads to provide good conditions for bone ingrowth. The distal part of the stem has a smooth surface. For the mechanical fixation concept, this means anchorage of the proximal part and free axial mobility of the distal part of the prosthesis. We present a clinical case in which bone remodeling processes finally led to complete loosening of the prosthesis. The described mechanism of loosening could be reconstructed by radiological findings, bone scan, two digital subtraction arthrographies of the hip and by evaluation of the fibrous tissue formation around the stem after explanation. In this case, after an initial period of no measureable bone reactions, distal endosteal bone and proximal radiolucent space developed without loss of contact with the prosthesis. Later, a mechanical interruption between the proximal part of the prosthesis and bone occurred. There was no loosening of the distal part of the prosthesis at this time. Despite remarkable hypertrophy of the distal femoral bone, eventually the distal part of the prosthesis loosened so that a revision arthroplasty had to be performed. The described mechanism of loosening has not be proven to pertain to all such prostheses.

Bone Remodeling↗
PubMed2001

Cervical disc prosthesis in humans: first failure.

STUDY DESIGN: Prospective preliminary trial of a cervical disc prosthesis. OBJECTIVE: To study the feasibility, efficacy in maintaining intervertebral mobility, and complications of a low-profile disc prosthesis implanted after single-level cervical discectomy. SUMMARY OF BACKGROUND DATA: Since studies reported by Baba et al, there is fear that degeneration of the intervertebral disc levels adjacent to cervical arthrodesis may be exacerbated by this arthrodesis. For this reason, several cervical prostheses have been designed as an alternative to arthrodesis. None of these prostheses, some of which are bulky, has been shown to be efficacious. METHODS: Five women and five men (average age, 36 years) underwent implantation of the present disc prosthesis after single-level discectomy. The discectomy was performed for cervical disc herniation that resulted in cervicobrachial pain for more than 3 months. None of the patients exhibited intervertebral instability on bending films. Preoperative magnetic resonance studies showed a noncontained disc herniation in all 10 patients and osteophytes in 2 of the patients. RESULTS: The cervicobrachial pain resolved in all 10 patients. Intense neck pain developed in 1 patient who underwent revision surgery to remove the prosthesis and perform an arthrodesis. Another patient developed neck pain but refused the proposed revision operation. Bending films showed mobility of the intervertebral space containing the prosthesis in both of these patients. In the 8 patients who remained pain free after the operation, lateral bending films at follow-up found no mobility of the implanted disc level. Five of these eight patients had circumferential fusion, 2 had posterior fusion, and 1 had anterior fusion. CONCLUSION: This prosthesis failed to achieve the desired effect because the intended mobility failed to persist in 8 of the 10 patients and pain developed in the other 2 patients, in whom the mobility persisted.

Adult↗
PubMed2001

Intraoperative fabrication of palatal prosthesis for maxillary resection.

BACKGROUND: Immediate placement of a palatal prosthesis has become the standard of care after maxillectomy or palatectomy, except when free-flap reconstruction is used. Palatal prostheses are usually fabricated preoperatively. Infrequently, the surgeon may face a situation where upper jaw resection has been performed and a prefabricated prosthesis is not available. OBJECTIVE: To describe a method of rapid intraoperative fabrication of a palatal prosthesis, which allows immediate oral intake and excellent speech. PROCEDURE: Two sheets of thermoplastic dressing (Aquaplast; WFR/Aquaplast Corporation, Wyckoff, NJ) were immersed in hot water. As they became soft and pliable, they were applied to the remaining hard palate and alveolar ridge. As the material cooled, it hardened, with its shape conforming to the remaining hard palate, alveolar ridge, and teeth. The rigid stent was then removed, trimmed, and fashioned to cover the palatal and maxillary defect. The stent was then wired to the remaining alveolar ridge and to the ipsilateral zygomatic buttress or lateral orbital rim. Removal of the stent was easily accomplished in an office setting. PATIENTS: Twelve patients required partial upper jaw resection without available prefabricated prostheses. Of these, 3 patients underwent emergency surgery for mucormycosis and 2 for bleeding malignant tumors; 3 underwent bone resection more extensive than that anticipated preoperatively; and 4 did not have prefabricated prostheses for other reasons. RESULTS: The thermoplastic prosthesis achieved its goals in all 12 patients. Eleven patients achieved oral food intake within 24 hours. One patient remained in a coma after extensive maxillary, orbital, and skull base resection for mucormycosis. The prosthesis was removed after 4 to 12 weeks and replaced with a permanent implant in 11 of the 12 patients. CONCLUSIONS: This simple, quick, and inexpensive intraoperative fabrication of palatal prosthesis requires no special expertise and equipment. It allows immediate oral intake and excellent speech.

Carboxymethylcellulose Sodium↗
PubMed2001

Vascular collagen prosthesis of RaK type--long-term patency.

In 1990, the vascular prosthesis of RaK type (collagen-impregnated knitted prosthesis), produced by the Research Institute of Hosiery in Brno, was introduced into clinical practice. In 1998, we published our experience with this type of prosthesis in form of a clinical evaluating study performed according to the methods of the EN 540 European Norm. Now we inform about the results of the studied group followed during 3 years. The long-term patency of the prosthesis in the aortic-phemoral part is 88.8%; the incidence of infection of the vascular prosthesis in our group studied in the 3-year period is 2.5%. Thus we can say that even long-term results confirm our previous good experience with this vascular prosthesis produced in Brno. (Tab. 8, Fig. 1, Ref. 11.)

Aged↗
PubMed2004

[Assessing the transvalvular gradient of a Chinese-made jiuling solid pyrolytic carbon bileaflet heart valve prosthesis].

In order to assess the transvalvular gradient of a Chinese-made Jiuling solid pyrolytic carbon bileaflet heart valve prosthesis, we determined its hydrodynamics in the laboratory and then measured the hemodynamic performance in the animals and patiens. The Jiuling prosthesis was tested in a pulsatile flow simulator in the aortic position. Six sheep subjected to mitral replacement with 21 mm Jiuling prosthesis were measured by open cardiac catheterization intraoperatively. Doppler echocardiography and open cardiac catheterization under dobutamine stress were performed in two sheep 60 months after implantation. Clinically, 14 cases of aortic valve and 10 cases of mitral valve in the patients who underwent valve replacement with Jiuling heart valve prosthesis were measured by open cardiac catheterization and Doppler echocardiopgraphy. The results showed that Juiling heart valve prosthesis had lower mean transvalvular gradient (below 10 mmHg) at any given tissue annulus diameter. In animal experiments, the transvalvular gradients of 6 sheep were 5.2 +/- 1.7 mmHg intraoperatively, and of 2 sheep 60 months after implantation were 6.1 +/- 0.3 mmHg by catheterization. In patients, the mean transvalvular gradients in the aortic position measured by means of catheterization and echocardiography were 6.26-4.10 mmHg and 9.42-7.48 mmHg; the gradients in the mitral position were 2.10-1.9 mmHg and 5.281-4.10 mmHg respectively. The above results demonstrate that Jiuling valve prosthesis has excellent hemodynamic performance.

Adult↗
PubMed2006

[Analysis of complications after surgical voice and speech rehabilitation in laryngectomized patients. Problems related to implantation and change of voice prosthesis].

INTRODUCTION: Surgical rehabilitation of voice and speech, with implantation of Provox 2 voice prosthesis is becoming a standard procedure in Poland in the last few years. Still some opinions are raised, considering the potential risk of complications, particularly, when tracheo-esophageal puncture is finally located in the irradiated tissue. AIM OF THE STUDY: The assessment of safety, and analysis of complication encountered with tracheo-esophageal puncture, and implantation of voice prosthesis. MATERIAL AND METHOD: The 106 cases of patients treated with mentioned above method. The primary implantation was performed in 73 (68,9%) cases; the secondary implantation in 33 (31,1%). The 85 (80,2%) patients received radiotherapy before, or after implantation. In the analyzed period (2002-2004) apart of 106 implantations, the replacement of 132 prostheses was performed. RESULTS: There was only one, potentially life-threatening complication recorded in the analyzed group of 106 patients--inhalation of prosthesis to tracheo-bronchial tree. The most common complications directly related to implantation were: infection in the place of created fistula after secondary implantation 4/33(12,1%), and spontaneous partial extrusion of prosthesis with occlusion of created fistula tract 8/106 (7,5%). The average lifetime of prosthesis in place, was 9,8 months in irradiated field, and 9,7 months in patients who did not received radiotherapy. CONCLUSIONS: Surgical rehabilitation of voice and speech, with implantation of vocal prosthesis is safe and reliable procedure. The radiotherapy applied before or after creation of tracheo-esophageal fistula is not a contra indication for this method. Generally low rate of complications is similar in both groups--who does received or not received radiotherapy. Also the stability of implanted prostheses were similar in both groups.

Adult↗
PubMedDate not supplied

Magnet-retained facial prosthesis combined with an implant-supported edentulous maxillary obturator: a case report.

The prosthetic rehabilitation of maxillofacial defects is especially challenging when the patient is edentulous. Although dental implants are used to enhance the retention and stability of both facial and maxillary prostheses, combining facial and maxillary prostheses is extremely difficult. This article describes the prosthetic treatment of an edentulous patient with a large maxillary and facial defect. After placing dental implants in the remaining maxilla, a maxillary obturator prosthesis supported by a milled bar attachment was fabricated. The facial prosthesis was retained by a magnetic attachment to the maxillary obturator prosthesis. As the obturator prosthesis was supported securely by this sturdy attachment, the facial prosthesis was stable during mastication and facial movement. The patient reported improvement in prosthesis retention and stability. Both the masticatory and the speech functions of the patient improved.

Aged↗
PubMed1986

[Replacement of a failed total hip prosthesis].

At the present time, apart from infectious complication, failed total hip prosthesis essentially consist of detached prosthesis. On the basis of their experience of eight thousand arthroplasties, including more than 6,000 Charnley prosthesis, performed over a period of 18 years, the authors propose three basic principles designed to ensure a long term satisfactory result: steel on polyethylene prosthesis, diameter 22 and fixation with acrylic cement. They consider that this approach can offer a second chance to patients with a detached prosthesis, especially when the technique of the first arthroplasty was faulty or if a poor quality prosthesis was used. The authors' experience has confirmed that the second operation should aim to restore an arthroplasty as close as possible to normal anatomy. The authors have satisfactorily achieved this aim by the wide use of homografts.

Hip Prosthesis↗
PubMed1993

Low friction total knee arthroplasty with the alumina ceramic condylar prosthesis.

This paper evaluates the failure and wear properties of the alumina ceramic posterior cruciate condylar total knee prosthesis, and reports the preliminary clinical results of this prosthesis. Thirteen sets of the alumina ceramic prostheses were used for destruction and wear tests. The average ultimate load in the static destruction tests showed 2.63 x 10(4) Newtons in the femoral component, and 1.28 x 10(4) Newtons in the tibial component. The average ultimate energy in the impact destruction tests showed 22.1 Joules in the femoral components, and 20.3 Joules in the tibial components. The wear test demonstrated that the average depth of wear was 0.04 mm in the alumina ceramic prostheses, and 0.20 mm in the Vitallium prostheses. Observation of the UHMWPE wear surface with a scanning electron microscope indicated many deep scratches and a scooped concave lesion in the Vitallium prostheses; there were few deep scratches in the alumina ceramic prostheses. Thirty patients underwent 32 total knee arthroplasties using the alumina ceramic posterior cruciate condylar prosthesis between 1988 and 1990. The results were evaluated as excellent for 59%, good for 28%, fair for 10%, and poor for 3%. Critical roentgenographic review demonstrated no cases of loosening or sinking after arthroplasties using the alumina ceramic prosthesis. Radiolucent lines were observed only in 4 knees (12%) cases. All were observed around the tibial components, but were less than 1 mm in thickness. The frequency of the radiolucent lines is less than that observed in the Vitallium prosthesis at the same followup period. The alumina ceramic posterior cruciate condylar prosthesis may have sufficient durability and excellent wear properties for low friction total knee arthroplasty.

Aluminum Oxide↗
PubMed1994

[Directions for reoperation of patients with Björk-Shiley convexo-concave valve prosthesis, based on long-term experience].

Although a high incidence of strut fracture of the Björk-Shiley convexo-concave (C-C) valve prosthesis has been reported, it is still controversial whether the prosthesis functioning normally should be replaced electively. To clarify our policy for this issue, we reviewed 28 patients who had undergone mitral valve replacement with a C-C valve prosthesis, and evaluated long-term results according to STS guidelines. The incidence of valve-related complications expressed as % patient-year were; structural deterioration 0.30, nonstructural dysfunction 0.30, thromboembolism 1.20. There were no thrombosed valves, anticoagulant-related hemorrhage or prosthetic valve endocarditis. The actuarial free rate after valve replacement with the C-C at 10 years, constructed by the Kaplan-Meier method, were compared with those with St. Jude Medical (SJM) valve prosthesis. (1) Actuarial survival: 77.9 vs 87.3 (NS), (2) Reoperation-free: 91.6 vs 98.0 (p < 0.05), (3) thromboembolism-free: 83.7 vs 83.9 (NS), (4) Event-free (hospital death+reoperation+valve-related complications: 71.2 vs 77.7 (NS). The long-term results with the C-C were compatible to those with a SJM valve prosthesis. However, if a strut fracture occurs, it is very difficult to save the patient's life. The hospital mortality of re-replacement of valve prosthesis during the last 10 years, at our institute, was 2.6%, which is almost equal to the cumulative risk of strut fracture of the C-C valve after 10 years (3.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Long-term followup of and patient satisfaction with the Dynaflex self-contained inflatable penile prosthesis.

PURPOSE: We analyzed our experience with the Dynaflex* self-contained inflatable penile prosthesis to define specific complication rates and patient satisfaction in the long term. MATERIALS AND METHODS: From October 1990 through October 1994, 62 men underwent implantation of a Dynaflex prosthesis. Mean and median time since implantation was 50 and 53 months, respectively (minimum 24). In addition to standard followup and tabulation of complications, patients were contacted and interviewed regarding satisfaction with the prosthesis. RESULTS: Mechanical device failures occurred in 9.7% of cases with a mean time to failure of 40 months in 6 prostheses. An additional 16.1% of patients had an unsuccessful outcome due to dissatisfaction with the Dynaflex. Of the patients with a functional Dynaflex prosthesis contacted at the time of this review 88.1% expressed satisfaction. CONCLUSIONS: Mechanical failure rates for the Dynaflex prosthesis are comparable to those previously reported for multicomponent inflatable penile prostheses. Patient dissatisfaction, mainly due to difficulty in operating the Dynaflex inflation and deflation mechanisms, is much higher than for multicomponent inflatable penile prostheses. However, in patients who are successful in mastering operation of the Dynaflex satisfaction rates are high. Careful patient selection, and extended training and education efforts are the keys to maximizing successful outcomes with the Dynaflex prosthesis.

Adult↗
PubMed1998

[Complications from the hinged GUEPAR prosthesis after resection of knee tumor. 102 cases].

PURPOSE: The purpose of this study was to present the complications which occurred in knee replacement with the GUEPAR prosthesis, after bone tumor resection. We tried to point out complications in relation to prosthetic design and surgical technique. MATERIAL AND METHOD: Between 1972 and 1993, 90 patients had a knee resection, for 80 malignant and 10 benign tumors. There were 51 males and 49 females, aged 12 to 75 years (mean age 35). Fifty-six distal femur resections and 34 proximal tibial resections were performed. Length of resection averaged 16 cm (9 to 30). The reconstruction was always achieved with a cemented, custom-made GUEPAR prosthesis. Including revisions, there was a total of 102 prostheses in 90 patients. A patellar resurfacing was performed in 64 cases. An allograft reconstruction was associated in 39 knees. In all tibial resections and in two extra-articular femoral resections, the extensor mechanism had to be reconstructed. Several reconstruction techniques were associated, in which 19 medial gastrocnemius transfers. The prosthesis design was slightly modified with time. Ten patients received radiotherapy, and 55 had chemotherapy. RESULTS: Results and complications were retrospectively assessed, with an average follow-up of 4.3 years (1 to 22). Six patients were lost for follow-up, 62 patients were alive, with no evolutive disease, 13 had an evolutive disease and 10 were deceased from disease. Nineteen patients had distant metastasis and 17 had local recurrences. Apart from intraoperative complications, late mechanical complications included: 13 aseptic loosening, 2 femoral shaft fractures, 18 knee contractures, 5 femoral stem fractures and, 18 intra-articular instabilities related to wear of the hinge-axis. In the 39 allograft-composite prostheses, only 15 had a favorable evolution. There were 15 extensor mechanism failures and 13 knees had persistent infection. There was a total of 94 reoperations in the 90 patients. In 28 cases, the initially implanted prosthesis was removed. There were also 18 revisions, 7 amputations and 3 arthrodeses. Survivorship analysis showed a 60 per cent probability for the initial prosthesis not to be revised at 10 year-follow-up, apart from oncologic complications. DISCUSSION: Results with allograft-composite reconstruction were not better than with massive prosthesis. When needed, soft tissue coverage and patellar tendon augmentation would better be performed with gastrocnemius plasty. Polyethylene and steel bushes were not solution for hinge axis wear.

Actuarial Analysis↗
PubMed1994

Femoral prosthesis implantation induces changes in bone stress that depend on the extent of porous coating.

The objective of this study was to evaluate the effect of implantation of porous-coated anatomic medullary fitting prostheses on stress in the proximal femur. Three-dimensional finite element models of a cadaveric femur before and after implantation were used to evaluate the resulting changes in stress in the bone. Models of the femur were generated automatically from computed tomographic scan data with use of an innovative mesh-generation technique. The models were analyzed for three levels of porous coating (proximal, 5/8, and full), with the assumption of ideal ingrowth (perfect bonding) over porous areas and a frictionless, tension-free surface on smooth areas. All models were loaded and restrained to represent conditions of normal gait. The stresses predicted in the implanted femur are consistent with clinical observations of proximal cortical atrophy (normal stress reduced to 6-9% of normal at the calcar and 50-55% at mid-prosthesis) and of hypertrophy at the porous coating junctions (normal stress at the 5/8-coating junction, 123% of stress proximal to the junction) and hypertrophy near the distal tip of the prosthesis (anterior and posterior normal stresses 200-800% of normal). The fully coated prosthesis induced stresses in the bone near the tip of the prosthesis that were most like stresses in the normal femur (medial and lateral normal stress 105 and 102% of the stress in the normal femur). Below the collar, the normal stress associated with the proximally coated prosthesis was 6% greater than that produced with the other two levels of coating but still was only 2% of normal. The 5/8-coated prosthesis appeared to combine the worst features of the fully coated and proximally coated prostheses--greater stress-shielding at the calcar and higher stress near the tip of the prosthesis.

Artificial Limbs↗