Showing papers on "Prosthesis published in 1986"

The influence of tibial-patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis

Abstract: Function of the knee and patellofemoral symptoms were correlated with the position of the implant in 101 consecutive patients with 116 posterior stabilized condylar knee prostheses. All of the patients were followed for a minimum of two and a half years with sequential physical examinations, radiographs, and functional evaluation of the knee. In sixteen knees (14 per cent), clicking or catching of the patella in terminal extension or painless crepitation throughout the arc of flexion developed without lowering the functional knee-evaluation score. Pain or mechanical problems, or both, that lowered the functional knee-evaluation score occurred in another fourteen knees (12 per cent), within the first postoperative year. Of these fourteen, eight required revision solely for patellofemoral complaints. Critical analysis of the tibial-patellofemoral mechanical axis identified three surgical variables that were found to markedly affect the functional result of the prosthesis: the distance from the center line of the tibial prosthesis to the center line of the tibial plateau, a change in the position of the joint line of the prosthesis relative to the hip and ankle, and the patellar height, measured as the perpendicular distance from the inferior pole of the patellar implant to the joint line of the prosthesis. Functional knee scores, range of motion, patellofemoral pain or mechanical symptoms, the need for revision, and the necessity of manipulation could all be statistically significantly correlated with the three independent variables. In addition, a range of neutral alignment was developed.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival of knee arthroplasties. A nation-wide multicentre investigation of 8000 cases

Abstract: A prospective nation-wide study of knee arthroplasty has been under way in Sweden since October 1975. By the end of 1983, 4505 arthroplasties for osteoarthritis and 3495 for rheumatoid arthritis had been recorded and reviewed one, three and six years after the operation. Using actuarial methods, the probability of the prosthesis remaining in situ after six years was calculated. In osteoarthritis this probability ranged from 65% for hinged prostheses to 90% for medial compartment prostheses. Two-and three-compartment prostheses produced intermediate results with 87% survival. In rheumatoid arthritis the probability varied from 72% for medial compartment prostheses to 90% for two- and three-compartment prostheses. The main reason for failure was loosening of the components, the second most common was infection. The probability of revision for infection by six years was 2% in osteoarthritis and 3% in rheumatoid arthritis. Most revisions were to a three-compartment prosthesis. Knee fusion at primary revision was required in 2% of the cases at six years.

Treatment of femoral neck fractures with total hip replacement versus cemented and noncemented hemiarthroplasty.

Abstract: A prospective study of displaced femoral neck fractures was conducted with patients randomized into three groups: cemented total hip replacement (THR), cemented hemiarthroplasty (UHR-C), and noncemented hemiarthroplasty (UHR-NC). Eighty-nine patients were treated for displaced (Garden type 3 or 4) fracture with a prosthesis; 39 patients had THR, 37 had UHR-C, and 13 had UHR-NC. No difference was found in the level of pain, ambulation, or aids required between the THR group and the UHR-C group, except for active community ambulators, who demonstrated decreased endurance capability when treated with UHR-C. The patients treated with UHR-NC had increased pain and decreased ambulation and required assistive devices. The most significant complication was dislocation, which occurred in 7 patients with THR and 2 with UHR-C. The mortality rate at 2 years was 18%; all but two of the deaths were in patients with one of five different medical diseases: clinically significant cardiac or pulmonary disease, cancer, alcoholism, or psychosis. The mortality rate was insignificant in patients younger than 70 years of age. Roentgenographic review showed only 2 of 76 cemented stems with progressive cement-bone demarcation, with one patient requiring revision for a loose prosthesis. No evidence of protrusio was seen with the use of the bipolar cap. The uncemented hemiarthroplasties demonstrated lucency between the metal and bone in the proximal femur in 9 of 13 stems. The authors make recommendations regarding hip replacement.

Micromotion in knee arthroplasty. A roentgen stereophotogrammetric analysis of tibial component fixation.

Abstract: The modern era of endoprosthetic joint replacement started with the introduction of acrylic cement to improve component fixation. Long-term results have, however, indicated that prosthetic fixation remains critical; loosening at the bone-cement interface has become an important problem. Research in recent years has focused on attempts to achieve better fixation by improving cementing techniques, improving prosthetic design by, for example, adding metal support of polyethylene components and by exploring alternative ways to bond prosthetic components to bone without cement. The mechanical integrity of the bone-cement interface has been studied under laboratory conditions. Because of the in-vivo reaction of bone, with the interposition of a fibrous tissue layer at the interface, such studies are not totally valid. Studies on autopsy material, more closely resembling the in-vivo situation, are few and there has been only one previous study like the present one. In this study, roentgen stereophotogrammetric analysis (RSA) was evaluated and found to have an accuracy ten times better than conventional radiography. This accuracy was judged adequate for studies of micromotion. In this work, two types of micromotion of the tibial component were studied; migration, i.e. gradual motion over time, and inducible displacement, i.e. instant motion in response to external forces. Ninety-six knee arthroplasties for gonarthrosis, representing four different types of fixation were studied by roentgen stereophotogrammetric analysis (RSA). Eighty-nine arthroplasties were clinically successful. The follow-up ranged from two to five years. Full post-operative weight-bearing was allowed for all patients, except those operated with a Freeman-Samuelson prosthesis, who were adviced to use crutches for six weeks and partial weight-bearing for another six weeks. Fifty-one conventionally cemented all-polyethylene prostheses, 27 total and 24 unicompartmental, represented a baseline series. Migration was found for all prostheses, with a mean maximum deflection of 1.2 and 0.9 mm, respectively, after four years. In both groups, the major part of the migration occurred during the first year, after which the majority of the components did not migrate further. Some prostheses, with larger migration during the first year, continued to migrate throughout the investigation. None of the total, but the majority of the unicompartmental prostheses showed signs of cold flow within the polyethylene. All prostheses showed reversible inducible displacement, the maximum deflection ranging from 0.2 to 1.0 mm.(ABSTRACT TRUNCATED AT 400 WORDS)

Prosthetic use in adult upper limb amputees: a comparison of the body powered and electrically powered prostheses

Abstract: Three hundred and fourteen adult upper limb amputees were reviewed retrospectively at the Ontario Workers' Compensation Board. A questionnaire was used to evaluate the use of body and electrically powered prostheses. Follow-up ranged from 1 to 49 years with a mean of 15 years. Results indicated that complete or useful acceptance of an electrically powered prosthesis was reported by 69 of 83 amputees (83%); 199 of 291 amputees (68%) used the cable operated hook, 57 of 291 (20%) used the cable operated hand and 40 of 83 (48%) used the cosmetic prosthesis. The majority of amputees used more than one prosthesis for their functional needs and should be fitted with more than one type of prosthesis. Acceptance of an upper limb prosthesis by 89% (196/220) of below-elbow, 76% (56/74) of above-elbow and 60% (12/20) of high level amputees indicates that for most upper limb amputees, their prostheses are well used and essential to their personal and employment activities.

A modular femur-tibia reconstruction system.

Abstract: A 26 piece modular system for the reconstruction of the bones of the lower extremity from the femoral head to the distal third of the tibia is described. This modular system can be implanted without cement and allows for the intraoperative determination of the amount of resection necessary. The implant material is the well-known cast, Co-Cr-Mo alloy Vitallium. From 1982 to the end of 1985, 52 patients were treated with this cementless tumor endoprosthesis of the Kotz Modular Femur-Tibia Reconstruction System (KMFTR) at the University of Vienna, Department of Orthopedics. The locations of the tumors were: proximal femur (28), distal femur (17), and proximal tibia (7). In two cases a total femur was implanted and in another patient a total knee. Indications for the resection of the bone segments and joints concerned included primary bone tumors, metastases, and loosening of conventional endoprostheses and tumor resection endoprostheses. Twenty-one patients with an average follow up of 20.4 months and a minimum follow up of 1 year were evaluated according to Enneking's criteria. Eight patients had proximal femoral replacement. The results were excellent in two, good in five, and fair in one. Eleven patients had undergone replacement surgery in the knee joint area. The overall rating showed five excellent results, four good and two fair. One patient with a total femoral replacement had multiple bone metastases with polytopic pain and was no longer available for regular assessment. Another patient with a total knee replacement suffered a rupture of the patellar ligament after 10 months and had to be revised. Radiologically we have observed excellent bone incorporation of the prosthesis in 15 of 25 evaluated patients. Ten cases showed no changes in radiologic features as compared to the initial findings. These were patients with short follow up periods. Although complications did occur in these major surgical interventions, the final results were very satisfactory and the patients were subjectively content with the operation.

Asymptomatic total hip prosthesis: natural history determined using Tc-99m MDP bone scans.

Abstract: A prospective study was performed with 97 patients who had undergone total hip replacement surgery and who were not experiencing pain or other symptoms or problems. The study was intended to determine the normal postoperative appearance of radionuclide scans of the hip following administration of technetium-99m methylene diphosphonate. Five areas of the prostheses were evaluated. Results showed that 6 months after implantation activity around the lesser trochanter and prosthesis shaft became insignificant. Activity around the acetabulum, greater trochanter, and prosthesis tip stabilized approximately 2 years after surgery; approximately 10% of patients in the study had persistent activity in these areas. Familiarity with this normal progression is fundamental to interpretation of postoperative bone scans in patients with total hip prosthesis.

A prospective evaluation of the Björk-Shiley, Hancock, and Carpentier-Edwards heart valve prostheses.

Abstract: From 1975 to 1979, 540 patients undergoing valve replacement were entered into a randomized trial and received either a Bjork-Shiley (273 patients) or a porcine heterograft prosthesis (initially a Hancock valve [107 patients] and later a Carpentier-Edwards prosthesis [160 patients]). Two hundred and sixty-two patients required mitral valve replacement, 210 required aortic valve replacement, 60 required mitral and aortic valve replacement, and eight also required associated tricuspid valve replacement (six mitral valve replacement; two mitral plus aortic valve replacement). Analysis of 34 preoperative and operative variables showed the treatment groups to be well randomized. In-hospital mortality was not significantly different among patients receiving the three prostheses for aortic valve replacement (7.6% overall) and mitral plus aortic valve replacement (10% overall), but there was a higher in-hospital mortality for patients undergoing mitral valve replacement with the Carpentier-Edwards prosthesis (15.5% compared with 8.8% overall; p = .03). This difference could not be explained on the basis of any preoperative or operative variable. Median follow-up was 5.6 (range 2.8 to 8.3) years. Actuarial survival after mitral valve replacement was 56.7 +/- 7.0% at 7 years, that after aortic valve replacement was 69.6 +/- 9.6% at 7 years, and that after mitral plus aortic valve replacement was 62.5 +/- 20.0% at 7 years. There was no significant difference in actuarial survival of patients receiving the three prostheses within the mitral, aortic, and mitral plus aortic valve replacement groups, nor was there a difference when these groups were amalgamated. Thirty-seven patients required reoperation for valve failure (15 with Bjork-Shiley, 12 with Hancock, and 10 with Carpentier-Edwards valves; p = NS) and 11 died at reoperation (four with Bjork-Shiley, four with Hancock, and three with Carpentier-Edwards valves; overall operative mortality 29.7%). Up to 7 years after surgery, there was no significant difference in the incidence of thromboembolism in patients with different prostheses undergoing mitral or aortic valve replacement. There were too few patients undergoing mitral plus aortic valve replacement for meaningful comparison. There was no significant beneficial effect of anticoagulants in patients undergoing mitral or aortic valve replacement with porcine prostheses, but patients were not randomly allocated to anticoagulant treatment. All patients with Bjork-Shiley prostheses received anticoagulants.(ABSTRACT TRUNCATED AT 400 WORDS)

Tissue reactions to titanium endoprostheses. Autopsy studies in four cases.

Abstract: Four cementless prosthetic hip implants of Ti-6Al-4V-alloy with and without longitudinal grooves and Al2O2 ceramic ball heads, with implant periods of 3, 4, 5, and 10 months, were sectioned and examined histologically in undecalcified thin ground sections. Especially on the medial and lateral sides of the prostheses, there was direct bone-to-metal contact without interposed connective tissue, spreading to the dorsal and ventral areas of the prosthesis shaft, which was considered osseointegration. This is based mainly on the technique of implantation with primary stability in the cortical bone by press-fit and on the bioinertness of the titanium alloy. Ungrooved prosthesis areas seem to favor bone growth at the shaft. The secondary bone ring, occurring on the dorsal and ventral areas of the prosthesis, with evidence of further bone remodeling with the passage of time, indicates that osseointegration is a dynamic process that continues to improve prosthetic stability.

Indium-granulocyte scanning in the painful prosthetic joint.

Abstract: The value of indium-111-labeled granulocyte scanning to determine the presence of infection was assessed in 50 prosthetic joints (41 of which were painful) in 40 patients. Granulocytes were obtained from the patients' blood and labeled in plasma with indium 111 tropolonate. Abnormal accumulation of indium 111 in the region of the prosthesis was noted. Proven infection occurred in 11 prostheses, and all of the infections were detected by indium-111-labeled granulocyte scanning. Nineteen were not infected (including nine asymptomatic controls) and only two produced false-positive scans. This represents a specificity of 89.5%, sensitivity of 100%, and overall accuracy of 93.2%. These results compare favorably with plain radiography. There was no radiologic evidence of infection in three of the infected prostheses, and 10 of the noninfected prostheses had some radiologic features that suggested sepsis. We conclude that indium-granulocyte scanning can reliably detect or exclude infection in painful prosthetic joints and should prove useful in clinical management.

Prosthetic assembly for the knee joint

Abstract: The object of the invention relates to the technical field of medical sciences. The assembly comprises, for each knee, six types of prosthesis which are specially adapted to the lesion to be treated, a basic trochleo-bicondylar monobloc prosthesis of which the shapes and profiles are determined in order to be adapted to the anatomy of the knee particularly the femoral condyles; an external trochleo-condylar prosthesis, an internal trochleo-condylar prosthesis, a rotular prosthesis, a mono-external prosthesis, a mono-internal prosthesis, each of these prostheses presenting according to the type one or a plurality of parts having the same shapes and profiles as those of the basic trochleo-bicondylar prosthesis.

Prosthetic arthroplasty in recent and old complex injuries of the shoulder

Abstract: Thirty-four acute and 22 old injuries of the shoulder have been operated on, using either a humeral prosthesis (24 cases) or a total Neer prosthesis (32 cases). The mean age of the patients was 66 years. There were 32 acute and 13 old four-part fractures of the upper end of the humerus and 6 dislocations of the shoulder. The surgical technique and the method of rehabilitation are described. There were 17 post-operative complications, including 4 dislocations, 2 cases of secondary displacements of bone fragments and 2 loosenings of the glenoid component. In only 4 cases was a further operation needed. The results were analysed in 43 cases with a follow-up greater than one year. In 34 cases, there was no pain, but only 17 cases had more than 90 degrees of active flexion. There were no loosenings of the humeral stem. In two cases of humeral replacement, a narrowing of the joint space was noted. There was moderate peri-articular ossifications on 6 occasions. An upward displacement of the prosthesis was noted on 10 occasions, due to rupture of the rotator cuff. The results were much better in acute lesions than in chronic ones. The authors conclude that prosthetic replacement is indicated in severe fractures of the upper end of the humerus, whether acute or chronic, and if the patient is elderly.

Revision of infected knee arthroplasty

Abstract: Sixteen infected knee arthroplasties were revised and followed for 5 (1-10) years. There were nine recurrences of infections, but in one of these a second revision was successfully carried out. The remaining seven revisions resulted in only four functioning prostheses. The results were poor for hinged and stabilized prostheses for which arthrodesis, after eradication of the infection, is recommended. Infected compartmental prostheses with good bone stock could be treated with a two-stage procedure using tricompartmental revision prostheses.

Silastic arthroplasty in rheumatoid MCP-joints.

Abstract: Resection arthroplasty using Swanson silicone prosthesis was performed in 74 MCP-joints in 22 patients, all with rheumatoid arthritis. Follow-up at 2 (1-7) years showed complete pain relief in 15 patients and considerable improvement in hand function; the average range of motion was unchanged but extension was improved and ulnar deviation and volar displacement were reduced. Complications included fracture of four implants, two superficial infections, one hematoma and one skin necrosis.

Non-inflatable penile prosthesis for the management of urinary incontinence and sexual disability of patients with spinal cord injury

Abstract: During the last 5 years non-inflatable penile prostheses were implanted in 37 patients with spinal cord injury. Operation was done to provide adequate stability of the penis in order to hold an external urinary device, to help erectile impotence and to make self-catheterisation easier. A pair of Shirai-type silicone penile implants were inserted into the corpora cavernosa through a dorsal skin incision at the penile base. In 37 patients 33 had excellent results. Extrusion of the prosthesis occurred in two cases due to infection. Removal of the prosthesis was necessary in a patient who had causalgia in the lower extremities. Posterior migration of the prosthesis was noted in a tetraplegic patient who used to turn on his stomach when he changed clothes. Anterior sphincterotomy which was performed during the surgery in one case and after the surgery in another two cases did not affect the prosthesis. Questionnaire survey revealed that 32 (86%) were satisfied with the procedure which provided better condom fitting and easier intermittent catheterisation whereas only 5 (14%) were dissatisfied. The prosthesis improved sexual function in 15 (41%) patients, 18 (48%) patients were unchanged and four (11%) patients were dissatisfied. Penile prosthesis is an effective manoeuvre for the treatment of urinary incontinence and sexual disability of patients with spinal cord injury provided that the special aspects of the spinal cord injury is taken into consideration.

Evaluation of the Noiles hinged knee prosthesis. A five-year study of seventeen knees.

Abstract: The Noiles hinged knee prosthesis has been reported to diminish sheer and tensile loading on the cement-bone interface. Theoretically, this should eliminate the complication of loosening, commonly reported in hinged total knee prostheses. We reviewed the cases of all of the patients who have been treated with the Noiles knee prosthesis at our institution. Eighteen knees in fourteen patients were available, seventeen of which were followed for more than five years. Although all of the prostheses did well initially, ten knees in eight patients (56 per cent) had failed by an average of thirty-two months postoperatively. These eight patients included four of the five who weighed more than ninety kilograms and all of those who had had a prior arthroplasty. The failures were clearly defined along the lines of sex distribution. Measurements on the radiographs showed a significant difference between sexes in the metaphyseal diameter and thus in the percentage of the femoral canal that was filled by the prosthesis and cement. We concluded that prosthetic design must incorporate cortical cement support to reduce stress at the cement-bone interface, especially in a medullary canal with a larger diameter.

Conventional versus resurfacing total hip arthroplasty: a long-term prospective study of concomitant bilateral implantation of prostheses

Abstract: Fifty patients requiring bilateral total hip arthroplasty underwent a concomitant conventional hip arthroplasty on one side and an articular resurfacing procedure on the other, done by the senior one of us (M. A. R.). The average age of the patients was sixty-two years (range, twenty-one to eighty-seven years), and forty-seven of them were followed with serial radiographs and clinical evaluation for one year or more. The length of follow-up was five years for thirty-four patients with both prostheses intact. The average pain score for all hips at three years postoperatively was 5.5 points. Although the majority of patients at each follow-up interval did not prefer one procedure to the other, the conventional arthroplasty was significantly superior for those who had a preference, and radiographic evaluation revealed a statistically significant increased incidence of acetabular lucency at the bone-cement interface of the resurfacing arthroplasty at one, two, three, five, and seven years postoperatively (p less than 0.002). Two of the conventional prostheses were revised during this time-period (one because of infection and one, a broken stem) whereas thirteen (26 per cent) of the resurfacing prostheses were revised (eight hips had femoral loosening, five with concomitant acetabular loosening; three had acetabular loosening; and one had a femoral neck fracture) at an average of fifty-two months postoperatively (p less than 0.001).

Long-term follow-up of prosthetic joint replacement in hemophilia.

Abstract: We evaluated the outcome of seven severe hemophilic patients who underwent four total hip and four total knee arthroplasties since 1976. These patients have been followed at regular intervals over a period of 2.5-9.5 years (mean 5.8). Of the four total hip replacements, one had to be removed because of loosening and secondary infection 3 years after the initial surgery but was salvaged by pseudoarthrosis; the other three are pain-free and radiologically stable and have an excellent range of motion 2.5, 5, and 7 years postoperatively. Of the four total knee replacements, one had to be removed because of infection but was successfully salvaged by arthrodesis; one patient has loose components, but the prosthesis is still functional; and the final patient with bilateral knee prostheses is pain-free with limited but functional range of motion. Clotting-factor replacement therapy was effective in controlling intraoperative bleeding, even in a patient with an inhibitor, and only one procedure was complicated by hematoma formation. We conclude that prosthetic joint replacement may be safely performed in hemophilic patients but should be reserved for those who have limited function because of severe pain, joint destruction, and deformity. Total hip arthroplasty is as successful in these patients as in nonhemophiliacs. Total knee arthroplasty provides relief of pain, reduces the frequency of hemarthroses, and corrects most of the deformity, but it is usually associated with a limited range of motion.

Management of the upper-limb-deficient child with a powered prosthetic device.

Abstract: A long-term survey of a large number of children fitted with an electrically powered upper-limb prosthesis seems not to have been reported in the literature. Children with upper-limb deficiencies (congenital or traumatic) were fitted with an electrically powered upper-limb prosthesis in Ontario during the 18-year period of 1965-1983. Seventy-eight patients responded to a questionnaire or were interviewed by telephone. The dropout rate in children with a below-elbow amputation was similar to that reported in below-elbow child amputees wearing a conventional body-powered prosthesis (10% vs. 13%). The acceptance rate in children with above-elbow amputations was higher in those wearing an electrically powered prosthesis than in those using the conventional prosthesis, testifying for improved prosthetic function in the former group.

Titanium fibermetal segmental replacement prostheses. A radiographic analysis and review of current status.

Abstract: Thirteen patients with titanium fibermetal segmental bone/joint prostheses at a minimum follow-up period of six months were reviewed. Detailed radiographic data were analyzed quantitatively in terms of stem/bone interface radiolucency and bone bridging over the segmental portion of the prosthesis at predefined zones. Although stem radiolucent lines were common in this series, only one case had clinical loosening and required reoperation. There were two cases of stem fracture; one achieved extracortical bone union without revision, and the other case required implant removal and revision. Analysis of the retrieved specimen revealed histologic evidence of bony ingrowth. The use of a long side plate for initial implant fixation might have been partially responsible for this complication because of inhibition of new bone formation over the porous-coated segment. Sequential study of radiograms at different follow-up time periods with the same zonal analysis criteria revealed that no progression of radiolucency occurred at the bone/prosthesis interface, and bone formation over the segmental portion either increased or stabilized with time. The patients' functional results and implant performance seemed to indicate that the porous-coated segmental prosthetic system was effective in bridging skeletal/joint defects. However, further improvements are needed in prosthetic design and implant quality control in order to minimize device-related complications.

Knee arthroplasty at the London Hospital. 1975-1984.

Abstract: In the past ten years, three related prostheses (Freeman-Swanson, ICLH, Freeman-Samuelson) have been used at the London Hospital. The new findings reported in this article are the result of cementless fixation of the ICLH prosthesis has not deteriorated with time; the patellofemoral complications and postoperative limitation of movement seen with the ICLH prosthesis has been resolved by the Freeman-Samuelson design; and cementless press-fit fixation of all three components of the Freeman-Samuelson design resulted in a 1.6% (tibial) revision rate in the first four years.

Long-term follow-up of metacarpal phalangeal arthroplasty with silicone Dacron prostheses

Abstract: Sixteen patients who had eighty-nine metacarpal phalangeal arthroplasties with silicone Dacron prostheses (Niebauer type), were followed for an average of 11 1/2 years. Evaluation for palmar subluxation, ulnar drift, range of motion (ROM), pain relief, and stability showed it was satisfactory for relief of pain and correction of ulnar drift but it was eventually poor for range of motion and stability. If the arthritis was not controlled, the function of the hand decreased progressively, in spite of prosthetic replacements of the joints.

A humeral modular prostheses for bone tumour surgery: a study of 56 cases

Abstract: Fifty six humeral prostheses were inserted from 1974 to 1984 for primary bone tumours of the shoulder. In 40 patients a proximal humeral resection was performed and in the remaining 16 cases a Tikhoff-Linberg procedure was employed. The length of humeral resection ranged from 9 cm to 24 cm. A detailed analysis of the oncological and functional results was made. The resection was well clear in 42 patients (75%), marginal in 12 (21.5%), and through tumour in 2 (3.5%). Eight local recurrences were noted. The functional results were satisfactory, the patients having a wide range of active rotation and being able to do sedentary work. A new modified humeral modular prosthesis was introduced in 1984 and is presented.

Electron beam irradiation after reconstruction with silicone gel implant in breast cancer.

Abstract: Irradiation for breast cancer in the presence of a silicone gel breast prosthesis is sometimes necessary. There is a concern among radiation and other oncologists as to whether the presence of the prosthetic implant would interfere with delivery of the needed irradiation doses. Electron beams, with their finite penetration and rapid fall-off, offer a mode of adequately treating the recurrence and minimizing the radiation to the underlying normal structures, such as the lung and the heart. The dose distribution using 9-20 MeV electrons in the presence of a breast prosthesis is compared to the dose distribution without the implant in a tissue equivalent water phantom. The results reveal no significant difference in the dose delivered due to the presence of the prosthesis. Clinical verification of the dosimetry in the presence of the prosthesis confirmed that the presence of the silicone gel implant does not compromise treatment by irradiation in the management of breast cancer.

Long-term experience with biocompatible ossicular implants.

Abstract: The senior author's 8-year personal experience with biocompatible ossicular implants is reviewed. Four hundred sixty-one consecutive operations, in which high-density polyethylene sponge ossicular replacement prostheses were used, are grouped according to the Bellucci classification of chronic otitis media. The prostheses used were the drum-to-footplate prosthesis (TORP, total) and the drum-to-stapes prosthesis (PORP, partial). Each group's short- and long-term hearing results are compared. Prosthesis extrusion and persistent or recurrent conductive hearing loss are the most common causes of operation failure. Failures within each group are analyzed, and techniques to prevent these complications are outlined.

Direct comparison between bilaterally implanted cemented and uncemented total hip replacements in six patients.

Abstract: Six simultaneous bilateral total hip arthroplasties were performed with an ingrowth prosthesis in one hip and a conventional cemented prosthesis in the contralateral hip. Clinical and radiographic examinations of the patients were obtained for a maximum of three years for an early comparison of the two prostheses. Although no functional difference was established between the two arthroplasties, all patients preferred the cemented hip because of less pain and no limp. Range of motion and functional ability of the hips were identical in all evaluations. Pain was slightly higher in the hip incorporating the ingrowth prosthesis, and walking ability was better with the cemented hip. No radiolucency was evident around the cemented femoral component or around either acetabulum in any of the patients. Half of the patients encountered initial subsidence of the ingrowth prosthesis, which later stabilized and proved to be insignificant. Ectopic bone formed on the posterior femoral neck of all the ingrowth hips. Sclerotic lines were observed in four of these patients but showed no correlation to the physical ability of the patients. Therefore, the ingrowth or uncemented hip arthroplasty appears to be functionally equivalent to the cemented hip arthroplasty and more symptomatic.

Total hip replacement comparison between the McKee-Farrar and Charnley prostheses in a 5-year follow-up study.

Abstract: In a prospective study, 177 patients who underwent total hip replacement by the McKee-Farrar or Charnley techniques were followed up for 5 years with yearly clinical examinations, walking tests, and X-rays. The findings concerning pain, walking ability, and complications were satisfactory and similar to the inventors' own 5-year results. Comparison between the two techniques disclosed no major differences. Over 90% of the patients were free from pain; the infection rate was 3.4% and the loosening rate 6%. A walking test showed marked increase in speed over the first few years and a slight decrease after the third year. Our findings do not support the hypothesis that the metal-on-metal prosthesis is clinically inferior to the metal-on-polyethylene prosthesis.