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The case of a 50-year-old man is presented who underwent reoperation for a malfunctioning Björk-Shiley spherical valve which had been inserted 14 years previously. The patient made a satisfactory recovery after surgery. Examination of the explanted valve revealed that a segment of the pyrolytic carbon disc was missing. There was no evidence of embolization.
This report presents a case of severe dysfunction of an improved Model 104 Beall valve secondary to disc wear. This type of valve failure may be extremely difficult to detect by auscultation, echocardiography, or fluoroscopic examination. Prosthesis failure with resulting mitral insufficiency should be considered in any patient with a Teflon disc Beall mitral valve in whom there is unexplained clinical deterioration.
In vitro cellular immune responses to metallic and polymeric implant materials in particulate form were measured preoperatively in 185 patients. The patients were candidates for either primary total joint replacement (n = 65) or revision arthroplasty (n = 120). Proliferative cellular responses to polymethylmethacrylate particles in patients with osteoarthritis at revision surgery for aseptic loosening were significantly higher than the responses of patients with osteoarthritis at either primary surgery or surgical revision for mechanical failure of the prosthesis or sepsis. The responses to particles of cobalt-chromium alloy at revision surgery were also higher than the responses at primary surgery. The responses were reevaluated in 32 patients after a minimum of 10 months following surgery to correlate individual changes in the biological responses with clinical progress. Reevaluation at early follow-up of patients who had undergone primary surgery revealed significantly elevated proliferative responses and in vitro cytokine production in response to polymethylmethacrylate and cobalt-chromium alloy particles compared with their preoperative responses. In contrast, the response at follow-up to polymethylmethacrylate was significantly reduced in patients who had undergone revision surgery, and this reduction corresponded with a marked improvement in pain, joint motion, and function following revision surgery. These data suggest that specific cellular responses to polymethylmethacrylate or cobalt-chromium alloy particles, or both, may be associated with loose or painful prostheses.
BACKGROUND: The aim of the study was to evaluate the late results of the Carpentier-Edwards pericardial bioprosthesis, which we have been implanting since 1981. METHODS: The 812 patients who underwent heart valve replacement with a Carpentier-Edwards pericardial bioprosthesis between 1981 and 1996 were reviewed. Their clinical, operative, and follow-up data were prospectively recorded in a computerized database. All but 29 patients were available for follow-up (96% completeness), which averaged 58 months and totaled 3,000 patient-years. RESULTS: There were 598 aortic valve replacements (74%), 149 mitral valve replacements (18%), and 65 double valve replacements (8%). The mean age at the time of surgery was 65 years (range, 18 to 88 years), with 24% of the patients under the age of 60 years. Preoperatively, 558 patients (69%) were in New York Heart Association functional class III or IV. Associated surgical procedures included coronary artery bypass grafting in 219 patients (27%) and tricuspid or mitral valve repair in 40 (5%). Previous cardiac operations had been performed in 149 patients, including 134 valve-related procedures. There were 49 early deaths overall (6%): 29 after aortic valve replacement (4.8%), 11 after mitral valve replacement (7.4%), and 9 with double valve replacement (13.8%). There were 120 late deaths for a 10-year actuarial survival rates of 69%+/-3%, 58%+/-7%, and 38%+/-10% for aortic, mitral, and double valve replacement, respectively. The 14-year survival rate for aortic valve replacement patients is 68%+/-3%. The 10-year and 14-year actuarial freedom rates from events after aortic valve replacement are 92% +/-2% and 88%+/-4% for thromboembolism, 96%+/-1% and 92%+/-4 for endocarditis, 91%+/-2 and 72%+/-6% for reoperation, and 93%+/-2% and 80%+/-5% for structural dysfunction of the valve. The 10-year actuarial freedom rates from events after mitral and double valve replacement are 93%+/-3% and 89%+/-4% for thromboembolism, 95%+/-3% and 88%+/-5% for endocarditis, 76%+/-7% and 70%+/-14% for reoperation, and 81%+/-7% and 72%+/-15% for structural dysfunction. No primary tissue failure of the prosthesis in any position was observed in the 357 patients aged 70 years or more at the time of valve implantation. CONCLUSIONS: The Carpentier-Edwards pericardial valve offers excellent clinical results and durability, particularly in the aortic position and for patients older than 70 years of age.
Many materials are used as artificial joint bearing surfaces; these include conventional stainless steel or CoCrMo-on-ultra-high molecular weight polyethylene (UHMWPE), CoCrMo on itself and alumina-on-alumina. However, these joints have a limited lifespan resulting in failure of the prosthesis and the need for revision surgery. A number of materials have been introduced recently in an attempt to overcome these problems. Polycarbonate urethane (PU) is a compliant material that can be used as an artificial joint bearing surface which has been developed to mimic the natural synovial joint more accurately by promoting fluid film lubrication. Tribological tests were performed on CoCrMo-on-PU unicondylar knee prostheses to assess their performance in vitro. The wear produced by these components was considerably lower than that found for conventional joints. They also exhibited low friction and operated close to full-fluid film lubrication with viscosities of lubricant similar to those found in patients with arthritis. These tests gave encouraging results for the tribological performance of this material couple for use as an alternative bearing combination.
STUDY DESIGN: This study analyzed retrospectively 46 patients undergoing artificial disc replacement. OBJECTIVE: To assess the clinical and radiographic outcomes of patients who had Charitè SB III disc prosthesis. SUMMARY OF BACKGROUND DATA: Results of disc prosthesis have been reported only at very short-term follow-up periods; preoperative diagnosis and criteria used to evaluate the clinical outcomes were not reported. METHODS: Forty-six patients who had had a disc prosthesis were evaluated clinically and radiographically at least 2 years after surgery. Preoperative diagnosis included disc degeneration in 22 patients and failed disc excision in 24 patients. Disc prosthesis was implanted at a single vertebral level in 36 patients and at two levels in 10 patients. Follow-up evaluation was performed after an average of 3.2 years (range, 2-5 years). RESULTS: Sixty-three percent of patients reported satisfactory results. The success rate was 69% in patients who underwent isolated disc replacement and 77% in those with no previous back surgeries. Seven patients who had unsatisfactory results underwent posterolateral fusion without removing the artificial disc. Two patients underwent removal of the prosthesis. No failure of the implants or loosenings or wear of the polyethylene core were found. Vertebral motion averaged 9 degrees at the operated levels and 16 degrees at the adjacent levels. CONCLUSION: A wrong surgical indication, rather than failure of the prosthesis, appears to be the main cause of unsatisfactory results of disc replacement at medium-term evaluations. Prospective and longer term studies are needed to establish whether disc prosthesis may offer advantages compared with spinal fusion.
Although valve replacement remains the cornerstone of treatment for critical heart valve dysfunction, problems including thromboembolism, infection, and primary failure of the prosthesis remain. Resting studies of valve hemodynamics are sometimes insufficient to reveal valve dysfunction. Early studies using cardiac catheterization focused on changes in prosthetic function seen with various types of exercise or drug-induced stress. These studies suffered from an inability to adequately stress catheterized patients and were cumbersome to the patient and the investigator. With the introduction of Doppler echocardiography, however, studies could be performed after significant exercise with low risk and increased ease. Using echocardiography, reports of exercise-induced changes in aortic and mitral valve hemodynamics have appeared. Over 600 patients have been studied using Doppler echocardiography. In the aortic position, all prostheses studied have a mild peak instantaneous gradient (18-26 mmHg) at rest, which increases with exercise (35-63 mmHg). No significant differences between the four models of mechanical prostheses studied are found. The gradients achieved with exercise do not appear to be related to the heart rate achieved or duration of exercise. Smaller prostheses are associated with larger gradients; however, the correlation was not strong. All mitral valve prostheses studied are also mildly stenotic at rest (range of mean gradients 2.3-7.1 mmHg) and become moderately stenotic with exercise (range 5.1-16.5). Although the lowest gradients are seen with St. Jude Medical and Medtronic Hall prostheses, their gradients are not significantly less than with other valves.(ABSTRACT TRUNCATED AT 250 WORDS)
Sixty-four Indiana conservative (Depuy, Warsaw, IN) hip arthroplasties performed in 61 patients were reviewed for loosening, mechanisms of loosening, and revision rate. Mean follow-up time was 6.8 years. There were revisions in 26 hips (40.6%) with 4 hips awaiting revision, yielding a total of 30 hips (47%) defined as failures. Acetabular failure occurred in 20 hips, femoral failure in 18, and combined failure in 13. Failure of this prosthesis persists over time. There seems to be little or no place for this design in contemporary hip joint arthroplasty.
Survivorship analysis, which is often encountered in the medical literature, is used to calculate the probability of a certain event, such as failure of a prosthesis, as a function of the time elapsed since an operation. Possible pitfalls in the use of this method are related to the size of the population of patients and the definition of how the outcome is measured. We studied the outcomes of 204 total knee arthroplasties in 165 patients, using six different end-points, in order to illustrate these problems. Survivorship estimates that are cited without confidence intervals have little clinical value.
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We studied retrospectively and prospectively 34 cases of failed knee arthroplasty. The failure was mostly due to contralateral progressive arthrosis in the tibiofemoral joint (15 cases, 44.1%). Instabilization of the knee joint and abnormal ranked prosthesis second (9 cases, 26.5%), and loosening third (7 cases, 20.6%). Infections were noted only in 3 cases (8.8%). This prosthesis demands meticulous surgical techniques and strict indications because of its geometric characteristics and stabilization. Contralateral progressive arthrosis and abnormal prosthesis accounted for 70.0% in all, and were resulted from poor surgical technique and improper indications.
Failure of the mechanical parts in a valve prosthesis is a rare, but life-threatening complication. The incidence depends on the type of valve. We present a case of outflow strut fracture of a Björk-Shiley 70 degrees convexo-concave mitral valve prosthesis, and discuss diagnosis and treatment.
A retrospective study was done on a consecutive series of patients who had revision of a femoral hip prosthesis using a titanium-alloy implant with proximal fibermesh pads. Of 28 patients who had revision using a Harris-Galante (Zimmer, Warsaw, IN) femoral prosthesis between 1985 and 1989, 25 of them (25 hip arthroplasties) were followed for an average of 5.5 years (range, 4-8 years); the other 3 had died. There were 12 men and 13 women whose age averaged 55 years. Thirty-two percent of the patients had moderate or severe femoral bone stock deficiency before surgery and 72% had intramedullary femoral bone-grafting. All of the patients had revision of the acetabular component using a cementless Harris-Galante prosthesis. Five (20%) of the 25 patients have undergone repeat femoral revision, 4 for aseptic loosening and 1 for persistent thigh pain. Of the 20 hips that have not been revised, 9 (45%) of the femoral prostheses have subsided 5 mm or more. Femoral endosteal lysis was present in 36% of all the hips. Only 8 (32%) of the 25 patients had radiologic signs of bone ingrowth fixation of the femoral component. The average Harris hip score rose from 46 before surgery for all 25 patients to 82 (range, 55-100) at last follow-up examination for the 20 patients not rerevised. Because of the poor clinical results (36% of patients with a poor Harris hip score [4 patients] or rerevised [5 patients]) and radiologic results (48% subsidence) of femoral reconstruction with this proximally porous-coated femoral prosthesis, its use for revision hip surgery is not recommended.
UNLABELLED: New prostheses should be evaluated for stability and clinical performance. In a prospective randomized clinical trial, we implanted 22 titanium (Ti) and 20 hydroxyapatite-coated (HA) ProxiLock femoral hip prostheses during total hip arthroplasty in 42 patients. The patients were followed for 24 months with clinical, radiographic and radiostereometric analysis. Full weightbearing was allowed immediately postoperatively. One patient with a titanium stem was lost to followup. During the first two months, 34 of the 41 stems subsided and/or rotated towards retroversion, regardless of stem type. At the 24-month followup 35 of the 41 prostheses were either fully stabilized (16 HA and 11 Ti stems) or had clinical irrelevant migration (four HA and four Ti stems). Six Ti prostheses showed continuous migrations with maximums of 4.7 mm translation and 12.2 degrees retroversion; four of these were revised, the other two had no clinical complaints. CLINICAL RELEVANCE: The migration pattern we found indicates insufficient primary fixation of the ProxiLock stem in an immediate full weightbearing protocol. The HA coating improves the secondary stability of the prosthesis compared to the uncoated stem. Early migration is associated with an increased risk of possible future loosening and revision, and therefore we discontinued the use of this prosthesis. LEVEL OF EVIDENCE: Therapeutic Level I. See Guidelines for Authors for a complete description of levels of evidence.
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Forty revisions for failure of unicompartmental knee prostheses were assessed. Twenty-eight women and twelve men (mean age: 67 years) were reoperated. Failure of an medial single-compartment prosthesis was involved in 35 cases, of a lateral prosthesis in 5 cases. The initial prostheses had been cemented in 19 cases and uncemented in 21 cases. Preoperative functional conditions were assessed by Hungerford's functional score and a 200-points score. The radiological study before revision showed 35 cases of varus distortion; in 12 of these, the varus distortion exceeded 10 degrees. Rather than studying the causes for failure of the single-compartment prosthesis, it seemed more useful to try to define the adequate reoperation procedure strategy and analyze its results. Our procedure aimed at solving the following difficulties: surgical approach: the same incision as in the initial operation was performed, the primary prosthesis was removed and a two-stage treatment was justified in cases of infection, metallosis involved complete removal of debris, the problem of bone-recutting and, chiefly, the problem of residual bone defect requiring bone-graft. Bone-recutting was performed with the tibial and femoral elements of the primary prosthesis still in place and using the ancillary equipment of the new prosthesis. Bone defects involved the femur as often (14 cases) as the tibia (12 cases); tibial bone defects occurred more frequently with cemented prostheses (9 cases) than with uncemented prostheses (3 cases). Femoral graft being relatively easier to perform one of the two major difficulties in our strategy was the achievement of a tibial graft.(ABSTRACT TRUNCATED AT 250 WORDS)