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PubMed1995

[Primary total endoprosthetic hip joint replacement in acetabulum fractures].

Conservative treatment of acetabular fractures mean a long period with immobilisation followed by quite a few of complications that are life-threatening to old patients. Besides that these fractures often cause painful posttraumatic osteoarthritis of the hip joint. Open reduction and osteosynthesis is favored more and more, but the complications described cannot be avoided absolutely by surgical treatment. The sequelae are risky reoperations and the necessity for implantation of total joint prosthesis. As shown in the enclosed case reports, total hip replacement can be emphasized as first step and as definitive surgery. Implantation of an artificial joint allows postoperative remobilisation with full weight bearing and long lasting immobilisation can be avoided. Therefore this kind of therapy is justified for treatment of old and polymorbid patients as an out of rule therapy.

Acetabulum↗
PubMed1991

Tribology of human and artificial joints.

Studies of human joint lubrication mechanisms have led to the conclusion that under normal healthy conditions they are fluid film lubricated. The main features responsible for allowing this mechanism to operate are the dynamic nature of the loading and the compliance of the bearing surfaces (articular cartilage). In contrast, artificial joints, being made of much more rigid materials, have been demonstrated to be lubricated by a mixed regime, where some load is carried by the fluid film and some by solid to solid contact. Since some surface contact takes place then wear remains a problem and friction is much higher than in human joints. The use of compliant surface bearings for artificial joints has been explored and shown to be of great advantage, reproducing the effects of natural joints. However, elastomeric materials are known to degrade in aqueous solutions so this aspect has been examined to ensure a reasonable life in the human body. Joints of the lower limb--hip, knee, and ankle--have similar load and motion patterns and behave in a similar way in terms of lubrication. Joints of the hand are not in any way similar in their behaviour and so a typical upper limb joint, the finger, has been studied to see if improvements can be made to the design of replacement artificial joints. Novel suggestions like plastic on plastic joints have been shown to be an alternative which is worthy of further consideration.

Cartilage, Articular↗
PubMed2006

Continuous monitoring of the performance of hip prostheses.

New brands of joint prosthesis are released for general implantation with limited evidence of their long-term performance in patients. The CUSUM continuous monitoring method is a statistical testing procedure which could be used to provide prospective evaluation of brands as soon as implantation in patients begins and give early warning of poor performance. We describe the CUSUM and illustrate the potential value of this monitoring tool by applying it retrospectively to the 3M Capital Hip experience. The results show that if the clinical data and methodology had been available, the CUSUM would have given an alert to the underperformance of this prosthesis almost four years before the issue of a Hazard Notice by the Medical Devices Agency. This indicates that the CUSUM can be a valuable tool in monitoring joint prostheses, subject to timely and complete collection of data. Regional or national joint registries provide an opportunity for future centralised, continuous monitoring of all hip and knee prostheses using these techniques.

Adult↗
PubMed2005

Patients with artificial joints: do they need antibiotic cover for dental treatment?

This study reviews whether patients with artificial joints need antibiotic cover for dental treatment. Generally in Australia the practice has developed of giving most patients with artificial joints antibiotic prophylaxis for a wide range of dental procedures. This is partly on anecdotal grounds, partly historical and partly for legal concerns. It has been encouraged by some guidelines. Scientifically, the risk and the benefit of each step in the process needs to be analysed. This review shows that the risk of an artificial joint becoming infected from a bacteraemia of oral origin is exceedingly low whereas the risk of an adverse reaction to the antibiotic prophylaxis is higher than the risk of infection. If all patients with artificial joints receive antibiotic prophylaxis then more will die from anaphylaxis than develop infections. Factors which balance the risk benefit are if the patient is seriously immunocompromised, if the joint prosthesis is failing or chronically inflamed and if the dental procedures, such as from extractions and deep periodontal scaling, produce high level bacteraemias. Recommendations to rationalize antibiotic prophylaxis for patients with artificial joints are presented.

Antibiotic Prophylaxis↗
PubMed2002

Knee joint aspiration and injection.

Knee joint aspiration and injection are performed to aid in diagnosis and treatment of knee joint diseases. The knee joint is the most common and the easiest joint for the physician to aspirate. One approach involves insertion of a needle 1 cm above and 1 cm lateral to the superior lateral aspect of the patella at a 45-degree angle. Once the needle has been inserted 1 to 1 1/2 inches, aspiration aided by local compression is performed. Local corticosteroid injections can provide significant relief and often ameliorate acute exacerbations of knee osteoarthritis associated with significant effusions. Among the indications for arthrocentesis are crystal-induced arthropathy, hemarthrosis, unexplained joint effusion, and symptomatic relief of a large effusion. Contraindications include bacteremia, inaccessible joints, joint prosthesis, and overlying infection in the soft tissue. Large effusions can recur and may require repeat aspiration. Anti-inflammatory medications may prove beneficial in reducing joint inflammation and fluid accumulations.

Humans↗
PubMed2006

Meniscal wear at a three-component total ankle prosthesis by a knee joint simulator.

Despite the fundamental value of wear simulation studies to assess wear resistance of total joint replacements, neither specialised simulators nor established external conditions are available for the human ankle joint. The aim of the present study was to verify the suitability of a knee wear simulator to assess wear rates in ankle prostheses, and to report preliminary this rate for a novel three-component total ankle replacement design. Four intact 'small' size specimens of the Box ankle were analysed in a four-station knee wear simulator. Special component-to-actuator holders were manufactured and starting spatial alignment of the three-components was sought. Consistent load and motion cycles representing conditions at the ankle joint replaced exactly with the prosthesis design under analysis were taken from a corresponding mechanical model of the stance phase of walking. The weight loss for the three specimens, after two million cycles, was 32.68, 14.78, and 62.28mg which correspond to a linear penetration of 0.018, 0.008, and 0.034mm per million-cycle, respectively for the specimens #1, #2, and #3. The knee wear simulator was able to reproduce load-motion patterns typical of a replaced ankle. Motion of the meniscal bearing in between the tibial and talar components was smooth, this component remaining in place and in complete congruence with the metal components throughout the test.

Ankle Joint↗
PubMed2003

Socioeconomic impact of osteoarthritis in Hong Kong: utilization of health and social services, and direct and indirect costs.

OBJECTIVE: To determine the direct and indirect cost of osteoarthritis (OA) according to disease severity, and to estimate the total cost of the disease in Hong Kong. METHODS: This study is a retrospective, cross-sectional, nonrandom, cohort design, with subjects stratified according to disease severity based on functional limitation and the presence or absence of joint prosthesis. Subjects were recruited from primary care, geriatric medicine, rheumatology, and orthopedic clinics. There were 219 patients in the mild disease category, 290 patients in the severe category, and 65 patients with joint replacement. A questionnaire gathered information on demographic and socioeconomic characteristics, function limitation, use of health and social services, and effect on occupation and living arrangements over the previous 12 months. Costs were calculated as direct and indirect. RESULTS: Low education and socioeconomic class were associated with more severe disease. OA affected family or close relationships in 44%. The average cost incurred as a result of side effects of medication is similar to the average cost of medication itself. Excluding joint replacement, the direct costs ranged from Hong Kong (HK) dollar $11,690 to $40,180 per person per year and indirect costs, HK $3,300-$6,640. The direct costs are comparable to those reported in Western countries; however, the ratio of direct to indirect costs is much higher than 1, in contrast to the greater indirect versus direct costs reported in whites. The total cost expressed as a percentage of gross national product is also much lower in Hong Kong. CONCLUSIONS: The socioeconomic impact of OA in the Hong Kong population is comparable to Western countries, but the economic burden is largely placed on the government, with patients having relatively low out-of-pocket expenditures.

Costs and Cost Analysis↗
PubMed1976

The locomotion laboratory as a clinical assessment system.

As a routine clinical tool the locomotion laboratory has been a long time evolving. This paper reviews the development, successes and failures of locomotion assessment systems. A detailed picture of the state of knowledge of normal gait is presented along with some suggested directions regarding needed technological development as well as some criticism of the lack of biomechanical modelling. As examples of clinical applications, four major gait pathologies are reviewed: amputees, hemiplegia, cerebral palsy and joint replacement. The state of knowledge of each of these patient populations is presented along with a critique of the assessment methods and conclusions. It is hoped that this paper will provoke discussion regarding the real purpose of a clinical locomotion laboratory, and put some perspective on the cost in terms of equipment, space, newly trained or retrained personnnel and computer systems.

Amputees↗
PubMed1998

Immunohistochemical analysis of matrix proteolytic enzymes in the periprosthetic tissue in the patients with loosening prostheses.

Regional periprosthetic bone resorption plays an important role of prosthesis loosening. In order to study the possible mechanisms of loosening, we investigated the presence of matrix proteolytic enzymes in the periprosthetic tissue by immunohistochemical technique in 72 patients undergoing revision operation of loosened joint prosthesis, including 22 males and 50 females and aged from 19 to 88 years (mean, 61.7 years). Thirty-nine patients had a loosened hip prosthesis (18 males and 21 females) whereas 33 patients had a loosened knee prosthesis (4 males and 29 females). Tissue specimens collected during revision surgery underwent thin slide sections and H & E staining, and were observed under light microscopy and polarized-light microscopy. The results showed many macrophages, histiocytes, fibroblasts, as well as many phagocytosed metal debris and polyethylene debris in the periprosthetic tissues, suggesting an active bone resorption. Furthermore, we used immunohistochemical techniques to detect the distribution of matrix proteolytic enzymes in periprosthetic tissue, including lysosome enzymes (cathepsin B, cathepsin D and cathepsin G), and matrix metalloproteinase (MMPs, MMP-1, MMP-2, MMP-3). The immunostaining were classified as strong positivity, > 70% positive cells; moderate positivity, 20-70% positive cells; weak/negative, < 20% positive cells. The results showed that cathepsin B, cathepsin D and cathepsin G were found in most fibroblasts and macrophage-like cells, including multinuclear giant cells and epithelioid cells. MMPs were found in most fibroblasts and macrophage-like cells, as well as a scant amount in the extracellular matrix. These enzymes were also found in or around blood vessels, the endothelial cells in the richly vascularized tissue. All negative controls showed no staining. The results of immunoreactive staining ranged from 61.1% to 68.1% of strong to moderate positivity. Since these enzymes were related to the degradation of matrix protein, they may be related to the periprosthetic bone resorption. The further clinical significance needs further investigation.

Adult↗
PubMed2006

Hip prosthesis infection due to Mycobacterium wolinskyi.

Mycobacterium wolinskyi, first described in 1999, is a rapidly growing mycobacterium related to the Mycobacterium smegmatis group. Only eight cases of infection due to this microorganism have been reported, including three cases of bone infection. Here, we present the first case of a joint prosthesis infection cured with the combination of surgery and prolonged antibiotic therapy. The microorganism was identified by biochemical tests and 16S rRNA and Hsp65 gene sequence analysis.

Aged, 80 and over↗
PubMed2006

Assessments of different kinds of stems by experiments and FEM analysis: appropriate stress distribution on a hip prosthesis.

BACKGROUND: It is now recognized that initial stability is essential for avoidance of thigh pain in hip replacement. The initial stability corresponds to an optimal stress distribution of cementless orthopedic implants. Although the relationship between the contour and stress at the fixation site has been analyzed, guidelines on stem design have not been established. METHODS: Finite element models of three currently-used stems were constructed for a computer simulation. Contact stress at the fixation site of a joint prosthesis was analyzed by an explicit three-dimensional finite element method. The stress immediately after applying load using a film or sensor which can measure contact stress was observed. The situation of the initial fixation about the specific part which becomes important clinically based on the results was clarified. FINDINGS: We introduced fluctuation area as a measure to evaluate the primary fixation of femoral stems. It was found that the stress distribution on the PerFix SV stem fluctuated with a slight disturbance. On the Intra-Medullary Cruciate stem, the high stress areas were distributed on the proximal area and under the pin. The high stress area on the VerSys stem were spread on the medial side. INTERPRETATION: This study highlights the mechanical instability of the fixation site of joint prostheses, and thus suggests that the general idea that unconditionally recommends a larger area for the fixation site of joint prostheses should be revised.

Biomechanical Phenomena↗
PubMedDate not supplied

[In vivo measurement of hip joint stress. 1. Physical therapy].

The forces acting during physiotherapy in both hip joints of one patient have been measured in vivo using a telemeterized joint prosthesis. During supported exercises the loads are up to 50% of the body weight (BW). Active movement of the leg against resistance in a lying position let the forces rise up to 250% BW. During symmetric two-legged-stance the load is typically 70% BW, while during walking peak values of about 300% BW were measured. By use of one crutch a 25% reduction of the joint force can be achieved.

Biomechanical Phenomena↗