Arthroplasty of the hip.
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Arthroplasty, Replacement, Hip↗
Biomedical subjects
R A Elson
Publications and source records attributed to R A Elson.
Precision of EBRA-Digital software for monitoring implant migration after total hip arthroplasty.
We assessed the precision of the EBRA-Digital software (EBRA, University of Innsbruck, Innsbruck, Austria) for measuring implant migration after total hip arthroplasty. Study subjects (n = 29) underwent consecutive, standardized, plain radiographic examinations of the hip on the same day after repositioning. The resulting radiograph pairs were digitized and analyzed using EBRA. The precision (95% confidence interval) of the method for measuring migration and wear was <+/-0.9 mm for both implant components. The 95% confidence intervals for measurement of cup inclination and anteversion and femoral stem/shaft angle were <+/-1.7 degrees. Measurement precision was not strongly related to patient gender, digitization method, or observer. The EBRA-Digital method has sufficient precision to detect clinically relevant migration to allow individual patient monitoring after total hip arthroplasty. The method requires careful patient positioning and radiographic technique to produce consistently images suitable for analysis.
Arthroplasty, Replacement, Hip↗
Measuring bone mineral density of the pelvis and proximal femur after total hip arthroplasty.
We aimed to evaluate the precision and longitudinal sensitivity of measurement of bone mineral density (BMD) in the pelvis and to determine the effect of bone cement on the measurement of BMD in femoral regions of interest (ROI) after total hip arthroplasty (THA). A series of 29 patients had duplicate dual-energy x-ray absorptiometry (DXA) scans of the hip within 13 months of THA. Pelvic analyses using 3- and 4-ROI models gave a coefficient of variation (CV) of 2.5% to 3.6% and of 2.5% to 4.8%, respectively. Repeat scans in 17 subjects one year later showed a significant change in BMD in three regions using the 4-ROI model, compared with change in only one region with the 3-ROI model (p < 0.05). Manual exclusion of cement from femoral ROIs increased the net CV from 1.6% to 3.6% (p = 0.001), and decreased the measured BMD by 20% (t = 12.1, p < 0.001). Studies of two cement phantoms in vitro showed a small downward drift in bone cement BMD giving a measurement error of less than 0.03 g/cm2/year associated with inclusion of cement in femoral ROIs. Changes in pelvic periprosthetic BMD are best detected using a 4-ROI model. Analysis of femoral ROI is more precise without exclusion of cement although an awareness of its effect on the measurement of the BMD is needed.
Adult↗
Effect of pamidronate in preventing local bone loss after total hip arthroplasty: a randomized, double-blind, controlled trial.
Acute periprosthetic bone loss occurs after total hip arthroplasty. Bone loss undermines the support of the implant and may contribute to prosthetic failure. At present, there is no established prophylaxis for this process. We studied the effect of a single-dose infusion of 90 mg of pamidronate on early periprosthetic bone mineral density (BMD), biochemical markers of bone turnover, radiological, and clinical outcome in a 26-week, prospective, randomized, double-blinded study of 47 men and women undergoing total hip arthroplasty. Pamidronate therapy led to a significant reduction in bone loss compared with placebo for both the proximal femur and the pelvis (repeated measures analysis of variance [ANOVA]); p = 0.001 and p = 0.01, respectively). Pamidronate therapy was associated with suppression of all biochemical markers of bone turnover compared with placebo (repeated measures ANOVA; p < 0.05 for all comparisons), with the exception of urinary free deoxypyridinoline. Pamidronate did not interfere with the clinical improvement in symptoms after total hip arthroplasty, or radiological outcome, and was not associated with an increase in adverse events. This study provides clinical data on the efficacy and safety of bisphosphonates for the prevention of bone loss after total hip arthroplasty and supports the establishment of larger-scale clinical trials to determine the long-term clinical efficacy of this intervention using implant failure as the primary endpoint.
Aged↗
Changes in allograft bone irradiated at different temperatures.
Secondary sterilisation of allograft bone by gamma irradiation is common, but the conditions under which it is performed vary between tissue banks. Some do so at room temperature, others while the bone is frozen. Bone is made brittle by irradiation because of the destruction of collagen alpha chains, probably mediated by free radicals generated from water molecules. Freezing reduces the mobility of water molecules and may therefore decrease the production of free radicals. We found that bone irradiated at -78 degrees C was less brittle and had less collagen damage than when irradiated at room temperature. These findings may have implications for bone-banking.
Adult↗
Surgical management of fractures of the acetabulum: the Sheffield experience 1976-1994.
Of 56 acetabular fractures treated in Sheffield between 1976 and 1994, 43 fractures in 40 patients underwent open reduction and internal fixation. This paper reviews the surgically managed fractures with emphasis on the quality of operative reduction and outcome, in particular the development of degenerative osteoarthritis leading to total hip replacement. A good clinical result following operative management was seen to correlate closely with a near perfect reduction; in contrast, all cases with a poor reduction underwent joint replacement in the follow-up period. The relatively few cases managed at a major referral centre in this series suggest that either the incidence of acetabular fracture is low in the area or that only a proportion of cases are referred from the surrounding district general hospitals.
Acetabulum↗
Biochemical properties of cortical allograft bone using a new method of bone strength measurement. A comparison of fresh, fresh-frozen and irradiated bone.
There have been conflicting reports on the effects of gamma irradiation on the material properties of cortical allograft bone. To investigate changes which result from the method of preparation, test samples must be produced with similar mechanical properties to minimise variations other than those resulting from treatment. We describe a new method for the comparative measurement of bone strength using standard bone samples. We used 233 samples from six cadavers to study the effects of irradiation at a standard dose (28 kGy) alone and combined with deep freezing. We also investigated the effects of varying the dose from 6.8 to 60 kGy (n = 132). None of the treatments had any effect on the elastic behaviour of the samples, but there was a reduction in strength to 64% of control values (p < 0.01) after irradiation with 28 kGy. There was also a dose-dependent reduction in strength and in the ability of the samples to absorb work before failure. We suggest that irradiation may cause an alteration in the bone matrix of allograft bone, but provided it is used in situations in which loading is within its elastic region, then failure should not occur.
Adolescent↗
Skin closure using nylon and polydioxanone: a comparison of results.
Nylon vertical mattress sutures and interrupted subcuticular polydioxanone (PDS) sutures have been used for skin closure. The complications and cosmetic results of each have been noted in a prospective trial of 93 hip wounds. When nylon sutures are used there is an increased incidence of erythema and the final scar is less cosmetically attractive. Interrupted PDS sutures take longer to insert but have few complications and are recommended in both the young and elderly patients.
Adult↗
Exchange arthroplasty for infection. Perspectives from the United Kingdom.
A number of factors are considered with a bearing on outcome assessment and survivorship analysis. The results achieved in more than 440 exchange arthroplasties are discussed. Despite the apparent threefold increased risk of recurred infection associated with a one-stage approach, this statistic is an oversimplification of the many complex factors involved in the analysis of these results and in the decision between a one- and a two-stage approach to treatment, when presented with an infected hip replacement. The authors think that a one-stage approach remains a reasonable alternative, given certain prerequisites.
Anti-Bacterial Agents↗
The saddle prosthesis for salvage of the destroyed acetabulum.
We report the 12 to 74 month results of our mark I saddle prosthesis after its use as a salvage device for gross loss of pelvic bone stock in 76 patients with failed hip arthroplasties. The implant transmits load between iliac bone and bare polish chrome-cobalt. Our clinical and radiological results indicate that a useful and stable articulation can be achieved in most cases, provided that continued deep infection can be avoided. The appearance of radiological sclerosis at the bearing site in successful cases seems to indicate that significant late migration will not occur. Based on our experience with the mark I prosthesis we have designed and developed a mark II model which has freedom of axial rotation of the saddle. Our early results in 40 cases show a significant improvement over the results which could have been predicted for the mark I device.
Acetabulum↗
Bicondylar St. Georg sledge knee arthroplasty.
Fifty-three bicondylar St. Georg sledge knee arthroplasties in 44 patients were reviewed. These patients had a mean follow-up period of 5.9 years (range, three to ten years). Function was assessed using the d'Aubigné scale coupled with measurement of range of motion (ROM) and stability. Pain relief was substantial (75%), and functional ability improved commensurately. ROM improved from a preoperative average of 83 to a postoperative 123. Three (5.7%) arthroplasties failed and were subsequently revised, while three (6.8%) of the knees examined at review have static radiolucent lines at the tibial bone-cement interface. The remaining 44 knees examined (93.2%) showed no signs of impending failure and have sustained their functional result. The polyethylene tibial components are not metal backed, and it is of interest that bone-cement interface failure has been unusual. This operation is a somewhat exacting procedure, but with the correct choice of patient and technique, a predictable result can be expected.
Adult↗
Embolisation for aneurysm after knee replacement: brief report.
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Aneurysm↗
Deep infection of cemented total hip arthroplasties caused by coagulase-negative staphylococci.
We reviewed a series of 91 patients with deep infection of a cemented total hip arthroplasty caused by coagulase-negative staphylococci (C-NS). Of these, 72 were treated by one-stage exchange arthroplasty with a failure rate of 13% due to recurrence of infection. The other 19 patients have started or completed treatment by a two-stage exchange without failure to date. In 27 of the 91 patients multiple strains of C-NS were discovered, many being resistant to previously used antibiotics. The use of gentamicin-containing cement in the primary arthroplasty was significantly associated with the emergence of gentamicin-resistant C-NS in subsequent deep infection. Bacteriological diagnosis of such infections must take into consideration the possibility that multiple strains of the organism are involved.
Anti-Bacterial Agents↗
Ultraclean air and antibiotics for prevention of postoperative infection. A multicenter study of 8,052 joint replacement operations.
To determine the value of ultraclean air in operating rooms, 8,052 operations for total hip- or knee-joint replacement were followed up for 1-4 years. For operations done in ultraclean air, bacterial contamination of the wound, deep joint sepsis, and major wound sepsis were substantially less than for operations done in conventionally ventilated rooms. Sepsis was also less frequent when prophylactic antibiotics had been given. The two precautions acted independently so that the incidence of sepsis after operation in ultraclean air and with antibiotics was much less than that when either was used alone. Wound sepsis was associated with an enhanced risk of joint sepsis. Staphylococcus aureus was the commonest joint pathogen, but infections with other organisms, often considered to be of low pathogenicity, were almost as numerous. Most S. aureus infections were traced to sources in the operating room.
Air Microbiology↗
Skin closure using staples and nylon sutures: a comparison of results.
A disposable skin stapler (Elite: Auto Suture UK Ltd) and Nylon vertical mattress sutures have been used for skin closure. The complications related to each method were evaluated in 129 wounds. There was a higher incidence of inflammation, discomfort on removal and spreading of the healing scar associated with staples. The only advantage of staples was speed of wound closure.
Arthroplasty↗
Rupture of the central slip of the extensor hood of the finger. A test for early diagnosis.
Closed rupture of the middle slip of the extensor hood of a finger is easily missed until the late appearance of a buttonhole deformity. Early diagnosis gives the best chance of satisfactory treatment, but Boyes' test becomes positive only at a late stage. A new test is described in which, from a 90 degree flexed position over the edge of a table, the patient tries to extend the proximal interphalangeal joint of the involved finger against resistance. The absence of extension force at the proximal joint and fixed extension at the distal joint are immediate signs of complete rupture of the central slip. The theoretical basis and the method of performing the test are discussed.
Finger Injuries↗
Antibiotic-loaded acrylic cement: current concepts.
Antibiotic-loaded acrylic cement has been used routinely since 1972 at the authors' hospitals, where a series of some 22,000 joint arthroplasty operations was performed from 1964-1983. The current status of the material is presented with up-to-date follow-up statistics on prophylactic therapy and on established deep infections. The results of 869 exchange arthroplasties are compared with results published in 1981. In the future, results will be presented in the form of survival curves. The method by which survival tables and curves are constructed is critical. Investigators should use survival curves for ease of comparison and because of the wide range of possibilities in an analysis of covariable factors. A retrospective actuarial analysis was made of 825 one-stage reimplantations in which antibiotic-loaded acrylic cement was used for infected total hip arthroplasties. Staphylococcus aureus was the most commonly encountered organism. Failure rates of prostheses infected by S. aureus, S. species, and anaerobic corynebacteria did not differ statistically. A factor that significantly contributed to failure of this method of treatment was Pseudomonas infection. By actuarial analysis five years after operation, a success (survival) rate of 77% was calculated.
Anti-Bacterial Agents↗
A method for applying skeletal traction through osteopenic bone.
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Bone Diseases↗