Femoral vein thrombosis and total hip replacement.

Of 160 patients who underwent total hip replacement, 81 developed venographic evidence of thrombi in the operated leg. In 46 cases (57%) the thrombus originated from the femoral vein, and in 43 of these the exact site of origin was defined by venography. In 34 cases (74%) the thrombus arose from the wall of the femoral vein at the level of the lesser trochanter. This region was studied by intraoperative venography in eight patients undergoing total hip replacement, and in every case severe distortion of the common femoral vein was observed, producing almost total occlusion. We suggest that intraoperative damage to the femoral vein results from manipulation of the leg, and that this is one reason why the operation is followed by a high incidence of deep vein thrombosis in the upper femoral region.     

Antibiotic prophylaxis in total hip replacement.

A controlled prospective trial to compare the efficacy of the antibiotics cephaloridine and flucloxacillin in preventing infection after total hip replacement was conducted at three hospitals. The antibiotic regimens began before surgery, cephaloridine being continued for 12 hours and flucloxacillin for 14 days afterwards. Over an 18-month period 297 patients undergoing a total of 310 hip replacements were entered into the trial and randomly allocated to one of the regimens. The follow-up period ranged from one to two and a half years. All operations were performed in conventional operating theatres; at two of the hospitals these were also used by various other surgical disciplines. Four patients developed deep infection, two having received the cephaloridine and two the flucloxacillin regimen. The overall rate of deep infection was therefore 1.3%. Thus three doses of cephaloridine proved to be as effective as a two-week regimen of flucloxacillin. Giving a prophylactic systemic antibiotic reduced the incidence of infection to a level comparable with that obtained in ultra-clean-air operating enclosures.     

Benefits of total hip replacement to older patients and the community.

The benefits of total hip replacement in 49 people aged 55-84 with osteoarthrosis of the hip were evaluated. The main benefit was relief of symptoms, 40 patients being pain free after operation. Range of hip movement and mobility improved moderately in most patients. After operation most patients were better able to perform certain activities of daily life, though only six were completely independent, the rest requiring aids or help from others. Nevertheless, 18 of the patients'' main helpers estimated that they had more time free of tasks previously performed for the patient. There was a small reduction in the need for community medical resources such as home visits from general practitioners or district nurses. Thirteen patients were still taking antiarthritic drugs. Older patients needed to spend longer in hospital after operation because of complications. It was concluded that total hip replacement contributed to improving the quality of life of patients and their helpers, while also helping to reduce the demand for community health and welfare services.     

Cement mantle fatigue failure in total hip replacement: experimental and computational testing

One possible loosening mechanism of the femoral component in total hip replacement is fatigue cracking of the cement mantle. A computational method capable of simulating this process may therefore be a useful tool in the preclinical evaluation of prospective implants. In this study, we investigated the ability of a computational method to predict fatigue cracking in experimental models of the implanted femur construct. Experimental specimens were fabricated such that cement mantle visualisation was possible throughout the test. Two different implant surface finishes were considered: grit blasted and polished. Loading was applied to represent level gait for two million cycles. Computational (finite element) models were generated to the same geometry as the experimental specimens, with residual stress and porosity simulated in the cement mantle. Cement fatigue and creep were modelled over a simulated two million cycles. For the polished stem surface finish, the predicted fracture locations in the finite element models closely matched those on the experimental specimens, and the recorded stem displacements were also comparable. For the grit blasted stem surface finish, no cement mantle fractures were predicted by the computational method, which was again in agreement with the experimental results. It was concluded that the computational method was capable of predicting cement mantle fracture and subsequent stem displacement for the structure considered.     

Cost-effectiveness of enoxaparin versus warfarin prophylaxis against deep-vein thrombosis after total hip replacement.

OBJECTIVE: To compare the efficacy and cost-effectiveness of enoxaparin, a low-molecular-weight heparin derivative, with that of low-dose warfarin in the prevention of deep-vein thrombosis (DVT) after total hip replacement. DATA SOURCES: English-language articles on enoxaparin and warfarin prophylaxis is patients undergoing total hip replacement published from January 1982 to December 1992. STUDY SELECTION: Four trials of enoxaparin (involving 567 patients) and six trials of warfarin (involving 630) met the following criteria: randomized controlled trial, prophylaxis started no later than 24 hours after surgery and continued for at least 7 days, warfarin dose monitored and adjusted appropriately, enoxaparin dosage 30 mg twice daily, and DVT confirmed by bilateral venography. DATA EXTRACTION: Rates of DVT, cost of prophylaxis, diagnosis and treatment per patient, rate of pulmonary embolism (PE), number of deaths and incremental cost-effectiveness (cost per life-year gained). DATA SYNTHESIS: The pooled rate of DVT was 13.6% with enoxaparin (95% confidence interval [CI] 10.9% to 16.3%) and 20.6% with warfarin (95% CI 17.4% to 23.8%). At a cost of $19.55 per day for enoxaparin the total cost per patient, including prophylaxis and management of DVT, exceeded that per patient receiving warfarin by about $121. For every 10,000 patients treated the use of enoxaparin will prevent 47 cases of DVT, 3 cases of PE and 4 deaths. Thus, the estimated incremental cost-effectiveness of enoxaparin is $29 120 per life-year gained. CONCLUSION: On the basis of current Canadian cost-effectiveness guidelines the results of this study would be considered moderate to strong evidence to adopt enoxaparin prophylaxis against DVT after total hip replacement. However, because of the limited data the estimates are uncertain. Future trials should compare enoxaparin and warfarin and incorporate a prospective economic appraisal.     

Characteristics of sit-to-stand and gait coordination in patients with total hip replacement

Upright posture, standing up from a chair, and gait were analyzed in patients after one-sided total hip replacement and in healthy subjects (control). It was found that the patients predominantly loaded the unoperated leg when they stood quietly or rose from a chair. Subjects’ walking on a 10-m podograph treadmill showed that their walking speed was slower than that of healthy subjects and the swing phase on the side of hip replacement was longer than on the unoperated side. It was assumed that the unequal load on legs during walking, standing, and sit-to-stand performance in patients with total hip replacement was related to the sensory deficit of the artificial joint, leading to the overstrain of the unoperated leg and coxarthrosis in it.     

Bending and fracture of the femoral component in cemented total hip replacement

A computer method was used to make 41 measurements on the geometry of insertion of the femoral component in 200 Charnley total hip replacements. Surgery had been performed at least 12 years before, giving results which were classified as: success (90); fracture (56); or loose (54), according to rigid selection criteria. Fracture was associated with heavier patients in which there was poor proximal fixation of the femoral component but adequate distal fixation. Stems with a medial disposition proximally were more common in the fracture group than in the successful or loose groups. Sequential measurements of bending and subsequent fracture were made on the follow-up radiographs of 24 of the 200 cases (6 fracture and 18 successful). These measurements allowed bending to be detected at an earlier stage than by simple inspection of the radiographs.     

Oral cancer in Scotland: changing incidence and mortality.

OBJECTIVES--To determine the incidence of oral cancer in Scotland between 1960 and 1989 and oral cancer mortality from 1911 to 1989. SETTING--Data were obtained on oral cancer incidence from the information and statistics division of the Common Services Agency of the Scottish Health Service and mortality data from the office of the registrar general for Scotland. RESULTS--Mortality from intraoral cancers in Scotland substantially declined throughout this century until the mid-1970s. This trend, however, was then reversed, and fourfold increases in incidence were observed in younger age groups after 1960. Death rates in these younger age groups increased to levels previously recorded in the 1940s. These increases seemed to be cohort based and may therefore continue into the future. CONCLUSIONS--Reasons for increasing rates among younger age groups are speculative and rely on combining knowledge about risk factors and available ecological data. Though increases in incidence at younger ages do not result in a large change in the number of cases diagnosed, possible similar increases continuing into older ages, when oral cancer is more common, will correspond to a much larger increase in the actual number of cases. Given that such a large attributable risk is associated with tobacco and alcohol, however, these increases may be preventable.     

The relation between resting heart rate and cancer incidence,cancer mortality and all-cause mortality in patients with manifest vascular disease

BackgroundPrevious studies suggest that elevated resting heart rate (RHR) is related to an increased risk of cancer mortality. The aim of this study was to evaluate the relation between RHR and cancer incidence and mortality in patients with vascular disease.MethodsPatients with manifest vascular disease (n = 6007) were prospectively followed-up for cancer incidence and mortality. At baseline, RHR was obtained from an electrocardiogram. The relation between RHR and cancer incidence, cancer mortality and total mortality was assessed using competing risks models.ResultsDuring a median follow-up of 6.0 years (interquartile range: 3.1–9.3) 491 patients (8%) were diagnosed with cancer and 907 (15%) patients died, 248 (27%) died from cancer. After adjustment for potential confounders, the hazard ratio (HR) for incident cancer per 10 beats/min increase in RHR was 1.00 (95% confidence interval [CI]: 0.93–1.07). There was a trend toward an increased risk of colorectal cancer in patients with higher RHR (HR 1.15, 95% CI 0.97–1.36). The risk of all-cause mortality was increased in patients in the highest quartile of RHR compared to the lowest quartile (HR 1.86, 95% CI 1.53–2.27), but no effect of RHR on cancer mortality was observed (HR 1.01, 95% CI 0.70–1.46).ConclusionsIn patients with manifest vascular disease, elevated RHR was related to a higher risk of premature all-cause mortality, but this was not due to increased cancer mortality. RHR was not related to risk of overall cancer incidence, although a relation between elevated RHR and incident colorectal cancer risk could not be ruled out.