Fracture of the neck of the femur after surface arthroplasty of the hip

BACKGROUND: There are two main modes of failure of the femur following surface arthroplasty of the hip: femoral neck fracture and aseptic loosening. The purpose of the present study was to present our experience with femoral neck fractures that occurred after metal-on-metal hybrid surface arthroplasty and to assess their cause. METHODS: A series of 600 metal-on-metal surface arthroplasties was performed between late 1996 and early 2003. Failures that occurred during this period were assessed radiographically and with implant retrieval analysis to determine their cause. RESULTS: Five femoral neck fractures occurred in this series (prevalence, 0.83%). Four of the five fractures occurred at the component-neck junction within the first five months (average, three months) after surgery. All five fractures were associated with a traumatic episode, but all five also were associated with structural and/or technical risk factors, which we believe weakened the femoral neck. The most important technical deficiency that contributed to three of the five fractures was the failure to cover all of the reamed bone with the component. CONCLUSIONS: It is important to avoid or at least minimize notching of the femoral neck by performing the cylindrical reaming at the recommended angle of 140 degrees and to stop reaming before the reamer touches the lateral cortex. Osteophytes should be removed judiciously only if there is notable impingement when the hip is flexed to 90 degrees and internally rotated. We believe that understanding the factors that contribute to femoral neck fracture after surface arthroplasty may reduce the prevalence of this mode of failure.     

Management of Ficat stage III and IV osteonecrosis of the hip

Management of Ficat stage III and IV osteonecrosis of the hip remains controversial. Because patients usually require a surgical intervention in their mid 30s, the initial procedure is often the first step in a lifelong treatment plan. Long-term results of total hip arthroplasty in these young, active patients have been disappointing. New alternative bearing surfaces (metal-on-metal, ceramic-on-ceramic, and highly cross-linked polyethylene) and improved methods of fixation may lead to better long-term results. Nevertheless, bone- and joint-preserving procedures, such as free-vascularized fibular graft, trapdoor grafting, redirectional osteotomy, or hemiresurfacing hip arthroplasty, should be considered. The choice of option depends on patient age, the cause of osteonecrosis, the extent of femoral head involvement, and the condition of the acetabular articular cartilage. The goals of treatment are to relieve pain, improve function, minimize morbidity, and maintain options for secondary procedures.     

Hemiresurfacing arthroplasty of the hip for failed free-vascularized fibular graft

Management of Ficat stage III and IV osteonecrosis of the hip remains challenging, with the average patient aged in the mid 30s. Joint- and bone-preserving procedures such as free vascularized fibular graft, redirectional osteotomies, and hemiresurfacing hip arthroplasty are often considered. If these treatments fail, that is, after progression of joint destruction or persistent pain and decreasing function, total hip arthroplasty is often the procedure of choice. We describe the case of a patient with failed bilateral free vascularized fibular graft treated with bilateral hemiresurfacing arthroplasty.     

Fate of cementless acetabular components retained during revision total hip arthroplasty

BACKGROUND: Removal of a well-fixed cementless acetabular component can result in increased operative time and postoperative morbidity. The objectives of this retrospective study were to determine whether retention of a well-fixed acetabular component at the time of isolated femoral revision was compatible with long-term socket survival. METHODS: The records of eighty-three consecutive patients (ninety hips) in whom a well-fixed cementless socket had been retained during revision of a femoral component were reviewed. The mean age of the patients was 48.7 years at the time of the primary arthroplasty and 54.1 years at the time of femoral revision. The radiographic analysis was based on anteroposterior radiographs and was performed by a single independent reviewer. The intraoperative criterion for stability of the socket was the absence of movement at the bone-implant interface during the application of direct pressure to the edges of the socket in four quadrants with use of a metallic pusher. RESULTS: At the time of the isolated femoral revision, no socket demonstrated a radiolucent line measuring >1 mm in any two zones and forty of the ninety hips had periacetabular osteolysis. The mean size of the osteolytic lesions was 5.71 cm(2) (range, 0.4 to 24.2 cm(2)), and twenty-eight of the forty hips underwent bone-grafting. The mean duration of follow-up was 9.7 years after the isolated femoral revision and 14.9 years after the primary arthroplasty. Five acetabular sockets were revised at a mean of 6.8 years after the femoral revision. Only one of these sockets had failed because of aseptic loosening. With revision of the acetabular component for any reason as the end point, the survival rate was 98.7% at five years and 93.5% at ten years after the femoral revision and 100% at ten years and 93.9% at fifteen years after the primary arthroplasty. No hip showed recurrence or expansion of periacetabular osteolysis. The prevalence of dislocation was 16% (fourteen of ninety). CONCLUSIONS: Revision of a stable, cementless acetabular component solely on the basis of its duration in vivo or the presence of periacetabular osteolysis does not appear to be warranted. Retention of the socket with grafting of larger periacetabular osteolytic lesions appears to be consistent with satisfactory socket longevity.     

A-mode ultrasound-based registration in computer-aided surgery of the skull

OBJECTIVE: To evaluate the integration and accuracy of A (amplitude)-mode ultrasound-based surface matching for noninvasive registration of the head into a frameless computer-aided surgery system for otorhinology and skull base surgery. DESIGN: Experimental study and case series. SETTING: Academic medical center. PATIENTS: Twelve patients underwent anterior and paranasal skull base surgery with the routine use of a computer-aided surgery system. INTERVENTIONS: A computer-aided surgery system, based on an optoelectronic localizer, was used to track the skull and the surgical tools, including the A-mode ultrasound probe. The A-mode probe was a 10-MHz immersion transducer. An acoustic lens attached to the transducer focused the ultrasonic beam to a depth of 1 to 10 mm. Accuracy tests were performed for the ultrasound setup. Different surface point distributions were evaluated with respect to matching accuracy on a human cadaver skull specimen equipped with fiducial markers. The matching comparison was based on the fiducial registration error. For the clinical evaluation, the laboratory setup was transferred to the operating room. MAIN OUTCOME MEASURES: Noninvasive registration of the skull by using A-mode ultrasound in computer-aided surgery (practical and clinical measurements). RESULTS: The accuracy tests on the human skull specimen revealed that the mean +/- SD fiducial registration error was 1.00 +/- 0.19 mm in the best series for A-mode ultrasound surface matchings and was robust with respect to different sets of surface points. The mean +/- SD root mean square error from the 12 A-mode ultrasound matchings in the patient study was 0.49 +/- 0.20 mm. CONCLUSION: A-mode ultrasound surface matching can be used as a noninvasive and accurate registration procedure in computer-aided surgery of the head.     

Aerobic exercise in adolescents with obesity: preliminary evaluation of a modular training program and the modified shuttle test

Background  

Increasing activity levels in adolescents with obesity requires the development of exercise programs that are both attractive to adolescents and easily reproducible. The aim of this study was to develop a modular aerobic training program for adolescents with severe obesity, with a focus on variety, individual targets and acquiring physical skills. We report here the effects on aerobic fitness from a pilot study. Furthermore, we examined the feasibility of the modified shuttle test (MST) as an outcome parameter for aerobic fitness in adolescents with severe obesity.     

复方葆春袋泡茶质量标准研究

目的：制订复方葆春袋泡茶质量标准。方法：双波长薄层扫描法测定了五味子乙素的量,对淫羊藿,五味子,女贞子进行了薄层色谱鉴别。结果;加样回收率平均为９７．１５％（ＲＳＤ＝１．２％,ｎ＝５）,标准曲线ｒ＝０．９９９１,重复性ＲＳＤ＝１．４％（ｎ＝６）精密度ＲＳＤ＝２．３％（ｎ＝６）,结论,方法稳定,可靠,可作为该制剂的质量控制方法之一。     

Return of autologous blood donors as homologous blood donors

Autologous blood donors (ABDs) have been reported to have favorable attitudes toward returning as homologous blood donors (HBDs), but the frequency of return has not been well documented. ABDs eligible by history to be HBDs were followed at one blood center: 255 donating for elective surgery and 234 donating during pregnancy were followed for an average of 18 months and 20 months, respectively, from time of eligibility after surgery or postpartum. Male ABDs had a higher rate of return as HBDs, as 34 percent (21/62) returned to donate an average of 3 units, whereas 13 percent (56/427) of female ABDs returned as HBDs to donate an average of 2 units. Although a history of donation was associated with a higher rate of return (30%, 34/113), 11 percent (43/376) of ABDs with no history as HBDs returned to donate homologous units, despite having been recruited less frequently than prior HBDs. Overall, all male ABDs and female ABDs with an HBD history returned most frequently. The extra effort required for an autologous donor program may result in the recruitment of new donors into the HBD pool.     

Pesticide assessment: Protecting public health on the home turf

Pesticide regulation is examined in the context of Health Canada’s Pest Management Regulatory Agency’s assessment of the chlorophenoxy herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) for turf. 2,4-D is the most common herbicide used to kill weeds in grass.The medical literature does not uniformly indicate harms from herbicides. However, the balance of epidemiological research suggests that 2,4-D can be persuasively linked to cancers, neurological impairment and reproductive problems. These may arise from 2,4-D itself, from breakdown products or dioxin contamination, or from a combination of chemicals.Regulators rely largely on toxicology, but experiments may not replicate exposures from 2,4-D application to lawns because environmental breakdown products (eg, 2,4-dichlorophenol) may not accumulate and selected herbicides are possibly less contaminated. Dioxins are bioaccumulative chemicals that may cause cancer, harm neurological development, impair reproduction, disrupt the endocrine system and alter immune function. No dioxin analyses were submitted to the Pest Management Regulatory Agency, and the principal contaminants of 2,4-D are not among the 17 congeners covered in pesticide regulation. Independent assessment of all dioxins is needed, in tissues and in the environment.The 2,4-D assessment does not approach standards for ethics, rigour or transparency in medical research. Canada needs a stronger regulator for pesticides. Potentially toxic chemicals should not be registered when more benign solutions exist, risks are not clearly quantifiable or potential risks outweigh benefits. Until landscaping pesticides are curtailed nationally, local bylaws and Quebec’s Pesticide Code are prudent measures to protect public health. Physicians have a role in public education regarding pesticides.