Distal rotational alignment of the Chinese femur and its relevance in total knee arthroplasty

The rotational alignments of the distal femur in southern Chinese subjects were investigated. Chinese femurs are significantly more externally rotated. This is new evidence to suggest a racial difference in the distal femoral geometry. During total knee arthroplasty, a common recommendation is to allow 4 degrees of external rotation. The clinical significance of our study is that this need to be modified to 6 degrees for Chinese women and 5 degrees for Chinese men. This racial difference can be incorporated into a new concept of "a mountain and a molehill." This concept is presented in this report.

Posterior cruciate ligament-substituting total knee arthroplasty in young rheumatoid patients with advanced knee involvement

The integrity and strength of the posterior cruciate ligament (PCL) in the rheumatoid knee are known to be suboptimal. However, the results of PCL-substituting total knee arthroplasty in rheumatoid patients are not well documented. We reviewed 86 PCL-substituting total knee arthroplasties in 52 rheumatoid patients with grade IV or V radiographic disease. The mean age at surgery was 41.9 years. All patients underwent follow-up evaluation for an average of 7.8 years. Revision was performed for 1 knee because of aseptic loosening of the tibial component, and for 3 knees because of deep infection. An isolated insert exchange was performed on one knee. Using revision of any component for aseptic loosening or radiographic loosening as the end point, the mean 10-year survival rate was 94.0%.

Recurrent dislocation of total knee arthroplasty: an unusual cause

We report an unusual case of recurrent dislocation of posterior stabilized total knee arthroplasty (TKA) secondary to fracture of the polyethylene insert. Recurrent dislocation occurred 21 months after primary TKA. Fractured polyethylene insert was noted as an abnormal radiolucent shadow on postoperative radiographs and was confirmed by an arthrogram. At revision surgery, disintegration of the insert, including the tibial post, was found. We recommend careful scrutiny of the integrity of the polyethylene insert at the time of follow-up evaluation in cases of TKA dislocation.

The use of complementary and alternative medicine by asthma patients

BACKGROUND

Use of complementary and alternative medicines (CAM) by asthmatic patients is increasing. Data on the prevalence of CAM use in asthma are limited, and the motivation for patients to seek CAM therapy is uncertain.

AIM

To determine the prevalence and pattern of use of complementary therapies in adults treated for asthma in primary care in Singapore, and the demographic and clinical factors associated with their use.

DESIGN

Cross-sectional study.

SETTING

Five primary care clinics in Singapore.

METHODS

Adult patients with asthma (n = 802) received a structured questionnaire interview and clinical assessment that included demographic and clinical variables (clinical status, patient's knowledge, self-care and healthcare-seeking behaviour, and spirometric measurements) and detailed information on CAM use in the past one year.

RESULTS

CAM use in the past year was reported by 27.2%, including animal food products (12.3%), herbs (10.3%), herbal-based proprietary medicines (3.2%), and acupuncture or reflexology (1%). The use of CAM was significantly associated with Chinese ethnicity, longer disease duration, moderate and severe persistent asthma, FEV(1)/FVC < 80%, lack of positive response to treatment in the past year, higher patient knowledge score, and multiple sources of care providers.

DISCUSSION

The use of CAM is highly prevalent in Asian patients treated for asthma in primary care, and is associated with cultural and clinical factors reflecting a need to improve care.

Efficacy of a single dose of cefazolin as a prophylactic antibiotic in primary arthroplasty

We analyzed the wound infection rate of 1,367 primary total hip and knee arthroplasties performed between 1991 and 1999. Two hundred and fifteen arthroplasties were performed with 3 doses (3 x 750 mg) of cefuroxime, and 1,152 arthroplasties were performed with a single preoperative dose (1 x 1 g) of cefazolin as antimicrobial prophylaxis. All wound infections that occurred within 2 years of the index surgery were analyzed. The deep wound infection rate of total hip arthroplasty was 1.1% (95% confidence interval [CI], 0%-3.3%) in the cefuroxime group and 1.1% (95% CI, 0%-2.2%) in the cefazolin group (Fisher's exact test, P = 1.0). The deep wound infection rate of total knee arthroplasty in the cefuroxime group (1.6%; 95% CI, 0%-3.8%) was not significantly different from the cefazolin group (1.0%; 95% CI, 0.3%-1.7%) (Fisher's exact test, P =.63). We concluded that a single dose (1 g) of cefazolin given at anesthetic induction offered similar protection to 3 doses (3 x 750 mg) of cefuroxime in preventing infection in primary total joint arthroplasty.

Practicing cementing technique with a toy: Play-Doh

Cementing technique has direct impact on the longevity of a total hip arthroplasty, and the proper technique can only be acquired by practice. Using acrylic bone cement to practice cementing technique in a bioskill workshop is expensive and can cause occupational hazards. In this article, we describe a toy that can replace acrylic bone cement in a bioskill workshop. Play-Doh (Hasbro Inc, Pawtucket, RI) is an inexpensive, reusable and non-toxic modeling toy that mimics the doughy phase of acrylic bone cement.

Trends and ethnic differences in hospital admissions and mortality for congestive heart failure in the elderly in Singapore, 1991 to 1998

OBJECTIVES

To describe trends in hospital admissions and mortality from congestive heart failure in the elderly population aged 65 years and over in Singapore, 1991 to 1998.

DESIGN

Analysis of trends and population subgroup differences in rates of hospital admission and mortality for a primary diagnosis of congestive heart failure, classified as ICD-9, codes 428, 402.0, 402.11, and 402.91.

SETTING

The state of Singapore (multiethnic population of three million: Chinese 77%, Malay 14%, Indian 8%).

RESULTS

Congestive heart failure accounted for 4.5% of all hospital admissions and 2.5% of overall mortality in this age group. Age adjusted hospital admission rates for congestive heart failure increased by 38% (from 85.4 per 10 000 in 1991 to 110.3 per 10 000 in 1998), while mortality decreased by 20% (from 7.3 per 10 000 in 1991 to 6.1 per 10 000 in 1998). The decline in mortality was greater in women than in men. There were no sex differences in the rates of hospital admission, but there were significant ethnic differences in admissions and mortality. Thus hospital admissions for congestive heart failure were about 35% higher in both Malays and Indians than in Chinese; and mortality was 3.5 times higher in Malays, but was about the same in Indians and Chinese. Over the period studied, mortality from congestive heart failure declined in both Chinese and Indians, but rose in Malays. The increases in hospital admissions were similar in both sexes and all ethnic groups.

CONCLUSIONS

An increasing rate of hospital admission accompanied by declining mortality from congestive heart failure is occurring in elderly people in this Asian multiethnic population. However, there are pronounced ethnic differences, with both Malays and Indians showing higher hospital admission rates than Chinese, and Malays showing a rising mortality as opposed to the falling mortality in the other ethnic groups.

The shape and size of femoral components in revision total hip arthroplasty among Chinese patients

OBJECTIVE

39 sets of preoperative hip X-rays were studied to find out whether Chinese patients need revision femoral components with a different shape and size from western patients.

METHODS

From July 1998 to June 2001, the pre-revision X-rays of 39 revision total hip replacements among 38 Chinese patients (21 men and 17 women) were studied. The component size that produced the best distal canal-filling in the anteroposterior X-ray was determined by using templates of 200-mm femoral components used commonly for Caucasian patients.

RESULTS

The diameter of the component needed was 13.5 mm or less in 54% of cases, compared with only 17% for Caucasian patients as reported in the literature (p<0.01). When lateral templates of the corresponding size were put over the lateral X-rays, the anterior cortex of the 200-mm straight stem was shown to have thinned by 2.0 mm or more in 36% of hips; for 200-mm bowed stem, there was thinning of the anterior cortex by 2.0 mm or more in only 5% of hips (p<0.01).

CONCLUSION

Chinese patients are likely to need smaller femoral components than Caucasian patients, and may benefit from bowed-stem components in femoral revision.

Full weight bearing after non-cemented total hip replacement is compatible with satisfactory results

Two matched groups of 29 patients underwent hydroxyapatite-coated non-cemented total hip replacement. One group was started on immediate protected-weight-bearing walking and the other group was started on immediate full-weight-bearing walking. They were followed up regularly for 2 years. They were assessed with Harris hip score clinically and Engh's criteria of osteo-integration radiographically. No difference was found between the two groups. All patients had excellent clinical outcome after hip replacement, and all femoral stems were stable radiographically. Patients can walk with full weight bearing safely immediate after hydroxyapatite-coated non-cemented total hip replacement.

Avoidable hospitalisation rates in Singapore, 1991-1998: assessing trends and inequities of quality in primary care

STUDY OBJECTIVES

To assess avoidable hospitalisation as an indicator of quality of primary care by examining trends and gender and ethnic variations.

DESIGN AND SETTING

Aggregated nationwide data in Singapore from 1991 to1998 were analysed for hospitalisations for chronic diseases that are avoidable by timely, appropriate, and effective primary care: asthma, congestive heart failure, chronic obstructive pulmonary disease, diabetes mellitus, and hypertension (avoidable hospitalisations).

MAIN RESULTS

Of a total of 1 479 494 hospitalisations, 6.7% were for ambulatory care sensitive conditions (ACSC). The annual rate of avoidable hospitalisation was 29.4 per 10 000 population. Women had lower rates of avoidable hospitalisations than men (22.4 versus 29.5 per 10 000), as well as for total hospitalisations (496.2 versus 515.5 per 10 000). Adjusted for total hospitalisation, men were 1.3 times more likely than women to be hospitalised for ACSC. With similar adjustments for baseline utilisation, Indian and Malays had 1.7 and 1.8 times higher rates of avoidable hospitalisations than Chinese. Avoidable hospitalisation decline was -9.1% overall; greater in men (-11.8%) than in women (-5.3%); greater for Chinese (-15.8%), than Malays (-1.1%) and Indians (increase of +4.3%).

CONCLUSION

Gender and ethnic differences and declining trends in avoidable hospitalisation demonstrated in this study suggest that avoidable hospitalisation rates are a sensitive indicator for assessing quality of primary ambulatory care.

Review article: knee flexion after total knee arthroplasty

Many factors affect or predict the flexion range achieved after total knee arthroplasty. While the knees that have good preoperative flexion have better final flexion, knees with good preoperative flexion do lose some flexion whereas those with poor preoperative flexion can gain flexion. Although studies of different prosthetic designs have produced conflicting results, recent studies appear to favour posterior cruciate ligament (PCL)--substituting over PCL-retaining prostheses. Several factors related to surgical techniques have been found to be important. These include the tightness of the retained posterior cruciate ligament, the elevation of the joint line, increased patellar thickness, and a trapezoidal flexion gap. Vigorous rehabilitation after surgery appears useful, while continuous passive motion has not been found to be effective. Obesity and previous surgery are poor prognostic factors; certain cultural factors, such as the Japanese style of sitting, offer 'unintentional' passive flexion and result in patients with better range. If the flexion after surgery is unsatisfactory, manipulation under anaesthesia within 3 months of the total knee arthroplasty can be beneficial.

Influenza in Singapore: assessing the burden of illness in the community

INTRODUCTION

Influenza infection has significant morbidity and mortality. The social and economic costs from work absence in the working population and from hospitalisations in the elderly are considerable. Meta-analyses of cohort and randomised controlled studies indicate that influenza vaccination is effective in preventing respiratory illness, hospitalization, pneumonia and death in 50% to 68% of cases. In Singapore, data on the disease burden from influenza are sparse and no official recommendation on influenza vaccination exists.

METHOD

We estimated the disease burden of influenza-like illness (ILI), influenza infection in the general adult population, and hospitalisations and deaths from pneumonia and influenza, from routine official and published sources, and hoc community sample surveys, national virological surveillance, hospitalization and mortality data.

RESULTS

In a resident population of 3 million people, there were 4.2 million cases of ILI in a typical non-epidemic year, 3.5 million visits to the doctor and 2.1 million days of work absence due to ILI. Data from the National Influenza Surveillance Programme indicated that about 15% of patients with ILI were positive for influenza isolates. We therefore estimated 630,000 cases of influenza virus infection cases a year, giving rise to 520,000 sick visits and 315,000 days of sick absence from work. About 4200 elderly (65+) persons were hospitalised for pneumonia and influenza, resulting in about 1450 deaths every year. The literature suggests a vaccine efficacy of about 50% of preventing influenza and its complications, including hospitalizations and deaths. This indicates that at least 315,000 cases of influenza virus infection, 258,000 sick visits, and 157,000 lost days from work in the whole population, and 2100 hospitalisations and 600 deaths from pneumonia in the elderly are potentially preventable by vaccination each year.

CONCLUSION

Influenza poses a considerable burden of illness in the community and the potential benefits from influenza vaccination are substantial.

Rhinitis: do diagnostic criteria affect the prevalence and treatment?

BACKGROUND

Rhinitis is one of the world's most common health problems. Diagnostic criteria used in community surveys may affect reported prevalence and treatment.

METHODS

A proportionately stratified random sample study was performed to investigate the prevalence, comorbidities and management of community-based patients with rhinitis in the tropical urban city of Singapore.

RESULTS

The prevalence of at least one, two, three, or four nasal symptoms on most days during the past year in our study population was 25.5%, 13.1%, 6.5%, and 3.0%, respectively. Based on the definition of 'rhinitis' by the International Consensus Report (ICR), the prevalence was 13.1% in Singapore. There was significantly higher prevalence of self-reported allergy, asthma, and common cold/influenza-like illness among the rhinitis group. In the 53% of rhinitis subjects seeking for medical help, 71% visited a primary care physician and 20% an otolaryngologist. Treatments as reported by patients were decongestants (topical or oral) 27%, antibiotics 12%, antihistamines 6%, nasal steroids 3%, surgery 2%, traditional methods 28%, and 22% did not know what medication they had. Subjects considered the effectiveness of treatment unsatisfactory because the majority of them had only partial or no relief with any treatment.

CONCLUSIONS

The standardization of the definition of rhinitis in epidemiological studies is of crucial importance, especially when comparing the prevalence between studies. Appropriate patient education by physicians with a good understanding of the nature of rhinitis and the available treatment options (e.g. evidenced-based efficacy, safety, and a good cost-benefit ratio) will maximize patient compliance and treatment outcomes.

Temporal trends and ethnic variations in amenable mortality in Singapore 1965-1994: the impact of health care in transition

BACKGROUND

Amenable mortality is used to assess the effects of health care services on gains in mortality outcomes. Possibly differing patterns of trends in amenable mortality may be expected in economically less developed countries, which have undergone rapid epidemiological transition and recent reforms in health care systems, but such studies are scarce. This study was set up to examine the trends in amenable mortality in Singapore from 1965 to 1994; to estimate the relative impact of medical care and primary preventive policy measures in terms of gains in mortality outcomes; to examine ethnic differences in amenable mortality among Chinese, Malays and Indians.

METHODS

Age-standardized mortality rates were calculated for 16 amenable causes of death in Singapore for six 5-year periods (1965-1969,..., 1990-1994), and for each of the three main ethnic groups for three periods (1989-1991, 1992-1994, 1995- 1997). Amenable mortality rates were divided into those which can be reduced by timely therapeutic care for 'treatable' conditions (e.g. asthma and appendicitis), or by primary preventive measures for 'preventable' conditions (e.g. lung cancer and motor vehicle injury).

RESULTS

Amenable mortality was higher in males (age-standardized rate 109.7 per 100 000 population) than in females (age-standardized rate 60.7 per 100 000 population). Amenable mortality declined by 1.77% a year in males and 1.72% a year in females. By comparison, the average yearly decline in non-amenable mortality was 0.91% in males and 1.17% in females. The decline in amenable mortality was largely due to 'treatable' causes rather than a decline in mortality due to 'preventable' causes of death. Amenable mortality was lowest for Chinese and highest for Malays. Over the recent 9-year period from 1989 to 1997, amenable mortality declined more in Chinese than in Malays and Indians. However, Indian females showed by far the sharpest decline, whereas Indian males, by contrast, showed an increase in amenable mortality, due to both treatable and preventable causes.

CONCLUSIONS

In line with findings from European countries, amenable mortality in Singapore declined more than non-amenable mortality. There were more significant gains in mortality outcomes from medical care interventions than from primary preventive policy measures. Gender and ethnic differences in amenable mortality were also observed, highlighting issues of socioeconomic equities to be addressed in the financing and delivery of health care.

The performance of three vacuum-mixing cement guns--a comparison of the fatigue properties of simplex P cement

We tested three commercially available cement-mixing systems (Howmedica, Summit and Stryker). After mixing the cement was allowed to cure in metal moulds under standard conditions. Sixty-nine cement blocks were produced. The fatigue behavior of the blocks was tested until failure. A wide scattering of results was observed in all the three systems. Uneven mixing of the polymer and monomer was observed in the Howmedica system. A significantly stronger cement (P=0.018) was produced with the Stryker system.

Cementless total hip arthroplasty in young Chinese patients: a comparison of 2 different prostheses

Sixty-one primary cementless total hip arthroplasties were performed in 45 Chinese patients <40 years old. There were 27 Anatomic Medullary Locking (AML, Depuy, Warsaw, IN) prostheses and 34 Porous Coated Anatomic (PCA, Howmedica, Rutherford, NJ) prostheses. The average follow-up was 7.6 years (range, 3-11 years). Ten hips (16%) were reoperated; the reason was polyethylene wear with or without osteolysis in 7 hips. Osteolytic lesion was present in 34 hips (56%). The cumulative successful rate at 10 years was 67% using reoperation for any reason as the endpoint. The cumulative successful rate was 98%, however, if revision for aseptic loosening was used as the endpoint. The 2 prostheses did not show significant differences in most parameters except that the PCA hips had significantly more acetabular loosening (P =.02) and periprosthetic osteolysis (P =.01).

Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women

BACKGROUND

Previous studies have not found a consistent association between exposure to domestic cooking using gas appliances and exacerbation of asthma. We investigated the immediate airflow response to acute exposure from single episodes of gas cooking, and peak airflow variability from continued exposure to repeated episodes of gas cooking in a group of non-smoking asthmatic women.

METHODS

Sixteen adult non-smoking women with mild to severe persistent asthma were studied. The acute short term level of nitrogen dioxide (NO2) during gas cooking episodes and the mean exposure to NO2 from repeated gas cooking episodes were measured over a 2 week period, as well as proxy measures of frequency of cooking on each day and the length of time spent cooking each day. Their asthma status was monitored using peak expiratory flow rates (PEFR) before and after cooking, 2 week self-recorded serial readings of PEFR, respiratory symptom severity score, and use of rescue bronchodilators for acute asthma attacks.

RESULTS

Cooking was significantly associated with an immediate mean fall in PEFR of 3.4% (p=0.015, paired t test). The acute short term NO2 level during cooking was significantly correlated with the fall in PEFR (r=–0.579; p=0.019). The frequency of cooking over a 2 week period was positively correlated with the mean exposure to NO2(r=0.529; p=0.042). Continued exposure to NO2 over a 2 week period was associated significantly with increased frequency of rescue bronchodilator usage for asthma attacks (r=0.597; p=0.031). However, it was negatively associated with PEFR variability (r=–0.512; p=0.051) and respiratory symptom severity score (r= –0.567; p=0.043), probably due to the masking effects of bronchodilator treatment.

CONCLUSIONS

Acute short term exposure to NO2 from single episodes of gas cooking is associated with immediate airflow limitation. Continued exposure from repeated episodes of gas cooking in asthmatic women is associated with greater use of rescue bronchodilators.

Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women

BACKGROUND

Previous studies have not found a consistent association between exposure to domestic cooking using gas appliances and exacerbation of asthma. We investigated the immediate airflow response to acute exposure from single episodes of gas cooking, and peak airflow variability from continued exposure to repeated episodes of gas cooking in a group of non-smoking asthmatic women.

METHODS

Sixteen adult non-smoking women with mild to severe persistent asthma were studied. The acute short term level of nitrogen dioxide (NO2) during gas cooking episodes and the mean exposure to NO2 from repeated gas cooking episodes were measured over a 2 week period, as well as proxy measures of frequency of cooking on each day and the length of time spent cooking each day. Their asthma status was monitored using peak expiratory flow rates (PEFR) before and after cooking, 2 week self-recorded serial readings of PEFR, respiratory symptom severity score, and use of rescue bronchodilators for acute asthma attacks.

RESULTS

Cooking was significantly associated with an immediate mean fall in PEFR of 3.4% (p=0.015, paired t test). The acute short term NO2 level during cooking was significantly correlated with the fall in PEFR (r=-0.579; p=0.019). The frequency of cooking over a 2 week period was positively correlated with the mean exposure to NO2 (r=0.529; p=0.042). Continued exposure to NO2 over a 2 week period was associated significantly with increased frequency of rescue bronchodilator usage for asthma attacks (r=0.597; p=0.031). However, it was negatively associated with PEFR variability (r=-0.512; p=0.051) and respiratory symptom severity score (r= -0.567; p=0.043), probably due to the masking effects of bronchodilator treatment.

CONCLUSIONS

Acute short term exposure to NO2 from single episodes of gas cooking is associated with immediate airflow limitation. Continued exposure from repeated episodes of gas cooking in asthmatic women is associated with greater use of rescue bronchodilators.

Radiological progression and its predictive risk factors in silicosis

OBJECTIVES

To investigate the risk factors predicting radiological progression in silicosis in a prospective cohort study of patients with silicosis who were previously exposed to silica from granite dust.

METHODS

From among a total of 260 patients with silicosis contracted from granite work, 141 with available serial chest x ray films of acceptable quality taken over a period of 2 to 17 (mean 7.5) years, were selected for study. Ninety four (66.7%) had ended exposure 5 or more years previously (mean 10.1 years, maximum 28 years). Radiological progression was assessed by paired comparison of the initial and most recent radiographs, with two or more steps of increase in profusion of small opacities according to the 12 point scale of the International Labour Organisation (ILO) classification of radiographs of pneumoconiosis, taken from the majority reading by a panel of three independent readers.

RESULTS

Overall, 37% of patients with silicosis had radiological evidence of progression. From the initial radiographs, 24 (31.6%) of those with radiological profusion category 1, 15 (37.5%) of those with radiological profusion category 2, and 13 (52%) of those with complicated silicosis (including all seven with category 3 profusion of small opacities) showed radiological progression. As expected, progression was more likely to be found after longer periods of follow up (the interval between the two chest x ray films) with a 20% increased odds of progression for every additional year of follow up. After adjustment for varying intervals of follow up, the probability of radiological progression was found to be significant if large opacities were present in the initial chest x ray film. Progression was also less likely to be found among those who had ended exposure to silica longer ago, although the result was of borderline significance (p=0.07). Tuberculosis was also associated with increased likelihood of progression (borderline significance).

CONCLUSIONS

There is a high probability of radiological progression in silicosis after high levels of exposure to granite dust among workers who were followed up for up to 17 years. A significant risk factor is the extent of radiological opacities in the initial chest x ray film. The probability of progression is also likely to be reduced with longer periods after the end of exposure.

Bilateral total knee arthroplasty: One mobile-bearing and one fixed-bearing

We compared the early results of mobile-bearing knee prosthesis with fixed-bearing knee prosthesis in 16 patients who had one-stage, sequential, bilateral replacements. In each patient, a Low Contact Stress (LCS, Depuy) rotating-platform prosthesis was inserted in one side, and an Anatomic Modular Knee (AMK, Depuy) posterior-stabilised prosthesis was inserted in the other side. The same surgical routines were adopted for both sides in each patient. There were significant improvements in the Knee Society knee score and functional score, as well as the Oxford Knee score after both mobile-bearing and fixed-bearing knee replacements (p<0.001). However, we could not find any significant difference between the clinical results of the two prostheses. The authors early experience with the mobile-bearing total knee prosthesis was as favourable as the medium-term experience of the fixed-bearing total knee prosthesis in this prospective, match-pair study.

The design and assessment of questionnaires in clinical research

Questionnaires are one of the most commonly used tools for data collection in clinical research. Despite its simplicity and convenience of use, the design of questionnaire instruments that accurately measure health status and their determinants is nevertheless a difficult and challenging task.We review the two most important issues which are reliability and validity. Reliability can be defined as the degree to which a measure gives 'consistent' or 'reproducible' values when applied in different situations. Validity refers to the extent in which the true value of a variable is correctly measured by the instrument. For different types of questionnaire measurement instruments, specific issues of content, construct and criterion validity should be appropriately addressed. Accuracy in questionnaire-based measurement in clinical studies is achieved by paying attention to the relevant specific issues of reliability and validity during development and testing of such questionnaires.

Unusual complication associated with femoral intramedullary alignment guide in total knee arthroplasty

The few reported complications related to the use of a femoral intramedullary alignment guide in total knee arthroplasty include increase in perioperative bleeding and fat embolism. We report 3 patients suffering from an unusual complication, concerning trapping of the tibial locking pin inside the intramedullary canal of the femur secondary to the use of an intramedullary alignment guide. Methods of retrieving the locking pin from the medullary canal are discussed.

Charnley total hip arthroplasty in Chinese patients less than 40 years old

Forty-seven total hip arthroplasties were reviewed in 33 Chinese patients who were <40 years old at the time of operation. The preoperative diagnosis was avascular necrosis in 40% of the hips. A Charnley prosthesis was inserted using early cementing techniques in every hip. The average follow-up was 14.9 years (range, 6.9-21.1 years). The mean preoperative Harris hip score was 43.8 (range, 26-74), and the mean score at latest follow-up was 87.7 (range, 74-99) for the surviving hips. Thirty hips (63%) were revised, and 1 hip was removed because of late deep infection. The main cause of failure was aseptic loosening of the acetabular component. Using revision and radiologic loosening as endpoints, the cumulative survival rate for the acetabular component was 86.3% at 10 years and 27.0% at 15 years. The survival of the femoral components was 81.3% at 15 years. Patients with avascular necrosis had a higher failure rate than patients with other diagnoses (P =.001). An area of cement mantle that was <2 mm thick affected adversely the survival rate of the acetabular components (P =.04).