How are those "lost to follow-up" patients really doing? A compliance comparison in arthroplasty patients.

AIM: To determine whether there is a functional difference between patients who actively follow-up in the office (OFU) and those who are non-compliant with office follow-up visits (NFU). METHODS: We reviewed a consecutive group of 588 patients, who had undergone total joint arthroplasty (TJA), for compliance and functional outcomes at one to two years post-operatively. All patients were given verbal instructions by the primary surgeon to return at one year for routine follow-up visits. Patients that were compliant with the instructions at one year were placed in the OFU cohort, while those who were non-compliant were placed in the NFU cohort. Survey mailings and telephone interviews were utilized to obtain complete follow-up for the cohort. A χ(2) test and an unpaired t test were used for comparison of baseline characteristics. Analysis of covariance was used to compare the mean clinical outcomes after controlling for confounding variables. RESULTS: Complete follow-up data was collected on 554 of the 588 total patients (93%), with 75.5% of patients assigned to the OFU cohort and 24.5% assigned to the NFU cohort. We found significant differences between the cohorts with the OFU group having a higher mean age (P = 0.026) and a greater proportion of females (P = 0.041). No significant differences were found in either the SF12 or WOMAC scores at baseline or at 12 mo postoperative. CONCLUSION: Patients who are compliant to routine follow-up visits at one to two years post-operation do not experience better patient reported outcomes than those that are non-compliant. Additionally, after TJA, older women are more likely to be compliant in following surgeon instructions with regard to follow-up office care.

Longitudinal evaluation of time related femoral neck narrowing after metal-on-metal hip resurfacing.

AIM: To track the short-term neck narrowing changes in Birmingham metal-on-metal hip resurfacing (MOMHR) patients. METHODS: Since 2001, the Center for Hip and Knee Replacement started a registry to prospectively collect data on hip and knee replacement patients. From June 2006 to October 2008, 139 MOMHR were performed at our center by two participate surgeons using Birmingham MOMHR prosthesis (Smith Nephew, United States). It is standard of care for patients to obtain low, anteriorposterior (LAP) pelvis radiographs immediately after MOMHR procedure and then at 3 mo, 1 year and 2 year follow up office visits. Inclusion criteria for the present study included patients who came back for follow up office visit at above mentioned time points and got LAP radiographs. Exclusion criteria include patients who missed more than two follow up time points and those with poor-quality X-rays. Two orthopaedic residency trained research fellows reviewed the X-rays independently at 4 time points, i.e., immediate after surgery, 3 mo, 1 year and 2 year. Neck-to-prosthesis ratio (NPR) was used as main outcome measure. Twenty cases were used as subjects to identify the reliability between two observers. An intraclass correlation coefficient at 0.8 was considered as satisfied. A paired t-test was used to evaluate the significant difference between different time points with P < 0.05 considered to be statistically significant. RESULTS: The mean NPRs were 0.852 ± 0.056, 0.839 ± 0.052, 0.835 ± 0.051, 0.83 ± 0.04 immediately, 3 mo, 1 year and 2 years post-operatively respectively. At 3 mo, NPR was significantly different from immediate postoperative X-ray (P < 0.001). There was no difference between 3 mo and 1 year (P = 0.14) and 2 years (P = 0.53). Femoral neck narrowing (FNN) exceeding 10% of the diameter of the neck was observed in only 4 patients (5.6%) at two years follow up. None of these patients developed a femoral neck fracture (FNF). CONCLUSION: Femoral neck narrowing after MOMHR occurred as early as 3 mo postoperatively, and stabilized thereafter. Excessive FNN was not common in patients within the first two years of surgery and was not correlated with risk of FNF.

Factors affecting response rates to mailed preoperative surveys among arthroplasty patients.

AIM: To identify factors that affect patient response rates to preoperative functional surveys in hip and knee arthroplasty patients. METHODS: From May 2008 to March 2009, 247 patients were scheduled more than 4 wk in advance for hip or knee arthroplasty by one of two participating surgeons at our center. A personalized questionnaire comprised of the Short Form 12 (SF-12) and Western Ontario and McMaster Universities (WOMAC) Index was mailed to patients at random time points ranging from 7 to 101 d prior to surgery. Nine independent factors were documented prospectively, including age, gender, ethnicity, marital status, type of surgery, surgeon, days prior to surgery (DPS) of survey mailing, WOMAC score and SF-12 score. The date of the completed survey receipt was also documented. For non-responders, the surveys were completed with the research team at the hospital upon admission. Multivariate regression and χ(2) analysis were performed with Statistical Analysis Software software. RESULTS: DPS was the only factor that affected patient response. Mailing surveys 26 d to 31 d prior to surgery dates led to a peak response rate of 80% that was significantly higher (P < 0.023) than response rates for patients who were mailed their surveys ≤ 16 d (62.5%), 17 d to 25 d (70%) or ≥ 32 d prior to surgery (55%). No other factors, including preoperative WOMAC and SF-12 scores, significantly influenced response behavior. CONCLUSION: The DPS was independently the most significant predictor of response rates for pre-operative functional data among patients scheduled for hip and knee arthroplasty.

Comparison of total hip and knee arthroplasty cohorts and short-term outcomes from a single-center joint registry.

The purpose of this study was to compare short-term clinical outcomes between total hip arthroplasty (THA) and total knee arthroplasty (TKA) patient cohorts, adjusting for confounding variables including age, sex, body mass index, operative time, length of stay, and preoperative Western Ontario and McMaster Universities and 12-Item Short-Form Health Survey. A total of 349 patients who met inclusion and exclusion criteria created 2 cohorts: THA, 194, and TKA, 155, for statistical analysis via multiple regression and analysis of covariance measures. Outcome measures included Western Ontario and McMaster Universities and 12-Item Short-Form Health Survey data, collected prospectively at baseline and 2 years of follow-up. The current study showed that baseline characteristics of TKA patients have more factors with negative effect on postoperative outcome than THA. However, despite controlling for the possible confounding effect of these variables, THA patients experienced a significantly better functional outcome than TKA patients.

Does ipsilateral knee pain improve after hip arthroplasty?

BACKGROUND: Intraarticular hip disease is commonly acknowledged as a cause of ipsilateral knee pain. However, this is based primarily on observational rather than high-quality evidence-based studies, and it is unclear whether ipsilateral knee pain improves when hip disease has been treated. QUESTIONS/PURPOSES: We asked whether (1) hip disease was associated with preoperative ipsilateral knee pain and (2) ipsilateral knee pain would improve after hip arthroplasty. PATIENTS AND METHODS: We retrospectively assessed knee pain in 255 patients who underwent hip arthroplasties between 2006 and 2008. The WOMAC pain score of each joint was the primary outcome measure, which was obtained prospectively before surgery and at 3 months and 1 year postoperatively. Of the 255 patients, 245 (96%) had followup data obtained at 3 months or 1 year. RESULTS: Preoperatively, ipsilateral knee pain was observed more frequently than contralateral knee pain (55% versus 18%). Preoperative ipsilateral knee pain scores were worse than contralateral knee pain scores (mean, 80 versus 95). Ipsilateral knee pain improved at 3 months and 1 year. When compared with the scores for contralateral knee pain at 3 months (95) and 1 year (96), there were no differences between knees. CONCLUSIONS: Our observations suggest hip disease is associated with ipsilateral knee pain and that it improves after hip arthroplasty. This should be considered during preoperative evaluation for patients with hip and knee pain. LEVEL OF EVIDENCE: Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

The accuracy and reliability of preoperative templating for metal-on-metal hip resurfacing.

The purposes of this study were to evaluate the accuracy and reliability of preoperative templating on conventional radiographs (CRs) for metal-on-metal hip resurfacing and to determine the factors affecting the accuracy. Four observers templated 80 CRs on 2 separate occasions in a blinded fashion. Eight independent variables were evaluated to investigate their effect on the accuracy of templating. The overall accuracy of templating within one size of the actual component was 80.6% for the femoral component and 98.5% for the acetabular component. Overall, the intraobserver and interobserver reliability was fair to substantial (κ = 0.22-0.61). Using multiple regression analysis, surgical time was the only factor that affected the accuracy of predicting the size of the acetabular component (P = .019). We conclude that CR templating for metal-on-metal hip resurfacing is a useful method for preoperative planning of the sizes of the respective implants and that surgeon experience does play a significant role in the accuracy of predicting component size during templating.

The effect of fixation technique on the stiffness of comminuted Vancouver B1 periprosthetic femur fractures.

The purpose of this study was to evaluate the stiffness of 3 different constructs for the fixation of comminuted Vancouver B1 periprosthetic femoral shaft fractures: a single lateral locking plate, a single lateral locking plate plus an anterior strut allograft, and a lateral locking plate plus an anterior locking plate. The axial stiffness, lateral bending stiffness, and torsional stiffness of 10 synthetic periprosthetic femur fracture models were tested. Differences in stiffness between constructs were determined with a 1-way repeated-measures analysis of variance. Fixation technique was found to have a significant effect for all loading modalities (P < .0001). A lateral locked plate plus an anterior locked plate was significantly stiffer than the allograft that in turn was significantly stiffer than the single plate (P < .0001).

Grand rounds: an outbreak of toxic hepatitis among industrial waste disposal workers.

CONTEXT: Industrial waste (which is composed of various toxic chemicals), changes to the disposal process, and addition of chemicals should all be monitored and controlled carefully in the industrial waste industry to reduce the health hazard to workers. CASE PRESENTATION: Five workers in an industrial waste plant developed acute toxic hepatitis, one of whom died after 3 months due to fulminant hepatitis. In the plant, we detected several chemicals with hepatotoxic potential, including pyridine, dimethylformamide, dimethylacetamide, and methylenedianiline. The workers had been working in the high-vapor-generating area of the plant, and the findings of pathologic examination showed typical features of acute toxic hepatitis. DISCUSSION: Infectious hepatitis and drug-induced hepatitis were excluded by laboratory findings, as well as the clinical course of hepatitis. All cases of toxic hepatitis in this plant developed after the change of the disposal process to thermochemical reaction-type treatment using unslaked lime reacted with industrial wastes. During this chemical reaction, vapor containing several toxic materials was generated. Although we could not confirm the definitive causative chemical, we suspect that these cases of hepatitis were caused by one of the hepatotoxic agents or by a synergistic interaction among several of them. RELEVANCE TO CLINICAL OR PROFESSIONAL PRACTICE: In the industrial waste treatment process, the danger of developing toxic hepatitis should be kept in mind, because any subtle change of the treatment process can generate various toxic materials and threaten the workers' health. A mixture of hepatotoxic chemicals can induce clinical manifestations that are quite different from those predicted by the toxic property of a single agent.

Chromosomal aberrations in workers exposed to low levels of benzene: association with genetic polymorphisms.

Benzene and its metabolites damage human lymphocytes, resulting in chromosomal aberrations and aneuploidy. Polymorphisms in the genes for benzene-metabolizing enzymes have been implicated in benzene-associated haematotoxicity. In this study, we examined the specificity of benzene-induced aneuploidy and the influence of genetic polymorphisms (GSTM1, GSTT1, GSTP1, NAT2, NQO1 and CYP2E1) on chromosomal aberrations. In total, 82 benzene-exposed workers from a coke oven plant and 76 matched controls were examined. The benzene concentration in the work-place air ranged from 0.014-0.743 p.p.m. (geometric mean 0.557 p.p.m.). Benzene exposure was associated with significant increases in both monosomy and trisomy of chromosomes 8 and 21. Translocations between chromosomes 8 and 21 [t(8:21)] were eight-fold more frequent in the high-level exposure group compared to the control group. Multiple regression analysis indicated that the frequencies of chromosome aberrations were significantly associated with benzene exposure and polymorphisms in the metabolic enzyme genes. A particular subset of genotypes, which included the GSTM1-null and GSTT1-null genotypes, the slow acetylator type of NAT2, a variant of the NQO1 genotype and the CYP2E1 DraI and RsaI genotypes, were either separately, or in combination, associated with increased frequencies of aneuploidy among the benzene-exposed individuals after adjustments for age, alcohol consumption and smoking. These results suggest that polymorphisms in the genes for benzene-metabolizing enzymes influence the susceptibility of individuals to chromosomal aberrations in relation to benzene exposure.