VLBI measurement of the vector baseline between geodetic antennas at Kokee Park Geophysical Observatory, Hawaii.

We measured the components of the 31-m-long vector between the two very-long-baseline interferometry (VLBI) antennas at the Kokee Park Geophysical Observatory (KPGO), Hawaii, with approximately 1 mm precision using phase delay observables from dedicated VLBI observations in 2016 and 2018. The two KPGO antennas are the 20 m legacy VLBI antenna and the 12 m VLBI Global Observing System (VGOS) antenna. Independent estimates of the vector between the two antennas were obtained by the National Geodetic Survey (NGS) using standard optical surveys in 2015 and 2018. The uncertainties of the latter survey were 0.3 and 0.7 mm in the horizontal and vertical components of the baseline, respectively. We applied corrections to the measured positions for the varying thermal deformation of the antennas on the different days of the VLBI and survey measurements, which can amount to 1 mm, bringing all results to a common reference temperature. The difference between the VLBI and survey results are 0.2 ± 0.4 mm, -1.3 ± 0.4 mm, and 0.8 ± 0.8 mm in the East, North, and Up topocentric components, respectively. We also estimate that the Up component of the baseline may suffer from systematic errors due to gravitational deformation and uncalibrated instrumental delay variations at the 20 m antenna that may reach ± 10 and -2 mm, respectively, resulting in an accuracy uncertainty on the order of 10 mm for the relative heights of the antennas. Furthermore, possible tilting of the 12 m antenna increases the uncertainties in the differences in the horizontal components to 1.0 mm. These results bring into focus the importance of (1) correcting to a common reference temperature the measurements of the reference points of all geodetic instruments within a site, (2) obtaining measurements of the gravitational deformation of all antennas, and (3) monitoring local motions of the geodetic instruments. These results have significant implications for the accuracy of global reference frames that require accurate local ties between geodetic instruments, such as the International Terrestrial Reference Frame (ITRF).

Maintenance infliximab does not result in increased abscess development in fistulizing Crohn's disease: results from the ACCENT II study.

BACKGROUND: Rapid fistula healing may predispose Crohn's disease patients to abscess development. AIM: Data from ACCENT II were analysed to determine whether fistula-related abscess development is affected by infliximab exposure. METHODS: Following infliximab 5 mg/kg infusions at weeks 0, 2 and 6, patients were evaluated for fistula response for two consecutive visits at least 4 weeks apart. Patients (N = 282) were randomized at week 14 to either placebo or infliximab 5 mg/kg every 8 weeks through week 46. If response was lost at or after week 22, patients could crossover to a 5 mg/kg higher infliximab dose. Fistula-related abscesses were diagnosed by physical examination or by imaging procedures according to usual practice. RESULTS: Infliximab exposure was approximately twofold higher for the infliximab maintenance group. Twenty-one (15%) patients in the infliximab maintenance group had at least one newly developed fistula-related abscess compared with 27 (19%) in the placebo maintenance group (P = 0.526). The proportion of patients with a new fistula-related abscess was similar regardless of whether or not patients crossed over to a 5 mg/kg higher infliximab dose. The number of fistula-related abscesses diagnosed over time did not differ between groups. CONCLUSION: Abscess development in patients with fistulizing Crohn's disease is not dependent on cumulative infliximab exposure.

Physical activity as a risk factor for osteoarthritis of the knee.

A case-control study was conducted to evaluate the association between knee osteoarthritis (OA) and physical activity (PA) among a community group aged 40 years and older. Case patients (85 males, 154 females) had radiologically confirmed knee OA with grade 2+ changes, according to Kellgren and Lawrence criteria. Control subjects (85 males, 154 females) had no radiologic evidence of knee OA. A statistically significant positive association between high PA level and knee OA was observed for women, with an age-adjusted odds ratio (OR) of 1.66 and 95% confidence interval (CI) of 1.01 to 2.72. In men no association was observed (OR = 0.95; 95% CI, 0.49 to 1.83). These associations persisted when controlling simultaneously for potential confounders including age, obesity, history of knee injury, and socioeconomic status, indicating that the OA-PA association is limited to women. One possible explanation is that risk factors for knee OA are influenced by hormones.

Peripheral nerve surgery of the foot and ankle. A review of current principles.

Planning for peripheral nerve surgery requires consideration of a multitude of factors, as well as a surgeon's meticulous skill and experience. With so little room for error, every advantage must be taken to optimize repair. Peripheral nerve surgery of the foot and ankle is an underappreciated area of neurosurgery with comparatively limited published reports and data. The authors reviewed the current trends in the surgical management of peripheral nerve injuries of the foot and ankle in the hope that an understanding of the basic principles involved will allow for future study of the results of such surgery by more surgeons who deal with these problems.

Career management, not transition.

Managing your career means more than just changing jobs. It's a process that you can plan and control. Find out the steps to shaping your professional future in this article.

Human resource management for solo and small group medical practices.

This article provides an approach to the recruitment and selection of staff with a review of indirect cost and complements. In screening candidates, sensitivity to discrimination issues can avoid liabilities. Compensation and benefits should be structured to both attract and retain competent personnel. Performance management coordinates short- and long-term objectives, individual goals, and business objectives. Documentation of performance and grievance and appeal procedures are important tools for any practice. Use of part-time staff is a popular cost control measure.

Joint-specific prevalence of osteoarthritis of the hand.

PURPOSE: To quantify the prevalence of radiographic hand osteoarthritis (OA) among a group of community-dwelling individuals. Joint-specific prevalence rates/100 of radiographic OA of the hand were quantified and reported by age, gender, and dominant hand. METHODS: Data from a community-based, longitudinal study designed to follow the natural history of OA were used. Participants were ambulatory men and women, ages 40 years and older, with and without radiographic hand OA (N = 3327). Bilateral hand OA was examined at three joints: second distal interphalangeal joints (DIP), third proximal interphalangeal joints (PIP), and first carpometacarpal joint of the thumb (CMC). The ordinal scale of Kellgren and Lawrence (0-4) was used to determine OA status (grades 2+). RESULTS: Radiographic hand OA status was determined for all persons in the study group comprised of 2302 women (69%) and 1025 men (31%). The sample sizes for the age groups (years) were 532 (40-49), 905 (50-59), 998 (60-69), 749 (70-79), and 143 (80+). Overall, the DIP joint demonstrated the highest OA prevalence, while the PIP joint showed the lowest prevalence. Joint-specific hand OA prevalence rates for second DIP, third PIP, and first CMC were 35%, 18%, and 21%, respectively. Expectedly, hand OA prevalence for all joints increased with age. With exceptions, women demonstrated higher hand OA prevalence rates for the three sites examined. However, among men aged 40-49, the second DIP joint OA rate was higher (13%) compared with women (8%). Additionally, men in that age group demonstrated an elevated first CMC joint OA rate (9%) compared with women (5%). Gender-specific hand dominance analyses demonstrated that the majority of individuals with unilateral second DIP or third PIP OA presented in their dominant hand. However, among those with unilateral first CMC OA, both genders displayed a tendency to present in their nondominant hand. CONCLUSION: These findings suggest the need for further investigation of the role gender can play in the development of hand OA in populations under 60 years of age. Additional epidemiological studies addressing hand OA will serve to bridge the gap between the current levels of knowledge about the knee and the hand. The disease burden of hand OA affects a large percentage of the population. Research efforts that more exhaustively characterize the prevalence of hand OA may contribute toward interventions that, ultimately, impact a rapidly growing segment of our population.

Plantar pressure measurements. Rational shoe-wear in patients with rheumatoid arthritis.

Objective measurements of forefoot plantar pressures were taken on 25 patients with rheumatoid arthritis. The Harris mat footprint test and the Brand slipper sock test were used to assess both compressive shearing forces. The Harris mat footprint test is a static used when the patient is unshod. The Brand slipper sock test is a dynamic test used while the shoe is worn. An experimental sandal was designed and used for the treatment of symptomatic forefoot callosities. The Harris mat footprint test results improved dramatically after the patients had worn an experimental sandal for six months. The Brand slipper sock test results showed marked diminution in the pressure profile while the patients wore the experimental sandal. All of the patients improved in their functional abilities while wearing the experimental sandal.

Factors associated with poor results following arthroscopic subcutaneous lateral retinacular release.

Forty-eight patients who underwent 55 arthroscopic subcutaneous lateral retinacular releases with an average follow-up period of 15 months were examined. Advancing age, postoperative hemarthrosis, incomplete release, incomplete quadriceps rehabilitation, and severe ligamentous laxity are factors that may contribute to a poor result following this procedure. In patient selection the increased risk of poor results in patients older than 30 years of age and in those with generalized ligamentous laxity must be considered. During surgery, release of the tight lateral tether is essential to produce a positive "tilt" sign, signifying complete release. Although postoperative hemarthrosis is usually associated with immediate morbidity, it can ultimately lead to poor results. Incomplete or incorrect quadriceps rehabilitation is almost always associated with a compromised result.

Smoking and osteoarthritis: is there an association? The Clearwater Osteoarthritis Study.

OBJECTIVE: To evaluate the association between cigarette smoking and the subsequent development of osteoarthritis (OA) at four separate sites: knee, hand, foot and cervical spine. METHODS: This cohort study examined 2505 men and women aged 40 years and older participating in the longitudinal Clearwater Osteoarthritis Study (1988-current). Biennial physical exams, including serial radiographs, as well as historical information, were collected. The Lawrence and Kellgren ordinal scale was used to determine radiological evidence of the study outcome, OA. Self-reported history of smoking behavior was used to determine the study exposure. Smoking was classified using four approaches: (1) ever/never, (2) former/never, (3) current/never, and (4) dose. RESULTS: Among the individuals at study entry, radiologically confirmed incident OA was detected during the follow-up period at four sites: knee (32%), hand (49%), foot (28%), and cervical spine (52%). Approximately 11% were self-reported current smokers. Unadjusted analyses indicated that individuals classified as current smokers demonstrated significant levels of protection from OA at all four sites investigated. However, adjusted point estimates ranging from 0.60-1.48 were suggestive of no association between smoking and the development of OA at any of the four sites investigated. CONCLUSION: Based upon the findings of this prospective study, smoking does not appear to convey a clinically significant level of protection against the development of radiologically-confirmed OA. While these findings corroborate previous studies indicating no association between smoking and OA, anecdotal evidence warrants investigation into the role that cigarette smoking may play in the symptomatology of OA.

Osteoarthritis pain and weather.

OBJECTIVE: To evaluate the association between weather (barometric pressure, precipitation and temperature) and pain among individuals with osteoarthritis (OA) (n=154) at the following sites: neck, hand, shoulder, knee and foot. METHODS: This prospective study evaluated men and women, aged 49-90 yr, participating in a community-based, osteoarthritis exercise study (June 1998-January 2002). Weekly self-reported pain scores were collected using a visual analogue scale. Statistical tests, including regression and correlation analyses, were conducted. P values < 0.001 were considered significant. RESULTS: The total number of pain recordings varied by site, ranging from 2269 (feet) to 6061 (hands). The mean temperature was 23 degrees C with a low of 0 degrees C and a high of 36 degrees C. Precipitation levels ranged from 0.00-21.08 cm, with a mean of 0.36 cm. Most associations explored produced non-significant findings. However, among women with hand OA, higher pain was significantly associated with days of rising barometric pressure (P < 0.001). CONCLUSION: Among a population of exercisers aged 49 yr and older, overall these findings did not support the hypothesis that weather is associated with pain. While some associations were suggestive of a relationship, largely these findings indicate that weather is quite modestly, if at all, associated with pain from OA.

Retrospective analysis of neurapraxia and axonotmesis injuries of select peripheral nerves of the foot and ankle and their conservative and surgical treatment (external neurolysis and neurectomy).

There is a paucity of scientific literature that has reviewed the conservative and surgical treatment efficacy for the management of injuries causing neurapraxia and axonotmesis. This retrospective study evaluates the clinical outcomes of certain treatments for these injuries. Twenty-seven patients fulfilled the inclusion/exclusion criteria for the study, and represented both genders and a wide variety of ages, weights, levels of education, and backgrounds. Surgical intervention resulted in a slightly better clinical outcome when compared to conservative therapies. Patients undergoing surgery for a single nerve problem improved more than those who underwent surgery when three or more nerves were involved. Failure was most often associated with: 1) multiple nerve injuries, 2) a previous history of psychopathology, and 3) application of conservative therapy without surgical intervention for single nerve injury.

History of acute knee injury and osteoarthritis of the knee: a prospective epidemiological assessment. The Clearwater Osteoarthritis Study.

OBJECTIVE: To evaluate the association between acute joint injury to the knee and knee osteoarthritis (OA). DESIGN: Prospective cohort. Sample size = 1,436. Men and women aged 40 years and older participating in the population-based Clearwater Osteoarthritis Study (1988-current) with biennial physical exams including serial radiographs. Radiologically confirmed knee OA = 27%; self-reported knee injury = 11%. Lawrence and Kellgren ordinal scale was used to determine radiological evidence of the study outcome, knee OA. Self-reported history of knee injury was used to determine the study exposure. RESULTS: Individuals with a history of knee injury were 7.4 (95% C.I. 5.9-9.4) times as likely to develop knee OA than were those individuals who did not have a history of knee injury. CONCLUSION: Acute knee joint injury appears to be a risk factor for the development of knee OA. Prevention strategies for OA should be targeted to those individuals with a history of acute knee injury.

Correlation of roentgenographic patterns and clinical manifestations of symptomatic idiopathic osteoarthritis of the knee.

A retrospective review of weight-bearing roentgenograms of 2197 knees in 1894 patients with symptomatic idiopathic osteoarthritis (IOA) revealed six different patterns of tibiofemoral deformity. Five of these patterns expand the taxonomic concepts of Ahlback; the sixth, "nonproliferative," was previously undescribed. It was seen exclusively in patients with varus disease and was characterized by a lack of reactive bony changes. Knees with degenerative changes in the medial compartment constituted the majority of cases (63%). The average age of patients was 72 years for those with varus disease, 79 years for those with valgus disease, and 84 years for those with patellofemoral arthritis (PFA). Bilateral involvement was common only in patients with PFA (79%), suggesting a developmental cause for this subset. There was a female predominance in valgus and patellofemoral disease. The authors report here on a classification system of IOA that has been designed and modified to reflect the unique roentgenographic, epidemiologic, and clinical characterization of the six subsets.