Total knee arthroplasty using anatomic alignment can produce mid-flexion laxity

Background

Modern total knee arthroplasty offers two different alignment techniques, anatomic or mechanical, based on the bone axes selected for implantation of the prosthetic components. This study examined the axes of both during simulated physiologic knee joint motion, as well as the relationship between these axes and the implication of medial–lateral soft tissue balance in total knee arthroplasty.

Methods

Seven fresh-frozen, lower limb specimens were stripped at a level 15 cm from joint line, leaving the joint capsule, quadriceps muscle, hamstring tendons and ligamentous structures intact. Specimens were anatomically marked to track precise movements of the tibia and femur — from which both alignment axes were determined. Medial and lateral joint spacings were tracked to determine collateral ligament laxity. A kneeling simulator jig produced physiologic knee motion.

Findings

Measurements of medial and lateral joint spacings revealed statistically significant differences at all flexion angles between the two alignment axes. The anatomic alignment axes' pattern demonstrates mid-flexion lateral opening and late-flexion medial joint space opening — mechanical axes revealing a consistent 2–3 mm larger lateral than medial joint space.

Interpretation

In an effort to produce a more natural feeling knee replacement, understanding the normal kinematic soft tissue balance can serve as a useful reference point, and mid flexion laxity is an important clinical concern. With currently available total knee arthroplasty designs, mechanical alignment is preferable to anatomic alignment because it creates consistent spacing, which can be addressed by ligament lengthening or adjustments in femoral component positioning.     

Proposal for an approach with default values for the protection offered by PPE, under European new or existing substance regulations

Introduction of personal protective equipment (PPE) in the process of quantitative exposure and risk assessment should be addressed carefully. PPE which have been designed and manufactured according to CE-criteria and have proved to pass relevant test criteria, can be classified as "proper functioning". However, test criteria for PPE are not equal to levels of protection which can be achieved in the workplace, because actual workplace exposure scenarios, fit, maintenance and storage may differ substantially from the test conditions.The proper use of PPE is related to issues which form a part of a PPE-programme. Such a programme should be implemented in a company to ensure selection of proper PPE and information, training and instruction of employees how to wear PPE properly.Assigned protection factors (APFs) for different designs of respiratory protective devices (RPD) have been introduced to quantify effectiveness of RPD in the workplace. Similar APFs are proposed for dermal protection (gloves and clothing). In general biological monitoring studies show lower reduction of internal exposure than estimated by reduction of external exposure. Therefore, conservative estimates of protection by PPE, i.e. the lowest APFs, are proposed for risk assessment purposes if "proper use of proper functioning" PPE as part of a PPE-programme cannot be demonstrated.     

Determinants of Effective Cooling During Endovascular Hypothermia

Background

Therapeutic hypothermia is a promising neuroprotective therapy with multiple mechanisms of action. We demonstrated the feasibility of thrombolysis combined with endovascular hypothermia, but not all patients achieved effective cooling. We sought to identify the factors that determined effective cooling.

Methods

In 26 patients who underwent endovascular hypothermia, we computed four measures of effective cooling: time to reach target; Area-Under-the-Curve (AUC) 34 ratio; AUC-34; and AUC-35. By multivariate regression, we examined the effects of age, weight, starting temperature, body mass index, body surface area (BSA), gender, shivering, and total meperidine dose on the four outcome measures.

Results

In univariate analyses, all four outcome measures were significantly influenced by BSA (p?p?r?=?0.6, p?p?p?p?p?p?Conclusions The most important determinant of effective cooling during endovascular hypothermia is BSA; larger patients are more difficult to cool and maintain in therapeutic range. Older patients cool more quickly. Shivering was well controlled by the combination of meperidine, buspirone, and surface counter-warming and only minimally influenced cooling effectiveness. Future trials of therapeutic hypothermia may include added measures to cool larger patients more effectively.     

Concentration levels of IL-10 and TNFα cytokines in patients with human papilloma virus (HPV) DNA⁺ and DNA⁻ cervical lesions

The present study was performed to assess the immune response in women with human papilloma virus (HPV) DNA? and DNA? cervical lesions. Eighty women with cervical lesions (age range?=?25-70 years) and 20 healthy individuals (control group) were enrolled in the study. Lesions were cytologically classified into four groups: ASC-US (20), CINI (30), CINII-III (16), and cervical carcinoma (14) prior to HPV DNA detection. Estimation of interleukin (IL)-10 and tumor necrosis factor (TNF)-α levels in cervical secretions and serum of the studied patients was performed utilizing ELISA. PCR screening kits were used to detect HPV DNA in cervical smears obtained from the studied cases with the different lesions. IL-10 levels in cervical secretions of HPV DNA? were significantly greater than those from DNA? patients (i.e., 88.73 vs 24.00 pg/ml) and from controls (i.e., 88.73 vs 8.27 pg/ml) and the levels were higher in DNA? patients than in controls (i.e., 24.00 vs 8.27 pg/ml). In comparison, serum IL-10 levels in these patients did not significantly differ from control values (i.e., 13.69 vs 12.16 vs 9.99 pg/ml, respectively). TNFα levels in cervical secretions of the HPV DNA? and DNA? cases did not significantly differ from values for the controls (i.e., 12.18 vs 9.90 vs 7.90 pg/ml, respectively). Serum TNFα of these patients also did not differ significantly from controls (i.e., 11.59 vs 11.90 vs 10.83 pg/ml, respectively). The detected levels of IL-10 in cervical secretions of patients with HPV DNA? lesions was significantly higher than in their sera, while secretion TNFα levels were nominally greater than sera values. Lastly, higher levels of IL-10 were observed in secretions of 10-14 (71.4%) patients who had progressive cervical lesions (HSIL and cervical cancer stages) who were HPV DNA? than observed in 20 of 66 (30.0%) of DNA? patients with similar progressive lesions. In general, the higher levels of IL-10 than of TNFα suggested a potential down-modulation of tumor-specific immune responses to HPV-infected lesions. This phenomenon appears to provide a tumor 'progressive' microenvironment in these particular patients.     

Temporal precision and reliability in the velocity regime of a hair-cell sensory system: the mechanosensory lateral line of goldfish, Carassius auratus

Fish and aquatic frogs detect minute water motion by means of a specialized mechanosensory system, the lateral line. Ubiquitous in fish, the lateral-line system is characterized by hair-cell based sensory structures across the fish's surface called neuromasts. These neuromasts occur free-standing on the skin as superficial neuromasts (SN) or are recessed into canals as canal neuromasts. SNs respond to rapid changes of water velocity in a small layer of fluid around the fish, including the so-called boundary layer. Although omnipresent, the boundary layer's impact on the SN response is still a matter of debate. For the first time using an information-theoretic approach to this sensory system, we have investigated the SN afferents encoding capabilities. Combining covariance analysis, phase analysis, and modeling of recorded neuronal responses of primary lateral line afferents, we show that encoding by the SNs is adequately described as a linear, velocity-responsive mechanism. Afferent responses display a bimodal distribution of opposite Wiener kernels that likely reflected the two hair-cell populations within a given neuromast. Using frozen noise stimuli, we further demonstrate that SN afferents respond in an extremely precise manner and with high reproducibility across a broad frequency band (10-150 Hz), revealing that an optimal decoder would need to rely extensively on a temporal code. This was further substantiated by means of signal reconstruction of spike trains that were time shifted with respect to their original. On average, a time shift of 3.5 ms was enough to diminish the encoding capabilities of primary afferents by 70%. Our results further demonstrate that the SNs' encoding capability is linearly related to the stimulus outside the boundary layer, and that the boundary layer can, therefore, be neglected while interpreting lateral line response of SN afferents to hydrodynamic stimuli.     

OGG1 gene sequence variation in head and neck cancer patients in Pakistan

In Pakistani culture tobacco use is very high and a well known risk factor for developing head and neck cancer (HNC), tobacco smoke containing high quantities of chemical carcinogens such as aromatic amines and reactive oxygen species. OGG1 is the primary enzyme in the base excision repair (BER) pathway, responsible for the excision of 7, 8-dihydro-8-oxoguanine, a mutagenic base byproduct that occurs as a result of exposure to reactive oxygen species. Groups of 300 already diagnosed HNC patients along with normal controls were included in this study. PCR-single-strand conformation polymorphism and DNA sequencing were used to analyze the whole coding region of OGG1 gene. Sequence analysis revealed eight novel mutations (six missense and two frame shift mutations). Frequencies of missense mutations, Asp267Asn, Ser279Gly and Ile253Phe were 0.12, 0.13 and 0.06 respectively. Frequencies of other missense mutations, 1578A> T, 1582C> T and Ala399Glu (1542C> A) were 0.13, 0.13 and 0.16, whereas values for the frame shift mutations 1582insG and 1543-1544delCT were 0.13 and 0.16. In our study, incidence of these mutations was found higher in oral cancers (p<0.002) and in smokers (p<0.002) when compared with other sites of HNC and nonsmokers, respectively. Our finding suggests that these germline mutations in OGG1 gene contribute to risk of developing HNC.     

Emergence of coryneforms in osteomyelitis and orthopaedic surgical site infections

Background

Coryneform species other than Corynebacterium diphtheriae are coming up as important pathogens with the potential to cause serious and life-threatening infections not only in immunocompromised but in immunocompetent individuals as well. The exact infectious potential of these bacteria and their rational antimicrobial treatment is a challenging but essential task.

Method

The study was conducted in the Department of Microbiology and the Department of Orthopaedics, JNMCH, AMU, Aligarh between August 2007 and May 2009. Pus samples were collected from patients of osteomyelitis and other bone infections including orthopaedic surgical site infections. The Corynebacterium species isolated in the study was identified using standard microbiological techniques and antimicrobial sensitivity testing was done by Kirby bauer disc diffusion method.

Results

A total of 312 Corynebacterium species were isolated. The majority of the coryneforms were isolated from the immunocompetent patients 270 (86.54%). C. jeikium was the most common coryneform isolated. Nearly half of the patients 153 (49.04%) had acute infection caused by Corynebacterium species after orthopaedic surgery, a quarter 66 (21.15%) had chronic infection and 72 (23.08%) patients had device-related infection. Coryneforms exhibited maximum resistance to aminoglycosides (58.65%) and P-lactams (penicillin group- 57.55%. C.jeikium was found to be the most resistant amongst all the Corynebacterium species.

Conclusion

The study highlights the fact that the coryneforms are no longer just opportunistic pathogens but they are also becoming important pathogens among immunocompetent individuals as well. The emergence of drug resistance amongst these isolates is of most concern. More studies should be done on identification and on antimicrobial susceptibility of these organisms for the proper treatment of patients with such infections.