Screw-Home Movement of the Tibiofemoral Joint during Normal Gait: Three-Dimensional Analysis

Background

The purpose of this study was to evaluate the screw-home movement at the tibiofemoral joint during normal gait by utilizing the 3-dimensional motion capture technique.

Methods

Fifteen young males and fifteen young females (total 60 knee joints) who had no history of musculoskeletal disease or a particular gait problem were included in this study. Two more markers were attached to the subject in addition to the Helen-Hayes marker set. Thus, two virtual planes, femoral coronal plane (P_f) and tibial coronal plane (P_t), were created by Skeletal Builder software. This study measured the 3-dimensional knee joint movement in the sagittal, coronal, and transverse planes of these two virtual planes (P_f and P_t) during normal gait.

Results

With respect to kinematics and kinetics, both males and females showed normal adult gait patterns, and the mean difference in the temporal gait parameters was not statistically significant (p > 0.05). In the transverse plane, the screw-home movement occurred as expected during the pre-swing phase and the late-swing phase at an angle of about 17°. However, the tibia rotated externally with respect to the femur, rather than internally, while the knee joint started to flex during the loading response (paradoxical screw-home movement), and the angle was 6°.

Conclusions

Paradoxical screw-home movement may be an important mechanism that provides stability to the knee joint during the remaining stance phase. Obtaining the kinematic values of the knee joint during gait can be useful in diagnosing and treating the pathological knee joints.     

A Robust Approach for Blind Detection of Balanced Chromosomal Rearrangements with Whole‐Genome Low‐Coverage Sequencing

Balanced chromosomal rearrangement (or balanced chromosome abnormality, BCA) is a common chromosomal structural variation. Next‐generation sequencing has been reported to detect BCA‐associated breakpoints with the aid of karyotyping. However, the complications associated with this approach and the requirement for cytogenetics information has limited its application. Here, we provide a whole‐genome low‐coverage sequencing approach to detect BCA events independent of knowing the affected regions and with low false positives. First, six samples containing BCAs were used to establish a detection protocol and assess the efficacy of different library construction approaches. By clustering anomalous read pairs and filtering out the false‐positive results with a control cohort and the concomitant mapping information, we could directly detect BCA events for each sample. Through optimizing the read depth, BCAs in all samples could be blindly detected with only 120 million read pairs per sample for data from a small‐insert library and 30 million per sample for data from nonsize‐selected mate‐pair library. This approach was further validated using another 13 samples that contained BCAs. Our approach advances the application of high‐throughput whole‐genome low‐coverage analysis for robust BCA detection—especially for clinical samples—without the need for karyotyping.     

Investigation of the binding and cleavage characteristics of N1 neuraminidases from avian,seasonal, and pandemic influenza viruses using saturation transfer difference nuclear magnetic resonance

Objectives

The main function of influenza neuraminidase (NA) involves enzymatic cleavage of sialic acid from the surface of host cells resulting in the release of the newly produced virions from infected cells, as well as aiding the movement of virions through sialylated mucus present in the respiratory tract. However, there has previously been little information on the binding affinity of different forms of sialylated glycan with NA. Our objectives were then to investigate both sialic acid binding and cleavage of neuraminidase at an atomic resolution level.

Design

Nuclear magnetic resonance (NMR) spectroscopy was used to investigate pH and temperature effects on binding and cleavage as well as to interrogate the selectivity of human-like or avian-like receptors for influenza neuraminidase N1 derived from a range of different influenza virus strains including human seasonal H1N1, H1N1pdm09 and avian H5N1.

Results

We demonstrated that an acidic pH and physiological temperature are required for efficient NA enzymatic activity; however a change in the pH had a minimum effect on the NA-sialic acid binding affinity. Our data comparing α-2,3- and α-2,6-sialyllactose indicated that the variation in neuraminidase activity on different ligands correlated with a change in binding affinity. Epitope mapping of the sialylglycans interacting with NAs from different viral origin showed different binding profiles suggesting that different binding conformations were adopted.

Conclusions

The data presented in this study demonstrated that physicochemical conditions (pH in particular) could affect the NA enzymatic activity with minor effect on ligand binding. NA cleavage specificity seemed to be associated with a difference in binding affinity to different ligands, suggesting a relationship between the two events. These findings have implications regarding the replication cycle of influenza infection in the host where different sialidase activities would influence penetration through the respiratory mucin barrier and the release of the newly generated virus from the infected cells.     

Surgical suture assembled with polymeric drug-delivery sheet for sustained,local pain relief

Surgical suture is a strand of biocompatible material designed for wound closure, and therefore can be a medical device potentially suitable for local drug delivery to treat pain at the surgical site. However, the preparation methods previously introduced for drug-delivery sutures adversely influenced the mechanical strength of the suture itself – strength that is essential for successful wound closure. Thus, it is not easy to control drug delivery with sutures, and the drug-delivery surgical sutures available for clinical use are now limited to anti-infection roles. Here, we demonstrate a surgical suture enabled to provide controlled delivery of a pain-relief drug and, more importantly, we demonstrate how it can be fabricated to maintain the mechanical strength of the suture itself. For this purpose, we separately prepare a drug-delivery sheet composed of a biocompatible polymer and a pain-relief drug, which is then physically assembled with a type of surgical suture that is already in clinical use. In this way, the drug release profiles can be tailored for the period of therapeutic need by modifying only the drug-loaded polymer sheet without adversely influencing the mechanical strength of the suture. The drug-delivery sutures in this work can effectively relieve the pain at the surgical site in a sustained manner during the period of wound healing, while showing biocompatibility and mechanical properties comparable to those of the original surgical suture in clinical use.     

A geopolymer route to micro- and meso-porous carbon

Hexagonal and wormhole-type mesoporous geopolymers were developed by controlling the concentration of a structure directing agent (cetrimonium bromide, CTAB) with fixed ratios of Si/Al, KOH/(Si + Al), and H₂O/(Si + Al), and their detailed porous structures were confirmed by TEM, N₂ adsorption–desorption and X-ray diffraction measurements. The as-prepared geopolymers were then used as templates to replicate porous carbons with various structures and porosities for CO₂ adsorption. To understand the correlation between the CO₂ adsorptivity and porous structures, we tuned the porosity of the geopolymer-templated carbons by modifying the structures of the geopolymers. The porous carbons obtained from the hexagonal-type porous geopolymers were found to be composed of the aggregates of carbon nanowires exhibiting large particles, while those obtained from the wormhole-like porous geopolymers were determined to be wormhole type as well, as evidenced by TEM and X-ray diffraction studies. According to the CO₂ adsorption isotherms of the porous carbons, the aggregates of carbon nanowires exhibited the highest CO₂ adsorptivity due to their highest microporosity and largest specific surface area.

We report the synthesis of microporous carbon through a geopolymer route starting from natural clay kaolinite.     

Exeter Short Stems Compared With Standard Length Exeter Stems : Experience From the Australian Orthopaedic Association National Joint Replacement Registry

The standard Exeter stem has a length of 150 mm with offsets 37.5 to 56 mm. Shorter stems of lengths 95, 115 and 125 mm with offsets 35.5 mm or less are available for patients with smaller femurs. Concern has been raised regarding the behavior of the smaller implants. This paper analyzed data from the Australian Orthopaedic Association National Joint Replacement Registry comparing survivorship of stems of offset 35.5 mm or less with the standard stems of 37.5 mm offset or greater. At 7 years, there was no significant difference in the cumulative percent revision rate in the short stems (3.4%, 95% CI 2.4-4.8%) compared with the standard length stems (3.5%, 95% CI 3.3-3.8%) despite its use in a greater proportion of potentially more difficult developmental dysplasia of the hip cases.     

LCP distal ulna hook plate as alternative fixation for fifth metatarsal base fracture

Intramedullary screw fixation is the most common treatment for fifth metatarsal base fractures. Screw application does not achieve accurate reduction in fracture with small fragments, osteoporotic bone, or Lawrence zone 1 fractures, however. On the basis of similar anatomical architectures between the distal ulna and the fifth metatarsal base, the purpose of this study was to assess the results of a locking compression plate (LCP) distal ulna hook plate in stabilizing displaced zone 1 or 2 fifth metatarsal base fractures. Nineteen patients with Lawrence zone 1 (n = 12) or 2 (n = 7) fractures of the fifth metatarsal base were treated surgically with an LCP distal ulna hook plate. The patients were evaluated clinically and radiographically, and functional outcomes were graded by using the American Orthopaedic Foot and Ankle Society (AOFAS) midfoot scoring system. Radiographic bony union was obtained in all patients, at an average of 7.4 weeks. The mean AOFAS midfoot score improved from 26 (range, 0–45) preoperatively to 94 (range, 72–100) points at the final follow-up. There were three patients with post-traumatic cubometatarsal arthrosis and one patient with sural nerve neuropraxia. In our experience, the distal ulna hook plate achieves a high rate of bony consolidation and anatomically suitable fixation in zone 1 or 2 fifth metatarsal base fractures. We also suggest that the LCP distal ulna hook plate should be considered as an alternative treatment in multifragmentary, osteoporotic, and tuberosity avulsion (zone 1) fifth metatarsal base fractures.