Influenza Virus Respiratory Infection and Transmission Following Ocular Inoculation in Ferrets

While influenza viruses are a common respiratory pathogen, sporadic reports of conjunctivitis following human infection demonstrates the ability of this virus to cause disease outside of the respiratory tract. The ocular surface represents both a potential site of virus replication and a portal of entry for establishment of a respiratory infection. However, the properties which govern ocular tropism of influenza viruses, the mechanisms of virus spread from ocular to respiratory tissue, and the potential differences in respiratory disease initiated from different exposure routes are poorly understood. Here, we established a ferret model of ocular inoculation to explore the development of virus pathogenicity and transmissibility following influenza virus exposure by the ocular route. We found that multiple subtypes of human and avian influenza viruses mounted a productive virus infection in the upper respiratory tract of ferrets following ocular inoculation, and were additionally detected in ocular tissue during the acute phase of infection. H5N1 viruses maintained their ability for systemic spread and lethal infection following inoculation by the ocular route. Replication-independent deposition of virus inoculum from ocular to respiratory tissue was limited to the nares and upper trachea, unlike traditional intranasal inoculation which results in virus deposition in both upper and lower respiratory tract tissues. Despite high titers of replicating transmissible seasonal viruses in the upper respiratory tract of ferrets inoculated by the ocular route, virus transmissibility to naïve contacts by respiratory droplets was reduced following ocular inoculation. These data improve our understanding of the mechanisms of virus spread following ocular exposure and highlight differences in the establishment of respiratory disease and virus transmissibility following use of different inoculation volumes and routes

Biomechanical risk factors in the development of medial tibial stress syndrome in distance runners

Background: We investigated the relationship between functional and static foot posture and medial tibial stress syndrome in distance runners. Methods: Twenty-eight runners with a clinical diagnosis of medial tibial stress syndrome and 12 asymptomatic runners were assessed with the Foot Posture Index to measure static overpronation. Range of motion was measured at the talocrural joint, with the knee extended and flexed as was range of motion at the first metatarsophalangeal joint and the angular difference between the neutral and relaxed calcaneal stance positions. Each participant was then videotaped while running on a treadmill shod and unshod. This videotape was analyzed using freeze frame to identify abnormal or mistimed pronation at each phase of gait. The results were analyzed using logistic regression to give the probability that a runner is likely to experience medial tibial stress syndrome, predicted from the static measurements and dynamic observations. Results: Variables identified as being significant predictors of medial tibial stress syndrome were the difference between the neutral and relaxed calcaneal stance positions, range of motion of the talocrural joint with the knee extended, early heel lift and abductory twist during gait, and apropulsive gait. Conclusion: Runners with suspected symptoms of medial tibial stress syndrome should be assessed dynamically and statically for abnormal or mistimed pronation

The function of the midtarsal joint: a review of the literature

The midtarsal joint (MTJt) consists of the combined articulations of the talonvicular and calcaneocuboid joints and represent the functional articulation between the rearfoot (talus and calcaneus) and the midfoot (navicular and cuboid). The movement of the transverse tarsal region has been described as a segment rotating around two distinct axes of the MTJt; the longitudinal and the oblique. Recent research has suggested that the two axes model of the MTJt is a theory of convenience to explain clinical observation, and that the MTJt moves in a more complex manner. It has been hypothesised that the MTJt has one triplanar axis of motion, so there remains the need to investigate the practical application of this understanding in terms of how this motion affects the MTJt in gait and the implications this may have on podiatric treatment

Biomechanical consequences of total plantar fasciotomy - a review of the literature

Background: Plantar fascia release for chronic plantar fasciitis has provided excellent pain relief and rapid return to activities with few reported complications. Cadaveric studies have led to the identification of some potential postoperative problems, most commonly weakness of the medial longitudinal arch and pain in the lateral midfoot. Methods: An electronic search was conducted of the MEDLINE, ScienceDirect, Sport-Discus, EMBASE, CINAHL, Cochrane, and AMED databases. The keywords used to search these databases were plantar fasciotomy and medial longitudinal arch. Articles published between 1976 and 2008 were identified. Results: Collectively, results of cadaveric studies suggested that plantar fasciotomy leads to loss of integrity of the medial longitudinal arch and that total plantar fasciotomy is more detrimental to foot structure than is partial fasciotomy. In vivo studies, although limited in number, concluded that although clinical outcomes were satisfactory, medial longitudinal arch height decreased and the center of pressure of the weightbearing foot was excessively medially deviated postoperatively. Conclusions: Plantar fasciotomy, in particular total plantar fasciotomy, may lead to loss of stability of the medial longitudinal arch and abnormalities in gait, in particular an excessively pronated foot. Further in vivo studies on the long-term biomechanical effects of plantar fasciotomy are required. (J Am Podiatr Med Assoc 99(5): 422-430, 2009