Water quality parameters and current velocities were measured in depth profiles at a series of sampling stations throughout the upper estuary of the Derwent River, Tasmania, during 1988-89. The estuary was severely degraded, with low dissolved oxygen and high sulfide concentrations in benthic saline waters for seven months of the year. A simple two-layer one-dimensional box model was constructed to examine the relationships between water quality, estuarine mixing and river flows. Flow events critical to the dynamics of water quality in the upper estuary are described. An initial analysis of the impact of changes to the flow regime of the Derwent River on the Derwent estuary indicates that hydroelectric storage operations have led to a decrease in the frequency of flows required to flush the estuary, superimposed on climate-induced changes. Recommendations are made for possible flushing flows necessary to improve estuarine water quality.
nset of Hallux Limitus (HL) commonly affects patients after contusion injuries and after one of the two most common surgical procedures for foot pathologies, a bunionectomy or a cheilectomy. [1][2][3] HL is a pathology of degenerative arthritis in the first metatarsophalangeal joint (MTJ) of the first toe, or a consequence of a runner's injury this pathology affects both adolescents and adults.
2-8The literature consensus has long assumed that pain reduction is a predictable result of properly selected surgical patients, but that improvement in the arc of functional motion about the great toe should not be expected. Before HL repair with cheilectomy, radiographs typically reveal osteophyte formation in addition to dorsal exostosis, narrowing of the joint space, subchondral sclerosis, and flattening of the metatarsal head. Osteophyte formation is common on the first metatarsal head (both plantar and dorsal sides) causing inflammation, edema, pain, and reduced range of motion (ROM). Action of the hallux requires plantarflexion of the first metatarsal bone, which allows the proximal phalanx to dorsiflexion. This bidirectional hinge action must occur with each step. 8,9 The normal smooth motion of the proximal phalanx over the head of the metatarsal is disrupted leading to painful compression of the phalanx against the head of the metatarsal as the joint is dorsiflexed.Standard of care for HL includes orthoses, NSAIDs and home stretching exercises, but these protocols have had limited success in regaining range of motion because the stretching was not biomechanically correct and did not have measurable, dynamic tension.
The authors present a brief history of the development of the Ilizarov external fixator, and the classic uses associated with it. A preliminary study of 3 patients using 56 frames is presented. The Ilizarov external fixator is successfully used in these cases in place of traditional fixation.
Dynamic splinting was effective in reducing contracture of postoperative hallux limitus in this study; experimental patients gained a mean 250% improvement in AROM. This modality should be considered for standard of care in treating postoperative hallux limitus.
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